DE1592318A1 - Process for the extraction of oxygen and nitrogen in pure form under high pressure from air for the production and purification of a mixture of hydrogen and nitrogen at low temperature - Google Patents

Description

L ¹ AIr Liquide Soeiet * Anonyme peur 1'Exploitation des Procedis Georges Claude, 75, Quai d'Orsay,

Paris (7)

Process for obtaining τοη oxygen and nitrogen in pure Mold under high pressure from air for manufacturing and cleaning a mixture of τοη hydrogen and nitrogen at low temperature

Priority ι rom 30 »September 1966 due to the French Patent application PY 78 358

The invention relates to a method mr production of ammonia « synthesis gas in which the hydrogen is produced by cracking clay coals " Hydrogen with the help of an acidic gas, ankle " send partial transfer of carbon monoxide and removal τοη Carbon dioxide is produced, after which it is cooled and washed with the aid of liquid nitrogen in such a volume that it becomes a mixture τοη pure hydrogen and nitrogen, which is rich in oxygen Gas and nitrogen by liquefaction and rectification τοη Air at low temperature wins and at least part of the liquid nitrogen used for scrubbing the hydrogen

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by cooling a pure nitrogen stream below · 1η · Μ Pressure at least equal to that of hydrogen scrubbing in indirect heat exchange with at least part of the oxygen-rich liquid is obtained, which is separated in the rectifying cell under the lowest pressure, after iie previously at the desired pressure for cracking the hydrocarbons have been brought into the liquid phase

In the French patent 1 338 9 * 5 * ·? Applicant ▼ em 22 August 1962 a procedure of this kind is described, in which the rectification of the air in at least two colon »

in the
The heat exchange takes place under different pressures by means of a condenser-evaporator, which causes the condensates of part of the nitrogen separated at the top of the high-pressure cylinder Vassersteffes by vasification with liquid Stiokateff is necessary, compared to the sum of the energy expenditure of the devices for the air separation and Vassersteffwaschung with liquid nitrogen independently of each other.The process according to this patent specification, however, also includes a cooling of a toilet of the su serlegend air in a special Värmeaustauschleitumg with their soles ! hurried relaxation under MuAerer work and their linblaamng in a rectification column for the air under low pressure «This is to a certain extent the heat exchange device and the extraction of very pure nitrogen through made the reclamation more difficult and the control of the entire work organization more difficult *

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The task of the method according to the invention is to eliminate these deficiencies; Ea concatenates the air separation processes and hydrogen washing with flüaaigeai nitrogen and allowed with a simultaneous reduction of the energy expenditure the excessive cracking of hydrocarbons under high pressure of 70 bar or aolbat 120 to 150 bar can, and dio Vaeaerateffwaschung with liquid nitrogen under the same high pressure without prior sealing The reduction of the energy consumption basically results from the fact that the pre-seal is subject to high pressure overall on the Hydrocarbons and not partially applied to the purifying hydrogen-rich gas of high molar volume. The process is outwardly simple, since the su decomposing air under a uniform relatively low pressure remains mad as a result the control is very light. Ea goatatted finally the condensation of the Gaae exclusively by means of Turbo compressors, alao cheaper machines from oiaor saichereren Perform function ala piston compressor »

Daa Verfahrest according to the invention is _f characterized in that the whole dor for Vaesersteffwaschmng with liquid · "nitrogen and mlndoatona the main part dor for dio Luftserlegung at low temperature required refrigeration dureh Eisten traveled Stiekatoffgaakreia is gewährleiatet" represents oiaor head Rektifisierkolenne dor air diverted and What is thickened is what oia Toll mater of external work distribution aad "in second Toll verfläasigt" ad to the oiaon portion for hydrogen monitoring and to the other portion generally at least one rectifisiorsoae of the air is sent back.

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On the other hand, the invention includes the following features which are used separately or in parallel can "

a) Pure nitrogen gas of the circle is at the top of a High pressure zone of air rectification removed

b) The air rectification zone, into which the other part of the liquid nitrogen is sent back, is the high pressure zone,

c) The compression of the circulatory nitrogen takes place in a turbo compressor in two stages, and the one under outer Nitrogen that is relaxed at work is cleaned with the nitrogen that comes out of the first stage of the turbo compressor.

d) The hydrogen scrubbing takes place under a higher pressure than the critical pressure of the nitrogen.

Below is a combined example based on the drawing System for air separation and vase washing with liquid nitrogen according to the invention explained. At this The plant should first be the air separation plant and then the washing facility for hydrogen with liquid nitrogen ■ how finally the only refrigeration cycle is described which ensures the function of the two devices.

The dedusted air to be decomposed is passed through line 1 to the turbo compressor S supplied and there to a pressure of 6.6 bar \

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absolutely brought. At ι · 1η ·> output is al · in · 1η · Η not shown Vaaser cooler and then in a refrigeration machine 3 of the usual type, for example with Ua running το η liquid · «Asuaeniak in the evaporation * stage in a tube bundle of the heat exchanger 4 cooled, which brings their temperature to + 5 ° C. The condensed water is tapped in the separator 5 through valve 6. Then the air goes into the battery 7a »7b with adsorbent mass for drying and cooling acid removal, τ © η of which one is in operation in the usual way, while the other is in the process of regeneration. These adsorbent masses contain, for example, a first layer of active tenerde, which brings about the drying, while a subsequent layer of artificial zealite such as one according to French patent 1 369 377 29 April 19 © "3 and 1 4ll 793 Zeolite seized from the applicant on July 21, 1964, which causes the throats · »removal and elimination of traces of hydrocarbons, especially acetylene _f direct air to the in-operation adsorbent au and separate the other.

The dry air, freed from throat acid, then turns Line 10 sent to exchanger 11, see la heat

a ick
teff mmd nitrogen under mlherem

Pressure, «it comes from the hectic races, cools down. The air then passes through the duct 12 into the heat exchanger 13, and the heat exchange "with the" same fluid cools down until it is close to the dew point. Bamm is flamed el · dmreh Leitmmg Xk on the leather of the Eeekdrmokmelenme 15. The last "is aa upper lud · bit bucket l" tired "sater-Yerdam" fer It amsgeHlstet, who rushes with buckets of office in the MMertmkrektifikierk ·! · »* · *» § * -

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separated liquid Sauereteffβ is fed. The condensate errerdampfer delivers the sticketeff reflufl in the kolenne 15 ·

The sticketeff that rerflueses at the Kentakt dee Kendeneatere 16 and sinks into the bottom of the column is partly collected in the troughs 17, which are arranged a little below the tip of the Ko-Ieline Röarang "means of" Stiekatoffga "separated at the top of the low-pressure column 31. The Sticketeff ia valve is subcooled to the ·· ¥ EIEE 30 to about I ₉ 3 Bar abeolut entepannt and introduced at the top of the column 31 ale reflux.

On the other hand, at the top of the column 15, purer stickatoff gas with, for example, 2. ΙΟ ** ⁵ parts by volume of Sauerat deducted »which can be used for vaaching the vaeaer toffee to be cleaned. Dieaer Stiekateff is heated in exchanger 13 to -90 C and ⁹ -rerläSt it through line 20 then goes to Sr · a portion through conduit 21, exchanger 11 and conduit 23 la FICHES · tro * to the air to be separated and the other part through line 22 "Auetaueeher IQk" and line 24 in the Oegecetrea a "part of the" high pressure tick teffes de cooling circuit "" A * f dieee "eiee wire, the nitrogen" ng · about on UagebaagatOMporatur and discharged through line 25 , uzt Kda4eate »e ι« main part in the elozi Kaltekrei · and al «Vaachf ln · - • ity de · ftiekatoffa rorwendet, MLo referring to moeW beeehrlebezi are aoll.

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At the bottom of Kolonn "15 to the other feeds · oxygen-enriched liquid τοη about 35 1" off oxygen, which is filtered in a known manner in the battery 32a and 32b "it Adeorbenemassen to derive remove the last Kehl hydrogen traces. One of these masses is in operation while the other is in regeneration · The changeover of the fluid circulation · in these masses takes place through a valve clearance 33a, 33b, 34a, 3 ¹ Ib. The oxygen-enriched liquid then passes through the line 35 to the subcooling heat exchanger 36, the refrigerant of which "consists of the nitrogen gas withdrawn at the top of the low-pressure column 31". Then, the valve 37 is expanded to 1.3. Bar absolute and introduction to the middle zone of column 31

At the top of this column can be seen through line 42 from relatively impure nitrogen gas in the exchanger 29 and 36 is heated and then successively through the lines 43 and 44 goes into exchangers 13 and 11, it is released into the atmosphere submitted or to a possible point of use is sent through line 45

The liquid oxygen withdrawn in the bottom of the column JA through line 38 is split into two parts. The first part is conveyed to the condenser-evaporator 16 by the circulation pump 39 and line 4. Once or la the pipes of this capacitor has been evaporated so goes or duroh Lei · "tung kl back to the bottom of the column Jl, where he handles the Meizung. The second portion is brought to a pressure of 95 bar absolute by the pressure pump 46 and through line 47

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xu heat exchangers sent · This oxygen is initially to about -155 * 0 la exchanger 48 in countercurrent with one Tail dea Kältekroialaufatickatoffa heated below 75 bar · Then he goes through line 52 to exchanger 53 to get further on about -110 * 0 also in countercurrent with high pressure and in Gleichetrom with exhaust ticket of the tension turbine 93 Heat xtt · Finally it goes through line 56 into the exchanger 57, where he also uses high pressure catickatoff dea cooling circuit is heated to almost ambient temperature Then it is fed through line 58 to the coal waaeratoff cracking furnace, not shown sent.

The impure hydrogen coming from the cracking furnace is sent after conversion of the carbon dioxide and removal of the carbon dioxide with subsequent drying in conventional devices, not shown, through line 60 to exchanger 61, where it exchanges heat with part of the mixture of purified water and gas. The nitrogen emerging from the washing column cools to -182 ° C · Then enters the condenser 6k through line 6la, where or aich cools to -190 ° C and a partial condensation of carbon monoxide, methane and argon is necessary. Dioae are de-taped in valve 67 almost to atmospheric pressure and with the real liquid of the Vaach column Toroinigt »Then the ¥ aaaeratoff is introduced through line 68 at the bottom of the Yaach column 69 · Dieae is fed at the top with liquid Stieksteff, which comes from the aua dom refrigeration cycle. To the Zwook a Toll doa aua the most fluid level doa Kompresaora 92 under 75 bar abaolut auatretondon Stickateffa with a flow rate adjustable by valve 96 is sent into the exchanger 97,

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where he himself, in countercurrent, rait part of the mixture of purified Hydrogen and nitrogen from the scrubbing column are cooled to ~ 170 ° C, in order to then exit through line 98 Another nitrogen stream withdrawn at -170 ° C at the cold end of exchanger 82 is, after cooling in the refrigeration circuit, to be further described later, through line 84 united with him. The entire stream is introduced through line 99 into exchanger 72, where it is in heat exchange with the mixture of purified hydrogen and nitrogen from the scrubbing column experiences its cooling to -191 ° C · Then the cold nitrogen is introduced through valve 70 at the top of the column 69, where or with entrainment of the impurity oη dos Hydrogen, such as carbon oxide, methane and argon migrates downwards

The mixture of purified hydrogen and nitrogen is withdrawn from the scrubbing column 69 at about -193 ° C. In the already mentioned exchanger 72, it warms up to -188 ° and then goes through line 62 to the exchangers 61 and 97 »* ie connected in parallel and into which the mixture is introduced through lines 73a and 73. The respective flow rates can be controlled by a valve Jk , which is arranged at the warm end of the exchanger 97. After heating in these exchangers to + 25 * and exhaust through the line 63a and 63b as well as 75, the mixture receives an impregnation of pure warm nitrogen for the purpose Adjustment of their molar composition to the desired value τοη 75 % hydrogen · Finally, the Gern! Βoh is sent through line 77 to the ammeniac synthesis furnace not shown.

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The reactive liquid, which is soft on the carbon monoxide of Hethane and Argoi, which collects in the bottom of the Vaach column, is withdrawn therefrom through line 78.A first part of this is sent through line 79 and expansion valve at approximately air pressure to condenser 64, where it partially condenses the impurities of the hydrogen. The liquid thus vaporized is withdrawn through line 66. The other part of the residual liquid is also expanded to approximately air pressure in the valve 80 and combined with the liquid impurities that were separated in the condenser and are expanded in the valve 67.After the addition of the vapors coming from the cold side of the condenser 64, passes through the line 66 the whole stream successively through lines 81 and 86 into the exchangers and 87t before it evaporates and warms up to ambient temperature in countercurrent to nitrogen fractions of the cooling circuit. The remaining liquid is then drawn off through line 88.

The nitrogen cooling circuit is made of pure nitrogen gas, that has been heated in the exchangers 14, 11 and 104, is branched off from the discharge line 25 through line 27; however, a fraction can be withdrawn therefrom through line 26 and, if necessary, for a different purpose are sent «Dar rain · through line 27 withdrawn stickst "Ff" becomes "ok" mpress "rs in the two stages 90 and 92 of the door aaselut compressed to 75 bar »during the from the discharge side The relaxation turbine 93 originated and reheated Nitrogen introduced at the inlet of the second stage 92 becomes «The mm · exiting the Turaokomprassvr through line 94

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Nitrogen is then cut into three parts.

The enter part is regulated in an adjustable amount through valve 76 with the mixture of pure hydrogen and warm tea nitrogen Purified to adjust its composition to the value required for the synthesis of ammonia

The second part is in the exchanger 97 in countercurrent with the mixture of pure in an amount that can be regulated by the valve 96 Hydrogen and nitrogen are cooled to −170 ° C. and then sent through lines 98 and 99 to exchanger 72 and introduced through valve 70 at the top of the washing column 69 "

A third part goes through line 95 and becomes three in Aon exchangers 87, 57 and 104 connected in series in the counterstsom see below rust liquid of the washing stage, oxygen name Rectifying column or pure nitrogen -ren Mitteleruck from the high pressure rectifying kelenne and the stress relief turbine cooled down. The main part of the cooled in exchanger 57 Nitrogen is then sent through line 107 to turbine 93, where it is expanded to 23 bar absolute. The turbine 93 ie * * on the same shaft as the compressor 90.92 arranged, which allows the power to be given to the sound recover · The remainder of the nitrogen cooled in exchanger 57 is passed through line I09 with the cooled nitrogen τβ cleans from the exchangers 87 and 104 through lines 110 and 106 exits. The whole cleaned Gas flow goes through line 54 and is then up again -150 C in exchanger 53 in countercurrent to that in the turbine

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• Nt pressurized nitrogen and pressure age substance cooled down ·

Nitrogen emerging from exchanger 53 through line 55 at -150 ° C below 75 bar goes a first part through line 49 into exchanger k8, in front of it the newest, to -170 ° C countercurrent xu branched off pressure acid is cooled off and is then absolutely released in valve 50 to approximately 6 bar. The other Toil is passed by line 83 in don exchanger 82 to be xu ύdarin also to -170 ° C lsi Geeenstrem the rest of liquid from the scrubbing column abxukühlen · The nitrogen "is joined to part by conduction 8k" it dost pressure nitrogen by lines 98 and 99 "are sent to the top of the washing column and the other part is depressurized to 6 bar through line 85 and valve 85" and combined with the nitrogen expanded in valve 50 introduced into the high pressure air supply column 15

Ss is Ii notice that there are various modifications to the plant described above can be vergenoxeien without VOSi essence of the invention abxuweionen · In particular, the Separation of the air is carried out in a single rectifying column or in a number of rectifying colons greater than 2 In the former case, the nitrogen cooling circuit is provided only the cooling at the top of the column and the liquefaction of the nitrogen can do a part through heat exchange be carried out with the liquid oxygen from the column sump. If necessary, you can rely on it

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limit, produce impure Sauerat «ff -ran eg 70 % ^BU. The addition of nitrogen to the Vaaaerataff avaoka attitude to the fact that the ammonia synthesis process can be done in liquid form in Gaaform.

The washing of the impure oxygen can take place under one
noticeably higher pressure ala 70 bar, e.g. 120 to 150 bar. In the latter case, the supplement will
the cold generation of the stick stiffener is preferably carried out for the purpose of facilitating the exchange of heat by relaxing with external work except for
applies a lower pressure of about 5 bar «

Finally, the air can be purified and exchanged in reversible heat exchangers with less pure nitrogen
be cooled by low pressure, no matter how high the. applied washing pressure is *

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Claims (3)

1. The method for dividing ammonia by dividing it up by means of coal cracking with the aid of an oxygen-rich gas, then partially transforming the carbon dioxide and removing the carbon dioxide, then cooling it to a mixture and washing it with liquid nitrogen in the water pure "Vaaaeratoff and nitrogen obtained daa aaueratoffreiche Gaa and Stickatoff by Verflüaaigung and Rektifisierung wins τοη air at low temperature and aindeatena part dea the Waachung dea Vaaaerateffea effecting flüaaigen Stickatoff by cooling Onea pure Stickateffatroees under a pressure mindeatena equal to that of Vaaaeratoffwaachung ± m Indirect Vänaeauatauach bit at least a part of the aaueratof-rich liquid, which is separated in the low-pressure rectification zone and previously brought to the desired pressure for the hydrocarbon cracking in a liquid phase, thereby identified et that the whole cold production required for washing dea Vaaaeratoffa with liquid Saueratoff erferderlida, and Bindestena the main part of the cold, which is required for the air separation at low temperature, are supplied to a pure sticket offgaekreia, the aa head of an Luftrektifiaieraene abzegea and Terdicht Iat, where an erater AnMl of water uflerer Arbeitsaleiatung was detached and a further part, Terfltlaaigt mud aim part "ur Vaa a era t of fwaackun" ge * OOMS.0 / 1676 sends and on the other part in mlndeatena an air rectification zone is returned. 2 · The method according to claim 1, characterized in that the pure nitrogen gas of the KUhlkreiaea at the top of an air rectification column is withdrawn, which is under the highest pressure 3. The method according to claim 1, characterized in that daduroh the rectifier of the air into which the other part dea liquefied nitrogen is returned, the zone is under the highest pressure. k » Process according to claim 1, characterized in that the pure nitrogen of the coolant is compressed in two stages and that the erate part of the circulatory nitrogen content is released with external work on the pressure of the first compression stage and combined with the nitrogen emerging from this first stage · SAD 009850/1676 Blank page