January, 1995 PUBL 534 Heat Recovery Steam Generators First Eition
AMERICAN PETROLEUM INSTITUTE SELECTED DOCUMENTS PUBL 534 : Heat Recovery Steam Geerator! "#r!t E$#t#o "#r!t E$#t#o Front !atter Heat Recovery Steam Generators SE"#$%& 1 ' GE&ER(L SE"#$%& ) ' F$RE#UBE HE(# RE"%*ER+ S#E(! GE&ER(#%RS SE"#$%& 3 ' *ER#$"(L SHELL#UBE -(#ER#UBE HRSGs SE"#$%& 4 ' -(#ER#UBE "%$LS $&S$.E PRESSURE *ESSELS SE"#$%& 5 ' -(#ER#UBE L%- PRESSURE "(S$&G HRSG SE"#$%& / ' HE(# P$PE HRSGs (PPE&.$0 ( ' S#E(! .RU!S (PPE&.$0 B ' HE(# FLU0 (&. "$R"UL(#$%& R(#$% (PPE&.$0 " ' S%%#BL%-ERS Heat Recovery Steam Geerator!
(P$ PUBL$"(#$%& 534 F$RS# E.$#$%&, J(&U(R+ 1995 Amer#ca Petro%e&m I!t#t&te 1)) L Street, &ort2est -as2inton, ." )5
Heat Recovery Steam Geerator! Ma&'act&r#() D#!tr#*&t#o a$ Mar+et#( De,artmet
(P$ PUBL$"(#$%& 534 F$RS# E.$#$%&, J(&U(R+ 1995 Amer#ca Petro%e&m I!t#t&te
SPE"$(L &%#ES
1 (P$ PUBL$"(#$%&S &E"ESS(R$L+ (..RESS PR%BLE!S %F ( GE&ER(L &(#URE &(#URE -$#H RESPE"# #% #% P(R P(R#$"UL(R #$"UL(R "$R"U!S#(&"ES, "$R"U!S#(&"ES, L%"(L, S#( S#(#E, (&. FE.ER(L L(-S (&. REGUL(#$%&S SH%UL. BE RE*$E-E. ) (P$ $S &%# U&.ER#(6$&G U&.ER#(6$&G #% !EE# #HE .U#$ES %F E!PL%+ERS, !(&UF("#URERS, %R SUPPL$ERS #% -(R& (&. PR%PERL+ #R($& (&. E7U$P #HE$R E!PL%+EES, (&. %#HERS E0P%SE., "%&"ER&$&G HE(L#H HE(L#H (&. S(FE#+ R$S6S (&. PRE"(U#$%&S, &%R U&.ER# U&.ER#(6$&G #HE$R %BL$G(#$%&S U&.ER L%"(L, S#(#E, %R FE.ER(L L(-S 3 $&F%R!(#$%& "%&"ER&$&G S(FE#+ (&. HE(L#H R$S6S (&. PR%PER PRE"(U#$%&S -$#H RESPE"# #% P(R#$"UL(R !(#ER$(LS (&. "%&.$#$%&S SH%UL. BE %B#($&E. %B#($&E. FR%! #HE E!PL%+ER, #HE !(&UF("#URER %R SUPPL$ER %F #H(# !(#ER$(L, %R #HE !(#ER$(L S(FE#+ .(#( SHEE# 4 &%#H$&G "%&#($&E. $& (&+ (P$ PUBL$"(#$%& $S #% BE "%&S#RUE. (S GR(&#$&G (&+ R$GH#, B+ $!PL$"(#$%& %R %#HER-$SE, F%R #HE !(&UF("#URE, S(LE, %R USE %F (&+ !E#H%., (PP(R(#US, %R PR%.U"# "%*ERE. B+ LE##ERS P(#E&# &E$#HER SH%UL. (&+#H$&G "%&#($&E. $& #HE PUBL$"(#$%& PUBL$"(#$%& BE "%&S#RUE. (S $&SUR$&G (&+%&E (G($&S# L$(B$L$#+ F%R $&FR$&GE!E&# %F LE##ERS P(#E&# 5 GE&ER(LL+, (P$ S#(&.(R.S (RE RE*$E-E. (&. RE*$SE., RE(FF$R!E., %R -$#H.R(-& (# LE(S# E*ER+ F$*E +E(RS S%!E#$!ES ( %&E'#$!E E0#E&S$%& %F UP #% #-% +E(RS -$LL BE (..E. #% #H$S RE*$E- "+"LE #H$S PUBL$"(#$%& PUBL$"(#$%& -$LL &% L%&GER BE $& EFFE"# F$*E +E(RS (F#ER $#S PUBL$"(#$%& .(#E (S (& %PER(#$*E (P$ S#(&.(R. %R, -HERE (& E0#E&S$%& H(S BEE& GR(&#E., UP%& REPUBL$"(#$%& REPUBL$"(#$%& S#(#US %F #HE PUBL$"(#$%& "(& BE (S"ER#($&E. FR%! #HE (P$ (U#H%R$&G .EP(R#!E&# 8#ELEPH%&E )): /;)';< ( "(#(L%G %F (P$ PUBL$"( PUBL$" (#$%&S (&. !(#ER$(LS !(#ER$(LS $S PUBL$SHE. PUB L$SHE. (&&U(LL (&&U( LL+ + (&. UP.(#E. UP.(#E. 7U(R#ERL+ B+ (P$, 1)) L S#REE#, & -, -(SH$&G#%&, ." )5 "o=yri2t > 1995 (merican Petro?eum $nstitute
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1 (P$ PUBL$"(#$%&S &E"ESS(R$L+ (..RESS PR%BLE!S %F ( GE&ER(L &(#URE &(#URE -$#H RESPE"# #% #% P(R P(R#$"UL(R #$"UL(R "$R"U!S#(&"ES, "$R"U!S#(&"ES, L%"(L, S#( S#(#E, (&. FE.ER(L L(-S (&. REGUL(#$%&S SH%UL. BE RE*$E-E. ) (P$ $S &%# U&.ER#(6$&G U&.ER#(6$&G #% !EE# #HE .U#$ES %F E!PL%+ERS, !(&UF("#URERS, %R SUPPL$ERS #% -(R& (&. PR%PERL+ #R($& (&. E7U$P #HE$R E!PL%+EES, (&. %#HERS E0P%SE., "%&"ER&$&G HE(L#H HE(L#H (&. S(FE#+ R$S6S (&. PRE"(U#$%&S, &%R U&.ER# U&.ER#(6$&G #HE$R %BL$G(#$%&S U&.ER L%"(L, S#(#E, %R FE.ER(L L(-S 3 $&F%R!(#$%& "%&"ER&$&G S(FE#+ (&. HE(L#H R$S6S (&. PR%PER PRE"(U#$%&S -$#H RESPE"# #% P(R#$"UL(R !(#ER$(LS (&. "%&.$#$%&S SH%UL. BE %B#($&E. %B#($&E. FR%! #HE E!PL%+ER, #HE !(&UF("#URER %R SUPPL$ER %F #H(# !(#ER$(L, %R #HE !(#ER$(L S(FE#+ .(#( SHEE# 4 &%#H$&G "%&#($&E. $& (&+ (P$ PUBL$"(#$%& $S #% BE "%&S#RUE. (S GR(&#$&G (&+ R$GH#, B+ $!PL$"(#$%& %R %#HER-$SE, F%R #HE !(&UF("#URE, S(LE, %R USE %F (&+ !E#H%., (PP(R(#US, %R PR%.U"# "%*ERE. B+ LE##ERS P(#E&# &E$#HER SH%UL. (&+#H$&G "%&#($&E. $& #HE PUBL$"(#$%& PUBL$"(#$%& BE "%&S#RUE. (S $&SUR$&G (&+%&E (G($&S# L$(B$L$#+ F%R $&FR$&GE!E&# %F LE##ERS P(#E&# 5 GE&ER(LL+, (P$ S#(&.(R.S (RE RE*$E-E. (&. RE*$SE., RE(FF$R!E., %R -$#H.R(-& (# LE(S# E*ER+ F$*E +E(RS S%!E#$!ES ( %&E'#$!E E0#E&S$%& %F UP #% #-% +E(RS -$LL BE (..E. #% #H$S RE*$E- "+"LE #H$S PUBL$"(#$%& PUBL$"(#$%& -$LL &% L%&GER BE $& EFFE"# F$*E +E(RS (F#ER $#S PUBL$"(#$%& .(#E (S (& %PER(#$*E (P$ S#(&.(R. %R, -HERE (& E0#E&S$%& H(S BEE& GR(&#E., UP%& REPUBL$"(#$%& REPUBL$"(#$%& S#(#US %F #HE PUBL$"(#$%& "(& BE (S"ER#($&E. FR%! #HE (P$ (U#H%R$&G .EP(R#!E&# 8#ELEPH%&E )): /;)';< ( "(#(L%G %F (P$ PUBL$"( PUBL$" (#$%&S (&. !(#ER$(LS !(#ER$(LS $S PUBL$SHE. PUB L$SHE. (&&U(LL (&&U( LL+ + (&. UP.(#E. UP.(#E. 7U(R#ERL+ B+ (P$, 1)) L S#REE#, & -, -(SH$&G#%&, ." )5 "o=yri2t > 1995 (merican Petro?eum $nstitute
F%RE-%R. (P$ =u@?ications may @e use @y anyone esirin to o so Every eAAort 2as @een mae @y t2e $nstitute to assure t2e accuracy an re?ia@i?ity oA t2e ata containe in t2em 2oever, t2e $nstitute maCes no re=resentation, arranty, arranty, or uarantee in connection it2 t2is =u@?ication an 2ere@y eD=ress?y isc?aims any ?ia@i?ity or res=onsi@i?ity Aor ?oss or amae resu?tin Arom its use or Aor t2e vio?ation oA any Aeera?, state, or munici=a? reu?ation it2 2ic2 t2is =u@?ication may conA?ict Sueste revisions are invite an s2ou? @e @ e su@mitte to t2e irector oA t2e !anuAacturin, .istri@ution an !arCetin .e=artment, (merican Petro?eum $nstitute,
1)) L Street, & -, -, -as2inton, -as2inton, ." )5
Heat Recovery Steam Generators
SE"#$%& 1 ' GE&ER(L 11 Sco=e #2is =u@?ication =rovies uie?ines Aor t2e se?ection or eva?uation oA 2eat recovery steam enerator HRSG: systems .etai?s oA re?ate eui=ment esins are consiere on?y 2ere t2ey interact it2 t2e HRSG system esin #2is =u@?ication oes not =rovie ru?es Aor esin, @ut inicates areas t2at nee attention an oAAers inAormation inAormation an escri=tion oA HRSG ty=es avai?a@?e to t2e esiner or user to ai in t2e se?ection oA t2e a==ro=riate HRSG system #2e HRSG systems iscusse are t2ose current?y in inustry use ( enera? escri=tion oA eac2 HRSG system @eins Sections ) t2rou2 5 Se?ection oA an HRSG system Aor escri=tion oes not im=?y t2at ot2er systems are not avai?a@?e nor recommene !any iniviua? Aeatures escri@e in t2ese uie?ines i?? @e a==?ica@?e to any ty=e oA HRSG system (==enices (, (, B, an " reAer to Sections 1 t2rou2 1 t2rou2 /
1) ReAerence Pu@?ications 1)1 #2e eitions oA t2e Ao??oin stanars, coes, an s=eciAications t2at are in eAAect at t2e time oA =u@?ication oA t2is =u@?ication s2a??, to t2e eDtent s=eciAie 2erein, Aorm a =art oA t2is =u@?ication (B!(1 Recommended Boiler Water Water Limits and Associated Steam Purity (&S$)(S!E P#" 44 Gas Turbine Heat Recovery Steam Generators Performance Test Test Code (S!E3 Boiler and Pressure Pressure Vessel Vessel Code, Code, Section $, $, Poer Boi?ers an Section *$$$, .ivision 1, 1, Pressure *esse?s (S#!4
Standards for Tubes, Samlin!, and Testin! #E!(5 Standards of t"e Tubular #$c"an!er %anufacturers Association sevent2 eition:
1)) $n aition, t2is =u@?ication ras u=on t2e orC =resente in t2e Ao??oin =u@?ications Steam& 'ts Generation and (se, Ba@cocC -i?coD "om=any, &e %r?eans, Louisiana Combustion #n!ineerin! ) A Reference Boo* on +uel Burnin! an d Steam Generation, "om@ustion Enineerin "o, $nc, StamAor, "onnecticut ( Bar'"o2en, I Ruer, an P GriAAit2, "ircumAerentia? -a?? #em=erature *ariations in Horionta? Boi?er #u@es, 'nternational ournal of %ulti"ase +lo-, *o? 9, &o 1, !assac2usetts $nstitute oA #ec2no?oy, 19;3 B + #aite? an ( E .uC?er, ( !oe? Aor Preictin F?o Reimen #ransitions in Horionta? an &ear Horionta? Gas'Liui F?o, A'CH# ournal , *o? )), &o 1, University oA Houston, January 19K/
13 .eAinition oA #erms 131 Heat recovery steam enerator HRSG: ' ( system in 2ic2 steam is enerate an may @e su=er2eate or ater 2eate @y t2e transAer oA 2eat Arom aseous =roucts oA com@ustion or ot2er 2ot =rocess A?uis
13) Firetu@e HRSG ' ( s2e?? an tu@e 2eat eDc2aner in 2ic2 steam is enerate on t2e s2e?? sie @y 2eat transAerre Arom 2ot A?ui A?oin t2rou2 t2e tu@es
133 Heat =i=e HRSG ' ( com=act 2eat eDc2aner consistin oA a =ressure vesse? an a @un?e oA 2eat =i=es #2e 2eat =i=es eDtract 2eat Arom a 2ot A?ui an trans=ort it into a =ressure vesse? 2ere steam is enerate
134 *ertica? s2e?? an tu@e atertu@e HRSG ' ( s2e?? an tu@e 2eat eDc2aner in 2ic2 steam is enerate in t2e tu@es @y 2eat transAerre Arom a 2ot A?ui on t2e s2e?? sie
135 -atertu@e ?o =ressure casin HRSG ' ( mu?ti=?e tu@e circuit 2eat eDc2aner it2in a as'containin casin in 2ic2 steam is enerate insie t2e tu@es @y 2eat transAerre Arom a 2ot as A?oin over t2e tu@es
13/ -atertu@e =i=e coi? HRSG in a =ressure vesse? ' ( tu@e or =i=e coi? circuit it2in a =ressure vesse? in 2ic2 steam is enerate insie t2e tu@es @y 2eat transAerre Arom a 2i2 tem=erature A?ui or A?uiie so?is surrounin t2e tu@e circuits
SE"#$%& ) ' F$RE#UBE HE(# RE"%*ER+ S#E(! GE&ER(#%RS )1 Genera? ( Airetu@e HRSG =rouces steam Arom @oi?er Aeeater in contact it2 t2e outsie tu@e surAace, 2i?e coo?in a 2ot A?ui 2ic2 =asses t2rou2 t2e tu@es #2e 2ot A?ui is oAten a 2i2 tem=erature as resu?tin Arom com@ustion or ot2er c2emica? reaction !oerate tem=erature ases, ?iuis, an s?urries are a?so use Hi2 tem=erature severe service Airetu@e HRSGs are su==?ie it2 @oi?er ater in su@stantia? eDcess oA t2at va=orie &atura? t2ermosi=2on: or Aorce =um=e: circu?ation systems are em=?oye Boi?er Aeeater is introuce to an over2ea steam rum, 2ic2 =rovies Aor ater storae an steam'ater se=aration in aition to t2e static 2ea rivin Aorce Aor natura? circu?ation systems Less severe service ?oer tem=erature Airetu@e HRSGs are oAten once't2rou2 nonrecircu?atin: Cett?e @oi?ers Fiures 1 an ) i??ustrate 2orionta? an vertica? units invo?vin natura? circu?ation Arom an over2ea rum Fiure 3 is a Cett?e steam enerator
)) (==?ication ))1 H$GH #E!PER(#UREH$GH FLU0 U&$#S Firetu@e HRSGs it2 2i2 tem=erature =rocess A?uis eDceein 9F: resu?tin in 2i2 @oi?in A?uD rates in eDcess oA 3, Btu =er 2our =er suare Aoot: are consiere severe service a==?ications Gas tem=eratures eDceein )F an A?uD rates to 1, Btu =er 2our =er suare Aoot can @e accommoate in Airetu@e HRSGs !ec2anica? Aeatures as escri@e in )/1 are reuire Aor t2ese severe services #2e Ao??oin =rocess a==?ications are ty=ica? oA t2ose 2ic2 oAten maCe use oA severe service Airetu@e HRSGs a Steam reAormer eAA?uent 2yroen, met2ano?, ammonia =?ants: @ Et2y?ene =?ant Aurnace eAA?uent c F?ui cata?ytic cracCer A?ue as
Su?Aur =?ant reaction Aurnace eAA?uent e "oa? asiAier eAA?uent A Su?Auric an nitric aci reaction ases #y=ica? steam'sie o=eratin =ressures rane Arom as ?o as 15 =ouns =er suare inc2 Aor A?ui cata?ytic cracCer an su?Aur =?ant a==?ications to as 2 i2 as 1; =ouns =er suare inc2 Aor ammonia an et2y?ene Aaci?ities
))) !%.ER(#E #E!PER(#UREL%- FLU0 U&$#S Firetu@e HRSGs, 2ic2 2an?e 2ot A?ui tem=eratures not eDceein 9F it2 A?uD rates oA 3, Btu =er 2our =er suare Aoot an @e?o, 2ave a ie rane o A =rocess a==?ications (ny 2ot A?ui stream it2 a tem=erature suAAicient?y a@ove t2e steam saturation tem=erature can @e uti?ie #y=ica? =rocess a==?ications inc?ue a F?ui cata?ytic cracCin unit s?urries @ !isce??aneous reAinery 2ot oi? an va=or streams c Su?Aur recovery conensers Steam'sie o=eratin =ressures rane Arom 5 =ouns =er suare inc2 to / =ouns =er suare inc2
)3 System "onsieration )31 PR%"ESS FLU$. #2e t2erma?'2yrau?ic =erAormance an mec2anica? construction oA t2e eui=ment to a ?are eree are e=enent on s=eciAic c2aracteristics oA t2e 2ot =rocess A?ui Eac2 =rocess A?ui 2as uniue as=ects 2ic2 must @e accounte Aor in t2e Airetu@e @oi?er esin to ensure re?ia@?e o=eration For eDam=?e, =rocess A?ui 2yroen content may siniAicant?y increase A?uD
)311 Fou?in Fou?in oA t2e tu@e insie surAace in Airetu@e HRSGs is ?are?y a Aunction oA t2e s=eciAic =rocess A?ui $t is a?so e=enent on ve?ocity, resience time, tu@e sie an orientation, an a?? tem=erature EDam=?es oA s=eciAic concerns inc?ue a Et2y?ene Aurnace eAA?uent uenc2 coo?ers are su@Mect to coCe e=osition ue to continuation oA t2e cracCin =rocess at e?evate tem=erature #2ereAore, 2i2 as ve?ocities resu?tin in minimum resience time at tem=erature are use @ Hyroen =?ant steam2yrocar@on reAormer eAA?uent 2eat recovery @oi?ers are su@Mect to si?ica Aou?in 2en im=ro=er reAractories are use in t2e u=stream seconary reAormer Aor ammonia Aaci?ities:, transAer ?ines, or @oi?er in?et c2anne?s c F?ui cata?ytic cracCin s?urry steam enerators are enera??y esine Aor a ve?ocity oA 5 to K Aeet =er secon to avoi sett?in out t2e so?i constituents F?ui cata?ytic cracCin A?ue as HRSGs ten to Aou? it2 cata?yst e=osits
)31) *e?ocity #2e A?ui ve?ocity insie t2e tu@es must meet certain minimum criteria Aor t2e s=eciAic =rocesses as note uner )311 #2ere are a?so maDimum ve?ocity ?imitations it2 res=ect to t2e erosive nature oA =articu?ate @earin streams $n most cases, 2oever, t2e ve?ocity is set @y maDimum =ressure ro= or @y maDimum a??oa@?e 2eat A?uD ?imits 2ic2 must @e consiere in esin
)313 Pressure .ro= Pressure ?osses across t2e tu@e sie oA a Airetu@e HRSG are ?imite @y overa?? system consierations For instance, t2e =erAormance oA an o?eAins =?ant cracCin Aurnace is
=ena?ie @y eDcessive @acC=ressure im=ose @y onstream Airetu@e uenc2 coo?ers Su?Aur recovery conensers are norma??y esine Aor =ressure ?osses oA 1 =oun =er suare inc2 or ?ess, ue to t2e ?o o=eratin =ressure ?eve?
)314 #em=erature (==roac2 #2e eree to 2ic2 t2e 2ot =rocess A?ui is reuire to a==roac2 t2e steam saturation tem=erature stron?y aAAects t2e HRSG sie #2e aroac" is eAine as t2e iAAerence @eteen t2e as out?et tem=erature an t2e saturate steam tem=erature (s t2e esin a==roac2 is reuce, t2e surAace area reuirement increases HRSGs it2 ?are a==roac2es ten to use ?arer iameter or s2orter tu@es t2an t2ose it2 c?ose a==roac2es
)315 %ut?et #em=erature "ontro? "ertain =rocess a==?ications reuire c?ose contro? oA t2e =rocess A?ui out?et tem=erature For instance, seconary reAormer eAA?uent in an ammonia =?ant enters a "% to "% s2iAt reactor aAter @ein coo?e @y t2e Airetu@e HRSG %vercoo?in @y t2e HRSG averse?y aAAects t2e s2iAt reaction cata?yst For t2is reason suc2 Airetu@e HRSGs incor=orate a 2ot as @y=ass system, 2ic2 may @e eit2er interna? or eDterna? ReAer to )/111 Aor Aurt2er construction etai?s #2e amount oA as @y=asse is a Aunction oA turnon, eDtent oA Aou?in, an t2e esin tem=erature a==roac2 #2e eui=ment tens to ov ercoo? t2e =rocess A?ui 2en run at reuce t2rou2=ut an 2en c?ean HRSGs it2 ?are esin a==roac2es ten to overcoo? ue to t2e ?are t2erma? rivin Aorce at t2e out?et en Suc2 units reuire ?are @y=ass systems Aor tem=erature contro? to 2an?e siniAicant @y=ass Aractions )
)31/ Gas .e Point Hot as streams 2ic2 may reac2 t2e e =oint oA one oA t2e as constituents reuire s=ecia? attention "onensation can occur on co? surAaces, suc2 as t2e tu@es an reAractory ?ine a??s, even t2ou2 t2e @u?C as tem=erature may @e a@ove t2e e =oint
$A @u?C as coo?in @e?o t2e e =oint occurs, as in su?Aur recovery @oi?ers, =rovision must @e mae to ensure conensate remova?
)3) B%$LER FEE.-(#ERS#E(! (==enices ( an B =rovie enera? inAormation it2 rear to t2e @oi?er Aeeatersteam system (itiona? consierations uniue to Airetu@e eui=ment are covere in )3)1 an )3))
)3)1 Heat F?uD !aDimum a??oa@?e 2eat A?uD rates Aor Airetu@e HRSGs are a Aunction oA eui=ment construction etai?s, steam =ressure, recircu?ation rates, an ater ua?ity S=eciAic construction Aeatures 2ic2 aAAect A?uD ?imits inc?ue a #u@e uantity, iameter an =itc2 in enera?, A?uD ?imits are ?oer Aor increasin tu@e uantity or ecreasin =itc2 to iameter ratio @ 7uantity, sie, an ?ocation oA risers an oncomers c "?earance @eteen @un?e an s2e?? (ctua? A?uD rates Aor com=arison it2 esin ?imits are @ase on c?ean tu@e surAace at t2e tu@e in?et 2ere t2e =rocess A?ui is t2e 2ottest Firetu@e HRSG esin s2ou? account Aor increase 2ot =rocess A?ui 2eat transAer coeAAicients ue to tu@e entrance eAAects
)3)) Boi?er -ater "ircu?ation "ritica? service 2i2 tem=erature Airetu@e HRSGs are Aurnis2e it2 e?evate steam rums, Arom 2ic2 @oi?er ater is su==?ie it2 su@stantia? eDcess recircu?ation rates Systems may @e eit2er natura? most common: or Aorce circu?ation Lo A?uD HRSGs may a?so @e Aurnis2e it2 an eDterna? rum Hoever, suc2 HRSG eui=ment more common?y maCes use oA an eD=ane s2e?? sie com=artment it2 t2e tu@e @un?e su@mere in t2e @oi?er ater vo?ume Liui isenaement occurs a@ove t2e esta@?is2e ?iui ?eve? it2in t2e eD=ane s2e?? Suc2 a unit is common?y reAerre to as a Cett?e @oi?er &atura? circu?ation =atterns occur it2in t2e Cett?e s2e?? ( ater' steam miDture rises t2rou2 t2e tu@e @un?e t2e va= or rises t2rou2 t2e steamater interAace to t2e steam s=ace a@ove an t2e @oi?er ater recircu?ates @acC on eac2 sie oA t2e @un?e to t2e @ottom oA t2e s2e?? #2e Cett?e HRSG s2e?? serves t2e =ur=oses oA a steam rum in a conventiona? @oi?er system $t iAAers Arom a conventiona? rum in t2at t2e HRSG 2eatin surAace is se?A containe, conn ections are a?tere, an steamater interna? A?o =atterns are iAAerent Saturate steam enerate in Cett?e HRSGs is norma??y use Aor =rocess or 2eatin =ur=oses For suc2 cases t2e reuirements Aor =urity an ua?ity see (==eniD (: are not 2i2 #2ereAore, se=aration is common?y ac2ieve @y eA?ector =?ates or ry =i=es ReAer to )/)4 Aor aitiona? s2e?? etai?s
)4 (vantaes oA Firetu@e %ver -atertu@e HRSGs )41 E(SE %F "LE(&$&G #u@es containin Aou?in =rone 2ot =rocess streams suc2 as o?eAins =?ant cracCin Aurnace eAA?uent, coa? asiAier over2ea, an A?ui cata?ytic cracCin A?ue as are easier to c?ean in Airetu@e HRSGs
)4) RES$.E&"E #$!E Firetu@e HRSGs 2ave ?oer =rocess A?ui vo?ume an resience time Aor services 2ere time at tem=erature is a Aactor
)43 H$GH PRESSURE %R H$GH #E!PER(#URE PR%"ESS FLU$.S %R SPE"$(L !E#(LLURG+ RE7U$RE!E&#S Hi2 =ressure =rocess A?uis containe on t2e tu@e sie may minimie HRSG ei2t #2is is =articu?ar?y @eneAicia? 2en a??oy materia?s are use For eDam=?e, ammonia converter eAA?uent can reac2 5 =ouns =er suare inc2 an reuires a??oy or c?a materia?s For t2is case a Airetu@e HRSG may @e =reAerre
)44 *$BR(#$%& Firetu@e HRSGs are ?ess susce=ti@?e to amain A?oinuce tu@e vi@ration or acoustic vi@ration 2en coo?in ?are vo?umetric A?o rate as streams
)45 REFR("#%R+ L$&$&G E?evate tem=erature as 2ic2 reuires insu?atin reAractory to avoi o ver2eatin =ressure @earin com=onents is oAten @est 2an?e in Airetu@e eui=ment #2is is =articu?ar?y true Aor =ressurie as streams, 2ic2 cannot @e 2an?e in rectanu?ar uct enc?osures ReAractory ?inin in Airetu@e HRSGs is enera??y reuire on?y in t2e in?et c2anne? com=artment $n com=arison, s2e?? an tu@e atertu@e HRSGs reuire more eDtensive reAractory ?inins, 2ic2 must @e enineere to accommoate @un?e insertion
an remova?
)4/ L%- #HR%UGHPU# (#!%SPHER$" PRESSURE FLUE G(SES Firetu@e HRSGs are @etter suite Aor incinerators an ot2er com@ustion systems =roucin re?ative?y ?o A?o rates oA A?ue as
)4K "%!P("# .ES$G& Firetu@e HRSGs norma??y reuire ?ess =?ot s=ace ue to com=act esin Horionta? Airetu@e HRSGs it2 an eDterna? steam rum can 2ave t2e rum mounte on t2e s2e?? #2e rum is su==orte @y t2e interconnectin risers an oncomers, t2ere@y e?iminatin costs associate it2 ine=enent su==ort
)5 .isavantaes oA Firetu@e Re?ative to -atertu@e HRSGs )51 H$GH #HR%UGHPU# (#!%SPHER$" PRESSURE FLUE G(SES Firetu@e HRSGs are not e?? suite Aor 2an?in ?are A?o vo?umes oA near atmos=2eric =ressure ases Streams suc2 as as tur@ine eD2aust reuire ?are cross'sectiona? A?o area as =rovie @y atertu@e coi?s insta??e in rectanu?ar uct enc?osures
)5) L%-ER HE(# #R(&SFER "%EFF$"$E&#S Heat transAer coeAAicients Aor A?o insie tu@es are enera??y ?oer t2an Aor A?o across t2e tu@e @anCs For t2is reason Airetu@e HRSGs ten to reuire more @are tu@e surAace t2an atertu@e HRSGs #2e use oA eDtene surAace Ains: aainst a ?o =ressure =rocess as can @e an eAAective means oA reucin sie #2is o=tion is oAten uti?ie in a tertu@e HRSGs, @ut is enera??y consiere im=ractica? Aor Airetu@e esins
)53 H$GH PRESSURE S#E(! (PPL$"(#$%&S For cases invo?vin 2i2 =ressure steam, ty=ica??y 15 =ouns =er suare inc2 an a@ove, Airetu@e HRSGs reuire 2eavy a?? s2e?? cy?iners an tu@es #2is is =articu?ar?y true Aor 2i2 ca=acity systems For t2is reason Airetu@e HRSGs in 2i2 =ressure steam systems ei2 more t2an t2eir atertu@e counter=arts
)54 H%# #UBESHEE# "%&S#RU"#$%& #2e 2ot tu@es2eet esin oA Airetu@e HRSGs, =articu?ar?y its attac2ment to t2e s2e?? an t2e tu@es, may @e com=?eD #2e severity oA service re?ates to t2e coeDistence oA mu?ti=?e conitions, suc2 as a Hi2 in?et as tem=erature
@ Hi2 =ressure on t2e steam sie c Loain im=ose @y t2e tu@es ue to aDia? iAAerentia? t2erma? rot2 re?ative to t2e s2e?? Potentia? erosive eAAects oA =articu?ate @earin ases e Potentia? Aor corrosive attacC Arom t2e =rocess an steam sies #2e tu@es2eet is common?y mae oA "r'!o Aerritic stee?s 2ic2 reuire s=ecia? attention urin Aa@rication an testin !any Airetu@e HRSGs reuire a t2erma? an stress ana?ysis to =rove t2e construction acce=ta@?e Aor a?? antici=ate o=eratin conitions
)/ !ec2anica? .escri=tion )/1 H$GH #E!PER(#UREH$GH FLU0 U&$#S )/11 ReAractory Line $n?et "2anne? $n?et c2anne?s oA 2i2 tem=erature units are interna??y reAractory ?ine to insu?ate t2e =ressure com=onents ( num@er oA reAractory systems are avai?a@?e, inc?uin ua? an mono?it2ic ?ayers, cast an unne, or it2 an it2out interna? ?iners *arious ty=es oA reAractory anc2orin systems are a?so use !eta??ic nee?es may @e consiere to Aurt2er reinAorce t2e casta@?e #2e se?ection oA reAractory materia?s an t2eir a==?ication met2o must @e com=ati@?e it2 t2e =rocess service conitions #2e esin must account Aor concerns suc2 as a $nsu?atin ca=a@i?ity, inc?uin eAAect oA 2yroen content on t2e reAractory t2erma? conuctivity @ "2emica? com=ati@i?ity it2 t2e =rocess A?ui c Gas e =oint re?ative to co? Aace tem=erature Erosion resistance aainst =articu?ate @earin streams e Potentia? Aor coCin uner meta??ic ?iners
)/1) "2anne?s Severa? c2anne? construction o=tions eDist #2e as connections may @e in'?ine aDia? or insta??e raia??y on a strai2t c2anne? section (ccess into t2e c2anne? com=artment is enera??y t2rou2 a manay in ?are iameter units, or t2rou2 a Au?? access cover in sma?? units
)/13 #u@es2eets #2e sin?e most istinuis2in Aeature oA 2i2 tem=erature Airetu@e HRSGs is t2e t2in tu@es2eet construction "onventiona? s2e?? an tu@e eDc2aners o=eratin at moerate tem=eratures incor=orate tu@es2eets esine accorin to t2e reuirements oA #E!( #y=ica? tu@es2eet t2icCnesses in suc2 units rane Arom ) inc2es to / inc2es or more Use oA #E!( tu@es2eets in 2i2 tem=erature 2i2 A?uD severe service: Airetu@e HRSGs is not recommene @ecause t2e tu@es2eet meta? tem=erature raient ou? @e eDcessive an 2i2 stresses ou? resu?t #2e t2in tu@es2eet esin is @ase on t2e use oA t2e tu@es as stays to =rovie t2e necessary su==ort Aor t2e tu@es2eets #u@es2eet t2icCnesses ty=ica??y rane Arom inc2 to 1 inc2es F?at =ortions oA t2e tu@es2eets it2out tu@es must @e su==orte @y su==?ementary stays SuAAicient coo?in oA t2e tu@es2eet e=ens on eAAicient 2eat transAer at t2e tu@es2eet @acCAace @y s2e?? sie va=oriation oA ater an 2i2 ?oca? circu?ation rate #2is oAAsets t2e 2eat in=ut Arom t2e as t2rou2 t2e Aront Aace an, more im=ortant?y, t2e area create @y a?? t2e tu@e 2o?e =erAorations #2e steay state tu@es2eet tem=erature is e=enent on t2e tu@e =itc2 to iameter ratio an t2e tu@es2eet t2icCness #u@es2eet tem=erature can @e Aurt2er minimie @y ?imitin 2eat A?o to t2e tu@es2eet it2 t2e use oA insu?ate Aerru?es inserte in eac2 tu@e in?et #2e Aerru?es =roMect 3 inc2es to 4 inc2es Arom t2e tu@es2eet Aace #2e s=ace @eteen t2e Aerru?es is =acCe it2 reAractory, 2ic2 secures t2e Aerru?es an insu?ates t2e tu@es2eet Aace Ferru?es are eit2er a 2i2 tem=erature resistant meta??ic or ceramic materia?, ra==e it2 an insu?atin =a=er Aor a ?i2t?y snu Ait in t2e tu@e @ore %vercom=ression oA t2e insu?ation i?? reuce its eAAectiveness Fiures 4 an 5 s2o etai?s oA one sty?e eac2 oA a meta??ic an ceramic Aerru?e %t2er conAiurations 2ave @een use
)/14 #u@e'to'#u@es2eet Joints #2e tu@e'to'tu@es2eet Moints must =rovie a =ositive sea? @eteen t2e =rocess A?ui an t2e ater'steam miDture uner a?? o=eratin conitions an t2e resu?tin =ressure an t2erma? ?oas #2e Moints must a?so it2stan transient an cyc?ic conitions #u@e'to'tu@es2eet Moints in severe service a==?ications are ty=ica??y strent2 e?e usin one oA t2e Ao??oin conAiurations a Front tu@esie: Aace e? #2e tu@es2eet may@e J'roove @eve?e see Fiure /(: or t2e tu@e may @e =roMecte Arom t2e A?at Aace, t2en e?e it2 a mu?ti=?e =ass Ai??et see Fiure /B: (itiona??y, eac2 tu@e is =ressure eD=ane t2rou2 t2e t2icCness oA t2e tu@es2eet eDce=t near t2e e? Suc2 Moints may @e use in e?evate as tem=erature a==?ications eneratin steam at =ressures to a==roDimate?y 1 =ouns =er suare inc2 @ Fu?? e=t2 e? ( ee= J'roove it2 minimum t2icCness @acCsie ?an is e?e out it2 mu?ti=?e =asses as s2on in Fiure K $A t2e ?an is consume an Ause, t2e tu@e an tu@es2eet @ecome intera? t2rou2 t2e Au?? tu@es2eet t2icCness Fu?? e=t2 e?e Moints are oAten s=eciAie Aor 2i2 tem=erature ases eneratin steam at =ressures a@ove 1 =ouns =er suare inc2 c BacC s2e?? sie: Aace e? #2is ty=e oA Moint is oAten ca??e an interna? @ore e? #2e e?in is =erAorme @y reac2in t2rou2 t2e tu@es2eet tu@e 2o?e $t 2as @een a==?ie to a ie rane oA Airetu@e HRSG o=eratin conitions, inc?uin 2i2 =ressure steam systems ( =articu?ar c2aracteristic oA t2is Moint is t2at its interity is c?ear?y veriAia@?e @y raiora=2ic eDamination ( istinct avantae oA t2e Au?? e=t2 an interna? @ore Moints is t2eir ?acC oA a crevice @eteen t2e tu@es2eet an tu@e outer surAace ( crevice, iA =resent, is su@Mect to accumu?ation oA @oi?er ater im=urities $n 2i2 tem=erature service t2e insu?atin eAAect oA a @ui?u= oA suc2 materia? can resu?t in crevice corrosion an mec2anica? Aai?ure oA t2e
Moint
)/15 #u@es2eet Peri=2era? 6nucC?e ( t2in tu@es2eet is enera??y attac2e to t2e s2e?? it2 a =eri=2era? CnucC?e @eteen t2e A?at tu@e: =ortion an t2e =oint oA attac2ment to t2e outer s2e?? see Fiure ;: #2e CnucC?e =rovies t2is critica? Moint it2 necessary A?eDi@i?ity to a@sor@ t2e aDia? iAAerentia? movement @eteen tu@es an s2e?? cause @y o=eratin tem=eratures an =ressures Pro=er esin oA t2e CnucC?e is essentia? Aor re?ia@?e o=eration oA a Airetu@e @oi?er #2e most severe cases are t2ose invo?vin e?evate tem=erature ases it2 2i2 2eat transAer rates an it2 2i2 steam sie =ressure Suc2 conitions im=ose consiera@?e ?oas on t2e CnucC?es (n eDam=?e oA a severe service a==?ication ou? @e reAormer eAA?uent in a 2yroen =?ant use to =rouce 15 =ouns =er suare inc2 steam EDam=?es oA ?ess severe services inc?ue A?ui cata?ytic cracCin A?ue as an su?Aur recovery =?ant tai? as 2ere conensers enerate steam at / =ouns =er suare inc2 an @e?o
)/1/ "2anne?'#u@es2eet'S2e?? $nterconnection &umerous conAiurations are avai?a@?e Aor t2e interconnection oA t2e t2in tu@es2eet it2 t2e HRSG s2e?? an t2e as in?et c2anne? Fiures ;( t2rou2 ;H i??ustrate a num@er oA t2ese Se?ection e=ens on Aactors suc2 as a EDtent oA tu@e versus s2e?? iAAerentia? t2erma? rot2 @ Steam =ressure c Process as =ressure !ateria?s oA construction e *ertica? versus 2orionta? HRSG orientation Joints s2on in Fiures ;( an ;B are use Aor mi? services on?y, ue to t2e Ai??et e? attac2ment an accom=anyin crevice Fiures ;" t2rou2 ;F a?? 2ave @utt e?e attac2ment to t2e s2e?? #2e A?ane construction oA Fiure ;F =ermits c2anne? remova? Fiure ;G is use Aor 2i2 =ressure steam service an Fiure ;H is e??'suite Aor vertica??y insta??e units
)/1K #u@es2eet -it2out Peri=2era? 6nucC?e "onAiuration ( =ro=rietary Airetu@e HRSG esin uti?ies a stiAAene t2in tu@es2eet 2ic2 e?iminates t2e =eri=2era? CnucC?e Rat2er t2an re?ievin t2e tu@e aDia? ?oas it2 A?eDi@?e CnucC?es, t2e ?oas are transmitte irect?y to t2e HRSG s2e?? t2rou2 a stiAAenin system 2ic2 @acCs u= t2e t2in tu@es2eet #2is esin may =ermit t2e use oA ?oner tu@es #2e iAAerentia? movement a@sor@e @y t2e CnucC?es oA a conventiona? Airetu@e HRSG tu@es2eet is =ro=ortiona? to t2e tu@e ?ent2 For suc2 HRSGs a ?ent2 ?imit eDists, @eyon 2ic2 t2e CnucC?es ou? @e inca=a@?e oA acce=tin t2e im=ose ?oas it2in stress ?imits oA t2e materia?
)/1; .ua? "om=artment Firetu@e HRSGs #2e ?ent2 ?imitation escri@e in )/1K is oA siniAicant concern =rimari?y it2 2i2 tem=erature, 2i2 A?uD, 2i2 steam =ressure eui=ment For suc2 cases t2e o=tion eDists to use ua? com=artment construction #o Airetu@e HRSGs, eac2 it2 conventiona? CnucC?e tu@es2eets, are insta??e in series, as s2on @y Fiure 9 #2e to com=artments may @e serve @y a common steam rum (vantaes oA t2is conAiuration inc?ue a Reuces iAAerentia? rot2 @eteen s2e?? an tu@es it2in eac2 com=artment @ Permits o=timiation oA 2eat transAer surAace t2rou2 uti?iation oA iAAerent tu@e iameters an ?ent2s in eac2 com=artment, t2ere@y reucin t2e tota? surAace reuire
c Permits ?ocatin t2e interna? @y=ass system in t2e secon com=artment, t2ere@y su@Mectin t2e contro? com=onents to ?ess severe tem=erature conitions
)/19 #u@es #y=ica? tu@e iameters in 2i2 tem=erature Airetu@e HRSGs rane Arom 1)5 inc2es to 4 inc2es Use oA re?ative?y ?are tu@es =ermits t2e Ao??oin a Lo =ressure ro= a==?ication ty=ica? oA ?o =ressure =rocess as streams suc2 as tai? as oA su?Aur recovery =?ants @ #2erma? esin at ?oer 2eat A?uDes c $nsta??ation oA tu@e in?et Aerru?es it2out over'restrictin t2e A?o area avai?a@?e at eac2 tu@e entrance Limits t2e =otentia? Aor =?uin tu@es in services =rone to Aou?in #2e minimum tu@e a?? t2icCness is overne @y a==?ica@?e coe ru?es EDce=t Aor cases invo?vin very 2i2 =rocess as =ressures, t2e steam =ressure 2ic2 acts eDterna??y enera??y contro?s t2e minimum tu@e t2icCness
)/11 #u@e (rranement an S=acin #u@es are norma??y arrane on a trianu?ar =attern, a?t2ou2 suare ?ayouts may a?so @e use #2e se?ection oA tu@e =itc2 s2ou? aress t2e Ao??oin concerns a #2e maDimum a??oe 2eat A?uD is a Aunction oA t2e tu@e =itc2 to iameter ratio .ecreasin t2e =itc2 to iameter ratio reuces t2e a??oa@?e esin A?uD @ #2e tu@es2eet meta? tem=erature is a?so e=enent on t2e tu@e =itc2 .ecreasin t2e =itc2 increases t2e meta? tem=erature
c ( minimum tu@es2eet ?iament it2 @eteen aMacent tu@es is reuire Aor e?e tu@e ens to =2ysica??y accommoate t2e tu@es2eet J'roove e? =re=arations #2is is =articu?ar?y siniAicant Aor Au?? e=t2 e?e Moints
)/111 !u?ti=?e #u@e Passes !ost 2i2 tem=erature =rocess Airetu@e HRSGs are oA sin?e tu@e =ass con struction Hoever, mu?ti=?e =ass tu@es may @e consiere Aor =rocesses invo?vin near atmos=2eric =ressure ases use to enerate ?o =ressure steam #2e ?o 2eat transAer coeAAicients c2aracteristica??y associate it2 suc2 ases resu?t in tu@e meta? tem=eratures 2ic2 very c?ose?y a==roac2 t2e steam saturation tem=erature #2ereAore, t2e meta? tem=erature iAAerence an iAAerentia? t2erma? rot2 oA tu@es oA iAAerent =asses are minima? Hot =ass tu@es are ty=ica??y ?arer iameter t2an su@seuent =asses in orer to o=timie 2eat transAer it2in =ressure ro= constraints Fiure 1 i??ustrates a to tu@e =ass 2i2 tem=erature Airetu@e steam enerator
)/11) Gas By=ass Systems Gas @y=ass systems Aor @oi?er out?et tem=erature contro? may @e eDterna? or interna? to t2e @oi?er $nterna? @y=asses are common?y use @ecause t2ey taCe a vantae oA coo?in t2e @y=ass =i=e it2 @oi?er ater #2e =i=e may @e interna??y insu?ate to ensure t2at t2e meta? tem=erature is maintaine c?ose to t2e ater tem=erature $n 2i2 steam =ressure
a==?ications t2e =i=e may @e attac2e to a transition CnucC?e in eac2 tu@es2eet to a@sor@ aDia? ?oas #2e =i=e is ?ocate in t2e center oA t2e tu@e ?ayout to =rovie Aor aDisymmetric istri@ution oA ?oas (n automatica??y contro??e va?ve is Aurnis2e at t2e out?et en oA t2e as @y=ass =i=e #o reuce t2e sie oA t2e =i=e an va?ve an to increase t2e A?o contro? rane, a =?ate it2 aMusta@?e am=ers may @e insta??e in t2e out?et c2anne? By settin t2e am=ers to a more c?ose =osition, t2e aitiona? =ressure ro= im=arte to t2e main as stream encouraes A?o t2rou2 t2e @y=ass #2e ou t?et c2anne? s2ou? @e reAractory ?ine or =rovie it2 interna?s to =rec?ue t2e =ossi@i?ity oA im=inement oA 2ot @y=ass as on t2e c2anne? a?? ( ty=ica? interna? @y=ass system is s2on in Fiure 11 %t2er systems are avai?a@?e
)/113 Risers an .oncomers (euate uantity, sie, an =ro=er ?ocation oA risers an oncomers are essentia? Aor re?ia@?e o=eration oA 2i2 tem=erature, 2i2 A?uD Airetu@e HRSGs Settin t2e steam rum e?evation, siin t2e interconnectin circu?ation =i=in, an =ositionin t2e connections are an intera? =art oA t2e esin Riser an oncomer esin an connection =ositionin e=en on @oi?er orientation Horionta? Airetu@e HRSGs are usua??y Aurnis2e it2 mu?ti=?e risers an oncomers "onnections are =ositione to serve ones oA eua? steam eneratin ca=acity For sin?e =ass @oi?ers t2e connections ten to @e more c?ose?y s=ace at t2e 2ot en (t ?east one riser an oncomer =air s2ou? @e ?ocate as c?ose as =ossi@?e to t2e 2ot tu@es2eet
*ertica? units 2ave one or more oncomer connections ?ocate at t2e @ottom oA t2e @oi?er s2e?? %A reater siniAicance, 2oever, is t2e construction at t2e to= 2ic2 must ensure am=?e an continuous ettin oA t2e entire s2e?? sie Aace oA t2e tu@es2eet #2e Ao??oin construction o=tions may @e consiere to 2e?= avoi va=or @?anCetin @eneat2 t2e u==er tu@es2eet a !u?ti=?e riser connections insta??e aroun t2e Au?? circumAerence as 2i2 on t2e s2e?? as =ossi@?e @ Reverse CnucC?e tu@es2eets to =ermit Aurt2er e?evation oA t2e riser connections re?ative to t2e tu@es2eet ReAer to Fiure ;H c S=ecia? @aAA?in uner t2e tu@es2eet to irect ater across t2e @acC Aace oA t2e tu@es2eet S=ecia? Aorme or mac2ine u==er tu@es2eet it2 a s?i2t ta=er Arom t2e center u=ar to t2e =eri=2ery e $nsta??ation oA t2e entire @oi?er s?i2t?y cante Arom true vertica? so t2at t2e tu@es2eet s?o=es s?i2t?y u=ar toar t2e risers 2ic2 are ?ocate on t2at sie
)/) 6E##LE S#E(! GE&ER(#%RS 6ett?e steam enerators are 2orionta??y insta??e units it2 an en?are s2e?? sie @oi?in com=artment iameter re?ative to t2e tu@e @un?e #2e @un?e =enetrates t2rou2 eit2er a =ort o=enin in a conventiona? 2ea, or t2e sma?? en oA an eccentric conica? transition #2e ?atter esin is more common
)/)1 #u@e Bun?e "onstruction #u@e @un?es may @e remova@?e or AiDe Remova@?e @un?es oAAer certain avantaes #2e @un?e may @e remove Aor ins=ection, c?eanin, re=air, or re=?acement (?so, remova@?e @un?es avoi t2e iAAerentia? aDia? t2erma? eD=ansion stress 2ic2 occurs in
AiDe tu@es2eet esins Remova@?e @un?es may @e oA eit2er U'tu@e or A?oatin 2ea construction For A?uis =rone to Aou?in or erosive =rocess A?uis t2at may reuire mec2anica? c?eanin or ins=ection, t2e A?oatin 2ea ty=e is =reAerre
)/)) #u@e Sie, (rranement, an &um@er oA Passes #y=ica? tu@e iameters are inc2 an 1 inc2, a?t2ou2 ?arer sies are consiere Aor 2i2?y =rone to Aou?in or viscous =rocess A?uis suc2 as in su?Aur conensers #u@es are arrane on eit2er a suare or trianu?ar =attern #2e suare arranement is use iA c?eanin oA t2e outsie tu@e surAace is antici=ate, as cou? @e t2e case Aor eneratin ?o =ressure steam Arom =oor ua?ity @oi?er ater $n suc2 cases inc2 minimum it2 c?eanin ?anes are maintaine @eteen tu@es %t2erise, a =itc2 to iameter ratio oA 1)5 is norma??y use, un?ess 2eat A?uD consierations reuire a more eDtene s=acin !u?ti=?e tu@e =asses may @e use Aor a?? @un?e ty=es escri@e in )/)1, eDce=t Aor cases it2 eDtreme?y ?on 2ot A?ui coo?in ranes 2ic2 may eD=erience severe t2erma? stress Sin?e =ass tu@es are @asica??y ?imite to AiDe tu@es2eet construction
)/)3 "2anne? "onstruction #2e se?ection e=ens =rimari?y on t2e antici=ate Areuency oA o=enin t2e unit Aor ins=ection or c?eanin $A Areuent access is reuire, a c2anne? it2 @o?te cover =?ate is esira@?e "2anne?s may @e any oA t2e #E!( esinate ty=es
)/)4 S2e?? "onstruction Aor .e'Entrainment ( eree oA isenaement oA ?iui is ac2ieve in t2e steam s=ace a@ove t2e ?iui ?eve? #2e eAAectiveness oA t2is vo?ume is a Aunction oA t2e Aree 2ei2t avai?a@?e ( ty=ica? minimum 2ei2t is ) inc2es in steam eneratin eui=ment Units 2ic2 =rouce very ?o =ressure steam or o=erate at re?ative?y 2i2 A?uD ten to nee aitiona? 2ei2t Sim=?e ry =i=e evices are sometimes use to en2ance se=aration ( =ro=er?y sie Cett?e s2e?? =rouces steam oA aeuate ua?ity or =urity Aor most =rocess an 2eatin a==?ications Hi2er =urity steam may @e ac2ieve @y t2e insta??ation oA se=arators in t2e va=or s=ace a@ove t2e ?iui ?eve?, it2in a ome e?e to t2e to= oA t2e Cett?e, or in t2e eDit va=or ?ine #y=es oA se=arators inc?ue
a -ire mes2 =as @ "2evrons c "yc?ones "om@inations oA $tems a, @, an c ReAer to (==eniD ( Aor Aurt2er inAormation
)/3 %#HER #+PES %F F$RE#UBE HRSGS #2ere are many ot2er ty=es oA Airetu@e HRSGs esine Aor a variety oA services #2ey may @e Aurt2er c?assiAie as Ao??os a Pro=rietary esins eve?o=e Aor s=eciAic =rocess a==?ications @ Boi?ers esine it2 #E!( tu@es2eets an eDterna? rums #2e @oi?ers may @e insta??e in t2e 2orionta? or vertica? =osition c Partia??y tu@e 2orionta??y insta??e @oi?ers as s2on in Fiure 1) #u@es omitte Arom t2e to= =ortion oA t2e tu@es2eets =rovie t2e steam s=ace Aor interna? isenaement #2e c2anne? iameter is ?arer an t2e s2e?? iameter is sma??er t2an t2ose oA Cett?e HRSGs #u@es2eets may @e #E!(, or staye t2in
)/4 "%.E "%&S$.ER(#$%&S Firetu@e HRSGs are esine in accorance it2 eit2er (S!E Boiler and Pressure Vessel Code, Section 1 or Section *$$$, .ivision 1 Heavy tu@es2eet Airetu@e HRSGs are norma??y esine to #E!( reuirements (B!( uie?ines are common?y Ao??oe Aor @oi?er Aeeater treatment, a??oa@?e concentration oA @oi?er ater isso?ve so?is, @?oon, an steam =urity
)/5 "%&S#RU"#$%& !(#ER$(LS !ateria?s se?ecte Aor use in Airetu@e HRSGs must @e com=ati@?e it2 t2e = rocess A?ui, t2e @oi?er ater, an steam it2 2ic2 t2ey i?? come into contact #2e materia?s must a?so eD2i@it mec2anica? =ro=erties consistent it2 t2e esin reuirements oA t2e eui=ment
)/51 "orrosion Resistance Eac2 =rocess A?ui Arom 2ic2 2eat is @ein recovere 2as its on com=osition an may t2ereAore 2ave its on uniue reuirements Aor construction materia?s (n im=ortant Aactor in materia?s se?ection is oAten resistance to 2yroen attacC, @ecause many 2i2
tem=erature =rocess as streams 2ave siniAicant 2yroen content #2e s=eciAication oA materia?s must a?so account Aor t2e =ossi@i?ity oA as coo?in @e?o its e =oint, an t2e corrosive acis 2ic2 may @e Aorme "o? meta? surAaces can cause ?oca? conensation, even t2ou2 t2e @u?C as may @e a@ove t2e e =oint Pressure com=onents ette @y @oi?er ater, inc?uin tu@es an tu@es2eets, are norma??y Aa@ricate Arom Aerritic materia?s Boi?er s2e??s are enera??y car@on stee? !ateria?s su@Mect to stress corrosion cracCin, suc2 as austenitic stain?ess stee?s, are norma??y avoie an are =ro2i@ite in t2e eva=orator @y (S!E Boiler and Pressure Vessel Code, Section 1 #2e re?ative rot2 oA t2e s2e?? an tu@es ue to tem=erature c2anes is oA consiera@?e siniAicance to Airetu@e HRSG esin !ateria?s it2 simi?ar coeAAicients oA t2erma? eD=ansion are @eneAicia? #2is is anot2er reason Aor avoiin t2e use oA austenitic tu@in
)K %=erations .escri=tion SaAe an re?ia@?e o=eration oA Airetu@e HRSGs e=ens on t2e eve?o=ment an use oA oo o=eratin =roceures, s=eciAic to t2e =rocess an HRSG esin
)K1 PR%"ESS S$.E %PER(#$%& )K11 &e reAractory ?inin may reuire a s=ecia? 2eatin seuence on start'u= to eAAect =ro=er ryout
)K1) Firetu@e HRSGs must not @e su@Mecte to 2ot as A?o un?ess t2e tu@e @un?e is Au??y covere @y @oi?er Aeeater
)K13 #2e rate oA tem=erature c2ane urin transients s2ou? @e contro??e to minimie t2e =otentia? Aor t2erma? s2ocC
)K14 (?? moes oA o=eration s2ou? @e eva?uate urin t2e esin =2ase, =articu?ar?y it2 rear to t2e a@i?ity oA t2e @oi?er com=onents to it2stan t2e =rimary an seconary stresses urin cyc?ic o=eration
)K) S#E(! S$.E %PER(#$&G "%&"ER&S )K)1 Re?ia@i?ity oA Boi?er Feeater Su==?y %A =rimary im=ortance to t2e successAu? o=eration oA Airetu@e HRSGs is t2e re?ia@?e su==?y oA @oi?er ater to t2e 2eat transAer surAace $n t2e event oA @oi?er Aee ater su==?y Aai?ure, t2e contro? system must s2ut oAA t2e 2ot stream A?o to t2e HRSG ReAer to (==eniD ( Aor Aurt2er inAormation
)K)) Boi?er Feeater #reatment Boi?er Aeeater c2emica? treatment must =rotect @oi?er com=onents Arom ater sie corrosion $m=ro=er treatment, or u=sets, may cause =remature Aai?ure -ater treatment s=ecia?ists are norma??y consu?te
)K)3 "ontinuous B?oon B?oon oA @oi?er ater must @e use in conMunction it2 @oi?er Aeeater treatment to ensure t2at @oi?er ater im=urities are maintaine at or @e?o recommene maDimum concentration "ontinuous surAace @?oon may @e accom=?is2e t2rou2 a =erAorate co??ector =i=e ?ocate Must @e?o t2e ater'steam interAace or a conn ection at t2e s2e?? @ottom "ontinuous @?oon Arom Cett?e HRSGs s2ou? @e eDtracte =rimari?y Arom t2e en o==osite t2e Aeeater in?et 2ere im=urities ou? @e most concentrate
)K)4 $ntermittent B?oon $ntermittent @?oon acts to remove sett?e accumu?ations oA @oi?er ater so?is "onnections are ?ocate at ?o =oints in t2e s2e??, =articu?ar?y in t2e most stanant reions B?oon va?ves are o=erate at =rescri@e interva?s, e=enin on t2e eAAectiveness oA @oi?er ater treatment
)K)5 Liui Leve? in 6ett?es #2ere is no c?ear?y eAine ater'steam interAace insie t2e s2e?? Steam @u@ @?es rise viorous?y t2rou2 t2e ater Arom t2e 2eat transAer surAaces ( ensity iAAerence eDists @eteen t2e to =2ase miDture in t2e @oi?er s2e?? an t2e ?iui in an eDterna? ae ?ass #o ensure su@mere tu@es, t2e ater ?eve? is norma??y maintaine at ) inc2es to 4 inc2es a@ove t2e to= oA t2e u==ermost tu@e ro
SE"#$%& 3 ' *ER#$"(L SHELL#UBE -(#ER#UBE HRSGs 31 Genera? 311 ( vertica? s2e??tu@e atertu@e HRSG is a vertica? tu@e'@un?e 2eat eDc2aner 2ere steam is enerate insie tu@es @y a s2e??'sie 2ot A?ui
31) F?oatin 2ea, U'tu@e, or @ayonet an sca@@ar tu@e construction are ty=es oA vertica? s2e??tu@e atertu@e HRSGs See 35, Fiures 13 an 14 are ty=ica? A?oatin 2ea an @ayonetsca@@ar ty=es oA vertica? s2e??tu@e atertu@e HRSGs %t2er conAiurations may @e use
313 Hot A?ui can enter t2e s2e?? Arom eit2er t2e to= or t2e @ottom #2e s2e?? is usua??y a one =ass s2e?? #E!( ty=e E arranement #2e steamater sie is a one =ass system t2rou2 t2e tu@e @un?e or a to =ass system t2rou2 t2e U'tu@e an @ayonetsca@@ar esins
314 #2e vertica? s2e??tu@e atertu@e HRSG can @ e eit2er natura? circu?ation t2ermosi=2on: or Aorce circu?ation =um=e: #2e U'tu@e arranement is a?ays Aorce circu?ation For eit2er A?o arranement, t2e to =2ase steamater miDture is se=arate in a steam rum #2e se=arate ater is recircu?ate @acC to t2e tu@es -ei2t =ercent oA steam enerate ranes Arom a@out 5 =ercent to a@out ) =ercent oA t2e tota? ater circu?ate ReAer to (==enices ( an B Aor steam rum an circu?ation consierations
3) (==?ication 3)1 *ertica? s2e??tu@e atertu@e HRSGs are ty=ica??y use to enerate steam Arom 2yrocar@on ases or ?iuis, cata?yst'?aen A?ue ases, an viscous =rocess A?uis *ertica? s2e??tu@e atertu@e HRSGs are enera??y suita@?e Aor eit2er c?ean or Aou?in s2e??'sie A?uis Hi2?y Aou?in or very irty A?uis, 2oever, may @e @etter suite Aor tu@e'sie esins since t2ese ty=es are more easi?y c?eane #o Aaci?itate c?eanin t2e s2e??'sie oA @un?es in Aou?in or irty service, use remova@?e tu@e @un?es it2 suare or rotate suare =itc2 an inc2 minimum c?eanin ?anes S2e??'sie ve?ocities a@ove 1 Aoot =er secon are =reAerre to minimie Aou?in #o avoi ?aminar A?o an ?o 2eat transAer coeAAicients, vertica? s2e??tu@e atertu@e HRSGs are use 2ere t2e s2e??'sie A?ui viscosity eDcees 1 centi=oise
3)) (ny =ressure steam may @e enerate, @ut t2ese HRSGs are =articu?ar?y suita@?e Aor 2i2 steam =ressures
33 System "onsieration 331 For natura? circu?ation, t2e steam rum must @e 2i2er t2an t2e to= tu@e o=enin oA any oA t2e steam eneratin tu@es
33) Hi2 =urity ater is =articu?ar?y im=ortant Aor t2e ?on'term o=eration an re?ia@i?ity oA @ayonetsca@@ar esins .e=osits in @ayonetsca@@ar esins mi2t insu?ate t2e ti=s oA t2e tu@es causin over2eatin an Aai?ure U'tu@es are a?so sensitive to e=osits @ecause oA iAAicu?ty in c?eanin See #a@?e ('1 Aor @oi?er ater ua?ity an associate steam =urity
333 *ertica? s2e??tu@e atertu@e HRSGs may ei2 ?ess t2an Aire tu@e esins EDam=?es are esins 2ere steam =ressure is 15 =ouns =er suare inc2 or reater an t2e =rocess 2ot stream is / =ouns =er suare inc2 or ?oer (P$ Recommene Practice 5)1 reuires t2at t2e ?o =ressure sie esin @e raise to to't2irs t2e 2i2 =ressure sie esin =ressure to =rotect aainst tu@e ru=ture (s an a?ternative to esinin t2e s2e?? sie Aor to't2irs t2e 2i2 =ressure sie esin, t2e s2e?? can @e =rotecte aainst over=ressuriation @y a re?ieA va?ve #2e s2e?? sie esin =ressure can t2en @e @ase on t2e =rocess stream conitions #2e ?oer esin =ressure resu?ts in ?oer s2e?? ei2t
334 S=ecia? Aeatures are reuire in esin or o=eration to =rotect t2e HRSG in event oA ater Aai?ure
335 #2e tu@e sie oA U'tu@e @un?es are iAAicu?t to c?ean via roin aroun t2e U'@ens #2e tu@es are susce=ti@?e to sca?e, e=osits, an e@ris @ecause oA t2e sma?? insie tu@e iameter an orientation oA t2e tu@es Suc2 e@ris may co??ect at t2e ?o =oint in t2e U'
@en .oncomer strainers may @e insta??e to minimie tu@e =?uin Arom ?are
Aorein o@Mects Bayonet tu@e esins 2ave a restrictive annu?us @eteen t2e tu@es #2is reuires eDtra care in Cee=in e@ris out oA t2e system 2ic2 cou? @?ocC A?o to a tu@e ( strainer is enera??y reuire in t2e ater su==?y =i=in at t2e steam enerator entrance in t2ese cases
34 (vantaes oA *ertica? S2e??#u@e -atertu@e %ver Firetu@e HRSGs 341 *ertica? s2e??tu@e atertu@e HRSGs can @e esine Aor 2i2er maDimum 2eat A?uD t2an Airetu@e HRSGs since A?o istri@ution an steam eneration are more uniAorm See #a@?e B'1 Aor 2eat A?uD com=arison oA atertu@e HRSGs versus Airetu@e HRSGs
34)
$A mu?ti=?e risers are reuire, t2ey can eac2 @e arrane to 2ave t2e same =ro=ortion oA tota? A?o $n 2i2 =ressure systems, eua? A?o in eac2 riser =rovies more uniAorm istri@ution to Aaci?itate @etter =erAormance oA t2e steam rum
343 #2e tu@e @un?e is Aree to eD=an so stresses Arom iAAerentia? eD=ansion @eteen t2e tu@es an s2e?? are not ?are #2is is =articu?ar?y true oA t2e @ay onet tu@e esin 2ere eac2 tu@e can eD=an ine=enent?y it2out inucin tu@es2eet stresses Arom iAAerentia? eD=ansion @eteen aMacent tu@es
344 #2e vertica? s2e??tu@e atertu@e HRSG reuires no reAractory ?inin oA t2e tu@e sie c2anne? or A?oatin 2ea tu@es2eet Aace $n t2e event oA a sin?e =ass @are tu@e Aai?ure, no reAractory 2as to @e remove to re=air t2e Aai?e tu@e
345
$A U'tu@e an @ayonet tu@e esins 2ave tu@es2eets at t2e out?et co? en: oA t2e s2e??, t2e tu@es2eets can @e esine it2 ?oer a??oy meta??ury t2an 2en ?ocate at t2e in?et or 2ot en oA t2e s2e??
34/ $n t2e event oA tu@e Aai?ure Aor @ayonet tu@e units, t2e @ayonet tu@e @un?e an tu@es2eet can @e remove to access t2e sca@@ar tu@e or tu@es t2at Aai?e
34K S=are tu@e @un?es i?? ena@?e uicC turnaroun since t2e amae @un?e can @e uicC?y =u??e an t2e s=are @un?e insta??e to a??o t2e unit to @e =ut @acC on stream
35 !ec2anica? .escri=tion 351 FL%(#$&G HE(. #2e @ottom tu@es2eet is a A?oatin 2ea conAiuration it2 a no?e t2at =asses Arom t2e A?oatin 2ea t2rou2 t2e s2e?? 2ea to a??o ater to @e Ae Arom t2e @ottom #2e Aee ater is 2eate an @ecomes a to'=2ase miDture as it =asses t2rou2 t2e 2eate one an enters t2e to= c2anne? (Ater one =ass t2rou2 t2e eDc2aner, t2e steamater enters a steam rum #2e 2ot A?ui may @e concurrent or countercurrent on t2e s2e?? sie (n eD=ansion Moint in t2e A?oatin 2ea in?et no?e an t2e A?oatin 2ea are =rovie to com=ensate Aor t2erma? eD=ansion @eteen s2e?? an tu@e
35) F$0E. #UBESHEE# #2e s2e?? oA t2e 2eat eDc2aner may contain an eD=ansion Moint to a??o Aor iAAerentia? t2erma? rot2 @eteen t2e tu@es an t2e s2e??
353 U'#UBES ( U'tu@e vertica? s2e??tu@e atertu@e HRSG consists oA a vertica? s2e?? it2 a c2anne? at t2e to= $nsie is a traitiona? U'tu@e @un?e -ater enters t2e c2anne?, A?os on t2e in?et ?e an u= t2e out?et ?e oA t2e U'tu@e #2e 2eatin A?ui A?os u= or on t2rou2 t2e @un?e s2e?? sie #2e U'tu@e @un?e is Aree to move in res=onse to t2erma? rot2 an is not aAAecte @y t2e s2e?? t2erma? rot2
354 B(+%&E# #UBES #2e @ayonet vertica? s2e??tu@e atertu@e HRSG em=?oys a set oA concentric tu@es #2e sma??er iameter tu@e is ca??e t2e @ayonet, an t2e ?arer iameter tu@e is ca??e t2e sca@@ar #2e sca@@ar tu@e =attern may @e a stanar trianu?ar or suare =itc2 Eac2 sca@@ar tu@e is inserte t2rou2 to tu@es2eet 2o?es an attac2e #2e en oA t2e
sca@@ar tu@e is ca==e #2e @ayonet tu@e an tu@es2eet =attern are ientica? to t2e sca@@ar =attern #2e @ayonet tu@es are attac2e to t2is tu@es2eet an are not ca==e #2e to @un?es are assem@?e so t2at eac2 @ayonet is inserte into its corres=onin sca@@ar #2e tu@es2eets are se=arate aDia??y @y a c2anne? s=acer =iece ReAer to Fiure 14
3/ %=erations .escri=tion #2e @oi?er Aee ater enters t2e @ayonet c2anne? com=artment, A?os on t2rou2 t2e @ayonets, u= t2e sca@@ar annu?us to t2e ?oer c2anne? com=artment, an t2en out into a steamater riser #2e ou@?e c2anne? @un?e is inserte into a vertica? A?ane s2e?? #2e =rocess 2eatin stream enters t2e s2e?? at t2e @ottom @e?o t2e ens oA t2e sca@@ar @un?e an A?os u= t2rou2 t2e @un?e, eDitin t2e s2e?? at t2e to= Must @eneat2 t2e sca@@ar @un?e tu@es2eets
SE"#$%& 4 ' -(#ER#UBE "%$LS $&S$.E PRESSURE *ESSELS 41 Genera? 411 -atertu@e coi?s may @e ?ocate eit2er 2orionta??y or vertica??y insie a vesse? #2e vesse? contents are t2e 2eat source Fiure 15 s2os a 2orionta? arranement
41) #2e coi?s are su==orte insie t2e vesse? at severa? =ara??e? ?eve?s
413 #2e coi?s may @e Aa@ricate oA eit2er =i=e or tu@in
4) (==?ication ( ty=ica? eDam=?e is a cat'cracCer cata?yst reenerator eui==e it2 a A?uiie @e oA cata?yst at 13F to 14F #2is cata?yst is a ?are source oA 2eat to enerate steam it2in t2e coi?s:
43 System "onsieration 431 Freuent?y t2e coi?s are esine it2 mu?ti=?e tu@e sie A?o =asses $n t2ese cases, t2e cross'section A?o area, t2e 2eat transAer surAace area oA eac2 =ass, an t2e ater A?o
rate to eac2 =ass s2ou? @e ientica? .esin in?et A?o ve?ocity in eac2 =ass s2ou? @e in t2e rane oA 3 to K Aeet =er secon
43) #2e 2eat transAer =arameters, suc2 as transAer rate, circu?ation ratio, an s=eciAic A?o rate, must @e se?ecte to ensure nuc?eate @oi?in
433 #2e esin oA t2e coi?s is uite critica? "onservative =ractice ictates careAu? c2oice oA coi? insie iameter, ?ent2, an 2eat A?uD to arrive at a satisAactory an o=era@?e system to avoi Ai?m @oi?in, va=or ?ocC, or unsta@?e A?o conitions .urin =rocess u=sets, suc2 as cessation oA @e A?uiiation or circu?ation, ?oss oA steam eneration may occur in one or more oA t2e iniviua? =ara??e? =asses #2e system esin s2a?? consier t2is =ossi@i?ity
434 Force circu?ation is recommene to ensure a AiDe A?o rate to eac2 coi? it2 a minimum circu?ation ratio oA 51
435 (n annu?ar A?o reime is esire $A annu?ar A?o cannot @e ac2ieve, s=ecia? inserts may @e insta??e to ensure ette a??s
43/ #2e system s2a?? @e esine it2 t2e ater sie =ressure a?ays @ein reater t2an t2e s2e?? sie =ressure
43K (==?ications may eDist 2ere A?o measurement or contro? may @e reuire on iniviua? ater sie =asses oA mu?ti=ass coi?s $so?ation oA iniviua? =asses may @e consiere, a?t2ou2 t2e ?oss oA coo?in may amae t2e coi?
44 !ec2anica? .escri=tion #2e coi? s2a?? @e esine to meet t2e reuirements oA t2e a==?ica@?e (S!E coe #2erma? stresses an mec2anica? ?oas must @e consiere in esinin t2e coi?s
45 %=erations .escri=tion
451 Pro=er rum ater treatment must @e eDercise to a voi 2avin ater sie e=osits Suc2 e=osits ou? ?ea to 2i2 tu@e meta? tem=eratures, ?oss oA t2erma? eAAiciency, an u?timate tu@e Aai?ure -ater sie e=osits may a?so ?ea to =ossi@?e =um= Aai?ure -2ere severa? =ara??e? steam eneration coi?s are reuire to maCe u= a tota? steam rate, a careAu? c2oice oA contro? va?ve ?ocation is necessary to ensure @a?ance A?o Since t2e 2eat transAer environment in 2ic2 t2e steam e neratin coi?s are ?ocate is a severe service, oriAices @a?ance A?o at t2e in?et oA eac2 =ara??e? coi? "ontro? va?ves must @e =rovie t2ere a?so to s2ut on s=eciAic coi?s in t2e event oA a @reaC or ?eaC Arom t2e coi?
45) Pressure re?ievin evices may @e reuire on t2e vesse? to =rotect t2e vesse? in t2e event oA coi? Aai?ure
SE"#$%& 5 ' -(#ER#UBE L%- PRESSURE "(S$&G HRSG 51 Genera?
511 #+P$"(L S+S#E! #2e atertu@e ?o =ressure casin HRSG enerates steam insie a num@er oA tu@e circuits t2at are 2eate @y a 2ot as stream A?oin t2rou2 an enc?osure oA insu?ate stee? casin =?ate #2e as norma??y A?os across t2e tu@es in a sin?e =ass Arom in?et to out?et $n certain cases, @aAA?es or irectiona? vanes may @e use to irect t2e as across t2e tu@es creatin aitiona? as =asses Steam eneratin tu@es are connecte to rums or 2eaers #2e tu@es may @e arrane in one continuous circuit or may @e maniAo?e at t2eir in?et an out?et ens to Aorm a num@er oA =ara??e? A?o =at2s Steam rums may @e eit2er intera? to t2e steam eneratin tu@e circuit or mounte remote?y Arom t2e tu@es (itiona? tu@e circuits may @e use Aor =re2eatin Aeeater or su=er2eatin steam
5) (==?ication #2e atertu@e ?o =ressure casin HRSG is use to recover 2eat Arom ?o =ressure eD2aust or A?ue ases Some common a==?ications are a Heat recovery Arom com@ustion tur@ine eD2aust as to =rouce steam Aor use in =rocesses:, in en2ance oi? recovery, an in coeneration @ Heat recovery Arom Aire 2eater A?ue as to =rouce steam c Heat recovery Arom A?ui cata?ytic cracCin reenerator A?ue as to =rouce =rocess steam #2e casin s2a?? @e esine it2 ti2t Moints, =reAera@?y sea? e?e, to =revent as ?eaCs to t2e atmos=2ere Some minor ?eaCae may occur at casin =enetrations 2ere t2erma? rot2 must @e accomoate #2e atertu@e ?o =ressure casin HRSG is not use in services 2ere ?eaCs oA t2e eD2aust or A?ue as ou? not @e =ermissi@?e
53 System "onsieration #2e atertu@e ?o =ressure casin HRSG may enerate steam at a sin?e =ressure ?eve? or mu?ti=?e =ressure ?eve?s Generatin at mu?ti=?e =ressure ?eve?s may increase t2e eAAectiveness oA recoverin t2e 2eat Arom t2e as an i?? =rovie steam Aor various =?ant nees "om@ustion tur@ine HRSGs use in coeneration or com@ine cyc?e =oer =?ants oAten enerate steam at to or t2ree =ressure ?eve?s Eac2 =ressure ?eve? may 2ave its on economier, eva=orator, or su=er2eater section !u?ti=?e =ressure ?eve? com@ustion tur@ine HRSGs oAten =rouce 2i2 =ressure steam Aor steam tur@ines, intermeiate =ressure steam Aor inMection into com@ustion tur@ines Aor &% contro? or inuction into steam tur@ines, an ?o =ressure steam Aor eaerators D
-2en steam reuirements are reater t2an can @e o@taine it2 t2e 2eat avai?a@?e Arom a com@ustion tur@ine eD2aust as, su==?ementary Airin can @e use to increase t2e avai?a@?e 2eat $A steam is reuire 2en t2e com@ustion tur@ine as A?o is curtai?e, Ares2'air Airin see 5/11: it2 am@ient com@ustion air can @e use to enerate steam ( as @y=ass system can @e =rovie to iso?ate t2e as source Arom t2e HRSG #2is i?? a??o ine=enent o=eration oA t2e as source or HRSG ( com@ustion tur@ine can @e starte it2 t2e as @y=asse to t2e atmos=2ere Aor ra=i startu= !ou?atin t2e as can a?so reuce t2e t2erma? s2ocC oA start'u= to t2e HRSG or contro? t2e HRSG steam out=ut #2e as may @e s?i2t?y a@ove or @e?o atmos=2eric =ressure "om@ustion tur@ine eD2aust static =ressures are ty=ica??y in t2e rane oA ; inc2es to 1/ inc2es H % an t2e HRSG casin esin =ressure is ty=ica??y ) inc2es H % Fire 2eater A?ue as =ressures are norma??y s?i2t?y @e?o atmos=2eric =ressure F?ui cata?ytic cracCin reenerator A?ue as =ressure may @e 1 =oun =er suare inc2 aue or reater #2e HRSG casin is norma??y ?imite to as =ressures oA 5 =ouns =er suare inc2 aue or ?ess ue to t2e =ractica? strent2 oA t2e as =at2 enc?osure casin For com@ustion tur@ine HRSGs, t2e as =ressure ro= s2ou? @e o=timie consierin t2e reuction in com@ustion tur@ine out=ut it2 increase @acC =ressure an t2e en2ance 2eat recovery it2 increase as =ressure ro= in t2e HRSG "om@ustion tur@ine eD2aust as tem=erature may rane Arom K5F to 11F -2en su==?ementary Aire, t2e as tem=erature enterin t2e HRSG may @e as 2i2 as 1;F it2out ater a?? construction #2e as tem=erature eDitin t2e HRSG is norma??y in t2e rane oA )5F to 5F #2e eDit as tem=erature e=ens on Aeeater tem=eratures, steam reuirements, an corrosion consierations #2e eDit as tem=erature s2ou? @e a@ove t2e ater an aci e =oint oA t2e as to avoi eDcessive corrosion oA t2e casin #o =revent corrosion, t2e tem=erature oA tu@e an Ain surAaces eD=ose to t2e as s2ou? @e maintaine a@ove t2e ater an aci e =oints un?ess s=ecia? meta??ury is use Feeater =re2eat sections are sometimes @y=asse runry: 2en Airin oi? to =revent corrosion oA t2e section Feeater =re2eat coi?s may contain ater t2at 2as not @een eaerate #u@e meta??ury ot2er t2an car@on stee? may @e reuire For environmenta? consieration, HRSGs are oAten reuire to contain emission contro? eui=ment suc2 as se?ective cata?ytic reuction systems Aor &% contro? Emission contro? systems are ?ocate it2in t2e HRSG suc2 t2at t2e A?ue as tem=erature rane in t2e system is correct Aor a se?ective ca ta?ytic reuction system o=eratin tem=erature rane #2e ?ocation an o=eratin tem=erature rane is inA?uence @y as tur@inesu==?ementary Airin moes oA o=eration -2en Aou?in is antici=ate, c?eanin =rovisions may @ e reuire #2e conAiuration oA t2e 2eat transAer surAace may 2ave to @e moiAie to en2ance c?eanin Protection Arom Areein is es=ecia??y im=ortant Aor HRSGs use in cyc?ic service Provisions Aor ra=i start'u= may a?so @e inc?ue suc2 as steam s=arin or steam coi? 2eatin in rums to maintain t2e =ressure com=onents in a arm conition )
)
D
54 (vantaes #2e HRSG can recover enery ot2erise eD2auste to t2e atmos=2ere rat2er t2an @urnin Aue? in a Aire @oi?er, reucin =?ant Aue? consum=tion an emissions #2e ?o =ressure stee? casin esin =ermits very ?are units t2at can 2an?e 2i2 vo?umes oA 2ot ases an =rouce ?are uantities oA steam #2e HRSG is ca=a@?e oA ra=i start'u= #2e conAiuration may @e varie to suit =?ant eui=ment an =?ot reuirements .iAAerent =rocess steam users can @e su==?ie Arom one =iece oA eui=ment Emission contro? eui=ment can @e incor=orate in t2e ?o =ressure casin HRSG at o=timum o=eratin tem=eratures %t2er HRSG ty=es may not 2 ave t2is ca=a@i?ity
55 .isavantaes #2e atertu@e ?o =ressure casin HRSG is not suita@?e Aor sma?? as vo?umes #2e HRSG casin is ?imite to esins reuirin 5 =ouns =er suare inc2 aue or ?oer HRSGs not enc?ose in @ui?ins must @e interie 2 en insta??e in co? c?imate ?ocations
5/ !ec2anica? .escri=tion 5/1 H%R$I%&#(L #UBE E*(P%R(#%R #2e A?o it2in a 2orionta? tu@e eva=orator norma??y is Aorce circu?ation as escri@e in (==eniD B, an Fiures 1/ an 1K #2e steam rum is mounte remote?y Arom t2e tu@es $t is =ossi@?e to esta@?is2 natura? circu?ation t2rou2 2orionta? tu@es @y e?evatin t2e ater out?et Arom t2e steam rum suAAicient?y a@ove t2e tu@es Hoever, 2yrau?ic resistance an va=or @?anCetin in t2e tu@es are =otentia? =ro@?ems Force circu?ation A?o is enera??y =reAerre Aor 2orionta? tu@es
5/) *ER#$"(L #UBE E*(P%R(#%R #2e A?o it2in a vertica? tu@e eva=orator norma??y is natura? circu?ation as escri@e in (==eniD B an Fiures 1; an 19 .oncomers can @e eDterna? to t2e as stream connectin t2e u==er rum an ?oer rum .oncomers can a?so @e ?ocate it2in t2e as stream "ircu?ation rates must consier 2eat in=ut to an interna? oncomer
5/3 $&"L$&E. #UBE E*(P%R( E*(P%R(#%R #%R #2e A?o it2in inc?ine tu@e eva=orator arranements is Arom a ?oer rum or 2eaer u=ar t2rou2 =ara??e? inc?ine tu@es to a co??ector rum, 2eaer, or t2e steam rum &atura? circu?ation is uti?ie, simi?ar simi?ar to t2at escri@e Aor vertica? tu@es #2e s?o=e oA t2e tu@es an t2e conAiuration oA t2e rums, 2eaers, tu@es, an eD2aust as as =at2 is critica? to =ro=er o=eration oA an inc?ine tu@e arranement
5/4 PREHE(#ERS, E"%&%!$IERS, (&. SUPERHE(#ERS $n aition to t2e eva=orator, t2e HRSG may inc?ue an economier section to 2eat t2e Aeeater anor a su=er2eater section Aor su=er2eatin steam See Fiures 1/, 1/, 1K 1K,, an 19: 19 : !u?ti=?e =ressure ?eve? HRSGs may 2ave economiers or su=er2eaters Aor more t2an one =ressure ?eve? ( steam re2eater, re2eater, Aeeater =re2eater, or a eaeratorsteam eneratin coi? may @e inc?ue at a==ro=riate eD2aust as tem=erature ?ocations #2e eD2aust as norma??y =asses over t2e su=er2eater, steam enerator, enerator, an economier in t2at orer: to o=timie t2e 2eat transAer eAAectiveness oA t2e HRSG (?ternative arranements may @e use, suc2 as interatin economiers, eva=orators, an su=er2eaters oA iAAerent =ressure ?eve?s to o=timie 2eat transAer rat2er t2an ?ocatin t2e sections oA eac2 =ressure ?eve? toet2er Su=er2eater sections may @e ?ocate it2in steam enerator sections to ?imit su=er2eater tu@e meta? tem=eratures or t2e variation oA su=er2eate steam tem=erature it2 variations in as A?o or tem=erature,
5/5 S#RU"#URE (&. "(S$&G #2e as =at2 enc?osure is norma??y a rectanu?ar @oD enc?ose on Aour sies it2 stee?
casin =?ate an o=en on @ot2 ens Aor entry an eDit oA t2e as stream Fiures 19 an 19 an ) are ) are eDam=?es oA as tur@ine eD2aust an Aire 2eater HRSG ?ayouts, res=ective?y #ransition ucts are norma??y =rovie at t2e in?et an eDit oA t2e HRSG Aor connection to t2e as source an to a uct or stacC eD2austin to t2e atmos=2ere or as c?eanin system (n eDterna? structura? ArameorC intera? to t2e casin =?ate enc?osure su==orts t2e tu@es, 2eaers, an steam rums *ertica? *ertica? tu@es an t2eir rums or 2eaers may @e su==orte eit2er Arom t2e to= or @ottom oA t2e structure Horionta? tu@es may @e su==orte @y intermeiate an en tu@e su==orts #2e as =at2 enc?osure casin =?ate may @e an interna? casin or an eDterna? casin e=enin on 2et2er t2erma? insu?ation is insta??e on t2e outsie or insie oA t2e casin =?ate EDterna? =ressure casin esins are suita@?e Aor as tem=eratures to 1;F #2e car@on stee? casin is =rotecte Arom 2ot as tem=eratures @y t2e interna? insu?ation EDterna? casin esins are suita@?e Aor ra=i start'u=, it2 start'u= rates e=enent on t2e ty=e oA interna? insu?ation system use Less common, interna? casin esins oA car@on stee? may @e suita@?e Aor as tem=erature oA a==roDimate?y K5F or ?oer #2erma? eD=ansion stresses, t2erma? rot2, an acce?erate corrosion oA t2e casin =?ate are consierations Aor interna? casin esins "ar@on stee? casin =?ate it2 increase co==er content suc2 as (S#! ( )4) or )4) or ( 5;; may 5;; may @e use to im=rove corrosion resistance Ra=i start'u= it2 interna? casin esins must consier eD=ansion ca=a@i?ities ue to t2e t2erma? stresses eve?o=e @eteen t2e casin an structura? su==orts or insu?ation
5// $&SUL(#$%& $nsu?ation is =rovie on t2e casin to minimie 2ea t ?oss an =rovie =ersonne? =rotection $A t2e as tem=erature is a@ove K5F, K5F, an interna? insu?ation system is norma??y use to =rotect t2e stee? casin =?ate EDterna? insu?ation is norma??y @?ocC or @?anCet insu?ation it2 meta? ?ain Aor eat2er =rotection
$nterna? insu?ation may @e casta@?e reAractory, ceramic Ai@er, minera? oo? @?ocC, or @?anCet insu?ation $nterna? casta@?e reAractory is norma??y use Aor Aire 2eater or A?ui cata?ytic cracCin reenerator HRSGs $t is suita@?e Aor 2i2 as ve?ocities an resists erosion Arom tu@e c?eanin evices *arious ty=es oA casta@?e reAractories are avai?a@?e Aor resistance to as erosion an c2emica? attacC "asta@?e reAractories are suita@?e Aor HRSGs, =articu?ar?y 2en t2e Airin uct tem=erature eDcees 1/F $nterna? @?ocC or @?anCet insu?ation is norma??y use Aor co m@ustion tur@ine HRSGs #2e insu?ation is norma??y a ?ayere construction it2 t2e stee? casin o n t2e outsie an a system oA stee? ?iner =?ates on t2e insie to =revent insu?ation amae Arom as A?o ve?ocities or tu@e c?eanin evices #2e interna? stee? ?iner is constructe it2 =ane?s over?a==in in t2e irection oA eD2aust A?o 2e? in =?ace @y su==ort =ins an as2ers on t2e insie surAace oA t2e ?iner #2e =ane?s accommoate t2erma? eD=ansion @ecause t2e ees are Aree to s?ie over eac2 ot2er Liner materia?s s2ou? @e se?ecte Aor as tem=eratures an corrosion c2aracteristics
5/K #UBES Horionta? tu@e steam enerators norma??y consist oA mu?ti=?e ros oA tu@es ranin in sie Arom 1 inc2 to 45 inc2es outsie iameter #2e tu@es may @e 2eaere into =ara??e? =asses #u@es it2in t2e same =ass are connecte in series @y return @ens &atura? circu?ation vertica? tu@e steam enerators norma??y consist oA a rou= oA =ara??e? sin?e tu@e circuits Eac2 tu@e is connecte to t2e u==er rum or 2eaer an a ?oer rum or 2eaer -ater enters eac2 tu@e at t2e @ottom an A?os uno@structe vertica??y to t2e to= rum or 2eaer #u@es are norma??y ) inc2es at t2e outsie iameter Force circu?ation vertica? tu@e steam enerators are common?y use Aor A?ui cata?ytic cracCin reenerator HRSGs !u?ti=?e tu@e =asses are use @ eteen t2e in?et an out?et 2eaers #u@es are connecte it2 return @ens #2e norma? s=acin @eteen centers oA aMacent tu@es is to times t2e nomina? tu@e iameter #2e tu@es in aMacent ros in t2e as =at2 may @e arrane in an in'?ine or staere =attern For t2e same as A?o, staere arranements im=rove 2eat transAer over in'?ine arranements, @ut as =ressure ro= is increase
Gas sie eDtene surAace is use to increase t2e 2eat transAer to t2e tu@es -e?e s=ira? oun so?i or serrate Ains are norma??y use Stus may @e use 2en eDtreme Aou?in is eD=ecte #2e meta??ury oA eDtene surAace is se?ecte Aor resistance to 2i2 tem=erature oDiation Recommene maDimum tem=erature Aor various materia?s are s2on in #a@?e 1 ( minimum tem=erature ?imit resu?ts Arom corrosion reuirements 6ee= t2e co? en meta? tem=erature a@ove t2e eD2aust as e=oint to =revent aci attacC oA t2e meta? !eta? tem=eratures reuire to avoi conensation an t2e resu?tin corrosion are s2on in Fiure )1
5/; PR%*$S$%&S F%R "LE(&$&G .e=enin on t2e as com=osition or ty=e oA Aue? Aire, =articu?ate matter may @e e=osite on t2e outsie surAace oA t2e tu@es Bare tu@es are =reAera@?e iA t2e Aou?ant is a2erent Stu or Ain conAiuration can @e uti?ie an varie to minimie e=osits an accommoate c?eanin #a@?e ) =rovies recommene Ain conAiuration Aor various Aue?s an ases $A eDterna? tu@e Aou?in is antici=ate, c?eanin =rovisions s2ou? @e inc?ue (ccess oors in t2e casin sie a??s are reuire to =ermit c?eanin mec2anica??y or it2 ater as2 urin maintenance s2uton $A 2eavy Aou?in is antici=ate, t2e c?eanin ?anes s2ou? @e eui==e it2 automatic or manua??y o=erate soot@?oers as escri@e in (==eniD "
5/9 .(!PERS ( am=er can @e use Aor as @y=assin at t2e HRSG in?et #i2t as sea?in is im=ortant Gui??otine am=ers can @e =rovie Aor iso?atin t2e HRSG Arom t2e as source or Aor iso?atin iniviua? HRSGs connecte to a common eD2aust stacC ( ou@?e ui??otine it2 as'sea? =ure air can @e =rovie to =ermit o=eration oA t2e as source or =ara??e? HRSGs connecte to a common stacC 2i?e t2e HRSG is s2ut on Aor maintenance ( am=er can @e insta??e in t2e as out?et 2en t2e HRSG o=erates in cyc?ic service an
is to @e maintaine in a arm stan@y conition 2en t2e as tur@ine is not o=eratin #2e am=er may @e insu?ate
5/1 SUPPLE!E&#(L F$R$&G Su==?ementa? Airin systems use t2e oDyen containe in t2e as stream Aor com@ustion oA t2e Aue? ( su==?ementa? Airin system is =rovie 2en as tur@ine eD2aust A?o or tem=erature are insuAAicient to enerate t2e reuire su=er2eat tem=erature or, steam A?o rate $ncrease as tem=erature increases t2e tem=erature a==roac2, t2at is, saturate steam tem=erature versus A?ue as or economier out?et tem=erature Lo mean tem=erature iAAerence L!#.: tem=eratures Aor t2e HRSG 2eat transAer surAace a?so increase !u?ti=?e =ressure ?eve? HRSGs @eneAit simi?ar?y, es=ecia??y t2e 2i2er =ressure sections F?ue as 2eat avai?a@?e is reuce Aor t2e ?oer =ressure steam #2e eAAect is more =ronounce it2 sin?e'=ressure ?eve? HRSGs t2an it2 mu?ti=ressure ?eve? HRSGs Su==?ementary Airin @urners are norma??y ri uct @urners Aor Aue? as an sie'a?? @urners Aor Aue? oi? "om@ination as an oi? Airin can @e accom=?is2e @y usin @ot2 ty=es oA @urners Gri @urners are mu?ti=?e Aue? 2eaers insta??e in a =?ane norma? to t2e as A?o Burners are eua??y s=ace Arom eac2 ot2er an eDten across t2e transition uct it2 Fue? oriAices or no?es are insta??e over t2e ?ent2 oA eac2 Aue? @urner 2eaer an A?ame sta@i?iation is =rovie it2 iAAuser =?ates u=stream oA t2e @urner no?e F?ame manaement systems inc?uin =i?ots an A?ame scanners are =rovie Aor eac2 @urner =i=e -a?? @urners t2at are mounte in t2e uct siea?? Aire transverse to t2e main as A?o #2ese @urners are staere an usua??y uno==ose on t2e o==osite a??, t2ere@y a??oin Aor ?on narro A?ames F?ame sta@i?iin iAAuser =?ates are insta??e u=stream oA t2e A?ames #2e @urner an com@ustion manaement system is simi?ar to t2at oA t2e ri @urners #2is @urner may reuire a Aan to su== ?y its =rimary air %i? Airin is more easi?y 2an?e it2 t2e a?? @urners t2an it2 ri @urners
5/11 FRESH'($R F$R$&G Fres2'air Airin uses am@ient air Aor com@ustion oA t2e Aue? Force raAt systems are usua??y reuire to =rovie t2e air at suAAicient =ressure to overcome t2e as =ressure ro= oA t2e HRSG For com@ustion tur@ine HRSGs, Ares2'air Airin is use to =rouce steam 2en t2e com@ustion tur@ine is out oA service (s a siniAicant vo?ume oA Ares2 air ou? @e reuire to =rouce t2e same amount oA steam =rouce it2 t2e com@ustion tur@ine eD2aust, t2e Ares2'air Airin system is oAten esine to enerate on?y 5 =ercent oA t2e HRSG rate steam ca=acity Fres2'air Airin in com@ustion tur@ine HRSGs reuires 2i2 tem=erature am=ers in t2e eD2aust as stream an at t2e auDi?iary @urners ( am=er an sea? air Aan is use to =revent eD2aust as ?eaCs t2rou2 t2e Aan system, or t2e main com@ustion air Aan must o=erate
Fres2'air Airin in com@ustion tur@ine HRSGs reuires s=ecia? attention in se?ection oA t2e am=er an Aans Pi?ots, A?ame scanners, an a @urner manaement system are reuire Emerency automatic sitc2'over to Ares2'air Airin may @e inc?ue Fres2'air Airin can a?so @e use in Aire 2eater HRSGs Since t2e A?ue as is norma??y at ?ess t2an atmos=2eric =ressure, t2e A?ue as oes not ?eaC to t2e atmos=2ere S2utoAA am=ers are =rovie to =revent am@ient air ?eaCs into t2e HRSG Force raAt @urner systems are oAten use to =rovie automatic contro? oA t2e @urner an ti2t A?ame =atterns
5/1) E0P(&S$%& J%$&#S Bot2 corruate meta? @e??os an Aa@ric sea? eD= ansion Moints are use to accommoate uct an casin eD=ansion Bot2 esins re?y on interna? =acCe insu?ation to reuce t2e tem=erature oA t2e eD=ansion Moint sea? an eDterna? surAace #2e Aa@ric sea? eD=ansion Moint is =reAerre iA siniAicant ?atera? as e?? as aDia? eD=ansions are antici=ate ED=ansion Moints Aor HRSGs it2 interna? ?iners s2ou? @e esine it2out 2eavy meta? com=onents eDtenin Arom t2e interna? ?iner to t2e outsie casin to avoi ?oca? over2eatin oA t2e eDterna? casin =?ate
5/13 G(S *EL%"$#+ (&. FL%Gas ve?ocity in t2e HRSG is ?imite @y as sie =ressure ro= an erosion oA t2e casin insu?ation or 2eat transAer surAace (t ve?ocities @e?o ) Aeet =er secon, so?is carry' over, iA =resent, i?? e=osit on t2e 2eat transAer surAace Hi2er as ve?ocities i?? create a se?A c?eanin eAAect !aDimum as ve?ocities @eteen tu@es Aor minimiin erosion eAAects are s2on in #a@?e 3
5/14 #UBE *$BR(#$%& (&. ("%US#$" RES%&(&"E "om@ustion tur@ine an A?ui cata?y?tic cracCin reenerator HRSGs, =a rticu?ar?y ?are units it2 ?on tu@es, may @e su@Mect to A?o'inuce tu@e vi@rations an resonant acoustic vi@ration #u@e vi@ration is contro??e @y intermeiate tu@e su==orts usin meta? @ars or ?acin ires Resonant acoustic noise is reuce @y insta??in meta? @aAA?es =ara??e? to t2e as A?o to c2ane t2e resonant Areuency oA t2e as =at2
5/15 FL%- .$S#R$BU#$%& (&. S#R($GH#E&$&G .E*$"ES #2e eD2aust A?o eDitin com@ustion tur@ines is very tur@u?ent an nonuniAorm in istri@ution Some areas oA com@ustion tur@ine HRSG in?et ucts may 2ave reverse as A?o UniAorm as A?o is =articu?ar?y im=ortant Aor satisAactory su==?ementary Airin an su=er2eater =erAormance PerAorate =?ates, A?o reirection @aAA?es, or ot2er means are use to im=rove t2e A?o istri@ution HRSG in?et ucts may 2ave =erAorate =?ates insta??e u=stream oA t2e @urners an A?o reirection @aAA?es insta??e onstream oA t2e @urners F?o
reirection is oAten necessary Aor transition ucts iverin more t2an 3 erees tota? inc?ue an?e F?o moe? tests on com@ustion tur@ine HRSGs 2e?= =reict t2e as A?o istri@ution an eAAectiveness oA A?o strai2tenin evices $t is im=ortant t2at t2e test moe? correct?y simu?ates t2e com@ustion tur@ine eD2aust c2aracteristics as e?? as t2e HRSG conAiuration
5/1/ #E!PER(#URE .$S#R$BU#$%& (Ater t2e as tur@ine iAAuser, tem=erature isot2erms oA eD2aust as across t2e uct may @e nonuniAorm Aor certain as tur@ines !u?ti=?e t2ermocou=?es are recommene 2en eterminin averae cross'sectiona? uct tem=erature Hi2 ve?ocity t2ermocou=?es H*#: are necessary Aor accurate tem=erature reains at eD2aust as tem=eratures a@ove 1F %t2er t2emocou=?e ty=es, suc2 as s2ie?e, can =rovie re?ative reains @ut are not as accurate as t2e H*#
5K %=erations .escri=tion SuccessAu? HRSG o=eration e=ens on usin o=eratin =roceures 2ic2 aress HRSG esin, moes oA o=eration, an ram=u= rates
5K1 Protection evices s2ou? @e =rovie an =roceures Ao??oe as escri@e in (==eniD ( Aor t2e ater an steam =ressure =arts
5K) Protection s2ou? @e =rovie to =revent incienta??y over'=ressuriin t2e as =at2 enc?osure casin "ontro? ?oic oA HRSG an com@ustion tur@ines s2ou? @e inter?ocCe to =revent start'u= unti? eD2aust am=ers are =roven o=en an s2ou? s2ut on iA a am=er c?oses
5K3 Start'u=s can im=ose siniAicant t2erma? s2ocC to com=onents ue to t2e ra=i introuction oA 2ot as Limitations may @e a==ro=riate on t2e rate oA introuction oA t2e
2ot as, rate oA tem=erature increase in t2e =ressure =arts, or conitions at 2ic2 t2e HRSG is to @e maintaine =rior to start'u= Hot restarts aAter suen Aeeater ?oss ue to =um= tri= are even more severe an reuire s=ecia? o=eratin consierations
5K4 Protective systems s2ou? @e inc?ue to s2ut on su==?ementary or auDi?iary @urners or t2e 2ot as source 2en a==ro=riate
5K5 Fo??o start'u= an s2ut on =roceures suc2 as rainin oA su=er2eaters =rior to start' u= to =revent amae to com=onents "om@ustion tur@ine HRSGs may @e use in ai?y cyc?ica? service an may @e automatica??y contro??e Arom a =?ant istri@ute contro? system %=eratin =rovisions must Ao??o t2e =ro=er =roceures eit2er automatica??y or manua??y
SE"#$%& / ' HE(# P$PE HRSGs /1 Genera? #2e 2eat =i=e steam HRSG is @asica??y a com=act 2eat eDc2aner $n its sim=?est Aorm it consists oA a =ressure vesse? steam rum: an a @un?e oA 2eat =i=es #2e 2eat =i=es eDtract 2eat Arom a 2ot as stream an trans=ort it to t2e insie oA t2e vesse?, 2ere steam is enerate an se=arate Arom t2e ater (s 2ot as A?os over t2e va=orier section, t2e orCin A?ui insie t2e =i=e va=ories #2e va= or rises insie t2e 2eat =i=e to t2e conenser section $n t2e conenser section, t2e orCin A?ui re?eases its ?atent 2eat causin t2e orCin A?ui va=or to conense #2rou2 ravity assistance, t2e conense orCin A?ui A?os @acC on to t2e va=orier section #2e cyc?e is t2en re=eate $n t2is =rocess, 2eat is conucte Arom t2e 2ot ases t2rou2 t2e 2eat =i=e to @oi? ater in t2e steam rum #2is va=oriationconensation cyc?e an t2e resu?tin 2eat trans=ort continues as ?on as t2e tem=erature oA t2e as =assin over t2e 2eat =i=e is reater t2an t2e tem=erature oA t2e ater 2ic2 surrouns t2e @are section oA t2e =i=e Eac2 2eat =i=e =asses t2rou2 t2e =ressure vesse? a?? #2ere is @asica??y on?y one ty=e oA 2eat =i=e HRSG 2oever, t2e 2eat =i=es an t2e =ressure vesse? can @e varie $n a 2eat =i=e HRSG, t2e 2ot as A?os over t2e eDterior oA t2e 2eat =i=e @un?e as s2on in Fiure ))
/) (==?ication /)1 (s a re?ative?y ne eve?o=ment, 2eat =i=e HRSGs 2ave @een use ?ess in inustry t2an ot2er ty=es oA HRSGs Heat =i=e HRSGs can @e esine to recover enery Arom t2e 2ot ases oA various insta??ations suc2 as
a Fire 2eaters @ "a?ciners c 6i?ns $ncinerators e Gas tur@ines F?ue ases Arom @urnin natura? an reAinery as, oi?, an coa? Aue?s are acce=ta@?e
/)) Heat =i=e HRSGs ty=ica??y enerate ?o =ressure 15 =ouns =er suare inc2 aue to )5 =ouns =er suare inc2 aue: steam #2e unit can @e esine Aor muc2 2i2er =ressures iA t2e a==?ication MustiAies it $n?et A?ue as tem=eratures to ;F can @e acce=te @y =ro=er overa?? esin an careAu? se?ection oA t2e orCin A?ui
/3 System "onsieration /31 .ES$G& "%&S$.ER(#$%&S !aMor esin consierations oA 2eat =i=e HRSGs inc?ue a "ircu?ation @ Pressure ro= c Steam ua?ity "?eanin e Heat =i=e siin A Se?ection oA t2erma? trans=ort A?ui
/3) "$R"UL(#$%& #2e 2eat =i=e HRSGs can @e esine to 2ave 2i2 steam rum circu?ation ratios usin natura? circu?ation #2e 2ea s=ace on eac2 en oA t2e rum can =rovie natura? circu?ation Aor t2e ater A?o 2i?e t2e iAAerence in t2e A?ui ensity @eteen t2e ater in t2e 2eas an t2e atersteam miDture in t2e tu@e @un?e =rovie t2e necessary circu?ation rivin Aorce #2e tu@es are enera??y Ainne on t2e as sie, an tu@e'to'tu@e s=acin s2ou? @e ictate @y Ain ti= c?earance reuirements #2is enera??y resu?ts in a
?are tu@e'to'tu@e c?earance on t2e ater sie it2 t2e associate ?o =ressure ro= Hi2 circu?ation rates an ie tu@e s=acin =en'nit t2e 2eat =i=e unit to o=erate saAe?y at 2eat A?uDes oA u= to 5, Btu2ours =er suare Aoot in t2e @are tu@e area oA t2e conenser section: See )3)) Aor aitiona? inAormation
/33 S#E(! 7U(L$#+ #2e steam rum must @e ?are enou2 to =rovie s=ace Aor t2e steam to se=arate Arom t2e ater $nterna? steam se=arators s2ou? @e inc?ue to reuce ater carryover in t2e steam $A aeuate se=aration s=ace is not avai?a@?e, a se=arate steam rum or an eDterna? in'?ine se=arator may @e use #2e steam =rouce is at saturation conitions at t2e out?et oA t2e steam rum See (==eniD (
/34 PRESSURE .R%P #2e as ve?ocity may @e ?imite @y t2e avai?a@?e =ressure ro= (n increase in t2erma? =erAormance can @e o@taine @y ain ros, increasin t2e eDtene surAace, or ecreasin t2e tu@e =itc2 (??, 2oever, resu?t in an increase in as sie =ressure ro= For a iven =itc2, increasin t2e as sie ?ent2 oA t2e tu@es or ain more tu@es =er ro i?? increase t2erma? =erAormance 2i?e ecreasin =ressure ro=
/35 HE(# P$PE S$I$&G Se?ection oA t2e 2eat =i=e iameter, ?ent2, an 2otco? ?ent2 ratios are a?? intere=enent ED=erience 2as s2on t2at iameters in t2e rane oA 15 inc2es to ) inc2es =rovie o=timum 2eat transAer ca=acity #2e 2otco? ?ent2 ratio is etermine @y t2e ca=acity avai?a@?e in t2e 2eat =i=e an t2e eDtene surAace a==?ie to t2e as sie Genera??y, t2e most economica? 2eat eDc2aner is one 2ic2 2as t2e ?onest 2eat =i=es,
?imite to reasona@?e as=ect ratios Aor connectin uctorC
/3/ #HER!(L #R(&SP%R# FLU$. SELE"#$%& Se?ection oA =ro=er t2erma? trans=ort A?uis is @ase on t2e o=eratin tem=erature rane an t2e A?uD reuire #y=ica? A?uis inc?ue ater, to?uene, an na=2t2a?ene %=eratin tem=erature ranes Aor t2ese an ot2er A?uis are inicate @y Fiure )3 By se?ectin iAAerent A?uis Aor iAAerent ros, t2e a==ro=riate Ai?m tem=erature oA t2e trans=ort A?ui can @e ac2ieve .eraation ?imits oA t2e various trans=ort A?uis s2ou? @e iscusse it2 t2e manuAacturer #y=ica??y, 2eat =i=e t2erma? trans=ort ?imits i?? overn esin
/3K FREEIE PR%#E"#$%& S+S#E! .urin =erios oA s2ut on 2en Areein conitions eDist, a =rotection system must @e em=?oye to maintain ater @ase trans=ort A?ui tem=eratures a@ove 3)F "onventiona? =recautions Aor steam systems a==?y to t2e steam enerator sie oA t2e unit
/4 (vantaes /41 Eac2 2eat =i=e is an ine=enent o=eratin 2eat eDc2aner $A one 2eat =i=e Aai?s, s2ut on is not reuire ue to t2e sma?? im=act on t2e overa?? unit =erAormance
/4) #2e 2eat =i=es are AiDe on?y at t2e center connection =oint to t2e =ressure vesse? #2us, t2ey are a??oe to Aree?y eD=an an contract t2erma??y a@out t2e attac2ment =oint
/43 #2e @ounary @eteen t2e steam an as is com=ose oA t2e to tu@e a??s oA t2e 2eat =i=e rat2er t2an one tu@e a?? in most ot2er esins For steam to =ass to t2e as, a 2eat =i=e ou? 2ave to 2ave to 2o?es, one on t2e steam sie an one on t2e as sie, a very un?iCe?y situation
/5 .isavantaes /51 .ue to trans=ort A?ui ?imitations, as stream steay state tem=eratures in eDcess oA ;F are not current?y =ractica? in t2e 2eat =i=es
/5) $nustria? eD=erience is ?imite
// !ec2anica? .escri=tion //1 S#E(! .RU!S Steam rums use Aor 2eat =i=e HRSGs are essentia??y conventiona? cy?inrica? =ressure vesse?s eDce=t t2at a means must @e =rovie Aor =ressure @ounary =enetration @y t2e 2eat =i=es %ne met2o oA accom=?is2in t2is is @y t2e aition oA a ?are, A?at =ressure =?ate, containin mu?ti=?e o=enins, in t2e sie oA t2e vesse? #2e steam rum an 2eat =i=es are mec2anica??y AiDe to one anot2er an cannot @e se=arate #2e steam rum is =enetrate @y t2e 2eat =i=es at a / eree to 9 eree an?e Arom t2e 2orionta? #2e units can @e esine Aor A?ue as A?o in eit2er irection
//) HE(# P$PES #2e 2eat =i=e consists oA a tu@e it2 Ains on t2e 2ot as en, a t2erma? s?eeve 2ic2 iso?ates t2e 2i2 2eat A?uD oA t2e 2eat =i=e Arom t2e Moint at t2e =i=evesse? interAace to reuce t2e =ossi@i?ity oA crevice corrosion:, an a t2erma? trans=ort A?ui #2e tu@e is manuAacture @y ca==in @ot2 ens, evacuatin, =artia??y Ai??in it2 t2erma? trans=ort A?ui, an t2en =ermanent?y sea?in See Fiure )4
//3 #UBE SUPP%R#
#o =revent t2erma??y inuce stresses, t2e 2eat =i=e uti?ies a sin?e AiDe =oint ?ocate 2ere t2e 2eat =i=e =enetrates t2e vesse? ( su==ort =?ate is oAten ?ocate at t2e ?oer en oA t2e 2eat =i=e Raia? c?earance @eteen t2e tu@es an t2e su==ort =?ates is suc2 t2at t2e tu@es are Aree to move in t2e aDia? irection @ut are su==orte ?atera??y #2is Aree s?iin ?atera? su==ort a?so 2e?=s to ?imit tu@e vi@ration
//4 $&#ER&(LS !aMor interna? concerns are t2e ty=e oA A?ui to @e use, t2e conensin surAace, t2e ?iui istri@ution, an t2e se=aration oA t2e ?iui an va=or A?os
( mec2anism is reuire to et t2e eva=orator en oA t2e 2 eat =i=e Usua??y a ca=i??ary icCin structure is a==?ie to t2e inner a?? oA t2e 2eat =i=es #2e icCin Aunction is enera??y accom=?is2e @y roovin t2e inner a?? or @y a mes2 screen insta??e on t2e insie oA t2e =i=e #2e icC ras t2e ?iui 2eat transAer A?ui u= aroun t2e inner a?? oA t2e tu@e, =roviin a com=?ete?y ette surAace Aor eva=oration (?t2ou2 a ca=i??ary structure is a?so common?y em=?oye in t2e conenser en oA t2e 2eat =i=e, it serves a iAAerent =ur=ose $n t2is a==?ication t2e structure =rovies a rou2ene surAace 2ic2 Aunctions to en2ance t2e interna? 2eat transAer Heat =i=e interna?s reuire a return =at2 Aor t2e ?iui A?o Arom conenser to eva=orator $A t2e 2eat =i=e is 2orionta?, t2e eva=orator i?? @e starve at any reasona@?e 2eat A?uD eman @ecause t2ere i?? @e insuAAicient 2ea to =rovie ?iui A?o %n t2e ot2er 2an, iA t2e =i=e is vertica?, A?o =ro@?ems can occur @ecause oA t2e =erco?ator eAAect iA s=ecia? interna?s are not incor=orate #2ereAore, most 2eat =i=es are mounte at an an?e #2e an?e s2ou? resu?t in 2eat 2i2 enou2 to =rovie aeuate ?iui A?o, @ut ?o enou2 so t2at t2e ?iui 2as suAAicient A?o an ve?ocity to et t2e entire eva=orator @eAore it reac2es t2e ?oer en oA t2e 2eat =i=e
(PPE&.$0 ( ' S#E(! .RU!S
(1 Genera? ( steam rum is a =ressure vesse? 2ose =rimary =ur=ose is to se=arate ?iui an va=or =2ases Steam rums a?so =rovie an o=eratin ater storae ca=acity
(11 #2e steam rum s2ou? =rouce saturate steam a==roac2in 1 =ercent ua?ity #2ere s2ou? @e minima? ater so?is carryover to onstream eui=ment #2e steam rum s2a?? @e esine in accorance it2 t2e (S!E "oes $t is attac2e to t2e steam eneratin section oA an HRSG irect?y or inirect?y t2rou2 Aeeater 2eaers, risers, an oncomers
(1) #2e rum =rovies Aor t2e Ao??oin a Steam se=aration interna? evices @ -ater storae ca=acity c $nstrumentation connections B?oon Aaci?ities e "2emica? inMection Aaci?ities A %ver=ressure =rotection saAety va?ves:
(13 ( ty=ica? steam rum it2 2i2 =urity steam se=aration interna? evices is i??ustrate in Fiure ('1
(14 Steam =urity is t2e ratio oA t2e ei2t oA tota? so?is =er unit ei2t oA steam =rouce
() (==?ication ()1 ( steam rum is insta??e in most HRSGs 2ere t2e steam must meet s=eciAie reuirements Aor steam =urity Steam rums, 2oever, are not reuire Aor once't2rou2 Aorce circu?ation HRSGs
()) Severa? steam =ressure ?eve?s may @e enerate in t2e HRSG ( se=arate steam rum, inc?uin re?ate anci??ary Aaci?ities, must @e su==?ie Aor eac2 =ressure ?eve?
()3 #2e steam rum Aor an HRSG may @e s2are it2 ot2er 2eat recovery systems Eac2 a==?ication is custom esine e=enin on t2e 2eat recovery systemsN s=eciAic reuirements
(3 Steam Se=aration (31 -ater an so?is ?eavin t2e steam rum it2 t2e steam is ca??e carryover "arryover is eD=resse in eit2er =arts =er mi??ion ==m: or =arts =er @i??ion ==@:
(3) EDcessive carryover can ?ea to serious =ro@?ems (cce=ta@?e carryover rates e=en on t2e steam use an t2e com=osition oA t2e carryover .etrimenta? eAAects oA eDcessive carryover may inc?ue a Su=er2eater tu@e Aou?in, resu?tin in tu@e over2eatin an corrosion @ Reuction oA steam tur@ine eAAiciency an corrosion resu?tin Arom @?ae an no?e Aou?in
c "ontamination oA =rouct or cata?yst contacte @y t2e steam
(33 For steam tur@ine a==?ication or Aor onstream steam su=er2eatin it is =ruent to esta@?is2 ?imits Aor @oi?er ater an steam =urity #a@?es ('1 an (') are =u@?is2e @y iAAerent oraniations an are =resente as eDam=?es #2e Ao??oin c?ariAications a==?y to #a@?e ('1 Aor rum @oi?ers a !aDimum ) ==m tota? isso?ve so?is in t2e steam at or @e?o / =ouns =er suare inc2 aue rum =ressure, an 1 ==m tota? isso?ve so?is maDimum a@ove / =ouns =er suare inc2 aue are saAe ?imits Hi2er ?eve?s may @e acce=ta@?e @ Steam =urity s2ou? @e ac2ieve 2i?e o=eratin it2 @oi?er ater tota? isso?ve so?is at t2e 2i2 en oA t2e rane inicate in #a@?e ('1 #2e rum su==?ier s=eciAies t2e maDimum tota? isso?ve so?is ?eve? in t2e @oi?er ater at 2ic2 a s=eciAie steam =urity is uarantee
(34 !ec2anica? carryover is t2e carryover 2ic2 is isso?ve in t2e entraine ater in t2e e?ivere steam .rum interna?s esine Aor ater remova? irect?y aAAect t2e mec2anica? carryover uantity Primin is t2e isc2are oA steam 2ic2 contains eDcessive amounts oA entraine ater Primin is a conseuence oA a 2i2 rum ater ?eve? or oA Aoamin
(35 Steam ua?ity ?eavin t2e rum is e=enent on t2e eAAiciency oA t2e steamater se=aration, t2e so?is concentration in t2e rum a ter, an on t2e reuire steam =urity (cce=ta@?e steam ua?ity an =urity Aor =rocess or steam 2eatin a==?ications may @e ac2ieve @y ravity se=aration a?one Hoever, mu?ti=?e staes oA steamater se=aration are usua??y necessary to e?iver 2i2 ua?ity an 2i2 =urity steam
(3/ Hi2 =urity steam rums use severa? staes oA se=aration #2e Airst stae removes t2e @u?C oA t2e ater Arom t2e miDture its esin may reuire t2e Ao??oin a .eA?ectors @ PerAorate =?ates c "entriAua? vorteD se=arators
%t2er =ro=rietary evices #2e steamater miDture moves t2rou2 severa? irectiona? c2anes, a??oin ater ro=?ets to Aa?? out #2e Aina? staes oA se=aration can em=?oy t2e Ao??oin a -ire mes2 @ "2evron riers c "entriAua? se=arators "om@inations oA $tems a, @, an c #2e iAAicu?ty oA steam se=aration increases as rum =ressure increases @ecause t2e steam an ater =2ase ensity iAAerence ecreases
(3K Some carryover constituents suc2 as si?ica isso?ve in @ot2 t2e ?iui an va=or =2ases #2ese constituents ten to increase in concentration in t2e va=or =2ase as =ressure increases Liui =2ase contaminants can @e minimie @y eAAicient steamater se=aration Hoever, va=or =2ase contaminants can on?y @e contro??e @y steam as2in, @y remova? oA t2e contaminant t2rou2 =ro=er treatment oA t2e Aee ater, or increasin t2e @?oon rate Si?ica carryover at 2i2er =ressures over 1 =ouns =er suare inc2 aue: resu?ts more Arom va=oriation an so?u@i?ity oA si?ica in t2e steam t2an Arom entraine ater
$n steam as2in, t2e steam an si?ica va=or are contacte @y ?o so?is ater, suc2 as steam conensate #2e si?ica in t2e steam isso?ves in t2e as2 ater an reuces t2e si?ica va=or carryover
(4 -ater Storae (41 .urin transient o=eration, t2e steam rum va=or vo?ume i?? vary (s steam eman is increase, t2e system =ressure i?? ecrease #2is resu?ts in A?as2in, an an instantaneous increase oA steam eneration #2e ater ?eve? rises @ecause oA t2e aitiona? steam vo?ume in t2e ater =2ase #2is is ca??e sure or se?? #2e o==osite 2a==ens urin a reuction in steam eman ( =ro=er?y tune contro? system re' esta@?is2es norma? ater ?eve? 2en steay state o=eration is reac2e Sure vo?ume in t2e rum s2ou? @e aeuate to avoi eit2er siniAicant ater carryover =rimin: or ?o ?eve? a?arm #2is assumes o=eration initia??y at norma? ater ?eve? an ?oa sins at a rate oA =?us or minus ) =ercent oA t2e maDimum continuous ratin =er minute Lo =ressure steam systems are more sensitive to t2is =2enomenon
(4) #2e iAAerence in vo?ume @eteen t2e norma? ater ?eve? an t2e ?o'?o ?eve? is ca??e t2e storae ca=acity Storae =rovies ater to t2e HRSG iA t2e Aee ater A?o is interru=te or is momentari?y inaeuate #y=ica??y, rum storae vo?ume is a minimum oA 3 minutes oA esin Aee ater A?o Aor rum =ressures oA K5 =ouns =er suare inc2 aue an 2i2er an 5 to 1 minutes at ?oer =ressures For critica? service, steam rum ater storae vo?umes may @e 2i2er an are a Aunction oA t2e re?ia@i?ity oA @oi?er Aeeater su==?y Eac2 system s2ou? @e eva?uate on a case'@y'case @asis $n some cases, sure vo?ume may ictate rum sie
(5 !ec2anica? .escri=tion (51
#2e (S!E "oe, eit2er Section $ or Section *$$$, .ivision 1 is norma??y a==?ie Aor t2e =ressure vesse? esin oA t2e steam rum $A t2e HRSG is Aire, t2en Section $ may a==?y $A t2ere is no irect Airin, Section *$$$, .ivision 1 may @e a==?ie, e=enin on t2e ?oca? reuirements Some users s=eciAy Section $ esin it2 Section *$$$, .ivision 1 stam=in Aor an unAire HRSG #2is esta@?is2es more strinent Section $ esin reuirements 2i?e avoiin t2e more Areuent system ins=ection reuirements oA Section $ stam=e HRSGs "om=?iance it2 reu?ations oA ?oca? aut2orities is manatory
(5) #2e ?ayout an sie oA t2e rum must a??o Aor interna? ins=ection, maintenance, an re=air
(5)1 #2e interna?s s2ou? @e remova@?e an sie to =ass t2rou2 a manay ( 1) inc2 @y 1/ inc2 minimum sie manay is insta??e in eac2 rum 2ea
(5)) #2e s=acin oA interna?s s2ou? a??o maintenance =ersonne? to =ass aroun o@structions an orC a?on t2e com=?ete ?ent2 oA t2e rum BaAA?e =?ates an ot2er se=aration evices t2at cover tu@es s2ou? @e reai?y remova@?e
(5)3 #2e esin s2ou? =ermit eAAicient tu@e remova? an re=?acement #2e area oA t2e tu@e Aie? must @e c?ear oA =ermanent o@structions to a??o s=ace Aor tu@e ro??in an sea? e?in
(5)4 ( steam rum is usua??y not ?ess t2an 3/ inc2es in iameter in orer to =rovie aeuate access an vo?ume
(53 Steam rum esin =ressure s2ou? @e suAAicient?y a@ove t2e eD=ecte maDimum o=eratin =ressure to =rec?ue unnecessary isc2ares Arom t2e steam saAety va?ves #2e =ressure marin is usua??y a =ercent oA t2e va?ve set =ressure, an is e=enent u=on t2e ty=e oA va?ve -it2 marins ?ess t2an 1 =ercent, consu?t t2e va?ve manuAacturer rearin va?ve suita@i?ity
(54 Sie oA steam an ater connections must =rovie acce=ta@?e A?ui ve?ocities an =ressure ro= uner a?? o=eratin conitions #2e =ossi@i?ity oA t2erma? stresses Arom re?ative?y coo? Aee ater or c2emica? Aee enterin t2e 2ot rum must @e consiere $n t2icC a??, 2i2 =ressure esins, it may @e necessary to =rovie t2erma? s?eeves at t2e rum a?? ( t2erma? s?eeve is a =i=e s?eeve 2ic2 =enetrates t2e rum a?? t2rou2 2ic2 t2e Aee ater or c2emica? Aee =i=e is eDtene
(55 *a=or'Aree ater s2ou? enter t2e HRSG oncomers #2e esin an ?ocation oA t2e Airst stae se=arators re?ative to t2e oncomers, an t2e use oA @aAA?es an vorteD @reaCers, can eAAective?y =revent va=or Arom enterin t2e oncomer no?es
(/ .rum %=eratin Leve?s #2e Cey o=eratin ?eve?s in t2e steam rum are a &orma? ater ?eve? @ Hi2 an ?o ater ?eve? c Hi2'2i2 ater ?eve? Lo'?o ater ?eve?
(/1 &orma? ater ?eve? is t2e ater ?eve? 2ic2 t2e contro? system maintains urin steay state o=eration #2e norma? ?eve? is near t2e rum center?ine to en2ance moisture se=aration an to =rovie aeuate ater storae vo?ume #2is ater ?eve? may @e a@ove t2e rum center?ine Aor rums 2ic2 2ave mec2anica? steam se=arators
(/) Hi2 an ?o ater ?eve? are t2ose a@ove an @e?o t2e norma? ater ?eve? 2ic2 esta@?is2 t2e maDimum o=eratin rane oA o=eratin ?eve?s to @e eD=ecte urin ?oa sins #2e istance @eteen 2i2 an ?o ?eve?s an norma? ?eve? is ty=ica??y Arom =?us or minus / inc2es to =?us or minus ) inc2es (?arms are set Aor @ot2 2i2 an ?o ?eve?s
(/3 Hi2'2i2 ater ?eve? is t2e 2i2est ?eve? at 2ic2 t2e su==?ier i?? uarantee t2e steam =urity @ecause oA t2e =ossi@i?ity oA ater @ein entraine in t2e ?eavin steam
(/4 Lo'?o ater ?eve? is t2e ?oest ?eve? at 2ic2 t2e HRSG s2ou? @e o=erate Be?o t2is ?eve? t2e eva=orator tu@es may @e im=ro=er?y ette, resu?tin in tu@e or rum over2eatin Lo'?o ?eve? a?arm is a?so use to s2ut on uct @urners oA Aire HRSGs, to iso?ate unAire HRSGs Arom t2e 2ot =rocess as iA eui==e it2 a as @y=ass system, or to start un?oain t2e com@ustion tur@ine .e=enin u=on s=eciAic conitions, s2ut on may 2ave to @e initiate @eAore ?o'?o ?eve? is reac2e
(K #rim an $nstrumentation (K1 #2e steam rum accommoates =ressure saAety va?ves ater ?eve? inication an contro?, a?arm, an s2uton instrumentation $nstrumentation must satisAy a==?ica@?e coes an reu?ations
(K) SaAety va?ves: insta??e a@ove t2e va=or s=ace oA t2e rum =rovie =art or a?? oA t2e reuire re?ievin ca=acity oA t2e HRSG $A to va?ves are reuire, t2ey are eit2er ientica? or t2e sma??er va?ve is norma??y set to ?iAt Airst Re?ieA oA t2e Au?? steamin ca=acity must @e =rovie on t2e steam rum or in com@ination it2 su=er2eater saAety va?ves in accorance it2 (S!E "oe
(K3 Leve? inication is =rovie @y one or more ?eve? aues, ?eve? transmitters, or remote ?eve? inicators, connecte to t2e rum or ater co?umns .rum ?eve? can @e o@serve @y irect vision at t2e rum =?atAorm ?eve? Leve? inication may a?so @e transmitte to rae or a contro? room Reunancy oA instrumentation is esira@?e to avoi s2ut ons Aor re=air $t is 2e?=Au? on ?on rums to s2o en'to'en ?eve? variations on t2e rum, =articu?ar?y 2en riser an oncomer connections are not symmetrica? a?on t2e rum ?ent2 #2e useAu? rane oA t2e ?eve? aes s2ou? @e careAu??y se?ecte so t2at t2e tota? esire rane is o@taine #2e (S!E "oe reuirements may not =rovie t2e esire rane oA ?eve? coverae #ransmitters an ot2er remote inicators enera??y cover t2e rane Arom 2i2' 2i2 to ?o'?o ?eve? an it is esira@?e to =rovie simi?ar Au?? rane ae ?ass coverae
(K4 #o'e?ement or t2ree'e?ement systems are use Aor contro?
(K41
( to'e?ement system monitors t2e rum ater ?eve? an t2e e?ivere steam A?o ( Aee'@acC sina? is @ase on t2e steam A?o, an t2e eman Aor c2anes in t2e Aee ater is antici=ate @eAore t2e ?eve? actua??y c2anes
(K4) ( t2ree'e?ement system monitors rum ater ?eve?, isc2are steam A?o, an Aee ater A?o #2e steam A?o is com=are to t2e ater A?o an ?eve? c2ane is antici=ate t2e Aee ater A?o is aMuste @eAore t2e ?eve? c2anes siniAicant?y #2ree'e?ement contro? is usua??y more res=onsive t2an to'e?ement contro?
(K43 #2e ?eve? contro? system can @e tune, or can incor=orate com=uterie =rorams to minimie t2e transient eAAects
(; "ontro? oA -ater "2emistry (;1 Provisions are incor=orate in t2e steam rum to co ntro? t2e concentration oA so?is in t2e rum ater So?is in t2e rum ater i?? concentrate as steam is enerate $A t2e rum ater so?is concentration eDcees certain ?eve?s, Aoamin may occur 2ic2 can ?ea to entrainment oA ater an so?is in t2e steam "ertain oranics suc2 as oi? an rease in t2e rum ater can a?so cause Aoamin: #a@?e ('1 Arom (B!(: contains enera? recommenations Aor rum ater c2emistry #a@?e ('1 va?ues are eDc?usive oA si?ica (t =ressures a@ove 1 =ouns = er suare inc2 aue, si?ica concentration in va=or Aorm increases, reuirin s=ecia? contro? (na?ysis oA t2e steam is necessary to etect carryover ( sam=?e connection usin an isoCinetic =ro@e as escri@e in (S#! .1// s2ou? @e insta??e to eDtract a re=resentative steam sam=?e #2e sam=?e connection s2ou? @e insta??e on t2e steam out?et ?ine or ?ines
(;) So?is concentration in t2e rum ater is contro??e @y removin some oA t2e 2i2 so?is rum ater, 2ic2 is re=?enis2e it2 ?o so?is Aee ater #2is =rocess is ca??e @?oin on (t steay state, t2e A?o @a?ance aroun t2e steam rum is
W"ere& + O Feeater A?o rate, in =ouns =er 2our S O Steam A?o rate, in =ouns =er 2our
B O "ontinuous @?oon A?o rate, in =ouns =er 2our #2e tota? isso?ve so?is @a?ance is
C O #ota? isso?ve so?is in Aeeater, in =arts =er mi??ion t
+ O Feeater A?o rate, in =ouns =er 2our C O #ota? isso?ve so?is in steam, in =arts =er mi??ion s
S O Steam A?o rate, in =ouns =er 2our C O #ota? isso?ve so?is in rum ater, in =arts =er mi??ion @
B
O "ontinuous @?oon A?o rate, in =ouns =er 2our
Usin t2e a@ove re?ations2i=s an assumin no carryover, t2e minimum @?oon rate may @e etermine Arom t2e maDimum rum ater tota? isso?ve so?is as Ao??os
For a =articu?ar a==?ication, t2e ty=e oA Aee ater treatment se?ecte esta@?is2es Aee ater so?is concentration
(;3 #o =rovie Aor steam rum ater c2emistry contro?, t2e rum is =rovie it2 t2e Ao??oin Aaci?ities a ( Aee ater =i=e =erAorate to even?y istri@ute Aee ater over t2e ?ent2 oA t2e rum @ #2e c2emica? Aee =i=e, simi?ar in esin to t2e Aee ater =i=e, an usua??y near t2e Aee ater =i=e to =romote miDin c #2e continuous @?oon =i=e, a =erAorate =i=e ?ocate in t2e rum near t2e ?o ater ?eve? 2ose Aunction is to contro? t2e tota? isso?ve so?is ?eve? oA t2e @oi?er ater an t2ere@y t2e steam =urity #2is area is 2ere rum ater so?is are Mue to @e most etrimenta? to steam =urity $A t2e ?eve? ro=s @e?o t2e ?o ?eve?, continuous @?oon ceases @ut ?eve? ro= rate is reuce $A =ossi@?e, t2e continuous @?oon =i=e s2ou? @e ?ocate 2ere t2e @oi?er ater tota? isso?ve so?is ?eve? is 2i2est to reuce @?oon rates $ntermittent @?oon $A t2e rum 2as unistur@e ones at its @ottom, a co??ector can @e use to remove so?is 2ic2 =reci=itate Arom t2e rum ater %t2erise, a mu rum or a ?o ve?ocity 2eaer ?ocate at a ?o e?evation in t2e circu?ation system can @e use Aor intermittent @?oon ?ocation
(PPE&.$0 B ' HE(# FLU0 (&. "$R"UL(#$%& R(#$% B1 Genera? "ircu?ation, 2eat A?uD, an @oi?in A?o reimes are Aunamenta?s a ==?ica@?e to a?? HRSGs, rear?ess oA 2et2er t2e system is Aorce or natura? circu?ation, atertu@e o r Airetu@e esin
B) Heat F?uD B)1 F$L! B%$L$&G Heat A?uD is t2e 2eat transAer rate =er unit area oA tu@e surAace measure at t2e surAace 2ere @oi?in occurs $A 2eat A?uD is eDcessive, steam is enerate so ra=i?y t2at a steam Ai?m is Aorme at t2e tu@e a?? #2is steam Ai?m is=?aces t2e ater an Cee= s it Arom reettin t2e tu@e #2is =2enomenon is Cnon a s Ai?m @oi?in or e=arture Arom nuc?eate @oi?in an resu?ts in a suen increase in t2e tu@e meta? tem=erature #2is can cause tu@e Aai?ure resu?tin Arom 2i2 meta? tem=erature #2e 2eat A?uD at 2ic2 e=arture Arom nuc?eate @oi?in occurs e=ens on severa? varia@?es inc?uin a %rientation an eometry oA t2e surAace @ 7uantity oA steam in t2e ater c Steamater miDture ve?ocity Pressure #2e maDimum 2eat A?uD a??oe in HRSG esin s2ou? @e @ase on t2e most strinent com@ination oA t2ese varia@?es
B)) &U"LE(#E B%$L$&G Since @oi?in 2eat transAer coeAAicients are muc2 reater t2an t2ose on t2e 2ot as sie, tu@e meta? tem=eratures a==roac2 t2at oA t2e saturate ater #2is assumes nuc?eate @oi?in 2ere steam @u@@?es enerate at t2e tu@e a?? are a?ternate?y is=?ace @y ater reettin t2e tu@e Steam @?anCetin can a?so occur at ?o 2eat A?uDes it2 nuc?eate @oi?in iA t2e Aormin steam @u@@?es are not continuous?y remove Hoever, at 2eat A?uDes a@ove 4, Btu2our'Aoot suare, nuc?eate @oi?in c2anes to Ai?m @oi?in (t t2is =oint even t2e most viorous circu?ation cannot =revent t2e Aormation oA an insu?atin steam Ai?m on t2e 2eatin surAace
B)3 L%"(L HE(# FLU0
#a@?e B'1 s2os ty=ica? ranes oA maDimum a??oa@?e ?oca? 2eat A?uDes #2e maDimum 2eat A?uD s2ou? @e ca?cu?ate in t2e area oA 2i2est tem=erature iAAerence @ase on A?ui =ro=erties at t2at tem=erature an uner c?ean conitions Bot2 tu@ea?? tem=erature an 2eat A?uD s2ou? @e ana?ye to etermine t2e o=eratin ?imits Aor t2e HRSG
!any inustria? HRSG esins 2ave muc2 ?oer ?oca? 2eat A?uDes t2an t2e maDimum s=eciAie in #a@?e B'1 #2is may @e ue to ?o tem=erature iAAerence or ?o overa?? 2eat transAer coeAAicients
B3 "ircu?ation B31 "$R"UL(#$%& R(#$% #2e circu?ation ratio "R: is t2e ratio oA tota? steamater A?o in t2e circuit to t2e steam A?o at t2e eDit oA t2e riser
#2e esiner sets t2e circu?ation ratio to maintain nuc?eate @oi?in Aor a?? o=eratin conitions, t2at is, to avoi e=arture Arom nuc?eate @oi?in Hoever, corrections Aor to'=2ase A?o reime s2ou? @e use in conMunction it2 circu?ation ratio rat2er t2an mere?y s=eciAyin minimum circu?ation ratio Bu@@?e A?o is t2e reuire to =2ase A?o reime Aor HRSG tu@es Bar'"o2en, Ruer, an GriAAit2 Aoun t2at unesire stratiAie or =?u A?o reimes are =ossi@?e 2en circu?ation A?o is eit2er too ?o or 2eat A?uDes too 2i2 #aite? an .uC?er =resent a moe? =reictin A?o reimes as a Aunction oA tu@e iameter an orientation, A?ui =ro=erties an steamater mass ve?ocity
B3) &(#UR(L "$R"UL(#$%&
HRSG risers an oncomers Aorm a A?o circuit @y con nectin t2e steam rum at t2e to= an a mu rum or 2eaer at t2e @ottom .urin o=eration, t2e steamater miDture in t2e risers is ?ess ense t2an t2e ater in t2e oncomers F?o occurs it2in t2e circuit at a rate 2ere t2e iAAerence in static 2ea @eteen t2e risers an oncomers @a?ance t2e resistance to A?o ( ty=ica? natura? circu?ation circuit ty=ica??y 11 to 151 ater to steam ei2t ratio: is s2on in Fiure B'1 #2e circu?ation ratio e=ens on t2e static 2ea iAAerences, resistance to A?o in t2e circuit, system =ressure, an uantity oA steam enerate #2e esiner can increase circu?ation ratio @y raisin t2e 2ei2t oA t2e steam rum anor @y reucin A?o resistance, Aor eDam=?e, ?arer oncomers or increase A?o area ( ty=ica? =erAormance curve Aor a =articu?ar system is s2on in Fiure B') #2is curve s2os t2at an increase in t2e 2eat transAer an steam eneration rate ecreases t2e circu?ation ratio #2e circu?ation ratio s2ou? @e ca?cu?ate Aor t2e antici=ate rane oA o=eration Lo circu?ation ratio can resu?t in e=arture Arom nuc?eate @oi?in an tu@e over2eatin &atura? circu?ation HRSGs enera??y use vertica? or inc?ine tu@es to a??o steam to rise Aree?y
B33 F%R"E. "$R"UL(#$%& Force circu?ation HRSGs use a =um= to maintain circu?ation t2rou2 t2e steam eneratin tu@es oA t2e eva=orator, steam rum an 2eaers ( ty=ica? Aorce circu?ation circuit ty=ica??y 51 ater to steam ei2t ratio: is s2on in Fiure B'3 -ater is istri@ute to =ara??e? tu@e circuits Arom an in?et 2eaer an t2e eDitin steamater miDture is co??ecte in an out?et 2eaer #2e steamater miDture is returne to t2e steam rum 2ere t2e steam is se=arate an ater is recircu?ate to t2e eva=orator Steam enerator tu@es may 2ave any orientation Fire 2eater a==?ications are usua??y 2orionta? #u@es are connecte in series in a ser=entine arranement to Aorm eac2 sin?e tu@e =ass -it2 t2is arranement ater A?os u=ar an im=roves A?o sta@i?ity @eteen mu?ti=ass =ara??e? circuits #2e @uoyancy oA t2e to =2ase A?o assists t2e Aorce circu?ation an minimies t2e =otentia? Aor steam =ocCetin Force circu?ation HRSGs enera??y 2ave ?arer tu@es, ?oner tu@e circuits, an 2i2er A?o resistance t2an natura? circu?ation HRSGs
B34 (.*(&#(GES (&. .$S(.*(&#(GES B341 &atura? circu?ation avantaes are a &o =um=in systems are reuire @ Less maintenance c !ore re?ia@?e
B34) &atura? circu?ation isavantaes are
a Usua??y restricte to vertica? or inc?ine tu@e a==?ications @ Usua??y insta??e at rae, t2us, more =?ot s=ace is reuire c Steam rum ?ocation reuires 2i2er e?evation
B343 Force circu?ation avantaes are a Horionta? or vertica? tu@e arranements may @e use @ Force circu?ation arranements can @e insta??e in vertica? 2eater A?ue as ucts c Sma??er =?ot reuirements #2e steam rum ?ocation is not restricte
B344 Force circu?ation isavantaes are a Pum=in systems are reuire @ Hi2er maintenance ue to =um=s c *ertica? tu@e arranements reuire esin eD=ertise
(PPE&.$0 " ' S%%#BL%-ERS
"1 Genera? "11 F?ue as sie tu@e c?eanin evices are =rimari?y @?oin meia c?eaners or soot@?oers Sonic c?eanin an s2ot c?eanin are se?om use #2is a==eniD i?? aress on?y soot@?oers
"1) Soot@?oers are eit2er AiDe =osition rotary or retracta@?e Retracta@?e soot@?oers may @e eit2er Au??y or =artia??y retracta@?e
"13 FiDe =osition rotary soot@?oers 2ave a mu?tino?e e?ement =ermanent?y ?ocate it2in t2e A?ue as stream #2e e?ement is su==orte at @ ot2 ens an it2in t2e A?ue as stream @y @racCets usua??y attac2e to t2e tu@es
"14 Retracta@?e soot@?oers 2ave a ?ance t2at norma??y contains to no?es, 1; erees o==ose an ?ocate at its en #2e ?ance traverses across t2e tu@e @anC 2i?e rotatin #2e c?eanin action is =rouce @y irectin t2e Mets oA @?oin meia in a 2e?ica? =at2 across t2e tu@e @anC
"15 Soot@?oers are =?ace in ?anes @eteen ros oA tu@es #2e soot@?oer ?ane is t2e Aree s=ace @eteen t2e nearest ro oA tu@es u=stream an onstream oA t2e c?eanin e?ement See Fiure "'1:
") (==?ication ")1 Soot@?oers are reuire 2en 2eavy oi? is Aire an eDtene surAace tu@es stus or Ains: are =resent Provisions Aor Auture c?eanin are reuire 2en 2eavy oi? is Aire an on?y @are tu@es are =resent Suc2 =rovisions can inc?ue soot@?oer ?anes or mec2anica? c?eanin ca=a@i?ity
")) Soot@?oers are reuire 2en cata?yst @earin a ses are =resent
")3 Provisions Aor Auture c?eanin s2ou? @e consiere 2en ?i2t oi? may @e Aire
")4 Fue? as Aire units o not norma??y reuire c?eanin #2e Aue? as com=osition s2ou? @e reviee Aor Aou?in =otentia? an Auture =rovision Aor soot@?oers mae 2en t2ere is a remote =ossi@i?ity oA Aou?in
")5 -2en ammonia an su?Aur com=ouns are =resent, t2e =otentia? Aor Aou?in an =o ssi@?e soot@?oer use s2ou? @e consiere
")/ For tem=eratures over 1F, a com@ination oA retracta@?e an rotary @?oers may @e esira@?e ue to t2e =otentia? oDiation an roo=in oA t2e rotary soot@?oers e?ement
"3 System "onsierations "31 HRSG .ES$G& "311
$nterna? reAractories s2ou? @e =rotecte Arom amae @y t2e @?oin meia Protection may inc?ue eit2er meta??ic s2rous or ense casta@?e ?inin Aor t2e c?eanin ?ane an im=inement area or Aor t2e entire tu@e @anC
"31) $ns=ection oors s2a?? @e =rovie in t2e ?anes to =ermit ins=ection oA t2e tu@e surAaces
"313 #u@e arranement an eDtene surAace c2oice an orientation s2ou? @e com=ati@?e it2 t2e c2oice oA soot@?oer
"314 #2e num@er oA ros oA soot@?oers an t2e sie oA t2e soot@?oer ?anes s2ou? accommoate t2e c?eanin c2aracteristics oA t2e soot@?oer use
"315 #2e interAerence oA tu@e su==orts, uies, an @aAA?es must @e consiere 2en ?ayin out c?eanin evices
"31/ #2e @?oin meia may @e steam or air #2e manuAacturer s2ou? @e consu?te a@out t2e o=timum =ressure %=eration at =ressures ?oer t2an t2ose recommene @ y t2e manuAacturer ecreases t2e c?eanin a@i?ity oA t2e soot@?oer B?oin =ressure is ty=ica??y 1 =ouns =er suare inc2 aue to 3 =ouns =er suare inc2 aue
"3) F$0E. P%S$#$%& R%#(R+ S%%#BL%-ERS "3)1 Rotary soot@?oers mounte on o==osin sies oA t2e tu@e @anC are reuire iA t2e tu@e @anC eDcees 15 Aeet
"3)) Soot@?oer ?anes s2ou? @e a minimum oA 35 inc2es c?ear @eteen tu@e outsie iameters Aor @are tu@e a==?ication, 1 inc2es @eteen t2e ti=s oA Ains or stus 2en t2e soot@?oer e?ement is =ara??e? to t2e tu@es, 1; inc2es 2en t2e e?ement is =er=enicu?ar to t2e tu@es
"3)3
Soot@?oer rotation may @e manua? or mec2anica? rive, suc2 as a =neumetic or e?ectric motor #2e e?ement, com@ination ear rive, an cam actuate @?oin meia amission va?ve are s2on in Fiure "')
"3)4 #y=ica? as tem=erature ?imits Aor e?ement materia?s are a "ar@on stee? ;F @ "2rome =?ate or ca?orie stee? 1F c Stain?ess stee? )) =ercent "r minimum: 15F
"3)5 Su==ort @racCets t2at are attac2e to tu@es s2ou? @e oA t2e same materia? as t2e e?ement $A t2e @racCet tem=erature eDcees 11F an t2e vanaium content oA t2e Aue? eDcees 5 =arts =er mi??ion, 5 "r'5 &i "@: @racCets s2a?? @e use
"3)/ #2e su==ort @racCets s2a?? not @e attac2e to t2e e?ement
"3)K Su==ort @racCet s=acin is a Aunction oA A?ue as tem=erature #y=ica? s=acin ?imitations are a 4 inc2es a=art 9F @ 3 inc2es a=art 15F c ) inc2es a=art 1;F
"3); #2e num@er oA no?es Aor a =er=enicu?ar e?ement ty=ica??y s2on @y Fiure "') is @ase on =roviin one no?e =er s=ace @eteen tu@e ros (Ater esta@?is2in t2e num@er oA no?es, t2e @?oin meia consum=tion =er e?ement may @e estimate Arom Fiures "'3 or "'4 (ctua? consum=tion rates are a Aunction oA soot@?oer construction etai?s #o =rovie aeuate coverae Aor most inustria? a==?ications,
mu?ti=?e e?ements are norma??y insta??e
"33 RE#R("#(BLE S%%#BL%-ERS "331 "?eanin ?anes Aor @are tu@es s2ou? @e a minimum oA 15 inc2es c?ear @eteen tu@e outsie iameters "?eanin ?anes Aor eDtene surAace tu@es s2ou? @e 1; inc2es @eteen t2e ti=s oA Ains or stus 2en t2e soot@?oer e?ement ?ance: is =ara??e? to t2e tu@es an )4 inc2es 2en t2e e?ement is =er=enicu?ar to t2e tu@es
"33) #2e soot@?oer is su==orte at t2e casin a?? @y a s?eeve yoCe an Arom a =?atAorm or structure outsie t2e casin near t2e out@oar en Fiure "'5 s2os a ty=ica? su==ort arranement
"333 Positive =ressure a?? s?eeves it2 sea?in air are reuire to =revent A?ue as ?eaCs in =ositive =ressure HRSGs
"34 S%%#BL%-ER SP("$&G "341 #2e s=acin oA soot@?oer e?ements s2ou? @e @ase on t2e eAAective c?eanin raii #2e eAAective c?eanin raii is a Aunction oA t2e Ao??oin a #u@e @anC tem=eratures
@ B?oin meia c B?oin meia =ressure &o?e sie an num@er e Fue? c2aracteristic =otentia? Aor soot Aormation: A #u@e arranement =itc2: an sie EDtene surAace ty=e an orientation 2 %rientation oA soot@?oer e?ement to tu@es i #y=e oA HRSG
"34) #y=ica? soot@?oer s=acin Aor staere tu@e @anCs e=ens on 2et2er t2e soot@?oer is a rotary or a retracta@?e one For rotary soot@?oers, t2e maDimum 2orionta? or vertica? coverae is 3 Aeet Arom t2e e?ement or 3 tu@e ros, 2ic2ever is ?ess For retracta@?e soot@?oers, t2e maDimum 2orionta? or vertica? coverae is 4 Aeet Arom t2e e?ement or 4 tu@e ros, 2ic2ever is ?ess Hi2 Aou?in Aue? i?? reuire more soot@?oers #2e soot@?oer venor s2ou? @e consu?te Aor 2is recommenations Aor t2e s=eciAic system an its eAAective c?eanin raii
"35 E0#ER&(L P$P$&G Soot@?oer eDterna? =i=in arranements s2ou? inc?ue t2e Ao??oin a $niviua? @?ocC va?ves to eac2 @?oer @ -arm u= =i=in c Steam @?ees Steam tra=s
"3/ "%&#R%LS Loca? startsto= =us2 @utton stations, main steam contro? va?ve, an seuentia? contro? =ane? are norma??y =rovie @y t2e soot@?oer manuAacturer
"4 (vantaes "41 F$0E.'P%S$#$%& R%#(R+ S%%#BL%-ERS #2e avantaes oA AiDe'=osition rotary soot@?oers inc?ue a "onstruction is ?ess com=?eD @ EDterna? =?atAorms an structure are minimie
"4) RE#R("#(BLE S%%#BL%-ERS #2e avantaes oA retracta@?e soot@?oers inc?ue a #2e ?ance can @e use at any A?ue as tem=erature @ $nterna? su==orts are not reuire Aor t2e ?ance c !ore eAAective c?eanin is =rovie t2an it2 AiDe'=osition rotary soot@?oers
Feer soot@?oers are reuire t2an it2 AiDe'=osition rotary soot@?oers
"5 .isavantaes "51 F$0E.'P%S$#$%& R%#(R+ S%%#BL%-ERS #2e isavantaes oA AiDe'=osition rotary soot@?oers inc?ue a E?ements are continua??y eD=ose to t2e A?ue ases @ !ore Areuent maintenance is reuire t2an it2 retracta@?e soot@?oers c #2e c?eanin raius is s2ort
