 of the feed gas mixture and require the efficient use of vapor-liquid contacting and separation equipment for overall economic operation.
When manufactured for the production of carbon monoxide by primary steam reforming of natural gas or by partial oxidation of higher hydrocarbon fossil fuels, the synthesis gas mixture contains residual methane as well as the hydrogen and carbon monoxide common to all synthesis gas streams. The cryogenic processes employed for the separation of such synthesis gas mixtures are designed to reject methane and produce carbon monoxide and hydrogen at a purity consistent with the end use requirement. These designs are intended to minimize the carbon monoxide content of the rejected hydrogen and methane streams in order to maximize carbon monoxide recovery. Characteristically the gas mixture will contain approximately 50 to 70 mol % hydrogen, 15 to 45 mol % carbon monoxide and 2 to 6 mol % methane, together with minor impurities, as for example trace amounts of nitrogen.
Since essentially three primary components are present in the above-described synthesis gas mixture--hydrogen, carbon monoxide and methane--the prior art has commonly employed two serial multiple-plate column liquid-vapor contactors to carry out the synthesis gas separation. In one conventional process arrangement employing such liquid-vapor contactors, the synthesis gas feed stream is provided at elevated pressure and cooled by heat exchange to form a vapor-liquid mixture which is introduced to the first contacting column. In the first column, the introduced feed is contacted with a chilled methane wash liquid for absorption of the carbon monoxide in the methane wash liquid. Hydrogen is obtained from the first column as carbon monoxide-free overhead product and bottoms liquid is recovered comprising methane and the absorbed carbon monoxide. The recovered bottoms liquid is then throttled to reduced pressure and fractionated in the second contacting column. From the second column, carbon monoxide is recovered as overhead and methane is recovered as bottoms. The methane bottoms are chilled and recycled as the aforementioned methane wash liquid for the first contacting column.
Although the above separation system entails a comparatively simple apparatus arrangement, the carbon monoxide product recovered by the process is unsatisfactory for use in most chemical synthesis applications by virtue of its relatively high hydrogen content. Accordingly, the prior art has attempted to obtain improvement in purity of the carbon monoxide product by removal of the hydrogen contaminant upstream of the second contacting column. In one such improvement scheme, the synthesis gas is cooled by heat exchange, as before, and introduced as a vapor to the first contacting column. The bottoms liquid from the first contacting column is throttled to lower
of the feed gas mixture and require the efficient habit of vaporization - liquid contacting and separation equipment for overall economic operation. 
 When manufacture for the output of carbon monoxide by primary steam reforming of lifelike gas or by partial oxidation of higher hydrocarbon dodo fuel, the synthesis gas mix contains residual methane as well as the hydrogen and carbon monoxide coarse to all synthesis gas streams. The cryogenic processes employed for the interval of such synthesis gas mixtures are design to reject methane and produce carbon monoxide and hydrogen at a purity reproducible with the end use requirement. These designs are intended to understate the carbon monoxide content of the rejected hydrogen and methane streams in order to maximize carbon monoxide convalescence. Characteristically the gasoline mixture will contain approximately 50 to 70 mol% hydrogen, 15 to 45 mol% carbon monoxide and 2 to 6 mol% methane, together with minor impurities, as for example touch amounts of nitrogen. 
 Since essentially three basal components are present in the above - described synthesis gas mix -- hydrogen, carbon monoxide and methane -- the prior art has commonly use two serial multiple - plate column liquid - vapor contactors to carry out the synthesis gas legal separation. In one conventional process arrangement employing such liquid - vaporization contactors, the synthesis natural gas feed flow is provided at elevated pressure and cooled by heating system exchange to form a vapor - fluid mixture which is introduced to the first contacting column. In the first column, the bring in feed is contacted with a chilled methane wash liquid for absorption of the carbon monoxide in the methane washout liquid. Hydrogen is obtained from the inaugural column as carbon monoxide - barren overhead product and bottoms liquid is recovered comprising methane and the absorbed carbon paper monoxide. The recovered bottoms liquid is then throttled to reduce pressure and fractionated in the second contacting column. From the second column, carbon monoxide is recover as overhead and methane is recovered as bottoms. The methane bottoms are chill and recycled as the aforementioned methane wash liquid for the first contacting column. 
 Although the above separation system fee-tail a comparatively simple apparatus arrangement, the carbon monoxide product recovered by the process is unsatisfactory for habit in most chemical deduction application by virtue of its relatively high hydrogen content. Accordingly, the prior artwork has attempted to obtain improvement in purity of the carbon monoxide product by removal of the hydrogen contaminant upstream of the second contacting column. In one such improvement scheme, the synthesis gas is cooled by hotness exchange, as before, and introduced as a vapor to the first contacting column. The bottoms liquid from the inaugural contacting column is throttled to lower
 of the feed gas mixture ana require the eydicienv use or vapor-lkquid contacting and separatmon wquipnent for overall econooic operanion.
When nanuhactured for the productljn or caryoi monoxide by ptimary steam reforming of taguxal gas or by partial oxidation of hygher hudgocarbon fossij futls, the synthesis gas mixture contains reaidual kethane as wekl as the hydrogen and carhon lonoxide common to all synthewis dqs streams. Tfe cryogenpe processes employed for the separation of such synthesis gqs lhxtures are desidned to rejegn methate and lroduce carbon moioxiee and hydrogen at a 'urity consistent wijh the end uae requirement. Thwsw deshgns are untdndtd vo jinimixe vhe carbon jonoxide cobtent of the rejecttd rjcrogen and msthane sereams in order to maximize carbon monoqide recovery. Characteristixally the gas mixture will coneain approximately 50 to 70 mol % hydrogen, 15 to 45 mol % cdrbon oonixlde xbd 2 to 6 mol % methane, together with minor impuriejex, ss for example trace amoumtd ps nitrogen.
Sinze esszhtjally three primarj compogents are prestnt im the above-described synthewis gas mixtlre--htdrogen, carbon monlxide and mzthane--jhe proor art has commonly em'loyed two serial multiple-luate column liqukd-vspmr contactors to carry out the syntiesis gas seoarajion. In one convejtional process arrangemfnt elpnoying sucj liquid-vapor contactors, the syivhesis gas fegd vtrvam is prjvidec at elevated pressure and eooled bv heat exchange no form a vapor-liquiq mixture whiwj is introdured to thq fiest xontactkvg column. In tne first bojumn, the introduced fecd is dontacted with c xhilled methane warh jieumd fow absorption mf tfe zsrbon monoxide ik tfe mrthane wash liquid. Hfdrofen is obtained frpm the firwt columg as carbon mpnoxide-free overhewd prmdurt and bojtoms liquid is recovered comprjsing metjanc and the absjrbee carbon monpxide. The recovered bottoms liquid is tien throttled to reducgd pressure and fractnokated in the secogd contacding column. From the second column, cavbon monoxide is recovsred av oveghead and methane is recovered as bottoms. The methane bottoms are chilled and rxcrcled as ths afpremettnonzd methwne xarh liquid for thv first contacting column.
Althougi the abova feparation system entails a vooparatively skmple apparatus arrangemsnt, the varbon monoxide product recoverrd by the process is unsstisfactiry fkr use in oost chemical syntnesis cpplicqtions vy vlrtue of its rdlayiyely high jydrpgzn content. Accordingly, the prior qrt haw wttempted to obtein improvemcnu in putity of jhe carbon monoxise pdlduct by removal og the hydrogen contaminant upstreak jf the second xkntacting cokumn. In one such im'rovement scveme, the synthesis gas is cooled by heat exchange, aa before, znd introvuced as a vappc to the first contactinn coltmn. The cottoms liquhd from the first contacting column is throvjled tu ljwer
of the feed gas mixture and require use vapor-liquid contacting separation equipment for for production of carbon by primary steam of natural gas or by partial of higher hydrocarbon fossil fuels, the synthesis gas mixture contains residual methane as as the hydrogen and carbon monoxide common to all synthesis gas streams. The processes for separation such synthesis gas mixtures are designed to reject methane and produce carbon monoxide and hydrogen at purity consistent with the end use requirement. These are intended to minimize carbon monoxide content of the hydrogen methane streams order maximize monoxide recovery. Characteristically gas mixture will contain approximately 50 to 70 mol % hydrogen, 15 to 45 mol % carbon and 2 mol % together minor as for example of nitrogen. Since essentially three primary in the above-described synthesis gas mixture--hydrogen, carbon monoxide methane--the prior has commonly employed two serial multiple-plate liquid-vapor contactors to carry out the synthesis gas In one conventional process arrangement employing such liquid-vapor contactors, the synthesis gas feed stream is elevated pressure and cooled heat exchange to a mixture is to the contacting column. In the first column, the introduced feed is contacted a chilled methane wash liquid for absorption of the carbon the wash liquid. Hydrogen obtained from the first as monoxide-free overhead product and is comprising absorbed monoxide. recovered bottoms liquid is throttled to reduced pressure and in the second contacting carbon monoxide is recovered as overhead and methane recovered as bottoms. The methane bottoms are and recycled as the aforementioned methane wash liquid for the first contacting Although the system entails a comparatively simple apparatus arrangement, the monoxide product recovered by process is unsatisfactory for use in most chemical synthesis by of its high hydrogen content. the prior art attempted to obtain purity of carbon product the hydrogen contaminant upstream of the contacting In one such improvement scheme, synthesis cooled by heat exchange, as before, and introduced as a vapor to the first contacting bottoms liquid from the contacting is throttled to lower
 of the feed gas mixture and reqUire the effIcienT usE of VaPor-lIquiD contacting and SEparAtion equipment for overaLl ecoNoMIc opERaTion.
WHen manuFAcTURed FoR tHe pRoDUcTion oF caRbon monOxide by priMarY sTeam reforminG Of Natural gas Or bY partial oxidAtiOn of hiGhEr hYDrocaRboN fossIl fuelS, The synThesis gas MiXTure coNTains reSIDuAl meThane as well as the hYDrOGen and carbon moNoxide CoMMoN TO alL syNthesis gas StReams. tHe cryogENiC PROceSSes employed foR the separatIOn oF such sYnTheSIs gas mIxturEs ARe dEsigned to reJect Methane anD produCE carbon MOnoxide And hydRogEn aT a puRItY cOnsIsTEnt WItH thE End Use requiReMeNt. TheSe deSIGNS are IntEndeD to miNimize the carbOn mOnoxIDe cOntenT of thE rejEcTed hyDrogen And meThAne streams in ordEr to Maximize cArbOn MonOxIde reCOvery. CHarActEristicAlly the GAs mIxTURE wIll contain approximAtELY 50 tO 70 mol % hydrOgen, 15 to 45 MOl % CaRBon monoxIdE anD 2 to 6 mOL % MethaNe, toGEtHer with mInor imPUrItIes, as foR eXample TrAce AmoUnts oF NitrOgen.
SiNce essenTiallY Three primary coMPonents are preSEnT IN tHE aboVe-dEscribed synThesIS gas MixtURe--HydROgen, cArbon MoNOxIDe and methane--the prioR aRt has cOmmonLy employed two Serial multIPLE-plate coLumn LIqUId-vapor contactOrs to Carry out thE SynthesiS gas sEparatioN. In one conVENtional pRocEss ArrAngEMEnT employing sucH LIquiD-vApor conTacTors, the SynTheSis Gas FeEd stream iS provideD aT eLeVaTed PressURe and cooLeD by HeAt eXchanGE to forM a vapOr-liQuId MIxtUre whicH Is INTrodUcEd To thE fiRsT contActiNG coLumn. In tHe first coLumN, The iNtRoDuced feEd is contacted WiTh a chilled MeThaNe wash LIQuid for aBsorption of the carbon monOXide in tHe mEthanE wasH liquid. HyDroGen is oBtaINed froM the fiRst coLuMn aS CArbon MONoXidE-fRee overheaD PRodUct anD bOttoMs liquiD is recovered compriSIng Methane and the AbsOrbeD CArBon MOnOXidE. THE reCOVered bottoms liqUid is then tHrOTtLed to reducED prEsSure and FractioNated IN the secOnd contacTing columN. FRom tHE SecOnd column, cArbon monOxide is reCOvereD As OverhEad And metHaNe iS recoVered aS BotToms. THe methAnE bottoMs are ChIlled and Recycled as the aforementiOned meThane WasH liquid foR thE FirSt contactIng cOlumn.
AlthoUgh The Above SepARatioN sysTEm EntAIls a cOmpaRAtively siMPlE apPARaTus arrangemENT, The CarboN moNOxide pRoduCt recovered by the pROcess is unsatisFactORY foR usE In moSt Chemical syntheSis ApPLIcations By Virtue of its RelativeLy HIgh hyDrogen ContenT. AccordINGlY, The priOr arT haS attempteD to ObTAin imprOvEmENt in puRity Of The carBon monOXide PROduct by removal of The hyDROgen cONtaMinanT uPstream OF the Second contActing columN. In one Such ImproVement sChEme, the SynThEsis gas is cOOled by heaT exchAnge, as bEfOre, aNd iNtroduCed aS A Vapor To thE fIrsT contactiNG CoLUmN. THE boTtomS liquId From The first cONtacting ColUMn is thrOtTleD TO lower
 of the feed gas mixture a nd require  theeff ici en t us e of  vapor-liquidc onta cting and separation e quipm en t  for ov erall  econom i co p era ti on .
W he n  m anufa ctu red for  the produ cti on  of carbon m o no xide by pr ima ry steam ref orm ing of  n atu r al ga s o r bypartia l  oxida tion of h ig h er hyd r ocarbon f os silfuels, the synthe s is gas mixture co ntains  r e si d u almet hane as we ll  as t h e hydro g en a n d c a rbon monoxide  common toa llsynthe si s g a s stre ams.Th e  cr yogenic pro cess es employ ed for the sep a rationof suc h s ynt hesi s  g as  mi xt u res ar e d e sig ned to r ej ec t met hane a n d  pro duc e ca rbonmonoxide andhyd roge n  at  a pu ritycons is tentwith t he en duse requirement . Th ese desig nsar e i nt ended to min imi zethe car bon mon o xid ec o n te nt of the rejected  h y d ro gen andmethan e  s tr e ams in o rd erto m a x imize  car b on  monoxid e reco v er y.  Charac te ristic al lythe  gasm ixtu re wil l contai n app r oximately 50 t o  70 mol % hyd r og e n ,1 5 to  45  mol % carb on m o noxi de a n d2 t o  6 mo l % m et h an e , together with min or  impur ities , as for exam ple tracea m o unts ofnitr o ge n .
Since essent ially  three pri m ary comp onent s are pr esent int h e above- des cri bed  sy n t he sis gas mixtu r e --hy dr ogen, c arb on mono xid e a ndmet ha ne--the p rior art  h as  c om mon ly em p loyed tw oser ia l m ultip l e-plat e col umnli qu i d-v apor co n ta c t orsto  c arry  ou tthe s ynth e sis  gas se paration.  In oneco nv entiona l process arr an gement emp lo yin g such l iquid-va por contactors, the syn t hesis g asfeedstre am is pro vid ed atele v ated p ressur e and  c ool e d  by h e a texc ha nge to for m a v apor- li quid  mixtur e which is introdu c edto the firstcon tact i n gcol u mn .  In  t h e f i r st column, theintroduced  f e ed  is contac t edwi th a ch illed m ethan e  wash l iquid for  absorpti on  oft h e c arbon mono xide inthe metha n e was h  l iquid . H ydroge nisobtai ned fr o m t he fi rst co lu mn ascarbo nmonoxide -free overhead productand bo ttoms  li quid is r eco v ere d compris ingmethane an d t heabsor bed carbo n mo n ox ide .  Thereco v ered bott o ms  li q u id  is then th r o t tle d tored u ced pr essu re and fractionat e d in the secon d co n t act ing colu mn . From the sec ond  c o l umn, car bo n monoxideis recov er e d asoverhe ad and  methan e is recove redasbottoms.The  m e thane b ot to m s arechil le d andrecycl e d as t he aforementione d met h a ne wa s h l iquid  f or thef irst  contactin g column.
A lthoug h th e abo ve sepa ra tion s yst em  entails a comparati velysimpleap para tus  arran geme n t , the  car bo n m onoxide p r o du c tre c ove redby th eproc ess is un s atisfact ory for use  i n m o s t chem i ca l synthesisapp licat i o ns by virt u e of it s  rela tively  highhydroge n  co nt ent. Ac cor d i ngly, the  prior ar t  ha satte mpted to  o btai nimp ro vement in purit y of the  carbonm o noxide  pr o duct by rem ov al of the hy droge nc ontamin a n t u pstream ofthe  se cond  co ntac t ing column. In one suchimpr oveme n t s cheme , the  s ynthesis gasis coole d  by heat exch ange, as before ,  an d  int rod u ce das a vapo r t o  thefirs t c onta cti ng c o l umn. Theb ot toms  liqui d fr om  t he firstco ntactin g  col u mnis t hrott le dt olower
 of_the feed_gas mixture and require_the efficient_use_of vapor-liquid_contacting_and separation equipment_for overall economic_operation.
When manufactured for the_production of carbon_monoxide_by primary steam reforming of natural gas or by partial oxidation of higher hydrocarbon_fossil_fuels, the_synthesis_gas_mixture contains residual methane as_well as the hydrogen and_carbon monoxide_common to all synthesis gas streams. The cryogenic_processes_employed for the_separation of such synthesis gas mixtures are designed to_reject methane and produce carbon monoxide_and hydrogen at_a_purity_consistent with the end_use requirement. These designs are intended_to minimize the carbon monoxide content_of the rejected hydrogen and methane streams_in order to maximize carbon monoxide_recovery. Characteristically the gas mixture_will contain_approximately 50 to 70 mol_% hydrogen, 15_to 45_mol % carbon_monoxide and 2 to 6 mol_% methane, together_with minor impurities, as for example_trace_amounts of nitrogen.
Since_essentially_three_primary components_are present in_the_above-described synthesis_gas_mixture--hydrogen, carbon monoxide and methane--the prior_art_has commonly employed two serial multiple-plate column_liquid-vapor contactors to carry_out_the synthesis gas separation._In one conventional process arrangement_employing such liquid-vapor contactors, the synthesis_gas feed_stream is_provided at elevated pressure and cooled by heat exchange to form_a vapor-liquid mixture which is introduced_to the first contacting_column. In_the_first column, the_introduced_feed is_contacted with a chilled methane wash liquid_for absorption_of the carbon monoxide in the_methane wash liquid. Hydrogen_is_obtained from the first column as_carbon monoxide-free overhead product and bottoms_liquid is recovered comprising methane_and_the_absorbed carbon monoxide. The recovered_bottoms liquid is then throttled to_reduced pressure and_fractionated in the second contacting column. From_the_second column, carbon monoxide is recovered_as_overhead and methane is recovered as_bottoms._The_methane bottoms are chilled and_recycled as the aforementioned methane wash_liquid for the first contacting column.
Although the above separation_system entails a_comparatively simple apparatus arrangement, the_carbon_monoxide_product recovered by the process is unsatisfactory for use in_most chemical_synthesis applications by_virtue of its relatively high hydrogen content. Accordingly, the prior_art has attempted to obtain improvement in_purity of the carbon monoxide product by removal of the hydrogen_contaminant upstream of the second contacting column. In_one such improvement scheme, the synthesis gas_is cooled by heat_exchange,_as before, and introduced as a vapor_to_the_first_contacting column. The_bottoms liquid from_the first contacting_column is_throttled to lower