The pressure swing absorption process of valuable gas circulates
The invention belongs to the mist separation technology field; Be specifically related to a kind of through transformation absorption (PSA; Pressure SwingAdsorption) technology realizes the method that raw gas mixture separates; Be particularly related to a kind of pressure swing absorption process of the valuable gas that circulates, realize separation expeditiously, obtain wherein one or more high-purity gas mist.
Transformation absorption (PSA) method is as a kind of advanced person's gas separation; Successfully be applied to oil, chemical industry, electronics, metallurgy, medicine and other fields, such as from hydrogeneous gaseous mixtures such as oil plant catalysis drying gas, petroleum reforming hydrogen rich gas, synthesis ammonia plant off-gas, methanol purge gas, extracting pure hydrogen; From liquefied butane gas, isolate iso-butane and normal butane; From blast furnace waste gas, extract carbon monoxide; Oxygen separation or nitrogen or the like from air.It has a wide range of applications aspect saving energy and reduce the cost, increasing production and improying productivity industrial.
As everyone knows, transformation absorption (PSA) method is used to from the gas mixture that contains at least a difficult absorbed component and at least a easy absorbed component, separate or at least wherein a kind of component of purifying.Based on the theoretical omnibus control system of equilibrium adsorption is most typical PSA separation process representative; This method is in the gaseous flow that is applied to comprise on the Nature of Separation oxygen and nitrogen; Air for example is with zeolite or other sorbing material preferential adsorption nitrogen, so that produce oxygen or the oxygen containing gaseous flow of a kind of richness.From U.S.'s union carbide corporation successfully synthesize the fifties in last century fluorite and thus since, SKARTROM is as far back as United States Patent (USP) U.S 2,944; Announced in the world PSA method the earliest in 627, it is made up of the circulation of following four basic steps: (1) absorption, (2) step-down; (3) purge 4) pressurization again.After this, people have added various steps trial raising process yields and gas purity, have saved energy resource consumption, have reduced the adsorbent consumption, have reduced cost, improved the stability of a system and easy increase-volume expansion this basic adsorption operations circulation.
Known mode shows that the step of all pressing that in the PSA operation cycle, adds has fruitful effect to the raising of system's purity and output, the reduction of energy resource consumption.Because accomplishing the gas of the elevated pressures that the adsorption tower of absorption itself has gets into another adsorption tower or an intermediate buffering jar and gets into systemic circulation once more and carry out adsorbing separation when all pressing; Thereby improved the rate of recovery of product gas; And make adsorption tower rise rapidly at the pressure at the initial stage of boosting, help the raising of purity of product gas.People such as RBanerjee utilize analysis of Available Energy to discuss not have and all press step and the psa process of all pressing step is arranged, and point out all not press step to compare with having, and have the adsorptive pressure of the flow process of all pressing step obviously to reduce, and the oxygen purity and the rate of recovery obviously improve.
In numerous ameliorative measures that psa process is carried out, to utilizing valuable gas that serial of methods is arranged.Numerous research units, manufacturing producer are all doing variedly at aspects such as the efficiency of energy utilization that centers on the raising psa process, reduction device fabrication cost, raising stabilization of equipment performance and are improveing.For example, the multiple mode of all pressing is arranged, like Fig. 1-shown in Figure 7 for the psa process of double tower operation.Therefrom can find out,, reclaim in the equal press operation mode of valuable gas at these for typical 2 PSA systems; Have be obvious at 2: at first, reclaim not thoroughly, recover kinetic energy is half the at most; The component of valuable gas can not reclaim according to the greatest limit that the saturated adsorption tower of absorption can carry out; In case isostasy finishes,, also can't continue to reclaim though still have the component of recyclable utilization in the adsorption tower.Domestic have the patent that reclaims valuable gas kinetic energy and component to report, and like patent 200510062324.9, its summary of the invention provides a kind of can recycle part tail gas, to improve the technology of transformation adsorption method of separation gas reclaiming rate.The tail gas that absorption is produced switches through control, will have the tail gas of recovery value to introduce earlier in the tail gas storage space, with the tail gas supercharging of storing, sends into to reclaim in the unstripped gas air inlet pipeline and uses after the accumulation.We can see very clearly from its summary of the invention, and the tail gas that it hopes to obtain is from the saturated adsorption tower feed end of absorption, rather than product end.These professional personnel can be appreciated that, adsorb so saturated after, the clearance gas of gap space between the adsorption tower product end absorbent particles and a large amount of enrichments of product gas component in the product end pipeline is only the gas of real valuable recovery.Generally speaking; Should discharge adsorbed gas apace to accomplish desorb from adsorption tower feed end adverse current; Adsorbing the gas of discharging since then after saturated is the mixture of unstripped gas, stripping gas and the valuable gas of product end; A large amount of valuable gases since this mixed reduction so that lose recovery value; Its energy reclaims and the material recovery measure obviously is helpless to or can improve system effectiveness rarely, only the excessive product gas for bed cleaning process generation is more completely had the recovery effect.Obviously; Excessive purge gas can be by control scavenging period or other measure with very simply, mode realizes cheaply; Can only cause the further increase of specific energy to this " tail gas " supercharging, even not supercharging does not solve the gas kinetic energy that utilizes adsorption tower itself to have well yet.Because the gas that adverse current ejects must be rapidly; And higher back pressure can not be arranged in the back; So this energy reclaims and reclaims with valuable gas component can only be limited, does not resolve the thorough recovery of component and the key problems such as maximization recovery of energy.
Secondly, those skilled in the art knows that major part all can adopt the device of fixed absorbent during the adsorption tower design, and the gas flow rate of the entering bed of strict limit design, in order that fixed absorbent bed firmly, to avoid the adsorbent fluidisation.Get into the equipment of adsorption tower from top to bottom for unstripped gas; General its air velocity can not surpass 2 times of fluidizing velocity; The air velocity that unstripped gas radially gets into adsorption tower can not surpass 1.5 times of its fluidizing velocity, and unstripped gas gets into the gas flow rate of adsorption tower from bottom to top and can not surpass 0.75 times of its fluidizing velocity.For the pressure equalizing that reclaims valuable gas, gas flow is to begin from the product end that adsorbs saturated adsorption tower, no matter is aforesaid which kind of gas mode of entrance; In this step; The gas of pressure equalizing is flowing out and is flowing into bed that another one is filled with adsorbent in other words during separator, and the step of all pressing that the utmost point short time accomplishes will be brought huge gas shock, thereby cause the adsorbent shortening in service life; Cause too early efflorescence, even moment is destroyed system.For another example, in air, extract in the large-scale PSA system of oxygen with the fluorite molecular sieve, short cycle request is the step of short counterpressure extremely, again such as PSA nitrogen leaching process that carries out with carbon molecular sieve and psa process (so-called RPSA) etc. fast.Prior art does not all solve in the pressure equalizing gas flow well to the stability problem that equipment causes, and causes the gas of reverse flow that bed stability is constituted serious threat.Greater than 80 cubic meters/hours, particularly fatal the psa process of adsorptive pressure more than 5bar for flow, under the impact condition of big load, system half a year, some months possibly occur even just cause the phenomenon of adsorbent efflorescence to take place in several days.Domestic patent 00263040.0 has reported that a kind of unstripped gas gets into from adsorption tower top; And adsorb the method that saturated gas is discharged from the adsorption tower mid portion; Collecting pipe through 1 middle part valuable gas that circulates, and discharge the saturated air-flow of absorption from the middle part.Because adopted unstripped gas to get into adsorption tower from top, the air velocity comparison that itself design allows has bigger permissible value from the bottom gets into or radially get into the adsorbent equipment of gas flow of adsorption tower.Product gas is discharged by the lower end in this patent, because adsorbent has deadweight, can guarantee that the whole moving direction of adsorbent is consistent with its sinking direction; Thereby need not adopt hold down gag; Practice thrift manufacturing cost, improved system reliability, solved the stability problem of system to a certain extent.But can be clear that from the gas flow of its description this patent does not propose the method that these valuable gases are reclaimed in circulation, back flow of gas impacts the phenomenon of bed when still existing pressure equalizing to carry out, and impacts very big.
At present, the technological process that pressure-swing absorption apparatus is most of adopts " pressurization absorption-all pressure-depressurization desorption-blowback is cleaned ".In this technological process; When absorption phase is accomplished; The adsorption tower of accomplishing absorption is done the operating procedure of a counterpressure to the surge tank of the adsorption tower that is about to get into absorption phase or a sky; Make it to rise to an intermediate pressure,, reached certain energy-saving and cost-reducing effect to reclaim the clearance gas in the adsorption tower.But; In above-mentioned cycling process; Do not take into full account the variation of the gas flow, pressure and each partial component pressure that reclaim this circulation step in the adsorption tower of accomplishing absorption; Make in this removal process the physics component, the kinetic energy that both farthest reclaim valuable gas, reduce the systematic jitters that gas shock that cyclic process is easy to generate forms again to greatest extent.That is to say, well do not solve the recovery that in valuable Gas Recovery, realizes gas kinetic energy and component to greatest extent, and the scaling concern of stabilization of equipment performance problem and system is proposed solution.
Summary of the invention
The objective of the invention is to propose that a kind of stability of a system is good, energy resource consumption economizes, the pressure swing absorption process of the valuable gas of recycling capable of circulation.
The pressure swing absorption process of the valuable gas that the present invention proposes; Be in one or more adsorption towers, will contain to be prone to absorbed component and the efficient pressure swing absorption process that separates of difficult absorbed component; Specifically be different according to the pressure of valuable gas and difficult absorbed component purity, circulate in a different manner, reclaim or utilize through the certain methods classification.
The present invention adopts following manner to circulate, reclaim or utilizes valuable gas:
1 is discharged into the intermediate equilibria jar with gas from the adsorption tower product end of elevated pressures, or gas gets into the feed end of adsorption tower from the intermediate equilibria jar of elevated pressures, makes the adsorption tower buck or boost;
2 the valuable gas in the adsorption tower is caused the arrival end of unstripped gas booster from its product end pneumatic reservoir carry out equal step-down;
3 cause the feed end of another adsorption tower that is in lower pressure with gas from the adsorption tower product end of elevated pressures, until the pressure of two adsorption towers balance roughly, make the adsorption tower buck or boost;
4 import the adsorption tower product end with the valuable gases of intermediate equilibria jar through the control valve circulation cleans the adsorption bed in the adsorption tower, and then as requested the product gas of product gas tank is imported to the adsorption tower product end adsorption bed in the adsorption tower is cleaned.
Be applied in the concrete technical process and can implement through following operating procedure:
(1) get into adsorption tower through the unstripped gas that boosts to an elevated pressures, easy absorbed component is adsorbed, and the difficult absorbed component that product end meets the requirements of purity of product gas exports the product gas tank to as product gas;
(2) valuable gas flows to the feed end of another adsorption tower (the PSA systems that a plurality of adsorption towers are formed) or flows to an intermediate equilibria jar (one-level compensator from the product end of the adsorption tower of accomplishing adsorption step; PSA system to single adsorption tower composition); Make latter's pressure rise to an intermediate pressure, be approximately 1/2 of adsorptive pressure;
(3) valuable gas gets into another intermediate equilibria jar (secondary compensator, slack tank is to the PSA system of a plurality of adsorption towers compositions) again, makes latter's pressure rise to the secondary intermediate pressure, makes it pressure and is about 1/4 of adsorptive pressure;
(4) valuable gas is recycled to the hold-up vessel (unstripped gas compensator, slack tank) before the booster from the adsorption tower product end, mixes with unstripped gas;
(5) when adsorption tower product end gas is considered to nugatory, put pressure to accomplish desorb from the adsorption tower feed end immediately;
(6) the valuable gas of compensators at different levels being directed into the adsorption tower product end through the control valve circulation cleans or the suction port of compressor the adsorption bed in the adsorption tower;
(7) product gas of product gas tank can be directed into the adsorption tower product end as requested the adsorption bed in the adsorption tower is cleaned;
What (8) another adsorption tower that gets into absorption phase received is the mixture of valuable gas and unstripped gas; Begin the pressure that raises after the charging; Carry out adsorption process, in this process, the valuable gas of unstripped gas compensator is to import this adsorption tower feed end through the compressor cycle that had originally;
(9) be reduced to the pressure of inspiration(Pi) of former compressor itself when following when the unstripped gas compensator pressure that receives valuable gas, check valve is opened automatically, the suction unstripped gas from the front;
(10) the above-mentioned steps circulation is carried out.
Elevated pressures of the present invention is meant two pressure equalising vessels elevated pressures comparatively speaking.
Valuable gas of the present invention be meant pressure greater than unstripped gas booster arrival end pressure and gas component in other words purity greater than the gas of product component purity in the unstripped gas own.
The PSA system that uses the method for the invention can be made up of the adsorbent bed (adsorption tower) that, two or several preferential adsorption are prone to adsorbed gas component (comparing with difficult adsorbed gas component).
In the system that a plurality of adsorption towers are formed, general adsorption tower laterally arranges, and at least one adsorption tower is at adsorption step, and other adsorbent bed out-phase mode such as then regenerate is operated.Three phases is realized thorough recovery, circulates and utilizes valuable gas through distinct methods below:
1, successively through the valuable gas in the adsorption tower that will accomplish adsorption step from its product end flow to another adsorption tower feed end, get into the intermediate equilibria jar, the modes such as hold-up vessel that are recycled to before the booster from the adsorption tower product end come the equal step-down of classification;
2, the valuable gas that utilizes compensators at different levels earlier gets into from the adsorption tower product end adsorption bed in the adsorption tower is cleaned, and the adsorption bed in the adsorption tower is cleaned from the entering of adsorption tower product end with the product gas of product gas tank as required again;
3, coming rationally to utilize the adsorption tower of intermediate equilibria jar, needs step-down and absorber that the valuable gas in the hold-up vessel boosts to needs to carry out classification according to the pressure size cases in each container all presses or boosts.
But the present invention does not get rid of yet and only adopts an adsorption tower, and adopts at least one empty intermediate equilibria jar or surge tank to realize the purpose of Gas Recovery.And a plurality of adsorption tower differences only are to have lacked all pressing each other between the adsorption tower in each stage.
Can be according to concrete performance; Arrange all to press, utilize between the adsorption tower in each stage the intermediate equilibria jar all to press and be back to the mutual combining form of hold-up vessel; Such as all pressures that can save between the adsorption tower, perhaps economize all pressures of whereabouts intermediate equilibria jar.
Like Fig. 8 and shown in Figure 9; Fig. 8 is the direction of flow of all calming the anger of typical 2 psa processes; Fig. 9 is all pressures of a typical single psa process, utilizes the surge tank of a sky and necessary control valve can solve the thorough problem of recovery preferably and help the stable of bed gas flow.
Above-mentioned steps 4 is recycled to the hold-up vessel (unstripped gas compensator, slack tank) before the booster with valuable gas from the adsorption tower product end, mixes with unstripped gas to improve raw gas pressure and difficult absorbed component purity.At this moment, its removal process because the existence of booster can be completely, unconfined, and do not increase or increase specific energy seldom.
Above-mentioned steps 5 is put pressure to accomplish desorb from the adsorption tower feed end immediately when adsorption tower product end gas is considered to nugatory.Obviously, it is much little than prior art to the impact of bed that the adverse current of this moment is put the pressure process, and this moment, any technique known means can be utilized such as bed being introduced that product gas cleans etc.And different with other technological means be; The present invention can utilize the low-purity gas of having collected, and for example, can in through the slack tank of collecting, add some fillers; Realize that easily the gas that bed increases progressively with different purity is carried out bed to be cleaned, and re-uses product gas at last and cleans.So not only can reduce reuse, and obtain better economic benefit and efficient product gas.
In the psa process in the present invention; At least comprise the cyclic process of the valuable gas after absorption is saturated; It is to flow to the feed end of other adsorption tower or the compensator that communicates with unstripped gas from product end, reclaims the kinetic energy and the valuable gas component of gas.
The present invention can be used for separating any gas that is difficult for being adsorbed with a kind of adsorbent from any other gas that is prone to absorption, be prone to absorbed component or difficult absorbed component can be separately or the while as required product gas.For example, the N of production enrichment simultaneously from air
2, the perhaps N of production enrichment from flue gas
In the adsorption tower of the present invention, can adopt multiple adsorbent to be arranged to one or more layers main adsorbent layer and reclaim needed gas component, the multicomponent that disclosed method can be used for other separates.Being used for estimating and selecting to reclaim the easy perhaps method of the adsorbent of difficult absorbed component is a kind of known method; Can use any combination of one or more suitable adsorbents to adsorb; For example; Be not limited to use CaA zeolite, LiX zeolite, or any other specific adsorbent reclaim oxygen, more difficult being selected property adsorbed components promptly is required product.In this respect, include but not limited to following separate use: the adsorbent with selecting nitrogen from air, reclaims oxygen; Adsorbent with selecting oxygen from air, reclaims nitrogen; With selecting CO
2Adsorbent come from gasification of coal, to reclaim carbon monoxide; Adsorbent with selecting CO from gasification of coal, reclaims carbon dioxide; Use or select oxygen or select the adsorbent of nitrogen to realize that oxygen/nitrogen separates.
Therefore, just just be shown in accompanying drawing to concrete property of the present invention for ease or explain in this paper.Because according to the present invention, these characteristics also can combine with other characteristic.Those skilled in the art can admit that other embodiment that can in practice of the present invention, use also should be included within the scope of accompanying claims.
In the present invention; Said transformation absorption (PSA) method indication is not only the PSA method; Also comprise similar with it method, like Vacuum Pressure Swing Adsorption (Vacuum Swing Adsorption-VSA) or blend pressure transformation absorption (Mixed PressureSwing Adsorption-MPSA) method or the like.
In addition, " transformation absorption (PSA) " will be understood on broader meaning, that is to say, for the high pressure of periodic cycle, can comprise more than or equal to atmospheric pressure, and the low pressure of periodic cycle then comprises and is less than or equal to atmospheric pressure.
The pressure that the present invention mentions is absolute pressure.
Adsorption tower (bed), indication are the container that one or more adsorbents are housed, and adsorbent has stronger adsorption capacity to being prone to adsorbed components in the mist.
The difficult absorbed component of describing among the present invention is meant that for more or less freely adsorbed components same, easy absorbed component then is meant for more difficult adsorbed components.
" valuable gas " in the indication of the present invention circulation has been meant available gas kinetic energy and available gas component, is meant that generally pressure is greater than unstripped gas booster arrival end pressure and the product gas component purity gas greater than product gas component purity in the unstripped gas.
Priority application of the present invention is in based on the equilibrium adsorption theory and the psa process of non-dynamics separation theorem, but the psa process of not getting rid of based on the dynamics separation theorem can adopt the present invention to realize the object of the invention.Disclosed basic principle can be used for much other separation occasions.Can realize that through method of the present invention the representative instance that separates comprises the separation of oxygen/nitrogen, the separation of carbon dioxide/methane, separation, the separation of hydrogen/nitrogen and the separating of olefin/paraffin of titanium dioxide carbon/nitrogen gas.In the psa process theoretical based on equilibrium adsorption, from the gas that contains nitrogen and oxygen for example the air separation of nitrogen or oxygen be most typical representative.Following is that example is described technical characterictic of the present invention with the PSA oxygen preparation mainly.
A series of measures that the present invention proposes can combine improvement on some transformation adsorption operations methods to realize keeping the stability of a system and improve advantage such as operating process, make adsorption process carry out according to the theoretical basis of equilibrium adsorption fully.
The present invention proposes a kind of asymmetric absorption notion and realize a kind of more efficient cycling process.Can be through said method with the adsorption process independent of separation, thus realize asymmetric absorption.Asymmetric absorption just to each online adsorption tower, adsorb and is saturatedly promptly switched, and regenerating thoroughly promptly changes absorption over to, effectively raises production capacity, also indirect raising efficient, and reduced the adsorbent consumption to a certain extent.And the announcement of this operating characteristic can be expanded system throughput easily, and each discrete adsorption tower can be different.To the operation of original sorption cycle, generally be incorgruous operation, A tower B tower in absorption must be to do a similar work step, even and work step has been accomplished, need wait for also switching to next procedure together after A accomplishes that this has obviously wasted timeliness.After adopting the present invention; A, B can be fully independently, operate according to the inherent characteristic of the loadings of adsorption tower own; Saturatedly promptly switch, regeneration thoroughly promptly changes absorption over to, between the tower through the series of operation step under the situation that does not influence system recoveries rate, energy resource consumption; Realized this process cheaply, this is unprecedented.By means of this process operation principle, can maximally utilise molecular sieve, reduce the consumption of adsorbent.
PSA separation process of the present invention can be asymmetric, just can be with by this asymmetrical operator scheme, and this will help the infinite expanding of equipment yield the sort run that makes that psa process is similar need not be according to symmetry the time, preferably resolve stability of a system problem.So just overcome the weakness of psa process; And make psa process of the present invention a similar film separation process to have realized that equally increase-volume is easy; It need not adsorption tower size consistent; Even the molecular sieve of filling in need not adsorption tower is consistent, can be according to the process yield of any design demand of adsorbent loadings of psa process needs, and this is unprecedented.
Gas separation method provided by the invention comprises the PSA method of the improvement of VPSA, VSA.
Carry out the PSA/VPSA/VSA modification method that high-purity gas reclaims provided by the invention comprising through gas separating method.
Enhancing energy efficiency provided by the invention, the PSA method that reduces specific energy consumption, enhanced system adsorption capacity, improved operating process stability and effectively expanded comprise the VPSA method.
In the present invention, also comprise one need not bed connection effect example, it can be with the adsorption process independent of separation, thereby realizes asymmetric absorption.
To sum up; Pass through the method for the invention; Make pressure and the difficult absorbed component of valuable gas form classification, adopt different modes to circulate, reclaim or utilize; Reclaimed valuable constituent more up hill and dale, reclaimed gas kinetic energy more efficiently, realized this significant process with minimum cost.More be worth special propose be, through a unstripped gas compensator is set, make in these valuable gases of circulation, can cancel alternatively between tower and all pressing, can be asymmetric thereby make adsorption process.When also making these valuable gases of circulation in addition; The stability that can keep the harmless process equipment of gas flow of pressure equalizing; Solve the problem that prior art exists satisfactorily, improved efficient, strengthened the stability of system; Expand operator scheme, and solved the problem of system's production capacity expansion.
The serial of methods that the present invention adopts can be carried out the recovery of desired valuable gas effectively up hill and dale, in the situation that does not increase mechanical energy, has solved thorough recovery cheaply in other words according to the problem of oneself expecting to reclaim.The invention provides a kind of pressure swing absorption process of the valuable gas that circulates, or rather, is through the valuable gas that circulates; Improved the energy efficiency of psa process; More effectively reclaimed valuable gas component,, improved the stability of equipment with extremely low cost.In addition, the more important thing is the increase-volume expansion that the invention solves the PSA operating process.
Description of drawings
One of the original all pressures of Fig. 1 mode.
One of the original all pressures of Fig. 2 mode.
One of the original all pressures of Fig. 3 mode.
One of the original all pressures of Fig. 4 mode.
One of the original all pressures of Fig. 5 mode.
One of the original all pressures of Fig. 6 mode.
One of the original all pressures of Fig. 7 mode.
Fig. 8 mode of all pressing of the present invention.
Fig. 9 mode of all pressing of the present invention.
A kind of technological process of the preferred single adsorption tower of Figure 10 the present invention.
A kind of technological process of the no pans of preferred two adsorption towers of Figure 11 the present invention.
A kind of technological process that pans are arranged of preferred two adsorption towers of Figure 12 the present invention.
Label among the figure: 1 is the unstripped gas compensator, and 2 is booster, and 3 is compensator; 4 is adsorption tower (bed), and 4A is adsorption tower (bed), and 4B is adsorption tower (bed); 5 is the product gas tank, and 6 is unidirectional time only valve, and 7 is the booster control valve; 8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24 is valve, and 25 is the secondary compensator.
The specific embodiment
Below the specific embodiment through example forms, foregoing of the present invention is remake further detailed description.But should this be interpreted as that the above-mentioned subject area of the present invention only limits to following instance, allly all belong to scope of the present invention based on the technology that content realized more than the present invention.
Present embodiment is to be that example illustrates in greater detail the present invention with the embodiment of describing among Figure 10 with single adsorption tower:
In single adsorption tower, utilize zeolite adsorbent that air separation is become the oxygen product of highly purified difficult absorption, and discharge nitrogen as the easy absorbed component of byproduct gas.Raw air is through behind the one way stop peturn valve 6; Get in the unstripped gas compensator 1 and mix with the valuable gas (putting of adsorption tower calmed the anger) that reclaims, when the pressure of unstripped gas compensator 1 raises owing to clearance gas, raw air will not pass through check valve 6; But when the pressure of clearance gas in the unstripped gas compensator 1 reduces; Air will begin to mix through control valve 7 and with remaining clearance gas in the unstripped gas compensator 1, and the raw air that comprises some clearance gas boosts to adsorptive pressure through behind the control valve 7 in booster 2; The adsorption bed that then gets into adsorption tower 4 through valve 9; Nitrogen is adsorbed, and oxygen obtains enrichment and discharges from the adsorption bed product end as product gas, collects in the product gas tank 5 through valve 13.After after a while; (nitrogen is about to penetrate adsorption bed to adsorption bed downstream nitrogen adsorption in the adsorption tower 4 near saturated; Oxygen purity is reduced to when being lower than product gas requirement purity possibility), valve-off 13, Open valve 12 make valuable gas flow to the intermediate equilibria jar 3 from the adsorption tower product end; When the pressure in the middle compensator 3 rise to be approximately adsorptive pressure 1/2 the time; Valve-off 12, Open valve 11 makes valuable gas import the unstripped gas compensator 1 to improve raw air pressure and oxygen purity from the product end of adsorption tower 4.When the non-valuable gas of backflow gas (oxygen purity is near 21%), valve-off 11, Open valve 8 makes adsorption tower 4 adverse current emptying with valve 9.Valve-off 8 and valve 9 after emptying finishes, 13 pairs of adsorption towers of Open valve clean, after cleaning completion; Close respective valves, Open valve 10 evenly imports the valuable gas in the intermediate equilibria jar feed end of adsorption tower bed; The pressure of its adsorbent bed is constantly raise, when its pressure is elevated to equalizing pressure, close corresponding valve 10; Open valve 7 makes adsorption column pressure rise to adsorptive pressure with valve 9, gets into to adsorb aerogenesis once more.Step above repeating is operated.
Present embodiment is to be example illustrates in greater detail a plurality of adsorption towers preferred for this invention with the embodiment of describing among Figure 11 pressure swing adsorption system with two adsorption towers:
In the adsorption tower of two parallel connections, utilize zeolite adsorbent that air separation is become the oxygen product of highly purified difficult absorption, and discharge nitrogen as the easy absorbed component of byproduct gas.Raw air is through behind the one way stop peturn valve 6; Get in the unstripped gas compensator 1 and mix with the valuable gas (putting of adsorption tower calmed the anger) that reclaims; When the pressure in the unstripped gas compensator 1 because clearance gas lift when high; Raw air will not pass through check valve 6, but when the reduction of the pressure of clearance gas in the unstripped gas compensator 1, and air will begin to mix through check valve 6 and with remaining clearance gas in the unstripped gas compensator 1; The raw air that comprises some clearance gas boosts to adsorptive pressure through behind the valve 7 in booster 2.The adsorption bed that then gets into adsorption tower 4A through valve 14, nitrogen is adsorbed, and oxygen obtains enrichment and discharges from the adsorption bed product end as product gas, collects in the product gas tank 5 through valve 21.After a time period, the adsorption bed downstream nitrogen adsorption among the 4A is near saturated (nitrogen is about to penetrate adsorption bed, and oxygen purity is reduced to when being lower than product gas requirement purity possibility); This moment valve-off 21; Open valve 19 and valve 17 are communicated with two adsorption towers, and 4B all presses to adsorption tower.When the pressure in the adsorption tower 4B reaches the about 1/2 time of adsorptive pressure, valve-off 17, Open valve 11 makes valuable gas import the gas balance jar 1 to improve raw air pressure and oxygen purity from the adsorption tower product end.When the non-valuable gas of backflow gas (oxygen purity is near 21%), valve-off 19 and valve 11, Open valve 16 and valve 18 make the emptying of adsorption tower 4A adverse current.Emptying finishes back valve-off 16 and valve 18, and 21 couples of adsorption tower 4A of Open valve clean.After cleaning completion, close respective valves, Open valve 20 and valve 16; Valuable gas among the adsorption tower 4B that gets into desorb is evenly imported the feed end of adsorption tower bed; The pressure of its adsorbent bed is constantly raise, when its pressure is elevated to middle pressure, close corresponding two valves; Open valve 14 makes adsorption column pressure rise to adsorptive pressure with valve 7, gets into to adsorb aerogenesis once more.Step above repeating is operated.
Present embodiment is to be example illustrates in greater detail a plurality of adsorption towers preferred for this invention with the embodiment of describing among Figure 12 pressure swing adsorption system with two adsorption towers:
In the adsorption tower of two parallel connections, utilize zeolite adsorbent that air separation is become the oxygen product of highly purified difficult absorption, and discharge nitrogen as the easy absorbed component of byproduct gas.Raw air is through behind the one way stop peturn valve 6; Get in the unstripped gas compensator 1 and mix with the valuable gas (putting of adsorption tower calmed the anger) that reclaims; When the pressure in the unstripped gas compensator 1 because clearance gas lift when high; Raw air will not pass through check valve 6, but when the reduction of the pressure of clearance gas in the unstripped gas compensator 1, and air will begin to mix through valve 6 and with remaining clearance gas in the unstripped gas compensator 1; The raw air that comprises some clearance gas boosts to adsorptive pressure through behind the valve 7 in booster 2.The adsorption bed that then gets into adsorption tower 4A through valve 14, nitrogen is adsorbed, and oxygen obtains enrichment and discharges from the adsorption bed product end as product gas, collects in the product gas tank 5 through valve 21.After a time period, the adsorption bed downstream nitrogen adsorption among the 4A is near saturated (nitrogen is about to penetrate adsorption bed, and oxygen purity is reduced to when being lower than product gas requirement purity possibility); This moment valve-off 21, Open valve 19 and valve 17 are communicated with two adsorption towers; 4B all presses to adsorption tower, when the pressure in the adsorption tower 4B reaches the about 1/2 time of adsorptive pressure, valve-off 17; Open valve 24, all go into secondary compensator 25, all press back shut off valve 24; Open valve 23 makes valuable gas import the unstripped gas compensator 1 to improve raw air pressure and oxygen purity from the adsorption tower product end.When the non-valuable gas of backflow gas (oxygen purity is near 21%), valve-off 19 and valve 23, Open valve 16 and valve 18 make the emptying of adsorption tower 4A adverse current.Emptying finishes back valve-off 16 and valve 18, opens valve 19 and 24, tentatively cleans with gas in the secondary compensator 25 earlier, cleans back shut off valve 19 and 24, and 21 couples of adsorption tower 4A of Open valve clean.After cleaning completion, close respective valves, Open valve 20 and valve 16; Valuable gas among the adsorption tower 4B that gets into desorb is evenly imported the feed end of adsorption tower bed; The pressure of its adsorbent bed is constantly raise, when its pressure is elevated to middle pressure, close corresponding two valves; Open valve 14 makes adsorption column pressure rise to adsorptive pressure with valve 7, gets into to adsorb aerogenesis once more.Step above repeating is operated.
Opposite with prior art, like the above-described preferred embodiment of the invention, the present invention has many advantages: for example, owing to adopt the identification of valuable gas, and with in addition recycle of valuable gas classification, the rate of recovery of product gas improves.And during the shut-in time of inlet one way stop peturn valve, compensator receives valuable gas, and pressure raises, and has just saved the power that booster boosts.Compare with the general method of prior art, the adsorbent bed pressure before being vented to atmospheric pressure is lower, and therefore, method of the present invention has reduced the noise when also having reduced toxic emission when the rate of recovery had the discharging of counteractive exhausted air quantity.Moreover; During the part of circulation; Because the inlet pressure of valuable gas that contains circulation so the thing amount that goes out of booster has increased, also further reduces the size of feed compressor greater than the air of the standard atmospheric pressure of the prior art processes process pressure as real unstripped gas.
During whole circulation, because method of the present invention adopts all pressure of adsorption tower product end to feed end, even cancels all pressures between tower alternatively, the direction of its gas flow is consistent, has avoided the fluidisation of adsorbent under the effect of high pressure inverted draft
In addition, in the present invention, the method and the prior art of clearance gas being carried out classification cycle are conflicting, and this produces very large influence to product yield and the yield with the conflicting this method of art methods.Through suitable layout equipment of the present invention; Make the only product end direction appearance downstream of the mobile direction of the high-speed gas that when clearance gas is put pressure and exhaust, possibly occur; This has just been avoided the fluidisation of absorbent particles in the adsorption tower, has also avoided the various stationarity requirements of the absorbent particles that prior art must consider in all pressing.
What specify is, two adsorption towers among Figure 11 have any tower purity to occur to descend in the time of can not satisfying product gas and require, in certain limit; System still can adapt to automatically, can not influence the purity of product gas, under the particular case; System can be set at two tower independent operatings or the operation of single tower; This some the time be very useful, also be feasible, this just for operate with failure, maintenance maintenance brought unexpected benefit.
Whether to judge valuable gas; And the system that moves by the pressure and the purity of valuable gas needs more intelligent control program support; But experienced technical staff possibly have been found that; Although seem that control is more complicated, implement not difficultly, the debug process of equipment almost is exactly that system self-adaption arrives stable process.On failure judgment, control program will give the maintenance and repair personnel information more fully, even direct specified fault point.
In that more than describe or the method and apparatus shown in the drawings, can make various changes and can not deviate from scope of the present invention.Therefore, what use is the structural form of any requirement, promptly or two adsorption towers and one or more hold-up tank of fixed volume or fixation pressure though this method is preferred, this method plural adsorption tower also capable of using and a plurality of hold-up tank.Moreover the present invention can use axial flow, radial flow, lateral flow or other pattern through the air-flow pattern of adsorption tower.About single adsorption tower, each all can include a plurality of main adsorption layers, perhaps also can not or be provided with one or more pretreatment layer in order to adsorb other component such as steam.In addition, each adsorbent layer can comprise the adsorbent of single variety or the mixture of two or more adsorbent.
Just shown in the drawings or explain that in preceding text because according to the present invention, these characteristics also can combine with other characteristic for ease concrete property of the present invention.Those skilled in the art can admit that other embodiment that can in practice of the present invention, use also should be included within the scope of accompanying claims.