CN103175380B - Device for preparing LNG (liquefied natural gas) by low-concentration coal bed gas oxygen-containing cryogenic liquefaction - Google Patents
Device for preparing LNG (liquefied natural gas) by low-concentration coal bed gas oxygen-containing cryogenic liquefaction Download PDFInfo
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- CN103175380B CN103175380B CN201310117411.4A CN201310117411A CN103175380B CN 103175380 B CN103175380 B CN 103175380B CN 201310117411 A CN201310117411 A CN 201310117411A CN 103175380 B CN103175380 B CN 103175380B
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- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 title claims abstract description 33
- 239000001301 oxygen Substances 0.000 title claims abstract description 33
- 229910052760 oxygen Inorganic materials 0.000 title claims abstract description 33
- 239000007789 gas Substances 0.000 title claims description 81
- 239000003245 coal Substances 0.000 title claims description 19
- 239000003949 liquefied natural gas Substances 0.000 title abstract description 26
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims abstract description 114
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 57
- 239000012071 phase Substances 0.000 claims abstract description 29
- 239000004215 Carbon black (E152) Substances 0.000 claims abstract description 16
- 229930195733 hydrocarbon Natural products 0.000 claims abstract description 16
- 150000002430 hydrocarbons Chemical class 0.000 claims abstract description 16
- 239000007791 liquid phase Substances 0.000 claims abstract description 10
- 238000010992 reflux Methods 0.000 claims abstract description 9
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 51
- DOTMOQHOJINYBL-UHFFFAOYSA-N molecular nitrogen;molecular oxygen Chemical compound N#N.O=O DOTMOQHOJINYBL-UHFFFAOYSA-N 0.000 claims description 24
- 239000002826 coolant Substances 0.000 claims description 13
- QWTDNUCVQCZILF-UHFFFAOYSA-N isopentane Chemical compound CCC(C)C QWTDNUCVQCZILF-UHFFFAOYSA-N 0.000 claims description 12
- 238000005057 refrigeration Methods 0.000 claims description 12
- 238000004172 nitrogen cycle Methods 0.000 claims description 10
- 239000003345 natural gas Substances 0.000 claims description 7
- 238000000746 purification Methods 0.000 claims description 7
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 claims description 6
- 238000004140 cleaning Methods 0.000 claims description 6
- AFABGHUZZDYHJO-UHFFFAOYSA-N dimethyl butane Natural products CCCC(C)C AFABGHUZZDYHJO-UHFFFAOYSA-N 0.000 claims description 6
- 239000000203 mixture Substances 0.000 claims description 5
- 238000003860 storage Methods 0.000 claims description 4
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 claims description 3
- 239000001294 propane Substances 0.000 claims description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 3
- 238000000034 method Methods 0.000 abstract description 16
- 239000003507 refrigerant Substances 0.000 abstract description 10
- NLOAOXIUYAGBGO-UHFFFAOYSA-N C.[O] Chemical compound C.[O] NLOAOXIUYAGBGO-UHFFFAOYSA-N 0.000 abstract 1
- 239000000047 product Substances 0.000 description 10
- 238000001816 cooling Methods 0.000 description 6
- NNPPMTNAJDCUHE-UHFFFAOYSA-N isobutane Chemical compound CC(C)C NNPPMTNAJDCUHE-UHFFFAOYSA-N 0.000 description 6
- 238000009833 condensation Methods 0.000 description 5
- 230000005494 condensation Effects 0.000 description 5
- 238000001704 evaporation Methods 0.000 description 5
- 230000008020 evaporation Effects 0.000 description 5
- 239000000470 constituent Substances 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 239000001282 iso-butane Substances 0.000 description 3
- 235000013847 iso-butane Nutrition 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000000903 blocking effect Effects 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000006227 byproduct Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 238000007710 freezing Methods 0.000 description 1
- 230000008014 freezing Effects 0.000 description 1
- 239000003317 industrial substance Substances 0.000 description 1
- 238000005065 mining Methods 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 230000008929 regeneration Effects 0.000 description 1
- 238000011069 regeneration method Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
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Abstract
The invention discloses a device for preparing LNG (liquefied natural gas) by low-concentration coalbed methane oxygen-containing cryogenic liquefaction, which comprises a main process system and a refrigerating system; the main flow system comprises a primary heat exchanger, a secondary heat exchanger, a tertiary heat exchanger, a subcooler and a rectifying tower, wherein a tower top condenser and a reboiler are arranged in the rectifying tower, a nitrogen and oxygen outlet arranged at the tower top of the rectifying tower is connected with the tower top condenser, and a condensate outlet is arranged at the tower bottom of the rectifying tower; the refrigerating system comprises a mixed refrigerant circulating system and a nitrogen circulating system; the mixed refrigerant circulating system comprises a mixed refrigerant compressor, a mixed refrigerant cooler and a heavy hydrocarbon separator; the gas-phase mixed refrigerant of the heavy hydrocarbon separator is communicated with the reboiler through the primary heat exchanger and the secondary heat exchanger and then flows back; converging a liquid-phase mixed refrigerant and a gas-phase mixed refrigerant of the heavy hydrocarbon separator and then refluxing; the nitrogen circulating system comprises a nitrogen compressor and a nitrogen cooler, wherein the nitrogen cooler is communicated with the tower top condenser through the primary heat exchanger, the secondary heat exchanger, the tertiary heat exchanger and the subcooler in sequence and then flows back.
Description
Technical field
The invention belongs to and make gas or admixture of gas carry out the technical field liquefying, solidify or be separated by pressurization with cooling processing, concrete produces LNG device for a kind of low concentration coal-bed gas contains oxygen cryogenic liquefying.
Background technology
Coalbed methane containing oxygen be colliery in recovery process for preventing gas explosion and outstanding, ensure Safety of Coal Mine Production and the elementary byproduct that pumps out, its main component is methane, and as can be seen from its component content, coal bed gas is the energy and the industrial chemicals of outbalance.But because its composition is comparatively complicated, particularly in coal bed gas, contain aerobic, it is breakneck combustion-supporting pro-knock agent, constrain the comprehensive utilization of coalbed methane containing oxygen, in practice, in order to cost-saving, coal bed gas generally enters air in coal mining process, cause resource profligacy and to environment.
Along with the development of technology, purify at low concentration coal-bed gas at present and produce in the field of natural gas, occurred the liquefaction technology of multiple coalbed methane containing oxygen.Publication number is that CN101922850A and CN101929788A individually discloses a kind of method of coalbed methane containing oxygen to prepare liquefied natural gas and utilize the device of coalbed methane containing oxygen to prepare liquefied natural gas of utilizing, the method and device adopt azeotrope self-cascade refrigeration system, unstripped gas after purification is liquefied and is separated, obtain LNG product, although the method and device can utilize coalbed methane containing oxygen to produce natural gas, also there is following problem:
(1) unstripped gas (i.e. low concentration coal-bed gas) comes from underground coal mine extraction, and methane content fluctuation is comparatively large, can affect the stable operation of liquefaction process unavoidably, need to adjust device; And the purity of gas product and yield are controlled by evaporation capacity at the bottom of tower and overhead condensation amount respectively in the method and device, but at the bottom of tower heating and for tower top cool refrigerant fluid be with one, therefore overhead condensation amount (yield) can be affected when adjusting product purity, equally, evaporation capacity at the bottom of tower (purity) can be had influence on again when adjusting product yield;
(2) if refrigerant compressor operating mode is unstable, the heavy constituent in a large amount of azeotrope (as iso-butane, isopentane) can be caused to enter the low-temperature space (temperature is lower than-165 DEG C) of liquefying plant, cause this section of refrigerant temperature lower than its lower conversion temperature, after making throttling, temperature raises (namely not freezing), also can cause time serious solidifying, coolant channel is blocked;
(3), after in coal bed gas, methane is suggested, the direct re-heat under the operating pressure (0.3MPa) of rectifying column of nitrogen oxygen tail gas is emptying, does not fully reclaim its energy (pressure energy), wastes energy.
In view of this, the present invention is intended to explore a kind of low concentration coal-bed gas and produces LNG device containing oxygen cryogenic liquefying, this low concentration coal-bed gas produces containing oxygen cryogenic liquefying purity and the yield that LNG device independently can not only adjust gas product, and can prevent coolant channel from blocking, and improve using energy source.
Summary of the invention
A kind of low concentration coal-bed gas is the object of the present invention is to provide to produce LNG device containing oxygen cryogenic liquefying, this low concentration coal-bed gas produces containing oxygen cryogenic liquefying purity and the yield that LNG device independently can not only adjust gas product, and can prevent coolant channel from blocking.
For realizing above-mentioned technical purpose, the invention provides following technical scheme:
A kind of low concentration coal-bed gas produces LNG device containing oxygen cryogenic liquefying, comprises main flow system and refrigeration system;
Described main flow system comprises first-class heat exchanger, secondary heat exchanger, three grades of heat exchangers, subcooler and rectifying columns successively along the coal bed gas flow direction after purification, described rectifying column tower top arranges overhead condenser, the reboiler be positioned at the bottom of tower is set in rectifying tower, the nitrogen oxygen outlet that described rectifying column tower top is arranged is connected with the nitrogen oxygen outlet of described overhead condenser, and arranges condensate outlet at the bottom of the tower of described rectifying column;
Described refrigeration system comprises the azeotrope circulatory system and nitrogen cycle system;
The described azeotrope circulatory system comprises azeotrope compressor, azeotrope cooler and heavy hydrocarbon separator successively along azeotrope flow direction; The gas phase azeotrope outlet of described heavy hydrocarbon separator is communicated in the gas phase azeotrope entrance of described reboiler successively by first-class heat exchanger and secondary heat exchanger, the gas phase azeotrope outlet of described reboiler makes gas phase azeotrope reflux by three grades of heat exchangers, secondary heat exchanger and first-class heat exchanger successively and is communicated in the azeotrope entrance of described azeotrope compressor; The liquid phase azeotrope outlet of described heavy hydrocarbon separator is by converging with the gas phase azeotrope of backflow after first-class heat exchanger;
Described azeotrope is the mixture of nitrogen, methane, ethene, propane, isopentane;
Described nitrogen cycle system comprises nitrogen compressor and nitrogen cooler successively along the flow direction of nitrogen cooling agent, the nitrogen outlet of described nitrogen cooler is communicated in the nitrogen entrance of described overhead condenser successively by described first-class heat exchanger, secondary heat exchanger, three grades of heat exchangers and subcooler, the nitrogen outlet of described overhead condenser is made nitrogen cooling agent reflux by subcooler, three grades of heat exchangers, secondary heat exchanger and first-class heat exchanger and is communicated in the nitrogen entrance of described nitrogen compressor successively.
Further, described main flow system also comprises decompressor, the nitrogen oxygen outlet of described rectifying column is communicated in the nitrogen oxygen intake of described decompressor by described subcooler, the nitrogen oxygen outlet of described decompressor enters cleaning procedure by subcooler, three grades of heat exchangers, secondary heat exchanger and first-class heat exchanger after making the re-heat of nitrogen oxygen successively.
Further, the condensate outlet of described rectifying column is communicated in natural gas storage tank by described three grades of heat exchangers.
Further, described azeotrope cooler and nitrogen cooler are water cooler.
Further, the described azeotrope circulatory system also comprises choke valve V
1, the liquid phase azeotrope outlet of described heavy hydrocarbon separator is successively by first-class heat exchanger and choke valve V
1converge with the gas phase azeotrope of backflow.
Further, the gas phase azeotrope of described reboiler exports and be provided with choke valve V between described three grades of heat exchanger
2.
Further, choke valve V is provided with between the nitrogen entrance of described subcooler and overhead condenser
3.
Further, the coal bed gas of described subcooler exports and be provided with choke valve V between the coal bed gas entrance of rectifying column
f.
Beneficial effect of the present invention is:
Low concentration coal-bed gas of the present invention produces LNG device containing oxygen cryogenic liquefying, by refrigeration system being set to the azeotrope circulatory system and nitrogen cycle system, evaporation capacity at the bottom of the tower of rectifying column and the overhead condensation amount by nitrogen cycle Systematical control rectifying column is controlled by the azeotrope circulatory system, independently can adjust purity and the yield of gas product, and the cryogen of low-temperature space only has nitrogen component, there is not the heavy constituent such as iso-butane, isopentane, thus solution throttling is not freezed, or coolant channel blockage problem.
By decompressor, make it emptying at normal temperatures and pressures, thus fully reclaim the energy of the nitrogen oxygen backflowed, reach the object of energy-saving and emission-reduction.
Accompanying drawing explanation
In order to make object of the present invention, technical scheme and beneficial effect clearly, the invention provides following accompanying drawing and being described:
Fig. 1 is that low concentration coal-bed gas of the present invention produces the structural representation of LNG device embodiment containing oxygen cryogenic liquefying.
Detailed description of the invention
Below in conjunction with accompanying drawing, the preferred embodiments of the present invention are described in detail.
As shown in Figure 1, for low concentration coal-bed gas of the present invention contains the structural representation that oxygen cryogenic liquefying produces LNG device embodiment.The low concentration coal-bed gas of the present embodiment produces LNG device containing oxygen cryogenic liquefying, comprises main flow system and refrigeration system.
Main flow system comprises first-class heat exchanger 1, secondary heat exchanger 2, three grades of heat exchangers 3, subcooler 4 and rectifying columns 5 successively along the coal bed gas flow direction after purification, rectifying column 5 tower top arranges overhead condenser 6, the reboiler 7 be positioned at the bottom of tower is set in rectifying column 5 tower, the nitrogen oxygen outlet that rectifying column 5 tower top is arranged is connected with the nitrogen oxygen outlet of overhead condenser 6, and at the bottom of the tower of rectifying column 5, condensate outlet is set, flow out for liquified natural gas.Choke valve V is provided with between the coal bed gas outlet of the subcooler 4 of the present embodiment and the coal bed gas entrance of rectifying column 5
f, throttling cooling can be carried out to coal bed gas.
Refrigeration system comprises the azeotrope circulatory system and nitrogen cycle system.The azeotrope circulatory system comprises azeotrope compressor 8, azeotrope cooler 9 and heavy hydrocarbon separator 10 successively along azeotrope flow direction.The gas phase azeotrope outlet of heavy hydrocarbon separator 10 is communicated in the gas phase azeotrope entrance of reboiler 7 successively by first-class heat exchanger 1 and secondary heat exchanger 2, the gas phase azeotrope outlet of reboiler 7 is successively by three grades of heat exchangers 3, secondary heat exchanger 2 and first-class heat exchanger 1 make gas phase azeotrope reflux and are communicated in the azeotrope entrance of azeotrope compressor 8, the liquid phase azeotrope outlet of heavy hydrocarbon separator 10 is by converging with the gas phase azeotrope of backflow after first-class heat exchanger 1, reflux together with first-class heat exchanger 1 after liquid phase azeotrope converges with gas phase azeotrope and enter azeotrope compressor 8, azeotrope is recycled.The azeotrope circulatory system of the present embodiment also comprises choke valve V
1, the liquid phase azeotrope outlet of heavy hydrocarbon separator 10 is successively by first-class heat exchanger 1 and choke valve V
1converge, by arranging choke valve V with the gas phase azeotrope of backflow
1, expenditure and pressure can be carried out to liquid phase azeotrope.Choke valve V is provided with between the gas phase azeotrope outlet of the reboiler 7 of the present embodiment and three grades of heat exchangers 3
2, throttling cooling can be carried out to gas phase azeotrope.The azeotrope of the present embodiment is the mixture of nitrogen, methane, ethene, propane, isopentane, can meet the temperature control requirement in the links produced at liquefied natural gas, in azeotrope, the proportioning of each component sets according to the demand of actual refrigerating capacity.Certainly, azeotrope also can adopt the azeotrope of other components existing, is not repeated.
Nitrogen cycle system comprises nitrogen compressor 11 and nitrogen cooler 12 successively along the flow direction of nitrogen cooling agent, the nitrogen outlet of nitrogen cooler 12 is communicated in the nitrogen entrance of overhead condenser 6 successively by first-class heat exchanger 1, secondary heat exchanger 2, three grades of heat exchangers 3 and subcooler 4, the nitrogen outlet of overhead condenser 6 is made nitrogen cooling agent reflux by subcooler 4, three grades of heat exchangers 3, secondary heat exchanger 2 and first-class heat exchanger 1 and is communicated in the nitrogen entrance of nitrogen compressor 11 successively, nitrogen is recycled, and provides cold to overhead condenser 6.Choke valve V is provided with between the subcooler 4 of the present embodiment and the nitrogen entrance of overhead condenser 6
3, can lower the temperature to nitrogen cooling agent.
The low concentration coal-bed gas of the present embodiment produces LNG device containing oxygen cryogenic liquefying, by refrigeration system being set to the azeotrope circulatory system and nitrogen cycle system, evaporation capacity at the bottom of the tower of rectifying column 5 and the overhead condensation amount by nitrogen cycle Systematical control rectifying column 5 is controlled by the azeotrope circulatory system, independently can adjust purity and the yield of gas product, and the cryogen of low-temperature space only has nitrogen component, there is not the heavy constituent such as iso-butane, isopentane, thus solution throttling is not freezed, or coolant channel blockage problem.
Further, main flow system also comprises decompressor 13, the nitrogen oxygen outlet of rectifying column 5 is communicated in the nitrogen oxygen intake of decompressor 13 by subcooler 4, enter cleaning procedure after the nitrogen oxygen outlet of decompressor 13 makes the re-heat of nitrogen oxygen by subcooler 4, three grades of heat exchangers 3, secondary heat exchanger 2 and first-class heat exchanger 1 successively.By arranging decompressor 13, make it emptying at normal temperatures and pressures, thus fully reclaim the energy of the nitrogen oxygen backflowed, reach the object of energy-saving and emission-reduction.
Further, the condensate outlet of the rectifying column 5 of the present embodiment is communicated in natural gas storage tank by three grades of heat exchangers 3, makes gas product reach supercooled state, is convenient to store.
Further, azeotrope cooler 9 and the nitrogen cooler 12 of the present embodiment are water cooler, can meet the cooling requirement of azeotrope and nitrogen cooling agent, and are cooled to design temperature.
The process adopting the present embodiment low concentration coal-bed gas to produce LNG device production natural gas containing oxygen cryogenic liquefying is as follows:
1) cleaning procedure is compressed: low concentration is purified coalbed methane containing oxygen containing after the compressed purification of oxygen coal seam unstripped gas, and the temperature of the purification coalbed methane containing oxygen that the compressed cleaning procedure of the present embodiment obtains is 40 DEG C, absolute pressure is 0.42MPa.
2) liquefy separation circuit: comprise main flow technique and refrigeration process.
A. main flow technique:
A
1. coalbed methane containing oxygen will be purified successively by first-class heat exchanger 1, secondary heat exchanger 2, three grades of heat exchangers 3 and subcooler 4 heat exchange refrigeration, and through choke valve V
fthe mixture of condensate liquid and gas is formed after throttling;
A
2. purification coalbed methane containing oxygen enters rectifying column 5 from the middle part of rectifying column 5, condensate liquid flows to downwards at the bottom of tower, and a small amount of nitrogen oxygen tail gas carried that upwards volatilizees, flow out from condensate outlet after being heated by reboiler 7, and obtain that temperature is-143.5 DEG C, absolute pressure is 0.32 ~ 0.36MPa at condensate outlet, methane concentration be more than or equal to 99% liquefied natural gas, this liquefied natural gas is by the heat exchange of three grades of heat exchangers 3 and to reach temperature be-155 ~ 160 DEG C, pressure is storage with pressure after the supercooled state of 0.243MPa, obtains finished product natural gas;
A
3. the tower top of rectifying column 5 obtains nitrogen oxygen tail gas and separates out after a small amount of methane component of carrying through overhead condenser 6, after subcooler 4 re-heat, enter decompressor 13 again to expand, be expanded to the nitrogen oxygen tail gas after 0.15 ~ 0.18MPa successively by after subcooler 4, three grades of heat exchangers 3, secondary heat exchanger 2 and first-class heat exchanger 1 re-heat to normal temperature as the regeneration gas compressing cleaning procedure.
B. refrigeration process: comprise azeotrope technique and nitrogen cryogen technique.
B
1. azeotrope technique: the initial pressure of azeotrope is 0.26MPa, is compressed to 3.2-3.8Mpa through azeotrope compressor 8, enters heavy hydrocarbon separator 10 and be separated into gas-liquid two-phase after cooling; After wherein gas phase azeotrope is cooled to-120 DEG C by first-class heat exchanger 1 and secondary heat exchanger 2 successively, enter liquefied natural gas at the bottom of reboiler 7 heating tower be positioned at the bottom of rectifying column 5 tower, self is cooled to-148 DEG C, is that the gas phase azeotrope of-160 DEG C exports cold by three grades of heat exchangers 3, secondary heat exchanger 2 and first-class heat exchanger 1 successively and circulating reflux recycles to azeotrope compressor 8 after throttling by temperature; Liquid phase azeotrope is cooled to-50 DEG C by first-class heat exchanger 1, and converge with the gas phase azeotrope of backflow after throttling and together with first-class heat exchanger 1, be back to azeotrope compressor 8 recycle, what can meet liquefied natural gas produces requirement, and controls evaporation capacity at the bottom of the tower of rectifying column 5.
B
2. nitrogen cryogen technique: the initial pressure of nitrogen cryogen is 0.35MPa, 3.2 ~ 3.5MPa is compressed to through nitrogen compressor 11, successively by first-class heat exchanger 1 after cooling, secondary heat exchanger 2, three grades of heat exchangers 3 and subcooler 4 are cooled to-172 DEG C, after throttling, the temperature of nitrogen cryogen is-182 DEG C, absolute pressure is 0.4MPa, enter overhead condenser 6 and export cold, then the nitrogen cryogen of gaseous state is passed through subcooler 4 successively, three grades of heat exchangers 3, secondary heat exchanger 2, be back to nitrogen compressor 11 after first-class heat exchanger 1 cascade raising temperature to normal temperature to recycle, what can meet liquefied natural gas produces requirement, and control the overhead condensation amount of rectifying column 5.
What finally illustrate is, above preferred embodiment is only in order to illustrate technical scheme of the present invention and unrestricted, although by above preferred embodiment to invention has been detailed description, but those skilled in the art are to be understood that, various change can be made to it in the form and details, and not depart from claims of the present invention limited range.
Claims (7)
1. low concentration coal-bed gas produces a LNG device containing oxygen cryogenic liquefying, it is characterized in that: comprise main flow system and refrigeration system;
Described main flow system comprises first-class heat exchanger, secondary heat exchanger, three grades of heat exchangers, subcooler and rectifying columns successively along the coal bed gas flow direction after purification, described rectifying column tower top arranges overhead condenser, the reboiler be positioned at the bottom of tower is set in rectifying tower, the nitrogen oxygen outlet that described rectifying column tower top is arranged is connected with the nitrogen oxygen outlet of described overhead condenser, and arranges condensate outlet at the bottom of the tower of described rectifying column;
Described refrigeration system comprises the azeotrope circulatory system and nitrogen cycle system;
The described azeotrope circulatory system comprises azeotrope compressor, azeotrope cooler and heavy hydrocarbon separator successively along azeotrope flow direction; The gas phase azeotrope outlet of described heavy hydrocarbon separator is communicated in the gas phase azeotrope entrance of described reboiler successively by first-class heat exchanger and secondary heat exchanger, the gas phase azeotrope outlet of described reboiler makes gas phase azeotrope reflux by three grades of heat exchangers, secondary heat exchanger and first-class heat exchanger successively and is communicated in the azeotrope entrance of described azeotrope compressor; The liquid phase azeotrope outlet of described heavy hydrocarbon separator is by converging with the gas phase azeotrope of backflow after first-class heat exchanger;
Described azeotrope is the mixture of nitrogen, methane, ethene, propane, isopentane;
Described nitrogen cycle system comprises nitrogen compressor and nitrogen cooler successively along the flow direction of nitrogen cooling agent, the nitrogen outlet of described nitrogen cooler is communicated in the nitrogen entrance of described overhead condenser successively by described first-class heat exchanger, secondary heat exchanger, three grades of heat exchangers and subcooler, the nitrogen outlet of described overhead condenser is made nitrogen cooling agent reflux by subcooler, three grades of heat exchangers, secondary heat exchanger and first-class heat exchanger and is communicated in the nitrogen entrance of described nitrogen compressor successively;
Described main flow system also comprises decompressor, the nitrogen oxygen outlet of described rectifying column is communicated in the nitrogen oxygen intake of described decompressor by described subcooler, the nitrogen oxygen outlet of described decompressor enters cleaning procedure by subcooler, three grades of heat exchangers, secondary heat exchanger and first-class heat exchanger after making the re-heat of nitrogen oxygen successively.
2. low concentration coal-bed gas according to claim 1 produces LNG device containing oxygen cryogenic liquefying, it is characterized in that: the condensate outlet of described rectifying column is communicated in natural gas storage tank by described three grades of heat exchangers.
3. low concentration coal-bed gas according to claim 2 produces LNG device containing oxygen cryogenic liquefying, it is characterized in that: described azeotrope cooler and nitrogen cooler are water cooler.
4. low concentration coal-bed gas according to claim 1 produces LNG device containing oxygen cryogenic liquefying, it is characterized in that: the described azeotrope circulatory system also comprises choke valve V
1, the liquid phase azeotrope outlet of described heavy hydrocarbon separator is successively by first-class heat exchanger and choke valve V
1converge with the gas phase azeotrope of backflow.
5. low concentration coal-bed gas according to claim 4 produces LNG device containing oxygen cryogenic liquefying, it is characterized in that: be provided with choke valve V between the gas phase azeotrope outlet of described reboiler and described three grades of heat exchangers
2.
6. low concentration coal-bed gas according to claim 5 produces LNG device containing oxygen cryogenic liquefying, it is characterized in that: be provided with choke valve V between the nitrogen entrance of described subcooler and overhead condenser
3.
7. low concentration coal-bed gas according to claim 6 produces LNG device containing oxygen cryogenic liquefying, it is characterized in that: be provided with choke valve V between the coal bed gas outlet of described subcooler and the coal bed gas entrance of rectifying column
f.
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| CN201310117411.4A CN103175380B (en) | 2013-04-07 | 2013-04-07 | Device for preparing LNG (liquefied natural gas) by low-concentration coal bed gas oxygen-containing cryogenic liquefaction |
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| CN103983086B (en) * | 2014-05-19 | 2016-03-30 | 杭州杭氧股份有限公司 | A kind of method being applicable to synthesis gas piece-rate system in ammonia from coal device and cryogenic separation LNG |
| CN104315801A (en) * | 2014-10-15 | 2015-01-28 | 中国海洋石油总公司 | Mixed refrigerant-expansive refrigeration-circulated natural gas liquefying method |
| CN105486027A (en) * | 2015-11-17 | 2016-04-13 | 宁波鲍斯能源装备股份有限公司 | Recovery and utilization system for vent gas in low-concentration coal-bed gas liquidation process |
| CN105605883A (en) * | 2016-03-25 | 2016-05-25 | 北京中科瑞奥能源科技股份有限公司 | Oxygen-bearing coalbed methane liquefaction separation system and technique |
| CN108800754B (en) * | 2018-06-14 | 2023-09-08 | 北京恒泰洁能科技有限公司 | Device and method for preparing LNG (liquefied Natural gas) from tail gas of methanol-to-olefin methane |
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| CN102504900A (en) * | 2011-10-20 | 2012-06-20 | 辽宁哈深冷气体液化设备有限公司 | Equipment for preparing liquefied natural gas (LNG) from coke oven gas and method thereof |
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2013
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| WO1996002614A1 (en) * | 1994-07-20 | 1996-02-01 | Umsicht Institut Für Umwelt- Und Sicherheitstechnik E.V. | Method of enriching the methane content of a mine gas |
| CN101270952A (en) * | 2007-10-12 | 2008-09-24 | 北京国能时代能源科技发展有限公司 | Air backheating type mine gas separation and liquefaction method and apparatus |
| CN101929788A (en) * | 2010-09-15 | 2010-12-29 | 中国科学院理化技术研究所 | Device for preparing liquefied natural gas from oxygen-containing coal bed gas |
| CN102504900A (en) * | 2011-10-20 | 2012-06-20 | 辽宁哈深冷气体液化设备有限公司 | Equipment for preparing liquefied natural gas (LNG) from coke oven gas and method thereof |
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