CN103695063B - Method for concentrating low-concentration methane gas - Google Patents
Method for concentrating low-concentration methane gas Download PDFInfo
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- CN103695063B CN103695063B CN201310723718.9A CN201310723718A CN103695063B CN 103695063 B CN103695063 B CN 103695063B CN 201310723718 A CN201310723718 A CN 201310723718A CN 103695063 B CN103695063 B CN 103695063B
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Abstract
The invention discloses a method for concentrating low-concentration methane gas. According to the method, the low-concentration methane gas with the CH4 concentration not more than 30%.V and the pressure not more than 0.05 MPa.G is concentrated through a pressure swing adsorption process. The method comprises the following steps: adsorbing by N (N is not less than 3) adsorption towers, wherein each adsorption tower is filled with an adsorbent; cyclically performing N adsorption stages in an adsorption cycle, wherein N-1 serial adsorption is performed by the adsorption tower; after the N adsorption towers are serially connected and subjected to pressure equalization in each adsorption stage, washing and replacing the adsorption tower after the N-1 adsorption, vacuuming and desorbing; in addition, serially connecting the N-1 adsorption towers, reversely increasing the pressure to be the adsorption pressure, and adsorbing; repeating in the way to finish the adsorption cycle. Compared with the prior art, the method has the benefits that the CH4 yield is greatly increased, the CH4 concentration increment value is high, and the investment and running costs are low.
Description
Technical field
The present invention relates to a kind of method of extracting low-concentration device in Gas.
Background technology
China is a big coal country, and device in Gas resource is very abundant, and in China 2000m, coal seam tolerance reaches 35 tcms, suitable with land conventional gas amount.Most of CH in current China's coal-mine device in Gas
4concentration is all lower, and country's " safety regulations in coal mine " specifies CH
4concentration prohibits the use lower than the device in Gas of 30%, can only emptying process, causes the significant wastage of resource.If can fully recycle this part resource, to alleviating China energy shortage, reducing the discharge of greenhouse gases, all play significant role, of far-reaching significance.
In order to reclaim device in Gas resource as much as possible, a lot of school, R&D institution have carried out developmental research, propose multiple device in Gas concentrate CH
4method, mainly contain indirect Deep Cooling Method, catalytic oxidation, solution absorption method, pressure-variable adsorption partition method.
Indirect Deep Cooling Method: be utilize cold medium to CH
4cryogenic liquefying, and fixed gas N
2, O
2emptying, a large amount of fixed gas degree of depth cooling, causes energy consumption high, limits it in the dense use of low concentration gas air lift.Equipment manufacturing cost is high in addition, start-stop car is slow;
Catalytic oxidation: utilize CH
4and O
2react under the effect of catalyst, by the O in device in Gas
2consume, make device in Gas energy safe operation in subsequent treatment, due to CH in catalytic reaction
4also to be consumed, CH
4concentration is lower, i.e. O
2content is higher, consumes CH
4higher, CH
4yield is lower, therefore more should not adopt in low concentration gas gas is concentrated.Also CO can be produced in addition in catalytic reaction
2etc. new impurity, add the treatment step of removing impurities;
Solution absorption method: adopt absorbing liquid, absorbing and removing O
2after be applied again, this technology is also immature at present, cannot be applied in industrial production;
Pressure-variable adsorption partition method: technology is the most ripe, and simple with its flow process, automaticity is high, small investment, operating cost are low becomes unique technical method dropping into industry park plan, at CH
4-N
2in adsorbing separation, because the separation of adsorbent is lower, CH in adsorption process
4the concentration gradient formed in tower is smaller, CH in maintenance tower top absorption tail gas
4when concentration is lower, in tower, adsorbent reaches saturated just the lacking of absorption, CH in stripping gas
4content is also just lower, and at CH
4-N
2in adsorbing separation, we wish CH in absorption tail gas
4more low better, to improve CH
4yield, wishes again CH in stripping gas
4concentration is more high better, but in an adsorption tower, the two is difficult to get both, therefore many people are had to propose the pressure swing adsorption technique of multiple tandem type, as CN1140418A, CN1334135A, CN1334136A, CN1248482, CN1347747A, the patents such as CN1248482A reported, these processes are all that PSA device series connection absorption is overlapped in employing two, namely the tail gas of first set absorption overlaps the unstripped gas of absorption as second, increase to make easy adsorbent component concentration in stripping gas, easy adsorbent component concentration in absorption tail gas is just made suitably to raise, and be less than unstripped gas, after this strand of gas overlaps absorption because easy adsorbent component content is low through second, in absorption tail gas, easy adsorbent component will than only low with a set of PSA, which improves aforesaid two desired values, owing to being that two cover PSA devices run simultaneously, its investment cost must be high, operating cost is corresponding improve also.
Also people is had to propose one-step series-connected pressure swing adsorption technique for above-mentioned shortcoming, as CN1394665A, this technique is at least made up of 3 adsorption towers, as A, B, C tri-tower, if A tower is just carrying out second time absorption, unstripped gas enters by the bottom of A tower, control A column overhead in giving vent to anger easily adsorbent component to a slightly high concentration, this gas enters the B tower being in first time absorption at the bottom of tower, from B tower top easy adsorbent component concentration step-down out, reach requirement, meanwhile C tower all falls, find time, all rise, the processes such as final rise, C pressure tower is made to reach adsorptive pressure, treat A, after B series connection absorption completes, next round B can be started, C tower series connection absorption, A tower all falls, find time, all rise, final rise waited.In the process, as general pressure-swing absorption process, all fall, find time after clean tower, again by absorption relative saturation second time absorption after tower in all calmed the anger pollute, easy adsorbent component concentration exceedes and is in first time adsorption tower, and also fails to set up and adsorb corresponding concentration gradient in tower.When entering next round series connection absorption, easy adsorbent component high and the tower not setting up respective concentration gradient but enters the back segment of series connection absorption, obviously to have influence on the reduction of the easy adsorbent component of series connection absorption tail gas.
Summary of the invention
The present invention proposes a kind of method of extracting low-concentration device in Gas, solve deficiency of the prior art, use the method to carry out concentrate device in Gas gained CH
4yield significantly improves, and CH
4the increment of concentration is high, and small investment, operating cost are low.
Technical scheme of the present invention is achieved in that
A method for extracting low-concentration device in Gas, the coal mine mash gas of low pressure, low concentration adopts pressure swing adsorption technique to carry out CH by it
4concentrate, the method adopts N(N>=3) individual adsorption tower adsorbs, all adsorbent is housed in described each adsorption tower, in an adsorption cycle, N number of absorption phase is carried out in circulation altogether, in each absorption phase after N number of adsorption tower series average-voltage, carried out rinsing, replacing by the adsorption tower having carried out N-1 absorption, then N-1 the reverse adsorptive pressure that boosts to of adsorption tower series connection adsorb in addition; Then circulation like this completes an adsorption cycle.
It specifically comprises the steps:
(1) raw material device in Gas enter successively series connection absorption N-1 adsorption tower in carry out adsorbing separation, the adsorption tower that now raw material device in Gas enters at first is carrying out the N-1 time absorption, the adsorption tower finally entered be carrying out first time absorption, simultaneously to carried out on last stage adsorbing for N-1 time and complete flushing, replace tower vacuumize desorb;
(2) after the adsorbing separation in completing steps (1), N-1 adsorption tower of this series connection absorption vacuumizes the adsorption tower carrying out desorb and connects with completing, carry out N tower series average-voltage, now complete first time absorption adsorption tower in gas forward flowed into the adsorption tower vacuumizing desorb, complete second time absorption adsorption tower in gas, forward flow in the adsorption tower of first time absorption, the rest may be inferred, complete the N-1 time absorption adsorption tower in gas, has forward flowed into the N-2 time adsorb adsorption tower in;
(3) after all pressures in completing steps (2), the adsorption tower completing the N-1 time absorption with complete the adsorption tower adsorbed for the N-2 time and disconnect, and with stripping gas, the tower completing the N-1 time absorption is rinsed, replaced, simultaneously, the tower completing first time absorption with complete the adsorption tower vacuumizing desorb and connect, and boost to adsorptive pressure with N-1 the tower of absorption tail gas to series connection is reverse, now complete first absorption phase;
(4) in completing steps (3) after displacement and boosting, absorption enters second absorption phase, and to completing flushings, the adsorption tower of displacement vacuumizes desorb, carries out series connection simultaneously adsorb N-1 the tower completing reverse series boosting; Now the tower of the first time absorption of first absorption phase enters second time absorption, vacuumize the adsorption tower carrying out desorb and enter first time absorption, the tower of the N-2 time absorption of N-1 absorption phase enters the N-1 time absorption, the tower of the N-1 time absorption enters and vacuumizes desorb, through the process identical with first absorption phase, complete second absorption phase, so circulate, then complete N number of absorption phase, namely complete an adsorption cycle.
Further, when adsorbing, adsorptive pressure is 30-50KPa.
Further, described activated carbon of sorbent class adsorbent, silica type adsorbent and molecular sieve adsorbent.
Further, described adsorption tower is 3 ~ 4.
In the present invention, the adsorbent adopted is three kinds: active carbon class adsorbent, silica type adsorbent and molecular sieve adsorbent, but depending on concrete unstripped gas situation, also only two kinds of adsorbents can be adopted, three tower process processes of the present invention adopt cascade towers absorption, in an adsorption cycle, each adsorption tower respectively once will be connected with former and later two adsorption towers and be adsorbed, after each absorption completes, two towers of this series connection again with complete the tower vacuumizing regeneration and connect, carry out three tower cascade connectedly all pressing, now complete first time absorption tower in gas forward flow into vacuum column, complete second time absorption tower in gas, forward flow in the tower of first time absorption, complete after all pressing, the tower completing second time absorption with complete the first time tower that adsorbs and disconnect, and with stripping gas, the tower completing second time absorption is rinsed, displacement, the tower simultaneously completing first time absorption is connected with regenerator of finding time, and boost to adsorptive pressure with absorption tail gas is reverse.After completing displacement and boosting, desorb is vacuumized to the tower completing displacement, series connection absorption is carried out to two towers completing reverse series boosting simultaneously, now the tower of the first time absorption of first stage enters second time and adsorbs, vacuumizes that regenerator enters first time absorption, the tower of second time absorption enters and vacuumizes regeneration, absorption enters second stage, through the process identical with the first stage, completes second stage, then complete the phase III, namely complete an adsorption cycle.Circulation like this, forms a continuous print adsorption separation process.
When carrying out cascade towers absorption, allow more CH
4through last tower, make the more adsorbent of last tower reach adsorption equilibrium, make CH in tower
4content increases.And through the gas of last tower because not penetrating completely, CH
4content much smaller than material concentration, through after the adsorbing separation of a tower, just can obtain CH
4the absorption tail gas that relative concentration is lower, makes CH
4yield improves.
Three tower cascade connected after absorption is all pressed, and is that three towers join end to end, pressure equalizing CH
4completely the same when the concentration gradient formed and absorption, being conducive to adsorbing separation subsequently, and entering the gas of finding time at the bottom of regenerator tower, is CH in front two towers
4relative concentration is minimum, is conducive to controlling tail gas CH
4concentration.In the reverse series boosting of tail gas subsequently, use CH
4the absorption tail gas that content is minimum carries out reverse boosting to rear two towers that three towers are all pressed, by all pressure after the part CH found time in regenerator tower
4press at the bottom of tower, then press to the tower be attached thereto, make CH in the regenerator of finding time after all pressing
4become lower, and CH
4concentration gradient in tower is consistent with adsorption process, in equilateral triangle, and the CH of regenerator tower top of finding time
4concentration is minimum, and this to be conducive in adsorption process CH in absorption tail gas
4the reduction of concentration, thus further increase CH
4yield.
CH in absorption tail gas is wished in low concentration gas gas separating and concentrating
4concentration is more low better, to improve CH to greatest extent
4yield, to wish again to find time CH in stripping gas simultaneously
4concentration is high as far as possible, to improve CH
4enrichment multiple, be conducive to follow-up further concentrate and use.But in separation process, this two is conflict values, i.e. CH in tail gas
4concentration reduces, CH in stripping gas
4concentration also will decrease, and adopts preceding method of the present invention, can at tail gas CH
4concentration slows down CH in stripping gas of finding time when reducing
4the reduction of concentration, for improving CH in stripping gas of finding time further
4concentration, arranges again useful stripping gas to purge the tower that second adsorption completes in technical process, makes to contain O in dead space in tower
2, N
2many gaseous mixtures are displaced, the O that simultaneously also can will adsorb in adsorbent
2, N
2cemented out partially, thus made CH in stripping gas
4concentration is improved further.In processing arrangement, the exhaust gas after purging is turned back to raw material storage tank, this is no doubt reduce CH on the one hand
4loss, keeps yield, can improve CH in tower material mixed gas on the other hand
4concentration, unstripped gas CH
4concentration improves, and when other conditions are identical, can improve CH in stripping gas further
4concentration.If mixture strength can be mentioned more than 18% by the tolerance returned, gas will depart from explosive range, favourable to safety.
During resistance when raw gas pressure can overcome three tower cascade connected, four tower adsorption process can be selected, adopt three tower cascade connected absorption, a tower rinses and vacuumize the technical process of desorb, four tower series average-voltages, the reverse boosting of three tower cascade connected absorption tail gas.In this process, each adsorption tower in each adsorption cycle will complete with adjacent adsorption tower to connect for three times and adsorb, after adsorb at every turn, these three towers of connecting again with complete the tower vacuumizing desorb and connect, carry out four tower series average-voltages.Complete after all pressing, the tower completing third time absorption with complete the tower that adsorbs of second time and disconnect, and with stripping gas, the tower completing third time absorption is rinsed, displacement, the tower simultaneously completing first time absorption with vacuumize regenerator and connect, and boost to adsorptive pressure with absorption tail gas is reverse, after completing displacement and boosting, desorb is vacuumized to the tower completing displacement, three towers simultaneously completing reverse series boosting carry out series connection absorption, this process enters second stage, through the process identical with the first stage, complete second stage, then the phase III is completed, fourth stage, namely an adsorption cycle is completed, circulation like this, form a continuous print adsorption separation process.The operation of this technical process, more favourable control absorption tail gas CH
4the reduction of concentration and improve CH in stripping gas
4enrichment multiple.
Compared with prior art, the invention has the beneficial effects as follows:
(1) use the method to carry out the device in Gas of extracting low-concentration, pressure can be less than CH in the mash gas extraction gas of 50KPa
4from 5%-30% concentrate to 30%-60%, yield is greater than 90%;
(2) use the method to carry out the device in Gas of extracting low-concentration, small investment, operating cost are low.
Accompanying drawing explanation
In order to be illustrated more clearly in the embodiment of the present invention or technical scheme of the prior art, below the accompanying drawing used required in describing embodiment is briefly described, apparently, accompanying drawing in the following describes is only one of them embodiment of the present invention, for those of ordinary skill in the art, under the prerequisite not paying creative work, other accompanying drawing can also be obtained according to these accompanying drawings.
Fig. 1 is the process chart of the embodiment of the present invention one;
Fig. 2 is the process chart of the embodiment of the present invention two.
Detailed description of the invention
Be clearly and completely described the technical scheme in the present invention below, obviously, described embodiment is only several embodiments wherein of the present invention, instead of whole embodiments.Based on the embodiment in the present invention, those of ordinary skill in the art, not making the every other embodiment obtained under creative work prerequisite, belong to the scope of protection of the invention.
As depicted in figs. 1 and 2:
Embodiment 1:
In the present embodiment, adopt three adsorption towers.Adsorptive pressure is 30KPa, unstripped gas CH
4concentration is 7.7%.
The device of the 1.1 extracting low-concentration device in Gas adopted:
It comprises three adsorption towers and (is respectively the first adsorption tower 171, second adsorption tower 172,3rd adsorption tower 173), all adsorbent is housed in described each adsorption tower, the adsorbent adopted in the present embodiment is active carbon class adsorbent, silica type adsorbent and molecular sieve adsorbent, described three adsorption towers are joined end to end by pipeline and connect, the adsorption tower of head end and tail end is also joined end to end by pipeline, and be provided with sequencing valve between tower respectively and (be respectively sequencing valve 41 between the first tower on the pipeline be connected, sequencing valve 42 between the second tower, sequencing valve 43 between the 3rd tower); This device also comprises vavuum pump 8, air inlet surge tank 9, stripping gas surge tank 10 and absorption tail gas surge tank 111,
Described air inlet surge tank 9 is connected to the bottom of each adsorption tower by pipeline and is provided with air inlet sequencing valve (being respectively the first air inlet sequencing valve 11, second air inlet sequencing valve the 12, three air inlet sequencing valve 13) respectively on the pipeline connecting each adsorption tower;
Described stripping gas surge tank 10 is connected to the bottom of each adsorption tower by pipeline and is provided with stripping gas sequencing valve respectively and (is respectively the first stripping gas sequencing valve 21 on the pipeline connecting each adsorption tower, second stripping gas sequencing valve the 22, three stripping gas sequencing valve 23); And described stripping gas surge tank 10 is connected to the bottom of each adsorption tower by pipeline, and be provided with displacement gas sequencing valve respectively and (be respectively the first displacement gas sequencing valve 31 on the pipeline connecting each adsorption tower, second displacement gas sequencing valve 32,3rd displacement gas sequencing valve 33), (the first displacement gas outlet sequencing valve 61 is respectively through sequencing valve respectively from tower displacement gas out, second displacement gas outlet sequencing valve 62,3rd displacement gas outlet sequencing valve 63), enter into air inlet surge tank 9, mix with unstripped gas;
Described absorption tail gas surge tank 111 is connected to the top of each adsorption tower by twin flue and is provided with absorption tail gas sequencing valve respectively and (is respectively the first tail gas sequencing valve 71 on the pipeline connecting each adsorption tower, second tail gas sequencing valve 72,3rd tail gas sequencing valve 73) and tail gas boosting sequencing valve (be respectively first tail gas boosting sequencing valve 51, second tail gas boosting sequencing valve the 52, three tail gas boosting sequencing valve 53);
One end of described vavuum pump 8 is connected to stripping gas surge tank 10 by pipeline, its other end is connected to each adsorption tower by pipeline, and on the pipeline being connected to each adsorption tower, be provided with stripping gas sequencing valve respectively (be respectively the first stripping gas sequencing valve 21, second stripping gas sequencing valve the 22, three stripping gas sequencing valve 23).
Described air inlet surge tank 9 is connected with admission line 121.
Described stripping gas surge tank 10 is connected with stripping gas escape pipe 131, and is connected with stripping gas control valve 141 on stripping gas escape pipe 131.
Described absorption tail gas surge tank 111 is connected with absorption tail gas escape pipe 151, and is connected with absorption tail gas control valve 161 on absorption tail gas escape pipe 151.
The method that 1.2 devices applying above-mentioned extracting low-concentration device in Gas carry out extracting low-concentration device in Gas is as follows:
It adopts three adsorption towers to adsorb, in an adsorption cycle, three absorption phase are carried out in circulation altogether, in each absorption phase after three adsorption tower series average-voltages, the adsorption tower having carried out twice absorption is carried out rinsing, replacing, then vacuumize desorb, then the reverse adsorptive pressure that boosts to of two other adsorption tower series connection adsorbs; After three absorption phase have circulated, namely complete an adsorption cycle, it specifically comprises the steps:
I, first absorption phase: the first adsorption tower 171 and the second adsorption tower 172 series connection absorption; 3rd adsorption tower 173 vacuumizes desorb;
(1) cascade towers absorption and a tower vacuumize desorb: raw material device in Gas enters air inlet surge tank 9, return gas with the displacement entered to mix, the first adsorption tower 171 is entered through the first air inlet sequencing valve 11, after adsorbing separation, through between the first tower, sequencing valve 41 enters the second adsorption tower 172 again, then enters absorption tail gas surge tank 111 through the second tail gas sequencing valve 72.First adsorption tower 171 has carried out second time absorption in this stage, and the second adsorption tower 172 has carried out first time absorption.Simultaneously the 3rd stripping gas sequencing valve 23 is opened, and to be vacuumized the 3rd adsorption tower 173 by vavuum pump 8 and carry out desorb, stripping gas enters stripping gas surge tank 10, then is controlled to send by stripping gas control valve 141;
(2) three tower cascade connected all pressures: when the first adsorption tower 171, second adsorption tower 172 is connected after absorption completes, enter the first adsorption tower 171, second adsorption tower 172, the 3rd adsorption tower 173, three tower cascade connected pressure equalizing, now between the second tower, sequencing valve 42 is opened, gas sequencing valve 42 through between the second tower of the second adsorption tower 172 flows to the 3rd adsorption tower 173, simultaneously gas sequencing valve 41 through between the first tower of the first adsorption tower 171 flows to the second adsorption tower 172 and completes and all press, when all pressing end after three pressure towers balances;
Reverse boosting that (3) one towers rinse and two towers are connected: when the first adsorption tower 171, second adsorption tower 172,3rd adsorption tower 173 is three tower cascade connected all pressed after, between the first tower, sequencing valve 41 cuts out, first adsorption tower 171 is cut off with the second adsorption tower 172, the 3rd adsorption tower 173, enter that the first adsorption tower 171 rinses, replaces, reverse boost process connected by the second adsorption tower 172, the 3rd adsorption tower 173, now stripping gas is by stripping gas surge tank 10, the first adsorption tower 171 is entered, to adsorbent bedly rinsing, replacing through the first stripping gas sequencing valve 31.This gas flows out the first adsorption tower 171 through the first displacement gas sequencing valve 61 of giving vent to anger and returns air inlet surge tank 9, as the air inlet of adsorbing after mixing with unstripped gas.Absorption tail gas enters the 3rd adsorption tower 173 by absorption tail gas surge tank 111 through the 3rd absorption tail gas sequencing valve 53 simultaneously, then the second adsorption tower 172 is entered by sequencing valve 42 between the second tower, complete the second adsorption tower 172, tail gas boosting connected by the 3rd adsorption tower 173, first absorption phase terminates, and then circulates successively;
II, second absorption phase: the second adsorption tower 172 and the 3rd adsorption tower 173 series connection absorption; First adsorption tower 171 vacuumizes desorb;
III, the 3rd absorption phase: the 3rd adsorption tower 173 and the first adsorption tower 171 series connection absorption; Second adsorption tower 172 vacuumizes desorb;
After completing above-mentioned three absorption phase, namely complete an adsorption cycle, complete whole adsorption process.
Embodiment 2:
In the present embodiment, four adsorption towers are adopted to adsorb.Adsorptive pressure is 50KPa, unstripped gas CH
4concentration is 6.5%.
The device of the 2.1 extracting low-concentration device in Gas adopted:
It comprises four adsorption towers and (is respectively the first adsorption tower 171, second adsorption tower 172, 3rd adsorption tower 173, 4th adsorption tower 174), all adsorbent is housed in described each adsorption tower, the adsorbent adopted in the present embodiment is active carbon class adsorbent, silica type adsorbent and molecular sieve adsorbent, described four adsorption towers are joined end to end by pipeline and connect, the adsorption tower of head end and tail end is also joined end to end by pipeline, and be provided with sequencing valve between tower respectively and (be respectively sequencing valve 41 between the first tower on the pipeline be connected, sequencing valve 42 between the second tower, sequencing valve 43 between the 3rd tower, sequencing valve 44 between the 4th tower), this device also comprises vavuum pump 8, air inlet surge tank 9, stripping gas surge tank 10 and absorption tail gas surge tank 111,
Described air inlet surge tank 9 is connected to the bottom of each adsorption tower by pipeline and is provided with air inlet sequencing valve respectively and (is respectively the first air inlet sequencing valve 11 on the pipeline connecting each adsorption tower, second air inlet sequencing valve 12,3rd air inlet sequencing valve the 13, four air inlet sequencing valve 14), described stripping gas surge tank 10 is connected to the bottom of each adsorption tower by pipeline and is provided with stripping gas sequencing valve respectively and (is respectively the first stripping gas sequencing valve 21 on the pipeline connecting each adsorption tower, second stripping gas sequencing valve 22, 3rd stripping gas sequencing valve 23, 4th stripping gas sequencing valve 24), and described stripping gas surge tank 10 is connected to the bottom of each adsorption tower by pipeline and is provided with displacement gas sequencing valve respectively and (is respectively the first displacement gas sequencing valve 31 on the pipeline connecting each adsorption tower, second displacement gas sequencing valve 32, 3rd displacement gas sequencing valve 33, 4th displacement gas sequencing valve 34), (the first displacement gas outlet sequencing valve 61 is respectively through sequencing valve respectively from tower displacement gas out, second displacement gas outlet sequencing valve 62, 3rd displacement gas outlet sequencing valve 63, first displacement gas outlet sequencing valve 64), enter into air inlet surge tank 9, mix with unstripped gas,
Described absorption tail gas surge tank 111 is connected to the top of each adsorption tower by twin flue and is provided with absorption tail gas sequencing valve respectively and (is respectively the first tail gas sequencing valve 71 on the pipeline connecting each adsorption tower, second tail gas sequencing valve 72,3rd tail gas sequencing valve 73,4th tail gas sequencing valve 74) and tail gas boosting sequencing valve (be respectively first tail gas boosting sequencing valve 51, second tail gas boosting sequencing valve 52,3rd tail gas boosting sequencing valve the 53, four tail gas boosting sequencing valve 54);
One end of described vavuum pump 8 is connected to stripping gas surge tank 10 by pipeline, its other end is connected to each adsorption tower by pipeline, and on the pipeline being connected to each adsorption tower, be provided with stripping gas sequencing valve respectively (be respectively the first stripping gas sequencing valve 21, second stripping gas sequencing valve 22,3rd stripping gas sequencing valve the 23, four stripping gas sequencing valve 24).
Described air inlet surge tank 9 is connected with admission line 121.
Described stripping gas surge tank 10 is connected with stripping gas escape pipe 131, and is connected with stripping gas control valve 141 on stripping gas escape pipe 131.
Described absorption tail gas surge tank 111 is connected with absorption tail gas escape pipe 151, and is connected with absorption tail gas control valve 161 on absorption tail gas escape pipe 151.
The method that 2.2 devices applying above-mentioned extracting low-concentration device in Gas carry out extracting low-concentration device in Gas is as follows:
It adopts four adsorption towers to adsorb, in an adsorption cycle, four absorption phase are carried out in circulation altogether, in each absorption phase after four adsorption tower series average-voltages, the adsorption tower having carried out three absorption is carried out rinsing, replacing, then vacuumize desorb, then the reverse adsorptive pressure that boosts to of other three adsorption towers series connection adsorbs; After four absorption phase have circulated, namely complete an adsorption cycle, it specifically comprises the steps:
I, first absorption phase: the first adsorption tower 171, second adsorption tower 172 and the 3rd adsorption tower 173 series connection absorption; 4th adsorption tower 174 vacuumizes desorb:
(1) three tower cascade connected absorption and a tower vacuumize desorb: raw material device in Gas enters air inlet surge tank 9, return gas with the displacement entered to mix, the first adsorption tower 171 is entered through the first air inlet sequencing valve 11, after adsorbing separation, through between the first tower, sequencing valve 41 enters the second adsorption tower 172 again, after adsorbing separation, through between the second tower, sequencing valve 42 enters the 3rd adsorption tower 173 again, then enters absorption tail gas surge tank 111 through the 3rd tail gas sequencing valve 72.First adsorption tower 171 has carried out third time absorption in this stage, and the second adsorption tower 172 has carried out second time absorption, and the 3rd adsorption tower 173 has carried out first time absorption.Simultaneously the 4th stripping gas sequencing valve 24 is opened, and to be vacuumized the 4th adsorption tower 174 by vavuum pump 8 and carry out desorb, stripping gas enters stripping gas surge tank 10, then is controlled to send by stripping gas control valve 141;
(2) four tower series average-voltages: when the first adsorption tower 171, second adsorption tower 172 and Dang tri-adsorption tower 173 are connected after absorption completes, enter the first adsorption tower 171, second adsorption tower 172, 3rd adsorption tower 173 3 tower, with the 4th adsorption tower 174 series average-voltage process, now between the 3rd tower, sequencing valve 43 is opened, gas sequencing valve 43 through between the 3rd tower of the 3rd adsorption tower 173 flows to the 4th adsorption tower 174, gas sequencing valve 42 through between the second tower of the second adsorption tower 172 flows to the 3rd adsorption tower 173, simultaneously gas sequencing valve 41 through between the first tower of the first adsorption tower 171 flows to the second adsorption tower 172 and completes and all press, when all pressing end after three pressure tower balances,
(3) one towers rinse and three tower cascade connected reverse boosting: when the first adsorption tower 171, second adsorption tower 172, 3rd adsorption tower 173, after 4th adsorption tower 174 4 tower series average-voltage completes, between the first tower, sequencing valve 41 cuts out, make the first adsorption tower 171 and the second adsorption tower 172, 3rd adsorption tower 173, 4th adsorption tower 174 cuts off, enter the first adsorption tower 171 to rinse, displacement, second adsorption tower 172, 3rd adsorption tower 173, 4th adsorption tower 174 is connected reverse boost process, now stripping gas is by stripping gas surge tank 10, the first adsorption tower 171 is entered through the first stripping gas sequencing valve 31, rinse adsorbent bed, displacement.This gas flows out the first adsorption tower 171 through the first displacement gas sequencing valve 61 of giving vent to anger and returns air inlet surge tank 9, as the air inlet of adsorbing after mixing with unstripped gas.Absorption tail gas enters the 4th adsorption tower 174 by absorption tail gas surge tank 111 through adsorbing the 4th tail gas sequencing valve 54 simultaneously, then the 3rd adsorption tower 173 is entered by sequencing valve 43 between the 3rd tower, through between the second tower, sequencing valve 42 enters the second adsorption tower 172 again, complete the second adsorption tower 172, tail gas boosting connected by the 3rd adsorption tower 173, the 4th adsorption tower 174, first absorption phase terminates, and then circulates successively;
II, second absorption phase: the second adsorption tower 172, the 3rd adsorption tower 173 and the 4th adsorption tower 174 series connection absorption; First adsorption tower 171 vacuumizes desorb;
III, the 3rd absorption phase: the 3rd adsorption tower 173, the 4th adsorption tower 174 and the first adsorption tower 171 series connection absorption; Second adsorption tower 172 vacuumizes desorb;
IV, the 4th absorption phase: the 4th adsorption tower 174, first adsorption tower 171 and the second adsorption tower 172 series connection absorption; 3rd adsorption tower 173 vacuumizes desorb.
After completing above-mentioned four absorption phase, namely complete an adsorption cycle, complete whole adsorption process.
Embodiment 3:
In the present embodiment, three adsorption towers are adopted to adsorb.Adsorptive pressure is 40KPa, unstripped gas CH
4concentration is 12.0%, and concrete adsorption process is with embodiment 1.
Embodiment 4:
In the present embodiment, three adsorption towers are adopted to adsorb.Adsorptive pressure is 45KPa, unstripped gas CH
4concentration is 22.0%, and concrete adsorption process is with embodiment 1.
Embodiment 5:
In the present embodiment, three adsorption towers are adopted to adsorb.Adsorptive pressure is 35KPa, unstripped gas CH
4concentration is 28.0%, and concrete adsorption process is with embodiment 1.
In embodiment 1-5, adsorption conditions and result are as following table:
Wherein, CH
4increment
*(%)=stripping gas CH
4(%)-unstripped gas CH
4(%)
As can be seen from the above table, in embodiment 1-5, CH
4the equal > 90%, CH of yield
4the increment of concentration
*equal > 25%.
The foregoing is only preferred embodiment of the present invention, not in order to limit the present invention, within the spirit and principles in the present invention all, any amendment done, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.
Claims (5)
1. a method for extracting low-concentration device in Gas, is characterized in that: the coal mine mash gas of low pressure, low concentration adopts pressure swing adsorption technique to carry out CH by it
4concentrate, the method adopts N>=3 adsorption tower to adsorb, all adsorbent is housed in described each adsorption tower, in an adsorption cycle, N number of absorption phase is carried out in circulation altogether, in each absorption phase, there is N-1 adsorption tower to carry out series connection absorption, another tower vacuumizes desorb, thereafter the series average-voltage of N number of adsorption tower is carried out, after all having pressed, the adsorption tower having carried out N-1 absorption is rinsed, displacement, then N-1 the reverse adsorptive pressure that boosts to of adsorption tower series connection adsorb in addition, to completing flushing, the adsorption tower of displacement vacuumizes desorb, enter second absorption phase, circulation like this N time, complete an adsorption cycle.
2. the method for a kind of extracting low-concentration device in Gas according to claim 1, is characterized in that: it specifically comprises the steps:
(1) raw material device in Gas enter successively series connection absorption N-1 adsorption tower in carry out adsorbing separation, the adsorption tower that now raw material device in Gas enters at first is carrying out the N-1 time absorption, the adsorption tower finally entered be carrying out first time absorption, simultaneously to carried out before adsorbing for N-1 time and complete flushing, replace tower vacuumize desorb;
(2) after the adsorbing separation in completing steps (1), N-1 adsorption tower of this series connection absorption vacuumizes the adsorption tower carrying out desorb and connects with completing, carry out N tower series average-voltage, now complete first time absorption adsorption tower in gas forward flowed into the adsorption tower vacuumizing desorb, complete second time absorption adsorption tower in gas, forward flow in the adsorption tower that once adsorbs, the rest may be inferred, complete N-1 time absorption adsorption tower in gas, has forward flowed into N-2 time adsorb adsorption tower in;
(3) after all pressures in completing steps (2), the adsorption tower completing N-1 absorption with complete the adsorption tower adsorbed for N-2 time and disconnect, and with stripping gas, the tower completing N-1 absorption is rinsed, replaced, simultaneously, the tower completing first time absorption vacuumizes the adsorption tower carrying out desorb and connects with completing, and boost to adsorptive pressure with N-1 the tower of absorption tail gas to series connection is reverse, now complete first absorption phase;
(4) in completing steps (3) after displacement and boosting, absorption enters second absorption phase, and to completing flushings, the adsorption tower of displacement vacuumizes desorb, carries out series connection simultaneously adsorb N-1 the tower completing reverse series boosting; Now the tower of the first time absorption of first absorption phase enters second time absorption, vacuumize the adsorption tower carrying out desorb and enter first time absorption, the tower of the N-2 time absorption enters the N-1 time absorption, the tower before carrying out the N-1 time absorption enters and vacuumizes desorb, through the process identical with first absorption phase, complete second absorption phase, so circulate, then complete N number of absorption phase and namely complete an adsorption cycle.
3. the method for a kind of extracting low-concentration device in Gas according to claim 1 and 2, is characterized in that: when adsorbing, and adsorptive pressure is 30-50KPa.
4. the method for a kind of extracting low-concentration device in Gas according to claim 1 and 2, is characterized in that: described adsorbent is active carbon class adsorbent, silica type adsorbent and molecular sieve adsorbent.
5. the method for a kind of extracting low-concentration device in Gas according to claim 1 and 2, is characterized in that: described adsorption tower is 3 ~ 4.
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