CN117889349A - LNG gasification system for generating power by utilizing cold energy and LNG receiving station - Google Patents

LNG gasification system for generating power by utilizing cold energy and LNG receiving station Download PDF

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Publication number
CN117889349A
CN117889349A CN202410250713.7A CN202410250713A CN117889349A CN 117889349 A CN117889349 A CN 117889349A CN 202410250713 A CN202410250713 A CN 202410250713A CN 117889349 A CN117889349 A CN 117889349A
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CN
China
Prior art keywords
condenser
lng
expander
cold
power generation
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Pending
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CN202410250713.7A
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Chinese (zh)
Inventor
张雪辉
马宏涛
常学煜
付文秀
朱阳历
陈海生
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Institute of Engineering Thermophysics of CAS
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Institute of Engineering Thermophysics of CAS
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Priority to CN202410250713.7A priority Critical patent/CN117889349A/en
Publication of CN117889349A publication Critical patent/CN117889349A/en
Pending legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C9/00—Methods or apparatus for discharging liquefied or solidified gases from vessels not under pressure
    • F17C9/02—Methods or apparatus for discharging liquefied or solidified gases from vessels not under pressure with change of state, e.g. vaporisation
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C13/00—Details of vessels or of the filling or discharging of vessels
    • F17C13/06—Closures, e.g. cap, breakable member
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2201/00—Vessel construction, in particular geometry, arrangement or size
    • F17C2201/01—Shape
    • F17C2201/0104—Shape cylindrical
    • F17C2201/0109—Shape cylindrical with exteriorly curved end-piece
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2201/00—Vessel construction, in particular geometry, arrangement or size
    • F17C2201/03—Orientation
    • F17C2201/035—Orientation with substantially horizontal main axis
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2201/00—Vessel construction, in particular geometry, arrangement or size
    • F17C2201/05—Size
    • F17C2201/052—Size large (>1000 m3)
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2205/00—Vessel construction, in particular mounting arrangements, attachments or identifications means
    • F17C2205/03—Fluid connections, filters, valves, closure means or other attachments
    • F17C2205/0302—Fittings, valves, filters, or components in connection with the gas storage device
    • F17C2205/0323—Valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2205/00—Vessel construction, in particular mounting arrangements, attachments or identifications means
    • F17C2205/03—Fluid connections, filters, valves, closure means or other attachments
    • F17C2205/0302—Fittings, valves, filters, or components in connection with the gas storage device
    • F17C2205/0323—Valves
    • F17C2205/0335—Check-valves or non-return valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2221/00—Handled fluid, in particular type of fluid
    • F17C2221/03—Mixtures
    • F17C2221/032—Hydrocarbons
    • F17C2221/033—Methane, e.g. natural gas, CNG, LNG, GNL, GNC, PLNG
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2223/00—Handled fluid before transfer, i.e. state of fluid when stored in the vessel or before transfer from the vessel
    • F17C2223/01—Handled fluid before transfer, i.e. state of fluid when stored in the vessel or before transfer from the vessel characterised by the phase
    • F17C2223/0146—Two-phase
    • F17C2223/0153—Liquefied gas, e.g. LPG, GPL
    • F17C2223/0161—Liquefied gas, e.g. LPG, GPL cryogenic, e.g. LNG, GNL, PLNG
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2223/00—Handled fluid before transfer, i.e. state of fluid when stored in the vessel or before transfer from the vessel
    • F17C2223/03—Handled fluid before transfer, i.e. state of fluid when stored in the vessel or before transfer from the vessel characterised by the pressure level
    • F17C2223/033—Small pressure, e.g. for liquefied gas
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2225/00—Handled fluid after transfer, i.e. state of fluid after transfer from the vessel
    • F17C2225/01—Handled fluid after transfer, i.e. state of fluid after transfer from the vessel characterised by the phase
    • F17C2225/0107—Single phase
    • F17C2225/0123—Single phase gaseous, e.g. CNG, GNC
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2227/00—Transfer of fluids, i.e. method or means for transferring the fluid; Heat exchange with the fluid
    • F17C2227/01—Propulsion of the fluid
    • F17C2227/0128—Propulsion of the fluid with pumps or compressors
    • F17C2227/0157—Compressors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2270/00—Applications
    • F17C2270/05—Applications for industrial use
    • F17C2270/0581—Power plants

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Filling Or Discharging Of Gas Storage Vessels (AREA)

Abstract

The invention discloses an LNG gasification system for generating power by utilizing cold energy, and relates to the technical field of LNG gasification systems. The LNG gasification system for generating power by utilizing cold energy comprises a thermal circulation loop and a power generation circulation loop; the internal circulation of the thermal circulation loop is provided with a heating working medium, and the thermal circulation loop comprises a compressor, a first evaporator, a third condenser, an expansion valve and a second evaporator; the power generation circulation loop internally circulates a power generation working medium and comprises a cold path, a first branch and a second branch of the first vaporizer; the first branch comprises a first expander, and the first expander is connected with the generator; the second branch comprises a second expander, and an output shaft of the second expander is connected with an input shaft of the compressor. The LNG gasification system for generating power by utilizing cold energy solves the technical problems of high combustion loss and cold energy waste in the LNG gasification process in the prior art, and has the advantages of low energy consumption and high economic benefit.

Description

LNG gasification system for generating power by utilizing cold energy and LNG receiving station
Technical Field
The invention relates to the technical field of LNG gasification systems, in particular to an LNG gasification system and an LNG receiving station for generating power by utilizing cold energy.
Background
LNG (liquefied natural gas) is a clean energy source, and for mass storage and transportation, natural gas is usually liquefied into LNG during transportation, and the LNG is transported to an LNG receiving station by sea and gasified for use by a user, and the LNG gasification system is a device for gasifying LNG.
In the process of implementing the present invention, the inventor finds that at least the following problems exist in the prior art:
Large LNG receiving stations, LNG vaporization stations, LNG liquid filling stations, etc., and LNG vaporization is achieved by fuel combustion, such as submerged combustion type vaporizers, based on overall investment and installation costs considerations. However, the method has the problem of large fuel consumption, particularly in winter, the fuel used in the LNG gasification process is further greatly increased, and the problem is particularly obvious in the current large environment with energy conservation and emission reduction. In addition, because LNG can release a large amount of cold energy when gasifying, how to utilize the cold energy of LNG effectively also has great significance to energy saving, emission reduction and economic benefits improvement.
Based on the above, how to reduce the combustion loss and the cold energy waste in the LNG gasification process and improve the economic benefit of the LNG gasification process is a problem to be solved by those skilled in the art.
Disclosure of Invention
The invention aims to provide an LNG gasification system with low energy consumption and high economic benefit.
To achieve the object, in one aspect, there is provided an LNG gasification system for generating power using cold energy, including a thermal circulation loop and a power generation circulation loop; the internal circulation of the thermal circulation loop is provided with a heating working medium, and the thermal circulation loop comprises a compressor, a first evaporator, a third condenser, an expansion valve and a second evaporator; the heating working medium flows into the hot path inlet of the first vaporizer through the outlet of the compressor, flows out of the hot path outlet of the first vaporizer and then enters the hot path inlet of the third condenser, flows out of the hot path outlet of the third condenser and then enters the inlet of the expansion valve, flows out of the outlet of the expansion valve and then enters the cold path inlet of the second vaporizer, flows out of the cold path outlet of the second vaporizer and then returns to the compressor; the cold path of the third condenser is communicated with an LNG pipeline; the power generation circulation loop internally circulates a power generation working medium and comprises a cold path, a first branch and a second branch of the first vaporizer; the power generation working medium flows out from a cold path outlet of the first vaporizer and then enters the first branch and the second branch respectively; the first branch comprises a first expander, and the first expander is connected with a generator; the second branch comprises a second expander, and an output shaft of the second expander is connected with an input shaft of the compressor.
Further, the power generation circulation loop also comprises a storage tank and a buffer tank; the storage tank is used for storing low-temperature and low-pressure power generation working media, and the buffer tank is used for storing high-temperature and high-pressure power generation working media; the power generation working medium flowing out of the storage tank enters the cold path inlet of the first vaporizer, flows out of the cold path outlet of the first vaporizer and enters the buffer tank, and flows out of the outlet of the buffer tank and then enters the first branch and the second branch respectively.
Further, the power generation circulation loop also comprises a circulation pump and a first control valve, wherein the outlet of the storage tank is communicated with the inlet of the circulation pump, and the outlet of the circulation pump is communicated with the cold path inlet of the first vaporizer; the first control valve is located on a line between the outlet of the reservoir and the inlet of the circulation pump.
Further, the first branch further comprises a first condenser, a hot path inlet of the first condenser is communicated with an air outlet of the first expander, and a cold path of the first condenser is communicated with an LNG pipeline.
Further, the second branch further comprises a second condenser, a hot path inlet of the second condenser is communicated with an air outlet of the second expander, and a cold path of the second condenser is communicated with an LNG pipeline.
Further, the first branch further comprises a first speed regulating valve, and the first speed regulating valve is positioned at the inlet end of the first expander; and/or, the second branch further comprises a second speed regulating valve, and the second speed regulating valve is positioned at the inlet end of the second expander.
Further, the first branch further comprises a first check valve, and the first check valve is positioned at the outlet end of the first expander; and/or the second branch further comprises a second check valve, and the second check valve is positioned at the outlet end of the second expander.
Further, the power generation working medium uses propane, and the heating working medium uses R410A.
On the other hand, still provide an LNG receiving station, including foretell LNG gasification system and the natural gas export pipeline that utilizes cold energy to generate electricity, the hot way of second vaporizer lets in waste heat and heat, the low reaches of LNG pipeline lets in the natural gas export pipeline.
Further, the heat circuit of the second vaporizer utilizes a heat source of seawater.
Further, the thermal cycle loop includes the third condenser; the first branch of the power generation cycle loop further comprises a first condenser, and the second branch further comprises a second condenser; the cold path of the first condenser, the cold path of the second condenser and the cold path of the third condenser are respectively connected in parallel to the LNG pipeline; the cold path outlet of the first condenser is connected with the upstream of the cold path outlet of the second condenser, and the cold path outlet of the second condenser is connected with the upstream of the cold path outlet of the third condenser.
The invention has the beneficial effects that:
The LNG gasification system for generating power by utilizing cold energy in the scheme comprises a thermal circulation loop and a power generation circulation loop. The circulating working medium in the thermal circulation loop is a heating working medium. The thermal circulation loop comprises a compressor, a first evaporator, a third condenser, an expansion valve and a second evaporator. The compressor is used for compressing the heating working medium to be changed into the high-temperature and high-pressure heating working medium, so that the high-temperature and high-pressure heating working medium flows out from an outlet of the compressor. The high-temperature and high-pressure heating working medium flows into a hot path inlet of the first vaporizer through an outlet of the compressor, a cold path of the first vaporizer is positioned in the power generation circulation loop, a power generation working medium is arranged in the cold path of the first vaporizer, and the heating working medium supplies heat for the power generation working medium through the first vaporizer. The temperature of the heating working medium is reduced after flowing out of the heat path outlet of the first evaporator, the heating working medium then enters the heat path inlet of the third condenser, the cold path of the third condenser is communicated with the LNG pipeline, the temperature of the heating working medium in the third condenser is further reduced, the low-temperature high-pressure liquid heating working medium flowing out of the heat path outlet of the third condenser enters the expansion valve for decompression, the working medium in a low-temperature low-pressure liquid or wet steam state flowing out of the expansion valve outlet enters the cold path inlet of the second evaporator, the heat path of the second evaporator utilizes an external heat source, therefore, the temperature of the low-temperature heating working medium in the second evaporator is increased again and is completely gasified, and the gaseous heating working medium with the increased temperature flows out of the cold path outlet of the second evaporator and returns to the compressor to start the next circulation.
The power generation circulation loop internally circulates power generation working medium, and comprises a cold path, a first branch and a second branch of the first vaporizer; the power generation working medium flows out from the cold path outlet of the first evaporator and then enters the first branch and the second branch respectively. The first branch comprises a first expander, the first expander is connected with the generator, and the warmed power generation working medium expands in the first expander to generate power. The second branch comprises a second expander, the warmed power generation working medium expands in the second expander to do work, and an output shaft of the second expander is connected with an input shaft of a compressor in the thermal circulation loop to provide power for the compressor in the thermal circulation loop.
In summary, in the LNG gasification system for generating power by utilizing cold energy in the scheme, a heating working medium is arranged in a thermal circulation loop, and the heating working medium provides heat for gasification of liquefied natural gas in an LNG pipeline through a thermal path of a third condenser. The temperature of the heating working medium after providing heat for the gasification of the liquefied natural gas in the LNG pipeline can be reduced, at the moment, the temperature of the heating working medium is increased again through the compressor of the thermal circulation loop, the heating working medium after the temperature increase enters the thermal path of the third condenser again to provide heat for the gasification of the liquefied natural gas in the LNG pipeline, and a circulation loop for providing heat for the gasification of the liquefied natural gas in the LNG pipeline is formed, so that the supplement of external heat is greatly reduced compared with the direct heating of LNG.
According to the LNG gasification system for generating power by utilizing cold energy, heat can be provided for gasification of liquefied natural gas in an LNG pipeline, and LNG gasification is realized. In the gasification process of LNG, the external heat source provides heat for the second vaporizer, so that consumption of the external heat source required for heating the LNG is greatly reduced, and the external heat source can use industrial waste heat to improve energy utilization efficiency. Meanwhile, the LNG gasification system utilizing cold energy to generate electricity can generate electricity through the first expansion machine, collect the electricity through the energy storage system, and can be used in production and life, so that economic benefit is improved. In addition, the LNG gasification system utilizing cold energy to generate power can further provide power for the thermal circulation loop of the LNG gasification system through the second expander, so that the input energy consumption required by the LNG gasification system is further reduced.
The LNG receiving station of this scheme includes foretell LNG gasification system and the natural gas outward pipeline that utilizes cold energy to generate electricity, and natural gas outward pipeline is the pipeline of carrying the natural gas after the gasification promptly, and waste heat is utilized in the heat way of second vaporizer, and when LNG transported through the boats and ships, the heat way of second vaporizer still can utilize the heat of sea water. Based on this, the LNG gasification system of utilizing cold energy electricity generation and LNG receiving station of this scheme have the advantage that the energy consumption is low, economic benefits is high.
Drawings
Fig. 1 is a flowchart of an LNG vaporization system for generating power using cold energy in the first embodiment.
In the figure: 1-a storage tank; 2-a first control valve; 3-a circulation pump; 4-a first vaporizer; 5-a buffer tank; 6-a second speed regulating valve; 7-a second expander; 8-a second check valve; 9-a second condenser; 10-a first speed regulating valve; 11-a first expander; 12-a first check valve; 13-a first condenser; 14-a first refrigeration control valve; 15-a second refrigeration capacity control valve; 16-a third refrigeration capacity control valve; 17-a third condenser; an 18-expansion valve; 19-a second vaporizer; 20-compressor.
Detailed Description
In order to make the technical problems solved by the present invention, the technical solutions adopted and the technical effects achieved more clear, the technical solutions of the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings, and it is obvious that the described embodiments are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In the description of the present invention, unless explicitly stated and limited otherwise, the terms "connected," "connected," and "fixed" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art.
In the present invention, unless expressly stated or limited otherwise, a first feature "above" or "below" a second feature may include both the first and second features being in direct contact, as well as the first and second features not being in direct contact but being in contact with each other through additional features therebetween. Moreover, a first feature being "above," "over" and "on" a second feature includes the first feature being directly above and obliquely above the second feature, or simply indicating that the first feature is higher in level than the second feature. The first feature being "under", "below" and "beneath" the second feature includes the first feature being directly under and obliquely below the second feature, or simply means that the first feature is less level than the second feature.
Embodiment one:
As shown in fig. 1, the present embodiment provides an LNG vaporization system that generates power using cold energy, including a thermal circulation loop and a power generation circulation loop. The circulating working medium in the thermal circulation loop is a heating working medium. The thermal cycle includes a compressor 20, a first vaporizer 4, a third condenser 17, an expansion valve 18, and a second vaporizer 19. The compressor 20 is used for compressing the heating medium to be changed into a high-temperature and high-pressure heating medium, so that the high-temperature and high-pressure heating medium flows out from the outlet of the compressor 20. The high-temperature and high-pressure heating working medium flows into the heat path inlet of the first vaporizer 4 through the outlet of the compressor 20 (the cold path of the first vaporizer 4 is positioned in the power generation circulation loop), the temperature of the heating working medium is reduced after flowing out of the heat path outlet of the first vaporizer 4, then the heating working medium enters the heat path inlet of the third condenser 17, the cold path of the third condenser 17 is communicated with the LNG pipeline, the temperature of the heating working medium is further reduced in the third condenser 17, the low-temperature and high-pressure liquid heating working medium flowing out of the heat path outlet of the third condenser 17 enters the expansion valve for decompression, the low-temperature and low-pressure liquid or wet steam working medium flowing out of the expansion valve outlet enters the cold path inlet of the second vaporizer 19, and the heat path of the second vaporizer 19 utilizes an external heat source, so that the low-temperature heating working medium rises again in the second vaporizer 19 and is completely gasified, the gaseous heating working medium with the temperature rising flows out of the cold path outlet of the second vaporizer 19 and returns into the compressor 20, and the next circulation is started.
The power generation working medium circulates in the power generation circulation loop, and the power generation circulation loop comprises the cold path, the first branch and the second branch of the first carburetor 4; the power generation working medium flows out from the cold path outlet of the first vaporizer 4 and then enters the first branch and the second branch respectively. The first branch comprises a first expander 11, the first expander 11 is connected with a generator, and the warmed power generation working medium expands in the first expander 11 to generate power. The second branch comprises a second expander 7, the warmed power generation working medium expands in the second expander 7 to do work, and an output shaft of the second expander 7 is connected with an input shaft of a compressor 20 in the thermal circulation loop to provide power for the compressor 20 in the thermal circulation loop.
In this embodiment, a heating working medium is arranged in the thermal circulation loop, and the heating working medium provides heat for gasification of liquefied natural gas in the LNG pipeline through a thermal path of the third condenser 17. The temperature of the heating working medium after providing heat for the gasification of the liquefied natural gas in the LNG pipeline can be reduced, at the moment, the heating working medium is raised again through the compressor 20 of the thermal circulation loop, the heating working medium after the temperature rise enters the thermal path of the third condenser 17 again to provide heat for the gasification of the liquefied natural gas in the LNG pipeline, and a circulation loop for providing heat for the gasification of the liquefied natural gas in the LNG pipeline is formed, so that the supplement of external heat is greatly reduced compared with the direct heating of LNG.
The LNG gasification system utilizing cold energy to generate electricity can provide heat for gasification of liquefied natural gas in an LNG pipeline, and can realize gasification of LNG. In the gasification process of LNG, heat is supplied to the second vaporizer 19 by an external heat source, the consumption of the external heat source required for heating LNG is greatly reduced, and the external heat source can use industrial waste heat. Meanwhile, the LNG gasification system using cold energy to generate electricity in this embodiment can also generate electricity through the first expander 11, generate electric energy, collect the above electric energy through the energy storage system, and can be used in production and life, thereby improving economic benefits. In addition, the LNG vaporization system using cold energy to generate power in the embodiment can also provide power for its own thermal cycle loop through the second expander 7, so as to further reduce the input energy consumption required by the system. Therefore, the LNG gasification system for generating electricity by utilizing cold energy has the advantages of low energy consumption and high economic benefit.
Further, the power generation circulation loop further comprises a storage tank 1 and a buffer tank 5, wherein the storage tank 1 is used for storing low-temperature low-pressure liquid power generation working media, and the buffer tank 5 is used for storing high-temperature high-pressure gas power generation working media. The power generation working medium flowing out of the storage tank 1 enters the cold path inlet of the first vaporizer 4, flows out of the cold path outlet of the first vaporizer 4 and then enters the buffer tank 5, and flows out of the outlet of the buffer tank 5 and then respectively enters the first branch and the second branch for the first expander and the second expander.
Further, the power generation circulation loop also comprises a circulation pump 3 and a first control valve 2, wherein the outlet of the storage tank 1 is communicated with the inlet of the circulation pump 3, and the outlet of the circulation pump 3 is communicated with the cold path inlet of the first vaporizer 4; the first control valve 2 is located in the line between the outlet of the tank 1 and the inlet of the circulation pump 3. The circulating pump 3 is used for providing circulating power for the power generation circulating loop, and the circulating quantity of the power generation working medium can be increased by increasing the outlet pressure of the circulating pump 3. The first control valve 2 is used for controlling the flow and opening and closing of the power generation working medium flowing out of the storage tank.
Further, the first branch further comprises a first condenser 13, a hot path inlet of the first condenser 13 is communicated with an air outlet of the first expander 11, and a cold path of the first condenser 13 is communicated with the LNG pipeline. The exhaust gas of the first expander 11 is used to provide heat for LNG vaporization through the first condenser 13.
Further, the second branch further comprises a second condenser 9, a hot path inlet of the second condenser 9 is communicated with an air outlet of the second expander 7, and a cold path of the second condenser 9 is communicated with the LNG pipeline. The exhaust gas of the second expander is utilized to provide heat for LNG gasification through the second condenser.
Further, the cold path of the first condenser, the cold path of the second condenser and the cold path of the third condenser are all communicated with an LNG pipeline, a first cold quantity control valve 14 is arranged between the first condenser and the LNG pipeline, and a second cold quantity control valve 15 is arranged between the second condenser and the LNG pipeline; a third refrigeration control valve 16 is provided between the third condenser and the LNG line. The first, second and third refrigeration control valves 14, 15 and 16 are used to control LNG flows of the first, second and third condensers 13, 9 and 17, respectively.
Further, R410A is preferably used for the heating medium, and is liquid when it is at low temperature and low pressure, and after the cooling passage of the second vaporizer, the heating medium can be vaporized by using the temperature of the seawater (except for the winter), so as to meet the requirement of being introduced into the compressor.
Further, the first branch further comprises a first speed regulating valve 10, and the first speed regulating valve 10 is positioned at the inlet end of the first expander 11; and/or the second branch further comprises a second speed valve 6, said second speed valve 6 being located at the inlet end of said second expander 7. The flow rate of the power generation working medium flowing into the first expander 11 is controlled by the first speed regulating valve 10, and the first branch is connected and disconnected, and the flow rate of the power generation working medium flowing into the second expander 7 is controlled by the second speed regulating valve 6, and the second branch is connected and disconnected.
Further, the first branch further comprises a first check valve 12, and the first check valve 12 is located at the outlet end of the first expander 11; and/or said second branch further comprises a second non-return valve 8, said second non-return valve 8 being located at the outlet end of said second expander 7. The flow direction of the power generation working medium in the first expander 11 is from the inlet of the expander to the outlet of the expander, and the first check valve 12 is used for preventing the power generation working medium from flowing back in the first expander. The flow direction of the power generation working medium in the second expander 7 is from the inlet of the expander to the outlet of the expander, and the second check valve 8 is used for preventing the power generation working medium from flowing back in the second expander 7.
Further, the power generation working medium uses propane, and the heating working medium uses R410A. The gasification temperature of R410A is minus 51.6 ℃, when the heating working medium uses R410A, the heat path of the second vaporizer can be ensured to use seawater, and when the temperature of the seawater is lower, the heating working medium entering the compressor 20 can be ensured to be still in a gas phase, so that the compressor outlet can stably output the high-temperature heating working medium. The vaporization temperature of propane is 42.1 ℃ below zero, and the use of propane for the power generation working medium can ensure that R410A in the first vaporizer 4 can vaporize the power generation working medium, so that the power generation working medium at the inlet of the first expander and/or the second expander can be ensured to have higher temperature, and the power generation power is increased.
Embodiment two:
As shown in fig. 1, this embodiment provides an LNG receiving station, including any one of the LNG gasification systems for generating power using cold energy of the first embodiment, and further including a natural gas output pipeline. In the LNG gasification system for generating electricity by utilizing cold energy, the heat path of the second vaporizer of the heat circulation loop is connected with waste heat and waste heat, LNG is gasified by the LNG gasification system for generating electricity by utilizing cold energy of the embodiment, the downstream of the LNG pipeline is connected with a natural gas output pipeline, and gasified natural gas is connected with the natural gas output pipeline for downstream users.
Further, the heat path of the second vaporizer utilizes the heat source of the seawater. The heat source of seawater is an efficient and environmentally friendly energy source and the energy sources are quite extensive. Since the long-line natural gas is mostly transported by ship sea, the heat circuit of the second vaporizer can directly construct the LNG receiving station on the cargo ship, on the dock, or off-shore using the heat source of the seawater. And the LNG receiving station of the present embodiment can realize annual operation.
If the seawater heat source is sufficient and the temperature is high, the system can provide heat for gasifying LNG through the thermal circulation loop and the power generation circulation loop, and can generate power at the same time. When the residual heat source after the LNG gasification is insufficient for generating power, the first speed regulating valve 10 and the first cold quantity control valve 14 are closed, so that the power generation working medium circulates in the second branch only to provide heat for the LNG gasification.
In addition, the system also improves the power generation when the seawater heat source is sufficient and the temperature is higher. The outlet pressure of the circulating pump 3 is increased, so that the circulation volume of the power generation working medium can be increased, meanwhile, the opening degree of the second speed regulating valve 6 is reduced, the opening degree of the first speed regulating valve 10 is increased, the output work of the first expander 11 can be increased, and the power generation power is improved.
Further, the LNG gasification system for generating power by using cold energy of the LNG receiving station according to this embodiment includes a thermal circulation loop and a power generation circulation loop, wherein the thermal circulation loop includes a third condenser, and the power generation circulation loop includes a first branch and a second branch, wherein the first branch further includes the first condenser, and the second branch further includes the second condenser. The heat path inlet of the third condenser is communicated with the heat path outlet of the first evaporator, and the heat path temperature of the third condenser is the third temperature. The first condenser is located on a first branch of the power generation circulation loop, a first expander of the first branch is connected with the generator, power generation working medium subjected to temperature rise expands in the first expander to generate power, a hot path inlet of the first condenser is communicated with a gas outlet of the first expander, and the hot path temperature of the first condenser is at a first temperature. The second branch comprises a second expander, the warmed power generation working medium expands in the second expander to do work, and an output shaft of the second expander is connected with an input shaft of a compressor in the thermal circulation loop to provide power for the compressor in the thermal circulation loop. And the heat path inlet of the second condenser is communicated with the air outlet of the second expander, and the heat path temperature of the second condenser is the second temperature. Because the functions of the first expander and the second expander are different, the first expander is used for expansion power generation, the second expander uses expansion to do work, so that the outlet pressures of the first expander and the second expander are different, the temperatures of the first expander and the second expander are further different, and the principle of the expanders shows that the first temperature is lower than the second temperature. And the heat path inlet of the third condenser is communicated with the heat path outlet of the first evaporator, and the third temperature is higher than the first temperature and the second temperature.
Within the LNG receiving station, the LNG line is a transfer line for transferring liquefied natural gas, e.g. the LNG line may be led from a liquid cargo tank in an LNG cargo ship, the LNG line upstream of the LNG line being LNG to be gasified, from a source of liquefied natural gas, e.g. from the liquid cargo tank. As shown in fig. 1, LNG (liquefied natural gas) to be gasified is located upstream of the LNG line, and gasified natural gas is located downstream of the LNG line as an external pipeline for external use by a user via the downstream of the LNG line. The cold way of first condenser, the cold way of second condenser, the cold way of third condenser are parallelly connected respectively on the LNG pipeline, and the cold way export of first condenser is connected in the cold way export of second condenser's the upper reaches, and the cold way export of second condenser is connected in the cold way export of third condenser's the upper reaches, guarantees that the third temperature is higher than the second temperature, and the second temperature is higher than first temperature, and then guarantees that the gasification temperature of LNG rises gradually, has guaranteed the operation of system safety and stability.
Therefore, compared with the prior art, the LNG receiving station provided by the embodiment has at least the following advantages: ① When the seawater heat source is sufficient, the utilization rate of the seawater heat source can be improved, and the power generation load of the system can be adjusted, so that the whole system has higher controllability. ② The LNG gasification system for generating electricity by utilizing cold energy is provided with a second branch, and the second expansion machine is used for driving the compressor, so that compared with the prior art, the LNG gasification system has higher energy efficiency ratio. ③ When the heat source of the seawater is insufficient, the system can still be used for providing heat for the gasification of the LNG in the conveying pipeline, and compared with the prior art, the fuel consumption required by the LNG gasification is further reduced. ④ The system improves the annual utilization rate of LNG cold energy.
It is to be understood that the above examples of the present invention are provided for clarity of illustration only and are not limiting of the embodiments of the present invention. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. Any modification, equivalent replacement, improvement, etc. which come within the spirit and principles of the invention are desired to be protected by the following claims.

Claims (10)

1. An LNG gasification system for generating electricity by utilizing cold energy is characterized by comprising a thermal circulation loop and a power generation circulation loop;
The internal circulation of the thermal circulation loop is provided with a heating working medium, and the thermal circulation loop comprises a compressor, a first evaporator, a third condenser, an expansion valve and a second evaporator; the heating working medium flows into the hot path inlet of the first vaporizer through the outlet of the compressor, flows out of the hot path outlet of the first vaporizer and then enters the hot path inlet of the third condenser, flows out of the hot path outlet of the third condenser and then enters the inlet of the expansion valve, flows out of the outlet of the expansion valve and then enters the cold path inlet of the second vaporizer, flows out of the cold path outlet of the second vaporizer and then returns to the compressor; the cold path of the third condenser is communicated with an LNG pipeline;
The power generation circulation loop internally circulates a power generation working medium and comprises a cold path, a first branch and a second branch of the first vaporizer; the power generation working medium flows out from a cold path outlet of the first vaporizer and then enters the first branch and the second branch respectively; the first branch comprises a first expander, and the first expander is connected with a generator; the second branch comprises a second expander, and an output shaft of the second expander is connected with an input shaft of the compressor.
2. The LNG vaporization system utilizing cold energy for power generation according to claim 1, wherein the power generation circulation loop further comprises a storage tank and a buffer tank; the storage tank is used for storing low-temperature and low-pressure power generation working media, and the buffer tank is used for storing high-temperature and high-pressure power generation working media;
The power generation working medium flowing out of the storage tank enters the cold path inlet of the first vaporizer, flows out of the cold path outlet of the first vaporizer and enters the buffer tank, and flows out of the outlet of the buffer tank and then enters the first branch and the second branch respectively.
3. The LNG vaporization system utilizing cold energy for generating electricity according to claim 2, wherein the power generation circulation loop further comprises a circulation pump, a first control valve, an outlet of the storage tank being in communication with an inlet of the circulation pump, an outlet of the circulation pump being in communication with a cold path inlet of the first vaporizer; the first control valve is located on a line between the outlet of the reservoir and the inlet of the circulation pump.
4. The LNG vaporization system of claim 1, wherein the first leg further comprises a first condenser, a hot leg inlet of the first condenser is in communication with an air outlet of the first expander, and a cold leg of the first condenser is in communication with an LNG line.
5. The LNG vaporization system of claim 1, wherein the second leg further comprises a second condenser, a hot leg inlet of the second condenser in communication with an air outlet of the second expander, a cold leg of the second condenser in communication with an LNG line.
6. The LNG gasification system for generating electricity using cold energy of claim 1, wherein the first leg further comprises a first speed valve located at an inlet end of the first expander; and/or, the second branch further comprises a second speed regulating valve, and the second speed regulating valve is positioned at the inlet end of the second expander.
7. The LNG vaporization system utilizing cold energy for generating electricity of claim 1, wherein the first leg further comprises a first check valve located at an outlet end of the first expander; and/or the second branch further comprises a second check valve, and the second check valve is positioned at the outlet end of the second expander.
8. The LNG vaporization system using cold energy for power generation according to claim 1, wherein the power generation working medium uses propane and the heating working medium uses R410A.
9. An LNG receiving station, characterized by comprising the LNG gasification system using cold energy to generate electricity according to any one of claims 1-8 and a natural gas output pipeline, wherein the heat path of the second vaporizer is connected with waste heat and waste heat, and the downstream of the LNG pipeline is connected with the natural gas output pipeline.
10. The LNG receiving station of claim 9, wherein the thermal cycle loop comprises the third condenser; the first branch of the power generation cycle loop further comprises a first condenser, and the second branch further comprises a second condenser;
The cold path of the first condenser, the cold path of the second condenser and the cold path of the third condenser are respectively connected in parallel to the LNG pipeline; the cold path outlet of the first condenser is connected with the upstream of the cold path outlet of the second condenser, and the cold path outlet of the second condenser is connected with the upstream of the cold path outlet of the third condenser.
CN202410250713.7A 2024-03-05 2024-03-05 LNG gasification system for generating power by utilizing cold energy and LNG receiving station Pending CN117889349A (en)

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