CN105066582A - Method for producing liquefied methane gas through pipe network pressure - Google Patents
Method for producing liquefied methane gas through pipe network pressure Download PDFInfo
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- CN105066582A CN105066582A CN201510416552.5A CN201510416552A CN105066582A CN 105066582 A CN105066582 A CN 105066582A CN 201510416552 A CN201510416552 A CN 201510416552A CN 105066582 A CN105066582 A CN 105066582A
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- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 title claims abstract description 180
- 238000004519 manufacturing process Methods 0.000 title abstract description 4
- 239000007789 gas Substances 0.000 claims abstract description 82
- 239000003345 natural gas Substances 0.000 claims abstract description 27
- 238000000034 method Methods 0.000 claims abstract description 25
- OTMSDBZUPAUEDD-UHFFFAOYSA-N Ethane Chemical compound CC OTMSDBZUPAUEDD-UHFFFAOYSA-N 0.000 claims abstract description 8
- 239000003507 refrigerant Substances 0.000 claims description 48
- 239000012808 vapor phase Substances 0.000 claims description 25
- 239000012071 phase Substances 0.000 claims description 19
- 239000007788 liquid Substances 0.000 claims description 14
- 239000002994 raw material Substances 0.000 claims description 13
- 238000000926 separation method Methods 0.000 claims description 13
- 239000007791 liquid phase Substances 0.000 claims description 11
- 238000001816 cooling Methods 0.000 claims description 7
- 230000001105 regulatory effect Effects 0.000 claims description 7
- 238000005057 refrigeration Methods 0.000 claims description 6
- 239000008246 gaseous mixture Substances 0.000 claims description 5
- 239000003949 liquefied natural gas Substances 0.000 claims description 5
- 239000002253 acid Substances 0.000 claims description 3
- 238000002156 mixing Methods 0.000 claims description 3
- 239000008239 natural water Substances 0.000 claims description 3
- 239000000446 fuel Substances 0.000 abstract description 5
- 238000000746 purification Methods 0.000 abstract description 2
- 230000000717 retained effect Effects 0.000 abstract description 2
- 238000013461 design Methods 0.000 description 6
- 238000005516 engineering process Methods 0.000 description 6
- 230000000694 effects Effects 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- 238000004364 calculation method Methods 0.000 description 3
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000004880 explosion Methods 0.000 description 2
- 238000010926 purge Methods 0.000 description 2
- 238000011144 upstream manufacturing Methods 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 238000012512 characterization method Methods 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000002596 correlated effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- TVMXDCGIABBOFY-UHFFFAOYSA-N octane Chemical compound CCCCCCCC TVMXDCGIABBOFY-UHFFFAOYSA-N 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 239000001294 propane Substances 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
- 230000008961 swelling Effects 0.000 description 1
- 230000009897 systematic effect Effects 0.000 description 1
- 230000000007 visual effect Effects 0.000 description 1
Classifications
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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
- F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
- F25J1/0002—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the fluid to be liquefied
- F25J1/0022—Hydrocarbons, e.g. natural gas
-
- 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
- F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
- F25J1/003—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production
- F25J1/0032—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using the feed stream itself or separated fractions from it, i.e. "internal refrigeration"
- F25J1/0035—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using the feed stream itself or separated fractions from it, i.e. "internal refrigeration" by gas expansion with extraction of work
- F25J1/0037—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using the feed stream itself or separated fractions from it, i.e. "internal refrigeration" by gas expansion with extraction of work of a return stream
-
- 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
- F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
- F25J1/02—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process
- F25J1/0201—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process using only internal refrigeration means, i.e. without external refrigeration
-
- 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
- F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
- F25J1/02—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process
- F25J1/0228—Coupling of the liquefaction unit to other units or processes, so-called integrated processes
- F25J1/0232—Coupling of the liquefaction unit to other units or processes, so-called integrated processes integration within a pressure letdown station of a high pressure pipeline system
-
- 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
- F25J2220/00—Processes or apparatus involving steps for the removal of impurities
- F25J2220/60—Separating impurities from natural gas, e.g. mercury, cyclic hydrocarbons
- F25J2220/62—Separating low boiling components, e.g. He, H2, N2, Air
-
- 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
- F25J2220/00—Processes or apparatus involving steps for the removal of impurities
- F25J2220/60—Separating impurities from natural gas, e.g. mercury, cyclic hydrocarbons
- F25J2220/64—Separating heavy hydrocarbons, e.g. NGL, LPG, C4+ hydrocarbons or heavy condensates in general
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Mechanical Engineering (AREA)
- 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 relates to the technical field of liquefaction of natural gas and particularly relates to a method for producing liquefied methane gas through pipe network pressure. According to the method, pressure energy retained after purification of high-pressure natural gas is used for producing the liquefied methane gas, and the liquefied methane gas of high purity and high quality can be obtained; besides, as automobile high-performance fuel, ethane and components above which are produced simultaneously still have certain applicability and a high economy property. The method for producing the liquefied methane gas through pipe network pressure is simple in step, few in use device and capable of not needing external cold sources and improving the energy use rate effectively.
Description
Technical field
The present invention relates to liquefaction Technology of Natural Gas field, particularly relate to a kind of method producing liquefied methane gas, relate more specifically to a kind of method utilizing the liquefied methane gas of pipe network pressure energy high-purity.
Background technology
Along with the continuous growth of China's natural gas user's request, the NG Pipeline Construction development of China is swift and violent.Gao Long-distance Transmission Pipeline generally adopts high-pressure delivery, the transfering natural gas from the west to the east of China, Shan Jingxian, the peaceful interconnection in Ji etc. the design pressure of the nationwide gas transmission line of trunk all reach 10MPa, the design pressure of the second west to east gas pipeline project reaches 12MPa especially, and external modern age, high-level long-distance transport pipes design pressure was generally at more than 10MPa.
Huge pressure energy contained by high pressure gas pipeline net, but the terminal use in downstream is low with atmospheric pressure, and the receiving station in each city and voltage regulating station will carry out pressure regulation according to the pressure demand of downstream user, ensure that it normally uses.But the natural gas of high pressure can discharge huge energy, these energy effectively do not utilize, and cause the waste of energy.
Liquefied methane gas (English full name: LiquefiedMethaneGas, english abbreviation: LMG), can be defined as methane content higher than 98%, ethane content be less than 0.1% and propane content lower than 0.02% the liquid form of methane gas.Seldom have the introduction about LMG at home, but development is very fast abroad.Particularly, as motor vehicle fuel, LMG, compared with the natural gas of high pressure, has the following advantages: 1. the security of LMG is higher, and the burning-point of methane is 680 DEG C, higher than the burning-point of the natural gas of high pressure, and explosion limit is 5%-15%; And the natural gas of high pressure is due to containing certain ethane and above component thereof, its explosion limit wider range.2. the component of LMG is purer, and discharge clean environment firendly, LMG is than the natural gas clean environment firendly more of high pressure.3. good in economic efficiency, LMG can raise the efficiency 5%-10% as motor vehicle fuel than the natural gas of high pressure, and power performance promotes 20%.The advantages such as 4. to have octane number high for LMG, and the capability of antidetonance is good, stay in grade, and engine life is long.
Based on above-mentioned advantage, need to produce liquefied methane gas, as high performance motor vehicle fuel, but the system pressure difference that utilizes existed at present produces the device of liquefied natural gas, only can produce liquefied natural gas, and can not produce out liquefied methane gas.
Summary of the invention
(1) technical problem that will solve
The technical problem to be solved in the present invention there is provided a kind of method and system utilizing pipe network pressure energy to produce liquefied methane gas, can make full use of the energy that high-pressure natural gas discharges in pressure regulation process and obtain highly purified liquefied methane gas.
(2) technical scheme
In order to solve the problems of the technologies described above, the invention provides a kind of method utilizing pipe network pressure energy to produce liquefied methane gas, comprising the steps:
Step S1: shunting: one is for high pressure refrigerant high-pressure natural gas to be divided into two strands, and one is the high pressure feed producing liquefied natural gas;
Step S2: precooling: high pressure refrigerant and high pressure feed in First Heat Exchanger by precooling;
Step S3: the gas-liquid separation of high pressure refrigerant: the high pressure refrigerant after precooling in step S2 is carried out gas-liquid separation in the second separator, obtains high pressure vapor refrigerant and liquid phase refrigerant;
Step S4: the swell refrigeration of high pressure vapor refrigerant: be low-pressure vapor phase refrigerant by the high pressure vapor refrigerant expansion step-down obtained in step s3;
Step S5: the degree of depth cooling of high pressure feed: the high pressure feed after step S2 precooling is carried out degree of depth cooling by the second heat exchanger;
Step S6: high pressure feed reducing pressure by regulating flow: cooled for step S5 degree of depth high pressure feed is carried out reducing pressure by regulating flow by first throttle valve, becomes middle pressure unstripped gas;
Step S7: middle pressure unstripped gas gas-liquid separation: press unstripped gas to carry out gas-liquid separation in the first separator in obtaining in step S6, obtain middle pressure phase feed and liquid phase feed;
Step S8: middle pressure phase feed swell refrigeration: press phase feed expansion step-down to be low-pressure vapor phase raw material in obtaining in step S7;
Step S9: methane is purified: the liquid phase feed that step S7 obtains is passed into domethanizing column, isolates methane gas;
Step S10: methane gas cools: the methane gas obtained in step S9 lowered the temperature through the 3rd heat exchanger;
Step S11: methane throttling is lowered the temperature: by cooled for step S10 methane gas, lowered the temperature by second throttle step-down, generates liquefied methane gas;
Step S12: provide cold and mixing: the step S8 low-pressure vapor phase raw material obtained provides cold for the second heat exchanger, enters afterwards after blender mixes with the low-pressure vapor phase refrigerant that step S4 obtains and provides cold by the 3rd heat exchanger and First Heat Exchanger successively.
Further, in abovementioned steps S1, when the acid content in described high-pressure natural gas and water content higher time, described high-pressure natural gas first passes through pretreatment unit before shunting.
Further, decompressor can be adopted in step S4 and step S8 to carry out expansion step-down.
Further, when the quantity of aforementioned swollen machine is multiple, be connected in series between described decompressor.
Further, air wave refrigerating device can be adopted in step S4 and step S8 to carry out expansion step-down.
Further, in abovementioned steps S9, described domethanizing column can also extract ethane and above component thereof.
Further, the gaseous mixture of the low-pressure vapor phase raw material in abovementioned steps S12 and described low-pressure vapor phase refrigerant is elevated to by the temperature after described First Heat Exchanger and is greater than 0 DEG C.
(3) beneficial effect
Technique scheme of the present invention has following beneficial effect:
The invention provides a kind of method utilizing pipe network pressure energy to produce liquefied methane gas, the pressure energy retained after carrying out purified treatment to high-pressure natural gas is utilized to produce liquefied methane gas, the liquefied methane gas of high-purity high-quality can be obtained, as the high performance fuel of automobile, the ethane simultaneously produced and above component thereof still have certain applicability and larger economy, and this flowage structure is simple simultaneously, and equipment is few, do not need external source, effectively improve energy utilization rate.
Accompanying drawing explanation
Fig. 1 is that the present invention utilizes pipe network pressure energy to produce the process flow diagram of liquefied methane gas.
Wherein, 1: the high pressure gas after purification; 2: current divider; 3: First Heat Exchanger; 4: the second heat exchangers; 5: first throttle valve; 6: the first separators; 7: domethanizing column; 8: normal pressure LMG knockout drum; 9: the three heat exchangers; 10: second throttle; 11: the first decompressors; 12: the second separators; 13: the second decompressors; 14: blender; 15: low-pressure pipe network.
Detailed description of the invention
Below in conjunction with drawings and Examples, embodiments of the present invention are described in further detail.Following examples for illustration of the present invention, but can not be used for limiting the scope of the invention.
In describing the invention, it should be noted that, except as otherwise noted, the implication of " multiple " is two or more; Term " on ", D score, "left", "right", " interior ", " outward ", " front end ", " rear end ", " head ", the orientation of the instruction such as " afterbody " or position relationship be based on orientation shown in the drawings or position relationship, only the present invention for convenience of description and simplified characterization, instead of indicate or imply that the device of indication or element must have specific orientation, with specific azimuth configuration and operation, therefore can not be interpreted as limitation of the present invention.In addition, term " first ", " second ", " the 3rd " etc. only for describing object, and can not be interpreted as instruction or hint relative importance.
In describing the invention, also it should be noted that, unless otherwise clearly defined and limited, term " installation ", " being connected ", " connection " should be interpreted broadly, and such as, can be fixedly connected with, also can be removably connect, or connect integratedly; Can be mechanical connection, also can be electrical connection; Can be directly be connected, also indirectly can be connected by intermediary.For the ordinary skill in the art, visual concrete condition understands above-mentioned term concrete meaning in the present invention.
In describing the invention, " high pressure " is higher than 6MPa; " middle pressure " is lower than feed gas pressure higher than 1MPa; Low end finger is about 0.2-0.8MPa; Normal pressure refers to atmospheric pressure.
A kind of method utilizing pipe network pressure energy to produce liquefied methane gas that the present embodiment provides, comprises the steps:
Step S1: shunting: one is for high pressure refrigerant high-pressure natural gas to be divided into two strands, and one is the high pressure feed producing liquefied natural gas;
Step S2: precooling: high pressure refrigerant and high pressure feed in First Heat Exchanger by precooling;
Step S3: the gas-liquid separation of high pressure refrigerant: the high pressure refrigerant after precooling in step S2 is carried out gas-liquid separation in the second separator, obtains high pressure vapor refrigerant and liquid phase refrigerant;
Step S4: the swell refrigeration of high pressure vapor refrigerant: be low-pressure vapor phase refrigerant by the high pressure vapor refrigerant expansion step-down obtained in step s3;
Step S5: the degree of depth cooling of high pressure feed: the high pressure feed after step S2 precooling is carried out degree of depth cooling by the second heat exchanger;
Step S6: high pressure feed reducing pressure by regulating flow: cooled for step S5 degree of depth high pressure feed is carried out reducing pressure by regulating flow by first throttle valve, becomes middle pressure unstripped gas;
Step S7: middle pressure unstripped gas gas-liquid separation: press unstripped gas to carry out gas-liquid separation in the first separator in obtaining in step S6, obtain middle pressure phase feed and liquid phase feed;
Step S8: middle pressure phase feed swell refrigeration: press phase feed expansion step-down to be low-pressure vapor phase raw material in obtaining in step S7;
Step S9: methane is purified: the liquid phase feed that step S7 obtains is passed into domethanizing column, isolates methane gas; Domethanizing column can also extract ethane and above component thereof, and the ethane of production and above component thereof still have certain applicability and larger economy;
Step S10: methane gas cools: the methane gas obtained in step S9 lowered the temperature through the 3rd heat exchanger;
Step S11: methane throttling is lowered the temperature: by cooled for step S10 methane gas, lowered the temperature by second throttle step-down, generates liquefied methane gas;
Step S12: provide cold and mixing: the step S8 low-pressure vapor phase raw material obtained provides cold for the second heat exchanger, enters afterwards after blender mixes with the low-pressure vapor phase refrigerant that step S4 obtains and provides cold by the 3rd heat exchanger and First Heat Exchanger successively.
Wherein, in step S1, when the acid content in described high-pressure natural gas and water content higher time, described high-pressure natural gas first passes through pretreatment unit before shunting.
Decompressor can be adopted in step S4 and step S8 to carry out expansion step-down.When the quantity of decompressor is multiple, be connected in series between described decompressor.In addition, air wave refrigerating device can be adopted in step S4 and step S8 to substitute decompressor and carry out expansion step-down.
Wherein, the inlet pressure of step S1 Raw gas is greater than 6MPa, the pressure of step S4 mesolow gas phase refrigerant and step S8 mesolow phase feed is 0.2-0.8MPa, and the gaseous mixture of the low-pressure vapor phase raw material in step S12 and described low-pressure vapor phase refrigerant is elevated to by the temperature after described First Heat Exchanger and is greater than 0 DEG C.
Here prove its feasibility with technology Calculation, table 1 is the gas composition form of the pure natural gas of high pressure, carries out technology Calculation by gas composition wherein.Wherein, correlated condition comprises: feeding temperature 20 DEG C, and high pressure purge natural gas feed pressure is 10MPa, and it is normal pressure that highly purified liquefied methane gas stores pressure.
The pure feeding gas composition of table 1 high pressure
Technology Calculation obtains each gas parameter in table 2:
The liquefaction flow path systematic parameter that table 2 designs
In table 2, the concrete composition of each gas is as shown in table 3:
The each logistics composition of table 3
In sum, what the present embodiment provided utilizes pipe network pressure energy to produce the technique of liquefied methane gas, can produce higher degree liquefied methane gas.
The present invention realizes the method by the system utilizing pipe network pressure energy and produce liquefied methane gas, this technological design can make full use of the pressure energy of pipe network, avoid pressure energy to waste in pressure regulation process, make methane liquefaction and purify all to be undertaken by the energy of high pressure purge gas self generation.
Concrete, as shown in Figure 1, be the system that method that the present embodiment utilizes pipe network pressure energy to produce liquefied methane gas is applied.
First separator 6 is press feed gas separator in one, and the first separator 6 pressure is lower than feed gas pressure, higher than 1MPa.Its effect presses unstripped gas to carry out gas-liquid separation in after First Heat Exchanger 3, second heat exchanger 4 secondary pre-cold-peace first throttle valve 5 throttling expansion step-down.The middle pressure phase feed low-temperature receiver as a supplement separated, after low pressure is reduced in the first decompressor 11 expansion, be followed successively by the second heat exchanger 4, the 3rd heat exchanger 9, First Heat Exchanger 3 provide low-temperature receiver, the liquid phase feed separated enters domethanizing column 7 and isolates methane.
Second separator 12 is high pressure refrigerant separator, and the heavy hydrocarbon may separated out in the high pressure refrigerant after First Heat Exchanger 3 precooling is isolated in its effect, and the second decompressor 13 for downstream works the condition created.
The object of normal pressure LMG knockout drum 8 is the gas phases isolated in liquefied methane gas, and the normal pressure for liquefied methane gas stores prepares.
The effect of First Heat Exchanger 3 is the high pressure feed shunted at its upstream of precooling and high pressure refrigerant.Its low-temperature receiver mixes the gaseous mixture of rear formation from low-pressure vapor phase raw material and the mixed device 14 of low-pressure vapor phase refrigerant.
The effect of the second heat exchanger 4 is further precooling high pressure feed.Its low-temperature receiver to be expanded the low-pressure vapor phase raw material formed after step-down by the first decompressor 11 from the isolated middle pressure phase feed of downstream first separator 6.
The effect of the 3rd heat exchanger 9 is that precooling is from the isolated methane gas of domethanizing column 7.Its low-temperature receiver mixes the gaseous mixture of rear formation from low-pressure vapor phase raw material and the mixed device 14 of low-pressure vapor phase refrigerant.
High pressure refrigerant gas is expand into low pressure by the second decompressor 13, and produce cold, low-pressure vapor phase refrigerant is followed successively by the 3rd heat exchanger 9, First Heat Exchanger 3 provides cold.
First decompressor 11 will separate middle pressure phase feed by middle compression swelling to low pressure from the first separator 6, and low-pressure vapor phase raw material is followed successively by the second heat exchanger 4, the 3rd heat exchanger 9, First Heat Exchanger 3 provide cold.
Unstripped gas produces liquefied methane gas main flow: the high pressure feed after being shunted in current divider 2 by the high pressure gas 1 after purifying is successively by after the precooling of First Heat Exchanger 3, second heat exchanger 4, by high pressure throttling extremely middle pressure in first throttle valve 5, enter the first separator 6, the liquid phase feed separated by the first separator 6 enters domethanizing column 7 and isolates methane gas, again after the 3rd heat exchanger 9 further cooling, be throttled to normal pressure by second throttle 10, obtain liquefied methane gas.
Refrigerant flow path: refrigerant is made up of two parts, the high pressure refrigerant after being shunted by high-pressure natural gas and press phase feed from the first separator 6 is separated.High pressure refrigerant after high-pressure natural gas shunting and converging at blender 14 after pressing phase feed to be depressured to low pressure respectively through different approaches from the first separator 6 is separated, is followed successively by the 3rd heat exchanger 9, First Heat Exchanger 3 enters low-pressure pipe network 15 after providing cold.In the upstream of blender 14, high pressure refrigerant have passed through the expansion process of pre-cold-peace second decompressor 13 at First Heat Exchanger 3; From the first separator 6 is separated, press phase feed after the first decompressor 11 expands, for the second heat exchanger 4 provides cold.In sum, high-pressure natural gas is divided into high pressure feed and high pressure refrigerant by the present invention, optimize heat-exchanging process, by high pressure refrigerant gas with press phase feed to be depressurized to low pressure respectively through decompressor from MP separator is separated, to provide cold for flow process.
Embodiments of the invention provide in order to example with for the purpose of describing, and are not exhaustively or limit the invention to disclosed form.Many modifications and variations are apparent for the ordinary skill in the art.Selecting and describing embodiment is in order to principle of the present invention and practical application are better described, and enables those of ordinary skill in the art understand the present invention thus design the various embodiments with various amendment being suitable for special-purpose.
Claims (7)
1. utilize pipe network pressure energy to produce a method for liquefied methane gas, it is characterized in that, comprise the steps:
Step S1: shunting: one is for high pressure refrigerant high-pressure natural gas to be divided into two strands, and one is the high pressure feed producing liquefied natural gas;
Step S2: precooling: high pressure refrigerant and high pressure feed in First Heat Exchanger by precooling;
Step S3: the gas-liquid separation of high pressure refrigerant: the high pressure refrigerant after precooling in step S2 is carried out gas-liquid separation in the second separator, obtains high pressure vapor refrigerant and liquid phase refrigerant;
Step S4: the swell refrigeration of high pressure vapor refrigerant: be low-pressure vapor phase refrigerant by the high pressure vapor refrigerant expansion step-down obtained in step s3;
Step S5: the degree of depth cooling of high pressure feed: the high pressure feed after step S2 precooling is carried out degree of depth cooling by the second heat exchanger;
Step S6: high pressure feed reducing pressure by regulating flow: cooled for step S5 degree of depth high pressure feed is carried out reducing pressure by regulating flow by first throttle valve, becomes middle pressure unstripped gas;
Step S7: middle pressure unstripped gas gas-liquid separation: press unstripped gas to carry out gas-liquid separation in the first separator in obtaining in step S6, obtain middle pressure phase feed and liquid phase feed;
Step S8: middle pressure phase feed swell refrigeration: press phase feed expansion step-down to be low-pressure vapor phase raw material in obtaining in step S7;
Step S9: methane is purified: the liquid phase feed that step S7 obtains is passed into domethanizing column, isolates methane gas;
Step S10: methane gas cools: the methane gas obtained in step S9 lowered the temperature through the 3rd heat exchanger;
Step S11: methane throttling is lowered the temperature: by cooled for step S10 methane gas, lowered the temperature by second throttle step-down, generates liquefied methane gas;
Step S12: provide cold and mixing: the step S8 low-pressure vapor phase raw material obtained provides cold for the second heat exchanger, to enter afterwards after blender mixes with the low-pressure vapor phase refrigerant that step S4 obtains successively by the 3rd heat exchanger and First Heat Exchanger to provide cold.
2. the method utilizing pipe network pressure energy to produce liquefied methane gas according to claim 1, it is characterized in that: in described step S1, when the acid content in described high-pressure natural gas and water content higher time, described high-pressure natural gas first passes through pretreatment unit before shunting.
3. the method utilizing pipe network pressure energy to produce liquefied methane gas according to claim 1, is characterized in that: decompressor can be adopted in step S4 and step S8 to carry out expansion step-down.
4. the method utilizing pipe network pressure energy to produce liquefied methane gas according to claim 3, is characterized in that: when the quantity of described decompressor is multiple, be connected in series between described decompressor.
5. the method utilizing pipe network pressure energy to produce liquefied methane gas according to claim 1, is characterized in that: air wave refrigerating device can be adopted in step S4 and step S8 to carry out expansion step-down.
6. the method utilizing pipe network pressure energy to produce liquefied methane gas according to claim 1, is characterized in that: in described step S9, and described domethanizing column can also extract ethane and above component thereof.
7. the method utilizing pipe network pressure energy to produce liquefied methane gas according to claim 1, is characterized in that: the gaseous mixture of the low-pressure vapor phase raw material in described step S12 and described low-pressure vapor phase refrigerant is elevated to by the temperature after described First Heat Exchanger and is greater than 0 DEG C.
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