Title of Invention	"IMPROVED CONFIGURATION AND PROCESS FOR SHIFT CONVERSION"
Abstract	Overall steam demand for hydrogen production in shift reactor is lowered by splitting the syngas feed stream (101) into first portion (102') and second portion (102"). The first portion (102') is fed to a first shift reactor (110) to form a first product (112). The first product (112) is combined with the second portion (102") of the syngas feed prior to entering a second shift reactor (120).

Full Text

Field of The Invention The field of the invention is hydrogen production, and especially hydrogen production from synthesis gas relates with reduced steam consumption while maintaining predetermined design values for hydrogen to carbon monoxide ratio. Background of the Invention Numerous processes are known in the art to produce hydrogen from various materials, including steam reforming of natural gas, syngas, or naphtha, catalytic reforming of heavy straight run gasoline or heavy oils (e.g., fuel oil), and partial oxidation of heavy oils or natural gas. Steam reforming of hydrocarbonaceous material is particularly advantageous due to the relatively simple configuration and relatively robust operation. However, generation of steam for the reforming process required often relatively largo quantities of energy, To reduce the energy demand for steam production, steam may be internally provided by quenching hot gas from the reformer in direct contact with water as described in U.S. Pat. No. 3,545,926 to Schlinger et al., or U.S. Pat. No. 5,152,975 to Pong. Such configuration may provide a significant reduction in energy consumption for steam production. However, depending on the particular operating conditions, it may be necessary to heat the quenched gas prior to entry into the shift converter, which reduces the energy savings to at least some degree. Alternatively, the reforming process may be split into two sections in which the feed gas is reformed with steam in the first section and with oxygen in the second section as described in U.S. Pat. Nos. 4,782,096 and 4,999,133 to Banquy. While such configurations generally require less overall steam as compared to n conventional steam reforming processes, several disadvantages nevertheless remain. Among other things, operation of the second section generally requires an oxygen rich gas (typically comprising 80 vol % or even more oxygen), which has to be generated in an air separation or other oxygen enrichment equipment. Thcrcfore, wiiilc various conflgurations and mcthods for steam-based production of hydrogcn-containing gases are known in the art, all or almost all of them suffer from onc or uioro tlimulvanlngcfl. Coniioquonlly, tliere In ndll n nccd to pi'ovldo impiovcd coiiligumtloiiii and rnclhods to reduce cncrgy costs associatcd with steam consumption in various hydrogen production plants, and especially in steam shifling/reforming, parţial oxidation, or gasification plants. Bricf Pcscription of The Prawtng Figurc l is a schematic of an cxcmplary configuration for hydrogen production from synthcsis gas according to the inventive subjcct matter. Figuro 2 is a prior art schematic of a known configuration for hydrogen production from synlhesis gas. Figurc 3 is n tablo indicating composition, flow rate, and tcmpcrature of various streams of the configuration of Figurc 1. Figuro Figure 5 is a schematic of another cKcmplnry configuration for hydrogcn production from synthcsis gas according to the inventive subject matter. Figuro 6 ir. a tablo indicating oxcrnplnry opcrating conditions of the configurotion of Figure 5. Figutes 7A-7D are tables indicating material balances for first and second stages of cases l and 2 of Figure 6. Smmmu'Y of the InvcnUon Th« preicnt Invuntltw IM tllieelBU \ IVpm n fppd p» in wlilcii HIP deniond For «IPBIÎI or liumWIflfinilnn i» fllşnlflcdnilv redwcefl Işy splittinp thB feed gns fţuch thnt ono porlion is foci into n first shifl reactor and another portion is combined with the first shift reactor cfflucnt bcforc entcring a second shift reactor. In onc aspect of tlic inventive subject matter, a plant includes a first shifi reactor and a sccond shift renctor, whoicin tho first shift reactor rocoivcs a first portion of syngas from a gasification unit or parţial oxidation unit to fonn a first shift reactor cfftuent, and whcrein the sccond shift renctor rcccives a comblnnlion oftho first shift reactor e (fluent nnd a second porlion oftho syngns to fonn n sccond shift reactor offluont, In ospocinlly eontomplulcd |)lnntR, llio eocoiid portion oftho syngns is combinod with the first shift reactor effluent in an amount effective to reduce steam demand by at least 10%, more rypically at least 35%, and even more typically at least 45%, Altematively, where the wnlcr is provided to the syngas via humidification of the syngas, it is preferred that the second portion of the syngas is combined with the first shift reactor effluent in an amount effective to reduce water and/or energy consumption of the humidifier by at least 10%, more typically at Icnst 20%, nnd even more typically by at least 35%. Thercfore, espccially preferred second portions of the syngas will be between 50 vol% to 75 voP/o of mc total syngas. It is still furthcr conternplntcd (hat a prefcrred syngas includea carbon rnonoxide and hydrogon ni n molar rntio of nt Icmtt 2:1, nnd thnt yot nnothor portion of the syngns rnay bc bypnssed around the first and second shift reaclors for combination with the sccond shift reactor effluent. Furthcrmore, suitable plarits may also include an acid gas removal unit that is coupled to the second shift reactor to remove carbon dioxide from the second shift reactor cfilucnt. Therefove, a particularly preferred method of operating a plant will include one step in which a first shift reactor and a sccond shift reactor are provided. In another step, a syngas stream from a gnsificntion unit or a parţial oxidation unit is split into a first portion and a second portion, wherein the first portion is fed to the finst shift reactor to fonn a first shift renctor effluent. In a furthcr step, the first shift reactor effluent is combined with the second portion to fonn n inixecl feed gas, and in yet another step, the mixed feed gas is reacted in the sccond shilt rciictor Io fonn n sccond Khifi renctor cflluent. In such mothodn, it ir. parlicularly prcfcncd thnt the sccond poition is combined with the first shift reactor effiuent in an amount effective to reduce steam consumption in the first and second shift reactors. Wilh respect to the compononts, conditions, nnd furlher configurations, the same concidcrations as provided above apply. Various objecta, features, aspeeti and advimtagei of tho prosenf invention will become more apparenl from the following detailed description of prefelred embodlments ofthe invention along with thc diawing. Dctniled Dcscrlptlou In most curveritly known configurations for production of hydrogen from synthesis gas, and particularly from synthesis gas with high carbon monoxide to hydrogen ratio, steam is typically rcquircd in quantities far in oxcess ofthe amount required by Btoichiomerry for the shift reaction (CO + H2O -> H2 + CO2). The inventors now unexpectedly discovered that the cxcess steam used in the production of hydrogen from syngas predominantly servea to limit the tempcrature risc across the catalytic reactor, as the shift reaction îs higlily exothermic (AH is about -40.6 KJ/mol). Thcrcfore, Iho inventors contemplate n procesa configuration in which oxidntion of i CO to CO2 is spread over at least one additional shift reactor to reduce heat generation. In one prcfcned aspect of the inventive subjcct niatter, the inventors contemplate a plant in which a first fraction ofthe total feed gas is bypassed around a first shift reactor to reduce the nmount of produccd hoat nud thus to rcduco llie omourit of required stearn. A Bccond fraction ofthe totnl fced gns in combined with the.processed first fraction und then fed into a second shift reactor to complete the convcrsion of tlio totnl fccd gnu. One exemplary contctnplated configuration is depictcd in Flgurc l in which a plant 100 includes a shift conversion unit having a futil shift reactor 110 and a sccond Bhifl reactor 120. Syngas siream 101 (or syngas strcam 102 where a bypass ÎR employed; sec bclow) is eplit into a first portion 102' and a second portion 102", wherein the first portion (here: about 40 vol% of total feed gas stream 101 or 102) is combined with steam 130 to form stream 103. The second feed portion 102" (here: about 60 vol% of total feed gas stream 101 or 102) bypasses the fi r a l shifl reactor 110, Strenm 103 nmy be picheated by feed prcheater 140 before entering first shift reactor 110. The first shift'reactor effiuent 112 is then cooled by effluent cooler 150, and the cooled effluent 112 is combined with the second portion 102" to form mixed feed stream 112', which is then fcd to the second shift rcnclor 120. The cffluent 122 from the second shift reactor 120 muy bc combincd with bypass strcum 101' (whicli may bc drnwn from the nyngan strcarn 101 lo control total conversion) to form liydrogcn rich product stream 122', For compnrison, f ilar Art FIgurc 1 dcpicts n typictil stcam shifl configvirntion 200 in which a first shift reactor 210 and a second shifl reactor 220 providc conversion of a syngas streinii 201 to n hyilioj!,en rich product strcnin 222' with the same aniount of CO shitted to H2 as the previous casc (i. e., same H2 to CO ratio as in stream 222'), Moto purllculurly, flyngnii stream 201 is dividcd into feed stream 202 (typically about 83 vol% of syngas stream 201) and bypass stieam 201' (typically about 17 vol% of syngas stream 201). The syngas stream 202 is combined with steam 230 to form stream 203, which is preheated by feed prchcatcr 240 bcforc cntcring tho first shift reactor 210. The cfflucnt 212 from first shift reactor 210 is tlien cooled by efflucnt cooler 250 and is fcd to the sccond shift reactor 220, The cfflucnt 222 from the second shift reactor 220 is combincd with bypass stream 210' (to control conversion) to form hydrogen rich product stream 222'. BgompliFy ealeulBted GompoiIllonUi flow rn!s§f and temperatursi 9f in tho iihmtft ncetwlinfi; to Pigmeu l mul 2 nro iiulicnted in tho Tnblen of Flgiires 3 nnd 4, respcclively. In the tables, columns with underlined numerals at the top refer to slrcams in Figures l nnd Zdenotod with corrosponding numernls in diamonds, Thus, it should be recognized that tlie inventors contemplate a plant comprising a first shift reactor and a second shift reactor, wherein the first shift reactor receives a first portion of a syngflR from n gn s i fi cu t io n unit or n pnrlinl oxidntion unit and forma n first shift reactor eflluent, and wherein the second shift reactor receives a combination of the first shift reactor offiuent nnd a sccond portion of tho syngas to form a second shift reactor efflucnt. With respect to suitable feed gascs it is contemplated that various gases are deemed ;i|!|ir..|ill.i!.- •>.m|im l Ion of ("n f lypirnlly ni lonftl 5-II) ninl'hi, unu» ly|ilt>nlly ni Imiul .M) inul'lii, mul numi lj|ilriill:y ni h-nni -Ml ninl'if,) l liMiHini'i tho chemicnl compoHlIlon ol'lhe tued gius mny vmy coimlilmnlily, HIK) n |iniiU;iilm ciuiipnnlllmi will predominantly dcpend on the specific origin of the feed gas. Howcvcr, it is espccially prcfcrred that the feed gas is a syngas from a gasification plant or parţial oxidation unit. Thus, particularly prefeircd feed gases will typically have a carbon monoxide to hydrogen ratio in excess of 2.0, more typically in excess of 2.2, and most typically in excess of 2.4 (e,g., typical syngas comprises 50 mol% carbon monoxide, 20 mol% hydrogen, the balaricc including nitrogen, carbon dioxicle, sulfurous compounds, and inert gases). Fiuthcrmore, it is conlomplntod llmt (ho feed gns pressure mny vary considerably, and it should be npprecinlcd thnt suilnble prcssures include a wide range, typicnlly between 50 and 1500 pai, 'llius, wlioro suitnblo n focd gan boostor or coniproKKor niay bc employed whcrc tlie fced gns prcssurc is rclntivcly low, Alternatively, and espccially whcre the feed gas pressure is rclntivoly high, n turbino oxpander or othcr pressure reducing dovice mny bc used to reduce a pressure dcsircd for tho shift reaction, With respect to the splitting of tho feed gas stroarn, it is generally contcmplated that the first portion and the second portion may vary considerably, and suitable first portions are typically between 5% and 100% of the feed gas flow before the split into first and second portions, Wlicro thc feed gas is (or comprises) syngas ftom a gasification reactor or parţial oxidation unit, it is e.spccially prefcrrcd that the first portion of the fced gas is between about 25 vol% to about 70 vol% , and more prcferably between 35 vol% to about 45 vol% of tlie feed gas. Conscqucntly, suitublo second portions will be in thc rangc of 0% and 95% of the feed gas flow before the split into first and Becond portions. Howevcr, prcferred second poilioiui wlll lypiuiilly înngo botwoon 50 vol% Io 73 vol% ofllio riyngiiH (Vom tho niiuKicatlon unit or parţial oxidalion unit. Moreover, and especially where it is desirable to control the final composition of the proccsscd fced gas, contcmplated plante may furllicr include a bypnss Uiat combines part of thc fced gns with thc cffluent gns from tho socond shifl reactor. It is further contetnplated that thc particular nmount of feed gas that is bypasscd around the first and second shift reactors i may vary considerably, and genevally contemplated aniounts are between O vol% and about 25 vol%, and more lypically between about O vol% and about 15 vol%. Bnscd oii cnlunlnlioiis using coi>fip, and CVCM liij/Jicr (as compnrcd Io n configuiiitioii williout bypnss of thc first sliifl reactor and same opcrrUing pnramclcrs ns cxcmplilicd in thc Inblcs). Tho so snved stonm nmy thcn bc utilizcd for other proccsscs, and ospecially for the generation of power. For cxamplc, in a commcrcialsized powcr plant with a total cquivăleni powcr capacity of 400 MW, Ihe cnlculatcd powcr Iha t niay bc gcncratod from Iho savod stoam is in oxcoss of 50 MW, Alternatively, or additionally, the syngas may also be humidified in a humidifier. In such configurnlions, it is goncrnlly conlornplnlcd llinl tho omount of watcr uscd by the humidifier may be significantly reduced by splilting the hurnidifîed feed gas as already doacribed above, Thus, contemplatori plani also include thosc In which the syngas is humidified in a humidifier before ontcring the first shift reactor, wherein the sccond portion of the syngas is combincd with thc first shifl reactor cffluent in an amount effcctive to reduce watcr consumption of the humidifier by at least 10%, morc typically at Icast 20%, and even morc typically at Icast 30% (as comparcd Io a configuration without bypass of thc first shift reactor and same operating parnmeters as exemplified in the tables). It should be especially notcd thnt in confîgurntions whoro Iho stonm is introduced by humidificntion of Iho syngns, contoinplhlod configiunlioiiH will noi only ruduco Iho nmount of honl icqnlrcd by Iho humidifier but also tho stzc of t!\e cquipment associated with the humidificalion operation. In nddition to rcducing tho slenm usngc or oxtcnt of humidificntion, it should be rccogni?.cd thnl contcmplntcd configurntlons will nlso reduce thc nmount of comlonsnlc gcncrated downstrcnin of tho shifl unit(s) whcn the shifted gas is coolcd for carbon dioxide removal, which advantageously reduces the amount of condensate to be treated. Moreover, in at leasl some inslanccs, thc inlet temperanire of the second shifl reactor in convenţional conflgurations (see e.g. Figure 2) is determined by the dew poiiit of the feed gas. Li contrast, thc dew point of thc fccd gas Io thc second shift reactor in contcmplatcd configuralions is lower (as comparcd to convenţional configurations), and thus thc secorid reactor may be opernted closer to its optimum opernting tcmpcrnture without boing constrnined by thc dew point of thc fccd gas. Similar ndynntnges were also obsorved in cnlculatlons for configurntionfl nccording to Figure 5, in which n bou l 44% of Iho fccd syngns wns bypassed around thc first reactor with no additional bypass around the second reactor. The same configuration as depicted in Figure 5 was operated without bypass around the first reactor to serve as a comparative example for calcuhtions shown in the tablcs of Flgurc 6 (opcrating conditions) and Figurcs 7A-7D (mntcn'nl bnlnnoos), Tho torni "nboul" wlicn unocl horcln In conjunction willi n numeral rcfcrs (o a value rangc o!'•)/- 10%, inclusive, of thc valuc of that numeral. Tho cojifiguratlon of Figurc 5 is pnrticulnrly suited for an IGCC plan^ with CoP gasifiors nnd boilere to provide export sleom to the rcfinery. However, in alternative embodiments, it should be recognized that the tail gas may be compressed and supplied to the gns Uirbinos of tho IGCC, or rocyclcd nt Icn.qt in part nfior C02 oxtrnction to iocrciiHo 112 procluction. Calculated dnta were developed in the two cases for a constant molar rate of H2 contained in the PSA feed gas and are summarized below: (Table Removed) As cnn be sccn in thc above table, the slcam ond catalyst rcquircments as wcll aj thc condensate produccd downstrcarn of tho shift unit aro slgnificantly reduced. Morcover, the size of the heat exchangers for the contemplated shift units are also significantly reduced. The sizc of thc PSA unit on tho other Imnd will be larger In the case of the improved shiA design since the amount of gas to be treated in the PSA unit is slightly higher while its H2 concentrai ion lowor. It should furthcrbe notcd tliat the larger amount (energy content) of tail gas generated in tlio PSA unit In «ucli conflguratlons tliyplncos nn equivuleiit nmount of «yngns (unshiftcd) that would be fircd în thc boilers in the IGCC plant. In other applications of coproducing power and IJ2, and especially whcre low prcssurc fuel gns is not requircd, the PSA tail gat) mny bc coinprcsscd aud supplied to the gas turbine aftcr combining wilh the syngas, or a portion of it may be treated to remove tlie C02 and recycled to the shift unit to generate ndditionnl H2. With respect to the shift rcactors, it should be rccognized that al] known types and sir.ns înny ho uscd in coiy'nnctioM vvitli llio confipuintion nccoiding to Iho invcnllvo nubjcct inatlcr, and may furthcr compriso ono or inoic suilablo cnlalysts, For cxarnplc, whcre the shifl rcaction is perfmnied ni a relatively bigh temperature (e.g., about 590-720 °K), (lie catalyst may be based oi; iron-oxide, On trie other hand, where thc shift reaction is pcrformod at a relatively low temperatura (e.g., about 470-520 °K), Cu-, Zn-, and/or Al-based catalyst may bc cmploycd. Similnrly, it should be nppreciatcd that all known feed heatcra and effluent coolors urc suitablc for usc in conjunction wilh the tcachings presented herein. It should still further be appreciated thnt confîgurations and niothoda according to thc inventive subjecl matler are espcciaUy suitnble for plants in which dcep carbon monoxide conversicm is not rcquired (e.g., remaining carbon monoxide in stream 122' between5-15 mol%, and move typically betwecn 5-10 inol%). For exainple, suitablc plants include those that coproduce a fucl gas that may be supplied to B gas turbino or fuel cell and/or a fired equipment (e.g., using a fimiace or boiler), whcToin tlie higli purity hydrogcn for such plantfi is providcd via membrancs and/or a pressure swing adsorption unit that purifies the shifted gas. AUcrnatively, coutemplatcd mctlipds and configuraticns may a!so bc cmployed as retrofit in various peirochcmical plants tliat consume hydrogen, which is currently generated from nnturnl gns. Rcplncemcnt of such hydvop.cn production whh hydrogcn production from gasificalion of aitcmalive fuels (e.g., rcfinery residues or coal) may be especially advantageous in vicw of cnvitonmental as well as economical aspccts. Among othcr things, penahies for carbon dioxide emission may bc rcduced using contemplated configurations in whicli hydrogen is pixxluced from syngas generaled from coal or othcr chcap fuel and combufllod in (Ins gn.s linblno of a coiubined cyclo, whilo the carbon dioxide Is scparated from thc shiftcd gas using nn acid gas removal unit nud sequcstcved. In still nnothcr cjtuiuplc, coutctiijilalcd configurations an (c.g., plants proilucing mcthanol, dinicthyl ctlicr, Fischcr Tropsch liquids, ctc.) (hat rcquirc adjustment of the carbon monoxide to hydrogen ratio in the fced gns. Therefore, the inventors contemplate a method of opcrating a plant (and particularly to reduce steam consumption in a shift convcrsion processcs in such operations), in which in oue step n first ulii fi reactor n ml a acicorul ulii U ronctor nro providcd. In nnothcr «top, n Byngno fced fiorn n gnslficnlion unit or n părtini oxiclntlon unit is spllt Into a first portlon and a second portion, and the llrst portion is fed to the first shift reactor to form a first shifl reactor effluent. Li still another step, the first shift reactor effluent is combined with the sccond portion to fonti a mixed fecd gas, nnd the mixcd fced gns is renclcd in the sccond shift rcnctor to form a socoml Hhitt roiiclor offliionl, whcrcln Iho nccond porllon IB comblncd wlth tlio firnt «hlft reactor effluent in an nmount effective to reduce steam consumption (via separate steam strcnm or via humidiftcation) in tlie first and second shift rcactors, Furtliennore, it should be noted that contemplated configurations and methods are not limitcd to two-reactor systems. For cxnrnplc, n sciics of thrce or rnore reactors may bc utilizcd in which tlic gas by-passed nround ono rcnctor is fed to n rcnclor downiHronm of that reactor. Thu», apociflo embodirnenl» and nppllcntlons of Improved configurations and procossos for n sliift ronction hnvo bcon disclosod. It Bhould bo nppurcnt, howovcr, to UKDBO skillcd in thc ai t tlint many more modifications besidcs thosc nlrcndy describcd are possible without dcparting from the inventive concepts herein. The inventive subject matter, therefore, is not to bc rcstricted exccpt in tlic spirit of the claims. Morcovcr, in interpreting bolh the spccification and the claims, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the temis "comprises" and "comprising" should be intcrprctcd as rcfcuing to clcmcnls, componcnts, or stcps in n non-exclusivc rnanncr, indicaling thnt the reforenccd clcmcnls, componcnts, or slcps may bo prcsenl, or utilizcd, or combined with other elements, componcnts, or steps that are not cxpressly referenced. We claim: 1. A plant with improved configuration for shift conversion comprising: a first shift reactor (110) and a second shift reactor (120), wherein the first shift reactor (110) receives a first portion of a syngas (102') from a gasification unit or a partial oxidation unit and flows out as first shift reactor effluent (112); and wherein the second shift reactor (120) receives a combination of the first shift reactor effluent (112) and a second portion of the syngas (102") to form a second shift reactor effluent (122) and wherein the first shift reactor is with or without a humidifier or acid gas removal unit. 2. The plant as claimed in claim 1, wherein the second portion (102") has a volume between 50 vol% to 75 vol% of the syngas from the gasification unit or partial oxidation unit. 3. The plant as claimed in claim 1, wherein the syngas entering the first shift reactor is humidified in a humdifier, coupled to the first shift reactor (110). 4. The plant as claimed in claim 1, wherein the second shift reactor effluent (122) is combined with a third portion of the syngas through a bypass. 5. The plant as claimed in claim 1, wherein in the syngas, carbon monoxide and hydrogen are in a molar ratio of at least 2:1. 6. The plant as claimed in claim 1, wherein carbon dioxide from the second shift reactor effluent (122) is removed by an acid gas removal unit, which is coupled to the second shift reactor (120).

Documents:

3154-DELNP-2005-Abstract-(29-07-2008).pdf

3154-delnp-2005-abstract.pdf

3154-DELNP-2005-Claims-(15-12-2008).pdf

3154-DELNP-2005-Claims-(23-12-2008).pdf

3154-DELNP-2005-Claims-(29-07-2008).pdf

3154-delnp-2005-claims.pdf

3154-DELNP-2005-Correspondence-Others-(15-09-2008).pdf

3154-DELNP-2005-Correspondence-Others-(15-12-2008).pdf

3154-DELNP-2005-Correspondence-Others-(23-12-2008).pdf

3154-DELNP-2005-Correspondence-Others-(29-07-2008).pdf

3154-delnp-2005-correspondence-others.pdf

3154-delnp-2005-description (complete)-29-07-2008.pdf

3154-delnp-2005-description (complete).pdf

3154-DELNP-2005-Drawings-(29-07-2008).pdf

3154-delnp-2005-drawings.pdf

3154-DELNP-2005-Form-1-(29-07-2008).pdf

3154-delnp-2005-form-1.pdf

3154-delnp-2005-form-13-(19-05-2008).pdf

3154-delnp-2005-form-18.pdf

3154-DELNP-2005-Form-2-(15-12-2008).pdf

3154-DELNP-2005-Form-2-(29-07-2008).pdf

3154-delnp-2005-form-2.pdf

3154-DELNP-2005-Form-3-(15-12-2008).pdf

3154-delnp-2005-form-3.pdf

3154-DELNP-2005-Form-5-(29-07-2008).pdf

3154-delnp-2005-form-5.pdf

3154-DELNP-2005-Others-Document-(15-09-2008).pdf

3154-delnp-2005-pct-101.pdf

3154-delnp-2005-pct-210.pdf

3154-delnp-2005-pct-220.pdf

3154-delnp-2005-pct-237.pdf