Classifications

• • 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
  • F25J3/04151—Purification and (pre-)cooling of the feed air; recuperative heat-exchange with product streams
  • F25J3/04163—Hot end purification of the feed air
  • F25J3/04169—Hot end purification of the feed air by adsorption of the impurities
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/02—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography
  • B01D53/04—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography with stationary adsorbents
  • B01D53/0407—Constructional details of adsorbing systems
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/02—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography
  • B01D53/04—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography with stationary adsorbents
  • B01D53/0462—Temperature swing adsorption
• • 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
  • F25J3/04763—Start-up or control of the process; Details of the apparatus used
  • F25J3/04769—Operation, control and regulation of the process; Instrumentation within the process
  • F25J3/04775—Air purification and pre-cooling
• • 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
  • F25J3/04763—Start-up or control of the process; Details of the apparatus used
  • F25J3/04866—Construction and layout of air fractionation equipments, e.g. valves, machines
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2257/00—Components to be removed
  • B01D2257/50—Carbon oxides
  • B01D2257/504—Carbon dioxide
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2258/00—Sources of waste gases
  • B01D2258/06—Polluted air
• • 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
  • F25J2205/00—Processes or apparatus using other separation and/or other processing means
  • F25J2205/60—Processes or apparatus using other separation and/or other processing means using adsorption on solid adsorbents, e.g. by temperature-swing adsorption [TSA] at the hot or cold end
• • 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
  • F25J2290/00—Other details not covered by groups F25J2200/00 - F25J2280/00
  • F25J2290/12—Particular process parameters like pressure, temperature, ratios
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02C—CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]
  • Y02C20/00—Capture or disposal of greenhouse gases
  • Y02C20/40—Capture or disposal of greenhouse gases of CO2

Definitions

• the present invention relates to an installation for separating gases from air and to the process for separating gases from air using this installation. More precisely, it is a question of purifying the atmospheric air before separation of said air by cryogenic distillation.
• atmospheric air contains compounds which must be eliminated before its introduction into the heat exchangers of the cold box of an air separation unit, in particular water vapor (H20), carbon dioxide ( C02), nitrogen oxides and hydrocarbons.
• a TSA air purification process cycle comprises the following steps: - Air purification at super-atmospheric pressure and at ambient temperature, possibly around 5 to 10 ° C when using refrigeration means upstream of the unit
• the air pre-treatment plants comprise two adsorbers, operating alternately, that is to say that one of the adsorbers is in the production phase while the other is in the regeneration phase.
• Additional steps to those described above can be added, such as a step of paralleling the two adsorbers, of varying duration, that is to say from a few seconds to several minutes or else a waiting step. without circulation of fluids through the adsorbent, for example at the end of the regeneration step.
• the purification unit is very generally installed after compression, that is to say at a pressure greater than 3 bar abs, frequently at a pressure greater than 4.5 bar abs. This pressure actually depends on the cryogenic cycle selected for the separation of the air.
• the cycle most used is the "double column” cycle (conventional dual column cycle) in which the air is compressed to a single pressure which corresponds, except for pressure drops, to the operating pressure of the so-called medium pressure column, that is to say, very generally between 4.5 and 6 bar abs.
• FIG. 1 shows schematically in Figure 1, such an arrangement results in large dead volumes on either side of the adsorbent volume.
• the diagrams la, b and c respectively represent cylindrical adsorbers with a vertical and horizontal axis and a radial adsorber.
• the adsorbent volumes when used in thin films are only a fraction of the total internal volume of the adsorber, typically less than 50%. This fraction tends to decrease when the size of the adsorbers is increased. Some of these dead volumes are necessary to ensure a good distribution of air and regeneration gas through the adsorbent volume.
• a very thorough purification is sought in the various impurities, in particular for hydrocarbons, especially for propane, and nitrogen oxides, generally well below one.
• the adsorbent in order to avoid any bypass of air which would pollute the production before the end of the purification step.
• the drop in the adsorption pressure of MP to atmospheric pressure has a double, if not triple, negative impact.
• the quantity adsorbed is appreciably lower, this is in particular true for CO 2, traces of hydrocarbons and nitrogen oxides.
• the quantity of water to be stopped in the atmospheric air is very appreciably greater than that of the air MP.
• a large part of the water is effectively eliminated in liquid form at the outlet of the final refrigerant of the air compressor in the MP solution. This leads to a consequent increase in the volume of desiccant.
• the adsorption of this water also has the effect of heating the air circulating through the adsorbent, again reducing the adsorption capacity of CO 2 and other impurities.
• Hybrid solutions have therefore also been proposed with partial purification at atmospheric pressure followed by final purification at medium pressure. Purification final size is small compared to a conventional solution but the fact of having to implement two units compensates for the gains that could be expected from such a reduction.
• a solution of the present invention is an air gas separation installation comprising in the direction of circulation of the air flow:
• the adsorption unit comprising at least two adsorbers A1 and A2 each having a parallelepiped shaped envelope arranged horizontally and comprising:
• L will denote the length of the adsorber A, H its height and I its width.
• the section of the adsorbent mass also has a length L and a height H.
• the choice of the pressure PI is fundamental in the context of the invention. This pressure must be low enough to allow low pressure technology for the adsorbers, that is to say in practice adsorber envelopes with flat surfaces and no longer cylindrical envelopes, but also be significantly greater than atmospheric pressure for limit the negative effects listed above. A pressure of 1.5 bar abs for example makes it possible to use parallelepipedal adsorbers with
• the purification at 1.5 bar abs remains significantly more voluminous than a purification in MP, at 3 or 4 bar abs, but also much more efficient than a purification at atmospheric pressure.
• the use of low pressure technology for the envelope can then tip the scales in favor of the solution according to the invention.
• the passage of the adsorbent masses is carried out in opposite directions.
• fixed beds is meant here that the adsorbent, whether in the form of particles (beads, sticks, granules, platelets, etc.) or of structured adsorbent such as, for example, a monolith, is immobile in an envelope itself. even motionless. This is to exclude any solution where the adsorbent is mobile and in particular any rotary system of wheel or barrel type (process in which it is the envelopes containing the adsorbent which are mobile).
• the parallelepipedal shape of the envelope of adsorbers A and B allows dense and homogeneous filling of each adsorber without having to use a complex filling system.
• the installation according to the invention may have one or more of the characteristics below:
• said installation comprises between the compression means C and the unit of
• cryogenic distillation D a single adsorption unit.
• the second volume V2 and the third volume V3 each comprise at least two adjacent sub-volumes comprising different adsorbents; with all the adsorbents arranged symmetrically with respect to the median plane of the adsorber.
• the first volume VI, the second volume V2 and the third volume V3 have vertical walls fixed in a sealed manner to the upper wall and to the lower wall of the casing of the adsorber.
• the internal part has a solid lower bottom and / or a solid upper bottom and the first volume VI
• the second volume V2 and the third volume V3 have vertical walls fixed in a sealed manner to the upper wall of the casing of the adsorber or to the solid upper base and to the lower wall of the casing of the adsorber or to the solid lower base
• the set of volumes comprises, between the lower wall of the casing of the adsorber and the solid lower base, a space in fluid communication with the volumes V4 and V5.
• the set of volumes comprises, between the upper wall of the casing of the adsorber and the solid upper bottom, a space in fluid communication with the volumes V4 and V5.
• the first volume VI, the second volume V2 and the third volume V3 have vertical walls fixed in a leaktight manner to at least one side wall of the casing of the adsorber.
• the first volume VI, the second volume V2 and the third volume V3 have vertical walls attached in a sealed manner to at least one solid plate parallel to a side wall of the casing of the adsorber.
• the set of volumes comprises, between the solid plate and a side wall of the casing of the adsorber, a space in fluid communication with the volumes V4 and V5.
• the second volume V2 and the third volume V3 comprise over the entire length of their upper end a system intended to prevent potential local pollution of the purified air.
• the first volume VI and the two volumes V4 and V5 have means making it possible to introduce and extract the various fluids circulating in the adsorber; these means for introducing and extracting fluids are preferably located on the same face of the parallelepipedal casing of the adsorber.
• the present invention also relates to a process for separating gases from air from an air flow containing at least one impurity chosen from water vapor, carbon dioxide, nitrogen oxides and hydrocarbons, using an installation as defined above and comprising the following successive stages: a) compression (1) of the air flow to a pressure PI of between 1.15 bar abs and 2 bar abs,
• step b) carried out at pressure PI.
• the method according to the invention may have one or more of the following characteristics:
• the pressure PI is between 1.15 bar abs and 1.5 bar abs, preferably between 1.20 bar abs and 1.30 bar abs.
• the method implements an installation comprising a set of
• step b) the air flow is introduced into the two volumes V4 and V5 and the purified air flow is withdrawn from the volume VI.
• the method implements an installation comprising a set of
• step b) the air flow is introduced into the space in fluid communication with the volumes V4 and V5 and the purified air flow is withdrawn from the volume VI.
• the method implements an installation comprising a set of
• the method implements an installation comprising a set of
• FIG. 2 shows schematically the hot part of the air separation unit.
• the atmospheric air 10 containing the various pollutants to be eliminated is compressed by means of the compressor C to the pressure PI, of the order of 1.5 bar abs, and this compressed air 11 is introduced into one of the adsorbers of the TSA (A1 or A2).
• this purified air 12 is sent to the downstream part of the unit which comprises in particular the cryogenic fractionation unit D.
• the regeneration gas 14 comes from this fractionation unit. It is generally impure nitrogen (that is to say containing argon and oxygen) at low pressure, close to atmospheric pressure.
• This gas - or a fraction of this gas - is heated using one or more heat exchangers (steam, electric, heat recovery from other fluids, etc.) during the heating step and then serves to cool the adsorber.
• the production 13, generally of impure oxygen (90-98%) in the case which interests us, is directed to a downstream unit not shown.
• the adsorbent whether in the form of particles (beads, sticks, granules, platelets, etc.) or of structured adsorbent such as, for example, a monolith, is immobile in an envelope itself. even motionless. This is to exclude any solution where the adsorbent is mobile and in particular any rotary system of wheel or barrel type (process in which it is the envelopes containing the adsorbent which are mobile).
• Another essential point according to the invention is the fact that the fluids circulate horizontally through the adsorbent mass.
• the latter can thus be maintained between two vertical walls porous to gas for which the tolerances on the spacing can be very low. It is thus possible to obtain very thin and very homogeneous bed thicknesses. As already indicated, it is practically impossible to achieve this level of precision with a flat adsorbent bed having a large free surface.
• the gas circulation in the entry / exit zones can be either vertical, horizontal, or even more complex with for example several entry points ... In all cases, after distribution, it is necessarily horizontal through the adsorbent layers. Due to the design of the adsorber, there is complete decoupling between the direction of flow in the free volumes and through the adsorbent mass.
• FIG. 3 illustrates an example of an arrangement of the set of volumes used in the installation according to the invention.
• the outer envelope of the adsorber 1 has been shown in thin lines while the internal part of the set of volumes (internal part) 2, arbitrarily, in thick lines.
• the envelope of the adsorber has been shown in thin lines while the internal part of the set of volumes (internal part) 2, arbitrarily, in thick lines.
• the envelope of the adsorber has been shown in thin lines while the internal part of the set of volumes (internal part) 2, arbitrarily, in thick lines.
• the envelope of the adsorber has been shown in thin lines while the internal part of the set of volumes (internal part) 2, arbitrarily, in thick lines.
• essentially the shape of a parallelepiped By “essentially the shape of a parallelepiped”, it is meant that the envelope of the adsorber and the internal part have in practice their six plane faces and have the appearance of a parallelepiped with faces at right angles but that 'there may be reinforcements, locally at least one internal or external insulating layer, and obviously the pipes or boxes for introducing and withdrawing the air and the regeneration gas.
• the absorber being placed flat on the ground in its operating position, we call L its great length, I its width and H its height. In the context of the invention, it does not matter whether they are external or internal dimensions.
• each of the parallelepipeds implemented by its 3 dimensions, namely H * L * I for the outer envelope of the adsorber and H '* L' * l for the internal part.
• the horizontal faces, floor and ceiling, are therefore identified by their dimensions L * l and L '* l' (reference 3 for example).
• the larger vertical faces are respectively marked H * L and H '* L' (reference 4 for example).
• H '* L' are porous to fluids (reference 5 for example).
• the other vertical faces of smaller dimension are then denoted H * l and H '* l' (reference 6 for example).
• the parallelepiped H '* L' * the constituting the internal part is itself divided into 3 sub-volumes, all of parallelepipedal shape.
• the central volume VI 7 is a free volume intended for the circulation of fluids.
• On either side of VI are the adsorbent masses housed in the 2 parallelepipeds V2 and V3 8 and 9.
• the internal part is symmetrical with respect to its vertical median plane which is shown schematically to the right of the sketch of the adsorber and marked 10. This median plane 10 is also the median plane of the envelope of the adsorber. It is therefore the adsorber as a whole which has a plane of symmetry 10.
• Each of the adsorbent masses will thus treat 50% of the air flow and be regenerated by 50% of the flow of regeneration gas.
• FIG. 3 is therefore only a non-limiting example of the possible configuration of the adsorber according to the invention chosen to explain the principle of embodiment.
• the different adsorbents are separated by vertical walls (H '* L') porous to the fluids which hold them and prevent their mixing. Note, however, that it is possible to set up the different
• adsorbents with a movable wall which is gradually lifted during filling and which is, depending on the case, removed or left in place at the end.
• a first adsorbent intended to remove the vast majority of water and possibly part of the CO 2 (activated alumina, silica gel, doped alumina, etc.) and a second adsorbent intended for removing the remaining CO 2, nitrogen oxides and certain hydrocarbons (X zeolites, preferably exchanged particularly with calcium and / or barium). It is equally possible to use a single bed (doped alumina, zeolite X) or 3 successive beds (for example alumina, zeolite X, exchanged zeolite).
• the adsorber is made in such a way that the vertical walls (H '* L') relating to the adsorbent volumes are fixed, at the top and in bottom, sealingly respectively to the upper wall and to the lower wall of the casing of the adsorber.
• This configuration is simple and brings rigidity to the assembly, but it is then necessary to check whether the operating conditions do not lead to excessive mechanical stresses. This will depend essentially on the materials used, on the type of fixing between walls and on the temperature used during the regeneration.
• the latter is a function of the adsorbents used, the available regeneration flow rate and the residual level of impurities in the adsorbent selected for the sizing.
• a regeneration temperature 60 to 90 ° C for example, such a configuration may be possible. It will be less easy to implement with temperatures of 150 to 250 ° C.
• the adsorber is made such that the vertical walls (H '* L') of the adsorbent volumes are sealed at the top to the upper wall of the casing of the. adsorber and at the bottom to a solid bottom - or floor - going from the outer wall of one adsorbent volume to the outer wall of the other volume as shown in section 4. b.
• the vertical walls (H '* L') of the adsorbent volumes are tightly fixed at the top and bottom to solid bottoms - respectively ceiling and floor - extending from the wall. external from one adsorbent volume to the outer wall of the other volume and down to the lower wall of the adsorber casing.
• the mechanical strength of the internal part in the casing can be improved by supports, for example in the lower part, or suspension systems, for example in the upper part.
• These holding means may have a certain flexibility to accompany the possible movements linked to the thermal expansions and contractions which have been mentioned above.
• Said means may preferably be punctual or, at least, discontinuous and not prevent the passage of fluids from one zone to the other.
• different configurations exist as to the side walls (H '* G) of the internal part.
• the lateral ends of the vertical walls of the adsorbent volumes are fixed over their entire height (H '), in a sealed manner, to the lateral walls (1-1 * 1) of the casing. of the adsorber.
• the lateral ends of the vertical walls of the adsorbent volumes are fixed over their entire height (H '), in a sealed manner, to a solid plate (H' * G).
• FIG. 5 A series of longitudinal sections are shown schematically in FIG. 5 [Fig. 5].
• the internal part represented arbitrarily in thick lines, is supposed to be fixed to the envelope by its upper part and to have its own floor on the other hand.
• Section 5a shows an internal part contiguous to the casing by its two lateral sides, 5.b by one side, the other being closed by a flat bottom and 5.c, an internal part having two own funds.
• each solid plate fixed to the internal part and the adjacent side wall of the casing of the adsorber forming an additional free volume in fluid communication with the 2 lateral free volumes (V4 and V5) and participating to form the free volume of the adsorber.
• the volumes V2 and V3 containing the adsorbent mass comprise over the entire length of their upper end a system intended to avoid the potential local pollution of the purified air linked to a bypass or to a local overflow or to a regeneration fault.
• the bypass can for its part have its origin in the settling of the adsorbent.
• At least one, and preferably all of the adsorbents used in the process will be in the form of particles.
• the method according to the invention will be such that on the one hand the central volume VI of the internal part and on the other hand the free volume of the envelope have means allowing to introduce and extract the various fluids circulating in the adsorber (air to be purified, treated air intended for the cryogenic separation unit, regeneration gas obtained from this same unit, very generally low pressure nitrogen).
• the arrangement of the internal part in the casing with its possible flat bottoms, and the arrangement of the means making it possible to introduce and extract the different fluids circulating in the adsorber requires that the circulation of said fluids between the inlet and outlet of said adsorber only takes place through the adsorbent masses, and in a horizontal manner.
• the air to be treated enters via the volumes V4 and V5 and the purified air leaves via the volumes VI and consequently, the regeneration gas enters via the volume VI and leaves via the volumes V4 and V5.
• the advantage of this arrangement comes from the TSA process as it is currently implemented at least in air purification units upstream of cryogenic separation units. Without wishing to go into details here, it should be known that in this type of unit, it is usual during regeneration to enter only the amount of heat strictly necessary for the desorption of impurities so that the heat front does not come out of the adsorbent. Reference may for example be made in this regard to document EP 1 080 773 for more complete explanations on the regulation of the heating time.
• the central volume VI of the internal part comprises a filter making it possible to treat the purified air before directing it towards the separation unit cryogenic.
• This filter removes any dust generated by the adsorbent (s).
• This filter will preferably be self-cleaning, that is to say that it will be crossed against the current by the regeneration gas which will take off any dust that may have been stopped during the previous step. A purge then generally exists at a low point making it possible to periodically remove said dust.
• This filter can be achieved in many ways. Returning to the arrangement of Figure 5.B, there is shown in Figure 6 [Fig. 6] some of these possibilities. These are sections at the level of the median plane of symmetry of the adsorber.
• the reference (20) corresponds to the casing, (21) to the internal part, (22) to the outlet pipe for the purified air and the inlet for the regeneration gas, (23) to the part of this pipe which crosses in a sealed manner the free volume of the casing, (24) to the part of this tubing belonging to the internal part and (25) the filtration zone or zones.
• Tubing and filter are shown in thick lines.
• the section of the tubing can be of any shape (round, triangular, rectangular, etc.).
• A it is the tubing itself which passes through the free volume VI (26) which acts as a filter. In this zone, it is for example perforated and surrounded by a fabric allowing filtration at 50 microns. It can also be a commercial filter fixed in the extension of the tubing which then stops at its outlet in volume VI.
• the tubing, or the commercial filter may have an internal lining of the conical type to better distribute the fluids over their entire length.
• a plurality of commercial filters (25) attached to the tubing (24) are used. This can make it possible to improve the distribution of the fluids through the adsorbent masses by distributing the fluid injection points in the free volume VI.
• a high-performance fluid distribution system is associated with filtration. It will be noted that such a distribution system can be installed independently of the filtration function. They may be 2 perforated walls installed on either side of the median vertical plane, in the free volume VI and at a certain distance from the porous walls holding the adsorbent. By creating an additional pressure drop, this system can allow an almost perfect distribution of the gas in the adsorbent masses.
• the means for introducing and extracting the fluids from the volumes VI, V4 and V5 are located on the same face (1-1 * 1) of the parallelepipedal casing of the adsorber. This makes it possible to group all the entries and outlets from the adsorber to facilitate connections with equipment outside the adsorber itself (valves, exchanger, etc.).
• FIG. 7 illustrates such an implementation.
• B namely an internal part contiguous to the casing by its upper face and by one side, with a simple tubing entering the free volume VI as shown at 6.
• A We keep the same references as that of this section.
• section 7. A along the vertical median plane of the adsorber, the air to be purified arrives through the pipe 27, enters the casing of the adsorber.
• the bottom 28 of the internal part acts as a deflector and distributes the air flow in the free volume 29 between the wall of the casing and said bottom.
• FIG. 7. B is a schematic view from above and illustrates the circulation of air in the adsorber.
• the air After having circulated in the free volume 29, the air enters the 2 free volumes V4 and V5 marked 30, passes through the porous walls holding the adsorbent, then the adsorbent masses, emerges through the central porous walls, penetrates into the discharge pipe and exits the adsorber 22.
• the most conventional TSA-type purification unit comprises two identical adsorbers, one being in the production phase while the second is in the regeneration phase.
• the various flows are then directed and extracted from the adsorbers by a set of valves which allow the purification cycle to be carried out in accordance with the process implemented. All these elements are connected by pipes. Valves, pipes and other ancillary equipment such as instrumentation, connecting cables, air inlet
• valve skid a structure generally called a "valve skid”.
• the TSA type adsorption unit in its implementation comprises on either side of a central zone, 2 adsorbers conforming to the descriptions
• said central zone comprises the means of distributing or recovering the various process flows such as valves, pipes, etc., that is to say that this zone central corresponds to what has been called "valve skid".
• the 2 adsorbers and the “valve skid” of the central zone are aligned and form a single large parallelepiped of height Ht, width It and whose length, Lt, is equal to the sum of the lengths of the 2 adsorbers and that of the central zone. More precisely, it is ensured that the height Ht of this large parallelepiped is essentially equal to the height H of an adsorber and that its width It is essentially equal to the width I of an adsorber. In this way, we obtain a compact unit which can form a whole and of which the whole interest will be seen below. In figure 8 [Fig.
• the large parallelepiped 40 corresponding to the complete purification unit and comprising a first adsorber 41 as previously described with its inlets and outlets through its side face 44. Opposite is found. the second adsorber 42 produced symmetrically to the first and whose inlets and outlets are therefore effected via its lateral face referenced 45.
• the central part 43 corresponds to the “valve skid”, the role of which has been explained above.
• the central part also contains the regeneration heater.
• said central part can also house the final refrigerant of the air to be purified and a separator pot to separate and then eliminate the condensates so that all the equipment corresponding to the "purification of the air" function. air "are found in the large parallelepiped.
• the advantage of producing an air purification unit in accordance with the previous description lies in the possibility of having at least one common base for the different parts (the 2 adsorbers and the valve skid) and of being able to transport it in its entirety after for example a construction in workshop.
• the parallelepiped therefore comprising the two adsorbers and the central zone has a length of between 3 and 12 meters, a height H of between 1 and 3 meters and a width I of between 1 and 3 meters.
• the TSA may have the following additional characteristics:
• the parallelepiped comprising the two adsorbers and the central zone is contained in a structure conforming to ISO standards relating to containers and also comprising gripping systems conforming to these same ISO standards (often referred to as "ISO wedges").
• the TSA is then in a specific structure produced in the workshop, which can optionally use part of a standard ISO container.
• the advantage of complying with ISO standards is that it allows for greatly facilitated handling and transport. Any reinforcements allowing the mechanical resistance of the assembly to pressure will be contained in the standard dimensions of the containers.
• the parallelepiped comprising the two adsorbers and the central zone is contained in an ISO container.
• the structure of the container serves directly as a structure for the adsorbers and / or the central zone.
• the TSA's external structure is then a real container.
• At least one of the walls of the container (side, bottom, top wall) can serve directly as a wall for the outer casing of the adsorbers.
• Preferably, several walls of the container are used in this way.
• the materials used for the TSA can be varied. These will essentially be metallic (carbon steel, stainless steel, aluminum, etc.) and / or polymeric materials. In some areas, materials with low thermal expansion, such as INVAR, may be used. The construction will be done entirely in the workshop, only the connections of the various fluids being made on site. The adsorbents will preferably also be filled in the workshop.
• It relates to an oxygen production unit of the order of 100 t / d (tonnes / day) for which the air flow rate used is 15,000 Nm3 / h.
• the pressure PI on leaving the first compression stage is 1.3 bar abs.
• This air is cooled to 3 ° C by means of a refrigeration unit to limit the quantity of water vapor entrained towards the purification and to lower the adsorption temperature.
• This temperature is here in the lower range of the temperature levels used. It was chosen mainly because of the low value of PI. Temperatures of 5 to 8 ° C, or even more, could be adopted in particular in the event of a slightly higher PI pressure. The final choice stems from a global economic study.
• the adsorption time used is 150 minutes, leading to a cycle time of 5 hours, given that the purification unit usually comprises 2 adsorbers, one being in production while the other is regenerating. These conventional times could be reduced here.
• the cryogenic process adopted results in having a large flow of waste gas that can be used for regeneration, which could potentially shorten the usual heating and cooling times. Furthermore, the depressurization and repressurization steps are practically unnecessary given the respective production pressures (1.3 bar abs) and regeneration (1.03 bar abs).
• Production times of 120, 90, or even 60 minutes can be envisaged with air to be purified, optionally introduced at a temperature above the 3 ° C. used in this example.
• air to be purified optionally introduced at a temperature above the 3 ° C. used in this example.
• the total volume of adsorbent is of the order of 6 m3 distributed almost half between activated alumina and type X zeolite exchanged with calcium and barium, adsorbent particularly effective in stopping traces of hydrocarbons and nitrogen oxides. .
• each adsorber is in the form of a parallelepiped of length L equal to approximately 3 m, of height H equal to approximately 3 m, and of width I equal to approximately 2.00 m.
• Figure 9 shows a perspective section of said adsorber.
• V0 intended for the distribution of fluids 50 with the outlet pipe for the purified air and the regeneration gas inlet 51.
• This pipe which passes through the adsorber is open at its lower part and communicates with the filter 52.
• This filter also acts as a flow distributor.
• On either side of the filter there is the first porous wall 53 which maintains the zeolite bed.
• the zeolite bed 54 is approximately 0.25 m deep (wide). It is separated from the activated alumina by a second porous wall 55.
• the alumina bed 56 is approximately 0.25 m wide. It is held by the last porous wall 57 which separates it from the free volume of the envelope.
• the useful height of adsorbent is 2.1 m.
• An anti-pollution system 58 is provided in the upper part with a reserve of adsorbent 59 to compensate for the settlement and a series of nozzles 60 for filling the volumes of adsorbent respectively with activated alumina and with zeolite.
• the anti-pollution system adopted here is directly transposed from solutions developed for radial adsorbers. Without returning in details, we can say that it is a sheet inclined upwards 58 welded on one side to a porous wall all the way through and leaving on the other side a space of a few centimeters allowing the flow adsorbent particles.
• this purification is located upstream of a cryogenic air separation unit.
• This unit can in particular be well suited to the production of oxygen at low pressure, and in particular to impure oxygen with a content of between 90 and 98% purity.
• TSA Taking into account the size constraints which are fixed in this case in order to derive the full advantage of the principle of the invention, such a TSA will only be suitable for oxygen productions of a few hundred tonnes maximum. However, it might be economical to use several TSA modules of this type to power a larger cryogenic unit. These modules could then operate in parallel or, if desired, with a phase shift.
• the process described in this application is limited to the mentioned application, namely the separation of gases from air. Nevertheless, the principle of an adsorber of the type described here and operating at a low pressure, of the order of 1.10 to 1.5 bar abs. for example, could find other applications, in particular in the field of C02 capture.
• the installation according to the invention also makes it possible to produce units of small size, that is to say from a few tens to a few hundreds of tonnes per day of oxygen in a competitive manner.
• the compression means 1 could then be common to several units of possibly different nature (air boosted for combustion, for ventilation, etc.).

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