tail gas

APPLICATION REPORT

Tail gas treatment

Burner / line heater 

Reactor 

Heat recovery

300 °C

Quench column

Absorber 

40 °C

To incinerator

Stripper 

To Claus unit

6. Lean amine

1. Combustion air 

2. Fuel gas

3. Reducing gas (H2/CO) (optional)

H2S

4. Claus tail gas (S, COS, CS2)

Quench recycle 5. Rich amine

Reboiler 

Sour water  Purge to another  absorber 

Process overview Gases from varous reery processg operatos cota hydroge suphde ad occasoay carbo doxde. Some H2S  reery gases s formed as a resut of coverso of suphur compouds  processes such as hydrotreatg, crackg ad cokg. Evrometa ad ppee reguatos requre that most of the H2S must be removed from pat ta gas ad coverted to eemeta suphur. Ta gas treatmet processes are used extesvey to cea up Caus suphur recovery ta gas streams to meet evrometa requremets where overa suphur recovery must exceed 95 – 97 percet. The resdua suphur recovered from the ta gas stream s recyced as H2S back to the Caus suphur recovery, resutg  tota suphur recovery efcecy of over 99.9 percet.

The Caus ta gas feed s heated to about 300 °C usg a e burer wth optoay added H2 or  a mxture of H2/CO. The heated gas the ows through a catayst bed where suphur compoets SO2, S, COS ad CS2 are coverted to H2S. The gas s cooed to 40 °C  a optoa heat recovery system ad water-quech tower. The H2S s set to a ame ut where H2S s seectvey removed  a ow pressure ame absorber, typcay 10 to 400 ppm. The acd gas from the sovet regeerator s recyced to the suphur pat for suphur  recovery. The absorber offgas s thermay or  cataytcay cerated. The most commo TGCU processes are the She Caus Offgas Treatg / Beavo Suphur Reducto-MDEA uts capabe of  achevg overa recoveres of 99.9 percet. 2  7  2  1   /    0   3   /    0  2  •   3   /   2   0   0   9 

2721/03/02

TAil GAS TREATMEnT

Tail gas treatment challenges

Metso solutions

Proper catayst performace s requred  order  to keep the aowed SO2 eves reeased to the atmosphere. if the catayst oses actvty, there s a dager of SO2 breakthrough. Ths ca cause corroso  the crcuatg quech water crcut, ad the SO2 posos the ame. Catayst actvty ad pH eves of the crcuatg water are usuay carefuy motored. Ame souto mateace s requred ad typcay there s a ame ter upstream of  the regeerator. Correct vave seecto for cotro ad soato s therefore a crtca factor  overa TGTU performace.

We have severa cotro, o-off ad ESD staatos wordwde  suphur recovery pats ad over  20 years of experece  the vave requremets for these pats. Suphur compouds beg very hoste to metas, partcuary at hgh pressures ad temperatures ecoutered  reg, the quaty of  cotro vaves takes o prme mportace.

Health, Safety, Environment – Vave eakg poses both a evrometa ad safety ssue due to rsk of re ad toxcty of voate gases. ESD ad o/off vaves must be abe to perform ther acto  a process or equpmet faure. Top-class products at maximum yield – The market cas for cea products ad hgh quaty. it s mportat that the process s stabe, exbe ad uder cotro. Poor cotro vave performace reduces the accuracy of throughput cotro ad adversey affects to the pat performace ad aso the dowstream processes. Maintenance costs - Suphur crystazato poses as rsk of vave cog up. Poory performg vaves  the process must be servced because they w have a drect mpact o the efcecy of the process. The cost of uschedued mateace w be qute hgh, up to 70% of the cost of a ew vave  some appcatos. Add ths to the cost of removg the vave from the e ad dsrupto of the process ad the tota cost w be much hgher. Plant run-time – Reeres are ookg for oger  pat ru-tmes sce dowtme meas producto osses ad s a remarkabe cost cudg mateace costs. Ths requres reabe equpmet ad process cotro.

2

APPliCATiOn REPORT 3/09

Health, Safety & Environment - Rotary stem operato reduces fugtve emssos ad protects from eakg. Packg costructo meets the atest emsso stadards. Our products are re tested ad appy to the atest stadards. nees VavGuardTM parta strokg w esure that pat emergecy shutdow vaves w aways perform propery whe eeded. Efficiency - Throughput osses due to stckg ad poor cotro performace w be avoded wth hgh performace rotary vaves. Fow through the process ut may be chaged as the eed arses wth rageabty of 150:1 ad further wth fu bore ba vaves. Our advaced nD9000® dgta vave cotroer esures hgher postog accuracy ad faster respose to reduce process varabty. Correct vave seecto ad szg wth our neprofprogram we ca assure the best vave performace ad process cotro. Availability - Smpe rotary desgs, same face-to-face dmesos, ad goba servce etwork ad vetory maagemet w hep you to optmze your mateace actvtes. Rotary vaves have bee  servce for  severa years wthout requrg mateace ad show o sg of eakage. To protect the vaves from suphur  bud-up they ca be equpped wth steam jacketed bodes ad hgh temperature bearg seas. Reliability - Tred data coected by our smart vave cotroers ad aaysed by FedCare cogurato ad codto motorg software based o ope FDT/DTM techoogy makes t possbe to predct ad respod to mateace requremets ad reduce uschedued dowtme. Ths gves fu traspar ecy to the vave performace  process cotro.

TAil GAS TREATMEnT

2721/03/02

Burner/reactor applications

Amine applications

1. Combustion air  2. Fuel gas 3. Reducing gas (H2 /CO) (optional) 4. Claus tail gas (S, COS, CS2) Challenge – The ma cotro parameters to cotro  the cataytc process are typcay et temperature, hydroge cotet ad ar/fue rato  the -e burer. The et temperature s usuay mataed at the owest temperature that w acheve the desre coversos, typcay as ow as 275 °C. The reacto temperature may be requred to crease as the actvty of the catayst deces. Burer cotro s esseta  order to avod premature catayst faure. if A/F rato s too hgh, oxyge ca bypass the burer ad degrade the catayst. At too ow A/F rato, soot w form that w pug the catayst pores, reducg t’s actvty ad wth greater amout w evetuay pug the catayst bed, shuttg dow the etre ut due to pressure drop crease. Fugtve emsso cotro s mpor tat for acd gas servce ad  may cases nACE s apped.

5. Rich amine 6. Lean amine The cooed efuet s cotacted  the absorber wth seectve performace sovet to absorb most of  the H2S. icerato of the treated off-gas from the absorber esures that a suphur speces are coverted to SO2 pror to vetg. The H2S-rch ame from the absorber s preheated  a reboer before strppg the absorbed acd gases from the souto. The ea sovet s recyced to the absorber after  coog. MDEA, a tertary ame, has become the most commo seectve sovet due ts resstace to degradato ad ow tedecy to corroso.

Metso solution – Fetro eccetrc pug vave for  accurate ad hgh rageabty appcatos. nedsc buttery vave s aother opto partcuary for  arge sze appcatos. Benefits – log astg meta seat tghtess wth re safe costructo assures process avaabty. Optmum ow characterstcs wth dyamc perfor mace ad cotro oop stabty provde accurate cotro eve at ow opeg ages. Ths s extremey mportat  suppyg stabe ow to the burers. The savgs are reazed  reabe burer  cotro. Process reabty ca be mproved further  by nD9000 o-e dagostcs that provdes fu trasparecy to vave performace durg process ru. Rotary desg ow emsso wth reabe stem packg provdes smpe ad cost effectve way to reduce overa fugtve emsso.

Challenge – Key operatoa parameters of a TGTU cude cotro of SO2 breakthrough from the reactor  ad the ea ame temperature. Due to creasg ame costs, oss reducto s desrabe. A breakthrough of SO2 w cause corroso  dowstream equpmet ad severy cotamate the ame souto. it may be ecessary to recam or dscard the ame foowg a arge breakthrough of SO2. Ths ca be cotroed by excess hydroge  the cataytc reactor. The desg ad cotro of the upstream quech tower s very mportat because t determes the gas temperature eterg the absorber. Depedg o the type of sovet used the ea ame temperature shoud typcay ot exceed 38 °C  order to meet the off gas H2S speccatos. Metso solution – Fetro eccetrc pug vave for  accurate ad hgh rageabty appcatos. nedsc buttery vave s aother opto partcuary for  arge sze appcatos. Benefits – log astg meta seat tghtess wth re safe costructo assures process avaabty. Optmum ow characterstcs wth dyamc per formace ad cotro oop stabty provde accurate cotro eve at ow opeg ages. Ths s extremey mportat  provdg stabe rch/ea ame oadgs. The savgs are reazed  reduced ame costs due to reduced varabty. Process reabty ca be mproved further by nD9000 o-e dagostcs that provdes fu trasparecy to vave performace durg process ru.

Neldisc  Finetrol  APPliCATiOn REPORT 3/09

3

APPLICATION REPORT

Optimize your amine plant performance, reduce energy and maintenance costs and produce top-class products with our intelligent rotary control, on-off and ESD-valves.

Neles intelligent valve controllers

Visibility to switching  applications

The formato provded  ths buet s advsory  ature, ad s teded as a gudee oy. For specc crcumstaces ad more detaed formato, pease cosut wth your oca automato expert at Metso.

Metso Automation Inc. Europe, Levytie 6, P.O. Box 310, 00811 Helsinki, Finland. Tel. +358 20 483 150. Fax +358 20 483 151 North America, 44 Bowditch Drive, P.O. Box 8044, Shrewsbury, MA 01545, USA. Tel. +1 508 852 0200. Fax +1 508 852 8172 South America, Av. Independéncia, 2500- Iporanga, 18087-101, Sorocaba-São Paulo Brazil. Tel. +55 15 2102 9700. Fax +55 15 2102 9748/49 Asia Pacific, 238A Thomson Road, #25-09 Novena Square Tower A, 307684 S ingapore. Tel. +65 6511 1011. Fax +65 6250 0830 China, 19/F, the Exchange Beijing, No. 118, Jianguo Lu Yi, Chaoyang Dist, 100022 Beijing, China. Tel. +86-10-6566-6600. Fax +86-10-6566-2575 Middle East, Roundabout 8, Unit AB-07, P.O. Box 17175, Jebel Ali Freezone, Dubai, United Arab Emirates. Tel. +971 4 883 6974. Fax +971 4 883 6836

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