CN105254463B - The method that methane is extracted from containing methane, hydrogen, the gaseous mixture of nitrogen - Google Patents
The method that methane is extracted from containing methane, hydrogen, the gaseous mixture of nitrogen Download PDFInfo
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- CN105254463B CN105254463B CN201510696863.1A CN201510696863A CN105254463B CN 105254463 B CN105254463 B CN 105254463B CN 201510696863 A CN201510696863 A CN 201510696863A CN 105254463 B CN105254463 B CN 105254463B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
- F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
- F25J3/0204—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the feed stream
- F25J3/0209—Natural gas or substitute natural gas
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
- F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
- F25J3/0228—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream
- F25J3/0233—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream separation of CnHm with 1 carbon atom or more
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
- F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
- F25J3/0228—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream
- F25J3/0257—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream separation of nitrogen
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J2200/00—Processes or apparatus using separation by rectification
- F25J2200/04—Processes or apparatus using separation by rectification in a dual pressure main column system
- F25J2200/06—Processes or apparatus using separation by rectification in a dual pressure main column system in a classical double column flow-sheet, i.e. with thermal coupling by a main reboiler-condenser in the bottom of low pressure respectively top of high pressure column
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J2210/00—Processes characterised by the type or other details of the feed stream
- F25J2210/06—Splitting of the feed stream, e.g. for treating or cooling in different ways
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J2215/00—Processes characterised by the type or other details of the product stream
- F25J2215/04—Recovery of liquid products
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J2230/00—Processes or apparatus involving steps for increasing the pressure of gaseous process streams
- F25J2230/30—Compression of the feed stream
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J2240/00—Processes or apparatus involving steps for expanding of process streams
- F25J2240/02—Expansion of a process fluid in a work-extracting turbine (i.e. isentropic expansion), e.g. of the feed stream
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J2270/00—Refrigeration techniques used
- F25J2270/12—External refrigeration with liquid vaporising loop
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J2270/00—Refrigeration techniques used
- F25J2270/66—Closed external refrigeration cycle with multi component refrigerant [MCR], e.g. mixture of hydrocarbons
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- Thermal Sciences (AREA)
- General Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Separation By Low-Temperature Treatments (AREA)
Abstract
The invention discloses a kind of method that methane is extracted from containing methane, hydrogen, the gaseous mixture of nitrogen：Unstripped gas is divided into two strands of air-flow A, air-flow B, air-flow A, which enters, enters high-pressure tower progress rectifying separation after main heat exchanger cooling；Air-flow B enters after main heat exchanger cooling certain phase, is extracted out from heat exchanger middle part, is sent directly into lower pressure column rectifying after expanded machine decompression refrigeration cool-down, bottom of towe obtains product liquid methane.Or, unstripped gas enters main heat exchanger and is cooled to after certain phase, is divided into two strands of air-flow A and air-flow B：Air-flow A, which continues after into main heat exchanger cooling to enter after high-pressure tower carries out rectifying separation, the expanded machine decompression refrigeration cool-downs of air-flow B, is sent directly into lower pressure column rectifying, and bottom of towe obtains product liquid methane.The present invention can directly obtain the normal pressure liquified natural gas that purity is more than 98%, and product can substantially reduce energy consumption, methane recovery is up to 99.5%, and rate of recovery of nitrogen is up to 99%, and the nitrogen after re-heat can be used as industrial nitrogen without re-liquefied.
Description
Technical field
The present invention relates to a kind of method that methane is extracted from containing methane, hydrogen, the gaseous mixture of nitrogen.
Background technology
Coal bed gas, synthesis ammonia relief gas, coal upgrading pyrolysis tail gas etc. are the gaseous mixture containing elements such as methane, hydrogen, nitrogen, its
Main component includes：CO2、H2、CH4、CO、H2O、N2And other hydro carbons and sulfide.
(mainly CH in current gaseous mixture4、H2And N2) methane separation technology has membrane separation process, pressure swing adsorption method.UF membrane
Though technology is simple to operate, energy consumption is low, investment cost is larger, and separating effect is poor, though pressure swing adsorption method is convenient and swift, by
Approached in the absorption property of methane and nitrogen, cause the rate of recovery of product gas relatively low, and be difficult to separate CH4And N2, and cryogenic rectification
Technology can be directly separated out the methane and nitrogen of high-purity.
The content of the invention
Goal of the invention：The purpose of the present invention existing extracts first aiming at above-mentioned from containing methane, hydrogen, the gaseous mixture of nitrogen
Deficiency present in the method for alkane can effectively extract the deep cooling high-low pressure tower rectification process of methane there is provided new.
Technical scheme：The invention provides a kind of method that methane is extracted from containing methane, hydrogen, the gaseous mixture of nitrogen：
Unstripped gas is divided into two strands of air-flows, main air (air-flow A), secondary air flow (air-flow B)：Air-flow A enters master
Enter high-pressure tower after heat exchanger cooling and carry out rectifying separation；Air-flow B enters after main heat exchanger cooling certain phase, from heat exchanger
Portion is extracted out, is sent directly into lower pressure column rectifying after expanded machine decompression refrigeration cool-down, bottom of towe obtains product liquid methane.
Or, unstripped gas enters main heat exchanger and is cooled to after certain phase, is divided into two strands of air-flows, main air (air-flow A)
With secondary air flow (air-flow B)：Air-flow A continues to enter high-pressure tower progress rectifying separation after into main heat exchanger cooling, and air-flow B is through swollen
Lower pressure column rectifying is sent directly into after swollen machine decompression refrigeration cool-down, bottom of towe obtains product liquid methane.
The methane-rich liquid of lower pressure column tower reactor of the present invention enters condenser/evaporator, and evaporation section is steamed as the rising of lower pressure column
Vapour, unvaporized portion is drawn from condenser/evaporator side, after being subcooled through subcooler, obtains product liquified natural gas.Obtained production
Product are the normal pressure liquified natural gas of purity more than 98%, and product can substantially reduce energy consumption, methane recovery is up to without re-liquefied
99.5%.
Rich nitrogen that low pressure column overhead of the present invention is obtained with from high-pressure tower for uncooled rich nitrogen together re-heat after,
Drawn as product nitrogen gas.Specifically, the nitrogen that low pressure column overhead obtains purity more than 99.5% can be as industry after re-heat
Nitrogen is used.Drawing liquid nitrogen (high purity 99.8%) continuation cools down deutomerite and flows into lower pressure column from high-pressure tower, is used as returning for lower pressure column
Flow liquid.
Other part cold can be provided or nitrogen expansion mechanism cold by azeotrope compression circularly cooling in process of the present invention
Circulate to provide.
In the present invention, operating condition is：Low pressure pressure tower is that (more than (gauge pressure), high pressure pressure tower is 0.4MPa to 0.01MPa
More than (gauge pressure).Stricter to equipment requirement because pressure is higher, the present invention is not influenceing the premise of separating effect and recovery rate
Under, directly enter lower pressure column after extracting partial raw gas expansion, make full use of the rectifying potentiality of lower pressure column, and high pressure can be substantially reduced
The load of tower, so as to mitigate the manufacture difficulty of high-pressure tower.
The present invention's can be realized by following two specific technical schemes：
Scheme one：
Coal upgrading pyrolysis tail gas is passed through into desulfurization and decarburization, removes water, takes off after heavy hydrocarbon and trace impurity, into methanation unit,
Obtained tail gas is as unstripped gas.
Unstripped gas is divided into two strands of air-flow A, air-flow B.
Wherein air-flow A enters main heat exchanger E1, through exchanging heat, and after unstripped gas partial liquefaction, into high-pressure tower T1 bottom, enters
The preliminary rectifying separation of row.Wherein the volatile components rich in nitrogen are upward along tower height, and gaseous flow stock is drawn in high-pressure tower T1 tower tops
(i.e. air-flow G), into condenser/evaporator E4, carries out partial condensation, condensed liquid stream (i.e. air-flow C) is subcooled by one
Decompression, which enters, after device E2 supercoolings continues rectifying in the middle part of lower pressure column.
Another gang of air-flow B therein enters main heat exchanger E1, and raw material expanding machine EXP1 is entered after cooling, after decompression cooling,
It is air-flow E with high-pressure tower tower bottoms, into lower pressure column T2 middle parts, is made with high-pressure tower T1 overhead condensation liquids air-flow (i.e. air-flow C)
For overhead reflux liquid, lower pressure column T2 distillation process is carried out, the methane-rich liquid of lower pressure column tower reactor enters condenser/evaporator E4 mono-
Side, the rich nitrogen for the high pressure tower top that the evaporator E4 opposite sides that are condensed is heated to part evaporation, and evaporation section is used as lower pressure column
Upflowing vapor, unvaporized portion from condenser/evaporator E4 sides draw air-flow (i.e. air-flow H), after being subcooled through subcooler as produce
Product liquified natural gas.
Scheme two：
Coal upgrading pyrolysis tail gas is passed through into desulfurization and decarburization, removes water, takes off after heavy hydrocarbon and trace impurity, into methanation unit,
Obtained tail gas is as unstripped gas.
Unstripped gas enters main heat exchanger and is cooled to after certain phase, is divided into main air and secondary air flow.
Main air continues to enter high-pressure tower progress rectifying separation after into main heat exchanger cooling, and secondary air flow is expanded
Rectifying in the middle part of lower pressure column is sent directly into after machine decompression refrigeration cool-down, bottom of towe obtains product methane.
Described main air enters main heat exchanger (E1), through heat exchange, after unstripped gas cooling or partial liquefaction, into height
The bottom of tower (T1) is pressed, preliminary rectifying separation is carried out；Wherein the volatile components rich in nitrogen are upward along tower height, in high-pressure tower
(T1) tower top draws gaseous flow stock, into condenser/evaporator (E4), carries out partial condensation, and condensed liquid stream passes through one
Decompression, which enters, after subcooler (E2) supercooling continues rectifying in the middle part of lower pressure column.
Described secondary air flow enters raw material expanding machine (EXP1), after decompression cooling, with high-pressure tower tower bottoms, enters
In the middle part of lower pressure column (T2), using high-pressure tower (T1) overhead condensation liquid air-flow as overhead reflux liquid, the rectifying of lower pressure column (T2) is carried out
Process, the methane-rich liquid of lower pressure column tower reactor enters condenser/evaporator (E4) side, what the evaporator that is condensed (E4) opposite side came
The rich nitrogen of high pressure tower top is heated to part evaporation, and evaporation section is as the upflowing vapor of lower pressure column, and unvaporized portion is from condensation
Air-flow is drawn in evaporator (E4) side, and product liquified natural gas is used as after being subcooled through subcooler.
Beneficial effect：1, the present invention can directly obtain the normal pressure liquified natural gas that purity is more than 98%, and product need not
It is re-liquefied, energy consumption can be substantially reduced, methane recovery is up to 99.5%.The nitrogen that purity is more than 99%, nitrogen can be obtained
Gas recovery rate is up to 99%, and the nitrogen after re-heat can be used as industrial nitrogen.
2, the present invention, using the rich nitrogen supercooling lower pressure column bottom product liquid methane of low temperature of low pressure column overhead, is that product is carried
For enough degree of supercoolings, while the thick methane of high pressure tower bottom is subcooled, to reduce the temperature that liquid enters lower pressure column, reflux ratio is improved,
Improve rectifying ability.
3, the present invention directly enters low on the premise of separating effect and recovery rate is not influenceed after extracting partial raw gas expansion
Tower is pressed, the rectifying potentiality of lower pressure column is taken full advantage of, substantially reduces the load of high-pressure tower, so that the making for mitigating high-pressure tower is difficult
Degree.
Brief description of the drawings
Fig. 1 is the schematic flow sheet of the embodiment of the present invention 1；
Fig. 2 is the schematic flow sheet of the embodiment of the present invention 2.
Embodiment：
Below in conjunction with the accompanying drawings, the embodiment to the present invention is further illustrated,
Embodiment 1
As shown in figure 1, in Fig. 1, the represented equipment of each mark is as follows：P1- unstripped gas expanding machine pressurized ends；P2- is mixed
Close refrigerant cycle compressor；E1- main heat exchangers；E2- subcoolers；E3- azeotrope coolers；E4- condenser/evaporators；EXP1-
Raw material expander end；T1- high-pressure towers；T2- lower pressure columns；FL- gas-liquid separators.
The represented air-flow of each mark is as follows：The unstripped gas of the laggard high-pressure tower of air-flow A- precoolings；After air-flow B- compression-expansions
Enter the unstripped gas of lower pressure column；The high pressure nitrogen overhead condensate liquid into lower pressure column is subcooled in air-flow C-；Air-flow D- enters the high pressure of lower pressure column
The thick methane of tower bottom of towe；Air-flow E- is used for the low pressure nitrogen overhead of re-heat；The gaseous flow stock that air-flow F- high pressures column overhead is drawn；Air-flow
G- bottom products LNG.
Handled coal upgrading pyrolysis tail gas in the present embodiment, main component includes：CO2、H2、CH4、CO、H2O、N2And its
His hydro carbons and sulfide.
The gas is passed through into desulfurization and decarburization, removed water, is taken off after heavy hydrocarbon and trace impurity, into methanation unit, obtained tail
Gas is as unstripped gas, and unstripped gas tolerance is 25000Nm3/ h, pressure about 20bar, are divided into two strands of air-flow A, air-flow B by unstripped gas.
Wherein 15000Nm3/ h is used to directly enter lower pressure column rectifying, remaining 10000Nm after compressing precooling expansion3/ h is through the laggard high pressure of deep cooling
Tower rectifying.
Wherein air-flow A enters main heat exchanger E1, through exchanging heat, and after unstripped gas partial liquefaction, into high-pressure tower T1 bottom, enters
The preliminary rectifying separation of row.Wherein the volatile components rich in nitrogen are upward along tower height, and gaseous flow stock is drawn in high-pressure tower T1 tower tops,
That is air-flow F, into condenser/evaporator E4, carries out partial condensation, condensed liquid stream C is after subcooler E2 supercoolings
Decompression, which enters, continues rectifying in the middle part of lower pressure column, lower pressure column T2 nitrogen overhead air-flows E enters main heat exchanger E1, supplement is provided for process
Low temperature cold.
Another gang of air-flow B therein enters main heat exchanger E1 after unstripped gas expanding machine pressurized end P1 superchargings, after cooling
Into raw material expanding machine EXP1, after decompression cooling, and high-pressure tower tower bottoms, i.e. air-flow D, into the middle part of lower pressure column T2, with height
Press tower T1 overhead condensation liquid air-flow C (57500Nm3/ h) as overhead reflux liquid, carry out lower pressure column T2 distillation process, lower pressure column
The methane-rich liquid of tower reactor enters condenser/evaporator E4 sides, the rich nitrogen for the high pressure tower top that the evaporator E4 opposite sides that are condensed come
Be heated to part evaporation, evaporation section as lower pressure column upflowing vapor, unvaporized portion from condenser/evaporator E4 sides draw
Air-flow G, is used as product liquified natural gas after being subcooled through subcooler.
Unstripped gas and each step gas parameter, as shown in table 1 below in embodiment 1：
Table 1
| Gas after methanation | Unstripped gas after dehydration | Low pressure tower top richness nitrogen | Product LNG | |
| Flow (Nm3/h) | 300000 | 250000 | 206000 | 45630 |
| Temperature (DEG C) | 20 | 20 | -193 | -180 |
| Pressure (barA) | ~20 | ~20 | ~1.3 | ~1.4 |
| Constitute (mol%) | ||||
| CH4 | 14.57 | 17.72 | 9ppm | 98 |
| H2 | 0.429 | 0.522 | 0.64 | 0 |
| N2 | 67.18 | 81.75 | 99.36 | 2 |
| H2O | 17.82 | 0 | 0 | 0 |
| CO | 31ppm | 38ppm | 41ppm | 22ppm |
Embodiment 2
As shown in Fig. 2 in fig. 2, the represented equipment of each mark is as follows：P1- unstripped gas expanding machine pressurized ends；P2- is mixed
Close refrigerant cycle compressor；E1- main heat exchangers；E2- subcoolers；E3- azeotrope coolers；E4- condenser/evaporators；EXP1-
Raw material expander end；T1- high-pressure towers；T2- lower pressure columns；FL- gas-liquid separators.
The represented air-flow of each mark is as follows：The unstripped gas of the laggard high-pressure tower of air-flow A- precoolings；Air-flow B- expansions are laggard low
Press the unstripped gas of tower；The high pressure nitrogen overhead condensate liquid into lower pressure column is subcooled in air-flow C-；Air-flow D- enters the high-pressure tower tower of lower pressure column
The thick methane in bottom；Air-flow E- is used for the low pressure nitrogen overhead of re-heat；The gaseous flow stock that air-flow F- high pressures column overhead is drawn；Air-flow G- towers
Bottom product LNG.
Handled gas in the present embodiment, main component includes：CO2、H2、CH4、CO、H2O、N2And other hydro carbons and sulphur
Compound.After unstripped gas enters in the middle part of main heat exchanger, it is divided into two strands, air-flow A and air-flow B, air-flow A continue after cooling into main heat exchanger E1
Into high-pressure tower T1 bottoms, preliminary rectifying separation is carried out, wherein the volatile components rich in nitrogen are upward along tower height, in high-pressure tower
T1 tower tops draw gaseous flow stock, i.e. air-flow F into condenser/evaporator E4, carries out partial condensation, condensed liquid stream C
Decompression, which enters, after subcooler E2 supercoolings continues rectifying in the middle part of lower pressure column, lower pressure column T2 nitrogen overhead air-flows E is changed into master
Hot device E1, the low temperature cold of supplement is provided for process.
Lower pressure column T2 rectifying is sent directly into after air-flow B expanded machine EXP1 decompression refrigeration cool-downs, and high-pressure tower tower bottoms, i.e.,
Air-flow D, into lower pressure column T2 middle parts, using high-pressure tower T1 overhead condensation liquid air-flow C as overhead reflux liquid, carries out lower pressure column T2
Distillation process, the methane-rich liquid of lower pressure column tower reactor enters condenser/evaporator E4 sides, and the evaporator E4 opposite sides that are condensed come
The rich nitrogen of high pressure tower top be heated to part evaporation, evaporation section is as the upflowing vapor of lower pressure column, and unvaporized portion is from cold
Air-flow G is drawn in solidifying evaporator E4 sides, and product liquified natural gas is used as after being subcooled through subcooler.
Unstripped gas and each step gas parameter, as shown in table 2 below in embodiment 2：
Table 2
| Gas after methanation | Unstripped gas after dehydration | Low pressure tower top richness nitrogen | Product LNG | |
| Flow (Nm3/h) | 300000 | 250000 | 206600 | 45600 |
| Temperature (DEG C) | 20 | 20 | -193 | -162 |
| Pressure (barA) | ~20 | ~20 | ~1.3 | ~1.4 |
| Constitute (mol%) | ||||
| CH4 | 14.57 | 17.72 | 9ppm | 98 |
| H2 | 0.429 | 0.522 | 0.64 | 0 |
| N2 | 67.18 | 81.75 | 99.36 | 2 |
| H2O | 17.82 | 0 | 0 | 0 |
| CO | 31ppm | 38ppm | 40ppm | 28ppm |
Claims (6)
1. a kind of method that methane is extracted from containing methane, hydrogen, the gaseous mixture of nitrogen, it is characterised in that unstripped gas is divided into two strands
Air-flow, main air enters after main heat exchanger cooling, and feeding high-pressure tower carries out rectifying separation；Secondary air flow enters main heat exchange
After device cooling certain phase, extracted out from heat exchanger middle part, essence in the middle part of lower pressure column is sent directly into after expanded mechanism cold decrease temperature and pressure
Evaporate, bottom of towe obtains product methane；
Described main air enters main heat exchanger (E1), through heat exchange, after unstripped gas cooling or partial liquefaction, into high-pressure tower
(T1) bottom, carries out preliminary rectifying separation；Wherein the volatile components rich in nitrogen are upward along tower height, in high-pressure tower (T1) tower
Gaseous flow stock is drawn on top, into condenser/evaporator (E4), carries out partial condensation, and condensed liquid stream passes through a subcooler
(E2) decompression, which enters, after being subcooled continues rectifying in the middle part of lower pressure column；
Described secondary air flow enters and enters raw material expanding machine (EXP1) after main heat exchanger (E1) cooling, after decompression cooling, with
High-pressure tower tower bottoms, into lower pressure column (T2) middle part, as overhead reflux liquid, is entered using high-pressure tower (T1) overhead condensation liquid air-flow
The distillation process of row lower pressure column (T2), the methane-rich liquid of lower pressure column tower reactor enters condenser/evaporator (E4) side, and be condensed steaming
The rich nitrogen for the high pressure tower top that hair device (E4) opposite side comes is heated to part evaporation, and evaporation section is steamed as the rising of lower pressure column
Vapour, unvaporized portion draws air-flow from condenser/evaporator (E4) side, and product liquified natural gas is used as after being subcooled through subcooler.
2. according to the method described in claim 1, it is characterised in that during other part cold can be followed by azeotrope compression
Ring refrigeration is provided or nitrogen expansion mechanism SAPMAC method is provided.
3. according to the method described in claim 1, it is characterised in that low pressure pressure tower is more than 0.01MPa, high pressure pressure tower is
More than 0.4MPa.
4. a kind of method that methane is extracted from containing methane, hydrogen, the gaseous mixture of nitrogen, it is characterised in that unstripped gas enters main heat exchanger
After cooling, it is divided into main air and secondary air flow：Main air continues into high-pressure tower to enter after into main heat exchanger cooling
Row rectifying is separated, and is sent directly into rectifying in the middle part of lower pressure column after the expanded machine decompression refrigeration cool-down of secondary air flow, bottom of towe is produced
Product methane；
Described main air enters main heat exchanger (E1), through heat exchange, after unstripped gas cooling or partial liquefaction, into high-pressure tower
(T1) bottom, carries out preliminary rectifying separation；Wherein the volatile components rich in nitrogen are upward along tower height, in high-pressure tower (T1) tower
Gaseous flow stock is drawn on top, into condenser/evaporator (E4), carries out partial condensation, and condensed liquid stream passes through a subcooler
(E2) decompression, which enters, after being subcooled continues rectifying in the middle part of lower pressure column；
Described secondary air flow enters raw material expanding machine (EXP1), after decompression cooling, and high-pressure tower tower bottoms, into low pressure
In the middle part of tower (T2), using high-pressure tower (T1) overhead condensation liquid air-flow as overhead reflux liquid, the distillation process of lower pressure column (T2) is carried out,
The methane-rich liquid of lower pressure column tower reactor enters condenser/evaporator (E4) side, the high-pressure tower that the evaporator that is condensed (E4) opposite side comes
The rich nitrogen on top is heated to part evaporation, and evaporation section is as the upflowing vapor of lower pressure column, and unvaporized portion is from condenser/evaporator
(E4) air-flow is drawn in side, and product liquified natural gas is used as after being subcooled through subcooler.
5. method according to claim 4, it is characterised in that during other part cold can be followed by azeotrope compression
Ring refrigeration is provided or nitrogen expansion mechanism SAPMAC method is provided.
6. method according to claim 4, it is characterised in that low pressure pressure tower is more than 0.01MPa, high pressure pressure tower is
More than 0.4MPa.
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| US6182468B1 (en) * | 1999-02-19 | 2001-02-06 | Ultimate Process Technology | Thermodynamic separation of heavier components from natural gas |
| GB0111961D0 (en) * | 2001-05-16 | 2001-07-04 | Boc Group Plc | Nitrogen rejection method |
| GB0216537D0 (en) * | 2002-07-16 | 2002-08-28 | Boc Group Plc | Nitrogen rejection method and apparatus |
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