CN102489120A - Low temperature methanol wash method and equipment - Google Patents
Low temperature methanol wash method and equipment Download PDFInfo
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- CN102489120A CN102489120A CN201110404391XA CN201110404391A CN102489120A CN 102489120 A CN102489120 A CN 102489120A CN 201110404391X A CN201110404391X A CN 201110404391XA CN 201110404391 A CN201110404391 A CN 201110404391A CN 102489120 A CN102489120 A CN 102489120A
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Abstract
The invention discloses a low temperature methanol wash method and equipment, wherein the method comprises an absorption step, a desorption step and a methanol heat regeneration step. The absorption step further comprises: adopting first lean methanol solution to absorb virgin gas for the first time, and cooling to form first rich methanol solution; forming first gas and first liquid after gas-liquid separation; adopting second lean methanol solution to absorb the first gas for a second time, and forming second absorbed rich methanol solution after the second lean methanol solution is absorbed for a second time; carrying out flash distillation on the second absorbed rich methanol solution to form second gas and flash distillated rich methanol solution; and adopting third lean methanol solution to absorb the second gas for a third time, forming third gas and reflux rich methanol solution, and respectively recycling the third gas and the reflux rich methanol solution. The method can be high-efficient, flexible, safely and energy-saving to treat carbonyl gas with different pressures, temperatures, moisture contents and sulphur concentrations.
Description
Technical field
The present invention relates to the field that coal gas body, natural gas and other carbonyl gas purify, handle and reclaim, especially relate to a kind of low-temperature rectisol method and apparatus.
Background technology
Low-temp methanol washing process is the exploitation fifties in last century and drops into the process for purifying of industry production, mainly is that being used to purify with coal, water-coal-slurry, slag or heavy oil is the synthesis gas that raw material is produced.At present, low-temp methanol washing process has been widely used in producing in the gas purifying technique process of synthetic ammonia, synthesizing methanol, coal preparing natural gas, town gas, industrial hydrogen production etc.
In Fig. 1, provided a kind of existing low-temp methanol washing process flow process, comprised the step of absorption, desorb and the regeneration of methyl alcohol heat, below will further specify the situation of low-temp methanol washing process in the prior art with reference to Fig. 1.
Step (one), absorption step: adopt poor methanol solution that unstripped gas 28 is carried out GAS ABSORPTION and discharges purified gas, a kind of comparatively concrete step is following:
As shown in Figure 1; Adopt 30 pairs of unstripped gas of the first poor methanol solution 28 to carry out absorbing the first time, form gas-liquid mixture, this gas-liquid mixture is after subcooler 1 is cooled to predetermined temperature; Form the first rich methanol solution 34; This first rich methanol solution 34 gets into gas-liquid separator 2, in gas-liquid separator 2, behind the separating and dehydrating, generates first gas and first liquid 36.First liquid 36 is deviate from water through the methanol-water knockout tower 27 in the hot regeneration step of methyl alcohol, reclaims behind the generation methanol steam.
First gas gets into methanol wash tower 4, and methanol wash tower 4 comprises the decarbonization section 4a and the hypomere desulfurization section 4b that is positioned at tower of the epimere that is positioned at tower.First gas gets into the 4 second poor methanol solution, the 51 reverse convection current back and under methanol wash tower 4 overhead streams of methanol wash tower and contacts; This first gas gets into the epimere decarbonization section 4a of tower after desulfurization is handled at desulfurization section 4b; And after carbonization treatment, form purified gas 39 at decarbonization section 4a, reclaim after purified gas 39 condensations.
In above-mentioned methanol wash tower 4, the second poor methanol solution 51 forms the second rich methanol solution at decarbonization section 4a after carbonization treatment, and the first 43 in the second rich methanol solution forms the 3rd rich methanol solution 38 after desulfurization is handled in desulfurization section 4b.
The second portion 42 of the second rich methanol solution flow in first flash tank 8, is separated through solution-air, forms A part second gas 31 and A part flash distillation rich methanol solution 45 (promptly not having sulphur rich methanol solution 45).The 3rd rich methanol solution 38 flow in second flash tank 7, is separated through solution-air, forms B part second gas and B part flash distillation rich methanol solution 46 (being sulfur-bearing rich methanol solution 46).A part second gas 31 merges into second gas 37 with B part second gas and is back in the gas-liquid mixture as circulating air 29 through recycle gas compressor 3 compression superchargings.
Step (two), desorption procedure: desorb does not have gas in sulphur rich methanol solution 45 and the sulfur-bearing rich methanol solution 46, and a kind of comparatively concrete step is following:
No sulphur rich methanol solution 45 (being A part flash distillation rich methanol solution 45) is divided into 2 strand 48 of 1 strand 49 of no sulphur rich methanol solution A and no sulphur rich methanol solution A, 1 strand of 49 inflow of no sulphur rich methanol solution A CO
2The top of product tower 9, no sulphur rich methanol solution A flows into H for 2 strand 48
2The top of S concentration tower 10, same, sulfur-bearing rich methanol solution 46 (being B part flash distillation rich methanol solution 45) is divided into 2 strand 50 of 1 strand 47 of sulfur-bearing rich methanol solution B and sulfur-bearing rich methanol solution B, and sulfur-bearing rich methanol solution B flows into CO for 1 strand 47
2The middle part of product tower 9, sulfur-bearing rich methanol solution B flows into H for 2 strand 50
2The middle part of S concentration tower 10.Flow into H
22 strand 48 of no sulphur rich methanol solution A in the S concentration tower 10 and sulfur-bearing rich methanol solution B further expand for 2 strand 50, and desorb generates the 4th rich methanol solution 53, the four rich methanol solution 53 through pump 15 extractions after going out gas, flow into CO after the intensification
2The lower end of product tower 9 is at CO
2Product tower 9 is separated a large amount of CO of dissolving in the sucking-off solution
2Behind the gas, and through CO
2No sulphur rich methanol solution A after 9 desorbs of product tower is converged formation the 5th rich methanol solution 57, the five rich methanol solution 57 for 1 strand 47 with sulfur-bearing rich methanol solution B for 1 strand 49 and is flow into H
2S concentration tower 10 hypomeres are at H
2The lower end of S concentration tower 10 feeds low-pressure nitrogen 59 gases and makes CO
2Take off suction, reach H
2Generate the 6th rich methanol solution 58 after the purpose that the S quilt concentrates.
At CO
2Separate the CO of sucking-off in the product tower 9
240 from CO
2The top of product tower 9 is discharged the back cooling, is reclaimed.At H
2Gas and the low-pressure nitrogen 59 of separating sucking-off in the S concentration tower 10 get into H through rising the gas plate
2S concentration tower epimere after 2 strand of 48 desulfurization of no sulphur rich methanol solution A with cat head, forms tail gas 41 from H
2S concentration tower cat head flows out, and enters atmosphere after the condensation.
Above-mentioned the 4th rich methanol solution 53 can through with regeneration after the second rich methanol liquid 42 of poor methanol solution 52, second portion carry out the heat exchange back of heating up and get into CO
2Product tower 9 bottoms.
Step (three), the hot regeneration step of methyl alcohol, a kind of comparatively concrete step is following:
Above-mentioned the 6th rich methanol solution 58 is from H
2After flow out S concentration tower 10 bottoms; After pressurizeing, heating, flow in the hot regenerator 19 of methyl alcohol; The step of in Fig. 1, pressurizeing is accomplished through first feed pump 11 and second feed pump 17, and the step of heating can be through carrying out the temperature displacement with poor methanol solution 68 in the first poor methanol cooler 12 and the second poor methanol cooler 14.After above-mentioned the 6th rich methanol solution 58 flow into the hot regenerator 19 of methyl alcohol, the methanol steam that produces through tower bottom reboiler, and from the methanol steam stripping of methanol-water knockout tower 27, to contained H in the 6th rich methanol solution 58
2S and CO
2Carry out complete desorb, generate reflux gas and cold methanol solution 68.
Above-mentioned reflux gas is through cooling, gas-liquid separation, cooling again, a part is sent to Sulfur Recovery Unit workshop section as sour gas 65 after re-heat after the gas-liquid separation again, and a part feeds H as circulating air
2The bottom of S concentration tower 10.Reflux gas forms first reflux gas 63 and first withdrawing fluid 69 in knockout drum 21 after condenser 20 coolings in Fig. 1; First withdrawing fluid 69 is pumped through pump 22 and is flow back in the hot regenerator 19 of methyl alcohol; First reflux gas 63 is after cool exchanger 23 and ammonia cooler 24 cool off once more; Flow into gas-liquid separator 25, separate forming second reflux gas 64 and second withdrawing fluid 154.Second withdrawing fluid 154 is back to H
2The bottom of S concentration tower 10, second reflux gas 64 is divided into two parts, and a part 65 is sent to Sulfur Recovery Unit workshop section, and a part 155 feeds H as circulating air
2The bottom of S concentration tower 10.
A poor methanol solution part that flows out from the hot regenerator of methyl alcohol 19 bottoms extracts through pump 18; Use as poor methanol at the top that after the second poor methanol cooler 14, the first poor methanol cooler 12 and 5 coolings of the 3rd poor methanol cooler, is back to methanol wash tower 4; Another part flow in the methanol-water knockout tower 27; Carry out gas-liquid separation; The methanol steam 62 that in methanol-water knockout tower 27, is produced is back in the hot regenerator 19 of methyl alcohol, the 6th rich methanol 58 in the hot regenerator 19 of methyl alcohol is carried out gas carry, and remaining moisture 66 is got rid of.
Can find out that from above-mentioned low-temp methanol washing process flow process generally speaking, methanol cleaning process comprises following three parts, i.e. absorption, desorb and the regeneration of methyl alcohol heat.Wherein, the main purpose of absorption is with COS, CO
2And H
2S is dissolved in the methyl alcohol, in this process, and a considerable amount of H
2, CO also can be absorbed simultaneously.Therefore, can be through middle pressure flash distillation with partly soluble H
2, CO, from absorption liquid, discharge.Generally, pressure is low more in the middle pressure flash distillation 7,8, H
2, CO the rate of recovery also high more, still, the CO that is discharged in the low more rich methanol solution of pressure
2Amount also increase severely, thereby the energy consumption of recycle gas compressor 3 also will increase severely.Meanwhile, a large amount of CO that discharged
2Import once more after the supercharging in the unstripped gas, in main absorption tower 4, reuptaked, this has also just increased the gas phase load on main absorption tower 4, and the increase of poor methanol 51 internal circulating loads that adapt with it.
Therefore, in order further not increase the energy consumption of device, after business accounting and optimizing, existing low-temp methanol washing process has to abandon improve H through pressing the means of flashing pressure in the further reduction
2, the CO rate of recovery plan, otherwise, reclaim the benefit that available gas brought, all can support not Shang therefore and the cost of the energy of increase consumption.Pressure generally is controlled at about 1.7MPa in the existing flash tank.So the rate of recovery of purified gas, particularly CO generally can only arrive about 98%.
Summary of the invention
The object of the present invention is to provide a kind of method and apparatus of low-temperature rectisol, to improve the rate of recovery of purified gas.
For this reason; The invention provides a kind of low-temp methanol washing method, comprise the step of absorption, desorb and the regeneration of methyl alcohol heat, the step that wherein absorbs further comprises: adopt the first poor methanol solution that unstripped gas is carried out absorbing the first time; Form gas-liquid mixture, form the first rich methanol solution through cooling; The first rich methanol solution is carried out gas-liquid separation handle, form first gas and first liquid; Adopt the second poor methanol solution that first gas is carried out absorbing the second time, first gas forms purified gas after absorbing for the second time, and reclaim the cooling back, and the second poor methanol solution forms secondary and absorbs rich methanol solution after absorbing for the second time; Secondary is absorbed rich methanol solution carry out flash distillation, form second gas and flash distillation rich methanol solution; Adopt the 3rd poor methanol solution that second gas is absorbed for the third time, generate the 3rd gas and backflow rich methanol solution, the 3rd gas flows in the gas-liquid mixture as circulating air; Backflow rich methanol solution refluxes and with the said second poor methanol solution (51) said first gas is carried out absorbing the second time.
Further; Adopt the second poor methanol solution that the step that first gas carries out absorbing is for the second time further comprised in the above-mentioned methanol washing method: to adopt the second poor methanol solution and the reverse convection current of first gas; First gas is carried out desulfurization, carbonization treatment to form purified gas, wherein: the second poor methanol solution is flowing through desulfurization section formation second rich methanol solution after desulfurization is handled; The first of the second rich methanol solution flows through decarbonization section and after carbonization treatment, forms the 3rd rich methanol solution; The step of secondary absorption rich methanol solution being carried out flash distillation further comprises: second portion in the second rich methanol solution is carried out flash distillation, form A part second gas 31 and A part flash distillation rich methanol solution; The 3rd rich methanol is carried out flash distillation, form B part second gas and B part flash distillation rich methanol solution; A part flash distillation rich methanol solution and B part flash distillation rich methanol solution are transported to stripping apparatus and the hot reclaim equiment of methyl alcohol carries out the processing of desorb and the regeneration of methyl alcohol heat, and converge A part second gas 31 and form second gas with B part second gas.
Further; Adopt the 3rd poor methanol solution that the step that second gas absorbs is for the third time further comprised in the above-mentioned methanol washing method: adopting temperature is that-45～-65 ℃, pressure are that the 3rd poor methanol and second gas of 1.2～2.0MPa absorbs, and forms the 3rd gas and backflow rich methanol solution.
Further, the step that in the above-mentioned methanol washing method backflow rich methanol solution is refluxed further comprises: backflow rich methanol solution is carried out supercharging, be pressurized to backflow desulfurization section 4b behind 2.8～8.5MPa.
Further, the first poor methanol solution, the second poor methanol solution and the 3rd poor methanol solution all adopt the poor methanol solution that generates in the step by the regeneration of methyl alcohol heat through supercharging and after heating up in the above-mentioned methanol washing method.
Further, the 3rd poor methanol solution is that the poor methanol that is generated in the step by the regeneration of methyl alcohol heat is pressurized to 1.2～2.0MPa through first supercharging device in the above-mentioned methanol washing method, simultaneously, is cooled to-45～-65 ℃ of formation through at least one poor methanol cooler.
Further, the input amount of the 3rd poor methanol solution is 0.5～4.3% of the total input amount of first, second, third poor methanol solution in the above-mentioned methanol washing method.
Further, in the above-mentioned methanol washing method in the backflow rich methanol solution molar concentration of CO2 be 0.1～0.60%.
Further, in the above-mentioned methanol washing method second portion second rich methanol and/or the 3rd rich methanol are carried out in the step of flash distillation, flashing pressure is 1.2-1.7MPa.
Simultaneously; A kind of low-temperature rectisol equipment of using said method also is provided in the present invention; Comprise the gas absorbing device, gas desorption device and the hot regenerating unit of methyl alcohol that are linked in sequence; Gas absorbing device comprises: cooler is used to cool off through the first poor methanol solution that absorbs for the first time and the mixture of unstripped gas and forms the first rich methanol solution; First gas-liquid separator is used for that the first rich methanol solution is carried out gas-liquid separation and handles, and forms first gas and first liquid; The methanol wash tower is used to adopt the second poor methanol solution that first gas is carried out absorbing the second time, forms purified gas and secondary and absorbs rich methanol solution; Low-temperature rectisol equipment also comprises CO
2The absorption tower, CO
2The absorption tower is arranged between methanol wash tower and the gas desorption apparatus, comprising: flash tank, comprise tank body, and tank body is provided with first outlet that is positioned at the top, second outlet that is positioned at the bottom, and is positioned at the inlet of first on the sidewall; First inlet link to each other with the outlet of methanol wash tower, second export and to link to each other with the gas desorption device; Packed tower; Comprise the filler heap that tower body is inner with being positioned at tower body, tower body is provided with first gas access that is positioned at the bottom of the tower, is positioned at first gas vent of cat head; First liquid outlet between first gas access and filler heap; And first liquid inlet between first gas vent and filler heap, first liquid inlet link to each other with the poor methanol delivery device, first liquid outlet links to each other with the inlet of methanol wash tower; Rise gas cap, link to each other with first gas access with first outlet respectively, gas phase is communicated with flash tank and packed tower.
Beneficial effect of the present invention: regeneration low-temperature rectisol method and apparatus provided by the present invention, can adopt the low temperature poor methanol to absorb a large amount of CO in the resulting circulating air after flash distillation
2Gas has been realized handling different pressures, temperature, water content efficient, flexible, safely, energy-conservation, and the carbonyl gas of sulphur constituent concentration, can make: total sulfur＜0.1ppm, CO
2The purified gas that＜10ppm is fixed according to the purposes of purified gas.Under the prerequisite that significantly reduces equipment power dissipation, increased the rate of recovery of effective gas widely simultaneously, wherein: the rate of recovery of CO also can reach more than 99.5%.
Except top described purpose, feature and advantage, the present invention also has other purpose, feature and advantage.To do further detailed explanation to the present invention with reference to figure below.
Description of drawings
Accompanying drawing constitute this specification a part, be used for further understanding the present invention, accompanying drawing shows the preferred embodiments of the present invention, and is used for explaining principle of the present invention with specification.Among the figure:
Fig. 1 shows the low-temp methanol washing process flow chart according to prior art, wherein shows the low-temperature rectisol equipment of prior art;
Fig. 2 shows the CO according to the embodiment of the invention
2Absorption tower structure schematic diagram;
Fig. 3 shows the low-temp methanol washing process flow chart according to the embodiment of the invention, wherein shows the low-temperature rectisol equipment of the embodiment of the invention.
The specific embodiment
Below in conjunction with accompanying drawing embodiments of the invention are elaborated, but following embodiment and accompanying drawing only are in order to understanding the present invention, and can not limit the present invention, the multitude of different ways that the present invention can be defined by the claims and cover is implemented.
In a kind of typical mode of the present invention; A kind of low-temp methanol washing method; The step that comprises absorption, desorb and the regeneration of methyl alcohol heat; The step that wherein absorbs further comprises: adopt 30 pairs of unstripped gas of the first poor methanol solution 28 to carry out absorbing the first time, form gas-liquid mixture, form the first rich methanol solution 34 through cooling; The first rich methanol solution 34 is carried out gas-liquid separation handle, form first gas and first liquid 36; The methanol-water knockout tower 27 that first liquid 36 is back in the hot regeneration step of methyl alcohol is deviate from water, reclaims behind the generation methanol steam.Adopt 51 pairs first gases of the second poor methanol solution to carry out absorbing the second time, first gas forms purified gas 39 after absorbing for the second time, and reclaim the cooling back, and the second poor methanol solution 51 forms secondary and absorbs rich methanol solution after absorbing for the second time; Secondary is absorbed rich methanol solution carry out flash distillation, form second gas and flash distillation rich methanol solution; Flash distillation rich methanol solution is transported to the processing that stripping apparatus and the hot reclaim equiment of methyl alcohol carry out desorb and the regeneration of methyl alcohol heat; Adopt 104 pairs second gases of the 3rd poor methanol solution to absorb for the third time, generate the 3rd gas 37 and backflow rich methanol solution, the 3rd gas 37 flows in the gas-liquid mixture cycling and reutilization as circulating air; Backflow rich methanol solution is back in the step that absorbs for the second time and with the second poor methanol solution 51 first gas is carried out absorbing cycling and reutilization the second time.
Adopt the low temperature poor methanol to absorb a large amount of CO in the resulting circulating air after flash distillation through increasing in the present invention
2The step of gas has realized handling different pressures, temperature, water content efficient, flexible, safely, energy-conservation, and the carbonyl gas of sulphur constituent concentration, can make: total sulfur＜0.1ppm, CO
2The purified gas that＜10ppm is fixed according to the purposes of purified gas.Under the prerequisite that significantly reduces equipment power dissipation, increased the rate of recovery of effective gas widely simultaneously, wherein: the rate of recovery of CO also can reach more than 99.5%.
In a kind of concrete embodiment of the present invention; The step that adopts 51 pairs first gases of the second poor methanol solution to carry out absorbing for the second time in the above-mentioned low-temp methanol washing method further comprises: adopt 51 pairs first reverse convection current of gas of the second poor methanol solution, first gas is carried out generating purified gas after desulfurization, the carbonization treatment.The second poor methanol solution 51 is flowing through desulfurization section 4b formation second rich methanol solution after desulfurization is handled.The first 43 of the second rich methanol solution flows through decarbonization section 4a and after carbonization treatment, forms the 3rd rich methanol solution 38; The step of secondary absorption rich methanol solution being carried out flash distillation further comprises: the second portion 42 to the second rich methanol solution carries out flash distillation, forms A part second gas 31 and A part flash distillation rich methanol solution; The 3rd rich methanol 38 is carried out flash distillation, form B part second gas and B part flash distillation rich methanol solution; A part flash distillation rich methanol solution and B part flash distillation rich methanol solution are transported to stripping apparatus and the hot reclaim equiment of methyl alcohol carries out the processing of desorb and the regeneration of methyl alcohol heat, and converge A part second gas 31 and form second gas with B part second gas.
This mode is adapted to methanol wash tower 4 in the prior art and comprises decarbonization section 4a that is positioned at scrubbing tower 4 epimeres and the situation that is positioned at the desulfurization section 4b of scrubbing tower 4 hypomeres; At this moment; The system that is used for the step that this methanol washing method absorbs comprises two loops, and loop 1 is that the second poor methanol solution 51 absorbs CO in first gas
2Generate the second rich methanol solution, the second rich methanol second portion 42 is carried out flash distillation, form A part second gas 31 and A part flash distillation rich methanol solution; Generate the 3rd rich methanol 38 behind the sour gas in first's 43 further absorption first gases of the second rich methanol solution and carry out flash distillation, form B part second gas and B part flash distillation rich methanol solution; A part second gas 31 converges back the inflow in the gas-liquid mixture with B part second gas and recycles, and is back in the desulfurization treatment step behind A part flash distillation rich methanol solution and the B part flash distillation rich methanol solution bout to recycle.
Preferably; The step that adopts 104 pairs second gases of the 3rd poor methanol solution to absorb for the third time further comprises: adopting temperature is that-45～-65 ℃, pressure are that the 3rd poor methanol solution 104 and second gas of 1.2～2.0MPa carries out GAS ABSORPTION, generates the 3rd gas and backflow rich methanol solution.In this temperature range, solution C O effectively
2, avoid the reduction of reason in operating pressure, and cause since methyl alcohol to CO
2The reduction of solvability, and the amount through the methanol solution (102) that increases of having to compensates the situation of the amount that its solvability descends.In this pressure limit, help increasing the mobile of the 3rd poor methanol 104 and helping the CO that the 3rd poor methanol 104 absorbs in second gas
2
Preferably, backflow rich methanol solution is transported in the methanol wash tower 4, the step of cycling and reutilization further comprises: backflow rich methanol solution is carried out supercharging, be back in the step of desulfurization section 4b after being pressurized to 2.8～8.5MPa.Backflow rich methanol solution is carried out supercharging, help overcoming the resistance in downstream, the rich methanol solution of being convenient to reflux is back to desulfurization section, in order to said second gas sweetening.
Preferably, the above-mentioned first poor methanol solution 30, the second poor methanol solution 51 and the 3rd poor methanol solution 104 all adopt the poor methanol that generates in the step of the methyl alcohol heat regeneration after supercharging and cooling.This mode can realize recycle, reduces to consume.
Preferably; Above-mentioned the 3rd poor methanol solution 104 is that the poor methanol solution 68 that is generated in the step by the regeneration of methyl alcohol heat is pressurized to 1.2～2.0MPa through first supercharging device 100; Simultaneously, be cooled to-45～-65 ℃ of formation through at least one poor methanol cooler 14,12,5.Directly use the stable operation that helps operating after will and being cooled to required condition by the poor methanol supercharging that is generated in the hot step of regenerating of methyl alcohol.
Poor methanol cooler 14,12,5 can be the poor methanol heat exchanger, and this poor methanol heat exchanger can carry out heat exchange with the rich methanol solution that is generated in poor methanol solution that is generated in the hot step of regenerating of methyl alcohol and the desorption procedure.Utilize system thermal repeatedly from the mode that heats up like this, can reduce energy consumption significantly.
Preferably, the input amount of above-mentioned the 3rd poor methanol solution 104 is 0.5～4.3% of the total input amount of first, second, third poor methanol solution.The input amount of the 3rd poor methanol solution is not limited in this scope, and the input amount of the 3rd poor methanol is too high can to increase the equipment that is adopted when absorbing for the second time, the burden of methanol wash tower 4 just, and input amount is low excessively, can reduce for the third time CO in the absorption process
2Uptake, the input amount of the 3rd poor methanol solution is controlled to be 0.5～4.3% of the total input amount of first, second, third poor methanol solution, help the stable operation of this methanol washing method.
Preferably, CO in the above-mentioned backflow rich methanol solution 106
2Molar concentration be 0.1～0.60%.CO in this backflow rich methanol solution 106
2Molar concentration be not limited to this, but with CO
2Molar concentration be set in this scope, help making the stable operation of this methanol washing method.
Preferably, above-mentioned second portion second rich methanol 42 and/or the 3rd rich methanol 38 are carried out in the step of flash distillation, flashing pressure is 1.2-1.7MPa.Flashing pressure is not limited in this scope in this methanol washing method; Also can access good application when being higher than 1.7MPa; But with flashing pressure is that the rate of recovery that helps improving the rate of recovery, particularly CO of effective purified gas in the 1.2-1.7MPa scope can reach more than 99.5%.
In a kind of exemplary embodiment of the present invention; A kind of methyl alcohol of using above-mentioned methanol washing method is washed equipment; Comprise the gas absorbing device that is linked in sequence, gas desorption device and the regeneration of methyl alcohol heat; Gas absorbing device comprises: cooler 1 is used to cool off the first rich methanol solution 34 that the mixture of the first poor methanol solution 30 and unstripped gas 28 forms; First gas-liquid separator 2 is used for that the first rich methanol solution 34 is carried out gas-liquid separation and handles, and forms first gas and first liquid 36; Methanol wash tower 4 is used to adopt 51 pairs first gases of the second poor methanol solution to carry out absorbing the second time, forms purified gas and secondary and absorbs rich methanol solution; This methyl alcohol is washed equipment and is also comprised: CO
2Absorption tower 70, it is arranged between methanol wash tower 4 and the gas desorption apparatus.This low-temperature rectisol equipment provided by the present invention can utilize low temperature poor methanol solution absorption a large amount of CO in the resulting circulating air after flash distillation through increasing by one
2The equipment of gas, so can be efficiently, flexibly, safety, energy-conservation handle different pressures, temperature, water content, and the carbonyl gas do not limit of sulphur constituent concentration generates purified gas.Below will further specify this CO
2Absorption tower 70.
As shown in Figure 2, in a kind of exemplary embodiment of the present invention, this CO
2Absorption tower 70 comprises: flash tank, packed tower and rise gas cap 75.Flash tank comprises tank body 71, and tank body 71 is provided with the first outlet 71a that is positioned at the top, the second outlet 71b that is positioned at the bottom, and is positioned at the inlet of first on sidewall 71c.Packed tower; Comprise tower body 73 and the fillers heap that is positioned at tower body 73 inside; Tower body 73 is provided with the first gas access 73a that is positioned at the bottom of the tower; Be positioned at the first gas vent 73b of cat head, the first liquid outlet 73c between the first gas access 73a and filler heap, and the first liquid inlet 73d between the first gas vent 73b and filler heap.Rise gas cap 75, link to each other with the first gas access 73a with the first outlet 71a respectively, gas phase is communicated with flash tank 71 and packed tower 73.
This CO
2Absorption tower 70 is simple in structure; Preparation easily; And floor space is little, can be applied directly to existing regenerated methanol and wash in the system, on the basis that does not increase extra charge; Just can prepare can be efficiently, flexibly, safety, energy-conservation handle different pressures, temperature, water content, and the novel regenerated methanol of the carbonyl gas do not limit of sulphur constituent concentration is washed system.
This methyl alcohol washes that the methyl alcohol system of washing compares in system and the prior art, adopts CO
2Absorption tower 70 has replaced old flash tank 7 ', through this CO
2The packed tower that is provided with in the absorption tower 70 further discharges CO to the flash distillation resulting gas
2Gas, and then the energy consumption and methanol wash tower 4 gas phases of employed recycle gas compressor 3 are loaded in the backflow of minimizing circulating air, more help the long-term use that methyl alcohol is washed equipment.Simultaneously, increasing this CO
2Behind the absorption tower 70, wash the flashing pressure that can increase flash tank 70 in the production engineering, more help increasing the rate of recovery of effective purified gas at methyl alcohol.
Filler heap adopts the material of the gas joint that helps generating in poor methanol and the flash tank to get final product in above-mentioned packed tower, and those skilled in the art are under instruction of the present invention, and the material that can reasonably select filler to pile repeats no more at this.
Preferably, above-mentioned CO
2Also comprise liquid distribution trough 77 in the packed tower on absorption tower, liquid distribution trough 77 is arranged on the inside of tower body 73, between the first gas vent 73b and filler heap, and is connected with the first liquid inlet 73d.Being provided with of liquid distribution trough is beneficial to impels poor methanol in packed tower, to flow equably, and then the gas that helps generating in poor methanol and the flash tank fully contacts, and fully absorbs the CO in the gas that generates in the flash tank
2
Preferably, above-mentioned CO
2Also be provided with demister in the packed tower on absorption tower, this demister is provided with the inside of tower body 73, is positioned at the side of liquid distribution trough near the first gas vent 73b.This demister, is avoided piling up the purified gas that is caused because of foam and is effluxed painstakingly to CO so that the purified gas that is produced is got rid of from the cat head of packed tower in order to remove the foam that possibly pile up on the liquid distribution trough
2The gas phase load that the absorption tower produces.
In traditional washing device for methanol, decarbonization section 4a that methanol wash tower 4 comprises epimere and the hypomere desulfurization section 4b that is positioned at tower, this methanol wash tower 4 also can be by two independently scrubbing tower link to each other and form, become decarburization scrubbing tower 4a and desulfurization washing tower 4b at this moment.Decarbonization section 4a carries out carbonization treatment to unstripped gas, and desulfurization section 4b carries out desulfurization to unstripped gas to be handled.。
In order to reduce to investment of devices, in a kind of concrete embodiment of the present invention, above-mentioned CO
2Also comprise the second gas access 73e in the packed tower on absorption tower, the second gas access 73e is arranged between the first gas access 73a and the filler heap.At this moment, this CO
2The absorption tower links to each other with decarbonization section 4a or desulfurization section 4b, not with CO
2Decarbonization section 4a that the absorption tower links to each other or desulfurization section 4b connect one second flash tank 8, the gas vent of this second flash tank 8 and CO
2The second gas access 73e in the packed tower on absorption tower links to each other.Such design can reduce equipment investment, can also realize stable application simultaneously.
Preferably, above-mentioned CO
2The absorption tower, the second gas access 73e and the first liquid outlet 73c are separately positioned on the sidewall of packed tower 73 in the packed tower, and are positioned at vertical plane both sides, first gas access 73a place.This structure helps being contacted with poor methanol better by the second inlet gas that in flash tank, generates that 73e flowed into, so that remove the CO in the gas that generates in the flash tank better
2
As shown in Figure 3; In a kind of comparatively concrete embodiment; Methanol wash tower 4 comprises decarbonization section 4a that is positioned at scrubbing tower 4 epimeres and the desulfurization section 4b that is positioned at scrubbing tower 4 hypomeres in the gas absorbing device of this low-temperature rectisol equipment, and the liquid phase outlet of decarbonization section 4a links to each other with the gas phase inlet of desulfurization section 4b; At this moment, CO
2In the absorption tower 70 on the flash tank 71 first inlet 71c links to each other with the outlet of desulfurization section 4b, and CO
270 are provided with the second gas access 73e that is located between the first gas access 73a and the filler heap; Second flash tank 8 is arranged between decarbonization section 4a and the gas desorption apparatus, the gas vent of second flash tank 8 be arranged on CO
2The packed tower second gas access 73e links to each other in the absorption tower 70, and the liquid outlet of second flash tank 8 links to each other with the gas desorption device.In this embodiment, this methyl alcohol is washed in the absorption plant of system and is comprised two streams, and wherein one is that the second poor methanol solution 51 flows into from the upper end that methyl alcohol is washed system, through flowing into CO behind decarburization scrubbing tower 4a, the desulfurization washing tower 4b
2Absorption tower 70 is at CO
2Flash distillation and CO are carried out in absorption tower 70
2The step that refluxes, second stream are that the second poor methanol solution 51 flows into from the upper end of washing device for methanol 4, and through flowing into second flash tank 8 behind the decarbonization section 4a, the gas second gas access 73e that flash distillation generates flows into CO
2Packed tower carries out CO in the absorption tower 70
2The step that refluxes.This mode can reduce CO
2The usage quantity on absorption tower 70 reduces equipment investment, has guaranteed CO simultaneously
2The stable of step that refluxes carries out.
Preferably, above-mentioned methyl alcohol is washed CO in the system
2Be provided with first supercharging device 101 between the first liquid inlet 73d on absorption tower 70 and the inlet of desulfurization section 4b.This first supercharging device 101 is in order to CO
2The backflow rich methanol 106 that the first liquid inlet 73d on absorption tower 70 reserves is pressurized to 2.5～8.5MPa, to overcome the resistance that potential difference from downstream, pipeline etc. bring.
Preferably, above-mentioned methyl alcohol washes that the poor methanol delivery device is the hot regenerator 19 of methyl alcohol in the hot regenerating unit of methyl alcohol in the equipment, CO
2The first liquid inlet 73d of packed tower links to each other with the liquid outlet of the hot regenerator 19 of methyl alcohol in the absorption tower.
Preferably, above-mentioned methyl alcohol is washed CO in the equipment
2Be provided with second supercharging device 100 and at least one poor methanol cooler 14,12,5 between the first liquid inlet 73d of middle packed tower and the liquid outlet of the hot regenerator 19 of methyl alcohol.Second supercharging device 100 carries out supercharging in order to the poor methanol that will be flowed out by the liquid outlet of the hot regenerator 19 of methyl alcohol; Be pressurized to 1.2～2.0MPa; To overcome dirty pressure; Poor methanol cooler 14,12,5 is lowered the temperature in order to the poor methanol that will be flowed out by the liquid outlet of the hot regenerator 19 of methyl alcohol, is cooled to-45～-65 ℃ so that absorb the CO in the gas that the flash distillation processing obtains
2
As shown in Figure 3, below will provide a kind of concrete operation method of low temperature washing device for methanol of the present invention.
From the liquid poor methanol solution 68 of the hot regenerator of methyl alcohol 19 bottoms, tell a part of poor methanol solution, as the second poor methanol solution precursors 102; Its consumption is 0.5～4.3% of the total input amount of first, second, third poor methanol solution, through 100 superchargings of first booster pump, forms the second poor methanol solution intermediate 103; After the supercharging; The pressure of the second poor methanol solution intermediate 103 can be increased to 1.2～1.6MPa by about 0.4MPa.To the poor methanol midbody solution 103 after the supercharging; Tell second portion in the liquid poor methanol solution 68 with the hot regenerator of methyl alcohol 19 bottoms; The first poor methanol precursor 81 together; Successively through three two-tube-pass around heat exchange of heat pipe, carry out temperature exchange with the rich methanol that is generated in the course of reaction, reduce to and be suitable for absorbing CO
2Temperature.After the cooling processing, the temperature of the second poor methanol solution 104 can be by dropping to-45～-65 ℃ more than 100 ℃.Through the supercharging methanol solution 104 later, from CO with cooling
2The top of absorption plant 70 sprays into, and in packed absorber, presses in the flash tank 70 and 8 CO in a large amount of circulation flash steam that after the throttling step-down, produced in the absorption
2Gas generates backflow rich methanol 106.After absorbing for the third time, get into the CO in the 3rd gas 37 in the recycle gas compressor 3
2Molar concentration be 0.10～0.60.And from CO
2Extraction in the absorption plant 70 has absorbed CO
2The backflow rich methanol solution 106 of gas is driven into the desulfurization section 4b on main absorption tower 4 through second booster pump 101, continues to absorb the acid gas components in the raw gas.
In the present invention, the part in the liquid poor methanol 68 of the hot regenerator of methyl alcohol 19 bottoms flow into CO as the second poor methanol precursor 102 after through 100 superchargings of second supercharging device
2In the absorption plant 70; This mode has just alleviated the power consumption that is connected the poor methanol solution circulation pump 18 between hot regenerator 19 of methyl alcohol and the methanol-water knockout tower 27 in the hot regenerating unit of methyl alcohol; Reduced loss, prolonged service life poor methanol solution circulation pump 18.
Secondly, in the present invention, the part in the liquid poor methanol 68 of the hot regenerator of methyl alcohol 19 bottoms with as the cooling of the first poor methanol precursor 81 through subcooler 14,12,5, can be reduced to identical temperature as the second poor methanol precursor 102.And low poor methanol solution 104 temperature, can reduce because operating pressure reduces, and the methanol solution that causes is to CO
2The degree of the reduction of solvability correspondingly, has also just reduced the flow of poor methanol solution 104, and then has also just further reduced the energy consumption of first and second grade booster pump 100,101.
Once more, cooler 14,12,5 can adopt heat exchanger, for example through with of the prior art; Be used for three of low-temp methanol washing process and become two-tube-pass around heat exchange of heat pipe by single-pass and form, this equipment investment around heat exchange of heat pipe only is directly proportional with its weight; And among the present invention around the thermic load of heat exchange of heat pipe, with existing low-temp methanol washing process relatively, do not increase; What change only is to have increased a very little tube side, and this variation, to almost not influence of weight of equipment; That is to say how many influences the equipment investment that the present invention can't the opposing connection heat exchange of heat pipe brings.
And, in the present invention, because second poor methanol 104 is at CO
2Absorb pressure in the absorption plant 70 and had the CO in the much lower flash distillation circulating air of low-temp methanol washing process now
2Gas.Make low-temp methanol washing method provided by the present invention under the prerequisite that effectively gas recovery rate significantly improves; The total amount of circulating air does not have great variation; And the power consumption of recycle gas compressor 3; Be closely-related, that is to say that the present invention does not bring great influence to the operating cost or the investment of recycle gas compressor 3 with the tolerance of circulating air.Simultaneously, the gas phase load to main absorption tower 4 also almost has no influence.
In addition, in the present invention, when operational load reduces, can be through pressing the operating pressure of flash distillation in regulating, perhaps the flow of the second poor methanol solution precursors 102 comes flexible CO
2The middle gas, liquid of absorption plant 7 of pressing is loaded, and then guarantees the efficient operation of this packed tower.Simultaneously, because, even the operating pressure of middle pressure flash distillation reduces, total its tolerance is also less relatively, and need be with the CO in the middle pressure flash distillation circulating air
2Remove fully, so CO
2The middle tower diameter and the tower height of absorption plant 70 of pressing is all less relatively, and its cost of equipment also will be very low accordingly.
This shows; At low-temp methanol washing method provided by the present invention; Can in reducing circulating air compressor 3 and the hot regenerating unit of methyl alcohol, be connected under the prerequisite of power consumption of the poor methanol solution circulation pump 18 between hot regenerator 19 of methyl alcohol and the methanol-water knockout tower 27,, significantly improve the available gas rate of recovery of low temperature washing device for methanol through the pressure of further reduction flash distillation; Wherein, the rate of recovery of the most difficult CO that reclaims is also more than 99.5%.
Below will combine specific embodiment, further specify beneficial effect of the present invention:
Embodiment 1
Preparation method:, low-temp methanol washing method of the present invention is further described below in conjunction with accompanying drawing 2 and 3:
The first poor methanol solution 30 and spray methyl alcohol 30 are converged with circulating air 29; Carry out absorbing the first time, form gas-liquid mixture, this gas-liquid mixture is cooled to about-12.0 ℃ through feed gas chiller 1; Form the first rich methanol solution 34; This first rich methanol solution 34 gets into gas-liquid separator 2, behind the separating and dehydrating, generates first gas and first liquid 36.First liquid 36 is deviate from water through methanol-water knockout tower 27, reclaims behind the generation methanol steam.First gas gets into methanol wash tower 4; Use the second poor methanol solution 51 under overhead streams; In the epimere decarbonization section of tower, accomplish carbonization treatment, generate the second rich methanol solution, and accomplish desulfurization with first's second rich methanol 43 at the hypomere desulfurization section of tower and handle; Generate the 3rd rich methanol solution 38; First gas generates after desulfurization and decarburization is handled and goes out the battery limit (BL) after purified gas 39 reclaims cold, and the second portion second rich methanol solution 42 carries out solution-air and is separated in second flash tank 8, generate A part second gas 31 and A part flash distillation rich methanol solution 45.The 3rd rich methanol 38 is at CO
2In the flash tank 71 of absorption plant 70 bottoms, carry out solution-air and be separated, B part second gas and B part flash distillation rich methanol solution 46.Wherein, A part second gas 31 converges formation second gas mutually with B part second gas, and second gas enters into CO through rising gas cap 75
2In the packed tower of absorption plant 70, after the second poor methanol solution 104 that is sprayed into from cat head absorbs sour gas, form the 3rd gas 37, the three gases 37 and will reduce greatly with respect to the gas gross of second gas.Afterwards, be that circulating air 29 uses through recycle gas compressor 3 compression superchargings again.A part flash distillation rich methanol solution 45 all gets into CO respectively with B part flash distillation rich methanol solution 46
2Product tower 9 and H
2The middle part of S concentration tower 10.
No sulphur rich methanol solution 45 (being A part flash distillation rich methanol solution) advances CO
2Be divided into 2 strand 48 of 1 strand 49 of no sulphur rich methanol solution A and no sulphur rich methanol solution A behind product tower 9 tops, no sulphur rich methanol solution A flows into CO for 1 strand 49
2The top of product tower 9, no sulphur rich methanol solution A flows into H for 2 strand 48
2The top of S concentration tower 10, same, sulfur-bearing rich methanol solution 46 (being B part flash distillation rich methanol solution) is divided into 2 strand 50 of 1 strand 47 of sulfur-bearing rich methanol solution B and sulfur-bearing rich methanol solution B, and sulfur-bearing rich methanol solution B flows into CO for 1 strand 47
2The middle part of product tower 9, sulfur-bearing rich methanol solution B flows into H for 2 strand 50
2The middle part of S concentration tower 10.Flow into H
22 strand 48 of no sulphur rich methanol solution B in the S concentration tower 10 and sulfur-bearing rich methanol solution A further expand for 2 strand 50; Desorb generates the 4th rich methanol solution 53 after going out gas; The 4th rich methanol solution 53 extracts through pump 15; Warp and the part of being used as first poor methanol by the liquid poor methanol solution 68 of the hot regenerator of methyl alcohol 19 bottoms, the first poor methanol intermediate 52 and 42 heat exchange of second portion second rich methanol flow into CO after the intensification
2The lower end of product tower 9 is at CO
2Product tower 9 is separated a large amount of CO of dissolving in the sucking-off solution
2Behind the gas, and through CO
2No sulphur rich methanol stream strand A1 thigh 49 after 9 desorbs of product tower and a sulfur-bearing rich methanol stream strand B1 thigh 47 converge and form the 5th rich methanol solution 57, the five rich methanol solution 57 and flow into H
2S concentration tower 10 hypomeres are at H
2Lower end feeding low-pressure nitrogen 59 gas of S concentration tower 10 are carried and are made CO
2Take off suction, reach H
2Generate the 6th rich methanol 58 after the purpose that the S quilt concentrates.At CO
2Separate the CO of sucking-off in the product tower 9
240 from CO
2The top of product tower 9 is discharged the back cooling, is reclaimed.At H
2Gas and the low-pressure nitrogen 59 of separating sucking-off in the S concentration tower 10 get into H through rising the gas plate
2S concentration tower epimere after no sulphur rich methanol solution A 2 desulfurization with cat head, forms tail gas 41 from H
2S concentration tower cat head flows out, and enters atmosphere behind the cold.
Above-mentioned the 6th rich methanol 58 is from H
2After flow out S concentration tower 10 bottoms; After pressurizeing, heating, flow in the hot regenerator 19 of methyl alcohol; The step of in Fig. 3, pressurizeing is accomplished through first feed pump 11 and second feed pump 17, and the step of heating is through carrying out the temperature displacement with poor methanol solution 68 in the first poor methanol cooler 12 and the second poor methanol cooler 14.After above-mentioned the 6th rich methanol 58 flow into the hot regenerator 19 of methyl alcohol, the methanol steam that produces through tower bottom reboiler, and from the methanol steam stripping of methanol-water knockout tower 27, to contained H in the 6th rich methanol 58
2S and CO
2Carry out complete desorb, generate reflux gas and poor methanol solution 68.
Above-mentioned reflux gas is through cooling, gas-liquid separation, cooling again, a part is sent to Sulfur Recovery Unit workshop section as sour gas 72 after re-heat after the gas-liquid separation again, and a part feeds H as circulating air
2The bottom of S concentration tower 10.Reflux gas forms first reflux gas 63 and first withdrawing fluid 69 in knockout drum 21 after condenser 20 coolings in Fig. 1; First withdrawing fluid 69 is pumped through pump 22 and is flow back in the hot regenerator 19 of methyl alcohol; First reflux gas 63 is after cool exchanger 23 and ammonia cooler 24 cool off once more; Flow into gas-liquid separator 25, separate forming second reflux gas 64 and second withdrawing fluid 154.Second withdrawing fluid 154 is back to H
2The bottom of S concentration tower 10, second reflux gas 71 is divided into two parts, and a part 65 is sent to Sulfur Recovery Unit workshop section, and a part 155 feeds H as circulating air
2The bottom of S concentration tower 10.
A poor methanol solution part that flows out from the hot regenerator of methyl alcohol 19 bottoms extracts through pump 18; Use as second poor methanol at the top that after the second poor methanol cooler 14, the first poor methanol cooler 12 and 5 coolings of the 3rd poor methanol cooler, is back to methanol wash tower 4; Another part flow in the methanol-water knockout tower 27 after pump 18 extracts; Carry out gas-liquid separation; The methanol steam that in methanol-water knockout tower 27, is produced is back in the hot regenerator 19 of methyl alcohol, the 6th rich methanol 58 in the hot regenerator 19 of methyl alcohol is carried out gas carry, and remaining moisture 77 is got rid of.Third part 102 is backflow CO after second supercharging device, 100 second poor methanol coolers 14, the first poor methanol cooler 12 and 5 coolings of the 3rd poor methanol cooler
2Use as the 3rd poor methanol solution 106 at the top of absorption plant 70, and the consumption of the 3rd poor methanol solution 106 is that 0.5～4.2%, second supercharging device 100 of first, second, third poor methanol solution total amount has been increased to 1.2MPa with poor methanol by 0.4MPa.
Comparative Examples
Adopt the existing low temperature washing device for methanol technological process shown in the accompanying drawing 1.
Utilize embodiment 1 and Comparative Examples to produce purified gas
Raw material: to produce 40 billion cubic meter coal preparing natural gas engineerings per year is example, and the temperature of unstripped gas 28 is 40 ℃, and pressure is 5.3MPa, and flow is 308500 * 10Nm
3/ hr.In embodiment, Comparative Examples all is the unstripped gas by the resulting coal system W of the above-mentioned coal water slurry gasification of 6.5MPa gas, and its gas phase is formed data (volume), and butt is as shown in table 1:
Table 1
| CO | H 2 | CO 2 | N 2 | CH 4 | H 2S | COS | AR | |
| Vol％ | 15.21 | 48.01 | 36.12 | 0.15 | 0.04 | 0.36 | 0.003 | 0.11 |
Test 1:
Through press under the operating pressure of flash distillation the tolerance of the circulating air of Comparative Examples and embodiment, and CO wherein to the change of flashing pressure and in difference
2Amount, as shown in table 2:
Table 2
Difference by Henry's law knowledge Henry'S coefficient will cause the difference of gas with various to the sensitivity of pressure.In low-temp methanol, the H of dissolving
2, CO to the sensitivity of pressure much larger than CO
2So, can reclaim the available gas composition H that is dissolved in the methyl alcohol rich solution through middle pressure flash distillation to rich solution
2And CO, and pressure is low more, and the rate of recovery is high more, but visible from last table, separates the CO of sucking-off
2Also begin to increase sharply, particularly after 1.2MPa, its escaped quantity begins rapid rising especially.But, in an embodiment of the present invention, can regulate the CO in the circulating air through the flow that changes the second poor methanol solution 106
2Amount.Yet, nonetheless, also can find out from last table, what the operating pressure of middle pressure flash distillation neither immoderate decline, when operating pressure is reduced to 0.8MPa, the CO in the embodiment circulating air
2Amount also is big unacceptable.
Test 2
In difference, press under the operating pressure of flash distillation; The power consumption of the recycle gas compressor 3 of Comparative Examples and embodiment etc. (has also comprised the rising because of the methanol solution internal circulating load; And the increase of poor methanol circulating pump 18 power consumptions that cause), and the energy consumption of water cooler supporting with it, as shown in table 3:
Can find out that by data in the table 3 in Comparative Examples, the power consumption of recycle gas compressor 3 and water cooler supporting with it almost completely depends on, the CO in the circulating air
2Molar flow rate, this is not only because CO wherein
2The relative current value big, and mainly be because H
2With CO centering press flashing pressure variation and insensitive due to.This shows, in existing low-temp methanol washing process, consider with two aspects of the effective gas recovery rate of raising that pressing the flashing pressure scope in the selection is relatively to be fit at 1.7～1.9MPa from energy-conservation.
But, in an embodiment, can regulate the CO in the circulating air through the flow that changes second cold methanol 106
2Amount; And then also just can reduce the power consumption of recycle gas compressor 3 and water cooler supporting with it, can find out from last table, even if comprised the power consumption that 18 of poor methanol circulating pumps have increased; The reduction of its total power consumption; For existing low-temp methanol washing process, also be very considerable, and whole process is controlled fully.
In difference, press under the operating pressure of flash distillation, effective gas recovery rate of Comparative Examples and embodiment, as shown in table 4:
Table 4
Visible by data in the table 4; For Comparative Examples, embodiment just can improve effective gas recovery rate of low temperature washing device for methanol greatly under the very little prerequisite of the total energy consumption increase of recycle gas compressor 3 and poor methanol circulating pump 18; And for embodiment; When the operating pressure of middle pressure flash distillation dropped to 0.975MPa, the rate of recovery of various available gas (comprising CO) can surpass 99.5%.Simultaneously, the electric energy that consumes therefrom also is about 1/3rd of a Comparative Examples.
Can find out by above data, can under the situation that does not increase energy consumption, improve effective gas recovery rate of low temperature washing device for methanol greatly through adopting low-temp methanol washing method provided by the present invention.With 4,000,000,000 sides natural gas/year project is example, because the raising of effective gas recovery rate of embodiment, the annual gas production that increases will be more than 0.6 hundred million sides; In 1.7 yuan of every side's natural gases; And the institute's electric energy that consume when pressing flash distillation in carrying out under 1.8MPa with respect to Comparative Examples of skimming (70 * 10KW, with annual 8000 hours, the electric 1.0 yuan of meters of every degree) more; The annual economic benefit of bringing therefrom will be more than 9,000 ten thousand yuan.
Above-mentioned effect shows: low-temp methanol washing method provided by the present invention, the rate of recovery that can guarantee various available gas (comprising CO) neatly greatly reduce the consumption of energy simultaneously more than 99.5% with respect to existing low-temp methanol washing process; And the equipment that increases therefrom all be conventional mini-plant, and technology maturation, investment are extremely low, can not surpass to have 0.4% of low temperature washing device for methanol gross investment now; Simultaneously, because the CO in the circulating air
2Major part is absorbed, so can not bring influence to the gas phase load on main absorption tower 4; And absorbed CO
2Half poor methanol solution 106, can also be in the desulfurization section on main absorption tower 4, continue to absorb the sour gas in the unstripped gas.
More than be merely the preferred embodiments of the present invention, be not limited to the present invention, for a person skilled in the art, the present invention can have various changes and variation.All within spirit of the present invention and principle, any modification of being done, be equal to replacement, improvement etc., all should be included within protection scope of the present invention.
Claims (10)
1. a low-temp methanol washing method comprises the step that absorption, desorb and methyl alcohol heat are regenerated, and it is characterized in that the step of said absorption further comprises:
Adopt the first poor methanol solution (30) that unstripped gas (28) is carried out absorbing the first time, form gas-liquid mixture, form the first rich methanol solution (34) through cooling; The said first rich methanol solution (34) is carried out gas-liquid separation handle, form first gas and first liquid (36);
Adopt the second poor methanol solution (51) that said first gas is carried out absorbing the second time; Said first gas forms purified gas (39) after absorbing for the second time; Reclaim the cooling back, and the said second poor methanol solution (51) forms secondary and absorbs rich methanol solution after absorbing for the second time;
Said secondary is absorbed rich methanol solution carry out flash distillation, form second gas and flash distillation rich methanol solution;
Adopt the 3rd poor methanol solution (104) that said second gas is absorbed for the third time, form the 3rd gas (37) and backflow rich methanol solution, said the 3rd gas (37) flows in the said gas-liquid mixture as circulating air; Said backflow rich methanol solution refluxes and with the said second poor methanol solution (51) said first gas is carried out absorbing the second time.
2. according to the said methanol washing method of claim 1, it is characterized in that the said employing second poor methanol solution (51) further comprises the step that said first gas carries out absorbing for the second time:
Adopt the second poor methanol solution (51) and the reverse convection current of said first gas, said first gas carried out desulfurization, carbonization treatment to form said purified gas, wherein:
The said second poor methanol solution (51) is flowing through desulfurization section (4b) formation second rich methanol solution after desulfurization is handled;
The first of the said second rich methanol solution (43) flows through decarbonization section (4a) and after carbonization treatment, forms the 3rd rich methanol solution (38),
The step that said secondary absorption rich methanol solution is carried out flash distillation further comprises:
Second portion (42) in the said second rich methanol solution carries out flash distillation, forms A part second gas (31) and A part flash distillation rich methanol solution;
Said the 3rd rich methanol (38) is carried out flash distillation, form B part second gas and B part flash distillation rich methanol solution;
Said A part flash distillation rich methanol solution and said B part flash distillation rich methanol solution are transported to stripping apparatus and the hot reclaim equiment of methyl alcohol carries out the processing of desorb and the regeneration of methyl alcohol heat, and converge said A part second gas 31 and form said second gas with B part second gas.
3. according to the said methanol washing method of claim 2, it is characterized in that, adopt the 3rd poor methanol solution (104) that the step that said second gas absorbs is for the third time further comprised:
Adopting temperature be that-45～-65 ℃, pressure are that the 3rd poor methanol (104) and said second gas of 1.2～2.0MPa absorbs, and forms said the 3rd gas and said backflow rich methanol solution.
4. methanol washing method according to claim 3 is characterized in that, the step that said backflow rich methanol solution is refluxed further comprises:
Said backflow rich methanol solution is carried out supercharging, be back to said desulfurization section 4b after being pressurized to 2.8～8.5MPa.
5. methanol washing method according to claim 4; It is characterized in that the said first poor methanol solution (30), the second poor methanol solution (51) and the 3rd poor methanol solution (104) all adopt the poor methanol solution (68) that generates in the step by the regeneration of said methyl alcohol heat through supercharging and after heating up.
6. methanol washing method according to claim 5; It is characterized in that; Said the 3rd poor methanol solution (104) is that the poor methanol that is generated in the step by the regeneration of said methyl alcohol heat is pressurized to 1.2～2.0MPa through first supercharging device (100); Simultaneously, be cooled to-45～-65 ℃ of formation through at least one poor methanol cooler (14,12,5).
7. methanol washing method according to claim 1 and 2 is characterized in that, the input amount of said the 3rd poor methanol solution (104) is 0.5～4.3% of the total input amount of said first, second, third poor methanol solution.
8. methanol washing method according to claim 1 and 2 is characterized in that, CO described in the said backflow rich methanol solution (106)
2Molar concentration be 0.1～0.60%.
9. methanol washing method according to claim 1 is characterized in that, said second rich methanol of second portion (42) and/or said the 3rd rich methanol (38) are carried out in the step of flash distillation, and flashing pressure is 1.2-1.7MPa.
10. a low-temperature rectisol equipment comprises the gas absorbing device, gas desorption device and the hot regenerating unit of methyl alcohol that are linked in sequence, and said gas absorbing device comprises:
Cooler (1) is used to cool off through the first poor methanol solution (30) that absorbs for the first time and the gas-liquid mixture of unstripped gas (28) and forms the first rich methanol solution (34);
First gas-liquid separator (2) is used for that the said first rich methanol solution (34) is carried out gas-liquid separation and handles, and forms first gas and first liquid (36);
Methanol wash tower (4) is used to adopt the second poor methanol solution (51) that said first gas is carried out absorbing the second time, forms purified gas and secondary and absorbs rich methanol solution;
It is characterized in that, also comprise CO
2Absorption tower (70), said CO
2Absorption tower (70) is arranged between said methanol wash tower (4) and the said gas desorption device, comprising:
Flash tank comprises tank body (71), and said tank body (71) is provided with first outlet (71a) that is positioned at the top, second outlet (71b) that is positioned at the bottom, and is positioned at the inlet of first on the sidewall (71c); Described first inlet (71c) links to each other with the outlet of said methanol wash tower (4), and described second outlet (71b) links to each other with said gas desorption device;
Packed tower; Comprise tower body (73) and be positioned at the inner filler heap of said tower body (73); Said tower body (73) is provided with first gas access (73a) that is positioned at the bottom of the tower; Be positioned at first gas vent (73b) of cat head, be positioned at first liquid outlet (73c) between said first gas access (73a) and the said filler heap, and be positioned at first liquid inlet (73d) between said first gas vent (73b) and the said filler heap; Described first liquid inlet (73d) links to each other with the cold methanol delivery device, and first liquid outlet (73c) links to each other with the inlet of said methanol wash tower (4);
Rise gas cap (75), link to each other with said first gas access (73a) with said first outlet (71a) respectively, gas phase is communicated with said flash tank (71) and said packed tower (73).
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| CN103289754A (en) * | 2013-06-24 | 2013-09-11 | 神华集团有限责任公司 | Recovery method and apparatus of flash steam |
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| CN104140852A (en) * | 2013-11-22 | 2014-11-12 | 上海国际化建工程咨询公司 | Device and method for treating low temperature methanol washing ammonium crystallization and purifying barren solution methanol |
| CN112625761A (en) * | 2020-12-01 | 2021-04-09 | 中国五环工程有限公司 | Process for removing low-partial pressure acid gas in low-pressure feed gas by using low-temperature methanol |
| CN114788983A (en) * | 2021-01-26 | 2022-07-26 | 大连佳纯气体净化技术开发有限公司 | Low-temperature methanol cleaning method and device |
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