 is used to reboil oxygen bottom liquid in a lower pressure column.
The demand for lower purity oxygen is increasing in applications such as glassmaking, steelmaking and energy production. Less vapor boilup in the stripping sections of the lower pressure column, and less liquid reflux in the enriching sections of the lower pressure column are necessary for the production of lower purity oxygen, which has an oxygen purity of less than 98.5 mole percent, than are typically generated by the operation of a double column.
Accordingly, lower purity oxygen is generally produced in large quantities by a cryogenic rectification system wherein feed air at the pressure of the higher pressure column is used to reboil the liquid bottoms of the lower pressure column and is then passed into the higher pressure column. The use of air instead of nitrogen to vaporize the lower pressure column bottoms reduces the air feed pressure requirements, and enables the generation of only the necessary boil-up in the stripping sections of the lower pressure column either by feeding the appropriate portion of the air to the lower pressure column reboiler or by partially condensing a larger portion of the total feed air.
While the conventional air boiling cryogenic rectification system would be effective for the production of lower purity oxygen, its ability to generate liquid nitrogen reflux for supply to the top of the lower pressure column is limited. This results from the lower component relative volatilities at the operating pressure of the higher pressure column which is similar to that of the main air feed and because of the large fraction of liquid air produced in the process compared to a conventional double column process. More power is consumed because oxygen recovery is reduced as a result of the reduced capability to generate liquid nitrogen reflux.
Accordingly, it is an object of this invention to provide a cryogenic rectification system for producing lower purity oxygen wherein the liquid bottoms of a lower pressure column are reboiled by indirect heat exchange with feed air and which operates with reduced power requirements over that of conventional air boiling systems.
Often it is desired to recover the product oxygen gas at an elevated pressure. Generally this is carried out by compressing the product gas to a higher pressure by passage through a compressor. Such a system is effective but is quite costly. Moreover, air boiling cryogenic rectification systems have heretofore been most useful for the production of lower pressure oxygen.
Accordingly, it is another object of this invention to provide an air boiling cryogenic rectification system which can effectively produce elevated pressure oxygen gas without the need for oxygen gas compression thus further reducing power
is used to reboil oxygen bottom liquid in a lower pressure column. 
 The demand for low honor oxygen is increasing in applications such as glassmaking, steelmaking and department of energy production. Less vaporization boilup in the stripping sections of the low pressure column, and less liquid ebb in the enrich sections of the low pressure column are necessary for the production of lower purity oxygen, which has an oxygen purity of less than 98.5 mole percentage, than are typically generated by the operation of a double column. 
 consequently, lower purity oxygen is generally produced in large measure by a cryogenic rectification system wherein feed air at the pressure of the high pressure column is used to reboil the liquid bottoms of the lower pressure column and is then passed into the higher pressure column. The use of air instead of nitrogen to vaporize the lower pressure column bottoms reduces the breeze feed pressure requirements, and enable the coevals of entirely the necessary boil - up in the stripping section of the lower pressure column either by feeding the appropriate portion of the tune to the lower pressure column reboiler or by partially condensing a larger portion of the total feed atmosphere. 
 While the conventional air boiling cryogenic rectification system would be effective for the product of lower honor oxygen, its ability to render liquid nitrogen reflux for supply to the top of the humble pressure column is limited. This results from the low part relative volatilities at the operating pressure of the higher pressure column which is like to that of the main air feed and because of the bombastic fraction of liquid breeze produced in the procedure compared to a ceremonious double column process. More power is consume because oxygen recovery is reduce as a result of the reduce capability to generate liquid nitrogen reflux. 
 consequently, it is an object of this invention to provide a cryogenic rectification system for produce lower purity oxygen wherein the liquid bottoms of a lower pressure column are reboiled by collateral heat exchange with feed air and which operates with reduced power requirements over that of conventional tune boiling system. 
 Often it is desired to recuperate the product oxygen gas at an exalted pressure. Generally this is carried out by compress the product gas to a higher pressure by passage through a compressor. Such a organization is effective but is quite costly. Moreover, air boiling cryogenic correction systems have heretofore been most useful for the production of lower pressure oxygen. 
 Accordingly, it is another object of this invention to provide an air travel boiling cryogenic rectification system which can effectively produce elevated pressure oxygen gas without the need for oxygen gas compression thus far reducing power
 is used to reboil oxygen buttom liquid in a lowec presshre coluon.
The demand for lower puritb oxtgen us increasing in applizations slch as glqssmeking, steelmakinj and encxgy pdlducciin. Less vapor noilup in tve stripping sacgilns of the lower pressure column, anq less kieuid reflux in the qnridhing sections of the lower pressude colukn are necesssry for the production of poweg purity oxygen, whlch has an ixygqb purity of uess than 98.5 mole percenj, than are typically generated bh the operation od a gouble colunn.
Accjrdingly, lowcg puritf oxygem is generally prmduxed in large quantitixs by a cryogenic restificatimn system wherein fwee air at dhe oeesrurt oh tge higjer pressure dolumn is uwed to reboil the loqtpc bottoms of the ljwqr pressure column and is then passed itto the higher pressure cooumn. The use of air ijstead of nitrogen to vaporize the lower pressure column bmttoma rebmges gye air feed pressure requirements, and enables trs bekeration of only the necesssrj njil-up in the rtrippnhg sections of the llwer prgssure column eythet by feeding the appropriatw portion of rhe air to the lowzr pressure eolumn rebooler or by partially coudensihg a larger portion kw the total feed aig.
Whine the conventional air boyling cryigennc rectiwicajion syftem would be enxective for the prlductnon ox lower pugity oxygen, its ability to genecete liquid nijrocen reflux yor suiply to the top of the lower kressure eolumn is limites. This cesults from the lower cokkonent relatite volatijitiws ar the oodrating pressute of the higher prwssure column whicm is rjmilar to that if uhw main air feec avd febauxe mf the large fraztium of uiquid air iroaucec in the process com[ares to a conventionak qouble cilumn prjcess. More poeer is consumed befause oxbgen rrcodery is reduced as a result of the redufed capability eo gcnerwte liquid nitrogen reflux.
Accordingly, it is an oboect of this invention ro provide a cryogeuig rectificatmon syftem for [roducing lower puriry oxygen wherein the liquid bottoms or a lofer pgessure column are reboiled by indirect heat exchange with feed air and wyich o'ewates with deduved pmwzr xequireientd over that of comventional air boiling systems.
Ohten it is dzsired to recover the product obygen gas at xn elevated pressure. Gensrally tnis is carried out by compressimg the product gas to a migher prwssurs by passaje through a compresxor. Sueh a ststem iw efnective but is quotc costly. Mlreoter, air boiling cryogenic rectificarion stshems have heretohore been modu usefum for jhe production of lowsg prersure oxygen.
Avcordingly, it os another object of tris invention uo provide an aor boilpng cryogenic rectificathon system which can effectively produce elevated ptessure oxyfen gas wmthout the neec for oxygen gas comprexsyon thus further redgcing power
is used to reboil oxygen bottom liquid lower column. The for lower purity such glassmaking, steelmaking and production. Less vapor in the stripping sections of the pressure column, and less liquid reflux in the enriching sections of the lower column are necessary for the production of lower purity oxygen, which has an purity less 98.5 percent, than are typically generated by the operation of a double column. Accordingly, lower purity oxygen generally produced in large quantities by a cryogenic system wherein feed air the pressure of the higher column used to the bottoms the lower pressure and is then passed into the higher pressure column. The use of air instead of nitrogen to the lower bottoms reduces air pressure and enables the only the necessary boil-up in the the lower pressure column either by feeding the portion of air to the lower pressure column or by partially condensing a larger portion of total feed air. While the conventional air boiling cryogenic rectification system would be effective for of lower purity oxygen, ability to generate nitrogen for to top of lower pressure column is limited. This results from the lower component volatilities at the operating pressure of the higher pressure column similar that of the air feed and because the fraction of liquid air the compared double process. power is consumed because recovery is reduced as a of the reduced capability Accordingly, it is an object of this invention provide a cryogenic rectification system for producing purity oxygen wherein the liquid bottoms of a lower pressure column are by indirect with feed air and which operates with reduced requirements over that of air boiling systems. Often it is desired to recover product gas at elevated pressure. Generally is carried out compressing the product a higher by through a system is effective but is costly. air boiling cryogenic rectification systems heretofore useful for the production of lower pressure oxygen. Accordingly, it is another object of this provide an air boiling rectification which can effectively produce elevated pressure oxygen gas without the need for compression thus further
 is used to reboil oxygen bottoM liquid in a Lower PreSsuRe ColuMn.
ThE demand for loweR PuriTy oxygen is increasing in AppliCaTIons SUcH as glAssmakiNG, sTEElmAkInG anD eNErGy proDucTion. LesS vapor boilUp iN tHe stripping sECtIons of the lOweR pressure colUmn, And lesS lIquID reflUx iN the eNrichiNG sectiOns of the lOwER pressURe columN ARe NeceSsary for the producTIoN Of lower purity oXygen, wHiCH hAS An oXygEn purity of LeSs thaN 98.5 Mole perCEnT, THAn aRE typically genErated by the OPerAtion oF a DouBLe coluMn.
AccOrDIngLy, lower puriTy oxYgen is genErally PRoduced IN large qUantitIes By a CryoGEnIc RecTiFIcaTIoN sySTem Wherein fEeD aIr at tHe prESSURe of The HighEr preSsure column is UseD to rEBoiL the lIquid BottOmS of thE lower PressUrE column and is theN pasSed into thE hiGhEr pReSsure COlumn. THe uSe oF air insTead of nITroGeN TO VaPorize the lower presSuRE CoLumn bottOms redUCeS tHE air feed PrEssUre rEQUiremEnts, ANd Enables tHe geneRAtIoN of only ThE necesSaRy bOil-Up in tHE strIpping Sections Of the LOwer pressure coLUmn either by feEDiNG ThE ApprOprIate portion Of thE Air tO the LOwEr pREssurE coluMn REbOIler or by partially coNdEnsing A largEr portion of thE total feed AIR.
while the ConvENtIOnal air boiling CryogEnic rectifICation syStem wOuld be efFective foR THe producTioN of LowEr pURItY oxygen, its abiLITy to GeNerate lIquId nitroGen RefLux For SuPply to the Top of the LoWeR pReSsuRe colUMn is limiTeD. ThIs ResUlts fROm the lOwer cOmpoNeNt RElaTive volATiLITies At ThE opeRatInG presSure OF thE higher Pressure cOluMN whiCh Is Similar To that of the maIn Air feed and BeCauSe of thE LArge fracTion of liquid air produced IN the proCesS compAred To a convenTioNal douBle COlumn pRocess. more pOwEr iS COnsumED BeCauSe Oxygen recoVERy iS reduCeD as a Result oF the reduced capabilITy tO generate liquId nItroGEN rEflUX.
ACCorDiNGly, IT Is an object of thiS invention To PRoVide a cryogENic ReCtificaTion sysTem foR ProduciNg lower puRity oxygeN wHereIN The Liquid bottOms of a loWer pressuRE coluMN aRe rebOilEd by inDiRecT heat ExchanGE wiTh feeD air anD wHich opErateS wIth reducEd power requirements over That of ConveNtiOnal air boIliNG syStems.
OfteN it iS desired to RecOveR the pRodUCt oxyGen gAS aT an ELevatEd prESsure. GeneRAlLy tHIS iS carried out BY COmpRessiNg tHE produCt gaS to a higher pressurE By passage throuGh a cOMPreSsoR. such A sYstem is effectiVe bUt IS Quite cosTlY. Moreover, aiR boiling CrYOgeniC rectiFicatiOn systeMS HaVE heretOforE beEn most useFul FoR The prodUcTiON of lowEr prEsSure oxYgen.
AcCOrdiNGLy, it is another objEct of THIs invENtiOn to pRoVide an aIR boiLing cryogeNic rectificAtion sYsteM whicH can effEcTively ProDuCe elevated PRessure oxYgen gAs withoUt The nEed For oxyGen gAS ComprEssiOn ThuS further rEDUcINg PoWEr
 is used to reboil oxygenbottom liq uid i n a  lo we r pr essu re column.
The dema nd for lower purity ox ygenis incr e as ing i n appli c at i o nssu ch  as  g l as smaki ng,  steelm aking andene rg y production .  L ess vaporboi lup in the s tri ppingse cti o ns of  th e low er pre s sure c olumn, an dl ess li q uid ref l u xin t he enriching sect i on s  of the lowerpressu re co l u mnare  necessary  f or th e  produc t io n o f l o wer purity ox ygen, which has  an ox yg enp urityof le ss tha n 98.5 mole  per cent, tha n aret ypicall y  genera ted by  th e o pera t io nofad oub l ecol u mn. 
Accordi ng ly , low er p u r i t y ox yge n is  gene rally produce d i n la r gequant ities  byacryog enic r ectif ic ation system wh erei n feed ai r a tthe  p ressu r e of t hehig her pre ssure c o lum ni s us ed to reboil the l iq u i dbottomsof the lo we r  pressur ecol umna n d isthen pa ssed int o theh ig he r press ur e colu mn . T heuse o f  air  inste ad of ni troge n  to vaporize t h e lower press u re c ol u mn b ott oms reduces  the airfeed pr ess u re re quire me n ts ,  and enables the ge ne ration  of o nly the neces sary boil- u p in the s trip p in g  sections of t he lo wer pressu r e column  eith er by fe eding the a ppropria tepor tio n o f th e air to thel o werpr essurecol umn reb oil erorbypa rtially c ondensin gala rg erporti o n of the  t ota lfee d air . 
While  theconv en ti o nal  air bo i li n g  cry og en ic r ect if icati on s y ste m would  be effec tiv e  for  t he  produc tion of lower  p urity oxyg en , i ts abi l i ty to ge nerate liquid nitrogenr eflux f orsuppl y to  the topofthe lo wer pressu re col umn i slim i t ed. T h i sres ul ts from th e low er co mp onen t relat ive volatilities a t  th e operating p res sure o fthe hi g her  p r ess u r e column whichis similar  t o  t hat of the mai nair fee d and b ecaus e  of the  large fr action of  l iqui d air  producedin the p rocess co m pared to  a co nve ntiona ldou ble c olumnp roc ess.More p ow er isconsu me d becaus e oxygen recovery is re ducedas ares ult of th e r e duc ed capabi lity  to genera teliq uid n itr o gen r eflu x .Acc o rding ly,i t is an o b je cto f  t his inventi o n toprovi dea  cryog enic  rectification sy s tem for produc ingl o wer  pu r ityox ygen wherein t heli q u id botto ms  of a lower  pressur ec olumn  are r eboile d by in d i re c t heat  exc han ge with f eed  a i r and w hi ch operat es w it h redu ced po w er r e q uirements over t hat o f conve n tio nal a ir  boilin g  sys tems.
Ofte n it is des ired t o re cover  the pr od uct ox yge ngas at ane levated p ressu re. Gen er ally  th is iscarr i e d out  byco mpr essing th e pr o du ct gas  toa hig he r pr essure by passagethr o ugh a c om pre s s or. Su c ha system iseff ectiv e but is qui t e co s tl y . Mor eover,  air b oilingc ryo ge nic rec tif i c ation sys tems have her et ofor e been m os t us ef ulfo r the productio n of low er press u r e oxyg en. Acco r dingly ,it is anothe r obj ec t  of thi s inv entiont o p rov ide  anair  boi l ing cryogenic rectificat ionsyste m  wh ich c an ef fe ctivelyp rodu ce eleva t ed pressure o xygen gas witho u t t h e ne edf or  o xygen gas  co m press ionthu s fu rth er r e d ucin g  pow e r
 is_used to_reboil oxygen bottom liquid_in a_lower_pressure column.
The_demand_for lower purity_oxygen is increasing_in applications such as_glassmaking, steelmaking and_energy_production. Less vapor boilup in the stripping sections of the lower pressure column, and_less_liquid reflux_in_the_enriching sections of the lower_pressure column are necessary for_the production_of lower purity oxygen, which has an oxygen_purity_of less than_98.5 mole percent, than are typically generated by the_operation of a double column.
Accordingly, lower_purity oxygen is_generally_produced_in large quantities by_a cryogenic rectification system wherein feed_air at the pressure of the_higher pressure column is used to reboil_the liquid bottoms of the lower_pressure column and is then_passed into_the higher pressure column. The_use of air_instead of_nitrogen to vaporize_the lower pressure column bottoms reduces_the air feed_pressure requirements, and enables the generation_of_only the necessary_boil-up_in_the stripping_sections of the_lower_pressure column_either_by feeding the appropriate portion of_the_air to the lower pressure column reboiler_or by partially condensing_a_larger portion of the_total feed air.
While the conventional_air boiling cryogenic rectification system would_be effective_for the_production of lower purity oxygen, its ability to generate liquid nitrogen_reflux for supply to the top_of the lower pressure_column is_limited._This results from_the_lower component_relative volatilities at the operating pressure of_the higher_pressure column which is similar to_that of the main_air_feed and because of the large_fraction of liquid air produced in_the process compared to a_conventional_double_column process. More power is_consumed because oxygen recovery is reduced_as a result_of the reduced capability to generate liquid_nitrogen_reflux.
Accordingly, it is an object of_this_invention to provide a cryogenic rectification_system_for_producing lower purity oxygen wherein_the liquid bottoms of a lower_pressure column are reboiled by indirect heat exchange with_feed air and_which operates with reduced power_requirements_over_that of conventional air boiling systems.
Often it is desired to_recover the_product oxygen gas_at an elevated pressure. Generally this is carried out by_compressing the product gas to a higher_pressure by passage through a compressor. Such a system is effective_but is quite costly. Moreover, air boiling cryogenic_rectification systems have heretofore been most useful_for the production of_lower_pressure oxygen.
Accordingly, it is another object of_this_invention_to_provide an air_boiling cryogenic rectification_system which can_effectively produce_elevated pressure oxygen_gas without_the need for_oxygen_gas compression thus further reducing power