CPB30004 Process Dynamics and Control Experiment 4: Gas pressure process control lab report

CPB30004- Process Dynamics and Control Experiment 4: Gas Pressure Process Control

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SUMMARY

!e o"#ecti$es o% t!is experiment o% Experiment 4 Gas Pressure Process Control &ere to identi%y t!e important components o% t!e air pressure control system and to mar' t!em in t!e P()D* to study single loop %lo& control using P)D controller* to control t!e pressure in single capacity and t&o capacity processes using P)D controller and to tune t!e P)D controller using +iegler ,ic!ols closed-loop met!od !e procedure started &it! general procedure and t!e main procedure !a$e t!ree trial &!ere in %irst trial* P)D controller is set &it! $alues o% PB1. /0* 11. 40 sec and D1. 0 sec and controller is set to mode uto 2 and t!en a%ter t!e response is sta"le* it is s&itc!ed to mode manual 2 to decrease 5-10 o% 6 and is s&itc!ed to uto 2 mode again !e same procedure is repeated %or second and t!ird trial &!ere in second trial* PB1. 45* 11. 10 sec and D1. 0 sec &!ile in t!ird trial* PB1. 70* 11. 10 sec and D1. 7 sec Based on t!e c!art c! art o"tained in 8igure 8igure 41* and and re%errin re%erring g to t!e +iegler-,ic!ols9 Closed oop et!od explanation on sta"ility o% system* &e can say t!at t!e process is sta"le* as t!e amplitude o% t!e cur$es does not $aries so muc!* and t!e cur$es also oscillated at t!e same %re;uency %or eac! trial o% process E$en t!oug! t!e results o"tained s!o&s t!at t!e process &as oscillating accordingly and %re;uently* !o&e$er* !o&e$er* di%%erent trials !a$e di%%erent $alues o% proportional "and 2PB !us* t!e +iegler-,ic!ols9 Closed Closed oop et!od &as pro$ed !e met!od itsel% de$eloped t!eir turning rules "y stimulating stimulating a great num"er o% di%%erent processes and correlating t!e controller parameters &it! %eatures o% t!e step response !eoretically* t!e t!e !ig!er t!e proportional "and 2PB $alues* t!e lo&er t!e control gain 2
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1.0 INTROD INTRODUCT UCTION ION

Pressure $essels %unction is to to store and transmit li;uid* gas or $apours under controlled pressure Pressure $essels played an important role role in c!emical and mec!anical industries as a storage $essels %or gas p!ase components* reactions $essels to carry out a gas p!ase reaction* "ecause it &ill exert pressure e;ually in all directions o% t!e &alls &alls and ends o% pressure $essels )n pressure $essels* $essels* it is is necessary %or precise control o% pressure to maintain maintain constant concentration o% components in $essels* maintain num"er o% moles in $essels and to protect $essel %rom "eing damaged due to a $ery !ig! pressure !e t&o main types o% pressure pressure $essels are according to t!e end construction and according to t!e dimensions )n engineering t&o main s!apes o % t!e $essels can "e %ound is cylindrical c ylindrical tan' $essel or sp!erical tan' $essels )n t!is process* t!e t!e plant consists o% t&o t&o pressure $essels &!ic! &!ic! are >1 an >7 &it! piping %or t!e %lo& o% gas or $apour* $al$es to control t!e %lo&s and %itting !e process plant consists o% pressure control $al$e 2PC6* eac! $essel !as its o&n $ent 26* and "ottom drain 2D* 2D* air pressure regulator 2? and pipelines P )n single capacity process* only $essel $essel >1 is used &!ile $essel >7 is "y-passed ean&!ile* %or t&o capacity process* t&o $essels* >1 and >7 &ere u sed )t is important to %ully understand t!e piping and instrument diagram 2P()D o% t!e process "e%ore conducting t!e experiment to ensure t!e steps is done correctly !eoretically* %or t!is process* t!e +iegler-,ic!ols9 Closed oop et!od is used )n t!is met!od* t!e ratio o% t!e amplitudes o% su"se;uent pea's in t!e same direction is approximately 1@4: A 2 A 2 A 1 A 1

.

1 4










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PROCEDURE •

A?A?-P P P?CED?E P?CED ?E 1 !e %irst %irst step step &as &as to to s&it s&itc! c! P,E* P,E* ACD@DDC selector s&itc! and s&itc! on t!e main po&er supply 7 !e po&er supply supply &as &as s&itc!ed s&itc!ed , !e !e C<, C<,EDGE EDGE "utton "utton &as &as pressed pressed to silence t!e "uFFer 3 !e instrument instrument air supply regulator regulator &as &as set to to t!e pressure pressure indicated indicated at t!e t!e air regulators at t!e pneumatic control $al$es PC6>1 and PC6>7 4 !e "y-pass "y-pass $al$es $al$es around around t!e t!e control control $al$es $al$es PC6>1 PC6>1 and PC6>7 &ere &ere s!ut s!ut and t!e pair o% manual $al$es upstream@do&nstream o% t!ese control $al$es &ere opened 5 !e contro controll $al$e $al$e position positioner er 2PP 2PP o% PC6>1 PC6>1 &as &as ,  !e compressed compressed air &as &as a$aila"le a$aila"le at t!e t!e pressure pressure inlet air air regulator regulator ?>1 / !e $ent $al$e 26 26 and "ottom "ottom drain drain $al$e $al$e 2D o% $essel $essel >1 >1 &ere s!ut s!ut H 6al$es 6>1B 6>1B and and 6))) 6))) &ere s!ut s!ut manual manually ly > !e proces processs inlet inlet manual manual $al$e $al$e 6>1 6>1 &as s!ut s!ut %ully %ully 10 !e panel controller controller P)C>1 P)C>1 &as put in manual (M) mode and t!e 6 &as ad#usted to - 3 so t!e control $al$e PC6>1 opened 11 11 !e %inal disc!arge disc!arge manual $al$e 26P &as opened %ully %ully 17 Pipelines P) 2Aingle 2Aingle capacity process process opened and P)) at t!eir $arious manual $al$es 13 !e manual "y-pass $al$e B>7 around $essel >7 >7 &as opened anual $al$es at t!e inlet 6) and outlet 6>7 o% >7 &ere s!ut 14 6al$es 6al$es 6>7 and and 6>7B &ere "ot! s!ut 15 Pressure at ?>1 ?>1 &as ad#usted 6>1 &as %ully s!ut s!ut 1 6>1 &as opened opened and regulated until until t!e %lo& rate at t!e $aria"le area area %lo& meter 8)>7 reads 35 Nm3/Hr. 1/ C!ec' t!e pressure pressure and and %lo& rate setting: a. PC6>1 %rom P)C>1 &as set in manual (M) mode &it!

6.103 !e pressure at $essel >1 must "e around 77 I 7/ psig b. PC6>1 %rom P)C>1 &as set in manual (M) mode &it! 6.-3










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,@88 P?EAA?E C,? 1 !e c!art dri$e o% t!e recorder recorder &as starte started d "y pressing pressing t!e J?CDK pus!"utt pus!"utton on 7 PC6>1 PC6>1 %ro %rom m P)C>1 P)C>1 &as &as s!ut s!ut in in manual (M) mode &it! 6.103 !e pressure at P6 at P)C>1 &as "et&een "et&een t!e range o% 77-7/ psig 3 P)) &as &as opened t!roug! t!roug! t!e t!e manual disc!ar disc!arge ge glo"e $al$e $al$e 6>7 6>7 at t!e common common $ent o% P)) !e gate $al$e 6>7B at P)) &as closed 4 !e response response o% P>1 P>1 at t!e t!e recorder recorder P?>1 &as noted PC6>7 PC6>7 &as &as opened opened &!en &!en P>1 exceeds 71 psig and closed closed &!en P>1 drops "elo& a %ixed Dead Band 205 psig* psi g* ie* ie * 705 70 5 psig p sig 5 !e ,@88 ,@88 action action &as repeated repeated "y opening opening and closing closing o% PC >1 "y reducin reducing g t!e 6 suc! t!at pressure P6 drops "elo& 70 psig !en s!ut PC6>1 %ully again &it! 6 . 103  !e record record c!art dri$e dri$e &as stopped and and t!e rele$ant rele$ant portions portions o% t!e c!art c!art &as retrie$ed P)D C,? 8 P?EAA?E ), A),GE CPC)= P?CEAA 1 !e c!art dri$e o% t!e recorder recorder &as starte started d "y pressing pressing t!e J?CDK pus!"utt pus!"utton on at t!e 7 3 4 5

%ront o% t!e recorder Pipeli Pipelines nes P) P) and P)) P)) &ere &ere opened opened t!roug!o t!roug!out ut Glo"e $al$e $al$e 6>7 at t!e common common $ent o% P)) &as opened opened manually manually Gate $al$e $al$e 6>7B 6>7B at at t!e common outlet o% P)) P)) &as &as closed closed 6essel >1 >1 &as used %or %or single single capacity capacity operati operation on a By-pas By-passs $al$e $al$e B>7 B>7 around around >7 &as &as opene opened d " !e manual man ual $al$es $al $es at t!e inlet* inl et* 6)* and at t!e outlet* out let* 6>7* 6> 7* o% >7 &as s!ut c !e air %lo& %lo& pat! pat! >1-P) >1-P)-8) -8)>7>7-PC6 PC6>1>1-6P 6P &as &as opened opened t!roug! B>7

 !e set set point point o% o% P)C>1* P)C>1*A6 A6 &as &as set at 15 psig psig / P)D controller controller &it! &it! t!e %irst %irst 2) trial trial $alues: $alues: PB1 &as set set at /0* 11 11 . 40 secs* secs* D1 . 0 sec










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> P)C>1 P)C>1 &as s&it s&itc!e c!ed d to to Manual 2 mode and decrease 6 "y a"out 5 to 10 !en* s&itc! "ac' to AUTO 2 10 !e response &as slo& so return t!e set point A6 . 15 psig and reduced t!e )1 to to 70 secs and repeat t!e step 2> again 11 11 !e P)D controller controller &as set &it! t!e "#$!n% 2)) trial $alues: PB1 . 45* )1 . 30 secs* D1 . 0 sec 17 P)C>1 &as s&itc!e s&itc!ed d to Manual 2 mode* t!e 6 &as decreased to 5 to 10* s&itc!ed "ac' to Au! 2 mode and t!e response &as o"ser$ed %or a %e& minutes !e response &as oscillatory 13 PB1 &as increased "y 5 ?epeat t!e step 211 211 14 !e t!ird 2))) trial $alues %or t!e P)D controller: PB 1 . 70* )1 . 10 secs* D1 . 7 sec 15 !e distur"ance &as introduced in 6 6 and t!e response response &as o"ser$ed 1 !e c!art dri$e &as stopped stopped and t!e rele$ant portions o% t!e c!art paper &as retrie$ed

ALD, P?CED?E 1 !e controller controller P)C>1 P)C>1 &as s&itc!e s&itc!ed d to anual2 anual2 mode* mode* and t!e 6 6 &as set set to 100 100 7 Pus! Pus! t!e recor recorder der M?CDN M?CDN "utto "utton n to stop stop recordi recording ng 3 !e main main po&e po&err supply supply &as s&itc! s&itc!ed ed o%% o%% &.0 RESU'TS  CA'CU'ATIONS &.1 PIPIN  INSTRUMENT DIARAM










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&.* START+UP PROCEDURE REPORT

)n a start-up start-up procedure "e%ore starting starting t!e Gas Pressure Process Control Control experiment* t!e MP,E* MP,E* ACD@DDCN selector s&itc! &as s&itc!ed to MP,E* ACDN position !e main po&er supply &as s&itc!ed , !e O?CD9 "utton &as pressed to stop t!e recorder dri$e %rom running and OC<,EDGE9 "utton &as pressed to silence t!e "uFFer &!en annunciator gets acti$ated !e instrument air air supply regulator &as set to pressure indicated indicated at air regulators at pneumatic pneumatic control $al$es PC6>1 and PC6>7 !e purged &ater in air regulators &as purged "y opening t!e












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pressure inlet air regulator ?>1 &as ensured !e $ent $al$e 26 and "ottom drain $al$e 2D o% $essel >1 &as c!ec'ed to ensure it is s!ut !e manual $al$es 6>1B and 6 and process inlet manual $al$e 6>1 &ere &ere s!ut %ully %ully !e panel controller P)C>1* &as placed in manual (M) mode and its 6 &as ad#usted to 6 . -3 to open control $al$e PC6>1t!e %inal disc!arge manual $al$e 26P &as open %ully !e t&o pipelines P) an P)) &ere traced in t!e process air supply as %ollo&ing: P,-#l,n# P'I single capacity process:

?>1-6>1->1-P)-B>7-8)>7-PC6>1-6P P,-#l,n# P'II

?>1-6>1->1-P))-6))-PC6>7-6>7-6>7B-6 !e pipelines P) 2Aingle capacity process and P)) &ere opened %ully at t!eir $arious manual $al$es !e manual "y-pass $al$e B>7 around $essel >7 &as ensured opened and manual $al$es at inlet 6) and outlet 6>7 and >7 &ere ensured s!ut A!ut "ot! $al$es 6>7 and 6>7B !e pressure at ?>1 is approximately at pressure indicated at ?>1 &as c!ec'ed and ad#usted* 6>1 &as %ully s!ut 6>1 &as t!en slo&ly op en and regulated* until %lo& rate at $aria"le area %lo& meter 8)>7 s!o&ed reading o% 35,m3@Lr astly* t!e pressure and %lo& rate setting setting &ere c!ec'ed: a PC6>1 and and P)C>1 &as &as s!ut s!ut %ully %ully in manual manual 2 2 mode &it! &it! .103 .103 !e










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)n a process dynamic ( control* it is important important to understand understand t!e terms in response cur$e cur$e understanding t!e terms in t!e response cur$es can !elp in determine &!at is a setpoint* and &!at is dead"and Aetpoint in a process control means desired or target $alue %or an essential $aria"le o% a system* o%ten used to descri"e a standard con%iguration or norm %or system Dead"and is a period o% dead state o% a system 2sometimes called neutral Fone or dead Fone is an inter$al o% signal domain or "and &!ere no action occurs 2system is dead or output is Fero )n Gas Pressure Pressure Process Control Control experiment* t!e setpoint %or P)D Control o% Pressure in Aingle Capacity Process &as A6.15 psig !e distur"ance &as introduced to t!e process to o"ser$ed t!e c!ange in oscillatory Distur"ance is a $aria"le* an e%%ect o% surrounding to&ards t!e process t %irst trial* t!e P)D controller &as set as "elo&: PB1./0* )1.40 secs* D1.0 sec During t!is trial* a%ter t!e distur"ance &as introduce to t!e process* t!ere are no constant oscillation and t!e c!art print out a dead d ead "and* &!ere t!e system &as in a dead state or neutral Fone !e $alue o% )1 &as t!en reduced to 70 seconds and t!e process &ere repeated to o"ser$e t!e c!anges %ter t!e c!anges o% $alues )1 reduced to 70 secs* t!e c!art dri$e print out a constant oscillation &it! constant %re;uency* !o&e$er t!e amplitude &as not constant !e experiment &as t!en prepared %or t!e second trials* &!ere t!e $alues &ere set as s!o&n "elo&: PB1.45* )1.30 secs* D1.0 sec










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!e results in t!e c!art paper s!o&s t!at t!e response cur$es &ere oscillating at constant oscillations E$en a%ter t!e distur"ances &as introduced* t!e cur$es s!o& no e%%ect and t!e controller managed to operated accordingly "y re#ecting t!e distur"ances and %orce "ac' t!e process to t!e setpoint o% t!e process

&.& RESPONSE RES PONSE CURES OR SIN'E CAPACITY  TO+CAPACITY TO+CAPACITY

,2ur# &.1 S,n2l# $a-a$, -r!$#"" r#"ul"

8or single capacity process* only $essel >1 &as used and $essel >7 &as "y-passed !e set point o% P)C1 &as set to 15 psig %ter %ter setting t!e P)D controller &it! &it! $alues o% PB1 to /0* )1 to 40 seconds and D1 to 0 second* t!e controller &as set to uto 2 mode and &ait %or response to "ecome sta"le By sta"le* it means t!at t!e oscillation o% t!e cur$es &as oscillating










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trial &as almost t!e same* it is oscillating at constant %re;uency "ut a slig!t di%%erence in amplitude can "e seen !en t!e distur"ance &ere introduced to t!e process* t!e process &ere not a%%ected and still operate as usual astly* t!e t!ird trial trial %or single single capacity process &ere operate* &it! t!e parameter $alues "eing c!ange to PB1.70* )1.10 secs* D1.7 secs During t!is trial* t!e response cur$e oscillated at t!e same %re;uency as t!e %irst and second trial* "ut same amplitude as t!e second trial )n t!is process* t!e distur"ance also did not a%%ect t!e process and t!e controller a"le to operate correctly E$en t!oug! t!e results o"tained o"tained s!o&s t!at t!e process &ere oscillating accordingly and %re;uently* !o&e$er* !o&e$er* di%%erent trials !a$e di%%erent $alues o% proportional "and 2PB !eoretically* t!e t!e !ig!er t!e proportional "and 2PB $alues* t!e lo&er t!e control gain 2
PB

100 =

K c

M)% t!e operating point $aries and i% i% t!e process dynamic properties depends on t!e operating point* you s!ould consider using adapti$e control or gain sc!eduling* &!ere t!e P)D parameter are ad#usted as %unctions o% t!e operating point )% t!e controller parameters s!all !a$e %ixed $alue* t!ey s!ould "e tuned in the worst case as stability is regarded. This ensures proper stability if the operation point varies. The worst operating point is the









CPB30004- Process Dynamics and Control Experiment 4: Gas Pressure Process Control A 2 A 2 A 1 A 1

.

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1 4

Lo&e$er* t!ere is no guaranty t!at t!e actual amplitude ratio o% a gi$en control system "ecomes 1@4 a%ter tuning &it! one o% t!e +iegler and ,ic!ols9 met!ods* met!ods* "ut it s!ould not "e $ery di%%erent %rom 1@4N 2Laugen* 7010

,2ur# &.* A$$!r%,n2 ! 4,#2l#r+N,$!l6 ,7 A*/A1 8 9 # -r!$#"" !r "ab,l, !7 ""#m ," O:












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ANA'YSIS

Pressure $essels are use as storage $essels %or gas p!ase components Precise control o% pressure in t!e pressure $essels is necessary in order to maintain a constant concentration o% components in t!e $essel and maintain t!e num"er o% moles in t!e $essel !e %lo& o% air &as o"ser$ed "y manipulating t!e parameters Considering* t!at t!is is a single capacity process and certain amount o% pressure &as applied* &e are re;uired to use a proper control to t!e $al$e manually 8or t!is experiment &e are using pneumatic control










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DISCUSSION

)n t!is process* &e are a"out to ma'e an o"ser$ation a"out %lo& o% air a ir &!en certain parameter !ad "een manipulated Parameter t!at !ad "een c!anged during t!is process is $alue o% 6 to get $alue o% P6 "elo& t!an 70 psig t!er parameters t!at need to c!ange are $alues o% PB1* 11* D1 and also c!ange t!e process %rom manual to auto )n t!is experiment* &e only conduct control o% pressure in single capacity process










P a g e | 14

8igure 1: ir-to-open and ir-to-close control $al$e

Basically* t!ese t!ese type o% control $al$e using a same mec!anical to operate !e important mec!anism is t!e diap!ragmS &!ic! contain upper and lo&er c!am"er* t!e springS located










P a g e | 15

sometimes &e need to c!ange t!e set point immediately due to current situations "ut on @ o%% only &or's to open or close %inal control element !us* a set o% "oundaries need to "e introduce to protect t!e %inal control element %rom "ecome &ear !is set o% "oundaries is calling a dead "and )t is a range operation around set point and !a$e lo&er and upper "oundary it!in it!in t!is limitation* dead "and &ill reduce t!e &ear &ea r o% %inal control element and t!e c!anges c!ang es can "e easily ma'es &it!out damage t!e instrument

8igure 7: ?ange o% dead "and










P a g e | 1

CONC'USION

o conclude* in t!is experiment* P()D controller can "e tuned "y using +iegler ,ic!ols Close-oop et!od !e met!od de$eloped t!eir turning rules "y stimulating a great num"er o% di%%erent processes and correlating t!e controller parameters &it! %eatures o% t!e step response Basically* close-loop more accurate t!an open Iloop in terms o% less sensiti$e to noise and distur"ance and steady state error and transient response can "e controlled easily in close-loop system "y simple ad#ustment o% ampli%ication in loop !e experiment t!at &as conducted is only single capacity process "ased on t!e result on t!e c!art &!ere o$ers!ooting at single capacity process &as lo&er t!an and "ecame increasing starting %rom %irst %irst trial until t!ird trial compared












P a g e | 1/

ma'e sure t!e result or c!art is recorded su"se;uently t!e data is set up in monitor so t!at t!e output response in t!e c!art &ill sta"le !e num"er o% trial* P()D $alues and t!e set point must "e mar'ed on t!e c!art paper properly so t!at &e &ill not con%used &!ene$er t!e $alues are c!anged astly* t!e output response o% t!e c!art must "e o"ser$ed properly &!et!er t!e response is oscillatory or not &!ere i% t!e response is oscillatory* t!e PB1 must "e increased "y 5 to o"tain sta"le response and lo& $alue o% control gain $alues 2
ADDITIONA' ;UESTIONS










P a g e | 1H

in single capacity and t&o capacity processes using P)D controller and to tune t!e P)D controller using +iegler ,ic!ols closed-loop met!od

?e%erences 1 otal6 otal6aal$eAolution l$eAolutionss 27014* Uuly 14 Introduction 14 Introduction to to Valve Valve and Actuators Actuators ?etrie$ed %rom !ttps:@@&&&youtu"ecom@&atc!T$.tiyLFgAa-s 7 Technology Transfer  27014* 8e"ruary 75 ?etrie$ed cto"er 74* 701* %rom Process

CPB30004 Process Dynamics and Control Experiment 4: Gas pressure process control lab report

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