Classifications

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  • 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
  • B01D53/047—Pressure swing adsorption
  • B01D53/0476—Vacuum pressure swing adsorption
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  • 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
  • B01D53/047—Pressure swing adsorption
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  • 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
  • B01D53/0446—Means for feeding or distributing gases
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  • C01B13/00—Oxygen; Ozone; Oxides or hydroxides in general
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  • C01B13/00—Oxygen; Ozone; Oxides or hydroxides in general
  • C01B13/02—Preparation of oxygen
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  • C01B13/0248—Physical processing only
  • C01B13/0259—Physical processing only by adsorption on solids
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• • B—PERFORMING OPERATIONS; TRANSPORTING
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  • B01D2257/70—Organic compounds not provided for in groups B01D2257/00 - B01D2257/602
  • B01D2257/702—Hydrocarbons
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  • B01D2257/7025—Methane
• • B—PERFORMING OPERATIONS; TRANSPORTING
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• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
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  • B01D2259/40—Further details for adsorption processes and devices
  • B01D2259/40007—Controlling pressure or temperature swing adsorption
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
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  • B01D2259/40—Further details for adsorption processes and devices
  • B01D2259/40007—Controlling pressure or temperature swing adsorption
  • B01D2259/40009—Controlling pressure or temperature swing adsorption using sensors or gas analysers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2259/00—Type of treatment
  • B01D2259/40—Further details for adsorption processes and devices
  • B01D2259/40011—Methods relating to the process cycle in pressure or temperature swing adsorption
  • B01D2259/40043—Purging
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  • B01D2259/00—Type of treatment
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  • B01D2259/403—Further details for adsorption processes and devices using three beds
• • 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
  • Y02C20/20—Capture or disposal of greenhouse gases of methane
• • 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
• • 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
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  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P20/00—Technologies relating to chemical industry
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• • 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
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P20/00—Technologies relating to chemical industry
  • Y02P20/151—Reduction of greenhouse gas [GHG] emissions, e.g. CO2
  • Y02P20/156—Methane [CH4]

Definitions

• the present invention relates to a method for adjusting a unit for separating a gas flow comprising adsorbers which follow a pressure cycle of the PSA, VSA or VPSA type.
• a gas phase adsorption process makes it possible to separate one or more molecules from a gas mixture containing them, by exploiting the difference in affinity of one or more adsorbents for the different molecules.
• An adsorbent can be, for example, a zeolite, an activated carbon, an optionally doped activated alumina, a silica gel, a carbon molecular sieve, a metallo-organic structure, an oxide or hydroxide of alkali or alkaline earth metals, or a structure porous preferably containing a substance capable of reversibly reacting with molecules, such as amines, physical solvents, metal complexing agents, metal oxides or hydroxides for example.
• adsorbent materials are in the form of particles (balls, sticks, crushed pieces, etc.) but also exist in structured form such as monoliths, wheels, contactors with parallel passages, fabrics, fibers, etc.
• the adsorbent at the end of use is regenerated in situ, that is to say that the stopped impurities are removed so that said adsorbent recovers most of its adsorption capacities and can restart a purification cycle, the essential regeneration effect being due to a rise in temperature.
• the adsorbent at the end of the production phase is regenerated by the desorption of the impurities obtained by means of a drop in their partial pressure. This pressure drop can be obtained by a drop in the total pressure and / or by flushing with a gas free or containing few impurities.
• Pressure swing adsorption processes are used both for removing traces of impurities - for example with a content of less than 1% in the feed gas - and for separating mixtures containing tens of% of different gases.
• purification for example gas drying
• separation for example production of oxygen or nitrogen from air
• Document EP 1 880 753 A2 discloses a gas separation installation in which each adsorber of a conventional installation is replaced by several adsorbers mounted in parallel and continuing the same phase of the cycle at a given time.
• Document KR 2017 0087954 A discloses a set point (quantity of gas produced by an adsorber) which may be specific to an adsorber, to compensate for different capacities (volume, adsorption performance, etc.) between two adsorbers. one unit.
• PSA denote any gas purification or separation process implementing a cyclic variation of the pressure seen by the adsorbent between a high pressure, called the adsorption pressure, and low pressure, called regeneration pressure.
• this generic name of PSA is used interchangeably to designate the following cyclic processes, to which it is also common to give more specific names according to the pressure levels involved or the time required for an adsorber to return to its initial point. (cycle time):
• VSA processes in which the adsorption takes place substantially at atmospheric pressure, preferably between 0.95 and 1.25 bar abs and the desorption pressure is less than atmospheric pressure, typically from 50 to 400 mbar abs MPSA or VPSA processes in which the adsorption takes place at a high pressure greater than atmospheric pressure, typically between 1.4 and 6 bar abs, and desorption at a low pressure below atmospheric pressure, generally between 200 and 600 mbar abs
• RPSA Rapid PSA
• URPSA Ultra Rapid PSA
• gaseous fraction recovered in a PSA process can correspond to the fraction produced at high pressure but also to the fraction extracted at low pressure when the desired constituent (s) are the most adsorbable in the mixture.
• An adsorber will therefore begin an adsorption period until it is loaded into the component (s) to be stopped at high pressure and then will be regenerated by depressurization and extraction of the adsorbed compounds before being repaired to start again. a new adsorption period.
• the adsorber has then performed a "pressure cycle" and the very principle of the PSA process is to chain these cycles one after the other; it is therefore a cyclical process.
• the time taken for an adsorber to return to its initial state is called the cycle time.
• each adsorber follows the same cycle with a time shift called phase time or more simply phase. We therefore have the relation:
• Phase time cycle time / Number of adsorbers
• This cycle therefore generally includes periods of: Production or Adsorption during which the feed gas is introduced through one of the ends of the adsorber, the most adsorbable compounds are preferentially adsorbed and the gas enriched in the less adsorbable compounds (product gas) is extracted by the second end.
• the adsorption can take place at rising pressure, at substantially constant pressure, or even at slightly falling pressure.
• HP high pressure
• Depressurization during which the adsorber which is no longer supplied with feed gas is discharged from at least one of its ends of a portion of the compounds contained in the adsorbent and the free volumes.
• Repressurization during which the adsorber is at least partially repressurized before resuming a period of adsorption. Repressurization can be done against the current and / or against the current. Dead time during which the adsorber remains in the same state. These dead times can be an integral part of the cycle, allowing the synchronization of steps between adsorbers or be part of a step which ended before the allotted time. The valves can be closed or remain unchanged depending on the characteristics of the cycle.
• a so-called Rinse stage can be added which consists of circulating in co-current in the adsorber a gas enriched in the most adsorbable constituents with the objective of removing the adsorbent and dead volumes the least adsorbable compounds.
• This Rinse step can be done at any pressure between high pressure and low pressure and generally uses a fraction of the low pressure product after compression.
• the gas extracted from the adsorber during this step can have many uses (secondary production of gas enriched in the less adsorbable constituents, repressurization, elution, fuel gas network, etc.).
• some PSA include a step of "displacement"
• Depressurization and Repressurization can be done in different ways, especially when the PSA unit comprises a plurality of absorbers (or capacitors). It is thus necessary to define elementary steps in order to describe more exactly the gas transfers which take place between adsorbers (or capacities) and with the external environment (supply circuits, product gas, low pressure gas).
• gas evacuated during the depressurization period can:
• the gas which an adsorber receives during its Repressurization can come from:
• Feed gas or Feed: Rep F The feed gas can be compressed before its introduction into the adsorber if the adsorption pressure is greater than the pressure at which it is available.
• adsorbable can be done under rising pressure, or even under pressure
• the regeneration can be carried out under vacuum, the gas being extracted by means of a pump or other equipment making it possible to perform the same function (ejector, blower, etc.); In this case, we speak rather of a pumping step. However, to be more general, the term depressurization is retained here.
• the role of balancing should be specified here. They make it possible to recover some of the least adsorbable compounds which are found in the dead volumes (intergranular space for a bed of particulate adsorbents, channels for structured adsorbents, ends of the adsorber, etc.) or which are ( weakly) adsorbed. These constituents are no longer lost in the waste, this makes it possible to increase the Extraction Yield of the weakly adsorbable gases which is defined as the fraction which is recovered in the Production relative to their quantity in the gas d 'food.
• the adsorber in depressurization successively supplying gas to various adsorbers at lower initial pressure.
• FIG. 1 illustrates the above.
• a typical pressure cycle for example of a PSA H2 has been shown.
• On the ordinate are the pressures in the adsorber and the time on the abscissa.
• This cycle comprises 9 phases and will therefore include 9 adsorbers.
• This adsorber which will henceforth be called ROI, will be supplied for 3 successive phase times with 1/3 of the flow of gas to be treated.
• the regeneration which consists first of recovering here a maximum of light gas (not very adsorbable) by means of 4 successive balances (Edi, 2, 3 and 4) which take place over time. phase 4 and 5.
• gas is continued to co-flow from the production.
• This gas (PP) will serve as an elution during the purge step.
• the remainder of pressurized gas contained in the adsorber is extracted against the current and constitutes part of the residue.
• Such a cycle comprising 4 balances corresponds to the choice of favoring the extraction efficiency of the unit to the detriment of the investment.
• each of the 9 adsorbers follows this same cycle with a lag phase time.
• the pressure cycle that we have just followed with the ROI adsorber is also an image at a given moment of the state in which each of the 9 constituent adsorbers of the PSA unit is located. For example, if the production stage does start, R02 is in its 2nd stage and R03 begins its last production stage and so on.
• phase times must be strictly identical but that there are also time constraints on the constituent sub-steps of the cycle.
• simultaneity we mean that no only these steps have the same duration but that they are placed in the same way in their respective phase time, for example at the start of a phase.
• the PSA unit will include the connections and equipment necessary to perform the flow exchanges as planned (pipes, valves, etc.) and the control / command system able to manage all these elements.
• P'3, P'2, P'1) are then the results of the flows exchanged. It could be shown that the pressures PI, P2, P3 cannot be arbitrary and that, on the contrary, there are constraints. For this reason, to obtain the desired cycle, the regulation will advantageously relate to the pressure differences at the end of the DPI, DP2, DP3, DP4 balancing and to the pressure P5, the cut-off pressure between the gas supply stage. elution and final countercurrent depressurization.
• each step of a PSA cycle is characterized by the transfer of at least a quantity of gas entering or leaving the adsorber - except for dead time steps for which by definition there is no entry or exit. These transfers should be controlled in order to carry out the cycle as planned. This is the role of the various regulations put in place as mentioned
• a physical parameter characteristic of the transfer is chosen (a pressure, a pressure difference as seen in the previous example), and a setpoint is assigned to it. or target value (bar abs, millibar, etc.) as well as the moment when this setpoint must be taken into account (at the end of the step, throughout the step, etc.), the equipment / elements to be actuate (valve, frequency converter, time delay, coefficient in a formula, etc.) to act on the quantities of flow.
• the principle of regulation then consists in comparing the measured value of the characteristic parameter with its setpoint value and in acting in such a way as to reduce this difference until the said target value is reached.
• target value or setpoint are used interchangeably, the first term rather corresponding to the process and the second to the field of regulation. Since these principles are well known, there is no need to specify further the methods of implementing such a system, which may change from one unit to another.
• the performance of a unit could be improved when an adsorber of the unit deteriorates (for example when the adsorber of one of the adsorbers is of lower quality: wear, pollution, etc.), or when the unit has at least two adsorbers with different properties (density, filling method, geometric characteristics, adsorbents with different performance).
• the subject of the invention is a method for adjusting a unit for separating a gas stream comprising N adsorbers, with N> 2, each according to an adsorption cycle of the PSA, VSA or VPSA type with a shift of a phase time, said adjustment method comprising the following steps:
• step b) at least one characteristic value of the step chosen in step a) which is chosen from among the values of the physical parameter measured in step a) or a function of these values is determined;
• the target value being a target value corresponding to the adjustment of the stage of the adsorption cycle which is presented, relative to the adsorber (i), in the form: X + Delta Xi, X being the common value for all the adsorbers and Delta Xi the correction to be made to said common value for the adsorber (i),
• the target values being pressures or pressure differences, and preferably said target values are values desired at the end of the step.
• the method according to the invention may exhibit one or more of the characteristics below:
• the target values are individualized for each adsorber
• At least one adsorber follows an adsorption cycle different from that of the other adsorbers
• step a) the step of the adsorption cycle chosen is chosen from the adsorption step, the step of balancing between adsorbers or between an adsorber and a storage capacity, a step of supplying gas d 'elution, a depressurization step with possibly pumping under vacuum, an elution step optionally under vacuum, a repressurization step or else a rinsing or displacement step; the target value (s) are determined using adsorption process simulation software taking into account the specificities of each adsorber;
• step a) a step of determining the target values of each adsorber is carried out, in particular before step a);
• the target values are periodically reassessed.
• target values are determined, by calculation or experimentally, with the help of optimum search software in a multivariate process.
• At least one adsorber can cycle
• the target values are determined using an adsorption process simulation software taking into account the specificities of each adsorber
• Target values are determined using a campaign
• Target values are determined by calculation or experimentally with the aid of optimum search software in multivariate methods.
• target values which optimize the process and are therefore the set points for the regulation (as already explained, one or the other expression is used here indifferently in the text, target value rather referring to the process and set point to regulation) will generally not all be differentiated by adsorber.
• the invention will be described in more detail with the aid of [FIG. 2].
• We are interested in the supply of elution gas (or Purge Providing) by an adsorber A to an adsorber B in the elution step and then conversely, in the supply of elution gas by the adsorber B to adsorber A in turn in the elution step.
• the flowing fluid is generally a gas rich in poorly adsorbable constituents which will aid in the desorption of the most adsorbable compounds. For example, it will essentially be hydrogen in the case of a PSA H2 or oxygen in the case of a VSA or VPSA 02.
• the adsorber A will supply the gas in question by decompression to at a final pressure Pf of 3 bar abs, the adsorber B for its part being at a pressure close to atmospheric pressure.
• the flow control device is valve 1
• the detection device is pressure sensor 3 for adsorber A and 4 for adsorber B.
• the control / command unit bears the reference 2.
• the various dotted lines schematize the connections between equipment and control unit. The roles of adsorbers A and B will then be reversed but, in the current regulation principle, the final target value will naturally be Pf equal to 3 bar abs. In practice, it is common to the 2 adsorbers and more generally to the N adsorbers which are supposed to follow the same pressure cycle.
• N target values Pf (i) two and more generally N target values Pf (i) will be defined, at least one of which will be different from the others to come within the scope of the invention.
• Pf (A) 3 bar abs
• Pf (B) 2.9 bar abs.
• the method according to the invention relates to an adsorption step.
• adsorption step Depending on the cycles that are implemented, one may want to fix the end of the adsorption step on a high pressure in the case of adsorption at rising pressure for example, over a period,
• balancing can be complete, that is to say that at the end of the stage the pressure of the adsorber which has depressurized is almost equal to the pressure of the adsorber which s 'is repressurized.
• the term "quasi" means that there remains a small pressure difference between adsorbers, say 25 mbar.
• a depressurization step This step generally follows the step above and the final pressure may be the pressure of the site waste network.
• the pressure of said network fluctuates, it is customary to maintain a pressure higher than that of the network to avoid destabilizing the PSA.
• the setpoint of this pressure can then be individualized by adsorber if there is any interest therein.
• the implementation of the principle of the invention may result in modifying the way in which the target values are generally introduced as set points for the regulation. Taking the example of the successive depressurizations of a PSA, it can be said in a simplified manner that currently the target values corresponding to the end of the stage are given in a table to which the control device has access. For example, in the case of the cycle shown in Figure 1, we could enter the corresponding data in a table like the one below:
• the first column defines the parameter in question, for example the pressure difference between adsorbers at the end of the first balancing (DPl), the second the units, the Beme the target value (we aim for 15 mbar at the end of step for the first balancing), the 4th and 5th correspond respectively to an alarm threshold and a tripping threshold (or any other action) because exceeding these thresholds means that there is a problem with the driving the unit.
• these thresholds are shown as deviation from the target value in the table.
• the target value is B bar
• an alarm is given as soon as one leaves the range 2.950 / 3.050 and there would be triggering for example. outside the 2.800 / 3.200 range.
• such a table should be provided for each of the adsorbers, which is possible but which makes the process cumbersome.
• the adjustment method according to the invention is characterized in that the target value is of the general form X + delta Xi, X being the common setpoint relating to the N adsorbers and delta Xi the difference to this common instruction relating to the equipment i.
• the basic principle of the invention is, as we have just seen, to differentiate the pressure cycles per adsorber by introducing, when this improves the overall performance of the unit, a corrective term (delta Xi).
• the simplest way to determine these corrective terms, when possible, is to plan an optimization campaign, for example after starting the unit or preferably periodically, for example every year.
• the following example will illustrate this point. It relates to a VSA type unit producing oxygen at 90 mol% purity from atmospheric air.
• the VSA represented in [Fig.3], comprises 3 identical adsorbers 1,2,3 following in theory the same pressure cycle with a phase time shift of 30 s, an air blower 5 sucking in 1 'air
• Adsorber 1 is in production with a step (a1) dedicated only to production and (bl) during which the final repressurization of adsorber 3 takes place.
• Adsorber 2 begins with a depressurization phase (bl) during which the extracted gas is used to the elution of the adsorber 3 and participates in its recompression.
• the second step is dedicated to vacuum pumping (b2).
• the adsorber 3 passes successively through a step of elution at rising pressure then a step of repressurization with oxygen. It can be seen that on the one hand the durations (a1), (b1) and (c1) must be the same and that the same is true for (b1), (b2) and (b3). These parameters cannot be individualized by adsorber.
• each adsorber supplies and receives gas from the other 2.
• these high and low pressures are parameters on which it is possible to intervene more easily and these pressures would then be individualized by adsorber in the same way as the intermediate pressures.
• the vacuum pump has less gas to be evacuated and should slow down slightly to maintain Pm.
• the effect on the low pressure Pm is small and the speed of the vacuum pump is generally fixed. As stated previously, one could, if desired, modify this speed at each phase time and individualize the low pressures Pm (i).
• This optimization allows gains of up to 1% or more on purity and resulting at the same purity by a flow rate increased by a few percent.
• the method for adjusting a gas separation unit of the PSA type forming the subject of the present application uses, for the determination of Xi, and more particularly of delta Pi and / or delta DPij, corresponding to an optimal functioning of the unit of methods and / or specific optimum search software in the case of multivariable.
• the deviations in the geometry correspond to the respective locations of the various adsorbers and their pipes and to the actual construction of the adsorbers and their internals.
• the adsorbers are generally installed in line, even sometimes on 2 lines when the unit has a large number of them (10 or more).
• the dead volumes can then be different from one adsorber to another.
• Implantation procedures can also affect the circulating flows, especially if several adsorbers operate in parallel over a few stages (for example 2 adsorbers simultaneously in production or in elution).
• some adsorbers will systematically see inflows and / or outflows greater than others. More generally, it will be the impact of pressure drops depending on the path of the connections (effect of the stopping pressure, suction effect, friction losses, etc.).
• the gaps can potentially be much larger when it comes to content despite the varying levels of control.
• the layer of zeolite of LiLSX type used for the separation between O2 and N2 of the air in the VSA or VPSA 02 like that of the example above.
• volume differences can be controlled in the case of radial adsorbers for which the thickness of the beds is fixed by construction between two grids.
• the upper surface of the adsorbent layer is generally a free surface which should be leveled.
• the adsorber 1 contains a little more adsorbent than expected and the adsorber 3 a little less which leads the adsorber 1 to outperform. and the 3 to underperform with regard to nitrogen shutdown.
• this difference can come from a different N2 capacity during production, from a slight pollution during storage or filling ...
• We are moving towards this diagnosis by following the purity of the oxygen at the outlet of each adsorber and by comparing the thermal profiles of the adsorbers. We come back later to the diagnoses that can be made and how to obtain elements for this purpose.
• the adsorber 1 Since the quantity of air treated by adsorber can be considered to be identical, the adsorber 1 has a margin while, conversely, the adsorber 3 risks puncturing prematurely. It will therefore be appropriate to increase the elution of the adsorber 3 a little in order to regenerate it a little better and to recover an additional adsorption capacity due to this better regeneration. It turns out that it is the adsorber 1 which supplies the elution gas. To increase this quantity of gas, the pressure at the end of this stage should be lowered slightly, from 0.7 to 0.68 bar abs. In doing so, there is a tendency to advance the nitrogen a little more at the head of this adsorber 1, which is possible given the margin. The adsorber 3 supplies the elution gas to the adsorber 2.
• the first is to use a small pilot unit on which we create
• the method according to the invention can consist in making a diagnosis of
• the second approach consists in following the same process of differentiation between adsorbers and in analyzing the differences in behavior, but via calculations carried out by means of software for simulating adsorption processes.
• This adjustment method being characterized in that the determination of the end of step set points Xi (in particular delta Pi and / or delta DPij) corresponding to optimal operation of the unit is carried out using a specific search program optimum coupled with the process simulator.
• the pilot can then come as a simulation validation tool.
• the present invention also relates to a unit for separating a gas flow comprising at least two adsorbers A and B which follow a pressure cycle of the PSA, VSA or VPSA type and comprising means allowing the unit to be adjusted. according to the invention.
• the gas stream will be chosen from atmospheric air, a gas comprising hydrogen, a gas comprising CO 2 or a gas comprising CO with said unit intended to respectively produce streams enriched in oxygen, hydrogen or helium , C02, CO or methane.

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• 2019
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