US2579498A - Process for producing oxygen - Google Patents

Process for producing oxygen Download PDF

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US2579498A
US2579498A US717672A US71767246A US2579498A US 2579498 A US2579498 A US 2579498A US 717672 A US717672 A US 717672A US 71767246 A US71767246 A US 71767246A US 2579498 A US2579498 A US 2579498A
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air
line
nitrogen
rectification
heat exchange
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Frank J Jenny
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Hydrocarbon Research Inc
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Hydrocarbon Research Inc
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air

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  • This invention relates to the production of oxygen by the liquefaction and rectification of air, and more particularly to an economical method of obtaining oxygen in high purity and in high yield without the use of chemical reagents to effect the removal of carbon dioxide present in air.
  • Oxygen is commonly produced by partial liquefaction of air and rectification at low temperatures; preferably rectification is conducted in two stages at different pressures.
  • the refrigeration necessary for liquefaction is supplied to the air, after it has been compressed and water-cooled to approximately room temperature. by indirect heat exchange with the effluent products of rectification.
  • an additional amount of refrigeration must be supplied to compensate for cold losses resulting from the difference in enthalpy between the incoming air and the outgoing products of rectification and for heat leaks into the system.
  • Methods of supplying this refrigeration heretofore used involve compressin at least a portion of incoming air to pressures as high as 3000 pounds and expanding with or without the performance of work to produce a temperature drop; or compressing all the incoming air to about 600 pounds and after the air has been partiall cooled by the products of rectification expanding a portion of the air. These methods are wasteful from the standpoint of compressor energy and require a great deal of equipment in the form of extra compressors, intercoolers and expanders.
  • Another object of this invention is to provide a process for producing oxygen of high purity and in high yield from air with greatly reduced equipment and power costs as compared with existing procedures.
  • a stream of air is passed through a path in a heat exchange zone, a stream of rectification product is passed through another path in the heat exchange zone in heat exchange relation with the air passing therethrough, the air being thus cooled to a temperature close to its condensation point at the pressure existing in the heat exchange zone so as to substantially completely remove all carbon dioxide present in the air.
  • the expander may be operated without encountering the troubles heretofore experienced because carbon dioxide was solidified in the expander during the expansion of the air stream.
  • a minor portion of the thus cooled air stream is thereafter warmed by heat exchange with one of the warmer streams of fluid media fiowing in the system, preferably by passage through the aforesaid heat exchang zone, to a temperature such that upon subsequent expansion little or no condensation or formation of liquid air in the expander takes place with consequent further improvement in the operation of the expander.
  • the thus warmed minor portion is expanded to produce the refrigeration necessary to compensate for cold losses resulting from the difference in enthalpy between the incoming air and the outgoing products of rectification and for heat leaks into the system, and the expanded air is introduced into the rectification system where it is rectified to recover the oxygen content thereof.
  • the remaining major portion of the air is also introduced into the rectification system where it is rectified to recover the oxygen content thereof.
  • the flow of air and that of the rectification product are periodically reversed through their respective paths in the heat exchange zone so that upon each of the reversals the rectification product substantially completely removes the carbon dioxide deposited during the preceding step of the process.
  • a stream of air at about 60 to about 100 pounds and a temperature of about 70 to about 110 F. is passed through a path in a heat exchanger containing at least three fiow paths in heat exchange relation with each other through one of which passes a stream of oxygen or nitrogen product of rectification.
  • the stream of air leaving the first-mentioned path and cooled to a temperature below about 270 F. but above its condensation point is divided into two streams, one comprising the major portion of the air flowing to the rectification system, and the other comprising the remaining minor portion, say from 15% to 35% by volume of the total air introduced into the process.
  • the thus warmed air stream is expanded to produce the refrigeration necessary to compensate for cold losses resulting from the difference in enthalpy between the incoming air and the outgoing products of rectification and for heat leaks into the system.
  • the low pressure stage is preferably operated under a pressure of from about 4 to about 10 pounds, preferably at about 5 pounds; the high pressure stage is maintained at a pressure of from about 60 to about pounds.
  • a temperature difference in the range of from about 5 to about 10 F'., preferably about 6 to about 8 F. This is accomplished by passing the cold rectification product stream in heat exchange relation with a warmer stream in the system thereby conservin the refrigeration in the rectification product stream and warming this stream to a temperature of from about 5 to about 10 F. below the temperature at which the air stream leaves the exchanger.
  • the warmed rectification product stream at this temperature is introduced into its flow path in the exchanger.
  • the flow of air and that of nitrogen or oxygen through their respective paths are reversed so that upon reversal the air flows through the path through which during the preceding step the nitrogen or oxygen had passed and the nitrogen or oxygen flows through the path through which had previously passed the air.
  • the nitrogen or oxygen removes, by sublimation or evaporation, the carbon dioxide and the frost, if any, deposited in the exchanger during the preceding step.
  • Figure 1 illustrates diagrammatically a preferred layout of apparatus for practicing the process of this invention
  • FIG 2 illustrates a modified arrangement of heat exchangers which may be used in lieu of the exchangers shown in Figure 1;
  • FIG. 3 illustrates a modified arrangement of apparatus for practicing the process of this invention
  • FIG 4 illustrates still another modified arrangement of heat exchangers which may be used in lieu of the exchanger shown in Figure 3.
  • each of the reversing exchangers of Figures 1 to 4 inclusive may be replaced by two or more smaller exchangers placed in series and/or parallel, if desired; other rectification systems may be used in lieu of those shown in Figures 1 and 3 including rectification systems equipped with means for purging the high pressure stage to remove incondensible gases such as helium, hydrogen and neon therefrom, or the rectification system of Figure 1 may be used with the exchangers of Figures 3 and 4 or the rectification system of Figure 3 may be used with the exchangers of Fi ures 1 and 2.
  • I is a heat exchanger which may be of any well-known type.
  • it consists of a single shell in which are provided three flow paths, namely, interior path II and concentric paths i2 and I3 disposed in heat exchange relation with each other.
  • the heat exchanger has in each of the paths suitable fins of heat conducting material. e.g., copper or aluminum, promoting rapid and eflicient heat exchange between the gaseous media flowing therethrough.
  • suitable fins of heat conducting material e.g., copper or aluminum, promoting rapid and eflicient heat exchange between the gaseous media flowing therethrough.
  • each flow path in an exchanger is shown on the drawings as consisting of a single tube, the several paths being disposed concentrically. Actually, however, each path in each exchanger may comprise a multiplicity of tubes for flow therethrough.
  • Paths I2 and I are the paths through which air and nitrogen flow. the flows of these two media through their respective paths being periodically reversed so that during one step of the process air flows through path l2 and nitrogen through path l3. and upon reversal during the suceeding step air flows through path I3 and nitrogen through path l2. Reversal of flow is accomplished by suitably positioning the compound reversing valves l4 and it which may be of any well-known type. Valve I4 is disposed in the pipe line system consisting 01 (a) air inlet pipe I5 leading into valve II, (b) nitrogen exit line H leading to any suitable point of nitrogen disposal and (c) pipe lines l3 and i3 leading to one end of paths i2 and I3. respectively.
  • lead from the other end of the exchanger from paths l2 and i3. respectively, to valve IS.
  • a line 22 leads from valve I5 to an air line 23, portion 24 of which leads into a line 25 communicating with path II.
  • a valve 26 in line 25 controls how therethrough.
  • valve 25 By suitably positioning valve 25, a portion of the total air which is to be expanded. say from about 10% to 100% by volume, preferably about 10% to 35%, flows through line 25 into and through path II where the air is warmed, imparting most of its cold content to the air flowing in a countercurrent direction.
  • the thus warmed air leaves path ll through line 21 communicating with a pipe line 23 leading into an expander 29 which may be a centrifugal expander or turbine of any well known type.
  • Leading into line 28 is an air line 3
  • the remaining portion of the total air to be expanded flows from line 23 through line 30 into line 28 where it mixes with the warmed air entering line 28 from line 21.
  • the resultant air mixture thus being warmed to a temperature such that no condensation or formation of liquid air takes place in expander 23 with consequent improvement in the eiilciency of the expander operation.
  • the expanded air leaves expander 23 through line 32 leading into the low pressure stage of a rectification system hereinafter described.
  • a second heat exchanger 33 is provided in the form of a shell having therein flow paths 34. 33 and 36 each provided with fins to promote heat exchange as in the case of the exchanger Iii.
  • Path 35 is the path through which a minor portion of the nitrogen product of rectification flows from the rectification system hereinafter described by way of a pipe line 31 communicat ing with path 36. Flow through line 31 is controlled by valve 33. The nitrogen product of rectification leaves path 36 through line 33 which leads into the nitrogen line 40 communicating with valve l5 associated, with the heat exchanger l3.
  • Oxygen and air periodically flow through paths 34 and 33 in heat exchange relation with each other and with the nitrogen flowing through path 33.
  • the flows of air and oxygen through their respective paths are periodically reversed so that during one step of the process air flows through path 34 and oxygen through path 35 and upon reversal during the succeeding step air flows through path 35 and oxygen through path 34.
  • communicates with the main air line through a pipe line 43 and is connected by lines 44 and 45, respectively, to the warm end of the paths 34 and 35.
  • is provided with an oxygen exit line 45' leading to a suitable oxygen storage tank or point of consumption.
  • Valve 42 is connected to the cold end of paths 34 and 35 by lines 48 and 41. respectively.
  • Air line 43 leads from valve 42 to the main air line 23. Oxygen is supplied to valve 42 through the line 43 which leads from the rectification system hereinafter described.
  • minor nitrogen stream may be passed through flow path II in exchanger It in heat exchange relation with the air and nitrogen streams fiowing through the other two paths in this exchanger and the minor air stream passed through flow path 33 in heat exchanger 33 in heat exchange relation with the air and oxygen passing through the other two flow paths in this exchanger.
  • Reversing exchangers l3 and 33 may be placed in vertical, horizontal or any other desired position. When these exchangers are arranged vertically the colder end may be above or below the warmer end. While two exchangers have been shown, it will be understood that any desired number may be employed. In general, the nitroren flow paths through the exchangers should have approximately four times the volumetric capacity of the oxygen flow paths. If desired. exchangers in which the oxygen and nitrogen flow paths are of the same volumetric capacity may be employed in which case tour air-nitrogen rcversing exchangers are employed for each airoxygen reversing exchanger. Also, of the total air cooled by indirect heat exchange with the oxygen and nitrogen products of rectification, about 20% flows through the air-oxygen reversing exchanger and about 80% through the air-nitrogen exchanger.
  • the rectiflcation system 58 comprises two columns and 52.
  • is operated at a pressure of from about 60 to about 100 pounds, preferably at about 70 to 75 pounds and column 52 at a pressure of from about 4 pounds to about pounds, preferably at about 5 pounds.
  • These columns are provided with rectiflcation plates of the bubble-cap or other desired type.
  • Air is supplied to the base portion of the high pressure column 5
  • a line 63 leads from the top of column 5
  • An expansion valve 65 is disposed in branch 63.
  • expanded air from expander 29 enters the low pressure column 52 through line 32.
  • the base of this column is provided with a line 61 passing through the nonreversing heat exchanger 6
  • function as a reboiler; liquid oxygen flows through line 81 through exchanger 6
  • Nitrogen line 10 leads from the top of column 52 through exchangers 64, 51 and 55 and communicates with line 40 leading to the valve l5 of reversing heat exchanger Ill and line 31 which communicates with the flow path 35 in reversing heat exchanger 33.
  • air from the main air line is divided into two streams, one of which flows through line I6, valve
  • the air stream is thus cooled to a temperature near its condensation point and all carbon dioxide and moisture, if any, removed therefrom and deposited in the flow path l2.
  • a portion of this air stream flows through line 24, valve 25, line 25 through flow path II where it is warmed by heat exchange with the countercurrent air stream.
  • the warm air stream leaves this flow path through line 21 and flows into line 28.
  • Another portion flows from line 23 through valve 3
  • the expanded air from expander 29 flows through line 32 and enters the low pressure stage of the rectification system.
  • the thus warmed nitrogen stream mixes with the major portion of the nitrogen flowing from line 10 through line 40 and the mixture enters valve
  • Another air stream flows from the main air line through line 43, valve 4
  • the air cooled to a temperature close to its con densation point leaves flow path 34 through line 46 and enters valve 42 leaving this valve through line 48 which communicates with the air line 23.
  • From line 23 a minor portion of the air as hereinabove described flows through line 30.
  • the remaining major portion flows through line 53 into non-reversing exchanger 54 where the air is further cooled by the oxygen flowing in indirect heat exchange relation therewith through line 49.
  • exchanger 54 the air flows through exchanger 55 where it is still further cooled by flowing in indirect heat exchange relation with the nitrogen passing through this exchanger, the thus cooled air entering the high pressure column 5
  • the air entering high pressure column is rectified, crude oxygen is withdrawn from the base of this column through line 55, chilled by flowing in indirect heat exchange relation with the nitrogen stream in exchanger 51, flashed by flowing through expansion valve 59 so that it is still further cooled and introduced into the low pressure column 52 at 58.
  • the gaseous stream consisting chiefly of nitrogen flowing through line 03 of the high pressure column 5
  • the gaseous stream is thus substantially condensed, liquid flowing through line 82 into column 5
  • All of the air passed to the expander 29 may be warmed by passage through section iIlB instead of dividing a minor portion of the chilled air to be expanded into two streams one of which passes through flow path H in exchanger Ill and is thus warmed and then mixed with the other stream flowing through line to, the mixture being introduced through line 28 into the expander 29 as in the modification of Figure l; and
  • section IDA is provided with two reversing flow paths HA and HA for flow of air and nitrogen therethrough.
  • Section NIB is provided with reversing flow paths I23 and HE for flow of air and nitrogen therethrough. Paths HA and I2B are connected by a line H and flow paths ISA and I3B by line I2.
  • Section IIIB also contains a flow path IIB for flow of a minor portion of the cooled air stream therethrough, this flow path leading into a line 13 which connects the exit end of the flow path to expander 28.
  • Section 33A is provided with two reversing flow paths 34A and 35A for flow of air and oxygen therethrough and section 33B is provided with flow paths 34B and 358 for flow of air and oxygen therethrough.
  • Flow path 34A is connected with flow path 348 by a line I4 and flow path 35A with 353 by a line 15.
  • Section 33B also contains the flow path 3GB for flow of a minor portion of nitrogen therethrough, the exit end of this flow path communicating with a line 15 which leads to the nitrogen line 40.
  • Each of the flow paths hereinabove described have suitable walls and flns of heat conducting material, e. g., copper or aluminum, promoting rapid and efficient heat exchange between the gaseous media flowing therethrough.
  • the line 48 leading from valve 42 is provided with a line 48'. flow through which is controlled by valve 48" for introducing, if desired, some of the cold air flowing through line 48 into the warm air stream flowing through line 13 into the expander 29. thereby permitting more accurate control of the temperature of the air entering expander 29.
  • Line 48' corresponds to line 33 of Figure 1 except that line 48 leads from line 48 and not from the air line 23 as in Figure 1. I! desired. line 48 may lead from line 23 as is the case with line 30 of Figure l.
  • Oxygen from line 49 leading from the low pressure stage of the rectification system passes through heat exchanger 54 into valve 42, line 41, flow path 353, line 15, flow path 35A, line 45, valve 4I into the oxygen exit line 45'.
  • a minor portion of the nitrogen stream flows through line 31, flow path 353, line 16 into line 49 where it mixes with the major portion of the nitrogen stream, the resulting mixture flowing through valve I5, line 29, flows path I2B. line 1
  • Oxygen flows through line 49, valve 42, line 49, how path 34B, line 14, flow path 34A, line 44 and valve 4
  • an exchanger such as 33 of Figure l in which the nitrogen stream flows through the entire length of the exchanger may be used with a sectional exchanger involving sections WA and I9B as shown in Figure 2 through which the air stream to be warmed passes through only one of the sections of the exchanger.
  • a sectional exchanger corresponding with sections 33A and 33B of Figure 2 may be used with an exchanger such as exchanger I9 of Figure l in which the air stream to be warmed passes through a flow path extending the full length of the exchanger.
  • exchanger 89 is employed, provided with flow paths BI and 82 for flow of air and nitrogen, the flows of these two mediums being periodically reversed through their respective flow paths.
  • a flow path 83 in heat exchange relation with the other flow paths is provided for uni-directional flow of oxygen.
  • a flow path 84 is provided for uni-directional flow of a minor portion of the chilled air stream leaving the exchanger to effect reheating of this air stream prior to its introduction into the expander 29.
  • a flow path 85 is provided for unidirectional flow of a minor portion of the nitro gen stream, the warm nitrogen stream leaving flow path 95 as hereinafter more fully described, mixing with a major portion of the nitrogen stream to elevate the temperature of the mixed nitrogen stream which is passed through flow path 9
  • each of the flow paths is provided with suitable walls and tins of heat conducting material, e. g., copper or aluminum.
  • the various flow paths are arranged in concentric relationship.
  • the main air line leads to a valve I4 disposed in the pipe line system consisting of a nitrogen exit line I1, a line I9 communicating with the warm end of flow path 9
  • and 92 communicate with line 29 and 2
  • Line 22 leads from valve I5 into a line 95, one branch of which leads to the rectification system and another branch 91 of which is provided with a valve 99 and leads to the inlet of the flow path 94.
  • a branch line 99 leads from line to a line 99, leading into the expander 29.
  • Flow through branch line 99 is controlled by valve 9
  • a minor portion say about 2%, flows through line 81, valve 99, flow path 94 into line 92 leading into line 99.
  • Another minor portion say about 18%, flows through valve 9
  • the expanded air flows through line 32 to the low pressure stage of the rectification system hereinafter described.
  • the rectification system of Figure 3 comprises a two-stage rectification column 93, the lower section 94 of which is operated at a pressure of about 69 pounds to about 100 pounds, preferably about '70 to 75 pounds, and the upper section of which is operated at a pressure of from about 4 pounds to about 10 pounds, preferably at about 5 pounds.
  • This column as is customary, is provided with rectification plates of the bubble-cap or other desired type.
  • the lower section 94 communicates with a condenser 95 and has a liquid collecting shelf 91 disposed immediately below the condenser 96 for collecting liquid nitrogen. Pipe line 99 leads from this shelf 91 to a non-reversing heat exchanger 99 which in turn communicates through pressure reducing valve I99 with the top portion of the upper section 95.
  • Condenser 96 acts as a reboiler for the upper section 95.
  • for the flow of crude oxygen passes to a non-reversing heat exchanger I92 which communicates through pipe line I93 having a pressure reducing valve I94 therein with the low pressure section 95 at an intermediate point I95.
  • a line I96 having a pressure reducing valve I91 therein leads from condenser 95 to nitrogen line I98 leading to the non-reversing heat exchanger I99 through which the nitrogen passes in indirect heat exchange relation with the air stream flowing through line 86 to the high pressure section 94.
  • I9 leads from the top of low pressure section 95 to heat exchanger 99, the nitrogen flowing through this line passing through the heat exchanger 99, then through line III to heat exchanger I92, and then through line 2 which communicates with line I99.
  • An oxygen line II3 leads from the lower part of low pressure section 95 to one end of flow path 93, the other end of this flow path being provided with an oxygen exit line II4.
  • a line I I5 leads from exchanger I99 for flow of notrogen therethrough.
  • Line I I5 is provided with a branch I I6, flow through which is controlled by valve II1.
  • Branch line IIB leads into one end of flow path 95, the other end being provided with an exit line III! which leads into the nitrogen line I
  • a valve I29 I3 may be disposed in the portion 01 line Ill leading into line I I9.
  • Nitrogen flowing through line I98 from lines I96 and H2 passes through the heat exchanger I99 as hereinabove described.
  • a minor portion 01 this nitrogen stream flows through valve Ill and line IIG into flow path 85 where it is warmed by heat exchange with the gaseous mediums passing through the other how paths in exchanger 80, the warm nitrogen leaving through line H9 and flowing into line II9 where it mixes with the major portion of the nitrogen stream entering line 9 from line H5.
  • the resulting mixed nitrogen stream passes through valve I5, line 2
  • oxygen flows from the low pressure section 95 through line H3, flow path 83 and leaves through the oxygen exit line I I4.
  • Air flows from the main air line through valve II, line I9, flow path 82, line 2
  • the mixed nitrogen stream produced in line ll9 by nitrogen flowing thereinto from lines H8 and IIS flows through valve 15, then through line 29, flow path BI, line III. valve I4, and exits through the nitrogen exit line II.
  • the exchanger modification of Figure 4 differs from that of Figure 3 chiefly in that the exchanger I26 has four flow paths therethrough which are identified by the same reference characters as those used to indicate the like flow paths of Figure 3; the flow path 85 for flow of a minor portion of nitrogen therethrough to be warmed prior to mixing with the major portion oi the nitrogen rectification product is not employed in the modification of Figure 4.
  • a separate non-reversing exchanger I29 which exchanger may be of any well known type in which efllcient cold exchange takes place, is used.
  • a line I21 having valve I22 therein leads from the nitrogen line I I5 to an exchanger I26.
  • a line I29 leads from this exchanger to the nitrogen line II9 leading to valve I5.
  • Line 92 leading from the warm end of flow path ll passes through exchanger I26, the warm air flowing through line 92 giving up a portion of its heat to the minor portion of the nitrogen passing through exchanger I26 and thus warming this nitrogen stream to a temperature such that. upon mixing with the remaining major portion of the nitrogen, the resulting mixture has a temperature of from 5 to 10 F. below that oi the air stream exiting from the colder end of the exchanger I25.
  • the reversing exchanger of Figure 4 has the advantage over that of Figure 3 that it is less costly due to the elimination of one of the flow paths in the reversing exchanger; as a practical matter it has been found less expensive to emloy a separate exchanger I26 than to build a reversing exchanger having an additional flow path corresponding to flow path of Figure 3.
  • the minor portion oi the nitrogen may be passed through flow path 94 and the thus warmed nitrogen passed through exchanger I26 in indirect heat exchange relation with an air stream passing to expander 29. the air thus being heated to a temperature such that no liquid air forms in expander 29 upon expansion 0! the warmed air stream.
  • the nitrogen stream leaves exchanger I29 at a temperature such that when mixed with the remainder of the nitrogen product of rectification the mixture has a temperature within 5 to 10 F. below that of the exiting air stream at the colder end of exchanger I25.
  • Air under pressure of about 74.6 Pounds and at a temperature 01' 95 F. is supplied through line I9, valve I4, line III to the flow path I2 and through line 43, valve II, line H to the flow path 34' of heat exchangers III and 23. respectively.
  • the air leaves flow path I2 through line 25, valve l and enters line 22 flowing into line 23: the other air stream leaves flow path 34 through line 46, valve 42 and flows through line 43 into line 23.
  • the air is thus cooled to a temperature of 276.5 and the oxygen stream warmed to a temperature of -283 F. at which temperature it enters flow path 35 of exchanger 33.
  • the air at a temperature of -276.5 F. passes through the heat exchanger 55 in heat exchange relation with the nitrogen stream flowing through line 1
  • the temperature differential between the entering oxygen stream and the exiting air stream at the colder end of exchanger 33 is 8 F.
  • the air flows through paths l3 and 35 in exchangers I0 and 33, respectively, nitrogen through path l2 in exchanger NJ and oxygen through path 34 in exchanger 33.
  • the flow of the various streams is otherwise substantially the same as hereinabove described and the temperature and pressure conditions remain the same.
  • the nitrogen and oxygen rectification products efiect removal of the carbon dioxide and frost, it any, deposited in the paths through which the air had passed during the preceding step of the process.
  • a process for producing oxygen by the liquefaction and rectification of air which comprises passing a stream of air through a path in a heat exchange zone, passing a stream of nitrogen rectification product through another path in said heat exchange zone in heat exchange relation with the air passing therethrough, thereby cooling the air to a temperature close to its condentation point at the pressure prevailing in said heat exchange zone and effecting substantially complete removal of carbon dioxide from the air in its passage through said heat exchange zone, warming a minor portion of the thus chilled air to a temperature such that upon subsequent expansion substantially none of the expanded air is liquefied, expanding the warmed portion of the air to produce refrigeration in amount sufficlent to compensate for cold losses resulting from the difference in enthalpy between the incoming air and the outgoing products of rectification and for heat leak; into the process, pas ing the remainder of the air at said temperature close to its condensation point to a rectification zone, maintaining the temperature difference between the temperature of the air leaving and the tem perature of the nitrogen rectification product entering said zone so that it falls
  • a process for producing oxygen by the liquefaction and rectification of air which comprises passing a stream of air through a path in a heat exchange zone, passing a stream of nitrogen rectification product through another path in said heat exchange zone in heat exchange relation with the air passing therethrough, thereby cooling the air to a temperature close to its condensation point at the pressure prevailing in said heat exchange zone and effecting substantially complete removal of carbon dioxide from the air passing through said zone, warming a minor portion of the thus chilled air by passage through said heat exchange zone, mixing said minor portion with another minor portion of the air leaving said zone to produce an air mixture having a temperature such that upon expansion substantially no liquid air is formed, passing the remainder oi the air leaving said heat exchange zone to the high pressure stage of a, rectification system.
  • a process for producing oxygen by the liquefaction and rectification of air which comprises passing a stream of air through a path in a heat exchange zone, passing a stream of nitrogen rectification product through another path in said heat exchange zone in heat exchange relation with the air passing thcrethrough, thereby cooling the air to a temperature close to its condensation point at the pressure prevailing in said heat exchange zone and effecting substantially complete removal of carbon dioxide from the air passing through said zone, warming a minor portion of the thus chilled air by passage of at least a portion thereof through a portion only of said heat exchange zone thereby heating said minor portion to a temperature such that upon subsequent expansion substantially no liquid air is formed, passing the remainder of the air leaving said heat exchange zone to the high pressure stage of a rectification system, expanding the warmed air to produce refrigeration in amount sufficient to compensate for cold losses due to the difference in enthalpy between the incoming air and the outgoing products of rectification and for heat leaks into the process, introducing the expanded air into the low pressure stage of said rectification system, maintaining the temperature difference between
  • a process for producing oxygen by the liquefaction and rectification of air which comprises passing two streams of air through two paths in a first and second heat exchange zone, passing streams of nitrogen and oxygen rectification products through other paths in said heat exchange zones in heat exchange relation with the air passing therethrough, thereby cooling the air to a temperature close to its condensation point under the pressure prevailing in said heat exchange zones and effecting substantially complete removal of carbon dioxide from the air in its passage through said zones, withdrawing a minor portion of the air leaving said zones and repassing at least a portion thereof through one of said zones to warm said minor portion to a temperature such that upon subsequent expansion substantially no liquid air is formed, introducing the warmed air into an expander, expanding the warmed air to produce refrigeration in amount suiflcient to compensate for cold losses resulting from the difference in enthalpy between the incoming air and the outgoing products 01 rectification and for heat leaks into the process, introducing the expanded air into the low pressure stage of a rectification system, passing a minor portion of the nitrogen stream leaving the low pressure stage
  • a process for producing oxygen by the liquei'action and rectification of air in a two stage rectification system involving a high and a low pressure stage which comprises passing two streams of air at a pressure of from about 60 pounds to about 100 pounds through two paths in a first and second heat exchange zone, passing streams of nitrogen and oxygen rectification products through other paths in said heat exchange zones in heat exchange relation with the air passing therethrough, thereby cooling the air to a temperature close to its condensation point at the pressure prevailing in said heat exchange zones and effecting substantially complete removal of carbon dioxide from the air in its passage through said zones, withdrawing a minor portion of the air leaving said zones, repassing at least a portion of said minor portion through one of said zones to warm said minor portion to a temperature such that upon subsequent expansion substantially no liquid air is formed, introducing the warmed air into an expander, expanding the warmed air to a pressure of from about 4 pounds to about 10 pounds to produce refrigeration in amount sufi'icient to compensate for cold losses resulting from the difference in enthalpy between incoming air
  • a process for producing oxygen by the liquefaction and rectification oi air in a two stage rectification system involving a high and a low pressure stage which comprises passing a stream of air through a path in a first heat exchange zone, passing a stream of nitrogen rectification product through another path in heat exchange relation with the air in said first heat exchange zone, thereby cooling the air to a temperature close to its condensation point under the pressure prevailing in said heat exchange zone and effecting substantially complete removal of carbon dioxide from the air in its passage through said zone, withdrawing a minor portion of the air leaving said zone and repassing at least a portion thereof therethrough to warm said minor portion to a temperature such that upon subsequent expansion substantially no liquid air is formed, introducing the warmed air into an expander, expanding the warm air to produce reirigeration in amount sufilcient to compensate for cold losses resulting from the diflerence in enthalpy between the incoming air and the outgoing products of rectification and for heat leaks into the process, introducing the expanded air into the low
  • a process for producing oxygen by the liquefaction and rectification of air in a two stage rectification system involving one stage maintained at a pressure of from about 60 to about 100 pounds and a low pressure stage maintained at a pressure of from about 4 to about 10 pounds, which comprises passing a stream of air at a pressure of from about 60 to about 100 pounds and a. temperature of from about 70 to about 110 F. through a path in la first heat exchange zone, passing a' stream of nitrogen rectification product through another path in said first heat exchange zone in heat exchange relation with the air passing therethrough, thereby cooling the air to a temperature below 270 F.
  • a process for producing oxygen by the liquefaction and rectification of air in a two stage rectification system involving a high and a low pressure stage which comprises passing a stream of air through a path in a heat exchange zone, passing a stream of oxygen rectification product through another path in said heat exchange zone in heat exchange relation with the air passing therethrough, passing a minor portion of the nitrogen rectification product through said heat exchange zone, thereby warming said minor portion, mixing the warmed minor portion with the remaining major portion of the nitrogen product of rectification and introducing the resulting mixture at a temperature of from about 5' to about 10 F.
  • a process for producing oxygen by the liquefaction and rectification of air in a two stage rectification system involving a high and a low pressure stage which comprises passing a stream of air through a path in a heat exchange zone, passing from the low pressure stage of the rectification system a stream of oxygen through another path in said heat exchange zone in heat exchange relation with the air passing therethrough, withdrawing a minor portion of the air stream leaving said heat exchange zone and repassing it through said heat exchange zone to warm the said minor portion of the air, passing the thus warmed air in indirect heat exchange relation with a minor portion of the nitrogen withdrawn from the low pressure stage of the rectification system thereby warming this minor portion of the nitrogen and cooling said minor portion of the air to a temperature such that upon subsequent expansion substantially none of the air is liquefied, mixing the warmed minor portion of the nitrogen with the remaining major portion of the nitrogen withdrawn from the low pressure stage of the rectification system to produce a mixture having a temperature of from about 5 to about 10 F.
  • a process for producing o ygen by the liquefaction and rectification of air in a two stage rectification system involving a high and a low pressure stage which comprises passing a stream of air through a path in a heat exchange zone, passing from the low pressure stage of the rectitlcation system a stream of oxygen through another path in said heat exchange zone in heat exchange relation with the air passing therethrough, withdrawing a minor portion of the air stream leaving said heat exchange zone, withdrawing a minor portion of the nitrogen stream leaving the low pressure stage of said rectification system, warming one of said minor streams by passage through said heat exchange zone, passing the thus warmed stream in heat exchange relation with the other minor stream to warm it thereby producing warmed minor streams of air and nitrogen, said warmed minor air stream being at a temperature such that upon subsequent expansion substantially no liquid air is formed, mixing the warmed minor nitrogen stream with the remaining major portion of the nitrogen withdrawn from the low pressure stage of the rectification system to produce a nitrogen stream at a temperature of from about to about F.
  • a process for producing oxygen by the liquefaction and rectification of air which comprises passing a stream of rectification product through a path in a heat exchange zone, passing a stream of air through another path in said heat exchange zone to recover the cold content of the rectification product stream and thereby cool the air to a temperature close to its condensation point at the pressure prevailing in said heat exchange zone and effect substantially complete removal of carbon dioxide from the air in its passage through said heat exchange zone, warming a portion of the thus chilled air to a temperature such that upon subsequent expansion substantially none of the expanded air is liquefied, expanding the warmed portion of the air to produce refrigeration in amount suflicient to compensate for cold losses resulting from the difference in enthalpy between the incoming air and the outgoing products of rectification and for heat leaks into the process, passing the remainder of the air at said temperature close to its condensation point to a rectification zone, maintaining the temperature difference between the temperature of the air leaving and the temperature of the rectification product entering said zone so that it falls within the range of about 5 to about
  • a process for producing oxygen by the liquefaction and rectification of air which comprises passing a stream of nitrogen rectification product through a path in a heat exchange zone, passing a stream of air through another path in said heat exchange zone to recover the cold content of the nitrogen rectification product and thereby cool the air to a temperature close to its condensation point at the pressure prevailing in said heat exchange zone and effect substantially complete removal of carbon dioxide from the air passing through said zone, warming a minor portion of the thus chilled air by passage of at least a portion thereof through said heat exchange zone thereby heating said minor portion to a temperature such that upon subsequent expansion substantially no liquid air is formed, expanding the warmed air to produce refrigeration in amount sufficient to compensate for cold losses resulting from the difference in enthalpy between the incoming air and the outgoing prodnets of rectification and for heat leaks into the process, introducing the expanded air into the low pressure stage of a rectification system, maintaining the temperature difference between the temperature of the air leaving and the temperature of the nitrogen rectification product 25 26 entering said zone so that it

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Cited By (23)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2622416A (en) * 1949-03-30 1952-12-23 Standard Oil Dev Co Separation of low boiling gas mixtures
US2663168A (en) * 1949-05-23 1953-12-22 Air Prod Inc Method for defrosting gas separation systems
US2663170A (en) * 1945-05-10 1953-12-22 American Locomotive Co Heat exchanger
US2667043A (en) * 1950-04-22 1954-01-26 Joy Mfg Co Method and apparatus for the separation of gases
US2668425A (en) * 1951-08-25 1954-02-09 Kellogg M W Co Removing impurities from a gas liquefaction system with aid of extraneous gas stream
US2673456A (en) * 1949-06-16 1954-03-30 Standard Oil Dev Co Separation of low boiling gas mixtures
US2675889A (en) * 1949-04-01 1954-04-20 Schweizerhall Saeurefab Method for processing crude gases obtained on halogenating metallic ores
US2682162A (en) * 1951-02-17 1954-06-29 Langer Julian Separation of gases into two components by distillation
US2763137A (en) * 1951-07-10 1956-09-18 Joy Mfg Co Apparatus for and method of separating gases
US2777299A (en) * 1953-04-13 1957-01-15 Kellogg M W Co Separating gas mixtures
US2802349A (en) * 1951-08-25 1957-08-13 Kellogg M W Co Removing impurities from a gas liquefaction system with aid of extraneous gas stream
US2817215A (en) * 1952-07-28 1957-12-24 Nat Res Dev Liquefaction and distillation of gaseous mixtures
US2838918A (en) * 1953-08-12 1958-06-17 Linde Eismasch Ag Process for the partial liquefaction of gas mixture by means of pressure and intense cooling
US2840994A (en) * 1947-01-31 1958-07-01 Kellogg M W Co Method of separating gaseous mixtures
US2863295A (en) * 1955-07-19 1958-12-09 Herrick L Johnston Inc Process for separating a gas mixture into its components
US2904966A (en) * 1955-07-28 1959-09-22 Joy Mfg Co Apparatus for and method of separating gases
US2917902A (en) * 1954-08-06 1959-12-22 Commissariat Energie Atomique Gas purification process
US2932174A (en) * 1954-08-19 1960-04-12 Air Prod Inc Apparatus and method for fractionation of gas
US2956410A (en) * 1956-10-05 1960-10-18 Kellogg M W Co Gas separation
US3059438A (en) * 1957-05-13 1962-10-23 Air Prod & Chem Apparatus and method for fractionation of gas
US3246478A (en) * 1963-04-08 1966-04-19 Union Carbide Corp Process and apparatus for separating low-boiling gas mixtures
US20150000523A1 (en) * 2012-08-24 2015-01-01 The Boeing Company Aircraft fuel tank flammability reduction methods and systems
US20220170701A1 (en) * 2019-02-25 2022-06-02 L'Air Liquide, Société Anonyme pour l'Etude et l'Exploitation des Procédés Georges Claude Apparatus for exchanging heat and material

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2460859A (en) * 1944-05-01 1949-02-08 Kellogg M W Co Method of gas separation including impurity removing steps

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2460859A (en) * 1944-05-01 1949-02-08 Kellogg M W Co Method of gas separation including impurity removing steps

Cited By (24)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2663170A (en) * 1945-05-10 1953-12-22 American Locomotive Co Heat exchanger
US2840994A (en) * 1947-01-31 1958-07-01 Kellogg M W Co Method of separating gaseous mixtures
US2622416A (en) * 1949-03-30 1952-12-23 Standard Oil Dev Co Separation of low boiling gas mixtures
US2675889A (en) * 1949-04-01 1954-04-20 Schweizerhall Saeurefab Method for processing crude gases obtained on halogenating metallic ores
US2663168A (en) * 1949-05-23 1953-12-22 Air Prod Inc Method for defrosting gas separation systems
US2673456A (en) * 1949-06-16 1954-03-30 Standard Oil Dev Co Separation of low boiling gas mixtures
US2667043A (en) * 1950-04-22 1954-01-26 Joy Mfg Co Method and apparatus for the separation of gases
US2682162A (en) * 1951-02-17 1954-06-29 Langer Julian Separation of gases into two components by distillation
US2763137A (en) * 1951-07-10 1956-09-18 Joy Mfg Co Apparatus for and method of separating gases
US2802349A (en) * 1951-08-25 1957-08-13 Kellogg M W Co Removing impurities from a gas liquefaction system with aid of extraneous gas stream
US2668425A (en) * 1951-08-25 1954-02-09 Kellogg M W Co Removing impurities from a gas liquefaction system with aid of extraneous gas stream
US2817215A (en) * 1952-07-28 1957-12-24 Nat Res Dev Liquefaction and distillation of gaseous mixtures
US2777299A (en) * 1953-04-13 1957-01-15 Kellogg M W Co Separating gas mixtures
US2838918A (en) * 1953-08-12 1958-06-17 Linde Eismasch Ag Process for the partial liquefaction of gas mixture by means of pressure and intense cooling
US2917902A (en) * 1954-08-06 1959-12-22 Commissariat Energie Atomique Gas purification process
US2932174A (en) * 1954-08-19 1960-04-12 Air Prod Inc Apparatus and method for fractionation of gas
US2863295A (en) * 1955-07-19 1958-12-09 Herrick L Johnston Inc Process for separating a gas mixture into its components
US2904966A (en) * 1955-07-28 1959-09-22 Joy Mfg Co Apparatus for and method of separating gases
US2956410A (en) * 1956-10-05 1960-10-18 Kellogg M W Co Gas separation
US3059438A (en) * 1957-05-13 1962-10-23 Air Prod & Chem Apparatus and method for fractionation of gas
US3246478A (en) * 1963-04-08 1966-04-19 Union Carbide Corp Process and apparatus for separating low-boiling gas mixtures
US20150000523A1 (en) * 2012-08-24 2015-01-01 The Boeing Company Aircraft fuel tank flammability reduction methods and systems
US9327243B2 (en) * 2012-08-24 2016-05-03 The Boeing Company Aircraft fuel tank flammability reduction methods and systems
US20220170701A1 (en) * 2019-02-25 2022-06-02 L'Air Liquide, Société Anonyme pour l'Etude et l'Exploitation des Procédés Georges Claude Apparatus for exchanging heat and material

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