WO2014114264A1 - 一种天然气等压液化装置 - Google Patents

一种天然气等压液化装置 Download PDF

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Publication number
WO2014114264A1
WO2014114264A1 PCT/CN2014/071402 CN2014071402W WO2014114264A1 WO 2014114264 A1 WO2014114264 A1 WO 2014114264A1 CN 2014071402 W CN2014071402 W CN 2014071402W WO 2014114264 A1 WO2014114264 A1 WO 2014114264A1
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refrigerant
natural gas
liquefaction
methane
liquid
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PCT/CN2014/071402
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English (en)
French (fr)
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王海波
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南京瑞柯徕姆环保科技有限公司
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Priority to US14/763,760 priority Critical patent/US9879905B2/en
Publication of WO2014114264A1 publication Critical patent/WO2014114264A1/zh

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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
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/0204—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the feed stream
    • F25J3/0209—Natural gas or substitute natural gas
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/0228—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream
    • F25J3/0233—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream separation of CnHm with 1 carbon atom or more
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/0228—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream
    • F25J3/0257—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream separation of nitrogen
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2200/00—Processes or apparatus using separation by rectification
    • F25J2200/04—Processes or apparatus using separation by rectification in a dual pressure main column system
    • F25J2200/06—Processes or apparatus using separation by rectification in a dual pressure main column system in a classical double column flow-sheet, i.e. with thermal coupling by a main reboiler-condenser in the bottom of low pressure respectively top of high pressure column
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2200/00—Processes or apparatus using separation by rectification
    • F25J2200/20—Processes or apparatus using separation by rectification in an elevated pressure multiple column system wherein the lowest pressure column is at a pressure well above the minimum pressure needed to overcome pressure drop to reject the products to atmosphere
    • 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
    • F25J2205/00—Processes or apparatus using other separation and/or other processing means
    • F25J2205/02—Processes or apparatus using other separation and/or other processing means using simple phase separation in a vessel or drum
    • F25J2205/04—Processes or apparatus using other separation and/or other processing means using simple phase separation in a vessel or drum in the feed line, i.e. upstream of the fractionation step
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2210/00—Processes characterised by the type or other details of the feed stream
    • F25J2210/42—Nitrogen
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2215/00—Processes characterised by the type or other details of the product stream
    • F25J2215/04—Recovery of liquid products
    • 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
    • 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
    • F25J2235/00—Processes or apparatus involving steps for increasing the pressure or for conveying of liquid process streams
    • F25J2235/42—Processes or apparatus involving steps for increasing the pressure or for conveying of liquid process streams the fluid being nitrogen
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2240/00—Processes or apparatus involving steps for expanding of process streams
    • F25J2240/02—Expansion of a process fluid in a work-extracting turbine (i.e. isentropic expansion), e.g. of the feed stream
    • F25J2240/12—Expansion of a process fluid in a work-extracting turbine (i.e. isentropic expansion), e.g. of the feed stream the fluid being nitrogen
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2240/00—Processes or apparatus involving steps for expanding of process streams
    • F25J2240/90—Hot gas waste turbine of an indirect heated gas for power generation
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2270/00—Refrigeration techniques used
    • F25J2270/90—External refrigeration, e.g. conventional closed-loop mechanical refrigeration unit using Freon or NH3, unspecified external refrigeration
    • F25J2270/904—External refrigeration, e.g. conventional closed-loop mechanical refrigeration unit using Freon or NH3, unspecified external refrigeration by liquid or gaseous cryogen in an open loop

Definitions

  • Natural gas isostatic liquefaction device Natural gas isostatic liquefaction device
  • the invention relates to a natural gas isobaric liquefaction device, which belongs to the technical field of deep freezing.
  • Natural gas is a high-quality and clean fossil energy source and plays an important role in the national economy.
  • the liquefaction and storage of natural gas is a key technology for its development and utilization. It has formed an industry at home and abroad, growing at an average rate of 8% per year. In recent years, China's energy consumption structure has grown rapidly. LNG technology has become a high-tech technology and has received more and more attention from science and technology disciplines.
  • Cascade liquefaction process also called cascade liquefaction process, cascade liquefaction process or tandem evaporation condensate liquefaction process, mainly used in basic load natural gas liquefaction plant;
  • mixed refrigerant liquefaction process the so-called MRC liquefaction process
  • MRC is C1 to C5 hydrocarbons, and N 2 and other five-component multi-component mixed refrigerant as the working medium, for stepwise condensation, evaporation Throttle expansion to obtain cooling capacity at different temperature levels, in order to achieve the purpose of gradual cooling and liquefied natural gas.
  • MRC not only achieves the purpose of a similar cascade liquefaction process, but also overcomes the shortcomings of its complex system. Since the 1980s, for the basic load natural gas liquefaction plant, the newly built and expanded basic load natural gas liquefaction process has almost exclusively adopted the propane pre-cooling mixed refrigerant liquefaction process;
  • Liquefaction process with expander refers to the process of liquefying natural gas by using the Claude cycle in the refrigerant re-turbine expander.
  • the gas expands and works in the expander while reducing the temperature and recovering work. According to the different refrigerants, it can be divided into a nitrogen expansion liquefaction process and a natural gas expansion liquefaction process.
  • the advantages of this type of process are: (1) The process is simple, flexible, reliable, easy to start, easy to operate, and easy to maintain; (2) When using natural gas as a working medium, it can save special production, transportation, storage and transportation. The cost of the agent.
  • the disadvantages are: (1) feeding The airflow of the device needs to be fully dried; (2) The return pressure is low, the heat exchange area is large, and the equipment metal input is large; (3) It is limited by the number of low-pressure users; (4) The liquefaction rate is low, such as recycling, it is increasing. After the recycle compressor, the power consumption is greatly increased. Because the liquefaction process with expander is relatively simple and the investment is moderate, it is especially suitable for peaking natural gas liquefaction equipment with less liquefaction ability.
  • Figure 1 is a schematic diagram of a cascading natural gas liquefaction process.
  • Figure 2 is a schematic diagram of the liquefaction process of the APCI propane precooled mixed refrigerant.
  • Figure 3 is the natural gas expansion liquefaction process
  • Figure 3 1- dehydrating agent, 2-carbon dioxide removal tower, 3-water cooler, 4-return gas compressor, 5, 6, 7-heat exchanger, 8-over Cooler, 9-storage tank, 10-expander, 11-compressor.
  • Figure 4 is a nitrogen expansion liquefaction process
  • Figure 4 1-Pretreatment unit, 2, 4, 5-heat exchanger, 3-heavy hydrocarbon separator, 6-nitrogen stripper, 7-turboexpander, 8 - Nitrogen-methane separation column, 9-cycle compressor.
  • Figure 5 is a schematic diagram of the natural gas expansion liquefaction process with propane pre-cooling
  • Figure 5 1, 3, 5, 6, 7 - heat exchanger, 2, 4-propane heat exchanger, 8-water cooler, 9- Compressor, 10-Brake Compressor, 12, 13, 14-Gas-Liquid Division
  • the indicator is the coefficient of refrigeration, which is the ratio of the benefits received and the cost of the cost, and is measured by the atmospheric temperature. With all refrigeration cycles between the temperature and the low temperature heat source (such as cold storage), the cooling coefficient of the reverse Carnot cycle is the highest:
  • the temperature of the high temperature heat source in formula (2) is 7; and the temperature of the low temperature heat source is ⁇ 2 is higher than the atmospheric temperature ⁇ . And can draw the following important conclusions: 1) The thermal efficiency of the Carnot cycle is determined only by the temperature of the high-temperature heat source and the low-temperature heat source, that is, the temperature at which the working medium absorbs heat and exotherms. Increasing the temperature of 7 and ⁇ 2 can improve the thermal efficiency.
  • the Carnot cycle and its thermal efficiency formula are of great significance in the development of thermodynamics.
  • the study of the Carnot cycle points out the direction for improving the thermal efficiency of various thermodynamic machines. It is possible to increase the endothermic temperature of the working medium and reduce the exothermic temperature of the working medium as much as possible. , the exotherm is carried out near the lowest temperature that can be naturally obtained, that is, the atmospheric temperature.
  • the method of utilizing adiabatic compression to increase the heat absorption temperature of the gas proposed in the Carnot cycle has hitherto been widely used in gas-based thermodynamic machines.
  • the limit of the Carnot cycle is the atmospheric ambient temperature. For the refrigeration process cycle below ambient temperature, the Carnot cycle does not give a definitive answer.
  • thermodynamics cannot make a simple, clear and intuitive explanation of the natural gas liquefaction cycle.
  • the power consumption and utility consumption per ton of LNG is about 850 degrees, and the energy consumption of the process is extremely large.
  • the purpose of the invention is to solve the imperfection of the theoretical analysis of the circulation of the natural gas liquefaction device by the Carnot's theorem, and propose a new refrigeration theory corresponding to the thermodynamic theory, namely the cold mechanics theory, and propose a new natural gas isobaric pressure designed by the principle.
  • the liquefaction device overcomes the shortcomings of the traditional natural gas liquefaction process, high energy consumption, and must be equipped with excess public facilities such as circulating cooling water system, retaining and carrying forward the advantages of the liquefaction process with expander, and greatly reducing it.
  • the energy consumption is more than 30%.
  • the isobaric condensation of natural gas is realized, and the equipment maintenance and material spare capacity are greatly reduced, thereby realizing the transformation of natural gas liquefaction technology.
  • the refrigeration device refers to the consumption of mechanical work to achieve the transfer of cold energy from an atmospheric environment to a low temperature cold source or from a low temperature cold source to a lower temperature cold source.
  • refrigerants some substances are required as working substances of the refrigeration device, which are called refrigerants.
  • the second law of cold mechanics is proposed: the essence of the second law of cold mechanics is the same as the essence of the second law of thermodynamics, and also follows the principle of energy decay. That is, different forms of cold energy have a "quality" difference in the ability to convert the amount of success; even if the same form of cold energy has different states of existence, its conversion ability is different.
  • the actual process of all cold energy transmission always proceeds in the direction of decline in energy quality, and all cold energy will always spontaneously shift to the atmospheric environment.
  • the process of improving the energy quality of cold energy cannot be carried out automatically and separately.
  • the process of improving energy quality must be accompanied by the simultaneous decline of another energy quality.
  • the process of energy quality decline is to achieve the process of energy quality increase.
  • the necessary compensation conditions that is, at the cost of energy degradation, as compensation to promote the realization of the energy quality rise process.
  • the process of energy degradation as a cost must be sufficient to compensate for the process of rising energy quality to meet the general rule that the total energy quality must fall. Therefore, under certain compensation conditions with reduced energy quality, the process of energy quality increase must have a maximum theoretical limit. This theoretical limit can only be reached under perfectly reversible ideal conditions. At this time, the energy quality rise value is exactly equal to the compensation value of the energy quality drop, so that the total energy quality remains unchanged.
  • Tc2 ⁇ Tcl ⁇ To To is the ambient temperature, which is the Kelvin temperature scale.
  • the maximum cooling efficiency of the cold source under Tcl and Tc2 is: Set to the cooling capacity of the q 2 cycle, w.
  • the cold source temperature is Tel:
  • the ambient temperature To is determined, the lower the cold source temperature, the same work is input from the cold source, and the more cooling capacity is obtained, which indicates the direction for constructing a new natural gas liquefaction plant process.
  • the amount of cooling is spontaneously transmitted from a cold source to an ambient temperature
  • the best type of work to be done outward is the temperature difference generator using the Seebeck effect, that is, the cold power generator;
  • thermodynamics which is in line with the basic principles of scientific aesthetics, that is, the principle of oppositeism and symmetry.
  • the present invention proposes a process organization that is different from the conventional natural gas liquefaction device, and the low-energy consumption achieves the isoelectric liquefaction of the natural gas, and effectively reduces the energy consumption of the natural gas liquefaction device, so that the specific power consumption of the natural gas is reduced to 0.24 kW. h/kg or so.
  • the object of the invention is achieved by the following measures:
  • a natural gas isobaric liquefaction device comprising a natural gas and processing system, a liquefaction system, a supplemental cooling system, a storage system, a control system and a fire protection system, and the present invention only lists the most important components, namely a liquefaction flow diagram, not detailed The contents of the description are matched according to the traditional mature technology, and the process steps for realizing isothermal liquefaction of natural gas are as follows:
  • the replenishing system of the device refers to the liquid refrigerant 20 from the refrigerant storage tank 19, and the refrigerant gas-liquid mixture 22 formed by the cryogenic liquid pump 21 and the regenerator 18 enters the upper tower 10,
  • the condensing evaporator 9 condenses the methane gas of the lower tower to produce liquid methane, and the low temperature refrigerant 15 from the upper tower 10 passes through the cold exchanger 6, and the cold exchanger 3 to cool the raw natural gas 1 to form a superheated steam of the refrigerant.
  • the refrigerant After being expanded and depressurized by the expander 17, the refrigerant is returned to the refrigerant storage tank 19 via the regenerator 21 and the throttle valve 23, and the natural gas liquefaction system is supplemented by the condensing evaporator 9, the cold exchanger 6, and the cold exchanger 3.
  • the required cooling capacity is entered to form a refrigerant circulation loop of the refrigerant; the pressure of the supplemental cooling system can be conveniently adjusted by the throttle valve 23 provided.
  • the brake device 24 of the expander 17 is a fan, a motor, a hydraulic pump or a compressor.
  • the methane in the upper part of the lower tower 8 can also be directly introduced into the upper column 10 to be washed by liquid nitrogen to produce liquid pure methane, from the bottom of the upper tower 10 The portion is taken to the liquid pure methane storage tank 14.
  • the isostatic separation refers to the raw material natural gas entering the natural gas liquefaction system, and does not need to be throttled and depressurized for liquefaction as in the conventional natural gas liquefaction process, and the raw natural gas 1 sent only has resistance loss along the process equipment and pipeline, and Treated as an isobaric liquefaction process.
  • the liquefaction system includes a lower column 8, a condensing evaporator 9, and an upper column 10, and adopts an integrated or split structure.
  • the refrigerant has a boiling point lower than or equal to methane at a standard pressure, including but not limited to a mixed gas of one or more gases such as methane, nitrogen, argon, helium, hydrogen, etc., if safety is ensured, Hydrogen or liquid hydrogen can be used, preferably nitrogen.
  • the refrigerant storage tank 19 adopts necessary heat insulation and cold preservation measures, such as an insulated vacuum storage material such as an adiabatic vacuum container or a pearl sand.
  • the cold exchanger 6, the cold exchanger 3, and the regenerator 18 are of a shell-and-tube type, a plate-fin type, a micro-channel or other type of cooler, and the structure and the cold-change element are in the conventional natural gas liquefaction process.
  • Shell-and-tube heat exchangers, plate-fin heat exchangers, microchannel heat exchangers, etc. are identical, just to replace the exact name for the corresponding refrigeration system.
  • the cold exchanger 3, the cold exchanger 6, the separator 4, and the chiller 18 may be provided one or more.
  • Equipment not described in the present invention and its backup system, piping, instrumentation, valves, cold insulation, bypassing facilities with regulating functions, etc. are matched by well-known technologies of conventional natural gas liquefaction systems.
  • the apparatus of the present invention is equally applicable to the liquefaction of other gases which employ a refrigerant having a boiling point at standard atmospheric pressure lower than or equal to the boiling point of the corresponding liquefied gas at standard atmospheric pressure.
  • LNG or liquid pure methane produced by isostatic condensation can save the electricity consumed by the pressurized process of traditional LNG or pure liquid methane.
  • the natural gas can be liquefied by low pressure, and the method of pressurizing the liquefied natural gas can save the gas compression work of the traditional natural gas liquefaction process, and the utility power consumption of the natural gas liquefaction system is reduced by more than 80%. 4.
  • the process setting is more concise, the potential of the liquefaction system is fully exerted, the operation flexibility is large, and the operation adjustment is more flexible and convenient.
  • Figure 1 is a schematic diagram of a cascading natural gas liquefaction process
  • FIG. 2 is a schematic diagram of a liquefaction process of an APCI propane pre-cooling mixed refrigerant
  • Figure 3 shows the natural gas expansion liquefaction process
  • Figure 3 1- dehydrating agent, 2-carbon dioxide removal tower, 3-water cooler, 4-return gas compressor, 5, 6, 7- heat exchanger, 8-supercooler, 9-storage tank, 10 - Expander, 11-compressor.
  • Figure 4 shows the nitrogen expansion liquefaction process
  • Figure 4 1-Pretreatment unit, 2, 4, 5-heat exchanger, 3-heavy hydrocarbon separator, 6-nitrogen stripper, 7-turboexpander, 8-nitrogen-methane separation tower, 9- Recirculating compressor.
  • Figure 5 is a schematic diagram of the natural gas expansion liquefaction process with propane pre-cooling:
  • Figure 5 1, 3, 5, 6, 7 - heat exchanger, 2, 4-propane heat exchanger, 8-water cooler, 9-compressor, 10-brake compressor, 12, 13, 14 -Gas-liquid separator.
  • FIG. 6 is a schematic flow chart of a natural gas isostatic liquefaction apparatus of the present invention:
  • Figure 6 1-feedstock natural gas, 2-pretreatment unit, 3-cold exchanger, 4-heavy hydrocarbon separator, 5-liquid heavy hydrocarbon component, 6-cold exchanger, 7-precooled into the column feed gas , 8-lower tower, 9-condensation evaporator, 10-upper tower, 11-LNG, 12-LNG storage tank, 13-pure liquid methane, 14-pure liquid methane storage tank, 15-out tower low temperature refrigerant, 16 - refrigerant superheated steam, 17-expander, 18-refrigerator, 19-refrigerant storage tank, 20-liquid refrigerant, 21- cryogenic liquid pump, 22-refrigerant gas-liquid mixture, 23-throttle, 24-braking equipment.
  • a natural gas isobaric liquefaction device the refrigerant is nitrogen, and the specific implementation is as follows:
  • the raw natural gas 1 is removed by the pretreatment device 2 to remove moisture and carbon dioxide, enters the cold exchanger 3, and the heavy hydrocarbon separator 4 separates the liquid heavy hydrocarbon component 5, and then passes through the cold exchanger 6 to be pre-cooled into the column feed gas 7 ;
  • the brake device 24 of the expander 17 employs a compressor for pressurizing the raw natural gas.
  • the refrigerating medium storage tank 19 adopts necessary thermal insulation and cold preservation measures, such as an insulated thermal insulation material such as an adiabatic vacuum container or a pearl sand.
  • Equipment not described in the present invention and its backup system, piping, instrumentation, valves, cold insulation, bypassing facilities with regulating functions, etc. are matched by well-known technologies of conventional natural gas liquefaction systems.

Abstract

一种天然气等压液化装置，包括天然气预处理系统、预冷系统、液化系统、补冷系统、储存系统、控制系统和消防系统。该系统采用低温液体泵输入功，通过制冷工质对天然气液化装置进行补冷，从而实现天然气的等压液化。

Description

一种天然气等压液化装置 技术领域
本发明涉及一种天然气等压液化装置， 具体属深度冷冻技术领域。
背景技术
天然气是一种优质洁净的化石能源，在国民经济中具有十分重要的地位。 天然气的 液化和储存是其开发利用的关键技术，在国内外已形成一个产业， 每年以平均 8%的速度 增长， 近年来在中国能源消费结构中， 增长很快。 液化天然气技术已经成为一门高科技 技术， 受到越来越多科学技术学科的重视。
预计到本世纪中叶，若以中国消耗天然气 5000*108m3 /a，其中进口 LNG1000*108m3 /a 计 （相当于日本目前的进口量）， 可用冷能折合电能为 257*10¾Wh/a， 相当于一个 600*104kW电站的年发电量。 因此如何使 LNG实现技术、 管理机制、 市场运作等各方面 的突破， 力争使大幅度降低 LNG的能耗， 在取得巨大的节能和经济效益同时， 推动包括 空分、煤富氧气化在内的大型冷能产业链的快速发展， 以期为我国全面实现循环型经济 和节约型经济做出贡献， 值得深入思考。 同时， 中国经济的快速发展和模式转型决定了 大规模利用 LNG的绝对必要性， 并提供了宏大的用户市场。
传统天然气的液化流程主要有以下三种：
1、 级联式液化流程 （也称阶式液化流程、 复叠式液化流程或串联蒸发冷凝液化流 程）， 主要应用于基本负荷型天然气液化装置；
2、 混合制冷剂液化流程： 即所谓的 MRC液化流程， MRC是以 C1至 C5的碳氢化合 物， 以及 N2等五种以上的多组分混合制冷剂为工质， 进行逐级冷凝、 蒸发、节流膨胀得 到不同温度水平的制冷量， 以达到逐步冷却和液化天然气的目的。 MRC既达到类似级联 式液化流程的目的， 有克服了其系统复杂的缺点。 自 20世纪 80年代以来， 对于基本负 荷型天然气液化装置， 新建与扩建的基本负荷型天然气液化流程， 几乎毫无例外地采用 丙烷预冷混合制冷剂液化流程；
3、 带膨胀机的液化流程： 带膨胀机液化流程， 是指利用制冷剂再透平膨胀机中的 克劳德循环， 实现天然气液化的流程。气体在膨胀机中膨胀做功的同时， 降低温度并回 收功。根据制冷剂的不同， 可分为氮气膨胀液化流程和天然气膨胀液化流程。这类流程 的优点是： （1 )流程简单、 调节灵活、 工作可靠、 易启动、 易操作、 维修方便； （2 )用 天然气本身作工质时， 能省去专门生产、 运输、 储运冷冻剂的费用。 缺点是： （1 )送入 装置的气流需全部深度干燥； （2) 回流压力低， 换热面积大、 设备金属投入量大； （3) 受低压用户多少的限制； （4)液化率低， 如再循环， 则在增加循环压缩机后， 功耗大大 增加。 由于带膨胀机的液化流程操作比较简单， 投资适中， 特别适用于液化能力较小的 调峰型天然气液化装置。
附图 1是级联式天然气液化流程示意图。
附图 2是 APCI丙烷预冷混合制冷剂液化流程示意图。
附图 3是天然气膨胀液化流程， 图 3中： 1-脱水剂， 2-脱二氧化碳塔， 3-水冷却器， 4-返回气压缩机， 5、 6、 7-换热器， 8-过冷器， 9-储罐， 10-膨胀机， 11-压缩机。
附图 4是氮气膨胀液化流程， 图 4中： 1-预处理装置， 2、 4、 5-换热器， 3-重烃分 离器， 6-氮气提塔， 7-透平膨胀机， 8-氮-甲烷分离塔， 9-循环压缩机。
附图 5是带丙烷预冷的天然气膨胀液化流程示意图， 图 5中： 1、 3、 5、 6、 7-换热 器， 2、 4-丙烷换热器， 8-水冷却器， 9-压缩机， 10-制动压缩机， 12、 13、 14-气液分 上述传统天然气液化流程设计的主要理论基础是热力学，即采用同温差的卡诺逆循 环分析天然气液化过程， 循环的经济性指标是制冷系数， 就是得到的收益和耗费的代价 之比值， 并且以大气环境温度 Γ。与温度为 7^低温热源 （如冷库）之间的一切制冷循环， 以逆向卡诺循环的制冷系数为最高：
' τ0 - Tc 上式中的 为制冷系数， q2为循环的制冷量， w。为循环所消耗的净功。 实际循环效率通常采用实际循环的制冷系数与理论循环系数的比值进行描述， 但其 理论基础是以卡诺逆循环对制冷过程进行循环分析。
实际上， 卡诺在 "关于热动力的见解" 的论文中， 得出的结论为： "在两个不同温 度的恒温热源之间工作的所有热机， 以可逆热机的效率为最高。" 即被后人称之为卡诺 定理， 按理想气体状态方程进行整理得出的卡诺循环的热效率为： η = 1 -^ (2)
Ά
公式 （2) 中的高温热源的温度 7；与低温热源的温度为 Γ2均高于大气环境温度 Γ。， 并可以得出以下几点重要结论： 1 ) 卡诺循环的热效率只决定于高温热源和低温热源的温度， 也就是工质吸热和放 热时的温度， 提高 7和 Γ2， 可以提高热效率。
2) 卡诺循环的热效率只能小于 1， 绝不能等于 1， 因为 7； =∞或7 =0都不可能实 现。这就是说，在循环发动机中即使在理想情况下，也不可能将热能全部转化为机械能， 热效率当然更不可能大于 1。
3) 当 7 = 7 时， 循环热效率等于 0， 它表明， 在温度平衡的体系中， 热能不可能 转化为机械能， 热能产生动力一定要有温度差作为热力学条件， 从而验证了借助单一热 源连续做功的机器是制造不出的， 或第二类永动机是不存在的。
4) 卡诺循环及其热效率公式在热力学的发展上具有重大意义。 首先， 它奠定了热 力学第二定律的理论基础； 其次， 卡诺循环的研究为提高各种热动力机热效率指出了方 向， 近可能提高工质的吸热温度和尽可能降低工质的放热温度， 使放热在接近可自然得 到的最低温度即大气温度时进行。卡诺循环中所提出的利用绝热压缩以提高气体吸热温 度的方法， 至今在以气体为工质的热动力机中仍普遍采用。
5) 卡诺循环的极限点是大气环境温度， 对低于环境温度的制冷过程循环， 卡诺循 环并没有给出明确的答案。
但是运用热力学的基本理论并不能对天然气液化装置循环过程做出简洁、 明了、 直 观的解释， 每生产一吨 LNG的动力及公用设施耗电量约为 850度， 过程的能源消耗量极 大。
爱因斯坦曾对经典热力学做过评价： "一种理论， 其前提越简单， 所涉及的事物越 多， 其适应范围愈广泛， 它给人们的印象就越深刻。 "对制冷领域的基本理论探索， 也 应继承和发扬这个优点。
因此对天然气液化循环过程进行研究， 真正找到制冷装置循环的理论基础， 找到改 进流程的正确方向， 并在此理论基础上组织新的天然气液化装置流程， 较大幅度降低天 然气液化装置的能耗， 成为天然气液化技术领域研究的难点。
发明内容
本发明的目的就是为解决卡诺定理应用于天然气液化装置循环理论分析的不完善 性， 提出对应于热力学理论的新的制冷理论即冷力学理论， 并提出应用该原理设计的新 的天然气等压液化装置， 克服传统天然气液化流程复杂、 能耗高、 必须配套超量的公共 设施如循环冷却水系统等缺点， 保留并发扬带膨胀机液化流程的优点， 较大幅度地降低 能耗 30%以上， 同时实现天然气的等压冷凝， 设备维修及材料备用量大幅度减少， 从而 实现天然气液化技术的变革。
对应于传统热力学范畴， 提出冷力学的基本概念： 对于低于大气环境温度的环境称 之为冷源， 相对于高于环境温度的热源； 相应于热能、 热量， 提出对应的冷能、 冷量概 念； 所述的制冷装置， 是指消耗机械功来实现冷能从大气环境向低温冷源或者从低温冷 源向更低温冷源的转移。在实现冷能转换时，均需要某些物质作为制冷装置的工作物质， 称为制冷工质。
制冷过程中冷能的传递遵循能量转化和守恒定律。
为描述制冷过程中冷量传递的方向、 条件和限度， 提出冷力学第二定律： 冷力学第 二定律的实质跟热力学第二定律的实质是一样的， 同样遵循 "能质衰贬原理"， 即不同 形式的冷能， 在转换成功量的能力上是有 "质" 的差别的； 即使是同一种形式的冷能， 其存在状态不同时， 它的转换能力也不同的。一切冷能传递的实际过程， 总是朝着能质 下降的方向进行， 一切冷能总会自发向大气环境方向转换。冷能能质的提高过程不可能 自动、单独地进行， 一个能质的提高的过程必然伴随着另一个能质的下降的过程同时发 生， 这个能质下降的过程就是实现能质升高过程的必要的补偿条件， 即以能质下降为代 价、 作为补偿来推动能质升高过程的实现。 在实际过程中， 作为代价的能质下降过程， 必须足以补偿能质升高的过程， 以满足总的能质必定下降的普遍规律。 因此， 在一定的 能质下降的补偿条件下， 能质升高的过程必然有一个最高的理论限度。只有在完全可逆 的理想条件下，才能达到这个理论限度，这时，能质升高值正好等于能质下降的补偿值， 使总的能质保持不变。可见， 可逆过程是纯理想化的能质守恒过程； 在不可逆过程中总 的能质必然下降； 在任何情况下都不可能实现使孤立系统总的能质升高的过程。这就是 能质衰贬原理的物理内涵， 是冷力学第二定律的实质， 也是热力学第二定律的实质， 它 揭示了一切宏观过程必须遵循的、 有关过程进行方向、 条件及限度的客观规律。
描述冷力学第二定律的基本公式为：
T
η = 1―" ci ( 3)
c τ 公式 （3) 中， Tc2<Tcl <To， To为环境温度， 均为开氏温标。
相对环境温度 To而言， 冷源在 Tcl、 Tc2下的最大冷效率为： 设为 q2循环的制冷量， w。为循环所消耗的净功， 则在冷源温度为 Tel时：
Figure imgf000006_0001
同样， 在冷源温度为 Tc2时：
Figure imgf000006_0002
从公式 （4)至 （7)不难看出， 冷力学的效率为 0到 1之间， 由于实际过程中不可 逆性的不可避免， 制冷循环效率总是小于 1的；
环境温度 To确定时， 冷源温度越低， 从该冷源输入同样的功， 获得的制冷量越多， 这为构建新的天然气液化装置流程指明了方向。
需要说明的是：
(1) 冷量是自发从低温冷源向环境温度传递的；
(2) 不可能把冷量从低温冷源传到更低的冷源而不引起其他变化；
(3) 冷量从低温冷源传递向环境时， 与外界交换的功量为 W。， 其中包含对环境所 做的无用功 ρ。( 。 - )， ρ。为大气压力， Vo为环境温度下的体积， Vc为冷源温度下的 体积，所能做的最大可逆有用功为：
(^)max =W0 - P0(V0 -Fc) = (l-¾0 - p0(V0 -Vc)
To
(4) 冷量从低温冷源传递向环境时， 向环境传递的无用能为：
E —
无用 _ To 向环境传递的无用功为： P。( 。 - ^ ) 对应于热量的有用能 "口"、 无用能 "烬"， 对热量、 冷量取水火会意， 对于冷量 的有用能， 取名为 "冷量涟" ， 冷量向环境传递的无用能称为 "冷量烬" ， "W读 音为 "尽" 。
(5)冷能向环境温度传递时， 向外做功的最佳型式为采用塞贝克（Seebeck)效应 的温差发电机， 即冷力发电机；
(6) 冷力学中能量必须、 也必然要符合能量转化和守恒定律； ( 7 ) 通过借鉴有限时间热力学的构思， 可以发展有限时间冷力学基本理论；
( 8 ) 不能脱离环境来评价冷量的品位；
( 9 ) 冷力学和热力学是能量学中的两个分支， 既存在对立的一面， 又存在着统一 的一面： 低温制冷循环中， 在遵循冷力学第二定律的前提下， 在低温环境下构造的制冷 剂工质的循环过程又遵循朗肯循环原理， 重新又回到卡诺定律， 恰好符合中国传统美学 中阴中有阳、 阴阳相济的原理。
从上述观点可以看出， 假设的冷力学具有和热力学对称的理论框架体系， 符合科学 美学的基本原则， 即相反相成、 对称原则。
基于上述冷力学基本原理， 本发明提出不同于传统天然气液化装置的流程组织， 低 能耗实现天然气等压液化， 并有效降低天然气液化装置的能耗， 使天然气的比功耗降低 至 0. 24kW · h/kg左右。
本发明的目的是通过以下措施实现的：
一种天然气等压液化装置， 该液化装置包括天然气与处理系统、 液化系统、补冷系 统、储存系统、控制系统和消防系统， 本发明仅列出最重要的组成部分即液化流程示意 图， 未详细说明的内容按传统的成熟技术进行配套， 实现天然气等压液化的工艺步骤如 下：
( 1 ) 原料天然气 1经预处理装置 2除去水分、 二氧化碳， 进入冷交换器 3、 分离 器 4分离出液态重烃组分 5， 再经冷交换器 6成为预冷入塔原料气 7;
(2) 预冷入塔原料气 7进入下塔 8， 经冷凝蒸发器 9产生的过冷甲烷液体回流进 行精熘， 等压冷凝产生液化天然气 11即 LNG， LNG送入 LNG储罐 12;
( 3 ) 冷凝蒸发器中等压冷凝产生的纯甲烷液体 13引入液态纯甲烷储罐 14;
(4) 所述装置的补冷系统， 是指从制冷剂贮罐 19出来的液态制冷剂 20， 经低温 液体泵 21、 回冷器 18形成的制冷剂气液混合物 22进入上塔 10， 通过冷凝蒸发器 9使 下塔的甲烷气冷凝产生液态甲烷， 从上塔 10出来的出塔低温制冷剂 15， 经冷交换器 6、 冷交换器 3冷却原料天然气 1， 形成制冷工质过热蒸汽 16， 经膨胀机 17膨胀降压降温 后， 再经回冷器 21、 节流阀 23， 返回制冷剂贮罐 19， 通过冷凝蒸发器 9、 冷交换器 6、 冷交换器 3对天然气液化系统补入所需的冷量， 从而形成制冷剂的冷力循环回路； 通过 设置的节流阀 23可以方便调节补冷系统的压力。
所述的膨胀机 17的制动设备 24采用风机、 电机、 液压泵或压气机。
下塔 8上部的甲烷也可直接引入上塔 10经液氮洗涤产生液态纯甲烷，从上塔 10底 部引出送至液态纯甲烷储罐 14。
所述的等压分离， 是指进入天然气液化系统的原料天然气， 无需像传统的天然气液 化工艺那样节流降压进行液化， 送来的原料天然气 1仅有沿程设备及管道的阻力损失， 可以视为等压液化过程。
所述的液化系统， 包括下塔 8、 冷凝蒸发器 9、 上塔 10， 采用一体式或分体式的结 构。
所述的制冷剂在标准压力下的沸点低于或等于甲烷， 包括但不限于甲烷、氮气、氩 气、 氦气、 氢气等一种或多种气体组成的混合气体， 如能确保安全， 也可使用氢气或液 氢， 优选的为氮气。
所述的制冷剂贮罐 19采用必要的绝热保冷措施， 如采用绝热真空容器、 珠光砂等 隔热保冷材料。
所述的冷交换器 6、 冷交换器 3、 回冷器 18采用管壳式、 板翅式、 微通道或其他型 式的换冷器， 其结构及换冷元件与传统的天然气液化流程中的管壳式换热器、板翅式换 热器、 微通道换热器等相同， 只是为了与制冷体系相对应而更换准确的名称。
所述的冷交换器 3、 冷交换器 6、 分离器 4、 回冷器 18可设置一个或多个。
本发明中未说明的设备及其备用系统、 管道、 仪表、 阀门、 保冷、 具有调节功能旁 路设施等采用公知的传统天然气液化系统的成熟技术进行配套。
设有与本发明的天然气液化装置配套的安全、 调控设施， 使装置能经济、 安全、 高 热效率运行， 达到节能降耗、 环保的目的。
本发明的装置同样适用于其他气体的液化，采用的制冷剂在标准大气压下的沸点低 于或等于相应的待液化气体在标准大气压下的沸点。
本发明相比现有技术具有如下优点：
1、 节能效果显著： 取消传统天然气液化系统循环的循环压气机， 利用液体的接近 不可压缩流体的性质， 采用低温液体循环泵进行增压补冷， 实现天然气的等压液化， 能 够有效提高制冷循环的效率， 与传统天然气液化装置相比， 相同制冷量的节能率可达 30%以上， 每吨液化天然气较传统的先进流程至少节电 200度。
2、 等压冷凝产生的 LNG或液态纯甲烷， 能够节省传统 LNG或纯液态甲烷的增压过 程消耗的电功。
3、 可通过低压使天然气液化， 再对液化天然气增压的方法节省传统天然气液化过 程的气体压缩功， 与天然气液化系统配套的公用工程耗电量减少 80%以上。 4、 流程设置更加简洁， 液化系统的潜力得到充分发挥， 操作弹性大， 运行调节更 加灵活方便。
5、 设备及材料的备用量有较大幅度的减少。
6、 完全能够替代传统的主流基本负荷型天然气液化装置如丙烷预冷混合制冷剂液 化流程， 成为基地型天然气液化装置、 调峰型天然气液化装置的主流流程。
附图说明
图 1是级联式天然气液化流程示意图；
图 2是 APCI丙烷预冷混合制冷剂液化流程示意图；
图 3是天然气膨胀液化流程：
图 3 中： 1-脱水剂， 2-脱二氧化碳塔， 3-水冷却器， 4-返回气压缩机， 5、 6、 7- 换热器， 8-过冷器， 9-储罐， 10-膨胀机， 11-压缩机。
图 4是氮气膨胀液化流程：
图 4中： 1-预处理装置， 2、 4、 5-换热器， 3-重烃分离器， 6-氮气提塔， 7-透平膨 胀机， 8-氮-甲烷分离塔， 9-循环压缩机。
图 5是带丙烷预冷的天然气膨胀液化流程示意图：
图 5中： 1、 3、 5、 6、 7-换热器， 2、 4-丙烷换热器， 8-水冷却器， 9-压缩机， 10- 制动压缩机， 12、 13、 14-气液分离器。
图 6是本发明的一种天然气等压液化装置流程示意图：
图 6中： 1-原料天然气， 2-预处理装置， 3-冷交换器， 4-重烃分离器， 5-液态重烃 组分， 6-冷交换器， 7-预冷入塔原料气， 8-下塔， 9-冷凝蒸发器， 10-上塔， 11-LNG, 12-LNG储罐， 13-纯液态甲烷， 14-纯液态甲烷储罐， 15-出塔低温制冷剂， 16-制冷剂 过热蒸汽， 17-膨胀机， 18-回冷器， 19-制冷剂储罐， 20-液体制冷剂， 21-低温液体泵， 22-制冷剂气液混合物， 23-节流阀， 24-制动设备。
具体实施方式
以下结合附图和具体实施例对本发明作进一步详细描述。
实施例 1:
如图 6所示， 一种天然气等压液化装置， 制冷剂采用氮气， 具体实施例如下：
( 1 ) 原料天然气 1经预处理装置 2除去水分、 二氧化碳， 进入冷交换器 3、 重烃 分离器 4分离出液态重烃组分 5， 再经冷交换器 6成为预冷入塔原料气 7;
(2) 预冷入塔原料气 7进入下塔 8， 经冷凝蒸发器 9产生的过冷甲烷液体回流进 行精熘， 等压冷凝产生液化天然气 11即 LNG1， LNG送入 LNG储罐 12;
(3 ) 冷凝蒸发器中等压冷凝产生的纯甲烷液体 13引入液态纯甲烷储罐 14;
(4)从制冷剂贮罐 19出来的液态制冷剂 20， 经低温液体泵 21、 回冷器 18形成的 制冷剂气液混合物 22进入上塔 10， 通过冷凝蒸发器 9使下塔的甲烷气冷凝产生液态甲 烷， 从上塔 10出来的出塔低温制冷剂 15， 经冷交换器 6、 冷交换器 3冷却原料天然气 1， 形成制冷工质过热蒸汽 16， 经膨胀机 17膨胀降压降温后， 再经回冷器 21、 节流阀 23， 返回制冷剂贮罐 19， 通过冷凝蒸发器 9、 冷交换器 6、 冷交换器 3对天然气液化系 统补入所需的冷量， 从而形成制冷剂的冷力循环回路； 通过设置的节流阀 23可以方便 调节补冷系统的压力。
所述的膨胀机 17的制动设备 24采用压气机， 用于对原料天然气进行增压。
所述的制冷工质贮罐 19采用必要的绝热保冷措施， 如采用绝热真空容器、 珠光砂 等隔热保冷材料。
本发明中未说明的设备及其备用系统、 管道、 仪表、 阀门、 保冷、 具有调节功能旁 路设施等采用公知的传统天然气液化系统的成熟技术进行配套。
设有与本发明的天然气液化装置配套的安全、 调控设施， 使装置能经济、 安全、 高 热效率运行， 达到节能降耗、 环保的目的。
虽然本发明已以较佳实施例公开如上， 但它们并不是用来限定本发明， 任何熟悉此 技艺者， 在不脱离本发明之精神和范围内， 自当可作各种变化或润饰， 同样属于本发明 之保护范围。 因此本发明的保护范围应当以本申请的权利要求所界定的为准。

Claims

WO 2014/114264 权利 要求 书 PCT/CN2014/071402
1. 一种天然气等压液化装置， 该装置包括天然气预处理系统、 预冷系统、 液化系统、 补冷系统、 储存系统、 控制系统和消防系统， 其特征在于：
所述装置的补冷系统， 是指从制冷剂贮罐 （19 ) 出来的液态制冷剂 （20)， 经低温液体 泵 （21 )、 回冷器 （18 ) 形成的制冷剂气液混合物 （22 )进入上塔 （10)， 通过冷凝蒸发 器 (9)使下塔 (8)的甲烷气冷凝产生液态甲烷、 或使下塔 (8)引入上塔的甲烷冷凝形成液态 甲烷， 从上塔 (10)出来的出塔低温制冷剂 (15)， 经冷交换器 (6)、 冷交换器 (3)冷却原料天 然气（1 )，形成制冷工质过热蒸汽 (16)，经膨胀机 (17)、回冷器 (21)，返回制冷剂贮罐 (19)， 从而形成制冷剂的冷力循环回路。
2. 根据权利要求 1所述的装置， 其特征在于：
设有节流阀 (23):
从制冷剂贮罐 (19)出来的液态制冷齐 IJ(20)， 经低温液体泵 (21)、 回冷器 (18)形成的制冷剂 气液混合物 (22)进入上塔 (10)， 通过冷凝蒸发器 (9)使下塔 (8)的甲烷气冷凝产生液态甲 烷、 或使下塔 (8)引入上塔的甲烷冷凝形成液态甲烷， 从上塔 (10)出来的出塔低温制冷剂 (15)， 经冷交换器 (6)、 冷交换器 (3)冷却原料天然气 (1)， 形成制冷工质过热蒸汽 (16)， 经 膨胀机 (17)、 回冷器 (21)、 节流阀 (23)， 返回制冷剂贮罐 (19)， 从而形成制冷剂的冷力循 环回路。
3. 根据权利要求 1所述的装置， 其特征在于：
所述的膨胀机 (17)的制动设备 (24)采用风机、 电机、 液压泵或压气机。
4. 根据权利要求 2所述的装置， 其特征在于：
所述的膨胀机 (17)的制动设备 (24)采用风机、 电机、 液压泵或压气机。
5. 根据权利要求 1所述的装置， 其特征在于：
所述的液化系统包括下塔 (8)、 冷凝蒸发器 (9)、 上塔 (10) ， 采用一体式或分体式的结构。
6. 根据权利要求 2所述的装置， 其特征在于：
所述的液化系统包括下塔 (8)、 冷凝蒸发器 (9)、 上塔 (10)， 采用一体式或分体式的结构。
7. 根据权利要求 3所述的装置， 其特征在于：
所述的液化系统包括下塔 (8)、 冷凝蒸发器 (9)、 上塔 (10)， 采用一体式或分体式的结构。
8. 根据权利要求 4所述的装置， 其特征在于：
所述的液化系统包括下塔 (8)、 冷凝蒸发器 (9)、 上塔 (10)， 采用一体式或分体式的结构。
9. 根据权利要求 1至 8之一所述的装置， 其特征在于：
所述制冷剂在标准压力下的沸点低于或等于甲烷， 包括甲烷、 氮气、 氩气、 氦气、 氢气 中的一种气体或多种气体组成的混合物。
10. 根据权利要求 1至 8之一所述的装置， 其特征在于：
本发明的装置同样适用于其他气体的液化，采用的制冷剂在标准大气压下的沸点低于或 等于相应的待液化气体在标准大气压下的沸点。
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