CN107694284A - A kind of method of multitower displacement Vacuum Pressure Swing Adsorption concentration coal bed gas methane - Google Patents
A kind of method of multitower displacement Vacuum Pressure Swing Adsorption concentration coal bed gas methane Download PDFInfo
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Abstract
It is a kind of method of the multitower Vacuum Pressure Swing Adsorption of carbon dioxide replacement the present invention relates to low concentration coal-bed gas methane concentration technical field, it is main to include pressurization, CH4Absorption, CO2The steps such as displacement, decompression, adsorbent vacuum desorption, vacuum purging.The present invention has following advantage：Carbon dioxide is Working medium gas and recycling, methane is used as overhead product by displacement and reaches about 90% purity and 80% rate of recovery；Carbon dioxide replacement stage not pure gas of the part containing methane of discharge is, respectively, used as vacuum desorption purge gass, and after purging, purge gass are back to charging source of the gas and carbon dioxide replacement source of the gas, circulation and stress, reduction methane losses amount respectively again；Multitower series connection carries out CH4Absorption and CO2Displacement, increase the adsorbent loading of packed bed, improve methane production；Multitower is in parallel to carry out adsorbent CO2Regeneration, mobile phase pressure drop in tower is reduced, makes adsorbent reactivation easy.Present invention methane concentration suitable for the coal bed gas of different methane contents prepares the natural gas of high-quality.
Description
Technical field
The present invention relates to coal bed gas methane concentration technical field, is that a kind of multitower of carbon dioxide replacement is true specifically
The method of low-concentration methane in empty pressure-swing adsorption concentration coal bed gas.
Background technology
Methane is a kind of high-grade fuel, and reserves are big in nature, calorific value is high, and have highest hydrogen/carbon ratio, in the energy
Occupy critical role in system, be the energy more cleaned than coal and oil.Therefore, from coal bed gas, casing-head gas, shale gas, life
In thing biogas, landfill gas and the low-quality methane resource in other sources separating-purifying methane to improve energy resource structure and
Environment protection, has important practical significance and strategic importance.
China's coal bed gas resource enriches, and according to newest resources, China Coal Bed Methane Resource total amount is about 32 tcms,
It is the third-largest coal bed gas reserves state after Russia, Canada.Coal bed gas according to extraction way can be divided into ground extraction and
Underground extraction.Ground extraction can obtain CH4Fuel gas of the content more than 95%, can be directly as high-energy fuel and chemical industry
Raw material uses, but the scale is smaller of extraction at present.Underground extraction is for safety extraction coal bed gas under mine of mining, due to taking out
Large quantity of air, CH have been doped into during row4Concentration only has 10%-30%, and this part coal bed gas extraction amount is huge, every year up to
150 billion cubic meters.Due to lacking advanced practical methane concentration isolation technics, China's low concentration coal-bed gas utilization rate is only at present
The 5%-10% of total release is accounted for, the overwhelming majority is directly discharged in air, not only waste of resource, and causes serious air
Greenhouse effects (CH4Greenhouse effects are CO221 times).
It is its CH to restrict an important factor for low concentration coal-bed gas utilizes4Content is low, if by CH4Concentration improve to 80% with
On, it just can serve as high-energy fuel or industrial chemicals；If CH4Content reaches 95%, so that it may is directly incorporated into gas distributing system conveying.
Except containing a certain amount of CH in low concentration coal-bed gas4Also contain substantial amounts of CO outside2And N2And a small amount of oxygen.CO2And CH4Molecular physics
Nature difference is big, and the two is easily isolated；CH4And N2Because both kinetic diameters are close, and physical property is also similar, turns into and is most difficult to
The system of separation.Coal bed gas methane separation beneficiation technologies have cryogenic rectification, UF membrane, absorption process and absorption method etc..Absorption method by
In having the advantages that device simple, simple operation, technological process are practical and operation consumed energy is few and receive much concern, recognized
To be the technology of current low concentration coal-bed gas methane concentration most industrial prospect.
That reports at present is used for adsorbing separation CH4/N2The active charcoal of adsorbent, carbon molecular sieve, Si-Al molecular sieve, mesoporous
Molecular sieve, HTS and metal-organic framework materials.Due to existing sorbing material CH4/N2Equilibrium segregation coefficient is not high, base
In pressure swing adsorption technique it is difficult to which methane content disposably is concentrated into more than 80% below 50%.When processing methane concentration is less than
During 10% device in Gas, traditional pressure-swing adsorption concentration efficiency can be very low, and engineer applied is uneconomical.Patent (CN101549240A)
The method for introducing the absorbing methane in condensed coal bed gas through pressure varying mode of carbon dioxide replacement, is added with two in pressure-changing process flow
The step of carbonoxide displacement is adsorbed methane, makes methane turn into overhead product, so as to improve the degree of product gas methane and yield.
Relative to methane and nitrogen adsorption, carbon dioxide is strong absorbed component, and adsorbent reactivation energy consumption dramatically increases.This method does not discuss
CO 2 medium desorbs and multitower series and parallel strengthens the circulation technology of low-concentration methane enrichment.It is situated between at present on carbon dioxide
Matter desorbs and utilization process also has no other related patent reports.
The content of the invention
Therefore, the technical problem to be solved in the present invention is overcome the deficiencies in the prior art, there is provided a kind of carbon dioxide replacement
Multitower Vacuum Pressure Swing Adsorption continuously circulate concentration coal bed gas in low-concentration methane method.
The technical scheme is that a kind of vacuum pressure swing absorption process of carbon dioxide replacement, it is characterised in that use
The continuous circulation absorption of multitower, carbon dioxide replacement and vacuum desorption technology make the coal bed gas of low-concentration methane become the day of high-quality
Right gas fuel；Each circulation of methods described comprises the following specific steps that：
Step (1) is pressurizeed：Operating pressure 1.1atm~10atm that pressurization packed column to absorption phase is set；
Step (2) methane adsorption：Under 10 DEG C~50 DEG C of temperature, above-mentioned pressure condition, low concentration coal-bed gas methane is from filling out
Fill in packed column of the tower bottom of towe input containing adsorbent, carry out adsorbing and trapping methane, go out when methane adsorption forward reaches packed column
Mouthful, absorption phase terminates；
Step (3) carbon dioxide replacement：Under the conditions of 10 DEG C~50 DEG C of temperature, pressure 1.1atm~10atm, dioxy is inputted
Change carbon, replace the methane and nitrogen adsorbed in tower, as displacement is carried out, discharge gas successively from filling tower top and be separately stored in
In three surge tanks, respectively high concentration methane product gas, nitrogen-rich gas slightly slightly contain a small amount of containing a small amount of methane, high concentration methane
Carbon dioxide；In tower after methane and nitrogen displacement, packed column is substantially saturated with carbon dioxide；
Step (4) is depressured：Packed column is depressurized to normal pressure, carbon dioxide in desorber；
Step (5) vacuum desorption：Vacuumized using vavuum pump, filling tower pressure interior force is reduced to 1kPa~15kPa；So
Carbon dioxide rate can be improved.
Step (6) vacuum purging 1：Under evacuated pressure, purged, replaced in tower from tower top using a small amount of high concentration methane
Carbon dioxide；Purge gass 1 are that the high concentration methane that step (3) obtains slightly contains a small amount of carbon dioxide；
Step (7) vacuum purging 2：Under evacuated pressure, purged, replaced in tower from tower top using a small amount of nitrogen-rich gas
Methane；Purge gass 2 are that the nitrogen-rich gas that step (3) obtains slightly contains a small amount of methane.
After completing step (7), step (1) is recycled to, is repeated, carries out next circulation.
In the above-mentioned methods, in step (2), because coal bed gas methane concentration is relatively low, less than 20%, methane adsorption will be caused
Partial pressure is very low, and adsorbent methane adsorption amount is relatively low, and this technique recommends adsorbing and trapping methane with pressure, pressure be 1.1atm~
10atm, to improve methane adsorption rate.
In step (5), under conditions of vavuum pump permission, make vacuum pressure as low as possible, improve adsorbent CO2Desorption
Rate.
In step (6), high concentration methane slightly contains a small amount of carbon dioxide, from CO2Obtained in replacement process from recovered overhead
Portion gas, after vacuum purges, gas reclaims and is delivered to CO2The operation that displacement step cycle uses can reduce methane damage
Vector.
In step (7), nitrogen-rich gas slightly contains a small amount of methane, and from recovered overhead during carbon dioxide replacement
Portion gas is obtained, after purging, gas reclaims and is delivered to the use of methane adsorption step cycle, reduces methane losses amount.
According to a kind of vacuum pressure swing absorption process of carbon dioxide replacement of the present invention, it is preferred that in described multitower
The adsorbent of filling, selected from for one or both of carbon-based material and zeolite molecular sieve.
Further, adsorbent can be with the shape such as graininess, threadiness, cellular.
According to a kind of vacuum pressure swing absorption process of carbon dioxide replacement of the present invention, it is preferred that the filling of each tower
Highly it is 0.8-1.2 rice.Due to vacuum desorption, about 1 meter of the suitable packed height of each tower, to reduce pressure drop of column, improve
Desorption efficiency.
According to a kind of vacuum pressure swing absorption process of carbon dioxide replacement of the present invention, it is preferred that described is multi-tower continuous
Continuous operation is three groups or more than three groups packed column circulate operations；Every group contains single column, Liang Ta, three towers, four towers, or more tower.
Further, multitower series connection carries out CH in every group4Adsorbing and trapping and CO2Displacement；Multitower parallel connection is adsorbed in every group
Agent CO2Regeneration.
Multitower series connection carries out CH in every group4Adsorbing and trapping and CO2Displacement, improves methane production and purity, and multitower is simultaneously in every group
Connection carries out adsorbent CO2Regeneration, mobile phase pressure drop in tower is reduced, makes adsorbent reactivation easy.
According to a kind of vacuum pressure swing absorption process of carbon dioxide replacement of the present invention, it is preferred that the low concentration first
The methane concentration of alkane is 5%~20%.
According to a kind of vacuum pressure swing absorption process of carbon dioxide replacement of the present invention, it is preferred that step (3) input
Carbon dioxide is made up of two parts, is replacing early stage in stage, uses the decompression of step (4), step (5) and step (6) and Vacuum solutions
The carbon dioxide of receipts is sucked back, in the displacement later stage in stage, uses the high concentration carbon dioxide of supplement.
The carbon dioxide of step (3) input is high concentration carbon dioxide, purity more than 90%.The high concentration carbon dioxide is permitted
Perhaps contain a small amount of methane, but do not allow containing nitrogen, prevent polluted product gas methane purity.
Preferably, step (4) desorbs obtained carbon dioxide recovery and is delivered to step (3) the carbon dioxide replacement stage
Recycle；The carbon dioxide recovery of step (5) desorption is simultaneously delivered to step (3) displacement step cycle use；In step (6),
After purging, obtained carbon dioxide reclaims and is delivered to the use of step (3) carbon dioxide replacement step cycle.
Step (3) described carbon dioxide air source is made up of two parts, and displacement source of the gas early stage in stage walks from previous circulation
Suddenly the carbon dioxide reclaimed in (4), step (5) and step (6)；Displacement stage later stage source of the gas is the high-purity two newly supplemented
Carbonoxide (more than 90%).The high concentration carbon dioxide allows containing a small amount of methane, but does not allow containing nitrogen, prevents from polluting
Product gas methane purity.
According to a kind of vacuum pressure swing absorption process of carbon dioxide replacement of the present invention, it is preferred that in step (7), blow
After sweeping, gas reclaims and is delivered to step (2) recovery methane.Methane losses rate can so be reduced.
Preferably, not pure gas of the part containing methane of step (3) carbon dioxide replacement stage discharge is, respectively, used as
Vacuum desorption purge gass, after purging, purge gass 2 are back to charging source of the gas, purge gass 1 in step (2) and are back to and step (3)
Middle carbon dioxide replacement source of the gas, circulation and stress methane.
Preferably, step (5) is vacuumized using vavuum pump, filling tower pressure interior force is reduced to 5kPa~15kPa.
The beneficial effects of the invention are as follows：
Carbon dioxide replacement process of the present invention, it is divided into three parts from overhead successively, high concentration methane product gas,
Nitrogen-rich gas (slightly containing a small amount of methane) is used as follow-up vacuum purge gass 2, high concentration methane is used as (slightly containing a small amount of carbon dioxide)
Subsequently blow vacuum scavenging 1.After vacuum purging, purge gass are reclaimed, are recycled, reduce methane losses, improve methane recovery.
CH is carried out using multitower series connection in described circulation absorption technique4Adsorbing and trapping and CO2Displacement, improve methane production
And purity, multitower is in parallel to carry out adsorbent CO2Regeneration, mobile phase pressure drop in tower is reduced, makes adsorbent reactivation easy.To coal seam
Low-concentration methane (5%~20%) Adsorption Concentration efficiency is notable in gas, hence it is evident that better than traditional vacuum pressure varying adsorption technology.
Instant invention overcomes the defects of existing pressure swing adsorption, there is following advantage：1. carbon dioxide is Working medium gas
And recycle, about 10%CH4Device in Gas is made methane as overhead product and reached about by absorption and replacement process
90% purity and 80% rate of recovery；2. carbon dioxide replacement stage not pure gas of the part containing methane of discharge is, respectively, used as very
Sky desorption purge gass, after purging, purge gass are back to respectively again feeds source of the gas and carbon dioxide replacement source of the gas, circulation and stress, subtracts
Few methane losses amount；3. multiple packed column circulate operations, multitower series connection carries out CH4Adsorbing and trapping and CO2Displacement, improve methane production
Rate and purity, multitower is in parallel to carry out adsorbent CO2Regeneration, mobile phase pressure drop in tower is reduced, makes adsorbent reactivation easy.This hair
The bright methane concentration suitable for the coal bed gas of different methane contents, normal-temperature operation, can select the absorption of with pressure or near normal pressure with
CO2Displacement, the commercial sorbents such as activated carbon, zeolite, molecular sieve can use, therefore can be with relatively low cost by low methane concentrations
Coal bed gas become the gas fuel of high-quality.
Brief description of the drawings
Fig. 1 activated carbons packed column is from 10%CH4CO is carried out in coal bed gas after adsorbed methane2Tower top outflow gas is filled during displacement
Body forms and product gas and the purge gass of vacuum desorption segmentation section.
The series connection of Fig. 2 multitowers carries out low concentration CH4Adsorbing and trapping and CO2Displacement step and multitower progress adsorbent CO in parallel2Again
Raw technological process and sequencing valve schematic diagram (the first tower group example).
Seven step process circulate operation block diagrams of Fig. 3 carbon dioxide replacement Vacuum Pressure Swing Adsorption concentrating low-concentration methane.
The step CO of tri- tower groups of Fig. 4 seven2Replace the technological process signal of Vacuum Pressure Swing Adsorption enriching low-concentration coal bed gas methane
Figure.
Embodiment
Fig. 1 shows in activated carbon packed column adsorbing and trapping simulation coal bed gas and used after 10% methane in carbon dioxide replacement tower
Tower top eluting gas composition and product gas and the purge gass of vacuum desorption segmentation section are filled during the methane adsorbed, it operates pressure
Power and operation temperature are respectively nearly normal pressure and room temperature.After methane in tower and nitrogen are replaced, discharged successively from tower top, high concentration
Nitrogen slightly (present invention is used as vacuum purge gass 2) containing a small amount of methane, slightly containing a small amount of nitrogen, (present invention is recovered as producing high concentration methane
Product gas), high concentration methane slightly (present invention is used as vacuum purge gass 1) containing a small amount of carbon dioxide.It will be noted from fig. 1 that product
Gas methane purity can reach more than 90%；The gas that another two parts contain methane is used as vacuum purge gass, gas after vacuum purges
Body is back to the charging source of the gas of step (2) and the carbon dioxide replacement source of the gas of step (3) respectively, further reclaims methane, reduces
Methane losses amount.
Because methane is non-polar gas, existing adsorbent is smaller to low-concentration methane adsorption capacity, it is necessary to increase filling
Bed length (increase quantity of sorbent) improves methane production.But filling bed length increase will cause mobile phase pressure drop in tower to become
Greatly, it is unfavorable for adsorbent decompression regeneration.Therefore, the present invention intends carrying out low concentration CH using multitower series connection4Adsorbing and trapping and CO2Put
Step is changed, increase filling bed length (increase quantity of sorbent), improves methane production；Multitower is in parallel to carry out adsorbent CO2Regeneration, drop
Mobile phase pressure drop, makes CO in low tower2Adsorbent reactivation is easy, as shown in Figure 2.
Low-concentration methane method is a kind of in the carbon dioxide replacement multitower Vacuum Pressure Swing Adsorption concentration coal bed gas of the present invention
Circulation absorption, displacement and desorption technique process, each circulation includes pressurization, absorption, displacement, decompression, vacuum desorption, vacuum are blown
Sweep 1 and vacuum purge 2 seven steps (Fig. 3), its specific steps：
Step (1) is pressurizeed：
Air intake valve is opened, low-concentration methane unstripped gas is inputted, the packed column after vacuum regeneration is pressurizeed, is forced into
The adsorbing and trapping pressure of methane of setting, such as 1 to 10 atmospheric pressure, or higher.Because coal bed gas methane concentration is relatively low, cause methane
Absorption partial pressure is very low, and adsorbent methane adsorption amount is relatively low, and this technique recommends adsorbing and trapping methane with pressure.
Step (2) methane adsorption：
Air intake valve is opened, inputs low-concentration methane unstripped gas, packed column Capture by Sorbents methane, from overhead
Mainly nitrogen is, it is necessary to control methane discharge rate, to improve methane recovery in coal bed gas.If packed column carbon dioxide solution
Inhale it is insufficient, now, empty tail gas in will contain carbon dioxide, carbon dioxide is greenhouse gases, it is necessary to strictly control its discharge
Amount.
Step (3) carbon dioxide replacement：
When methane adsorption forward is bordering on tower top outlet in packed column, the valve into coal bed gas is closed, opens carbon dioxide
Intake valve, carry out the methane adsorbed in carbon dioxide replacement concentration tower.After methane and nitrogen are replaced, arranged successively from tower top
Go out, most of high concentration methane gas recovery is used as product gas, and part nitrogen-rich gas slightly contains a small amount of methane, and recovery is as follow-up true
Empty purge gass 2, part high concentration methane is slightly containing a small amount of carbon dioxide recovery as follow-up vacuum purge gass 1.Carbon dioxide replacement
It is displacement with pressure, pressure is identical with the methane adsorption trapping stage.
Step (4) is depressured
Bottom of towe air bleeding valve is opened, is depressured packed column, the carbon dioxide adsorbed in tower, is discharged from bottom of towe.Recovery
The carbon dioxide of discharge, for displacement step (3).Packed column is depressurized to nearly normal pressure, into vacuumizing desorption carbon dioxide.
Step (5) vacuum desorption
Open the valve that bottom of towe vacuumizes, the carbon dioxide adsorbed in vacuum stripper.In the condition that vavuum pump allows
Under, vacuum pressure is reduced as far as possible, improve carbon dioxide rate.
Step (6) vacuum high concentration methane purges
Under vacuumized conditions, purged using a small amount of high concentration methane from tower top, replace carbon dioxide in tower.Due to highly concentrated
It is few to spend methane gas dosage, this method obtains gas (high concentration methane using during carbon dioxide replacement from recovered overhead
Slightly contain a small amount of carbon dioxide)
Step (7) vacuum nitrogen-rich gas purges
Under vacuumized conditions, purged using a small amount of nitrogen-rich gas from tower top, methane in recovery tower.This method uses two
Gas is obtained in carbonoxide replacement process from recovered overhead (nitrogen-rich gas slightly contains a small amount of methane).
Low-concentration methane needs to use multiple adsorption tower group parallel work-flows in the continuous adsorbing and trapping coal bed gas of the present invention.Figure
4 one seven step carbon dioxide replacement vacuum of the tower group of typical case three (every group contains four towers, as shown in Fig. 2 totally ten two tower) of display become
Adsorption operations flow is pressed, each valve function and mode of operation are as shown in table 1.Seven operating procedures each circulated are divided into three phases
Deng period, predominantly CH4Absorption, CO2Displacement and CO2Desorption.Specifically, the period 1 includes pressurization and CH4Absorption, period
2 be CO2Displacement, period 3 include decompression, vacuum desorption, vacuum purging 1 and vacuum purging 2.
The CO of table 12Each adsorption tower mode of operation and sequential when replacing Vacuum Pressure Swing Adsorption enriching low-concentration coal bed gas methane
The CO of table 22Internally piloted valve in the continuous circulate operation of multitower when replacing Vacuum Pressure Swing Adsorption enriching low-concentration coal bed gas methane
Function declaration
A kind of method of the Vacuum Pressure Swing Adsorption concentration coal bed gas methane of carbonated displacement provided by the invention, overcomes
The defects of existing vacuum pressure varying adsorption technology, there is following advantage：
(1) the step of carbon dioxide replacement is adsorbed methane is added, methane is turned into overhead product, so as to improve product
The concentration and yield of gas methane.
(2) carbon dioxide is Working medium gas and recycled, that is, maintains higher key component separation, make again
Methane is as overhead product and reaches very high concentration and the rate of recovery.
(3) during carbon dioxide replacement, it is divided into three parts from overhead, nitrogen-rich gas (slightly containing a small amount of methane) is used
Product gas is collected as (slightly containing a small amount of nitrogen) in follow-up vacuum purge gass 2, high concentration methane, high concentration methane is (slightly containing a small amount of two
Carbonoxide) it is used for follow-up vacuum purge gass 1.
(4) purge gass from carbon dioxide replacement section contain methane, and after vacuum purges, gas is back to charging respectively
Source of the gas and carbon dioxide replacement source of the gas, reduce methane losses amount.
(5) multigroup packed column circulate operation, every group contains multiple packed columns.Multitower series connection carries out CH in every group4Absorption is caught
Collection and CO2Displacement, increase filling bed length (increase quantity of sorbent), improve methane production；Multitower parallel connection is adsorbed in every group
Agent CO2Regeneration, mobile phase pressure drop in tower is reduced, makes CO2Adsorbent reactivation is easy.
(6) present invention suitable for the coal bed gas of different methane contents methane concentration, normal-temperature operation, can select it is with pressure or
The nearly normal pressure absorption of person and the commercial sorbents such as displacement, activated carbon, zeolite, molecular sieve can be selected.
(7) present invention obtains methane concentration height, high income, separation condition are gentle, therefore can be with relatively low cost by low first
The coal bed gas of alkane concentration becomes the gas fuel of high-quality, and product gas can utilize pipeline, also can tinning storage.
Low-concentration methane in a kind of Vacuum Pressure Swing Adsorption concentration coal bed gas of carbon dioxide replacement of the present invention presented below
The specific embodiment of method.
Embodiment 1
Packed column filled bitumen matrix activated carbon bead, packed column diameter 27mm, packed height 0.617m, filled bitumen activity
Charcoal bead 0.1804kg.Use the packed column adsorbing and trapping methane concentration for 10% coal bed gas, to traditional vacuum pressure-variable adsorption
The experimental result of technique and carbon dioxide replacement Vacuum Pressure Swing Adsorption technique is compared as follows：
(1) traditional vacuum pressure-variable adsorption：Adsorptive pressure 150kPa, vacuum desorption pressure 5.1kPa, temperature about 298K, coal seam
Gas methane concentration is 10%, product gas methane concentration 25.3%, methane recovery 87.7%
(2) carbon dioxide replacement Vacuum Pressure Swing Adsorption：Adsorptive pressure 150kPa, vacuum desorption pressure 5.1kPa, temperature is about
298K, coal bed gas methane concentration are 10%, product gas methane concentration 83.3%, methane recovery 90.7%
Carbon dioxide replacement Vacuum Pressure Swing Adsorption will make 10% methane concentration to 83.3%, and traditional vacuum pressure-variable adsorption is only
25.3% can be concentrated to.Test result indicates that carbon dioxide replacement Vacuum Pressure Swing Adsorption has obvious advantage.
Embodiment 2
Packed column fills the cocoanut active charcoal of business, packed column diameter 27mm, packed height 0.657m, fills coconut activated
Charcoal 0.2103kg.Use the packed column adsorbing and trapping methane concentration for 10% coal bed gas, to traditional vacuum pressure swing adsorption technique
It is compared with the experimental result of carbon dioxide replacement Vacuum Pressure Swing Adsorption technique as follows：
(1) traditional vacuum pressure-variable adsorption：Adsorptive pressure 150kPa, vacuum desorption pressure 6.5kPa, temperature about 298K, coal seam
Gas methane concentration is 10%, product gas methane concentration 22.2%, methane recovery 93.0%
(2) carbon dioxide replacement Vacuum Pressure Swing Adsorption：Adsorptive pressure 150kPa, vacuum desorption pressure 13.8kPa, temperature is about
298K, coal bed gas methane concentration are 10%, product gas methane concentration 90.0%, methane recovery 82.3%
Carbon dioxide replacement Vacuum Pressure Swing Adsorption will make 10% methane concentration to 90.0%, and traditional vacuum pressure-variable adsorption is only
22.2% can be concentrated to.Test result indicates that carbon dioxide replacement Vacuum Pressure Swing Adsorption has obvious advantage.
Described above is only the preferred embodiment of the present invention, it is noted that for the ordinary skill people of the art
Member, without departing from the inventive concept of the premise, can also make some improvements and modifications, these improvements and modifications also should be regarded as
In protection scope of the present invention.
Claims (10)
1. a kind of vacuum pressure swing absorption process of carbon dioxide replacement, it is characterised in that using the continuous circulation absorption of multitower, dioxy
Changing carbon displacement and vacuum desorption technology makes the coal bed gas of low-concentration methane become the gas fuel of high-quality；Methods described it is every
Individual circulation comprises the following specific steps that：
Step (1) is pressurizeed：Operating pressure 1.1atm~10atm that pressurization packed column to absorption phase is set；
Step (2) methane adsorption：Under 10 DEG C~50 DEG C of temperature, above-mentioned pressure condition, low concentration coal-bed gas methane is from packed column
In packed column of the bottom of towe input containing adsorbent, adsorbing and trapping methane is carried out, when methane adsorption forward reaches packed column outlet, suction
The attached stage terminates；
Step (3) carbon dioxide replacement：Under the conditions of 10 DEG C~50 DEG C of temperature, pressure 1.1atm~10atm, titanium dioxide is inputted
Carbon, the methane and nitrogen adsorbed in tower is replaced, as displacement is carried out, discharge gas successively from filling tower top and be separately stored in three
In individual surge tank, respectively high concentration methane product gas, nitrogen-rich gas slightly slightly contain a small amount of two containing a small amount of methane, high concentration methane
Carbonoxide；In tower after methane and nitrogen displacement, packed column is substantially saturated with carbon dioxide；
Step (4) is depressured：Packed column is depressurized to normal pressure, carbon dioxide in desorber；
Step (5) vacuum desorption：Vacuumized using vavuum pump, filling tower pressure interior force is reduced to 1kPa~15kPa；
Step (6) vacuum purging 1：Under evacuated pressure, purged using a small amount of high concentration methane from tower top, replace dioxy in tower
Change carbon；Purge gass 1 are that the high concentration methane that step (3) obtains slightly contains a small amount of carbon dioxide；
Step (7) vacuum purging 2：Under evacuated pressure, purged using a small amount of nitrogen-rich gas from tower top, replace first in tower
Alkane；Purge gass 2 are that the nitrogen-rich gas that step (3) obtains slightly contains a small amount of methane.
2. a kind of vacuum pressure swing absorption process of carbon dioxide replacement as claimed in claim 1, it is characterised in that described is more
The adsorbent filled in tower, selected from for one or both of carbon-based material and zeolite molecular sieve.
3. a kind of vacuum pressure swing absorption process of carbon dioxide replacement as claimed in claim 1, it is characterised in that each tower
Packed height is 0.8-1.2 rice.
4. a kind of vacuum pressure swing absorption process of carbon dioxide replacement as claimed in claim 1, it is characterised in that described is more
Tower continuous operation is three groups or more than three groups packed column circulate operations, and every group contains single column, Liang Ta, three towers, four towers, or more
Tower.
5. the vacuum pressure swing absorption process of a kind of carbon dioxide replacement as described in claim 1 or 4, it is characterised in that every group
Interior multitower series connection carries out CH4Adsorbing and trapping and CO2Displacement；Multitower is in parallel in every group carries out adsorbent CO2Regeneration.
6. a kind of vacuum pressure swing absorption process of carbon dioxide replacement as claimed in claim 1, it is characterised in that described low dense
The methane concentration for spending methane is 5%~20%.
A kind of 7. vacuum pressure swing absorption process of carbon dioxide replacement as claimed in claim 1, it is characterised in that step (3)
The carbon dioxide of input is made up of two parts, displacement early stage in stage, using step (4), step (5) and step (6) be depressured and
The carbon dioxide of vacuum desorption recovery, in the displacement later stage in stage, uses the high concentration carbon dioxide of supplement.
8. a kind of vacuum pressure swing absorption process of carbon dioxide replacement as claimed in claim 7, it is characterised in that described highly concentrated
The purity for spending carbon dioxide is more than 90%.
A kind of 9. vacuum pressure swing absorption process of carbon dioxide replacement as claimed in claim 1, it is characterised in that step (3)
Carbon dioxide replacement stage not pure gas of the part containing methane of discharge is, respectively, used as vacuum desorption purge gass, after purging, blows
Scavenging 2 is back to charging source of the gas in step (2), purge gass 1 be back to carbon dioxide replacement source of the gas in step (3), be recycled back to
Receive methane.
A kind of 10. vacuum pressure swing absorption process of carbon dioxide replacement as claimed in claim 1, it is characterised in that step (5)
Vacuumized using vavuum pump, filling tower pressure interior force is reduced to 5kPa~15kPa.
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| CN118286829A (en) * | 2024-04-01 | 2024-07-05 | 上海联风气体有限公司 | Simulated moving bed operation multi-tower pressure swing adsorption process separation CH4And CO2Is a method of (2) |
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