CN1004228B - To liquidize natural gas by two mixed refrigerants - Google Patents
To liquidize natural gas by two mixed refrigerants Download PDFInfo
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- CN1004228B CN1004228B CN85101713.4A CN85101713A CN1004228B CN 1004228 B CN1004228 B CN 1004228B CN 85101713 A CN85101713 A CN 85101713A CN 1004228 B CN1004228 B CN 1004228B
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Abstract
The present invention relates to a method for liquefying natural gas by using two closed cycle polycomponent refrigerants and equipment thereof. A low degree refrigerant carried out cooling through indirect heat exchange and liquefies the natural gas; a high degree refrigerant carried out cooling through multi-stage indirect heat exchange and liquefies partially the low degree refrigerant so make the high degree refrigerant to carry out phase separation so that light refrigerant components carry out final refrigeration for minimum temperature; a liquid phase obtained through separation are divided into two parts, and then the liquid phase is expanded for refrigeration so as to avoid multi-stage rapid separation; heavy components are used for low degree refrigeration.
Description
The present invention is that relevant natural gas is rich in the liquifying method of methane gas stream with other.More precisely, the present invention is relevant method with two kinds of mixed cooling medium liquefied natural gas, and the refrigerant of this method employing has the high efficiency flow track, can be used for liquefied natural gas or is rich in the air-flow of methane.
Recovery and utilization are rich in the natural gas that methane gas stream need liquefy as the natural gas of economic fuels sources with other, so that be transported to the place to use economically from the production site with gas.Obviously, the liquefaction of a large amount of natural gases can increase energy consumption.For the price that makes commercially available natural gas is suitable, liquefaction process must be saved energy as far as possible.
In addition,, must improve the efficient of natural gas liquefaction process, so that required fuel quantity and energy reduces to minimum when liquefying in view of various forms of energy consumptions all can increase cost.
Under certain conditions, as the temperature low (being lower than 18.33 ℃) of cooling water, when the machine of chilling unit is uneven if compression load and the driver of the chilling unit that is used for liquefying or be used to turns round, can reduce the liquefaction efficiency that one pack system circulates.Main energy consumption is a compression load in the liquefaction process.Liquifying method is the variation of acclimatization condition easily, that is to say, not only at the environment of gentleness and the environment of cold, as in the nearly Arctic in the world, this liquifying method must be effectively, is exactly in the environment of sweltering heat, under the operating environment condition, this liquifying method also must be effective.This weather conditions mainly are Temperature Influence to cooling water to the influence of liquefaction process, this cooling water can be used for producing the used refrigeration processes of liquefied natural gas, because the difference of changes of seasons or each department weather, the temperature of used cooling water has sizable difference, thereby can produce uneven in the various refrigerant cycles of mixing circulation.
For the efficient liquifying method of the various changes in environmental conditions of easy adaptation is provided, many tests have been carried out.In United States Patent (USP) 4112700, proposed to be used to handle the liquifying method of natural gas, adopted two kinds of closed-circuit refrigeration agent streams in this method with liquefied natural gas.First high-order precooling refrigerant cycles is used for cooled natural gas with multistep.First kind of high-order precooling refrigerant is carried out multistep is separated, wherein its effect be the lightweight part of loopback refrigerant to be used for recirculation, the heavy part of refrigerant then is retained to cool off under lower temperature.First kind of high-order precooling refrigerant also is used to cool off second kind of low level refrigerant.Second kind of low level refrigerant carries out the liquefaction of natural gas with a single step.The shortcoming of this method is: high-order precooling refrigerant carries out more and more lower sub-cooled with more and more heavier component.This and desired high efficiency cooling means run in the opposite direction.And this second kind or low level refrigerant are to be used for liquefied natural gas with a single step, rather than carry out this liquefaction with multistep.
United States Patent (USP) 4274849 discloses the liquifying method that is rich in methane gas, and this method adopts two independent refrigerant cycles.A kind of multicomponent refrigerant is all used in each circulation, and low level refrigerant cools off and liquefied natural gas with two steps by indirect heat exchange.Heat exchange does not take place with natural gas to be liquefied in high-order refrigerant, but it can cool off low level refrigerant by indirect heat exchange in secondary unit.This heat exchange is carried out with a single step.
United States Patent (USP) 4339253 discloses the method with the mixed cooling medium liquefied natural gas, and in this method, low level refrigerant is with cooling of two steps and liquefied natural gas.High-order refrigerant then cools off this low level refrigerant with a single step.Before the natural gas with drying was added to main liquify area, this high position refrigerant only was used for when initial cooled natural gas till the temperature that reaches the moisture of removing natural gas.If refrigerant is made up of the refrigerant of blending constituent, between each circulation of the liquefaction process of mixing circulation refrigeration, adopt this independent step to carry out heat exchange, got rid of because the regular variation of refrigerant composition and the possibility of closely adaptive heat exchange is provided between each circulation.
In the document, Paradowski is arranged, H and Squera, the article that is entitled as " liquefaction of association gas " that O delivers in the 7th international conference (-19 days Mays 15 of nineteen eighty-three hold) of liquefied natural gas comes liquid gas with the refrigerant cycles of two closures among the liquefaction flow path figure shown in Figure 3 of this article.High-order refrigerant cycles drawn in the flow chart on the right not only is used for cooling off the moisture of original air-flow, and is used to cool off the low level circulation.Compress high-order refrigerant once more with multistep method, and under the temperature and pressure of three kinds of completely different degree, cool off low level refrigerant.The variation of high-order refrigerant composition does not then take in various refrigeration steps in the adaptive heat exchanger.
An object of the present invention is to provide a kind of method that adopts unique natural gas liquefaction flow process, this liquefaction process adopts two kinds of blending ingredients refrigerant in closed circulation, wherein this refrigerant carries out the multistep indirect heat exchange between mutually, comprise the composition that changes refrigerant, wherein lighter component is used for carrying out than low level refrigeration task.
Another object of the present invention provides a kind of equipment of realizing method of the present invention, and this method adopts and adopt two kinds of blending ingredients refrigerant in closed circulation, is used for the liquefaction of natural gas.
The present invention is a kind of method that is used for liquefied natural gas, this method adopts two kinds of closed circulation multicomponent refrigerants, wherein, high-order refrigerant cooling low level refrigerant, cooling of low level refrigerant and liquefied natural gas, this method comprises the following steps: in first closed refrigerant cycles, by heat exchange, with cooling of low level multicomponent refrigerant and liquefied natural gas stream, this refrigerant is heated in described heat exchanging process, this low level refrigerant that has heated is compressed to high pressure and makes its cooling with a kind of external refrigeration fluid, then in second closed refrigerant circulation, cool off described low level refrigerant by the multistep heat exchange with a kind of high-order multicomponent refrigerant, in this heat exchanging process, high-order refrigerant is heated, this high-order refrigerant that has heated is compressed to high pressure and makes its cooling with a kind of external refrigeration fluid, with the described refrigerant that partly liquefies, by being separated, make described high-order refrigerant be divided into gas phase cryogen flow and liquid phase cryogen flow, the part that makes the liquid phase cryogen flow is through the multistep sub-cooled and be expanded to lower temperature and pressure, with cooling low level refrigerant, and cooling and liquefaction gas phase cryogen flow, make the gas phase cryogen flow that has liquefied be expanded to lower temperature and pressure, low level refrigerant is provided the cooling of minimum level.The gas phase cryogen flow of heating is once more mixed with the liquid phase cryogen flow that reaches minimum temperature, and the cryogen flow of this mixing provides a kind of medium cooling degree of low level refrigerant.Then, this high-order cryogen flow of heating once more is recycled, and is used for compressing under various pressure states.
The invention still further relates to two kinds of a kind of equipment that closed circulation multicomponent refrigerant liquefied natural gas is used, in this equipment, high-order refrigerant cooling low level refrigerant, cooling of low level refrigerant and liquefied natural gas, this equipment comprises: a heat exchanger, in order to cool off with low level refrigerant and liquefied natural gas; At least one compressor is used to make low level refrigerant to be compressed to high pressure; An auxiliary heat exchanger is used so that high-order refrigerant cools off low level refrigerant with multistep; A phase separator is used to make low level refrigerant to be divided into gas phase cryogen flow and liquid phase cryogen flow; The device that respectively gas phase cryogen flow and liquid phase cryogen flow is transported to described heat exchanger and described identical gas phase cryogen flow and liquid phase cryogen flow are recycled to described compressors; The compressor that at least one is additional is with so that high-order refrigerant is compressed to high pressure; A heat exchanger, in order to cool off the high-order refrigerant that has compressed with a kind of external refrigeration fluid, a phase separator is in order to be divided into high-order refrigerant gas phase cryogen flow and liquid phase cryogen flow; Carry above-mentioned high-order gas phase cryogen flow by described secondary unit and this vapor phase stream is expanded so that the used device of cooling low level cryogen flow; Above-mentioned high-order liquid phase cryogen flow is carried by the used device of described secondary unit, and this device comprises that separation makes them one by one be expanded to lower temperature and pressure to cool off the used device of described low level refrigerant from the part of the described liquid phase stream of this device then; And make high-order refrigerant by circulating to compress used device once more.
The most handy liquid phase stream is initially cooled off the vapor phase stream of high-order refrigerant, is separated then to be divided into lightweight vapor phase stream and light liquid phase stream, then makes cooling of lightweight vapor phase stream and expansion to be provided for cooling off the minimum cooling degree of low level refrigerant; And light liquid phase stream mixed with the liquid phase stream of telling from first phase separator in high-order refrigerant cycle.
On the other hand, further being separated of vapor phase stream of carrying out between the vapor phase stream of the liquid phase stream of high-order refrigerant and high-order refrigerant after a plurality of multistep heat exchanges are carried out partial liquefaction with liquid phase refrigerant later again.
Accompanying drawing is the schematic flow sheet of optimum operation mode of the present invention.
With reference to accompanying drawing the present invention is described in detail, and most preferred embodiment of the present invention is provided.Original natural gas flow is introduced in the flow process of the present invention by pipeline 10.Natural gas generally contains following ingredients:
C
191.69%
C
2 4.56%
C
32.05%
C
40.98%
C
5+0.41%
N
2 0.31%
This gas raw material that adds is about 33.89 ℃, and pressure is 460.92 * 10
3(kilogram/square metre absolute value) before the liquefaction, must remove most of hydrocarbon heavier than methane from feed stream; And, also must from feed stream, remove remaining moisture.These pre-treatment step do not belong to scope of the present invention, and be general pretreatment process, be well known in the prior art, therefore no longer relating to pretreatment process in this manual, is the low level in pipeline 100 (low temperature) refrigerant heat exchange and cool off just enough in heat exchanger 12 as long as say gas raw material stream in the pipeline 10 at first.Now the natural gas through precooling in the pipeline 14 goes in ring by dry and distilling apparatus to remove moisture and higher hydrocarbon, and this is general cleaning step, does not show in the drawings, just points out to carry out matting in workshop section 16 before liquefaction usually.
The natural gas that the content that making does not have moisture and higher hydrocarbon has significantly reduced is added in the main heat exchanger 20 by pipeline 18, and this heat exchanger preferably is made of the two-stage coil pipe heat exchanger.In the pipeline 22 of first group of main heat exchanger 20 or the first order, this natural gas is cooled and is become liquid by total condensation.The liquefied gas temperature that flows out from first order main heat exchanger 20 is about-133.33 ℃.Make the decompression of this liquefied natural gas by valve 24, carry out sub-cooled then in second group of main heat exchanger 20 or second level pipeline 26, the temperature of the liquefied gas that flows out from this interchanger pipeline 28 time is about-153.89 ℃.Make this liquefied natural gas decompression and in phase separator 32, carry out flash distillation by valve 30.The liquid phase of natural gas is discharged from pipeline 34 as bottom liquid stream, utilizes pump 36 to deliver to the basin of liquefied natural gas (LNG) then.Can from gas tank, extract liquefied natural gas product through pipeline 40.Discharge and in compressor 44, compress once more through pipeline 42 from the steam of liquefied natural gas basin 38, this steam is mixed with the natural gas phase of gas phase by pipeline 46 discharges from phase separator 32.Mixed airflow in the pipeline 48 is heated once more in flash distillation gas recovery heat exchanger 50 and is discharged by pipeline 52, with as fuel gas, is preferably used in the equipment of operation liquefaction factory.
In fact cooling, liquefaction and the sub-cooled that is used for carrying out natural gas is used low level multicomponent refrigerant, and this low level multicomponent refrigerant is made up of nitrogen, methane, ethane, propane and butane usually.In this refrigerant, also can contain ethene and propylene.The accurate concentration of each component in low level refrigerant depends on environmental condition, the composition of gas material, the particularly temperature of used external refrigeration fluid in liquefying plant.The accurate composition of each component of low level refrigerant and concentration range depend on that also desired accurate energy shifts or energy balance between low level refrigerant cycles and the high-order refrigerant cycles.
Making low level refrigerant carry out multistep by compressor 54,56 and 58 compresses suddenly.The heat of compression also can will be passed through with external refrigeration fluid-cooled heat exchanger 55,57 and 59 from the flow of refrigerant of various compression steps, and is removed.The external refrigeration fluid is the water in the environmental condition preferably.Usually, the factory of the liquefied natural gas in close harbour, it is optimal liquefying as cooling water with seawater on every side.
With temperature is 37.78 ℃, and pressure is 351.85 * 10
3Kilogram/square metre (absolute value) mainly contains methane and ethane, and the low level refrigerant that also contains small amounts of propane and nitrogen is sent into the first order of level Four secondary unit.This heat exchanger has makes low level refrigerant carry out the used device of heat exchange to high-order refrigerant.So-called high-order refrigerant represent this refrigerant in refrigeration processes temperature than low level refrigerant height.Low level refrigerant in the pipeline 60 reduces by first order heat exchanger 62 back temperature, but its temperature still is higher than liquefaction point.This cryogen flow continues by secondary unit level 64 and by partial liquefaction, and low level refrigerant passes through the further cooling of level 66 and 68 backs of heat exchanger, but still is not liquefied fully.Each grade secondary unit provides a cooling than low level, makes heat exchanger 62 than the temperature height of heat exchanger 68, and heat exchanger 68 is temperature promptly the coldest minimum points in this secondary unit.Then the two-phase low level refrigerant in the pipeline 70 is sent into phase separator 72.The liquid phase of low level refrigerant is discharged by pipeline 74 as bottom liquid stream.This cryogen flow is sent into first group of pipeline 76 of main heat exchanger 20.Make liquid phase low level refrigerant sub-cooled and discharge, carry out step-down and cooling by valve 78.Then, this refrigerant is sent into the tube space of coiled pipe main heat exchanger as the refrigerant that sprays downwards, with by the various cryogen flow of indirect heat exchange cooling in the first order or first group of main heat exchanger by pipeline 80.
Vapor phase stream from separator 72 is discharged by pipeline 82 as a kind of upper strata cryogen flow.A large amount of gas phase low level refrigerant is directly by pipeline 84, liquefies in main heat exchanger 20 first group or the first order pipeline 86.Refrigerant in the pipeline 86 in second group of main heat exchanger 20 or second level pipeline 88 by sub-cooled.Lowered the temperature and step-down by valve 90 through cold liquid cryogen.Discharge by 94 from the gas phase cryogen flow that phase separator 72 is escaped, be stored in the heat exchanger 50 refrigeration value from the flash distillation gas of liquefied natural gas in order to recovery.The cryogen flow of this escape is lowered the temperature and step-down in valve 96, and mixes mutually with remaining the original gas phase refrigerant part in the pipeline 92.Mixed cooling medium stream in the pipeline 98 is sent into the top of main heat exchanger 20, and earlier at second assembly forming by pipeline 26 and 88, then first injection refrigerant above assembly of forming by pipeline 22,86 and 76.Second assembly that forms low level refrigeration provided by heat exchanger 20.This low pressure and the low level refrigerant through heating once more carry out heat exchange in main heat exchanger 20 after, discharge through pipeline 100 from the bottom of heat exchanger 20.This low level refrigerant makes the natural gas that is added in the heat exchanger 12 reach preliminary cooling, is recycled in order to compression once more by pipeline 102 then.
The high-order refrigerant that its used refrigeration task temperature is much higher than low level refrigerant has constituted second system of two closed-circuit refrigeration systems of the present invention.This high position refrigerant preferably only is used to cool off low level refrigerant by indirect heat exchange.This high position refrigerant can also be used for cooling off natural gas to be liquefied, as the cooling curve of this natural gas in interchanger 12 near various cryogen flow.High-order refrigerant contains following ingredients usually:
C
228.79%＊
C
367.35%＊
C
43.86%
* in addition, in refrigerant, also can use ethene and propylene.
Can under various pressure high-order refrigerant be sent into compound compressor 104, behind middle selectivity cooling step, the high-order refrigerant in the gas phase is discharged through pipeline 106, and its temperature is 76.67 ℃, and pressure is about 246.29 * 10
3Kilogram/square metre (absolute value).This refrigerant is cooled off once more by the external refrigeration fluid in heat exchanger 108.This external refrigeration fluid can be the water such as at ambient temperature.Make this high position refrigerant partial condensation with the external refrigeration fluid, the refrigerant of the pipeline 110 of flowing through of discharging from heat exchanger is gas phase and liquid phase mixture.The gas phase of high-order refrigerant is separated in phase separator 112 with liquid phase.Gas phase is discharged through pipeline 114 from the top of phase separator 112.
Then, make the vapor phase stream of high-order refrigerant pass through secondary unit, particularly 62,64,66 and 68 grades, so that cooling and this vapor phase stream that liquefies.Then, the vapor phase stream that has liquefied is expanded to lower temperature and pressure by valve 116.At this moment, temperature is about-48.33 ℃ two-phase refrigerant with the coldest level or the low temperature level 68 of convection type by secondary unit, so that low level refrigerant in the pipeline 70 and the gas phase cryogen flow in the pipeline 114 have minimum refrigeration degree.This two-phase refrigerant of being discharged by the last level 68 of secondary unit is with the two-phase cryogen flow pipeline 118 of flowing through, and its temperature is about-34.44 ℃.
Discharge by pipeline 120 as the bottom cryogen flow from the high-order refrigerant of the liquid phase of phase separator 112.This liquid phase stream is by first order secondary unit 62 and carry out sub-cooled earlier, discharges one tributary of liquid phase cryogen flow then, and this one tributary is expanded to lower temperature and pressure in valve 122.This moment, this refrigerant tributary was a two-phase, and cooling effect with the convection type first order secondary unit 62 of flowing through, is played in this liquid phase tributary in the pipeline 124 in this grade heat exchanger.Refrigerant through heating once more is recycled the compressor of getting back under moderate pressure 104 through pipeline 125, in order to compression once more.
Make the residue cryogen flow of initially passing through cold liquid phase cryogen flow in the pipeline 126 further cold excessively in second level secondary unit 64, and discharge second burst of tributary, expand by valve 128 in this burst tributary, with cooling and step-down.With in the pipeline 130 now for two-phase refrigerant with the mode of the convection current second level secondary unit 64 of flowing through, so that in this grade heat exchanger, carry out the cooling task.Refrigerant through heating once more is recycled the compressor of getting back under moderate pressure 104 through pipeline 131, and in order to compression once more, the pressure of the above-mentioned backflow 125 of the pressure ratio of cryogen flow is low in the pipeline 131.Second burst of remaining liquid phase cryogen flow in pipeline 132 passed through third level secondary unit 66 earlier by sub-cooled, and all then cryogen flow are expanded to lower temperature and pressure by valve 130, and mix with the vapor phase stream in the pipeline 118.Mixed cooling medium stream in pipeline 136, is carried out in this grade heat exchanger to cool off or the refrigeration task so that be by third level secondary unit 66 with convection type.In the cryogen flow of all circulations, its pressure of the refrigerant in the pipeline 138 is minimum, and the compressor 104 that this refrigerant is recycled get back under lowermost level pressure is in order to compression once more.
Freezing capacity improved when the flow chart of high-order refrigerant can make high-order refrigerant cool off low level refrigerant.Used cascade system in the heat exchange circulation, returns the light components of refrigerant usually in the prior art, compressing once more, and continues the separation of heavy component, in order between multiple fluid, carries out refrigeration in the low temperature heat exchange of many heat exchanges.The present invention carries out initial being separated in separator 112, the light components guiding that makes high-order refrigerant then earlier is by heat and moderate heat exchange level, make light components be expanded to lower temperature and pressure again, to be used for the secondary unit of low temperature level.This light components in 68 grades of heat exchangers, provides the good refrigerant as low level or cryogenic cooling task because boiling temperature is minimum.
In addition, the liquid phase height cryogen flow of discharging after being separated in the self-separation device 112 is not to be divided into many tributaries by being separated resembling in the prior art, and just the part in all liquid streams once is separated and is divided into many tributaries.This non-being separated can prevent to be used for the heavy component gathering that the refrigerant of cooling task is carried out in all colder level heat exchanges.The present invention makes the liquid phase cryogen flow of having separated expand after separate in each tributary, and therefore, expansion itself just has cooling effect, and lightweight refrigerant component can not separated from heavy refrigerant component.By cooling process figure of the present invention, can obtain the adaptability refrigerant component that is applicable to that having of secondary units at different levels is good, in secondary unit, thermal level is 62, middle grade be 64 and colder level be 66, all add identical cryogen flow, be not lowered and do not resemble the temperature of only in relevant heat exchanger, carrying out the cryogen flow that contains heavy component of refrigeration task the prior art.
In addition, in colder middle grade secondary unit 66, the gas phase refrigerant in the pipeline 118 mixes mutually with the liquid phase cryogen flow in the pipeline 132, so that better mixing and high concentration lightweight refrigerant component to be provided.This total refrigerant flow process can improve freezing capacity and make high-order refrigerant and low level refrigerant between the refrigeration task result of thermodynamics suitability is preferably arranged.
Preferably utilize extra level as secondary unit 140, vapor phase stream 114 is initially cooled off, in separator 144, be separated then, make and discharge through pipeline 146 in the upper strata even lighter mixed cooling medium component, send in the level 68, be used for carrying out last refrigeration task at the secondary unit of this coldest level.The liquid phase stream that generates by being separated in 144 is discharged through pipeline 148, and then sends in the liquid phase cryogen flow 120.Make additional heavy component forward liquid phase stream to, to provide additional thermodynamics suitability to refrigeration tasks at different levels from vapor phase stream.On the other hand, cryogen flow 148 can be passed through level 62,64 and 66, and mixes with cryogen flow 118 separately, thereby further the separation of lighter component is to be used for carrying out last refrigeration task.
Secondly, after the at different levels of secondary unit as 62,64 and 66 coolings, make cryogen flow condensation of part gas phase and separation of lighter refrigerant component to carry out the refrigeration task of lower temperature with phase disengagement method, this process can be carried out repeatedly.
In liquefying plant, adopt binary to mix refrigerant cycles, can make the variation free degree of refrigerant component in each circulation big, so that can shift from high-order refrigerant or low level refrigerant to the compression energy load of refrigerant, this situation depends on the possibility of carrying out the refrigeration task with extraneous cooling fluid, in refrigeration processes, after compressing once more, need to cool off once more for making high-order refrigerant and low level refrigerant with this external world's cooling fluid.In the present invention, liquefy with two kinds of blending ingredients refrigerant, its advantage is: have high freezing capacity.
Though the configuration of auxiliary exchanger shows in the accompanying drawing, minimum at its extreme higher position refrigeration degree, can imagine a kind of auxiliary exchanger, its configuration is with above-mentioned opposite, and is promptly minimum at lowest part refrigeration degree, and cryogen flow flows through interchangers at different levels in an identical manner.
Also can imagine: in interchanger 12, make natural gas flow refrigeration, in this interchanger, not only carry out refrigeration, and should have the tributary of high-order refrigerant to participate in refrigeration with low level refrigerant.On the contrary, the tributary of natural gas should be discharged from feeding tube 10, and makes its cooling with high-order refrigerant, turns back to then in the interchanger 12, and these embodiments no longer are illustrated.
Abovely the present invention has been done detailed description, still,, can in this patent scope, carry out various changes this programme for those skilled in the art according to optimum implementation.The scope of this patent should be determined by following claim.
Claims (32)
1, a kind of method of utilizing two kinds of mixed cooling medium liquefied natural gas, wherein high-order refrigerant is used for cooling off low level refrigerant, and this low level refrigerant is used for cooling off and liquefied natural gas, this method comprises the following steps:
A, in first closed refrigerant circulation, by carrying out heat exchange cooling and liquefied natural gas stream with the low level multicomponent refrigerant, refrigerant is heated once more in this heat exchanging process;
B, described low level refrigerant to one elevated pressure that has heated of compression, and it is cooled off once more with a kind of external refrigeration liquid;
C, in the circulation of second closed refrigerant, by, multistep indirect and the different heat exchange of each section pressure, further cool off described low level refrigerant with high-order multicomponent refrigerant, in described heat exchanging process, this high position refrigerant is heated; Make the above-mentioned high-order refrigerant that has heated be compressed to an elevated pressure, and it is cooled off once more, so that this refrigerant partly liquefies with a kind of external refrigeration fluid from its multistage pressure drop point;
D, by being separated, make this high position refrigerant be divided into gas phase cryogen flow and liquid phase cryogen flow, so that available lighter refrigerant component is finished the task of the most low cooling among the cooling step c;
Thereby e, the high-order cryogen flow that makes Partial Liquid Phase are crossed cold-peace through multistep and are expanded to low level refrigerant among the lower temperature and pressure cooling step c and the gas phase cryogen flow among cooling and the liquefaction step d;
F, make the gas phase refrigerant cooling of having liquefied, be expanded to lower temperature and pressure then,, low level refrigerant is provided the cooling of minimum cooling degree with the lightest component with high-order refrigerant.
2, in accordance with the method for claim 1, it is characterized in that, the high-order cryogen flow of gas phase is cooled off with the high-order cryogen flow of liquid phase at first, be divided into lightweight vapor phase stream and light liquid phase stream then through being separated, make lightweight vapor phase stream further cooling and expansion, so that low level refrigerant reaches minimum cooling degree, the light liquid phase that obtains being separated stream mixes with the liquid phase cryogen flow.
3, in accordance with the method for claim 2, it is characterized in that, make the high-order cryogen flow of gas phase carry out the multistep cooling, be separated and further cooling.
4, in accordance with the method for claim 1, it is characterized in that, low level refrigerant is separated, its liquid phase is in order to preliminary cooled natural gas, and gas phase is divided into two bursts of tributaries again, main air is by liquid phase cools, and the flash gas of the liquefied natural gas that secondary air flow is generated cools off, and this main air and secondary air flow mix to carry out last cooling and liquefied natural gas then.
5, in accordance with the method for claim 1, it is characterized in that the compression of low level refrigerant is carried out in multistep.
6, in accordance with the method for claim 1, it is characterized in that contracting of high-order refrigerant carried out in multistep.
7, in accordance with the method for claim 1, it is characterized in that the external refrigeration fluid is the water in the external condition.
8, in accordance with the method for claim 7, it is characterized in that the temperature of water is lower than 18.33 ℃.
9, in accordance with the method for claim 1, it is characterized in that multicomponent refrigerant is grouped into by two or more one-tenth, these compositions are selected from following compounds: methane, ethane, ethene, propane, butane, pentane and nitrogen.
10, a kind of equipment of realizing the described method of claim 1, this complete equipment comprises:
A) heat exchanger is used to make low level refrigerant cooling and liquefied natural gas;
B) at least one compressor is so that described low level refrigerant is compressed to an elevated pressure;
C) auxiliary heat exchanger is used for cooling off low level refrigerant indirectly with high-order refrigerant;
D) phase separator is used to make low level refrigerant to be divided into vapor phase stream and liquid phase stream;
E) be used for vapor phase stream and liquid phase stream are transported to the described heat exchanger of feature (a) respectively, and with its defeated device of getting back to the described compressor of feature (b);
F) at least one compressor is used to make high-order refrigerant to be compressed to an elevated pressure;
G) heat exchanger is used for but this high-order refrigerant that has compressed of a kind of external refrigeration liquid cooling;
H) phase separator is used to make high-order refrigerant to be divided into vapor phase stream and liquid phase stream;
I) be used to make high-order refrigerant and low level refrigerant to carry out heat exchange and make the device of high-order refrigerant cycle to compress once more,
It is characterized in that,
J) above-mentioned secondary unit is a heat exchanger with medium temperature level and minimum temperature level, high-order refrigerant pressure difference at different levels; In addition, this equipment also comprises:
K) be used for carrying described high-order vapor phase stream by described secondary unit and described vapor phase stream being expanded so that provide the device of minimum cooling class to the low level cryogen flow, and
L) be used for described high-order liquid phase stream is sent into the device of described secondary unit, comprise that a part that is used for described liquid phase stream separates, make it one by one be expanded to different lower temperature and pressures then to cool off the multilevel device of this low level refrigerant.
11, according to the described equipment of claim 10, it is characterized in that, comprise a phase separator, use so that the high-order vapor phase stream of cooling off with the high-order cryogen flow of liquid phase at first in the feature (h) is divided into lightweight vapor phase stream and light liquid phase stream.
12, according to the described equipment of claim 10, it is characterized in that compressor has multistage.
13, according to the described equipment of claim 11, it is characterized in that, comprise a plurality of phase separators, use so that the initial high-order gas phase refrigerant with the high-order cryogen flow cooling of liquid phase in the feature (h) is divided into lightweight vapor phase stream and light liquid phase stream.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN85101713.4A CN1004228B (en) | 1985-04-01 | 1985-04-01 | To liquidize natural gas by two mixed refrigerants |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN85101713.4A CN1004228B (en) | 1985-04-01 | 1985-04-01 | To liquidize natural gas by two mixed refrigerants |
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| Publication Number | Publication Date |
|---|---|
| CN85101713A CN85101713A (en) | 1987-01-31 |
| CN1004228B true CN1004228B (en) | 1989-05-17 |
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ID=4792010
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN85101713.4A Expired CN1004228B (en) | 1985-04-01 | 1985-04-01 | To liquidize natural gas by two mixed refrigerants |
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| CN (1) | CN1004228B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102445052A (en) * | 2011-12-16 | 2012-05-09 | 南京林业大学 | Biogas liquefaction process and device for scattered gas source point |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008509374A (en) * | 2004-08-06 | 2008-03-27 | ビーピー・コーポレーション・ノース・アメリカ・インコーポレーテッド | Natural gas liquefaction method |
| US20110146342A1 (en) * | 2008-08-06 | 2011-06-23 | Lummus Technology Inc. | Method of cooling using extended binary refrigeration system |
| DE102009018248A1 (en) * | 2009-04-21 | 2010-10-28 | Linde Aktiengesellschaft | Process for liquefying a hydrocarbon-rich fraction |
| CA3140415A1 (en) * | 2013-03-15 | 2014-09-18 | Chart Energy & Chemicals, Inc. | Mixed refrigerant system and method |
| US9696086B2 (en) | 2014-01-28 | 2017-07-04 | Dresser-Rand Company | System and method for the production of liquefied natural gas |
| US9920987B2 (en) * | 2015-05-08 | 2018-03-20 | Air Products And Chemicals, Inc. | Mixing column for single mixed refrigerant (SMR) process |
| DE102015009255A1 (en) * | 2015-07-16 | 2017-01-19 | Linde Aktiengesellschaft | Method for cooling a process stream |
| US10619917B2 (en) * | 2017-09-13 | 2020-04-14 | Air Products And Chemicals, Inc. | Multi-product liquefaction method and system |
| GB2581135A (en) * | 2019-01-30 | 2020-08-12 | Linde Ag | Cooling method for liquefying a feed gas |
-
1985
- 1985-04-01 CN CN85101713.4A patent/CN1004228B/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102445052A (en) * | 2011-12-16 | 2012-05-09 | 南京林业大学 | Biogas liquefaction process and device for scattered gas source point |
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| Publication number | Publication date |
|---|---|
| CN85101713A (en) | 1987-01-31 |
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