CN102492505B - Two-section type single loop mixed refrigerant natural gas liquefaction process and device - Google Patents
Two-section type single loop mixed refrigerant natural gas liquefaction process and device Download PDFInfo
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- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 title claims abstract description 140
- 239000003507 refrigerant Substances 0.000 title claims abstract description 113
- 239000003345 natural gas Substances 0.000 title claims abstract description 66
- 238000000034 method Methods 0.000 title claims abstract description 52
- 230000008569 process Effects 0.000 title claims abstract description 44
- 238000001816 cooling Methods 0.000 claims abstract description 48
- 239000007788 liquid Substances 0.000 claims abstract description 32
- 238000007906 compression Methods 0.000 claims abstract description 31
- 230000006835 compression Effects 0.000 claims abstract description 30
- 238000000926 separation method Methods 0.000 claims abstract description 11
- 239000003949 liquefied natural gas Substances 0.000 claims abstract description 8
- 239000007791 liquid phase Substances 0.000 claims description 30
- 239000012808 vapor phase Substances 0.000 claims description 25
- 235000009508 confectionery Nutrition 0.000 claims description 19
- -1 16-22% Chemical compound 0.000 claims description 13
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 8
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 claims description 8
- QWTDNUCVQCZILF-UHFFFAOYSA-N isopentane Chemical compound CCC(C)C QWTDNUCVQCZILF-UHFFFAOYSA-N 0.000 claims description 8
- OTMSDBZUPAUEDD-UHFFFAOYSA-N Ethane Chemical compound CC OTMSDBZUPAUEDD-UHFFFAOYSA-N 0.000 claims description 4
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 claims description 4
- AFABGHUZZDYHJO-UHFFFAOYSA-N dimethyl butane Natural products CCCC(C)C AFABGHUZZDYHJO-UHFFFAOYSA-N 0.000 claims description 4
- 229910052757 nitrogen Inorganic materials 0.000 claims description 4
- 239000001294 propane Substances 0.000 claims description 4
- 239000007789 gas Substances 0.000 abstract description 13
- 238000005265 energy consumption Methods 0.000 abstract description 3
- 239000000203 mixture Substances 0.000 description 34
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 23
- 238000005057 refrigeration Methods 0.000 description 14
- 239000012071 phase Substances 0.000 description 11
- 239000012530 fluid Substances 0.000 description 5
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- 229910052782 aluminium Inorganic materials 0.000 description 3
- 238000005493 welding type Methods 0.000 description 3
- 230000002159 abnormal effect Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 235000019628 coolness Nutrition 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 230000008859 change Effects 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 239000000306 component Substances 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 239000008358 core component Substances 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000002309 gasification Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 238000002203 pretreatment Methods 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 230000011218 segmentation Effects 0.000 description 1
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Abstract
The invention relates to a two-section type single loop mixed refrigerant natural gas liquefaction process and a device. The process comprises the following steps: conducting two-section compression cooling on mixed refrigerant, enabling the mixed refrigerant to be in gas state after first section compression cooling, conducting first gas-liquid separation after second section compression cooling, obtaining gas state refrigerant and liquid state refrigerant; enabling the liquid state refrigerant to enter an ice chest for cooling and then throttling, cooling and returning to the ice chest for providing cooling amount of a high temperature position; enabling the gas state refrigerant to enter the ice chest for cooling to a low temperature and then throttling, cooling and returning to the ice chest for providing cooling amount of a low temperature position; enabling the gas state refrigerant to be converged with the liquid state refrigerant returning to the ice chest after throttling to improve the cooling amount of the high temperature position; conducting two-section type compression cooling on the mixed refrigerant providing the cooling amount to enter next circulation; enabling natural gas to enter the ice chest for cooling, and then obtaining liquefied natural gas products after throttling. The invention further provides a liquefied natural gas device used in the process. The process is simple in process, and has the advantages of high liquefaction rate, low energy consumption and the like.
Description
Technical field
The present invention relates to a kind of natural gas liquefaction process and equipment, relate in particular to a kind of two-part single loop mixed refrigerant natural gas liquefaction process and equipment.
Background technology
Sweet natural gas is a kind of fossil energy of high-quality cleaning, and after natural gas via liquefaction, it is original 1/625 that volume is about, thereby be convenient to store and transportation.Compare with pipeline gas, natural gas liquids (LNG) in the exploitation in scattered gas field, marginal gas field, aspect the introduction of the exploitation of the utilization of coal-seam gas, offshore natural gas and overseas Sweet natural gas, have irreplaceable effect.
Natural gas liquefaction has compact cascade type refrigeration cycle, mix refrigerant refrigeration cycle and expander refrigeration to circulate three kinds.Wherein mix refrigerant circulation (MRC) flow process is relatively simple, and energy utilization efficiency is high, energy consumption is low, thereby adopts the most general.Especially single loop mix refrigerant liquefaction process (SMR) is applied very extensive in middle-size and small-size liquefying plant.But single loop mix refrigerant liquefaction process, in order to keep higher liquefaction efficiency, contains more heavy constituent conventionally in its cryogen, thereby when segmentation compression intercooling, have partially liq cryogen and condense.In order to process this part of cryogen, the method that adds cryogenic fluid pump can be adopted, but moving parts can be increased, make technical process become complicated.
BV PRICO@technique is a kind of existing liquefaction process, this technique is to adopt two sections of compressions cooling, after intercooling, cryogen is gas-liquid two-phase, wherein, vapor phase refrigerant enters two sections of suctions port of compressor, and liquid phase refrigerant is promoted its pressure and again mixed with the cryogen of two sections of compressor outlets by a special cryogenic fluid pump arranging.Because cooled gas-liquid two-phase cryogen between this process section need be processed respectively, liquid phase refrigerant needs cryogenic fluid pump to carry, its technical process more complicated.
Chinese patent application 201010252812.7 discloses a kind of method of utilizing mix refrigerant natural gas liquids, and Chinese utility model patent 200920099685.4 discloses a kind of equipment of mix refrigerant liquefaction flow path of simplification.Aforesaid method and equipment are to adopt two sections of compressions cooling equally, and after intercooling, cryogen is gas-liquid two-phase, and wherein vapor phase refrigerant enters two sections of suctions port of compressor, and liquid phase refrigerant arranges an independent runner and enters ice chest, and by independent J-T valve throttling refrigeration.Simultaneously, in above-mentioned technical scheme, two sections of cooled cryogens of compression of compressor are equally also gas-liquid two-phase, the second knockout drum need to be set, and the liquid phase refrigerant that generally still needs a less cryogenic fluid pump that the second gas-liquid separator is obtained delivers to ice chest top, its liquefaction process is more complicated also.
Chinese utility model patent 200920092366.0 discloses a kind of three sections of hybrid refrigeration natural gas liquefaction devices, this device is to adopt two sections of compressions cooling equally, after intercooling, cryogen is gas-liquid two-phase, wherein vapor phase refrigerant enters two sections of suctions port of compressor, liquid phase refrigerant arranges an independent runner and enters ice chest, and by independent J-T valve throttling refrigeration.Simultaneously in the disclosed technical scheme of this patent, two sections of cooled cryogens of compression of compressor are equally also gas-liquid two-phase, the second knockout drum need to be set, this patent is again that gas, the liquid two-phase cryogen that the second knockout drum obtains is provided with respectively runner, and adopt respectively independently J-T valve throttling refrigeration, thereby one have three cryogen runners, three J-T valves, its technique is more complicated also.
Chinese utility model patent 201020218282.X discloses a kind of device of natural gas liquids that adopts single mixing medium to freeze to come, and what this device adopted is three grades of compressions, and flow process is more complicated.
Summary of the invention
For solving the problems of the technologies described above, the object of the present invention is to provide a kind of natural gas liquefaction process, keeping, on the basis of single loop mixed refrigerant process higher-energy level of efficiency, providing a kind of technical process more to simplify, can reduce or eliminate the technical process of gas-liquid two-phase azeotrope assignment of traffic problem.
The present invention also provides a kind of natural gas liquefaction process equipment, adopts aluminum braze welding type plate-fin cryogenic heat exchanger as ice chest, and this equipment can be used in above-mentioned natural gas liquefaction process provided by the present invention.
For achieving the above object, first the present invention provides a kind of two-part single loop mixed refrigerant natural gas liquefaction process, and it comprises the following steps:
To mix refrigerant carry out two sections of compressions cooling after, carry out a gas-liquid separation, obtain vapor phase refrigerant and liquid phase refrigerant, wherein, after first paragraph compression is cooling, mix refrigerant is gaseous state;
Make liquid phase refrigerant enter the cooling rear throttling cooling of ice chest, and return to the cold that ice chest provides high potential temperature;
Make vapor phase refrigerant enter ice chest and be cooled to throttling cooling after low temperature, return to the cold that first ice chest provides low-temperature level, then with throttling after return to ice chest liquid phase refrigerant converge, the cold of high potential temperature is provided jointly;
Cooling to providing mix refrigerant after the cold of high potential temperature to carry out two sections of compressions, carry out the next one and circulate;
Sweet natural gas enter ice chest cooling after, then obtain liquefied natural gas product through throttling.
According to concrete technical scheme of the present invention, preferably, above-mentioned natural gas liquefaction process can comprise following concrete steps:
To mix refrigerant carry out two sections of compressions cooling after, carry out a gas-liquid separation, obtain vapor phase refrigerant and liquid phase refrigerant, wherein, after first paragraph compression is cooling, mix refrigerant is gaseous state;
Throttling cooling after making liquid phase refrigerant enter ice chest to be cooled to-50 ℃ to-65 ℃, and return to ice chest, after mixing with the vapor phase refrigerant of returning after throttling, provide together the cold of high potential temperature section;
After making vapor phase refrigerant enter ice chest to be cooled to-151 ℃ to-162 ℃, throttling cooling, returns to the cold that first ice chest provides low-temperature level, and it, is converged with the liquid phase refrigerant returning after throttling by rewarming after-50 ℃ to-65 ℃, and the cold of high potential temperature is provided jointly;
Cooling to providing mix refrigerant after the cold of high potential temperature to carry out two sections of compressions, carry out the next one and circulate;
Sweet natural gas enters ice chest and is cooled to-151 ℃ or lower temperature, then obtains liquefied natural gas product through throttling.
In above-mentioned natural gas liquefaction process, after mix refrigerant provides cold in ice chest, complete a refrigeration cycle, then re-start two sections of compressions and start next refrigeration cycle.Preferably, the molar percentage of the mix refrigerant adopting consists of: methane, 16-22%, ethene or ethane, 33-39%, propane, 15-21%, iso-pentane, 12-18%, nitrogen, 8-14%; The molar percentage sum of all components meets 100%.More preferably, the molar percentage of described mix refrigerant consists of: methane, 18.89%, ethene or ethane, 36.08%, propane, 18.37%, iso-pentane, 15.42%, nitrogen, 11.24%.According to the difference of the composition of raw natural gas, the composition of mix refrigerant can change in above-mentioned scope.
In above-mentioned natural gas liquefaction process, preferably, two sections of cooling referring to of compression that adopt: mix refrigerant is compressed to 600-1000kPa (being preferably 847kPa), be cooled to again 25 ℃-45 ℃ or room temperature, now, mix refrigerant is all gas phase, and then second-compressed is to 3500-4500kPa (being preferably 4080kPa), then is cooled to 25 ℃-45 ℃ or room temperature.Mix refrigerant is cooling through two sections of compressions, and wherein, cooling (first paragraph is cooling) carried out afterwards in centre, and mix refrigerant still remains gas phase, does not need to carry out gas-liquid separation, has also just saved the difficulty that vapor phase refrigerant and liquid phase refrigerant are processed respectively.Meanwhile, in two sections of compression process of cooling, intercooling temperature can be adjusted according to actual condition, can be by the control of heat-eliminating medium is adjusted to intercooling temperature.When operating mode occurs when abnormal, after the compression through first paragraph is cooling, may produce the liquid phase refrigerant of minute quantity, for this part a small amount of liquid phase refrigerant, as long as an electric heater is set, it is heated and is vaporized just passablely, also small part can be drawn this part liquid phase refrigerant is heated and is vaporized from the vapor phase refrigerant of the second compressor outlet.
In above-mentioned natural gas liquefaction process, preferably, the pressure-controlling of vapor phase refrigerant after throttling is 350-450kPa, more preferably 420kPa.
In above-mentioned natural gas liquefaction process, preferably, Sweet natural gas, vapor phase refrigerant and liquid phase refrigerant all enter from the top of ice chest, and in ice chest, mobile and temperature reduces gradually from top to bottom.The top of ice chest is high potential temperature (or claiming high potential temperature section), and bottom is low-temperature level (or claiming low-temperature level section).Sweet natural gas, before entering ice chest, can purify pre-treatment according to conventional mode, removes impurity wherein.
The present invention also provides a kind of natural gas liquefaction device, and it comprises the first suction tank, the first compressor, the first water cooler, the second suction tank, the second compressor, the second water cooler, knockout drum, ice chest, first throttle valve, the second throttling valve, wherein,
Above-mentioned ice chest has four runners, is respectively first flow, the second runner, the 3rd runner and the 4th runner;
The outlet of the first suction tank is connected by pipeline with the entrance of the first compressor;
The outlet of the first compressor is connected by pipeline with the entrance of the first water cooler;
The outlet of the first water cooler is connected by pipeline with the entrance of the second suction tank;
The outlet of the second suction tank is connected by pipeline with the entrance of the second compressor;
The outlet of the second compressor is connected by pipeline with the entrance of the second water cooler;
The outlet of the second water cooler is connected by pipeline with the entrance of knockout drum;
The pneumatic outlet of knockout drum is connected by pipeline with the entrance of the second runner of ice chest, and the liquid exit of knockout drum is connected by pipeline with the entrance of the 3rd runner of ice chest;
The outlet of the second runner is connected by pipeline with the entrance of the 4th flow field end, and the pipeline between the two is provided with first throttle valve, and first throttle valve is positioned at the outside of ice chest;
The outlet of the 3rd runner is connected by pipeline with the entrance at the 4th runner middle part, and the pipeline between the two is provided with the second throttling valve, and the second throttling valve is positioned at the outside of ice chest;
The outlet of the 4th runner is connected by pipeline with the entrance of the first suction tank;
The first flow of ice chest is natural-gas transfer pipeline.
In above-mentioned natural gas liquefaction device, the device that each concrete device can adopt this area conventionally to adopt, wherein, the first compressor and the first water cooler are cooling for mix refrigerant being carried out to first paragraph compression; The second compressor and the second water cooler are cooling for mix refrigerant being carried out to second segment compression; Knockout drum is for carrying out gas-liquid separation to compressing cooling mix refrigerants through two sections; Ice chest is for the cold and hot exchange of mix refrigerant and Sweet natural gas, so that natural gas liquefaction; First throttle valve and the second throttling valve are respectively used to vapor phase refrigerant and liquid phase refrigerant to carry out throttling cooling.
In above-mentioned natural gas liquefaction device, preferably, the ingress of the first flow of ice chest is connected with Sweet natural gas input channel, and, this Sweet natural gas input channel is provided with purifying device for natural gas and the 3rd throttling valve, the exit of the first flow of ice chest is connected with Sweet natural gas output channel, and this Sweet natural gas output channel is provided with product valve.
In above-mentioned natural gas liquefaction device, preferably, the ice chest adopting is plate-fin ice chest, and the core component of this plate-fin ice chest is aluminum braze welding type plate-fin cryogenic heat exchanger.Two-part single loop mixed refrigerant natural gas liquefaction process provided by the present invention and equipment are suitable for adopting plate-fin ice chest, but also can adopt the ice chest of other structural shape.
In above-mentioned natural gas liquefaction device, preferably, the compressor adopting (the first compressor, the second compressor) is the centrifugal mix refrigerant compressor of compression.
In above-mentioned natural gas liquefaction device, preferably, the water cooler adopting (the first water cooler, the second water cooler) is air-cooler and/or watercooler etc.
In above-mentioned natural gas liquefaction device, preferably, ice chest is divided into high potential temperature section and low-temperature level section, first flow, the second runner and the 4th runner have distribution in high potential temperature section and low-temperature level Duan Jun, the 3rd runner is only distributed in high potential temperature section, the end outlet of the 4th runner is positioned at low-temperature level section end, and the centre entrance of the 4th runner is between low-temperature level section and high potential temperature section.High potential temperature section is positioned at the top of ice chest, and in this region, the temperature of Sweet natural gas is higher.Low-temperature level section is positioned at the bottom of ice chest, and in this region, the temperature relatively-high temperature position section of Sweet natural gas decreases.The high temperature of high potential temperature section is for the low temperature of low-temperature level section, and in fact, the temperature of two sections is all below normal temperature.
In above-mentioned natural gas liquefaction device, preferably, this natural gas liquefaction device also comprises a cryogen reservoir, and it is connected on the pipeline between the outlet of the 4th runner and the entrance of the first suction tank, and this cryogen reservoir is for adding or supplementary mix refrigerant to equipment.
Under nominal situation, through first paragraph, compressing cooling mix refrigerant is pure vapor phase refrigerant.In order to prevent that a small amount of liquid producing under unusual service condition from entering the second compressor of mix refrigerant and compressor is produced and damaged herein, the second suction tank arranging herein can, by a small amount of liquid separation, be protected whole Processes and apparatus; In technical process, do not need for liquid refrigerant extra setting procedure and circulation again, a small-sized electric heater is only set at the bottom of this second suction tank tank or pipeline that a diameter is less is set and the vapor phase refrigerant of the second compressor outlet place high temperature is passed into the liquid cryogen gasification that makes the minute quantity that produces under abnormal conditions.In above-mentioned natural gas liquefaction device, preferably, the second suction tank is provided with an electric heater, while having liquid phase refrigerant to gather in the second suction tank for its heating is vaporized, or, the second suction tank is connected with the outlet of described the second compressor by pipeline, while having liquid phase refrigerant to gather in the second suction tank for introduce leave the second compressor outlet place a small amount of vapor phase refrigerant for the liquid phase refrigerant of the second suction tank is heated and is vaporized.
Through two sections of compressions cooled vapor phase refrigerant and liquid phase refrigerants after gas-liquid separation, be delivered to respectively the corresponding runner entrance at ice chest top, and adopt respectively two throttle valve control, so both avoided employing cryogenic fluid pump to carry liquid phase refrigerant, meanwhile, only adopt two sections of cooling flow processs, only adopt a gas-liquid separation just can be divided into two strands of refrigeration agents, compare with liquefaction process and the syllogic single loop mix refrigerant liquefaction process of twice gas-liquid separation of existing needs, its energy consumption level quite and technical process is simpler.
The flow process of natural gas liquefaction process provided by the present invention and equipment is fairly simple, and output investment ratio is lower, has that liquefied fraction is high, low power consumption and other advantages simultaneously.
Accompanying drawing explanation
The structural representation of the natural gas liquefaction device that Fig. 1 provides for embodiment 1.
Main drawing reference numeral explanation:
The first suction tank 1 first compressor 2 first water coolers 3
The second suction tank 4 second compressor 5 second water coolers 6
Knockout drum 7 plate-fin ice chest 8 first throttle valves 9
The second throttling valve 10 cleaners 11 the 3rd throttling valve 12
Embodiment
For technical characterictic of the present invention, object and beneficial effect being had more clearly, understand, existing technical scheme of the present invention is carried out to following detailed description, but can not be interpreted as restriction that can practical range of the present invention.
Embodiment 1
The present embodiment provides a kind of two-part single loop mix refrigerant natural gas liquefaction device, its structure as shown in Figure 1, this natural gas liquefaction device comprises: the first suction tank 1, the first compressor 2, the first water cooler 3, the second suction tank 4, the second compressor 5, the second water cooler 6, knockout drum 7, plate-fin ice chest 8, first throttle valve 9, the second throttling valve 10, wherein:
Plate-fin ice chest 8 adopts aluminum braze welding type plate-fin cryogenic heat exchanger, and it is provided with four runners, and as shown in Figure 1, the leftmost side is first flow (natural-gas transfer pipeline), is then followed successively by from left to right the second runner, the 3rd runner, the 4th runner;
The first compressor 2 and the second compressor 5 all adopt two sections of centrifugal hybrid refrigeration machine compressors of compression;
The first water cooler 3 and the second water cooler 6 all adopt air cooler;
The outlet of the first suction tank 1 is connected by pipeline with the entrance of the first compressor 2;
The outlet of the first compressor 2 is connected by pipeline with the entrance of the first water cooler 3;
The outlet of the first water cooler 3 is connected by pipeline with the entrance of the second suction tank 4;
The outlet of the second suction tank 4 is connected by pipeline with the entrance of the second compressor 5;
The outlet of the second compressor 5 is connected by pipeline with the entrance of the second water cooler 6;
The outlet of the second water cooler 6 is connected by pipeline with the entrance of knockout drum 7;
The pneumatic outlet of knockout drum 7 is connected by pipeline with the entrance of the second runner of plate-fin ice chest 8, and the liquid exit of knockout drum 7 is connected by pipeline with the entrance of the 3rd runner of plate-fin ice chest 8;
The outlet of the second runner is connected by pipeline with the entrance of the 4th flow field end, and the pipeline between the two is provided with first throttle valve 9, and first throttle valve 9 is positioned at the outside of plate-fin ice chest 8;
The outlet of the 3rd runner is connected by pipeline with the entrance at the 4th runner middle part, and the pipeline between the two is provided with the outside that the second throttling valve 10, the second throttling valve 10 are positioned at plate-fin ice chest 8;
The outlet of the 4th runner is connected by pipeline with the entrance of the first suction tank 1;
The ingress of the first flow of plate-fin ice chest 8 is connected with Sweet natural gas input channel, and, this Sweet natural gas input channel is provided with natural gas purifier 11 and the 3rd throttling valve 12, the exit of the first flow of plate-fin ice chest 8 is connected with Sweet natural gas output channel, and this Sweet natural gas output channel is provided with product valve 13 and holder 14.
The present embodiment provides a kind of two-part single loop mixed refrigerant natural gas liquefaction process, and the technique that its equipment that is employing embodiment 1 provides carries out natural gas liquefaction, comprises following concrete steps:
The mix refrigerant that by pressure is 350kPa to 450kPa (being preferably 420kPa) is compressed in 600kPa to 1000kPa scope and (is preferably 847kPa) by the first compressor 2, by the first water cooler 3, be cooled to 25 ℃ to 45 ℃ (relevant with envrionment temperature) again, by the second suction tank 4, sucked again, then enter the second compressor 5 and be compressed to 3500kPa to 4500kPa (being preferably 4080kPa), then be cooled to 25 ℃ to 45 ℃ (relevant with envrionment temperature) by the second water cooler 6;
Now mix refrigerant is gas-liquid two-phase, input knockout drum 7 carries out after gas-liquid separation, obtain vapor phase refrigerant and liquid phase refrigerant, the two is processed respectively: liquid phase refrigerant enters in plate-fin ice chest 8 by the 3rd runner of plate-fin ice chest 8, and leave plate-fin ice chest 8 after being chilled in advance-50 ℃ to-65 ℃, after the second throttling valve 10 throttling coolings, return to plate-fin ice chest 8, after mixing with the vapor phase refrigerant of returning after throttling, provide together the cold of high potential temperature section; Vapor phase refrigerant is after leaving knockout drum 8, the second runner by plate-fin ice chest 8 enters in plate-fin ice chest 8, and leave plate-fin ice chest 8 after being cooled to-151 ℃ to-162 ℃, after the 9 throttling coolings of first throttle valve, returning to plate-fin ice chest 8 provides the cold of low-temperature level section, self, is converged with the liquid phase refrigerant returning after throttling to the temperature (within the scope of 50 ℃ to-65 ℃) identical with liquid phase refrigerant precooling temperature by rewarming, and the cold of high potential temperature section is provided jointly;
Mix refrigerant after rewarming returns to the first suction tank 1, completes refrigeration cycle one time, and starts to enter refrigeration cycle next time;
Unstripped gas is at cleaner 11 purification removal impurity and after the 3rd throttling valve 12, first flow by plate-fin ice chest 8 enters plate-fin ice chest 8, with refrigeration agent heat exchange, unstripped gas is cooled to-151 ℃ to-162 ℃ and liquefaction, by obtaining LNG product after 13 throttlings of product valve, enter holder (for example LNG basin) 14, complete gas deliquescence process.
In above-mentioned technique, the molar percentage of the mix refrigerant adopting consists of: methane, 16-22% (being preferably 18.89%), ethene or ethane, 3-39% (being preferably 36.08%), propane, 15-21% (being preferably 18.37%), iso-pentane, 12-18% (being preferably 15.42%), nitrogen, 8-14% (being preferably 11.24%).
Above-described specific embodiment; object of the present invention, technical scheme and beneficial effect are further described; institute is understood that; the foregoing is only specific embodiments of the invention; the protection domain being not intended to limit the present invention; within the spirit and principles in the present invention all, any modification of making, be equal to replacement, improvement etc., within all should being included in protection scope of the present invention.
Claims (2)
1. a two-part single loop mixed refrigerant natural gas liquefaction process, it comprises the following steps:
To mix refrigerant carry out two sections of compressions cooling after, carry out a gas-liquid separation, obtain vapor phase refrigerant and liquid phase refrigerant, wherein, after first paragraph compression is cooling, mix refrigerant is gaseous state;
Throttling cooling after making liquid phase refrigerant enter ice chest to be cooled to-50 ℃ to-65 ℃, and return to ice chest, after mixing with the vapor phase refrigerant of returning after throttling, provide together the cold of high potential temperature section; The pressure-controlling of described vapor phase refrigerant after throttling is 350-450kPa;
After making vapor phase refrigerant enter ice chest to be cooled to-151 ℃ to-162 ℃, throttling cooling, returns to the cold that first ice chest provides low-temperature level, and it, is converged with the liquid phase refrigerant returning after throttling by rewarming after-50 ℃ to-65 ℃, and the cold of high potential temperature is provided jointly;
Cooling to providing mix refrigerant after the cold of high potential temperature to carry out two sections of compressions, carry out the next one and circulate;
Sweet natural gas enters ice chest and is cooled to-151 ℃ or lower temperature, then obtains liquefied natural gas product through throttling;
Wherein, the molar percentage of described mix refrigerant consists of: methane, 16-22%, and ethene or ethane, 33-39%, propane, 15-21%, iso-pentane, 12-18%, nitrogen, 8-14%, the molar percentage sum of all components meets 100%;
Described two sections of cooling referring to of compression: mix refrigerant is compressed to 600-1000kPa, then is cooled to 25 ℃-45 ℃ or room temperature, then second-compressed is to 3500-4500kPa, then is cooled to 25 ℃-45 ℃ or room temperature.
2. natural gas liquefaction process according to claim 1, wherein, described Sweet natural gas, described vapor phase refrigerant and described liquid phase refrigerant all enter from the top of described ice chest, flow from top to bottom and temperature reduces gradually in described ice chest.
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| CN103411337A (en) * | 2013-08-02 | 2013-11-27 | 北京麦科直通石化工程设计有限公司 | System and method for improving refrigerating capacity of olefin separating device |
| CN103673501B (en) * | 2013-12-11 | 2015-09-09 | 辽宁哈深冷气体液化设备有限公司 | The preparation method of high-efficiency multi-stage throttling natural gas liquefaction device and liquefied natural gas |
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