CN112177698A - Liquefied natural gas cold energy power generation device - Google Patents
Liquefied natural gas cold energy power generation device Download PDFInfo
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- CN112177698A CN112177698A CN202011188164.3A CN202011188164A CN112177698A CN 112177698 A CN112177698 A CN 112177698A CN 202011188164 A CN202011188164 A CN 202011188164A CN 112177698 A CN112177698 A CN 112177698A
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- cold energy
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- 239000003949 liquefied natural gas Substances 0.000 title claims abstract description 144
- 238000010248 power generation Methods 0.000 title claims abstract description 116
- 238000003303 reheating Methods 0.000 claims abstract description 115
- 239000007791 liquid phase Substances 0.000 claims abstract description 81
- 238000010438 heat treatment Methods 0.000 claims abstract description 17
- 239000007789 gas Substances 0.000 claims description 70
- 239000012071 phase Substances 0.000 claims description 54
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 48
- 239000003345 natural gas Substances 0.000 claims description 24
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 16
- 238000002485 combustion reaction Methods 0.000 claims description 14
- 239000002737 fuel gas Substances 0.000 claims description 12
- 230000005611 electricity Effects 0.000 claims description 5
- 230000008878 coupling Effects 0.000 claims description 3
- 238000010168 coupling process Methods 0.000 claims description 3
- 238000005859 coupling reaction Methods 0.000 claims description 3
- 238000000034 method Methods 0.000 abstract description 10
- 238000002309 gasification Methods 0.000 abstract description 5
- 230000000694 effects Effects 0.000 abstract description 4
- 230000007613 environmental effect Effects 0.000 abstract description 4
- 230000010354 integration Effects 0.000 abstract description 3
- 239000013535 sea water Substances 0.000 description 18
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 description 14
- 239000007788 liquid Substances 0.000 description 7
- 239000001294 propane Substances 0.000 description 7
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 5
- 239000003546 flue gas Substances 0.000 description 5
- 229910001220 stainless steel Inorganic materials 0.000 description 5
- 239000010935 stainless steel Substances 0.000 description 5
- 230000005540 biological transmission Effects 0.000 description 4
- 230000009286 beneficial effect Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000000567 combustion gas Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 238000009834 vaporization Methods 0.000 description 1
- 230000008016 vaporization Effects 0.000 description 1
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
- F01K25/00—Plants or engines characterised by use of special working fluids, not otherwise provided for; Plants operating in closed cycles and not otherwise provided for
- F01K25/08—Plants or engines characterised by use of special working fluids, not otherwise provided for; Plants operating in closed cycles and not otherwise provided for using special vapours
- F01K25/10—Plants or engines characterised by use of special working fluids, not otherwise provided for; Plants operating in closed cycles and not otherwise provided for using special vapours the vapours being cold, e.g. ammonia, carbon dioxide, ether
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D15/00—Adaptations of machines or engines for special use; Combinations of engines with devices driven thereby
- F01D15/10—Adaptations for driving, or combinations with, electric generators
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Engine Equipment That Uses Special Cycles (AREA)
Abstract
The invention discloses a liquefied natural gas cold energy power generation device, which aims to solve the problems that in the prior art, the liquefied natural gas cold energy power generation device is influenced by the temperature factor of a reheating medium in winter, so that the power generation amount is low, and even the liquefied natural gas cold energy power generation device cannot normally operate; the LNG liquid phase pipe is used for introducing LNG in a liquid phase state to the Rankine cycle power generation unit for heat exchange; the reheating unit is loaded with a reheating medium and an auxiliary heating unit, and the reheating unit gradually extends to the position near the bottom in the reheating unit from the outside of the reheating unit to heat the reheating medium. The invention provides a liquefied natural gas cold energy power generation device, which utilizes an auxiliary heating unit to heat a reheating medium so as to compensate the effect of reheating a working medium when the temperature of the reheating medium is lower than 5-10 ℃ in winter, has high integration level, is not influenced by external environmental factors, efficiently recovers cold energy in an LNG gasification process, and can ensure continuous and stable operation of LNG cold energy power generation all the year round.
Description
Technical Field
The invention belongs to the technical field of liquefied natural gas cold energy utilization, and particularly relates to a liquefied natural gas cold energy power generation device.
Background
Liquefied Natural Gas (LNG) is a high-efficiency clean energy source. At present, more than 20 large coastal LNG receiving stations are put into operation in China, and more than 40 large built or proposed LNG receiving stations are put into operation. In a large-scale coastal LNG receiving station, in order to meet the conveying requirement of a natural gas pipeline network, LNG needs to be pressurized and gasified into normal-temperature gas by a high-pressure pump and then is sent into the natural gas pipeline network. During LNG vaporization, LNG releases a large amount of cold energy. The cold energy released in the LNG gasification process is recycled, so that the energy utilization efficiency is improved, and the policy requirements of energy conservation, emission reduction and development of low-carbon economy advocated by the state are met.
The performance of LNG cold energy power generation is closely related to external environmental factors, and particularly in large-scale coastal LNG receiving stations, low-temperature Rankine cycle power generation is generally adopted. In the power generation process, the low-temperature natural gas and the circulating working medium generally adopt seawater as a heat source for reheating so as to meet the requirement of natural gas output temperature, and simultaneously the circulating working medium is gasified so as to enter a power generation expansion machine for expansion. In winter, the temperature of seawater is low, so that the low-temperature natural gas reheating requirement cannot be met, and meanwhile, the temperature of the circulating working medium entering the expansion generator is low, so that the power generation capacity of the expansion generator is low. Therefore, when the temperature of the seawater is lower than 5-10 ℃ in winter, the cold energy power generation device of the large LNG receiving station has the problems of low power generation capacity and even incapability of normal operation, and great influence is brought to the operation of the cold energy power generation device.
Disclosure of Invention
The invention provides a liquefied natural gas cold energy power generation device, aiming at overcoming the problems that the power generation capacity is low and even the liquefied natural gas cold energy power generation device cannot normally operate due to the influence of the temperature factor of a reheating medium in winter, the liquefied natural gas cold energy power generation device utilizes an auxiliary heating unit to heat the reheating medium so as to make up the reheating effect on a working medium when the temperature of the reheating medium is lower than 5-10 ℃ in winter, the integration level is high, the influence of external environmental factors is avoided, the cold energy in the LNG gasification process is efficiently recovered, and the continuous and stable operation of LNG cold energy power generation all the year around can be ensured.
The technical scheme adopted by the invention is as follows:
a liquefied natural gas cold energy power generation device comprises
The Rankine cycle power generation unit is loaded with working media; the working medium in the liquid phase state is pressurized and then changed into a high-pressure liquid phase, and after the high-pressure liquid phase is reheated to be in a gas phase state, the volume expansion externally applies work and generates electricity;
the LNG liquid phase pipe is used for introducing LNG in a liquid phase state to the Rankine cycle power generation unit and exchanging heat with working media in a low-pressure gas phase state in the Rankine cycle power generation unit;
the reheating unit is loaded with reheating media and is used for reheating the working medium in a low-temperature liquid phase state to the working medium in an overheated high-temperature gas phase state; and
and the auxiliary heating unit gradually extends from the outside of the reheating unit to the position near the bottom in the reheating unit to heat the reheating medium.
In one embodiment of the present disclosure, the Rankine cycle power generation unit includes
An expansion generator set;
the first heat exchanger is provided with a first heat exchange channel and a second heat exchange channel which are independent;
a working medium booster pump;
the second heat exchanger is immersed in the reheating medium of the reheating unit;
the two ends of the first pipeline are respectively connected with the outlet end of the expansion generator set and the inlet end of the second heat exchange channel of the first heat exchanger;
two ends of the second pipeline are respectively connected with the outlet end of the second heat exchange channel of the first heat exchanger and the inlet end of the working medium booster pump;
two ends of the third pipeline are respectively connected with the outlet end of the working medium booster pump and the inlet end of the second heat exchanger; and the number of the first and second groups,
two ends of the fourth pipeline are respectively connected with the outlet end of the second heat exchanger and the inlet end of the expansion generator set;
wherein, the LNG liquid phase pipe is communicated with the first heat exchange channel of the first heat exchanger.
In one embodiment of the present disclosure, the reheating unit comprises
The pool is a closed structure and is filled with reheating media;
and the exhaust port is connected with the top of the water pool.
In one embodiment of the present disclosure, the secondary thermal unit includes
A burner having a combustion chamber; the combustion chamber gradually extends from the outside of the reheating unit to the vicinity of the bottom in the reheating unit;
a fan;
a fuel gas pipe connected with the burner; and
and the two ends of the air pipe are respectively connected with the combustor and the fan.
In one embodiment of the present disclosure, the plant further comprises an LNG supply unit.
In one embodiment of the present disclosure, the LNG supply unit includes
The third heat exchanger is immersed in the reheating medium of the reheating unit;
the two ends of the fifth pipeline are respectively connected with the outlet end of the first heat exchange channel of the first heat exchanger and the inlet end of the third heat exchanger; and
two ends of the sixth pipeline are respectively connected with the outlet end of the third heat exchanger and the gas supply pipe network;
wherein the LNG liquid phase pipe is connected with the inlet end of the first heat exchange channel of the first heat exchanger.
In one embodiment of the present disclosure, the second heat exchanger and the third heat exchanger employ integrated coupled heat exchangers; the coupling heat exchanger is provided with a first channel, a second channel and a third channel; working media flow in the first channel; natural gas flows in the second channel; the first channel and the second channel are positioned in the third channel, and a complex heat medium flows in the first channel and the second channel.
In an embodiment disclosed in the present application, the LNG gas supply unit further includes a bypass valve, and two ends of the bypass valve are respectively connected to the LNG liquid phase and the fifth pipeline.
The invention has the beneficial effects that:
the invention provides a liquefied natural gas cold energy power generation device, which aims to solve the problems that the power generation capacity of a cold energy power generation device is low and even the cold energy power generation device cannot normally operate due to the influence of a reheat heat source on a large LNG receiving station in winter. The device comprises a Rankine cycle power generation unit, an LNG liquid phase pipe, a reheating unit and an auxiliary heating unit. The Rankine cycle power generation unit is internally loaded with working media such as propane and the like, and flows in an internal circulation mode. When the working medium expands from a high-pressure gas phase state to a low-pressure gas phase state, the volume expands to apply work outwards, and therefore power generation is achieved. And the LNG liquid phase pipe is used for introducing LNG in a liquid phase state to the Rankine cycle power generation unit and exchanging heat with working medium in a low-pressure gas phase state in the Rankine cycle power generation unit. And cooling the working medium in a low-pressure gas phase state into the working medium in a low-temperature liquid phase state by using the low temperature of the liquid-phase LNG flowing in the LNG liquid phase pipe. The reheating unit is filled with reheating media such as water, a circulation passage of the working medium in a low-temperature liquid phase state is immersed in the reheating media, and the supercharged working medium in a high-pressure low-temperature liquid phase state is reheated to the overheated working medium in a high-temperature gas phase state. And the auxiliary heating unit gradually extends from the outside of the reheating unit to the position near the bottom in the reheating unit to heat the reheating medium, so that the effect of reheating the working medium when the temperature of the reheating medium is lower than 5-10 ℃ in winter is compensated. The liquefied natural gas cold energy power generation device has high integration level, is not influenced by external environmental factors, and can ensure the continuous and stable operation of LNG cold energy power generation all the year round.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative efforts.
Fig. 1 is a schematic view of a connection structure of a lng cold energy power generation apparatus according to embodiment 1.
Fig. 2 is a schematic view of a connection structure of the lng cold energy power generation apparatus according to embodiment 2.
Fig. 3 is a schematic view of a connection structure of the lng cold energy power generation apparatus according to embodiment 3.
Detailed Description
In the following, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.
In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and are not to be considered limiting of the invention.
The following disclosure provides many different embodiments or examples for implementing different features of the invention. To simplify the disclosure of the present invention, the components and arrangements of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention.
The following describes in detail embodiments of the present invention with reference to the accompanying drawings.
Example 1
In the LNG cold energy power generation process, the circulating working medium generally adopts seawater as a heat source for reheating, so that the circulating working medium is gasified to enter a power generation expansion machine for expansion. In winter, the temperature of seawater is low, so that the reheating requirement cannot be met, and meanwhile, the temperature of the circulating working medium entering the expansion generator is low, so that the generating capacity of the expansion generator is low. Therefore, when the temperature of the seawater is lower than 5-10 ℃ in winter, the cold energy power generation device of the large LNG receiving station has the problems of low power generation capacity and even incapability of normal operation, and great influence is brought to the operation of the cold energy power generation device.
In order to solve the problem that the power generation capacity of a cold energy power generation device is low or even the cold energy power generation device cannot normally operate due to the influence of a reheat heat source on a large LNG receiving station in winter, the invention provides a liquefied natural gas cold energy power generation device, which is structurally shown in an attached drawing 1. The device comprises a Rankine cycle power generation unit 1, an LNG liquid phase pipe 2, a reheating unit 3 and an auxiliary heating unit 4. The Rankine cycle power generation unit 1 is internally loaded with working media such as propane and the like, and flows in an internal circulation mode. When the working medium expands from a high-pressure gas phase state to a low-pressure gas phase state, the volume expands to apply work outwards, and therefore power generation is achieved. The LNG liquid phase pipe 2 is used for introducing LNG in a liquid phase state to the Rankine cycle power generation unit 1 and exchanging heat with working media in a low-pressure gas phase state in the Rankine cycle power generation unit 1. The working medium in the gas phase state is cooled into the working medium in the low-temperature liquid phase state by utilizing the low temperature of the liquid-phase LNG flowing in the LNG liquid phase pipe 2. The reheating unit 3 is filled with reheating media such as water, a circulation passage of the working medium in a low-temperature liquid phase state is immersed in the reheating media, and the pressurized working medium in a high-pressure low-temperature liquid phase state is reheated to the working medium in an overheated high-temperature gas phase state. And the auxiliary heating unit 4 gradually extends from the outside of the reheating unit to the vicinity of the bottom in the reheating unit to heat the reheating medium. Adopt the liquefied natural gas cold energy power generation facility in this embodiment, the integrated level is high, does not receive external environment factor to influence, can guarantee that LNG cold energy power generation moves steadily all the year round.
Specifically, the Rankine cycle power generation unit 1 comprises an expansion generator set 11, a first heat exchanger 12, a working medium booster pump 13 and a second heat exchanger 14.
The first heat exchanger 12 is a stainless steel U-shaped heat exchanger, and has a first heat exchange channel 121 and a second heat exchange channel 122 which are independent. The LNG liquid phase pipe 2 is connected to the inlet end of the first heat exchange path 121. The expansion generator set 11 is composed of a radial turbo expander, a generator and the like, and the outlet end of the expansion generator set is connected with the inlet end of the second heat exchange channel 122 through the first pipeline 15. The working medium booster pump 13 adopts a barrel-type immersed pump, and the inlet end of the barrel-type immersed pump is connected with the outlet end of the second heat exchange channel 122 through a second pipeline 16. The outlet end of the working medium booster pump 13 is connected with the inlet end of the second heat exchanger 14 through a third pipeline 17. The outlet end of the second heat exchanger 14 and the inlet end of the expansion generator set 11 are connected by a fourth pipe 18. The second heat exchanger 14 is immersed in the reheating medium.
When the working medium in the gas phase state and the LNG in the liquid phase state flow in the first heat exchange channel 121 and the second heat exchange channel 122, respectively, heat exchange is performed, and the working medium in the gas phase state is cooled to become the working medium in the low temperature liquid phase state. When the working medium in the high-pressure low-temperature liquid phase state flows through the second heat exchanger 14, the working medium is converted into the working medium in the superheated high-temperature high-pressure gas phase state. When the working medium in the superheated high-temperature high-pressure gas phase state passes through the expansion generator set 11, the volume expands, so that the expansion generator set 11 does work outwards to generate electricity.
The reheating unit 3 includes a water tank 31 and an exhaust port 32.
The water pool 31 is of a closed structure and is filled with reheating media such as seawater. The reheating medium level needs to be submerged in the second heat exchanger 14. The exhaust port 32 communicates with the top of the sump 31. The liquid level of the reheating medium in the water tank 31 is set according to the requirement and is supplemented in time so as to maintain the liquid level.
The auxiliary heating unit 4 includes a fan 41, a burner 42, and a fuel gas pipe 43.
The blower 31 is connected to the burner 42 via an air duct 44. The fuel gas pipe 43 is also connected to the burner 42. The combustion chamber 421 of the burner 42 is gradually submerged into the sump 31 and extends below the second heat exchanger 14. After the fuel gas is combusted, the generated high-temperature flue gas overflows from the combustion chamber 421, and then is contacted and mixed with the reheating medium to heat the reheating medium.
In this embodiment, the principle of the lng cold energy power generation apparatus is as follows:
the high pressure LNG enters the first heat exchanger 12 to transfer cold energy to the working medium in a gas phase state, so that the working medium is cooled to a working medium in a low temperature liquid phase state. The working medium in the low-temperature liquid phase state enters a working medium booster pump 13 to be boosted, and the working medium in the high-pressure low-temperature liquid phase state enters a second heat exchanger 14 after being boosted. In the reheating unit 3, the second heat exchanger 14 exchanges heat, and the working medium in the high-pressure low-temperature liquid phase state is heated and gasified to the high-pressure gas phase state, and then enters the expansion generator set 11. The volume of the working medium expands, in the expansion process, the expander drives the generator to do work outwards, so that the LNG cold energy is converted into electric energy, the expanded working medium in the low-pressure gas phase state enters the first heat exchanger 12 again, and a cycle is completed.
The heat required when the working medium in the high-pressure low-temperature liquid phase state is heated and gasified to the high-pressure superheated gas phase state is provided by the reheating medium in the reheating unit 3.
The large LNG receiving station adopts high-pressure LNG with the pressure of 9.5MPa and the temperature of-145 ℃, the temperature of seawater in winter is 5 ℃, and the circulating working medium adopts propane. Under the working condition, the power generation amount of each ton of LNG is about 19 KW. By adopting the device, the LNG cold energy can be efficiently utilized, and the stable power generation state throughout the year can be maintained.
Example 2
In the LNG cold energy power generation process, the low-temperature natural gas and the circulating working medium generally adopt seawater as a heat source for reheating so as to meet the requirement of natural gas output temperature, and the circulating working medium is gasified so as to enter a power generation expansion machine for expansion. In winter, the temperature of seawater is low, so that the low-temperature natural gas reheating requirement cannot be met, and meanwhile, the temperature of the circulating working medium entering the expansion generator is low, so that the power generation capacity of the expansion generator is low. Therefore, when the temperature of the seawater is lower than 5-10 ℃ in winter, the cold energy power generation device of the large LNG receiving station has the problems of low power generation capacity and even incapability of normal operation, and great influence is brought to the operation of the cold energy power generation device.
In order to solve the problems that the power generation capacity of a cold energy power generation device is low and even the cold energy power generation device cannot normally operate due to the influence of a complex heat source on a large LNG receiving station in winter and the requirement on the temperature of the natural gas output cannot be met, the invention provides a liquefied natural gas cold energy power generation device which is shown in an attached figure 2. The device comprises a Rankine cycle power generation unit 1, an LNG liquid phase pipe 2, a reheating unit 3, an auxiliary heating unit 4 and an LNG gas supply unit 5. The Rankine cycle power generation unit 1 is internally loaded with working media such as propane and the like, and flows in an internal circulation mode. When the working medium expands from a high-pressure gas phase state to a low-pressure gas phase state, the volume expands to apply work outwards, and therefore power generation is achieved. The LNG liquid phase pipe 2 is used for introducing LNG in a liquid phase state to the Rankine cycle power generation unit 1 and exchanging heat with the working medium in a gas phase state in the Rankine cycle power generation unit 1. The working medium in the gas phase state is cooled into the working medium in the low-temperature liquid phase state by utilizing the low temperature of the liquid-phase LNG flowing in the LNG liquid phase pipe 2. The reheating unit 3 is filled with reheating media such as water, a flow passage of a pressurized working medium in a high-pressure low-temperature liquid phase state is immersed in the reheating media, and a flow passage of low-temperature natural gas in a gas phase state is immersed in the reheating media, so that the working medium in the high-pressure low-temperature liquid phase state is gasified into the working medium in a high-pressure superheated gas phase state. And the auxiliary heating unit 4 gradually extends from the outside of the reheating unit to the vicinity of the bottom in the reheating unit to heat the reheating medium. And the LNG gas supply unit 5 is used for rewarming the low-temperature natural gas to the temperature required by the external transmission pipeline network and then entering the gas supply pipeline network.
Adopt the liquefied natural gas cold energy power generation facility in this embodiment, the integrated level is high, does not receive external environment factor to influence, can guarantee that LNG cold energy power generation moves steadily all the year round. Meanwhile, the liquefied natural gas cold energy power generation device in the embodiment has power generation and gasification functions, namely LNG cold energy is fully utilized, LNG gas supply is realized, and the function is more extensive.
Specifically, the Rankine cycle power generation unit 1 comprises an expansion generator set 11, a first heat exchanger 12, a working medium booster pump 13 and a second heat exchanger 14.
The first heat exchanger 12 is a stainless steel U-shaped heat exchanger, and has a first heat exchange channel 121 and a second heat exchange channel 122 which are independent. The LNG liquid phase pipe 2 is connected to the inlet end of the first heat exchange path 121. The outlet end of the first heat exchange channel 121 is connected to the LNG feed unit. The expansion generator set 11 is composed of a radial turbo expander, a generator and the like, and the outlet end of the expansion generator set is connected with the inlet end of the second heat exchange channel 122 through the first pipeline 15. The working medium booster pump 13 adopts a barrel-type immersed pump, and the inlet end of the barrel-type immersed pump is connected with the outlet end of the second heat exchange channel 122 through a second pipeline 16. The outlet end of the working medium booster pump 13 is connected with the inlet end of the second heat exchanger 14 through a third pipeline 17. The outlet end of the second heat exchanger 14 and the inlet end of the expansion generator set 11 are connected by a fourth pipe 18. The second heat exchanger 14 is immersed in the reheating medium.
When the working medium in the gas phase state and the LNG in the liquid phase state flow in the first heat exchange channel 121 and the second heat exchange channel 122, respectively, heat exchange is performed, and the working medium in the gas phase state is cooled to become the working medium in the low temperature liquid phase state. When the working medium in the high-pressure low-temperature liquid phase state flows through the second heat exchanger 14, the working medium is converted into the working medium in the high-pressure superheated gas phase state. When the high-pressure gas-phase working medium passes through the expansion generator set 11, the volume is expanded, so that the expansion generator set 11 does work outwards to generate electricity.
The reheating unit 3 includes a water tank 31 and an exhaust port 32.
The water pool 31 is of a closed structure and is filled with reheating media such as seawater. The second heat exchanger 14 needs to be submerged at the liquid level of the reheating medium. The exhaust port 32 communicates with the top of the sump 31. The liquid level of the reheating medium in the water tank 31 is set according to the requirement and is supplemented in time so as to maintain the liquid level.
The auxiliary heating unit 4 includes a fan 41, a burner 42, and a fuel gas pipe 43.
The blower 31 is connected to the burner 42 via an air duct 44. The fuel gas pipe 43 is also connected to the burner 42. The combustion chamber 421 of the burner 42 is gradually submerged into the sump 31 and extends below the second heat exchanger 14. After the fuel gas is combusted, the generated high-temperature flue gas overflows from the combustion chamber 421, and then is contacted and mixed with the reheating medium to heat the reheating medium.
The LNG supply unit 5 includes a third heat exchanger 51.
The third heat exchanger 51 is immersed in the reheating medium and is located above the second heat exchanger 14 and simultaneously above the position of the outlet of the combustion chamber 421. The inlet end of the third heat exchanger 51 is connected to the outlet end of the first heat exchange channel 121 via a fifth conduit 52. The inlet end of the third heat exchanger 51 is connected to the supply network via a sixth conduit 53.
The natural gas in the low-temperature state enters the gas supply pipe network after being reheated to the temperature required by the external transmission pipe network.
In this embodiment, the second ventilator 14 and the third heat exchanger 51 are integrated coupled heat exchangers such as stainless steel serpentine heat exchange tube heat exchangers having a first channel, a second channel, and a third channel. Working medium flows in the first channel, and low-temperature natural gas flows in the second channel. The first channel and the second channel are positioned in the third channel, and a complex heat medium flows in the third channel.
In this embodiment, the principle of the lng cold energy power generation apparatus is as follows:
the high pressure LNG enters the first heat exchanger 12 to transfer cold energy to the working medium in a gas phase state, so that the working medium is cooled to a working medium in a low temperature liquid phase state. The working medium in the low-temperature liquid phase state enters a working medium booster pump 13 to be boosted, and the working medium in the low-temperature liquid phase state after being boosted enters a second heat exchanger 14. In the reheating unit 3, the second heat exchanger 14 exchanges heat, and the working medium in the high-pressure low-temperature liquid phase state is gasified into a high-pressure superheated gas phase state and then enters the expansion generator set 11. The volume of the working medium expands, in the expansion process, the expander drives the generator to do work outwards, so that the LNG cold energy is converted into electric energy, the expanded working medium in a gas phase state enters the first heat exchanger 12 again, and a cycle is completed.
The LNG exchanges heat in the first heat exchanger 12, then enters the third heat exchanger 51, and enters the gas supply pipe network after being reheated to the temperature required by the external pipeline network.
The heat required when the working medium in the low-temperature liquid phase state is gasified and heated to the superheated gas phase state and the heat required by LNG rewarming are provided by the rewarming medium in the rewarming unit 3.
High-temperature flue gas generated by combustion of the fuel gas and air in the combustor is brought into the water pool 31 to heat the reheating medium.
The large LNG receiving station is high-pressure LNG with the pressure of 9.5MPa and the temperature of-145 ℃, the temperature of seawater in winter is 5 ℃, and the circulating working medium is propane. Under the working condition, the power generation amount of each ton of LNG is about 19 KW, and the liquefied natural gas can be reheated to normal temperature. By adopting the device, the LNG cold energy can be efficiently utilized, and the stable power generation state throughout the year can be maintained.
Example 3
In the LNG cold energy power generation process, the low-temperature natural gas and the circulating working medium generally adopt seawater as a heat source for reheating so as to meet the requirement of natural gas output temperature, and the circulating working medium is gasified so as to enter a power generation expansion machine for expansion. In winter, the temperature of seawater is low, so that the low-temperature natural gas reheating requirement cannot be met, and meanwhile, the temperature of the circulating working medium entering the expansion generator is low, so that the power generation capacity of the expansion generator is low. Therefore, when the temperature of the seawater is lower than 5-10 ℃ in winter, the cold energy power generation device of the large LNG receiving station has the problems of low power generation capacity and even incapability of normal operation, and great influence is brought to the operation of the cold energy power generation device.
In order to solve the problems that the power generation capacity of a cold energy power generation device is low and even the cold energy power generation device cannot normally operate due to the influence of a complex heat source on a large LNG receiving station in winter and the requirement on the temperature of the natural gas output cannot be met, the invention provides a liquefied natural gas cold energy power generation device which is shown in an attached drawing 3. The device comprises a Rankine cycle power generation unit 1, an LNG liquid phase pipe 2, a reheating unit 3, an auxiliary heating unit 4 and an LNG gas supply unit 5. The Rankine cycle power generation unit 1 is internally loaded with working media such as propane and the like, and flows in an internal circulation mode. When the working medium expands from a high-pressure gas phase state to a low-pressure gas phase state, the volume expands to apply work outwards, and therefore power generation is achieved. The LNG liquid phase pipe 2 is used for introducing LNG in a liquid phase state to the Rankine cycle power generation unit 1 and exchanging heat with the working medium in a gas phase state in the Rankine cycle power generation unit 1. The working medium in the gas phase state is cooled into the working medium in the low-temperature liquid phase state by utilizing the low temperature of the liquid-phase LNG flowing in the LNG liquid phase pipe 2. The reheating unit 3 is filled with reheating media such as water, a flow passage of working media in a low-temperature liquid phase state is immersed in the reheating media, and a flow passage of natural gas in a low-temperature gas phase is immersed in the reheating media, so that the working media in the low-temperature liquid phase state are gasified to the working media in a superheated gas phase state. And the auxiliary heating unit 4 gradually extends from the outside of the reheating unit to the position near the bottom in the reheating unit to heat the reheating medium, so that the reheating effect on the working medium is compensated when the temperature of the reheating medium is lower than 5-10 ℃ in winter. And the LNG gas supply unit 5 is reheated to the temperature required by the external transmission pipe network and then enters the gas supply pipe network.
Adopt the liquefied natural gas cold energy power generation facility in this embodiment, the integrated level is high, does not receive external environment factor to influence, can guarantee that LNG cold energy power generation moves steadily all the year round. Meanwhile, the lng cold energy power generation apparatus in this embodiment may be switched between a power generation mode and a gas supply mode.
Specifically, the Rankine cycle power generation unit 1 comprises an expansion generator set 11, a first heat exchanger 12, a working medium booster pump 13 and a second heat exchanger 14.
The first heat exchanger 12 is a stainless steel U-shaped heat exchanger, and has a first heat exchange channel 121 and a second heat exchange channel 122 which are independent. The LNG liquid phase pipe 2 is connected to the inlet end of the first heat exchange path 121. The outlet end of the first heat exchange channel 121 is connected to the LNG feed unit. The expansion generator set 11 is composed of a radial turbo expander, a generator and the like, and the outlet end of the expansion generator set is connected with the inlet end of the second heat exchange channel 122 through the first pipeline 15. The working medium booster pump 13 adopts a barrel-type immersed pump, and the inlet end of the barrel-type immersed pump is connected with the outlet end of the second heat exchange channel 122 through a second pipeline 16. The outlet end of the working medium booster pump 13 is connected with the inlet end of the second heat exchanger 14 through a third pipeline 17. The outlet end of the second heat exchanger 14 and the inlet end of the expansion generator set 11 are connected by a fourth pipe 18. The second heat exchanger 14 is immersed in the reheating medium.
When the working medium in the gas phase state and the LNG in the liquid phase state flow in the first heat exchange channel 121 and the second heat exchange channel 122, respectively, heat exchange is performed, and the working medium in the gas phase state is cooled to become the working medium in the low temperature liquid phase state. When the working medium in the high-pressure low-temperature liquid phase state flows through the second heat exchanger 14, the working medium is converted into the working medium in the high-pressure superheated gas phase state. When the working medium in the high-pressure superheated gas phase state passes through the expansion generator set 11, the high-pressure superheated gas phase state is converted into the working medium in the low-pressure gas phase state, and the volume is expanded, so that the expansion generator set 11 does work outwards to generate electricity. And after heat exchange, the liquid-phase LNG is heated, and enters an air supply pipe network after further reheating.
The reheating unit 3 includes a water tank 31 and an exhaust port 32.
The water pool 31 is of a closed structure and is filled with reheating media such as seawater. The reheating medium level needs to be higher than the second heat exchanger 14. The exhaust port 32 communicates with the top of the sump 31. The liquid level of the reheating medium in the water tank 31 is set according to the requirement and is supplemented in time so as to maintain the liquid level.
The auxiliary heating unit 4 includes a fan 41, a burner 42, and a fuel gas pipe 43.
The blower 31 is connected to the burner 42 via an air duct 44. The fuel gas pipe 43 is also connected to the burner 42. The combustion chamber 421 of the burner 42 is gradually submerged into the sump 31 and extends below the second heat exchanger 14. After the fuel gas is combusted, the generated high-temperature flue gas overflows from the combustion chamber 421 and contacts and mixes with the reheating medium to heat the reheating medium
The LNG supply unit 5 includes a third heat exchanger 51 and a bypass valve 54.
The third heat exchanger 51 is immersed in the reheating medium and is located above the second heat exchanger 14 and simultaneously above the position of the outlet of the combustion chamber 421. The inlet end of the third heat exchanger 51 is connected to the outlet end of the first heat exchange channel 121 via a fifth conduit 52. The inlet end of the third heat exchanger 51 is connected to the supply network via a sixth conduit 53. The natural gas in the low-temperature gas phase state enters the gas supply pipe network after being reheated to the temperature required by the external transmission pipe network. The bypass valve 54 is disposed outside the first heat exchanger 12, and both ends of the bypass valve are connected to the LNG liquid phase pipe 2 and the fifth pipeline 52, respectively. The rankine cycle power generation unit 1 is closed, the bypass valve 54 is opened, and only the air supply operation can be performed.
In this embodiment, the second ventilator 14 and the third heat exchanger 51 are integrated coupled heat exchangers such as stainless steel serpentine heat exchange tube heat exchangers having a first channel, a second channel, and a third channel. Working medium flows in the first channel, and low-temperature natural gas flows in the second channel. The first channel and the second channel are positioned in the third channel, and a complex heat medium flows in the third channel.
In this embodiment, the principle of the lng cold energy power generation apparatus is as follows:
the high pressure LNG enters the first heat exchanger 12 to transfer cold energy to the working medium in a gas phase state, so that the working medium is cooled to a working medium in a low temperature liquid phase state. The working medium in the low-temperature liquid phase state enters a working medium booster pump 13 to be boosted, and the working medium in the low-temperature liquid phase state after being boosted enters a second heat exchanger 14. In the reheating unit 3, the second heat exchanger 14 exchanges heat, and the working medium in the high-pressure low-temperature liquid phase state is gasified and heated to the overheated high-pressure gas phase state, and then enters the expansion generator set 11. The volume of the working medium expands, in the expansion process, the expander drives the generator to do work outwards, so that the LNG cold energy is converted into electric energy, the expanded working medium in a gas phase state enters the first heat exchanger 12 again, and a cycle is completed.
The LNG exchanges heat in the first heat exchanger 12, then enters the third heat exchanger 51, and enters the gas supply pipe network after being reheated to the temperature required by the external pipeline network.
The heat required when the working medium in the high-pressure low-temperature liquid phase state is gasified to the overheat state and the heat for low-temperature natural gas rewarming are provided by the rewarming medium in the rewarming unit 3.
The winter reheating is provided by high-temperature flue gas generated by combustion of combustion gas and air in a combustor.
When power generation is not required, the rankine cycle power generation unit 1 may be closed, the bypass valve 54 may be opened, and only the air supply operation may be performed.
The large LNG receiving station is high-pressure LNG with the pressure of 9.5MPa and the temperature of-145 ℃, the temperature of seawater in winter is 5 ℃, and the circulating working medium is propane. Under the working condition, the power generation amount of each ton of LNG is about 19 KW, the natural gas can be reheated to the normal temperature, and meanwhile, if the power is not generated, the embodiment can be switched to a pure gasification mode. By adopting the device, the LNG cold energy can be efficiently utilized, and the stable power generation state throughout the year can be maintained.
Claims (8)
1. The utility model provides a liquefied natural gas cold energy power generation facility which characterized in that: comprises that
The Rankine cycle power generation unit is loaded with working media; the working medium in the liquid phase state is pressurized and then changed into a high-pressure liquid phase, and after the high-pressure liquid phase is reheated to be in a gas phase state, the volume expansion externally applies work and generates electricity;
the LNG liquid phase pipe is used for introducing LNG in a liquid phase state to the Rankine cycle power generation unit and exchanging heat with working media in a low-pressure gas phase state in the Rankine cycle power generation unit;
the reheating unit is loaded with reheating media and is used for reheating the working medium in a low-temperature liquid phase state to the working medium in an overheated high-temperature gas phase state; and
and the auxiliary heating unit gradually extends from the outside of the reheating unit to the position near the bottom in the reheating unit to heat the reheating medium.
2. The lng cold energy power plant of claim 1, wherein: the Rankine cycle power generation unit includes
An expansion generator set;
the first heat exchanger is provided with a first heat exchange channel and a second heat exchange channel which are independent;
a working medium booster pump;
the second heat exchanger is immersed in the reheating medium of the reheating unit;
the two ends of the first pipeline are respectively connected with the outlet end of the expansion generator set and the inlet end of the second heat exchange channel of the first heat exchanger;
two ends of the second pipeline are respectively connected with the outlet end of the second heat exchange channel of the first heat exchanger and the inlet end of the working medium booster pump;
two ends of the third pipeline are respectively connected with the outlet end of the working medium booster pump and the inlet end of the second heat exchanger; and the number of the first and second groups,
two ends of the fourth pipeline are respectively connected with the outlet end of the second heat exchanger and the inlet end of the expansion generator set;
wherein the LNG liquid phase pipe is communicated with the first heat exchange channel.
3. The lng cold energy power plant of claim 1, wherein: the reheating unit comprises
The pool is a closed structure and is filled with reheating media;
and the exhaust port is connected with the top of the water pool.
4. The lng cold energy power plant of claim 1, wherein: the auxiliary heating unit comprises
A burner having a combustion chamber; the combustion chamber gradually extends from the outside of the reheating unit to the vicinity of the bottom in the reheating unit;
a fan;
a fuel gas pipe connected with the burner; and
and the two ends of the air pipe are respectively connected with the combustor and the fan.
5. The lng cold energy power plant of claim 2, wherein: the plant also includes an LNG supply unit.
6. The lng cold energy power plant of claim 5, wherein: the LNG supply unit comprises
The third heat exchanger is immersed in the reheating medium of the reheating unit;
the two ends of the fifth pipeline are respectively connected with the outlet end of the first heat exchange channel and the inlet end of the third heat exchanger; and
two ends of the sixth pipeline are respectively connected with the outlet end of the third heat exchanger and the gas supply pipe network;
wherein the LNG liquid phase pipe is connected with the inlet end of the first heat exchange channel.
7. The lng cold energy power plant of claim 6, wherein: the second heat exchanger and the third heat exchanger adopt integrated coupling heat exchangers; the coupling heat exchanger is provided with a first channel, a second channel and a third channel; working media flow in the first channel; natural gas flows in the second channel; the first channel and the second channel are positioned in the third channel, and a complex heat medium flows in the first channel and the second channel.
8. The lng cold energy power plant of claim 6, wherein: the LNG gas supply unit further comprises a bypass valve, and two ends of the bypass valve are respectively connected with the LNG liquid phase and the fifth pipeline.
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| CN114439562A (en) * | 2022-01-19 | 2022-05-06 | 杨兆铭 | LNG cold energy efficient mixed refrigerant power generation method |
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