Investigation of Inlet Gas Streams Effect on the Modified Claus Reaction Furnace

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1 Advances n Chemcal Engneerng and Scence, 03, 3, 6- Publshed Onlne August 03 ( Investgaton of Inlet Gas Streams Effect on the Modfed Claus Reacton Furnace Reza Rezazadeh, Sma Rezvantalab * Shahd Hashemnejad Gas Processng Company (S.G.P.C), Khangran, Iran Department of Chemcal Engneerng, Urma Unversty of Technology, Urma, Iran Emal: * sma_rezvan@yahoo.com Receved May 30, 03; revsed June 30, 03; accepted July 30, 03 Copyrght 03 Reza Rezazadeh, Sma Rezvantalab. Ths s an open access artcle dstrbuted under the Creatve Commons Attrbuton Lcense, whch permts unrestrcted use, dstrbuton, and reproducton n any medum, provded the orgnal work s properly cted. ABSTRACT The objectve of ths paper s to model the man reactons that take place n the Claus reactor furnace and compare t wth actual data and smulated process. Snce the most mportant pont s the selecton of sutable reacton condtons to ncrease the reactor performance, the model s formulated to predct the performance of the Claus plant. To substantate the theoretcal model, we used actual process condton and feed composton n Shahd Hashemnejad Gas Refnery. Model equatons have been solved by usng MATLAB program. Results from MATLAB are compared wth those from SULSIM smulator and wth actual plant data. The AAD (Average Absolute Devaton) of modelng results wth actual data s.07% and AAD of smulaton results wth real data s.77%. Error values are very lttle and show accuracy and precson of modelng and smulaton. The predctng curve for dfferent parameters of the reactor furnace accordng to varable condtons and specfcatons are gven. Keywords: Claus Process; Hydrogen Sulfde; Modelng; Reactor Furnace. Introducton Hydrogen sulfde (H S) s produced from sulfur compounds n fossl fuels such as natural gas or ol. Sour gases (H S and CO ), are removed from the natural gas or refnery gas by means of one of the gas treatng processes. Due to global envronmental rules, refneres have to recover sulfur from nature. H S contanng acd gas stream s flared, ncnerated, or fed to a sulfur recovery unt. The Claus process s commonly used to reduce the emsson of sulfur compounds nto the atmosphere. Recently recovery of sulfur s done by means of the modfed Claus tal gas clean-up processes. In these processes, H S over a catalyst converts to elemental sulfur where the reacton takes place n a hgh temperature furnace. The recovery process s the reacton between H S and ar to form sufur and water. Followng reacton s the man reacton n the recovery process: KJ O Sx HO heat () x Kgmole In the orgnal Claus process, control of ths reacton was dffcult and sulfur recovery effcences were low. * Correspondng author. In order to overcome these dffcultes and also ncrease the effcency of the process, several modfcatons of the Claus process have been developed. In modfed process, free flame total oxdaton of /3 of the H S to SO followed by a reacton over the catalyst of SO wth the remanng /3 H S. Accordng to Mohamed Sass and Ashwan K. Gupta modfed Claus process for a Sulfur Recovery Plant conssts of several stages []: ) Combuston (In the Reactor Furnace) Hgh T 3O SO HO heat 8000 KJ Kgmole Hgh T SO3 S HO (3) HR 7000 KJ Kgmole ) Redox (Catalytc Converter) These are smplfed reactons whch actually take place n a Claus unt. There are varous speces of gaseous sulfur S, S 3, S, S, S 6, S 7, and S 8. Equlbrum concentratons of these sulfur compounds are not known n the Catalytc, Low T 3 SO Sx HO heat X () 08 KJ Kgmole () Copyrght 03 ScRes.

2 R. REZAZADEH, S. REZVANTALAB 7 Overall O Sx 3HO heat X KJ Kgmole entre of process. Addtonally, gas stream contans water saturated wth - 80 mol% H S, mol% hydrocarbons, and CO whch can result n carbonyl sulfde (COS) carbon dsulfde (CS ), carbon monoxde (CO), and hydrogen []. Most Claus plants operate n the multstep process straght-through mode as shown n Fgure. The combuston s carred out n a reducng atmosphere wth only enough ar ) to oxdze one-thrd of the H S to SO, ) to burn hydrocarbons and mercaptans, and 3) for many refnery Claus unts, to oxdze ammona and cyandes. The process ncludes the followng operatons: Combuston: burn hydrocarbons and other combustbles and oxdze one-thrd of the H S to provde necessary SO to react wth remander H S for producng S n the furnace. Waste Heat Recovery: Cool combuston products. Sulfur Condensng: Cool outlet streams from waste heat recovery unt and from catalytc converters. Reheatng: Reheat process stream, after sulfur condensaton and separaton, to a temperature hgh enough to reman suffcently above the sulfur dew pont. In order to nvestgate dfferent aspects of the modfed Claus process, a number of studes have been performed on man burner and sulfur recovery n ths process. Monnery et al. modeled the modfed Claus process [3]. Kelly Anne Hawboldt has studed mathematcal modelng of reactons n the process []. Recently, S. Asad et () al. used TSWEET smulator to optmze the recovery of sulfur []. At frst approach, we have used a mathematcal model for the key reactons that take place n the reactor furnace. In the second approach, we have smulated the process wth a commercal smulator. Fnally usng the model and smulaton, we have compared obtaned results and proposed some mprovements on the base case.. Knetc Studes Claus process has been nvestgated va dfferent aspects, expermental and theoretcal perspectves. Paskal et al. gves a summary of the man reactons thought to occur wthn the Claus furnace [6,7]. Clark et al. dscussed the mechansms behnd the formaton of key sulfur contanng speces found wthn the furnace, and n a subsequent study outlne prmary reacton pathways for the prncpal components n the furnace [8,9]. Whle there have been numerous attempts to model the Claus process based on smplfed knetc expressons, the complexty of the chemstry and the number of nvolved reactons has precluded the accurate predcton of outlet compostons. As t mentoned before, gas stream contans dfferent compounds such as H S, CO and hydrocarbons. Most mportant compound s H S and several groups have studed t s decomposton under dfferent condton. As result, t suggested that there are numerous reactons on the catalytc decomposton of H S n the clause process. Accordng to the studes, gaseous H S exsts n chemcal equlbrum wth elemental hydrogen and sulfur by the followng equaton: Fgure. Three-stage straght-through sulfur plant. Copyrght 03 ScRes.

3 8 R. REZAZADEH, S. REZVANTALAB (6) x H S x Oxdaton ncludes two staged reacton, frst oxdaton of H S and followed by reacton between H S and SO that lmtng stage of the Claus reacton s the second part [0]. 3 O HO SO (7) H S SO H O S (8) Durng the reacton n the furnace and accordng to the exstence of ammona n the gas stream, oxdaton of NH 3 wll take place. Recently, Clark has mentoned that under 00 C ammona oxdaton s neglgble. Addtonally, he noted n compettve oxdaton, frst of all H S, and then methane, fnally NH 3 react. On the other hand, Goar et al. found rate of hydrocarbon combuston s more than ammona and NH 3 s more than H S []. Formaton of COS and CS n the Claus reacton furnace are also very mportant n the modelng. Feld studes have revealed that concentratons of COS and CS at the ext of the reacton furnace/ waste heat boler typcally le between 00 ppm and mol% []. However, these seemngly small concentratons n the furnace product stream can represent nearly half the sulfur emssons from a tal gas clean-up unt [3]. It s possble to hydrolyze COS and CS back nto H S n the Claus catalytc converters accordng to the followng stochometry: COS H O CO H S (9) CS HO CO (0) As t mentoned, there many reactons whch may take place n the furnace accordng to the condtons such as temperature and pressure. Full lst of reactons that occur n the furnace s not obvous and for the known reactons, reacton rate expressons are not avalable. In current work we assumed that gas stream conssts of CH, CO, H S, H O, O, N, CO, CS, COS, S, SO, H. Regardng gas stream composton, mportant reactons whch take place n furnace and we use n the modelng are lsted below. 3O SO HO () SO 3 S HO () CH O CO HO (3) CO CO O () S H () CH S CS (6) CO S COS (7) 3. Mathematcal Model The basc structure of the model consst of the equatons of mole and energy conservatve rule the furnace, whch are related to each other and are functon of molar converson of H S n equlbrum reacton and temperature. In order to model the reactor, a steady-state smulaton has been used for mole and energy balance. Sames and Paskal presented emprcal correlatons to predct the fracton of CO, H, COS, CS and sulfur (as S) n the effluent of the Claus furnace. The correlatons are obtaned from more than 300 tests on 00 dfferent sulfur trans; wth dfferent flow confguratons processng acd gas feed streams []. These emprcal correlatons are presented n Appendx. We use these equatons to model the furnace and mole balance. In ths work, furnace pressure s 30 kpa (absolute) and pressure drop (ΔP) s 0 kpa. Usng emprcal equatons and applyng n the mole balance for the compounds, we get the mole balance equatons, for each compound. For gas components n the outlet gas stream: H S: RH f X f R CS f f f 3 CH H O: H O CH H S (8) f R CS f f X (9) 3 CH CO f f R CS CO CH CO : (0) - R COS R CO f f CO: RCO fch fco () SO : f X 3 () CH : 0 (3) O : RCOSRCO f CH f CO () N : 79 f f CH R CS () S : 3 XRCOS f f f CH CO RCS f CH RH (6) R H f (7) H : CS : RCS f (8) CH COS: RCOS fch fco (9) Copyrght 03 ScRes.

4 R. REZAZADEH, S. REZVANTALAB 9 Total moles: f CH 3 R CS R CO fco R CS R CO f RH fn fho X 3 (30) X: Flow rate of H S converson at the equlbrum Claus reacton At equlbrum: K p HO S SO 3 3 total mols (3) By nterpolaton n the K p curve vs. furnace temperature (GPSA), we calculate: 0. p K 0.60T 0.9T C, K Kpa (3) p Replacng molar flows n Equaton (8) through 30 n Equaton (3) resulted nto a new equaton, functon of temperature, n the followng form (see below): where the A, B, C, D are functon of feed composton and would be calculated numercally. In order to calculate the reactons enthalpy, we used equaton 3 and data provded n Table. Table represents standard enthalpy of formaton and heat capacty parameters for each component. 7 SUM H rxn H Converson rxn f rx n (3) H rxn s standard enthalpy of reactons n C, f rxn() s molar flow rate of lmtng compound n each reacton, Converson s converson value of lmtng compound n each reacton. Replacng all mentoned equatons resulted nto a new Equaton (3) n whch converson of H S s functon of temperature of reacton furnace (Table ). A ATBT CT DT X B AT BT C T DT (3) A 0, A, A, B 0, B, B, C, C, D, D are constant paramenlet gas stream condton. ters that would calculated numercally accordng to the In order to establsh a reference pont, calculatons are carred out for a base case and the operatng condtons used are gven n Table 3. Our base case s Shahd Hashemnejad Gas Refnery. Shahd Hashemnejad (Khangran) gas refnery s n Sarakhs, Khorasan provnce. Operatng condtons s composton of nlet gas stream to the Claus process n the refnery. Next step, applcaton of the feed gas condton n the equatons resulted nto the parameters of mole and energy balance equatons. Calculated parameters are presented n Table.. Process Smulaton In order to compare the mplcatons of the reacton fur- Table. Compound heat capacty parameters and H 98 kj/kg mole. 0 H,98 a b c d at C kj/kgmole CH CO H S H O O N SO S CO CS COS H Table. lmtng spece and calculated ΔH rxn []. Lmtng spece Reactons ΔH (Kj/kgmole) CO H S CH H S H S CH CO CO CO + / O H S + 3/O SO + H O CH + O CO + H O H S + SO 3/S + H O H S /S + H CH + S CS + CO + /S COS rxn Table 3. Refnery claus process nlet gas condton. Feed Temperature 3 K ( C) Inlet ar temperature (average n summer and wnter) 30 K (77 C) Furnace pressure 30 kpa A Feed molar rate 68.9 Kgmole/h C H mole fracton 0.00 CO mole fracton 0.63 H S mole fracton H O mole fracton A X B 0.7X π T K (33) 0. C X 3f 0.XD0. Copyrght 03 ScRes.

5 0 R. REZAZADEH, S. REZVANTALAB - 0 Table. Calculated parameters for case study. A B C D nace model on desgn, ove rall sulfur recovery and emssons, ths modfed Claus plant was smulated usng SULSIM. SULSIM s program for Sulfur Plant Smulaton and represents smulaton package for SRU and TGTU desgn. Ths software has wdely accepted thermodynamc data and proprety thermodynamc propertes for all of the gas components and sulfur speces found n sulfur recovery processes. Fgure shows the flow dagram of the smulated Claus unt of Shahd Hashemnejad Gas Refnery.. Results and Dscusson As descrbed prevously, we mplemented real data from gas refnery n the model. In ths secton to verfy the model, we compare the output result from reacton furthree set of results. nace, model values and smulaton results. Table lsted It s obvous that furnace temperature obtaned usng model (098 K) s lower than actual temperature of reacton furnace (3 K), as the C temperature dfference s neglgble and t results nto.3% error. Smulated results shows that predcted temperature usng SULSIM software s K and hgher than Claus furnace temperature. Error occurred usng software s lower (0.7%). In ths case smulaton s more relable. Addtonally, sulfur converson obtaned from model results (6.63%) s n good agreement wth converson of sulfur n Claus plant (%) n gas refnery. On the other hand, results 0 7 from smulaton ndcate that sulfur converson s 60.8%. Accordng to the fact that obtaned conversons from model are attaned n lower temperature n comparng wth the plant temperature whle sulfur product s hgher, we can conclude that model s more effcent n sulfur converson. It s obvous that presented model n these condtons, s effectve even more than smulated process. As t s presented n the Table, n the furnace effluent there s sulfur vapor. It s due to the hgh temperature n the furnace; ths hgh temperature converts sulfur to S vapor. Accordng to Table, nlet ar rato to acd gas feed n Claus plant s 0.86 and n our model ths rato s As we used ths obtaned rato n our smulaton, smulaton and modelng resulted n the same rato. Therefore modelng and smulaton errors are low and about 3.%. Snce sulfur producton s hgh n comparng wth actual plant; ar consumpton s low, CO concentraton dfference s about 0.0 (mole %), t means error s 0.3%; we can conclude that n all cases, smulated and modelng are more effcent. Predcted N concentraton usng equlbrum model s (mole %) whereas N content n the plant outlet gas stream s 39 (mole %). Snce In emprcal equatons of model, t s assumed ar consumpton s low, results are logc and dfference between real state and model results s acceptable. Snce ar consumpton s low, ts acd gas capacty s more than actual plant and can predct better results. Smulaton has the same manner n the predcton of N concentraton. H O concentraton n the outlet stream from model s less than plant outlet water content. The model performance was not good n water case and error value s about 7.8%. Whle H O content n smulaton s closer to the actual data and lower error has occurred. Smulaton performance s better n ths case. O component n Claus plant damages the equpments (catalyst exchanger) and must be mnmzed, n Claus plants O content s zero. Predcted concentraton s Fgure. SULSIM smulaton used for gas for Khangran gas refnery (S.G.P.C). Copyrght 03 ScRes.

6 R. REZAZADEH, S. REZVANTALAB Table. Comparson of plant value and results from model and smulaton for S.G. P.C. Condton of Outlet Stream Actual values for outlet concentraton from W.H.B n Claus un t Predcted Values usng Model Predcted Values usng SULSIM smulaton T (furnace temp) 3 K ( 80 C) 098 K (8 C) K ( 88 C) F out (kgmole/hr) X (mole%) CH X CO X X HO X O (mole%) 3 3.0% % (mole%).9%.0%.9% (mole%) 0.% 8.9% 9.% (mole%) 0% 0.0% 0 X (mole%) N 39% % % X SO (mole%).8%.63%.30% X (mole%) %.39%.6% S X (mole%) CO 0.% 0. 3% 0.737% X (mole%) COS,CS 0.9% X (mole%) 0.%.03% H Rato (ar/feed) 0.86 S ulfur converson %.63% 0.0% 0.08% % % 0.0% and error value s acceptable. The model pre- CH concentraton w ould drop to zero n the outlet of furnace. Checkng the actual outlet concentraton t s dcted obvous that there s no methane n outlet stream, there- fore no error has oc curred n pre dctng of methane con- centraton. Table represents actual data for the concen- traton of CS and COS are greater than equlbrum model, data obtaned from sm ulaton. As you know, producton of CS and COS n the Claus furnace reduces the effcency of total pla nt and t s better to decrease these components. Therefore sm ulaton and model out- puts are more effectve. Accordng to Sames (990), COS forms n WHB exch anger, therefore dfferenc e between predcted concentraton and plant data verfes the for- mato n reacton of COS []. Ths take p lace n W.H.B as followng equaton: CO S COS (0) Predcted S content n both methods s greater than plant data. There s a bg dfference between real and predcted values for S ; t s due to the formaton of lqud sulfur n WHB. Accordng to Table and comparson between results and plant data, and also neglectng the error n CO and H predcted concentratons, average error s about 3.% and.36% for model and SULSIM smulaton; also AAD (Average Absolute Devaton) n comparng actual data wth modelng and smulaton results are.07% and.9%, respectvely. We can conclude that our model s more effcent and applcable for other Claus plants wth dfferent nlet composton... H S Concentraton Effects Fgure 3 shows reacton furnace predcted temperature vs. nlet H S content usng model and smulaton. Both smulaton and model have smlar trend. Accordng to the fgure, model predcts that % ncrease n H S content wll result nto 7. C ncrease n furnace temperature. In order to combust hydrocarbons and aromatcs, furnace temperature must be 00 C. Accordng to the model, f nlet gas stream contans more than 6% H S n current plant, temperature would ncrease to hgher than 00 C (33 K). Fgures (a) and (b) llustrate the predctons of model and smulaton for H S and sulfur converson n furnace vs. ncrease n H S content n feed. As model predcts, for one percent of the mole fracton of H S n feed stream, sulfur converson ncreases by 0.% n reacton furnace and S mole fracton n outlet gas stream ncreases 0.%. Smulaton has smlar manner n ths case. Obtaned results both are matched. It should be noted that sulfur converson n Fgure (b) shows model and smulaton have smlar trend. Therefore there s a neglgble dfference between the model and smulaton predcton n 8% H S n Fgure (a). It s due to errors occurred n the smulaton. Fgure shows the effect of concentraton n feed stream on the effluent H S content. As H S content ncrease n the feed, model predcts a trend for H S content n outlet whch decreases and then wth a lower slope ncreases and fnally decreases. The results ndcate that n lower concentratons, furnace temperature s low and ncrease n the H S (to 30%) content would ncrease the slope of H S converson lne that results to decrease n H S content n the outlet stream of furnace. In the hgher concentratons, snce furnace temperature s more than prevous, H S crackng and converson n Claus reacton ncreases and unconverted hydrogen sulfde Fgure 3. Smulaton and model estmaton for Modfed Claus plant reacton furnace temperature vs. H S content. Copyrght 03 ScRes.

7 R. REZAZADEH, S. REZVANTALAB (a).. Effect of Inlet Temperature In ths secton, temperature effects have been nvestgated. We can predct the effect of preheatng on the furnace temperature and converson n furnace. Fgure 6(a) shows the varaton of furnace temperature vs. nlet temperature of acd gas. Accordng to the fgure, furnace temperature ncreases. C by 0 C ncrease n nlet temperature. Therefore, f we can ncrease the desgn temperature ( C) to C, furnace reactons wll take place n 9 C. Fgure 6(b) shows the H S converson by ncrease n the temperature. As can be seen from Fgure 6, H S (b) Fgure. Comparson of predcted. (a) H S converson; (b) sulfur converson vs. H S mole fracton n feed stream. (a) Fgure. Estmaton for H S content n outlet stream vs. H S mole fracton n feed stream. n the outlet decreases. As can be seen n the fgure, the reducton of H S n the effluent s agreement wth ncrease n H S content n acd feed gas. For ths case, model predcton s more relable than smulaton. (b) Fgure 6. (a) Modfed Claus furnace temperature predcton for Khangran Gas refnery vs. nlet acd gas temperature; (b) H S and sulfur converson vs. nlet acd gas temperature. Copyrght 03 ScRes.

8 R. REZAZADEH, S. REZVANTALAB 3 converson ncreases by 0.6% when nlet temperature ncreases 0 C. Also ths fgure demonstrates that H S converson n furnace would ncreases from 7.66% to 7.7% n preheated feed ( C). Also 0 C ncrease n temperature of nlet ar results nto. C ncreases n furnace temperature, 0.03% ncrease n H S converson and 0.3% ncrease n sulfur converson. If both acd gas feed and nlet ar preheated separately and equally 0 C, reacton furnace temperature ncreases 7. C, H S converson 0.% and sulfur converson 0.3%. From a theoretcal pont of vew, there s an optmal temperature n the furnace reactor to get the more effcent performance, maxmzes sulfur producton and H S converson as reported n the prevous sectons for Claus process. A soluton for ths problem s fuel gas njecton to the furnace n order to ncrease the temperature. By one percent ncrease fuel content n the nlet gas, furnace temperature would ncrease 30 C - 0 C. Calculaton showed that 000 Sm 3 /hr fuel njectons n acd gas feed (0000 Sm 3 /hr) for Shahd Hashemnejad Refnery, furnace temperature would ncrease 30 C. More hydrocarbon content n the feed wll produces more CS and COS n the furnace. Increasng flow rate causes decrease n furnace capacty. It was observed the postve effect of fuel njecton by ncreasng the temperature, led to reducton n plant capacty. 6. Concluson The reactor furnace for an ndustral three-stage straghtthrough sulfur plant wth dentcal feed gas composton and operatng condtons was molded and compared. The results of the modelng and steady state smulaton have been presented n Table. The results showed that H S converson could be promoted by an ncrease n hydrogen sulfde content n the feed gas. Therefore f we could enhance the H S concentraton, sulfur converson and overall effcency of the furnace would mprove. Ths also could lead to decomposton of aromatc compounds such as BTEX, addtonally furnace temperature would ncrease. In order to ncrease furnace temperature, fuel njecton s possble but, t must be optmzed to prevent plant capacty reducton. On the other hand, reducton n CO and N nlet flow helps to reduce the volume of effluent and ncreases the furnace ca pacty n the Claus plant. Also results demonstrated that by utlzaton of heat nput (preheated feed and ar) n a furnace of a plant, the performance of the reactor would mprove. Envronmental Scences, Vol., No., 008, pp. 0-. do:0.38/ajessp [] K. Karan, An Expermental and Modelng Study of Homogeneous Gas Phase Reactons Occurrng n the Modfed Claus Process, Ph.D. Thess, Unversty of Calgary, Calgary, 998. [3] W. D. Monnery, et al., Modelng the Modfed Claus Process Reacton Furnace and the Implcatons on Plant Desgn and Recovery, The Canadan Journal of Chemcal Engneerng, Vol. 7, No., 993, pp do:0.00/cjce [] K. A. Hawboldt, Knetc Modelng of Key Reacton n the Modfed Claus Plant Front End Furnace, Thess, Unversty of Calgary, Calgary, 998. [] S. Asad, et al., Effect of H S Concentraton on the Reacton Furnace Temperature and Sulphur Recovery, Internatonal Journal of Appled Engneerng Research, Vol., No., 0, p. 96. [6] H. G. Paskall, Capablty of the Modfed-Claus Process: A Fnal Report to the Department of Energy and Natural Resources of the Provnce of Alberta, Western Research & Development, Cheyenne, 979. [7] H. G. Paskall, Reacton Furnace Chemstry and Operatonal Models, Sulphur Recovery, Western Research, Calgary, 98. [8] P. D. Clark, et al., Mechansm of CS Formaton n the Claus Front-End Reacton Furnace, Proceedngs of the 7th Annual Laurance Red Gas Condtonng Conference, Norman, - March 997, pp [9] P. D. Clark, et al., Mechansms of CO and COS Formaton n the Claus Furnace, Industral Engneerng and Chemstry Research, Vol. 0, No., 00, pp do:0.0/e99087l [0] P. A. Tesner, M. N. Nemrovsk and D. N. Motyl, Knetcs of the Thermal Decomposton of Hydrogen Sulphde at C, Knetcs and Catalyss, Vol. 3, 990, p. 3. [] B. Goar, et al. Sulfur Recovery Technology, Energy Progress, Vol. 6, No., 986, pp [] J. A. Sames and H. G. Paskall, Smulaton of Reacton Furnace Knetcs for Splt-Flow Sulphur Plants, Sulphur Recovery, Western Research, Calgary, 990. [3] E. A. Lunstra and P. E. Haene, Catalyst Added to Claus Furnace Reduces Sulfur Losses, Hydrocarbon Process, Vol. 68, No. 7, 989, pp [] J. A. Sames, et al., Evaluaton of Reacton Furnace Varables n Modfed Claus Plants, Sulphur Recovery, Western Research, Calgary, 990. REFERENCES [] M. Sass and A. K. Gupta, Sulfur Recovery from Acd Gas Usng the Claus Process and Hgh Temperature Ar Combuston (HTAC) Technology, Amercan Journal of Copyrght 03 ScRes.

9 R. REZAZADEH, S. REZVANTALAB Appendx The Western Research (Sames and Paskall) correlatons are gven below: R(CO)= 0.00A 0.03 exp (.3 A) R(H ) = fracton of furnace nlet H S that cracks to H and S R(H ) = 0.06 (±0.0) R(COS) = fracton of furnace nlet carbon that forms COS R(COS) = 0.0 tangent (00A) for 0 A 0.86 R(COS) = 0.3 for A > 0.86 R(CS ) = fracton of furnace nlet hydrocarbon that forms CS R(CS ) =.6 A 0.97 exp( 0.96 A) R(S) = fracton of furnace nlet H S that forms elemental S R(S) =.8A.099 exp ( 0.73A) where A = mole fracton of H S n the acd gas feed on a dry bass. Nomenclature f : Molar flow rate of th compound X: Mole fracton of compound R(): fracton of furnace nlet of th compound K p : Equlbrum constant T: temperature π: furnace total pressure C p, : Heap capacty of th compound ΔH rxn : Reacton enthalpy H,98 0 : Standard enthalpy of th compound formaton W.H.B: Waste Heat Boler Copyrght 03 ScRes.