CN110655940A - System and method for preparing CNG (compressed natural gas) from medium-low temperature dry distillation raw gas through sulfur-resistant uniform temperature methanation - Google Patents
System and method for preparing CNG (compressed natural gas) from medium-low temperature dry distillation raw gas through sulfur-resistant uniform temperature methanation Download PDFInfo
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- 239000007789 gas Substances 0.000 title claims abstract description 93
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 title claims abstract description 56
- 238000000197 pyrolysis Methods 0.000 title claims abstract description 44
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 title claims abstract description 42
- 229910052717 sulfur Inorganic materials 0.000 title claims abstract description 39
- 239000011593 sulfur Substances 0.000 title claims abstract description 39
- 239000003345 natural gas Substances 0.000 title claims abstract description 23
- 238000000034 method Methods 0.000 title claims abstract description 15
- 238000006477 desulfuration reaction Methods 0.000 claims abstract description 42
- 230000023556 desulfurization Effects 0.000 claims abstract description 41
- 238000001179 sorption measurement Methods 0.000 claims abstract description 41
- 238000011084 recovery Methods 0.000 claims abstract description 31
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims abstract description 30
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims abstract description 22
- 229910002092 carbon dioxide Inorganic materials 0.000 claims abstract description 21
- 239000000428 dust Substances 0.000 claims abstract description 19
- 239000003915 liquefied petroleum gas Substances 0.000 claims abstract description 19
- 238000006481 deamination reaction Methods 0.000 claims abstract description 15
- 238000006297 dehydration reaction Methods 0.000 claims abstract description 15
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 15
- 230000009615 deamination Effects 0.000 claims abstract description 14
- 230000018044 dehydration Effects 0.000 claims abstract description 14
- 239000001569 carbon dioxide Substances 0.000 claims abstract description 11
- 238000007906 compression Methods 0.000 claims description 57
- 230000006835 compression Effects 0.000 claims description 56
- 238000006243 chemical reaction Methods 0.000 claims description 32
- 238000005262 decarbonization Methods 0.000 claims description 30
- 239000000571 coke Substances 0.000 claims description 18
- 229910000037 hydrogen sulfide Inorganic materials 0.000 claims description 14
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical compound S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 claims description 13
- 238000005261 decarburization Methods 0.000 claims description 13
- 239000003054 catalyst Substances 0.000 claims description 12
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 11
- 238000009835 boiling Methods 0.000 claims description 9
- WHDPTDWLEKQKKX-UHFFFAOYSA-N cobalt molybdenum Chemical compound [Co].[Co].[Mo] WHDPTDWLEKQKKX-UHFFFAOYSA-N 0.000 claims description 5
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 4
- 238000004519 manufacturing process Methods 0.000 claims description 4
- 229920006395 saturated elastomer Polymers 0.000 claims description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 3
- 239000001301 oxygen Substances 0.000 claims description 3
- 229910052760 oxygen Inorganic materials 0.000 claims description 3
- 239000000126 substance Substances 0.000 claims description 2
- 239000011269 tar Substances 0.000 abstract description 24
- 239000003245 coal Substances 0.000 abstract description 16
- 238000005516 engineering process Methods 0.000 abstract description 11
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 abstract description 10
- 239000006227 byproduct Substances 0.000 abstract description 9
- 229910052799 carbon Inorganic materials 0.000 abstract description 6
- 239000001273 butane Substances 0.000 abstract description 5
- IJDNQMDRQITEOD-UHFFFAOYSA-N n-butane Chemical compound CCCC IJDNQMDRQITEOD-UHFFFAOYSA-N 0.000 abstract description 5
- OFBQJSOFQDEBGM-UHFFFAOYSA-N n-pentane Natural products CCCCC OFBQJSOFQDEBGM-UHFFFAOYSA-N 0.000 abstract description 5
- 239000001294 propane Substances 0.000 abstract description 5
- 230000008901 benefit Effects 0.000 abstract description 4
- 238000000926 separation method Methods 0.000 abstract description 4
- 229930195733 hydrocarbon Natural products 0.000 abstract description 3
- 150000002430 hydrocarbons Chemical class 0.000 abstract description 3
- 239000000047 product Substances 0.000 abstract description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 abstract description 2
- 239000000567 combustion gas Substances 0.000 abstract description 2
- 238000000746 purification Methods 0.000 abstract description 2
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 description 6
- PVXVWWANJIWJOO-UHFFFAOYSA-N 1-(1,3-benzodioxol-5-yl)-N-ethylpropan-2-amine Chemical compound CCNC(C)CC1=CC=C2OCOC2=C1 PVXVWWANJIWJOO-UHFFFAOYSA-N 0.000 description 5
- QMMZSJPSPRTHGB-UHFFFAOYSA-N MDEA Natural products CC(C)CCCCC=CCC=CC(O)=O QMMZSJPSPRTHGB-UHFFFAOYSA-N 0.000 description 5
- 238000010438 heat treatment Methods 0.000 description 5
- 230000008569 process Effects 0.000 description 5
- 238000010521 absorption reaction Methods 0.000 description 4
- 230000003009 desulfurizing effect Effects 0.000 description 4
- OTMSDBZUPAUEDD-UHFFFAOYSA-N Ethane Chemical compound CC OTMSDBZUPAUEDD-UHFFFAOYSA-N 0.000 description 3
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 3
- 239000005977 Ethylene Substances 0.000 description 3
- 239000005864 Sulphur Substances 0.000 description 3
- 238000003763 carbonization Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- QQONPFPTGQHPMA-UHFFFAOYSA-N propylene Natural products CC=C QQONPFPTGQHPMA-UHFFFAOYSA-N 0.000 description 3
- 125000004805 propylene group Chemical group [H]C([H])([H])C([H])([*:1])C([H])([H])[*:2] 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 125000000383 tetramethylene group Chemical group [H]C([H])([*:1])C([H])([H])C([H])([H])C([H])([H])[*:2] 0.000 description 3
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 2
- MWPLVEDNUUSJAV-UHFFFAOYSA-N anthracene Chemical compound C1=CC=CC2=CC3=CC=CC=C3C=C21 MWPLVEDNUUSJAV-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- ZBCBWPMODOFKDW-UHFFFAOYSA-N diethanolamine Chemical compound OCCNCCO ZBCBWPMODOFKDW-UHFFFAOYSA-N 0.000 description 2
- 238000005265 energy consumption Methods 0.000 description 2
- 239000003546 flue gas Substances 0.000 description 2
- 230000008676 import Effects 0.000 description 2
- 229910000069 nitrogen hydride Inorganic materials 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 239000002253 acid Substances 0.000 description 1
- 150000001336 alkenes Chemical class 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 238000009903 catalytic hydrogenation reaction Methods 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 239000003034 coal gas Substances 0.000 description 1
- 239000011280 coal tar Substances 0.000 description 1
- 238000003795 desorption Methods 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000002737 fuel gas Substances 0.000 description 1
- XLYOFNOQVPJJNP-ZSJDYOACSA-N heavy water Substances [2H]O[2H] XLYOFNOQVPJJNP-ZSJDYOACSA-N 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 description 1
- JRZJOMJEPLMPRA-UHFFFAOYSA-N olefin Natural products CCCCCCCC=C JRZJOMJEPLMPRA-UHFFFAOYSA-N 0.000 description 1
- 125000001741 organic sulfur group Chemical group 0.000 description 1
- 239000012188 paraffin wax Substances 0.000 description 1
- 239000003209 petroleum derivative Substances 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10B—DESTRUCTIVE DISTILLATION OF CARBONACEOUS MATERIALS FOR PRODUCTION OF GAS, COKE, TAR, OR SIMILAR MATERIALS
- C10B53/00—Destructive distillation, specially adapted for particular solid raw materials or solid raw materials in special form
- C10B53/04—Destructive distillation, specially adapted for particular solid raw materials or solid raw materials in special form of powdered coal
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10B—DESTRUCTIVE DISTILLATION OF CARBONACEOUS MATERIALS FOR PRODUCTION OF GAS, COKE, TAR, OR SIMILAR MATERIALS
- C10B57/00—Other carbonising or coking processes; Features of destructive distillation processes in general
- C10B57/14—Features of low-temperature carbonising processes
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
- C10J3/00—Production of combustible gases containing carbon monoxide from solid carbonaceous fuels
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
- C10J3/00—Production of combustible gases containing carbon monoxide from solid carbonaceous fuels
- C10J3/72—Other features
- C10J3/82—Gas withdrawal means
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
- C10J3/00—Production of combustible gases containing carbon monoxide from solid carbonaceous fuels
- C10J3/72—Other features
- C10J3/82—Gas withdrawal means
- C10J3/84—Gas withdrawal means with means for removing dust or tar from the gas
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10K—PURIFYING OR MODIFYING THE CHEMICAL COMPOSITION OF COMBUSTIBLE GASES CONTAINING CARBON MONOXIDE
- C10K3/00—Modifying the chemical composition of combustible gases containing carbon monoxide to produce an improved fuel, e.g. one of different calorific value, which may be free from carbon monoxide
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
- C10L3/00—Gaseous fuels; Natural gas; Synthetic natural gas obtained by processes not covered by subclass C10G, C10K; Liquefied petroleum gas
- C10L3/06—Natural gas; Synthetic natural gas obtained by processes not covered by C10G, C10K3/02 or C10K3/04
- C10L3/08—Production of synthetic natural gas
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/10—Process efficiency
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- Organic Chemistry (AREA)
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- General Chemical & Material Sciences (AREA)
- Materials Engineering (AREA)
- Industrial Gases (AREA)
Abstract
The invention discloses a system and a method for preparing CNG (compressed natural gas) from medium-low temperature dry distillation raw gas through sulfur-resistant uniform temperature methanation, and belongs to the technical field of clean and efficient utilization of coal. Performing dust removal, deamination and purification on the dry distillation raw gas, and then recovering tar to obtain a high-value byproduct; then the high-grade hydrocarbons such as propane and butane are directly prepared into LPG by pressurization, liquefaction and separation. Desulfurization and dehydration deviceH desorbed from carbon device2The S gas has high purity, sulfur can be recovered by adopting a Claus sulfur recovery process, and combustible gas generated by nitrogen separated by a pressure swing adsorption system is used as combustion gas, so that the cost is saved. Gas component CH after separation of nitrogen by PSA4The content is high and is more than 95 percent, and the requirement of a first-grade natural gas product is met. The system is simple and convenient to operate, realizes clean and efficient utilization of low-rank coal by adopting a low-temperature destructive distillation poly-generation technology of coal, produces high-calorific-value compressed natural gas and byproducts such as tar, LPG, sulfur, carbon dioxide and the like, saves energy and has high economic benefit.
Description
Technical Field
The invention belongs to the technical field of clean and efficient utilization of coal, and particularly relates to a system and a method for preparing CNG (compressed natural gas) from medium-low temperature dry distillation raw gas through sulfur-resistant uniform temperature methanation.
Background
Natural gas, as a high-efficiency, clean and safe fossil energy, has increased year by year in global energy consumption; along with the enhancement of environmental awareness and the improvement of life quality of people, the demand of natural gas is increased year by year, coal resources with relatively rich reserves are utilized to deeply develop a low-temperature dry distillation natural gas co-production technology of low-quality coal, and raw gas with lower heat value is utilized to be converted into environment-friendly natural gas, so that the comprehensive utilization of the coal resources is realized, the phenomenon of relative shortage of oil and gas resources in China is relieved, and the clean and efficient utilization technical route of coal is met.
Three products are obtained in the semi-coke production process by low-temperature carbonization of low-quality coal, namely semi-coke, coal tar and raw coke gas (also called semi-coke tail gas or low-temperature carbonization gas), the components of the raw coke gas produced by a semi-coke production device which is generally heated by flue gas are shown in table 1, the raw coke gas has low methane content, low gas heat value and a large amount of nitrogen, the energy consumption in the compression and liquefaction processes is high, the process cost for directly purifying methane from the gas is high, the raw coke gas is generally combusted by a boiler to produce steam and generate electricity at present, and the economic benefit is low.The coal can generate a large amount of H in the low-temperature dry distillation process2CO and CO2But the hydrogen-carbon ratio (H/C) is about 1.8-2.2, which is not beneficial to methanation reaction, and also contains C2-C4 paraffin and olefin as main petroleum gas components, H2S、NH3And tar, dust, etc.
Table 1: crude gas component of traditional vertical furnace
With the development of the low-temperature dry distillation technology of pulverized coal in recent years, technologies such as an external heating type vertical furnace, a solid heat carrier low-temperature rapid pyrolysis technology, a pulverized coal rotary kiln pyrolysis technology and the like appear, the technology is different from the prior mode that flue gas is directly heated by adopting indirect heating, the produced raw coke oven gas has more effective combustible components, the general components of the raw coke oven gas are shown in a table 2, the content of nitrogen is obviously reduced, but the problems of low hydrogen-carbon ratio and high carbon dioxide content still exist.
Table 2: indirectly heated raw gas component for pyrolysis technology
Because of the characteristics of the raw coke oven gas, unlike the coke oven gas which is easy to prepare natural gas, the development of a technology for preparing natural gas by methanation, which is suitable for the raw coke oven gas, is urgently needed, and the technology can be used for preparing natural gas at a low H/C ratio and high CO2Under the condition of partial pressure, high CO conversion rate and high CH are realized4And (4) selectivity.
Disclosure of Invention
In order to solve the existing problems, the invention aims to provide a system and a method for preparing CNG (compressed natural gas) by performing sulfur-tolerant uniform-temperature methanation on medium-low-temperature dry distillation raw gas, so that clean and efficient utilization of low-rank coal is realized, high-calorific-value compressed natural gas is produced, byproducts such as tar, LPG (liquefied petroleum gas), sulfur, carbon dioxide and the like are produced, energy is saved, and economic benefit is high.
The invention is realized by the following technical scheme:
the invention discloses a system for preparing CNG (compressed natural gas) from middle-low temperature dry distillation raw gas through sulfur-resistant uniform temperature methanation, which comprises a deamination dust removal device, wherein the inlet of the deamination dust removal device is connected with a middle-low temperature dry distillation raw gas inlet pipe, the outlet of the deamination dust removal device is connected with a primary compression device, the primary compression device is connected with a tar recovery device, the tar recovery device is connected with a secondary compression device, the secondary compression device is connected with a sulfur-resistant methanation device and a liquefied petroleum gas collection device, the sulfur-resistant methanation device is connected with a desulfurization and decarbonization device, the desulfurization and decarbonization device is, carbon dioxide collection device and hydrogen sulfide collection device, hydrogen sulfide collection device are connected with claus sulphur recovery unit, and desulfurization decarbonization device is connected with the dehydration adsorption tower, and the dehydration adsorption tower is connected with pressure swing adsorption equipment, and pressure swing adsorption equipment is connected with nitrogen gas collection device and tertiary compression device, and tertiary compression device is connected with the CNG outlet duct.
Preferably, the first-stage compression device is a screw compressor, the second-stage compression device is a piston compressor, and the third-stage compression device is a centrifugal compressor.
Preferably, the tar recovery device is a rectifying tower or a temperature swing adsorption device.
Preferably, an oxygen removing device is arranged between the tar recovery device and the secondary compression device.
Preferably, the sulfur-resistant methanation device is a tubular uniform temperature reactor, a cobalt-molybdenum catalyst is arranged in a tube pass of the tubular uniform temperature reactor, and boiling water is 60-100 bar in a shell pass; the two ends of the tube pass are respectively connected with the secondary compression device and the desulfurization and decarburization device.
Further preferably, the shell side is connected with a steam drum, and the shell side, the steam drum, the tar recovery device and the desulfurization and decarburization device form a closed circulation loop of boiling water/saturated steam.
Preferably, the desulfurization and decarbonization device comprises a desulfurization tower and a decarbonization tower which are filled with MDEA solution, the inlet of the decarbonization tower is connected with the sulfur-tolerant methanation device, the outlet of the decarbonization tower is connected with the inlet of the desulfurization tower and the dehydration adsorption tower, and the outlet of the desulfurization tower is connected with the hydrogen sulfide collection device.
Preferably, the pressure swing adsorption unit is a pressure swing adsorption column.
The invention discloses a method for preparing CNG by adopting the system for preparing CNG from medium-low temperature dry distillation raw gas through sulfur-resistant uniform temperature methanation, which comprises the following steps:
the medium-low temperature dry distillation raw gas enters a deamination dust removal device from a medium-low temperature dry distillation raw gas inlet pipe, enters a primary compression device after ammonia removal and dust removal, enters a tar recovery device after pressurization, enters a secondary compression device after tar removal, enters a liquefied petroleum gas collection device after pressurization, enters a sulfur-resistant methanation device after reaction, enters a desulfurization and decarbonization device after reaction, and H separated by the desulfurization and decarbonization device2S enters a hydrogen sulfide collecting device and then enters a Claus sulfur recovery device to react to generate sulfur, and CO separated by a desulfurization and decarbonization device2Entering a carbon dioxide collecting device; residual gas in the desulfurization and decarbonization device enters a pressure swing adsorption device after entering a dehydration adsorption tower to remove moisture, nitrogen separated by the pressure swing adsorption device enters a nitrogen collection device, residual gas in the pressure swing adsorption device enters a three-level compression device, and CNG obtained after pressurization passes through a CNG outlet pipe output system.
Preferably, the first-stage compression device pressurizes gas to 4-6bar, the second-stage compression device pressurizes gas to 26-30bar, and the third-stage compression device pressurizes gas to more than 265 bar.
Compared with the prior art, the invention has the following beneficial technical effects:
the invention discloses a system for preparing CNG (compressed natural gas) from medium-low temperature dry distillation raw gas through sulfur-resistant uniform temperature methanation, which is used for recovering tar after dust removal, deamination and purification of the dry distillation raw gas to obtain a high-value byproduct; the high-grade hydrocarbons such as propane, butane and the like in the dry distillation coal gas are directly prepared into LPG through pressurization, liquefaction and separation, and simultaneously, a large amount of high-grade hydrocarbons are effectively utilized, so that the carbon load of a methanation section is greatly reduced, the thermal stability of the methanation catalyst is improved, and the service life of the methanation catalyst is prolonged. H desorbed from desulfurization and decarbonization device2The S gas has high purity, sulfur can be recovered by adopting a Claus sulfur recovery process, and combustible gas generated by nitrogen separated by a pressure swing adsorption system is used as combustion gas, so that the cost is saved. Gas component CH after separation of nitrogen by PSA4The content is high and is more than 95 percent, which reaches the first-grade natural gas productAnd (4) requiring.
Furthermore, the first-stage compression device is a screw compressor, the second-stage compression device is a piston compressor, the third-stage compression device is a centrifugal compressor, the type of the compression device is selected according to actual needs, the setting is reasonable, and the cost is saved.
Furthermore, an oxygen removal device is arranged between the tar recovery device and the secondary compression device, so that the activity of the catalyst in the subsequent reactor can be protected.
Furthermore, the sulfur-tolerant cobalt-molybdenum catalyst is adopted, the dual-function catalytic action of transformation and methanation is achieved, the traditional wet desulphurization and dry desulphurization process sections are omitted, the tubular reactor is adopted to replace the traditional multi-section heat-insulating fixed bed reactor, the process flow is shortened, and the equipment investment is saved; the combination of the sulfur-tolerant methanation catalyst and the temperature-equalizing tubular reactor controls the reaction temperature to be 300-400 ℃, thereby realizing high CO conversion rate and high CH of the raw coke oven gas with low hydrogen-carbon ratio4Selectivity, solves the problems of low CO conversion rate and CO conversion at the high temperature of 650 ℃ in the traditional heat-insulating bed of 550-2High selectivity (high reaction rate at high temperature in water gas reaction).
Furthermore, the medium-pressure steam generated by the shell and tube reactor can provide heat for the tar recovery device and the desulfurization and decarburization device, so that the optimal utilization of heat is realized, and the energy is saved.
Further, desulfurization and decarburization are carried out in one unit, and H can be removed simultaneously through an MDEA absorption tower2S and CO2Acid gas, for CO2At concentrations less than 30%, MDEA (diethanolamine) absorption desorption is more economical than PSA.
The method for preparing the CNG by adopting the system for preparing the CNG by performing sulfur-resistant uniform temperature methanation on the medium-low temperature dry distillation raw gas disclosed by the invention is simple and convenient to operate, realizes clean and efficient utilization of low-rank coal by adopting a coal low-temperature dry distillation poly-generation technology, produces high-calorific-value compressed natural gas and byproducts such as tar, LPG, sulfur, carbon dioxide and the like, saves energy and has high economic benefit.
Drawings
FIG. 1 is a schematic overall view of a system for preparing CNG from medium and low temperature dry distillation raw gas through sulfur-tolerant temperature equalization methanation.
In the figure: 1-medium and low temperature carbonization raw gas inlet pipe, 2-deamination dust removal device, 3-primary compression device, 4-tar recovery device, 5-secondary compression device, 6-sulfur-tolerant methanation device, 7-desulfurization and decarburization device, 8-Claus sulfur recovery device, 9-dehydration adsorption tower, 10-pressure swing adsorption device, 11-tertiary compression device, 12-liquefied petroleum gas collection device, 13-hydrogen sulfide collection device, 14-carbon dioxide collection device, 15-nitrogen collection device and 16-CNG outlet pipe.
Detailed Description
The invention will now be described in further detail with reference to the following drawings and specific examples, which are intended to be illustrative and not limiting:
FIG. 1 is a system for preparing CNG by methanation of medium and low temperature dry distillation raw gas through sulfur resistance at uniform temperature, which comprises a deamination dust removal device 2, wherein the inlet of the deamination dust removal device 2 is connected with a medium and low temperature dry distillation raw gas inlet pipe 1, the outlet of the deamination dust removal device is connected with a primary compression device 3, the primary compression device 3 is connected with a tar recovery device 4, and the tar recovery device 4 can adopt a rectifying tower or a temperature swing adsorption device; the tar recovery device 4 is connected with a secondary compression device 5, and a deaerating device can be arranged between the tar recovery device 4 and the secondary compression device 5; the secondary compression device 5 is connected with a sulfur-resistant methanation device 6 and a liquefied petroleum gas collection device 12, the sulfur-resistant methanation device 6 is a tubular isothermal reactor, a cobalt-molybdenum catalyst is arranged in the tube pass of the tubular isothermal reactor, and boiling water is 60-100 bar in the shell pass; the two ends of the tube pass are respectively connected with a secondary compression device 5 and a desulfurization and decarburization device 7. The shell pass is connected with a steam drum, and the shell pass, the steam drum, the tar recovery device 4 and the desulfurization and decarburization device 7 form a closed circulation loop of boiling water/saturated steam.
Sulphur-resistant methanation device 6 is connected with desulfurization decarbonization device 7, and desulfurization decarbonization device 7 is including filling desulfurizing tower and the decarbonization tower of MDEA solution, and the import and the sulphur-resistant methanation device 6 of decarbonization tower are connected, and the export is connected with the import and the dehydration adsorption tower 9 of desulfurizing tower, and the export and the hydrogen sulfide collection device 13 of desulfurizing tower are connected.
The hydrogen sulfide collecting device 13 is connected with a Claus sulfur recovery device 8, the desulfurization and decarburization device 7 is connected with a dehydration adsorption tower 9, the dehydration adsorption tower 9 is connected with a pressure swing adsorption device 10, and the pressure swing adsorption device 10 can select a pressure swing adsorption tower; the pressure swing adsorption device 10 is connected with a nitrogen collecting device 15 and a three-stage compression device 11, and the three-stage compression device 11 is connected with a CNG outlet pipe 16.
Screw compressor can be chooseed for use to one-level compressor arrangement 3, and piston compressor can be chooseed for use to second grade compressor arrangement 5, and centrifugal compressor can be chooseed for use to tertiary compressor arrangement 11.
The system for preparing CNG from medium-low temperature dry distillation raw gas through sulfur-resistant uniform temperature methanation is in work:
the medium-low temperature dry distillation raw gas enters a deamination dust removal device 2 from a medium-low temperature dry distillation raw gas inlet pipe 1, ammonia gas is removed by washing, dust is removed by filtering, the gas enters a primary compression device 3, the gas is pressurized to 4-6bar and then enters a tar recovery device 4, components such as benzene, anthracene oil, tar and the like in the gas are recovered, and the content of benzene and tar in the recovered gas components is less than 5 ppm.
The residual gas enters a secondary compression device 5, the secondary compression device 5 pressurizes the gas to 26-30bar, liquefied petroleum gas components such as ethane, ethylene, propane, propylene, butane, butylene and the like are changed into liquid in the compression process, and the byproduct liquefied petroleum gas enters a liquefied petroleum gas collecting device 12.
And the residual gas enters a sulfur-tolerant methanation device 6, the sulfur-tolerant methanation device 6 adopts a tubular temperature-equalizing reactor, a catalyst is filled in a tube pass, boiling water of 60-100 bar flows away from a shell pass, and natural circulation of a steam drum and the reactor is formed through the density difference of the boiling water. The catalyst adopts cobalt-molybdenum catalyst, and is treated by H in raw material gas2S is reduced to generate active MoS at low airspeed2The water gas shift reaction and the methanation reaction can be simultaneously realized. As the hot spot temperature of the tubular temperature equalizing reactor is about 400 ℃, and the outlet temperature is 260-280 ℃, CO in the raw coke oven gas is basically and completely converted, and the selectivity of methane is over 85 percent. If the raw material gas is the raw gas of the traditional vertical furnace, the main components of the gas after the reaction of the sulfur-tolerant methanation device 6 are as follows: CH (CH)412-18 percent of the total carbon dioxide, and 0-0.3 percent of CO，H23-6% of CO212-18% of N240-50% of H2O content of 6-12%, CnHm(ethane, ethylene, propane, propylene, butane, butylene) content is 0.5-5%, H2S content of 500-3000 ppm and NH3The content is 300-1200 ppm. If the raw gas is low-temperature dry distillation raw gas generated by external heating type vertical furnace, solid heat carrier low-temperature fast pyrolysis and pulverized coal rotary kiln pyrolysis, the main components of the gas after the reaction of the sulfur-resistant methanation device 6 are as follows: CH (CH)445-55% of CO, 0-0.3% of H23-6% of CO28-12% of N20 to 20% of H2O content of 6-24%, CnHm(ethane, ethylene, propane, propylene, butane, butylene) content is 0.5-6%, H2The S content is 500-3000 ppm. In addition, organic sulfur and SO in raw gas2Also converted to H by catalytic hydrogenation2And S. Each 1000-square raw material gas is methanated by the sulfur-tolerant methanation device 6, so that 1.2-2.5 tons of saturated steam with the pressure of 60-100 bar can be byproduct, the byproduct can be used for solution heating analysis of the desulfurization and decarbonization device 7 and rectification or temperature swing adsorption of the tar recovery device 4, and the optimized utilization of heat is realized.
The main reactions that occur during methanation are as follows:
CO+3H2→CH4+H2O ΔH298K＝-206KJ/mol R1
CO2+4H2→CH4+2H2O ΔH298K＝-165KJ/mol R2
CO+H2O→H2+CO2 ΔH298K＝-41.2KJ/mol R3
according to the reaction formula, the reactions of R1 and R2 are strong exothermic reactions, the temperature rise of 72 ℃ is brought by every 1% of CO converted, and every 1% of CO converted2The temperature rise of 60 ℃ can be brought, the reaction activity is highest at about 300 ℃, the reaction rate equilibrium constant is smaller when the temperature is higher, and the reaction driving force is smaller. At present, the methanation process generally adopts a method of a multi-section adiabatic reactor and gas circulation to dilute the content of CO in feed gasThe first section of the adiabatic fixed bed methanation reactor usually reaches 620-650 ℃, the reactions of R1, R2 and R3 reach thermodynamic equilibrium at the temperature, and CO are2And CH4The content is controlled by thermodynamic equilibrium, the conversion rate of CO is lower, a plurality of adiabatic reactors are subsequently added to ensure the reaction depth, and finally the CO content is lower than 0.1%. And a tubular isothermal reactor is adopted, a tube pass is filled with a catalyst, a shell pass adopts boiling water for heat exchange to timely remove heat released by the reaction from the reactor, and medium-pressure steam is a byproduct. The tubular temperature equalizing reactor can control the reaction temperature to be 300-400 ℃, the R1 reaction equilibrium constant is large in the temperature range, and the high conversion rate of CO can be realized in a section of reactor after the reaction is continuously carried out.
After reaction, the reaction product enters a desulfurization and decarbonization device 7, and H is dissolved in MDEA (diethanolamine) solution under high pressure through physical dissolution and chemical absorption2S and CO2Dissolving or generating intermediate, decompressing and flashing in a decarbonizing tower to separate out high-purity CO2Then high-purity H is resolved by heating solution in a desulfurizing tower2And S. CO at the outlet of the desulfurization and decarbonization device 72Absorption rate of about 95%, H2The removal rate of S is more than 99 percent.
High-purity H separated by the desulfurization and decarbonization device 72S enters a hydrogen sulfide collecting device 13 and then enters a Claus sulfur recovery device 8 to react to generate sulfur, and CO separated by a desulfurization and decarbonization device 72Entering the carbon dioxide collection device 14; residual gas in the desulfurization and decarburization device 7 enters a dehydration adsorption tower 9 to remove moisture and then enters a pressure swing adsorption device 10, nitrogen separated by the pressure swing adsorption device 10 enters a nitrogen collection device 15, and separated nitrogen containing a small amount of methane and LPG component gas can be supplied to a Claus sulfur recovery device 8 as fuel gas to be combusted; methane and LPG component gas enter a three-stage compression device 11, the three-stage compression device 11 pressurizes the gas to 265bar to obtain a compressed natural gas product, CH in the natural gas4The content is more than 95 percent, and the balance is hydrogen and trace LPG components.
It should be noted that the above description is only one embodiment of the present invention, and all equivalent changes of the system described in the present invention are included in the protection scope of the present invention. Persons skilled in the art to which this invention pertains may substitute similar alternatives for the specific embodiments described, all without departing from the scope of the invention as defined by the claims.
Claims (10)
1. A system for preparing CNG (compressed natural gas) from medium-low temperature dry distillation raw gas through sulfur-resistant uniform-temperature methanation is characterized by comprising a deamination dust removal device (2), wherein an inlet of the deamination dust removal device (2) is connected with a medium-low temperature dry distillation raw gas inlet pipe (1), an outlet of the deamination dust removal device is connected with a primary compression device (3), the primary compression device (3) is connected with a tar recovery device (4), the tar recovery device (4) is connected with a secondary compression device (5), the secondary compression device (5) is connected with a sulfur-resistant methanation device (6) and a liquefied petroleum gas collection device (12), the sulfur-resistant methanation device (6) is connected with a desulfurization and decarbonization device (7), the desulfurization and decarbonization device (7) is connected with a dehydration adsorption tower (9), a carbon dioxide collection device (14) and a hydrogen sulfide collection device (13), and the hydrogen sulfide collection device (13), the desulfurization and decarbonization device (7) is connected with a dehydration adsorption tower (9), the dehydration adsorption tower (9) is connected with a pressure swing adsorption device (10), the pressure swing adsorption device (10) is connected with a nitrogen collection device (15) and a three-stage compression device (11), and the three-stage compression device (11) is connected with a CNG outlet pipe (16).
2. The system for preparing CNG from medium and low temperature dry distillation raw coke oven gas through sulfur-tolerant temperature equalization methanation according to claim 1, wherein the first-stage compression device (3) is a screw compressor, the second-stage compression device (5) is a piston compressor, and the third-stage compression device (11) is a centrifugal compressor.
3. The system for preparing CNG from medium and low temperature dry distillation raw gas through sulfur-tolerant temperature equalization methanation according to claim 1, wherein the tar recovery device (4) is a rectifying tower or a temperature swing adsorption device.
4. The system for preparing CNG from medium-low temperature dry distillation raw coke oven gas through sulfur-tolerant temperature equalization methanation according to claim 1, wherein an oxygen removal device is arranged between the tar recovery device (4) and the secondary compression device (5).
5. The system for preparing CNG from the medium-low temperature dry distillation raw gas through sulfur-resistant uniform-temperature methanation according to claim 1, wherein the sulfur-resistant methanation device (6) is a tubular uniform-temperature reactor, a cobalt-molybdenum catalyst is arranged in a tube pass of the tubular uniform-temperature reactor, and boiling water is 60-100 bar in a shell pass; two ends of the tube pass are respectively connected with a secondary compression device (5) and a desulfurization and decarburization device (7).
6. The system for preparing CNG from low-medium-temperature dry distillation raw gas through sulfur-tolerant uniform-temperature methanation according to claim 5, wherein a shell pass is connected with a steam drum, and the shell pass, the steam drum, the tar recovery device (4) and the desulfurization and decarbonization device (7) form a closed circulation loop of boiling water/saturated steam.
7. The system for preparing CNG (compressed natural gas) through sulfur-tolerant uniform-temperature methanation of medium-low-temperature dry distillation raw gas according to claim 1, wherein the desulfurization and decarbonization device (7) comprises a desulfurization tower and a decarbonization tower which are filled with MDEA (methyl-dimethyl-ammonium-ether-ethyl) solution, an inlet of the decarbonization tower is connected with the sulfur-tolerant methanation device (6), an outlet of the decarbonization tower is connected with an inlet of the desulfurization tower and the dehydration adsorption tower (9), and an outlet of the desulfurization tower is connected with the hydrogen sulfide collection device (13).
8. The system for preparing CNG from medium and low temperature dry distillation raw coke oven gas through sulfur-tolerant temperature equalization methanation according to claim 1, wherein the pressure swing adsorption device (10) is a pressure swing adsorption tower.
9. The method for preparing the CNG by adopting the system for preparing the CNG by methanation of the medium-low temperature dry distillation raw gas through sulfur resistance at the uniform temperature according to any one of claims 1 to 8 is characterized by comprising the following steps of:
the medium-low temperature dry distillation raw gas enters a deamination dust removal device (2) from a medium-low temperature dry distillation raw gas inlet pipe (1), enters a primary compression device (3) after ammonia gas removal and dust removal, enters a tar recovery device (4) after pressurization, enters a secondary compression device (5) after tar substances removal, and the liquefied petroleum gas enters liquefied petroleum gas after pressurizationThe residual gas enters a sulfur-tolerant methanation device (6), enters a desulfurization and decarburization device (7) after reaction, and H separated by the desulfurization and decarburization device (7) is collected by a collecting device (12)2S enters a hydrogen sulfide collecting device (13) and then enters a Claus sulfur recovery device (8) for reaction to generate sulfur, and CO separated by a desulfurization and decarbonization device (7)2Entering a carbon dioxide collection device (14); residual gas in the desulfurization and decarburization device (7) enters a dehydration adsorption tower (9) to remove moisture and then enters a pressure swing adsorption device (10), nitrogen separated by the pressure swing adsorption device (10) enters a nitrogen collection device (15), residual gas in the pressure swing adsorption device (10) enters a three-level compression device (11), and CNG obtained after pressurization passes through a CNG outlet pipe (16) output system.
10. A method for producing CNG according to claim 9, wherein the primary compression device (3) pressurizes the gas to 4 to 6bar, the secondary compression device (5) pressurizes the gas to 26 to 30bar, and the tertiary compression device (11) pressurizes the gas to 265bar or more.
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| CN104762116A (en) * | 2015-03-19 | 2015-07-08 | 青岛联信催化材料有限公司 | Production technology of natural gas or liquefied natural gas |
| CN211005244U (en) * | 2019-10-29 | 2020-07-14 | 中国华能集团有限公司 | System for preparing CNG (compressed natural gas) from medium-low temperature dry distillation raw gas through sulfur-resistant uniform-temperature methanation |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN104762116A (en) * | 2015-03-19 | 2015-07-08 | 青岛联信催化材料有限公司 | Production technology of natural gas or liquefied natural gas |
| CN211005244U (en) * | 2019-10-29 | 2020-07-14 | 中国华能集团有限公司 | System for preparing CNG (compressed natural gas) from medium-low temperature dry distillation raw gas through sulfur-resistant uniform-temperature methanation |
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