CN101869797B - Method and apparatus for extracting high-purity nitrogen from air - Google Patents
Method and apparatus for extracting high-purity nitrogen from air Download PDFInfo
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Abstract
The invention, which belongs to the technical field of gas separation and adsorption, particularly relates to a method and an apparatus for extracting high-purity nitrogen from the air. The apparatus comprises adsorption towers loaded with carbon molecular sieves, a vacuum pump for desorption, a pipeline for supplying the raw air to the adsorption towers, necessary control valves thereof, a pipeline for carrying out atmospheric-pressure desorption and capable of being switched to the inlet of the vacuum pump to carry out vacuum desorption, necessary control valves thereof, a gas product buffer tank, an oxygen transfer-preventing balance tank and the like. The method includes the following steps that: adsorption is carried out with adsorbent under the condition of pressurization, desorption is carried out under the vacuum condition, an enhanced circulation step for controlling the transfer of target gas and an effective method for preventing oxygen transfer are adopted for assistance, high-purity nitrogen with less than 3ppm of oxygen content is directly produced with the gas mixture of nitrogen and oxygen as raw gas, and moreover, the method is characterized by short starting time.
Description
Technical field
The invention belongs to gas and separate and the adsorption technology field, be specifically related to a kind of method and apparatus that from air, extracts high-purity nitrogen.
Background technology
High-purity nitrogen is the basic gas of important basic industry such as electronics, metallurgy; Analyze industry and also need a large amount of calibrating gas such as chromatogram etc.; These gases mostly require to have very low impurity content, at present, these gases all rely on basically the empty mitogenetic production fluid nitrogen of deep cooling through vaporizing after with the whole bag of tricks purification and get; Complex manufacturing, with high costs.
In the empty technical field of dividing of non-deep cooling; Oxygen content generally adopts pressure swing adsorption or membrane separation technique less than the production of the high-purity nitrogen of 3ppm; Produce the thick nitrogen of purity about 98～99.9% earlier, make with extra care purification with this unstripped gas again, the typical case of subtractive process representative as:
Chinese patent CN1059130A has described and has a kind ofly carried out air separation with film or pressure swing adsorption system, and the thick nitrogen that obtains is thus circulated into catalytic combustion system, makes residual oxygen and hydrogen reaction to produce the high pure nitrogen product.The nitrogen product of producing through this method can be controlled its oxygen content less than 10ppm or still less, and is typical like 1ppm, still; The excessive hydrogen that contains reaction needed in its product gas, about 1000ppm, obviously; In the application scenario responsive to hydrogen, this technological deficiency has limited its application;
And for example, Chinese patent CN1178768A has described and has surpassed the hydrogen of metering than about 200～500ppm a kind of the adding according to oxygen content in the nitrogen, through first order clarifier; Under the effect that contains precious metals pd and/or Pt dehydrogenation catalyst, the oxygen in the thick nitrogen is purified to below the 1ppm, purify the residual hydrogen in the nitrogen of back; Again through second level clarifier; Under the effect that contains precious metals pd/manganese oxide regulating catalyst, be removed to below the 1ppm, obtain O
2, H
2Content all is lower than the high purity nitrogen of 1ppm.
And for example; Numerous patents have also been described other a kind of technology path; Carry out air separation with film or pressure swing adsorption system, the thick nitrogen stream that obtains is thus adopted the carbon carrier deoxidation, minor amounts of oxygen that contains in the thick nitrogen and the generation chemistry of the carbon in the catalyst (oxidation) reaction are generated carbon dioxide with carbon carrier catalyst (running stores); Again with pressure swing adsorption with this carbon dioxide eliminating, be purified to the high pure nitrogen that complies with the national standard requirements;
Obviously; That more than describes all exists a common trait with the empty various technology paths that divide of non-deep cooling; Another kind of auxiliary material promptly when producing high-purity nitrogen, have been consumed; Typical auxiliary material are hydrogen or carbon, under catalytic condition, the oxygen that contains in the thick nitrogen are dispeled through chemical reaction; And; Wherein, In the purification techniques route of deoxidization by adding hydrogen, consuming hydrogen not only also need continue remaining hydrogen in the moisture that generates and the deoxidation process is removed the high purity nitrogen that meets GB/T8980-1996 " high purity nitrogen " technical indicator that just can produce truly; In with carbon carrier catalyst purification techniques route, not only consume carbon carrier, also need continue the carbon dioxide that generates is removed the high purity nitrogen that meets GB/T8980-1996 " high purity nitrogen " technical indicator that just can produce truly;
In addition, the non-deep cooling sky of above-mentioned these divides technology, makes and produces the very complicacy that oxygen content is lower than the high pure nitrogen production process change of 3ppm, and the device maintenance cost is high; Especially in some high-purity nitrogen application facet that has higher requirements to target components; The application scenario that strict demand is typically arranged such as carbon dioxide, carbon monoxide, hydrogen equal size; The product gas that adopts above technology path to obtain is difficult to meet the demands, and these technological employings in other words will strengthen the technical risk on using; What is more, is difficult to obtain the application scenario of supply at some hydrogen or carbon carrier, adopts the empty branch technology of above-mentioned these non-deep coolings to become unrealistic.
As everyone knows; Transformation absorption (Pressure Swing Adsorption; PSA) be a kind of important, gas separating method with extensive use; Nitrogen making method by pressure swing adsorption realizes that to the rate of adsorption difference of the oxygen in the constituent of air, nitrogen gas separates with carbon molecular sieve (CMS); Require little application scenario in output, adopt the PSA method to have more economy, the pressure-swing absorption apparatus of forming with one or more at least adsorbent beds and at least one or a plurality of air accumulator and fluid switch valve, control system etc.; Can for the user provide a kind of relatively inexpensive, the nitrogen gas purity scope is the on-the-spot air supply method of 90～99.9995% (no oxygen content, oxygen content is less than 5ppm) flexibly.
But up to now, the professional and technical personnel carried out many-sided trial; Adopt this making nitrogen by pressure swing adsorption process based on the dynamics separating mechanism; Its product nitrogen gas purity that can reach of easy device under atmospheric pressure to regenerate all is limited in the nitrogen gas purity (no oxygen content, oxygen content is less than 5ppm) within 99.9995%, and; Often efficient is not high, does not all obtain satisfied result.
Existing research shows, the high-purity nitrogen that wants to adopt pressure swing absorption process production oxygen content to be lower than 3ppm is difficulty very, and ultimate challenge is to obtain high-purity nitrogen like how minimum consumption.Known, all pressing is to improve the fruitful method of the rate of recovery, and the method for especially all pressing with bed in the band is more useful to producing high-purity nitrogen.In the method that bed is all pressed in various bands; With United States Patent (USP) China publication number CN1185577A is the typical case; The all gases that has comprehensively disclosed in bed all is pressed in comprising shifts the method that can effectively improve the rate of recovery; Obtain " high-purity nitrogen " (no oxygen content, oxygen content is less than 5ppm) with less cost.But the professional and technical personnel can understand, even like this, its product gas technical indicator is to be difficult to meet the high purity nitrogen of GB/T8980-1996 " high purity nitrogen " technical indicator, and its purity range still is confined to the 5ppm oxygen content.
The deficiency that part has disclosed prior art is more than described; These deficiencies cause its purity of making nitrogen by pressure swing adsorption of prior art still to be limited in 99. 9995% (no oxygen content; Oxygen content is less than 5ppm) in, the product gas of producing through these methods is difficult to satisfy the high purity nitrogen (oxygen content is less than 3ppm) that meets GB/T8980-1996 " high purity nitrogen " technical indicator.And even produce the high-purity nitrogen of low oxygen content, absorbing process also attaches bed because of making the many factors such as otherness that produce because of gas feed flow rate, environment temperature, double suction, is difficult to the product gas component is stabilized in the scope of requirement.
Summary of the invention
The objective of the invention is to propose a kind of, directly in air, extract the method and apparatus of the high pure nitrogen meet GB/T8980-1996 " high purity nitrogen " technical indicator, to solve the deficiency of above-mentioned technology according to the pressure swing adsorption principle.
The extraction that the present invention proposes meets the method for the high pure nitrogen of GB/T8980-1996 " high purity nitrogen " technical indicator, is unstripped gas with the gaseous mixture (particularly air) that contains nitrogen and oxygen, therefrom produces high pure nitrogen, and concrete steps are following:
1, will be in the saturated first adsorbent bed product end that be about to switch of absorption and be connected with the second adsorbent bed product end, the first adsorbent bed gas that will have a higher operating pressure is transferred to second adsorbent bed from product end;
2, first adsorbent bedly stops charging, and will accomplish that gas shifts first adsorbent bed through feed end to the atmosphere release; Meanwhile, will clean and be pressurized to predetermined pressure to the second adsorbent bed oxygen that carries out adverse current from its product end, to suppress the second adsorbent bed oxygen migration away from product end from the gas of the higher degree of back level buffer system;
3, to the second adsorbent bed adding unstripped gas with its pressure of rapid lifting to normal sorption pressure; Meanwhile, first adsorbent bedly through being unloaded, atmosphere is depressed near normal pressure;
4, will unload and be pressed onto near the atmospheric first adsorbent bed vacuum desorption that carries out, get rid of the inner waste gas of bed, set up certain negative pressure up to bed with vavuum pump; Meanwhile, unstripped gas produces the higher nitrogen of concentration as product gas through second adsorption bed, gets into back level gas buffer jar and exports as product gas;
5, continue to get rid of the waste gas of the first adsorbent bed inside, and introduce product gas this adsorbent bed oxygen that carries out adverse current is cleaned with vavuum pump; Meanwhile, unstripped gas produces the higher nitrogen of concentration as product gas through second adsorption bed, gets into back level gas buffer jar and exports as product gas;
Above-mentioned 1)～5) step is a complete half period;
By above step; When step 5) finishes; Second adsorbent bed being in has higher operating pressure when approaching absorption is saturated to be about to switch; Be about to carry out the second adsorbent bed course, the first adsorbent bed gas and shift,, carry out the pressure-swing absorption process of an operate out of phase according to the sequence of steps of as above narrating;
Repeat above-mentioned steps, promptly form a complete transformation absorption running;
Among the present invention, the adsorptive pressure of adsorbing separation is 3～15bar (gauge pressure), preferred 6～10ba r (gauge pressure).
Among the present invention, said adsorbent bed be two or more, and these beds are out-phase operations through above-mentioned steps.
Among the present invention, the said adsorbent bed adsorbent that a kind of preferential adsorption oxygen is installed at least, no matter it still is an equilibrium adsorption mechanism for the dynamics absorption mechanism, and is preferred but inessentially include one or more pretreatment layer, in order to adsorb other component such as steam.And each adsorbent layer can comprise adsorbent or two or more adsorbent mounting layer, the perhaps adsorbent layer of two or more adsorbent mixtures of single variety.
Among the present invention, said adsorbent bed have at least one arrival end and at least one port of export, arrival end also is feed end, and the port of export can be described as product end or non-feed end; And adsorbent bed air-flow pattern can be axial flow, radial flow, lateral flow or other pattern.
In the step 1 of the present invention, preferred but inessentially keep adsorbent bed charging at a slow speed when product end is communicated with, the flow rate of charging can be 5%～80% of a normal feed flow rates at a slow speed;
In the step 2 of the present invention, the adsorbent bed charging completion gas that stops to shift the back to the atmosphere release, preferably directly to the atmosphere release, extracts the waste gas release but do not get rid of with power-equipments such as vavuum pumps.
In the step 2 of the present invention, level buffer system preferred two or more gas buffer jars that are connected in series in back perhaps are connected with the programmed logic control valve with check valve between the said gas buffer jar; Only do not adopt a product gas surge tank as back level buffer system but do not get rid of; And; At one anti-oxygen being installed moves in the system of compensator; Adsorbent preferably is installed, and preferably loads oxygen absorbent, or the adsorbents such as activated alumina of active carbon, silica gel, activated alumina or the chemical modification of 4A zeolite, active carbon, chemical modification.
In the step 2 of the present invention, the adsorbent bed oxygen that carries out adverse current from its product end is cleaned and is pressurized to predetermined pressure from the gas of the higher degree of back level buffer system, its predetermined pressure be the highest adsorptive pressure 30%～90%, be preferably 50～70%;
In the step 3 of the present invention, to adsorbent bed adding unstripped gas with its pressure of rapid lifting to normal sorption pressure, preferably close being communicated with of product end and back level surge tank, carry gas but do not get rid of toward product end.
In the step 3 of the present invention, preferably, do not efflux but do not get rid of with vavuum pump extraction bed waste gas through atmosphere being unloaded the normal pressure that is depressed near 0.15～1atm (gauge pressure).
In the step 4 of the present invention,, bed is set up the vacuum of 10～90KPa (absolute pressure), the vacuum of preferred 30～70KPa (absolute pressure) with vavuum pump continuous drawing bed waste gas.
Among the present invention, bed regeneration is adopted and is vacuumized the method realization bed waste gas desorb that combines with the product end gas purging.
Among the present invention; It is continuous vacuumizing in the step 4,5; The product end gas purging is continuous or intermittence in the step 5; And purging used product end gas can be from anti-oxygen migration compensator, product gas surge tank, perhaps before collected in other beds, surge tank or the pipeline of higher degree gas one or several.
Among the present invention, when Connection Step finished between the bed, each bed layer pressure was balance or unbalanced.
The present invention adopts pressure swing adsorption, comprises pressurization absorption, negative pressure desorb, and the auxiliary circulation step that shifts with the control object gas that strengthens, and the step of effectively anti-block migration directly extract high-purity nitrogen in air.
With the auxiliary technology path that consumes (hydrogen, carbon carrier) comparatively speaking the non-deep cooling of the employing of the present invention and foregoing description is empty divides; Need not auxiliary material first; Expanded its application scenario; Second because of not containing the common unacceptable gases of user such as hydrogen, carbon monoxide, hydro carbons in the raw air usually, thereby make the quality of product gas be superior to existing any technology, reduced that the user adopts various technology and the technical risk of bringing because product gas contains other undesired component that causes; And this extra power that adopts the negative pressure desorb to consume seems insignificant at this.
Comparatively speaking the pressure swing adsorption of the present invention and employing usually because of adopting vacuum desorption, has reduced to greatest extent to clean and has used high-purity nitrogen; The extra power that forms negative pressure and need to consume with clean comparatively speaking with the value of required usually high-purity nitrogen, have more efficient.
Among the present invention; The circulation step that the control object gas that strengthens shifts; The technology that can adopt band product end gas to shift realizes; The processing step that also can adopt band mid point gas to shift, it is the typical case with United States Patent (USP) China publication number CN1185577, all gases that has comprehensively disclosed in bed all is pressed in comprising shifts the method that can effectively improve the rate of recovery.
Among the present invention, the method for effectively anti-block migration, preferred but non-essential processing step can further improve usefulness as one;
The high-purity nitrogen of indication of the present invention is meant oxygen content at least less than the high-purity nitrogen of 100ppm, and is preferred, is that oxygen content is less than 3ppm, until the high-purity nitrogen less than the 0.5ppm oxygen content.The inventive method also can be separated 95～99.99% nitrogen from air.
Another one beneficial effect of the present invention is the problem that solves present high-purity nitrogen device of air toggle speed slow (usually above 1.5 hours); The toggle speed of system of the present invention can be improved greatly; Typically, start beginning from system, the nitrogen of output 99.99% only needs 15 minutes; This has very important use meaning concerning the special equipment of some special dimensions.
Indication pressure of the present invention is gauge pressure, except as otherwise noted.
Corresponding to the above-mentioned method of in air, extracting high pure nitrogen, the present invention also proposes in air, to extract the device of high pure nitrogen.This device is by constituting like lower component:
At least include two or more adsorption towers that are filled with carbon molecular sieve;
Separate at least one and smoke vavuum pump;
At least one is optionally to each adsorption tower the supply raw materials pipeline and the necessary control valve of gas;
At least one is connected the adsorption tower feed end and is used for toxic emission, and can optionally arrange to atmosphere, carries out the normal pressure desorb and is connected pipeline and the necessary control valve that vacuum pump inlet carries out vacuum desorption with turning to;
At least one product gas surge tank, preferred but inessential an anti-oxygen migration compensator is set in addition, form the product gas surge tank together, between be connected with check valve;
At least one connects product gas surge tank and adsorption tower product end and can control pipeline and the necessary control valve that cleans flow rate;
At least one connects the adsorption tower product end and can control pipeline and the necessary control valve that material shifts between the product end;
Pipeline and necessary control valve that at least one connects product gas surge tank and adsorption tower product end and can control gas output flow rate between surge tank and the adsorption tower.
Description of drawings
Fig. 1: the high pure nitrogen process flow diagram is produced in the transformation absorption of only shifting with product end.
The specific embodiment
Further specify the inventive method and device below in conjunction with accompanying drawing.
Shown in accompanying drawing 1, raw air is communicated with feed back loop after removing airborne moisture content, oil content and solid particle through preliminary treatment, realizes the fluid switching circuit of the inventive method, and the loop is constructed as follows:
1, feed back loop is by pneumatic control valve 101A, and 101B and necessary connecting line are formed;
2, depressurized circuit is made up of pneumatic control valve 102A, 102B, 102C, 102D, muffler XYQ, vavuum pump AB02 and necessary connecting line;
3, product gas output loop is made up of pneumatic control valve 103A, 103B, 103C, check valve 103 and necessary connecting line;
4, control gas shifts and prevents loop and the parts that oxygen moves:
1) anti-block moves the scavenger circuit by pneumatic control valve 105C, check valve 105A, 105B, and necessary connecting line is formed;
2) control product end gas transfer loop is made up of pneumatic control valve 104A and necessary connecting line;
3) the compensator PV01 of the anti-block migration of oxygen absorbent is installed;
Like the pressure swing absorption process of accompanying drawing 1, also comprise two adsorption tower 01A, 01B that are filled with commercially available carbon molecular sieve, described by numerous patents in order to the pressure-swing absorption process of known technology;
Also comprise a filler special tower that is used for gas buffer and the migration of anti-block, also promptly anti-oxygen migration compensator PV01.Wherein, preferably load oxygen absorbent, the application scenario not high to some purity requirements also can be loaded like zeolite adsorbents such as commercially available 4A.During the unavoidable micropollution product end of the step that shifts at control gas; The oxygen migration at first gets into this packed tower and is adsorbed; Be reproduced and circulate to decompression phase and turn back to the carbon molecular sieve bed, effectively carried out oxygen migration protection, for the extraction of high pure nitrogen has obtained an important buffering;
Like the device of accompanying drawing, also comprise a product gas surge tank PV00;
Present embodiment is easier to understand and proposes only for convenience, does not limit the scope of application of the present invention with this.
The present invention realizes the extraction (explain that with two flow processs two adsorption towers are respectively 01A, 01B, be filled with commercially available carbon molecular sieve, circulate with 180 s half periods and carry out the transformation adsorption operations) of high-purity nitrogen through following circulation step:
When 01A is in the saturated high pressure that has when being about to switch of absorption, promptly adsorptive pressure is typical; Like 7 bar; The 01A that is about to carry out is shifted by the gas of high press to low press to 01B, and at this moment, the low pressure bed accessory has lower operating pressure; Typical in absolute pressure 70 kPa, transfer will be carried out according to following order:
1) opens and regulates feed passageway 101A control valve to suitable aperture; Gas transferring path 104A control valve to suitable aperture; The product end of 01A is communicated with the product end of 01B; The gas that 01A controls flow velocity from the 01A product end to the product end of 01B charging the time at a slow speed shifts; Such transfer result is communicated with the transfer of having carried out portion gas with the 01A product end with the 01B product end, and product end and the quilt of the later stage that control 01A shifts because of the less entering 01B bed of a large amount of oxygen that discharge of pressure reduction hangs down press absorption and less pollution product gas outlet end; This process is looked different 1～25 s of continuing of valve opening, does not drop to when not accepted in the gas transfer target components to stop.
But,, improved the adsorbent utilization rate although farthest reduced the polluted product gas port of export through the above gas transfer process of controlling; But obviously,, reclaim the energy and the product component of high-pressure tower in order to obtain the transfer of valuable gas comparatively completely; Transfer process can not be eradicated and pollute, and at this moment, system's operating sequence gets into the inhibition transition process of controlling; Flow rate to control is cleaned to the oxygen that reception tower 01B carries out adverse current, is directed against 01A simultaneously to the atmosphere release.
2) stop step 1), close 101A fully, 104A opens and regulates path 102A, and 102C control valve to suitable aperture carries out 01A to the atmosphere release; Meanwhile; Open and regulate path 103B; The 103C control valve is to suitable aperture, the gas that adsorbent therein is discharged into gas phase will and might be installed from preferred anti-oxygen migration compensator 01B is carried out preacceleration inflation, has the oxygen of trace, trace in this process usually from the gas of anti-oxygen migration compensator; More above-mentioned 1) it is higher that step is controlled the GAS QUALITY of transferring to reception tower 01B; But more relatively poor with the GAS QUALITY of product gas surge tank, discharge gas to the adsorption tower pressurising through this stage, anti-oxygen migration compensator possibly installed adsorbent therein and obtain regeneration; This process of it should be noted that also can adopt a gas buffer jar that only is provided with to realize.At this moment; The adverse current oxygen purge gas that suppresses migration is from the product gas surge tank; The adverse current oxygen cleaning process that suppresses migration has suppressed in the process that the 01B tower boosts the oxygen migration towards the trend of adsorption tower product end direction migration; This process has been created condition for the high-pure gas that is about to output, and this process is looked different 1～15 s of continuing of valve opening, rises to 50～70% o'clock of the highest adsorptive pressure and stops receiving pressure tower.
Farthest reduced adsorption tower through the above preacceleration inflation process of controlling and boosted in the process oxygen migration towards the migration trend of adsorption tower product end direction; But obviously; Equity; To just not controlling at the adsorption tower of release regeneration, this patent is then with following negative pressure desorb, and the control cleaning step is to the void tower (adsorption tower of regenerating in other words; Lower pressure column) carry out to prevent that a large amount of oxygen that discharge of adsorbent from being the control cleaning process of purpose toward the product end migration, this useful step also is able to farthest practice thrift and adopts high-purity nitrogen to carry out the regenerative process of adsorbent.As everyone knows; The gas of (perhaps being called solid phase) absorption is discharged into and (perhaps is called gas phase) in the adsorbent space and needs the time in the adsorbent; Be a dividing potential drop diffusion process, along with the reduction of oxygen partial pressure in the gas phase, the oxygen of solid phase adsorption is discharged into the speed of gas phase, speed will be accelerated; Otherwise, then become more slow.Prior art is mostly carried out the bed cleaning just in order to reduce the dividing potential drop of oxygen in the gas phase with high-pure gas such as product gas, makes adsorbent oxygen quicken to be diffused into the adsorbent gas phase, thereby is shifted out bed and make adsorbent be able to regeneration by carried away by air movement.Regenerative process is the basic of all transformation absorption, and the regeneration perfect square can be kept the starting point that adsorption system comes back to circulation, otherwise, will be a unsustainable separation process.Be understood that according to above-mentioned analysis extract desorber with vavuum pump and will obtain lower partial pressure of oxygen desorb environment, it is enough to keep the continuous release of oxygen of oxygen in the adsorbent solid phase and makes the sound regeneration of adsorbent.Research shows, the power consumption that suitable low dividing potential drop environment needs with adopt prior art to consume high-purity nitrogen to obtain low dividing potential drop regenerative environ-ment and have high cost performance, preferred; Desorption process carries out desorb near beginning immediately under the atmospheric pressure with vavuum pump basically at adsorption column pressure, and is typical, begins like 0.15 atm; Be drawn into adsorption tower always and form enough desorb dividing potential drops; Typically, like absolute pressure 30～70 kPa, and prior art generally is reduced to from the adsorption tower internal pressure and gets started the injection high-purity nitrogen when lower than regeneration gas surge tank pressure; Obviously, this will waste a large amount of high-purity nitrogens and clean.Because cleaning process is unhelpful when the tower internal pressure is higher, being in adsorption tower under the elevated pressures needs a large amount of product gas could reduce the oxygen purity in the gas phase wherein, is unprofitable to diffusion process, has wasted a large amount of product nitrogen gas; Control cleaning process of the present invention is carried out with following steps, is a kind of combined method that adopts the negative pressure desorb to clean the inhibition migration of perhaps cleaning at interval again with high-purity nitrogen earlier.
3) stop step 2); Open and regulate path 101B control valve to suitable aperture control feed flow rates; Open and regulate path 103B, 103C control valve to suitable aperture promotes and keeps 01B tower adsorptive pressure rapidly, adsorption tower 01B high speed charging absorption; The gas of absorption afterproduct end gets into back level surge tank PV01, treats to open because of check valve 103 after surge tank pressure raises to get into the product surge tank again; Meanwhile, when adsorption tower 01A pressure is reduced to atmospheric pressure, close 102C, continue to open and regulate path 102A, 102D control valve to suitable aperture extracts waste gas to absolute pressure 30～70 kPa in the tower with 01A through vavuum pump; In this step, 01A carries out vacuum desorption through external vavuum pump energy and has reduced the high-purity nitrogen consumption of cleaning usefulness to greatest extent and obtain regeneration; This process is looked different 80～150 s of continuing of valve opening, when desorber pressure is reduced to desorption pressures absolute pressure 30～70 kPa, stops.
4) continue step 3), open and regulate path 105C control valve to suitable aperture, 01A is controlled the cleaning of flow velocity, the air-flow of cleaning is because of path 102A, and the 102D control valve is opened and excluded adsorption tower 01A by vavuum pump; In this step; Gas from back level surge tank returns the cleaning process that part entering 01A carries out adverse current again; Further reduce the oxygen partial pressure in the gas phase; Thereby quicken adsorbent oxygen to be discharged into gas phase and make adsorbent obtain thoroughly regeneration along with air-flow excludes adsorption tower, 01B then continues to adsorb aerogenesis.
5) step 4) typical accommodation is to adopt at interval to clean; Through rational arrangement step 3), 4) between blanking time clean at interval realizing, this will further reduce the high purity product nitrogen of the required consumption of step 4); This by our company another not issued patents described; The cleaning process of its blanking time can be time arbitrary interval and arbitrary number of times, and purge gas is preferably from anti-oxygen migration surge tank; But do not get rid of from final products gas surge tank, collected the newly-increased surge tank of product gas before perhaps increasing in addition; This process is looked the different 5～30s of continuing of valve opening, when the thorough desorb of desorber, stops.
By above step, when step 4) finished, 01B was in the high pressure that has when approaching absorption is saturated to be about to switch; Be adsorptive pressure, typical, like 7bar; Be about to carry out 01B and shifted by the gas of high press to low press to 01A, according to the sequence of steps of as above narrating, the professional and technical personnel can understand; The pressure swing adsorption system of such operate out of phase will be formed a complete adsorption process, above-mentioned 1)～4) step is a complete half period.
Accompanying drawing 1 is described to be a technological process of only shifting with product end; But what the present invention described reduces the making nitrogen by pressure swing adsorption process of cleaning with the suitable equally band mid point of the technology of product nitrogen gas shifts or other gas shifts with the negative pressure desorption process; Its operating procedure and above-mentioned basically identical; The mid point transfer process is limited in above-mentioned control migration, carries out with the mode that is of value to product yield through the higher gas of bed purity in shifting, and replaces the step of above-mentioned respective stage.
Embodiment, Fig. 1 are the pressure swing adsorption system that shifts of product end only, according to above-mentioned specific circulation step, and pressurization absorption, negative pressure desorb; Adopt commercially available rock paddy carbon molecular sieve 600kg, in feed pressure 7bar (gauge pressure), circulation timei half period 180s; Anti-oxygen migration surge tank loads rare earth-X zeolite (a kind of oxygen absorbent) 100kg, has adopted the vavuum pump of a 7.5KW, has obtained 28Nm3/hr.; Oxygen content 1.6ppm, moisture content 2.2ppm, hydrogen, carbon dioxide, carbon monoxide, total hydrocarbon are all less than 0.1ppm; The high-purity nitrogen product, this is inconceivable in the making nitrogen by pressure swing adsorption process like known technology.
Claims (12)
1. a method of from air, extracting high-purity nitrogen is a unstripped gas with the mixed material gas that contains nitrogen and oxygen, it is characterized in that concrete steps are:
(1), will be in the saturated first adsorbent bed product end that be about to switch of absorption and be connected with the second adsorbent bed product end, the first adsorbent bed gas that will have a higher operating pressure is transferred to second adsorbent bed from product end; When wherein product end is communicated with, keep adsorbent bed charging at a slow speed, feed flow rates is 5%～80% of a normal feed flow rates at a slow speed;
(2), first adsorbent bedly stop charging, and will accomplish that gas shifts first adsorbent bed through feed end to the atmosphere release; Meanwhile, will clean and be pressurized to predetermined pressure to the second adsorbent bed oxygen that carries out adverse current from its product end, to suppress the second adsorbent bed oxygen migration away from product end from the gas of the higher degree of back level buffer system; Said back level buffer system adopts a product gas surge tank; Perhaps adopt the gas buffer jar that is connected in series more than two; Between the gas buffer jar with check valve or be connected with the programmed logic control valve, and, in a system that anti-oxygen migration compensator is installed, adsorbent is installed; This adsorbent is an oxygen absorbent, perhaps is the activated alumina adsorbents of active carbon, silica gel, activated alumina or the chemical modification of 4A zeolite, active carbon, chemical modification;
(3), to the second adsorbent bed adding unstripped gas with its pressure of rapid lifting to normal sorption pressure; Meanwhile, first adsorbent bedly, atmosphere is depressed near normal pressure through being unloaded;
(4), will unload and be pressed onto near the atmospheric first adsorbent bed vacuum desorption that carries out, get rid of the inner waste gas of bed with vavuum pump, set up certain negative pressure up to bed; Meanwhile, unstripped gas produces the higher nitrogen of concentration as product gas through second adsorption bed, gets into back level gas buffer jar and exports as product gas;
(5), continuation is got rid of the waste gas of the first adsorbent bed inside with vavuum pump, and is introduced product gas this adsorbent bed oxygen that carries out adverse current is cleaned; Meanwhile, unstripped gas produces the higher nitrogen of concentration as product gas through second adsorption bed, gets into back level gas buffer jar and exports as product gas;
Step (1)--(5) are complete half periods;
When step (5) finishes; Second adsorbent bed being in has higher operating pressure when approaching absorption is saturated to be about to switch; Be about to carry out the second adsorbent bed course, the first adsorbent bed gas and shift,, carry out the pressure-swing absorption process of an operate out of phase according to above-mentioned sequence of steps;
Repeat above-mentioned steps, promptly form a complete transformation absorption running.
2. by the described method of claim 1, it is characterized in that: the adsorptive pressure of adsorbing separation is 3～15bar.
3. by the described method of claim 1, it is characterized in that: saidly adsorbent bedly be two or more, and these beds are the out-phase operation each other.
4. by the described method of claim 1, it is characterized in that: the said adsorbent bed adsorbent that a kind of adsorb oxygen is installed at least also includes one or more in order to adsorb the pretreatment layer of other component.
5. by the described method of claim 1, it is characterized in that: said adsorbent bed have at least one arrival end and at least one port of export, arrival end also is feed end, and the port of export is also referred to as product end or non-feed end.
6. by the described method of claim 1, it is characterized in that: in the step (1) adsorbent bed stop charging and accomplish gas and shift after, the atmosphere release is adopted directly to the atmosphere release, perhaps adopt vavuum pump to extract the waste gas release.
7. by the described method of claim 1; It is characterized in that: from the gas of the higher degree of back level buffer system the adsorbent bed oxygen that carries out adverse current from its product end is cleaned and is pressurized to predetermined pressure in the step (2), its predetermined pressure be the highest adsorptive pressure 30%～90%.
8. by the described method of claim 1, it is characterized in that: in the step (3) to adsorbent bed adding unstripped gas with its pressure of rapid lifting to normal sorption pressure, method is to close being communicated with of product end and back level surge tank, perhaps toward product end conveying gas.
9. by the described method of claim 1, it is characterized in that: with vavuum pump continuous drawing bed waste gas, bed is set up the vacuum of 10～90KPa in the step (4).
10. by the described method of claim 1, it is characterized in that: it is continuous vacuumizing in step (4), (5); The product end gas purging is continuous or intermittently in the step (5), purge used product end gas and move compensator or product gas surge tank from anti-oxygen, perhaps before collected in other beds, surge tank or the pipeline of higher degree gas one or several.
11. by the described method of claim 1, it is characterized in that: when Connection Step finished between the bed, each bed layer pressure was balance or unbalanced.
12. a method according to claim 1 is extracted the device of high-purity nitrogen from the gaseous mixture that contains oxygen, nitrogen component, it is characterized in that comprising:
1) includes two or more adsorption towers that are filled with oxygen absorbent such as carbon molecular sieve at least;
2) separate and smoke vavuum pump at least one;
3) at least one is optionally to each adsorption tower the supply raw materials pipeline and the necessary control valve of gas;
4) at least one is connected the adsorption tower feed end and is used for toxic emission, and can optionally arrange and carry out the normal pressure desorb to atmosphere and be connected pipeline and the necessary control valve that vacuum pump inlet carries out vacuum desorption with turning to;
5) at least one product gas surge tank, an and anti-oxygen migration compensator is set forms the product gas surge tank together, between be connected with check valve or programme-control valve;
6) at least one connects product gas surge tank and adsorption tower product end and can control pipeline and the necessary control valve that cleans flow rate;
7) at least one connects the adsorption tower product end and can control pipeline and the necessary control valve that material shifts between the product end;
8) at least one pipeline and necessary control valve that connects product gas surge tank and adsorption tower product end and can control gas output flow rate between surge tank and the adsorption tower.
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| CN103801171B (en) * | 2014-02-14 | 2016-02-24 | 上海穗杉实业有限公司 | A kind of two-stage series connection swing adsorption oxygen generating system and method for operating thereof improving oxygen recovery rate |
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| CN106477537A (en) * | 2016-11-01 | 2017-03-08 | 北京福瑞通科技有限公司 | A kind of air-conditioned cold store nitrogen making machine and its method for producing nitrogen |
| CN110200189A (en) * | 2019-07-02 | 2019-09-06 | 池州山立分子筛有限公司 | Portable freshness-retaining device and preservation method |
| CN111467929B (en) * | 2020-04-15 | 2022-06-17 | 禁核试北京国家数据中心 | Thin gas adsorption and trapping device and adsorption and trapping process and application thereof |
| CN112279222B (en) * | 2020-11-12 | 2022-04-26 | 杭州汉德空分设备有限公司 | Pressure swing adsorption nitrogen making equipment |
| CN113184850B (en) * | 2021-05-17 | 2023-11-21 | 上海穗杉实业股份有限公司 | High-purity carbon dioxide gas purification method and device thereof |
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