TWI792015B - Liquefied natural gas vaporizer and cold water supply method - Google Patents

Abstract

The liquefied natural gas vaporizer includes: an intermediate medium evaporator that evaporates at least a part of the liquid intermediate medium by exchanging heat between the liquid intermediate medium and water; The gaseous intermediate medium produced by evaporation exchanges heat with the liquefied natural gas to vaporize at least a part of the liquefied natural gas; In the water cooling part for further cooling, the aforementioned natural gas is produced by the gasification of the aforementioned liquefied natural gas in the aforementioned liquefied natural gas vaporization part, and the aforementioned water is cooled by heat exchange with the liquid intermediate medium in the aforementioned intermediate medium evaporation part water.

Description

Liquefied natural gas vaporizer and cold water supply method

The invention relates to a liquefied natural gas vaporizer and a cold water supply method.

Conventionally, as described in Patent Document 1, an intermediate fluid type vaporizer (IFV; Intermediate Fluid type Vaporizer) has been known as a vaporizer for vaporizing liquefied natural gas (LNG). The intermediate medium gasifier, which vaporizes LNG with a heat source such as seawater through an intermediate medium such as propane, can suppress the freezing problem compared with a gasifier that directly exchanges heat between the heat source and LNG.

The intermediate medium type vaporizer described in Patent Document 1 has: an intermediate medium evaporator that evaporates the intermediate medium by exchanging heat between the liquid phase intermediate medium and water; The liquefied natural gas vaporization unit performs heat exchange with the medium to vaporize the liquefied natural gas. In addition, the water cooled by the liquid-phase intermediate medium in the intermediate medium evaporator is introduced into the gas turbine for the gas turbine combined power generation device (GTCC; Gas Turbine Combined Cycle) after flowing out of the intermediate medium evaporator. Air-cooled cooler for driving.

Here, in order to improve the power generation efficiency of GTCC, it may be required to supply cold water at a lower temperature to the air cooler. However, in the intermediate medium type vaporizer described in Patent Document 1, if the temperature of the cold water flowing out from the intermediate medium evaporator is too low (for example, lowered to a lower temperature than 4~5°C), heat transfer may occur. The inner surface of the tube becomes prone to icing problems. Therefore, conventionally, it has been difficult to reduce the temperature of the cold water flowing out from the evaporator while suppressing icing. [Prior Art Literature] [Patent Document]

[Patent Document 1] Japanese Patent Laid-Open No. 2018-119511

SUMMARY OF THE INVENTION The object of the present invention is to provide a liquefied natural gas vaporizer capable of suppressing freezing and lowering the temperature of cold water flowing out of the vaporizer, and a cold water supply method using the same.

A liquefied natural gas vaporizer according to an aspect of the present invention is provided with: an intermediate medium evaporator that evaporates at least a part of the liquid intermediate medium by exchanging heat between the liquid intermediate medium and water; The intermediate medium evaporating section is a liquefied natural gas vaporization section for vaporizing at least a part of the aforementioned liquefied natural gas by exchanging heat between the gaseous intermediate medium produced by evaporating the liquid intermediate medium and the liquefied natural gas; The heat transfer unit heats the natural gas produced by the gasification of the liquefied natural gas in the liquefied natural gas vaporization unit and the water cooled by the heat exchange with the liquid intermediate medium in the intermediate medium evaporation unit. Exchange, the aforementioned water is further cooled.

A cold water supply method according to another aspect of the present invention is a method of supplying the water flowing out of the water cooling unit of the liquefied natural gas vaporizer as cooling water for driving air of a gas turbine combined power generation device.

According to the present invention, it is possible to provide a liquefied natural gas vaporizer capable of suppressing freezing and lowering the temperature of cold water flowing out of the vaporizer, and a cold water supply method using the same.

Hereinafter, a liquefied natural gas vaporizer and a cold water supply method according to an embodiment of the present invention will be described in detail with reference to the drawings.

(Embodiment 1) ＜LNG Vaporizer＞ First, the structure of a liquefied natural gas vaporizer 1 according to Embodiment 1 of the present invention will be described with reference to FIG. 1 . The liquefied natural gas vaporizer 1 of this embodiment is an intermediate medium type vaporizer that vaporizes liquefied natural gas (LNG) with water W1 (such as industrial water) through an intermediate medium, and is installed and used in an LNG base area. As shown in FIG. 1 , the liquefied natural gas vaporizer 1 mainly includes: an intermediate medium evaporation part E1 , a liquefied natural gas vaporization part E2 , a natural gas heating part E3 , and a water cooling part E4 .

The intermediate medium evaporation part E1 evaporates at least a part of the liquid intermediate medium M1 by exchanging heat between the liquid intermediate medium M1 and the water W1. The intermediate medium M1 is a heat medium having a boiling point and a freezing point between the temperature of the water W1 and the temperature of the LNG, such as propane. The intermediate medium evaporator E1 of this embodiment is constituted by a shell-and-tube heat exchanger.

Specifically, as shown in FIG. 1 , the intermediate medium evaporator E1 includes: a housing 10 having a shape long in the horizontal direction and filled with a liquid intermediate medium M1; A plurality of heat transfer tubes 11 in the lower part of the casing 10 . A water inlet chamber 12 is provided on one side of the housing 10 , and a water outlet chamber 13 is provided on the other side of the housing 10 . The plurality of heat transfer tubes 11 communicate with the water inlet chamber 12 and the water outlet chamber 13 respectively, and are arranged in a horizontal posture extending from the water inlet chamber 12 to the water outlet chamber 13 .

In the intermediate medium evaporation part E1, the water W1 flowing into the heat transfer tube 11 from the water inlet chamber 12 is in the process of flowing in the heat transfer tube 11 toward the water outlet chamber 13, and exchanges heat with the liquid intermediate medium M1 ( heat dissipation from the water W1 to the liquid intermediate medium M1 takes place). Thereby, the liquid intermediate medium M1 heat-recovered from the water W1 evaporates to generate the gaseous intermediate medium M2, while the water W1 is cooled by recovering cold heat from the liquid intermediate medium M1. The temperature of the liquid intermediate medium M1 is, for example, about -10 to -5°C, and the temperature of the cooled water W1 is, for example, about 4 to 5°C.

The liquefied natural gas vaporization unit E2 vaporizes at least part of the LNG by exchanging heat between the gaseous intermediate medium M2 produced by evaporating the liquid intermediate medium M1 in the intermediate medium evaporator E1 and the LNG. The liquefied natural gas vaporization unit E2 of this embodiment is constituted by a shell-and-tube heat exchanger similarly to the intermediate medium evaporation unit E1.

As shown in FIG. 1 , the liquefied natural gas vaporization part E2 has: an outer shell 10; On the side of the casing 10 (the upper side of the water outlet chamber 13 ), an LNG inlet chamber 22 and an NG outlet chamber 23 are respectively provided, and the two chambers are separated from each other by a partition plate 24 . The heat transfer pipe 21 has a pipe inlet 21A connected to the LNG inlet chamber 22, and a pipe outlet 21B connected to the NG outlet chamber 23, and has a pipe inlet 21A extending from the pipe inlet 21A to one side in the horizontal direction, then bent, and then from the bent part toward the horizontal direction. The pipe outlet 21B is a shape extending to the other side in the horizontal direction.

In the liquefied natural gas vaporization part E2, LNG flows from the LNG inlet chamber 22 into the heat transfer tube 21, and the gaseous intermediate medium M2 generated in the intermediate medium evaporation part E1 rises to a position near the heat transfer tube 21. In addition, LNG evaporates by recovering heat from the gaseous intermediate medium M2 to generate natural gas (NG; Natural Gas), and the gaseous intermediate medium M2 cooled by the LNG condenses and accumulates on the bottom side of the casing 10 . NG flows into the NG outlet chamber 23 from the tube outlet 21B of the heat transfer tube 21 .

The water cooling part E4 uses the NG produced by the gasification of LNG in the liquefied natural gas vaporization part E2 and the water W1 cooled by the heat exchange between the intermediate medium evaporation part E1 and the liquid intermediate medium M1 through the heat transfer part Heat exchange is performed to further cool the water W1. The water cooling unit E4 of this embodiment is constituted by a shell-and-tube heat exchanger similarly to the intermediate medium evaporation unit E1 and the liquefied natural gas vaporization unit E2. As shown in FIG. 1 , the water cooling unit E4 is connected to the liquefied natural gas vaporization unit E2 through the first connecting pipe 51 , and is connected to the intermediate medium evaporation unit E1 through the second connecting pipe 52 . In addition, the water cooling unit E4 is located on the NG flow path, and is arranged on the downstream side of the liquefied natural gas vaporization unit E2 and on the upstream side of the natural gas heating unit E3 (the liquefied natural gas vaporization unit E2 and the natural gas heating unit E3 between).

More specifically, the water cooling unit E4 has: a casing 41 elongated in the horizontal direction; a U-shaped heat transfer tube 42 arranged in the casing 41; and an NG inlet chamber connected to the tube inlet 42A of the heat transfer tube 42 43 ; and the NG outlet chamber 44 that communicates with the pipe outlet 42B of the heat transfer pipe 42 and partitions the NG inlet chamber 43 by the partition plate 45 .

As shown in FIG. 1 , the upstream end of the first connection pipe 51 is connected to the NG outlet chamber 23 of the liquefied natural gas vaporization unit E2 , and the downstream end is connected to the NG inlet chamber 43 of the water cooling unit E4 . Moreover, the upstream end of the second connection pipe 52 is connected to the water outlet chamber 13 of the intermediate medium evaporator E1, and the downstream end is connected to the water inlet 41A provided on the upper part of the casing 41 of the water cooling unit E4.

The heat transfer tube 42 is used for the flow of NG flowing out from the liquefied natural gas vaporization part E2, and has a shape extending from the tube inlet 42A to one side in the horizontal direction, then bent, and extending from the bent part to the tube outlet 42B to the other side in the horizontal direction. . In the space inside the housing 41, the cooled water W1 flowing out from the intermediate medium evaporator E1 flows in through the second connection pipe 52, and the water W1 flows out of the housing 41 from the water outlet 41B provided at the lower part of the housing 41.

With the aforementioned structure, NG flowing out from the LNG vaporization part E2 (NG outlet chamber 23 ) flows into the NG inlet chamber 43 through the first connecting pipe 51 , and then flows into the heat transfer pipe 42 from the pipe inlet 42A. Then, NG flows from the tube inlet 42A to the tube outlet 42B in the heat transfer tube 42 , and then flows out into the NG outlet chamber 44 .

In addition, the water W1 flowing out from the intermediate medium evaporator E1 (water outlet chamber 13 ) passes through the second connection pipe 52 and flows into the casing 41 from the water inlet 41A. Then, the water W1 exchanges heat with the NG flowing in the heat transfer tube 42 through the tube wall (heat transfer part) of the heat transfer tube 42, recovers cold and heat from the NG, and thereby is cooled to a temperature lower than 4~5°C. Afterwards, it flows out from the water outlet 41B toward the outside of the housing 41. In addition, NG flows out from the tube outlet 42B of the heat transfer tube 42 toward the NG outlet chamber 44 after being heated by recovering heat from the water W1 .

The natural gas heating unit E3 heats the NG by exchanging heat between the NG that has exchanged heat with the water W1 in the water cooling unit E4 and the water W1 before flowing into the intermediate medium evaporation unit E1. The natural gas heating part E3 of this embodiment is the same as the intermediate medium evaporating part E1, the liquefied natural gas vaporizing part E2 and the water cooling part E4. It is composed of a shell-and-tube heat exchanger and is connected to the Water cooling unit E4.

As shown in FIG. 1 , the natural gas heating unit E3 has: a horizontally elongated housing 31 ; a U-shaped heat transfer tube 32 arranged in the housing 31 ; and a NG connected to the pipe inlet 32A of the heat transfer tube 32 . the inlet chamber 33 ; and the NG outlet chamber 34 which communicates with the pipe outlet 32B of the heat transfer pipe 32 and partitions the NG inlet chamber 33 by the partition plate 35 . The upstream end of the third connecting pipe 53 is connected to the NG outlet chamber 44 of the water cooling unit E4, and the downstream end is connected to the NG inlet chamber 33 of the natural gas heating unit E3.

The heat transfer tube 32 is for the flow of NG flowing out of the water cooling part E4, and has a shape extending from the tube inlet 32A to one side in the horizontal direction, then bent, and extending from the bent part to the tube outlet 32B to the other side in the horizontal direction. Cooled water W1 flowing from the intermediate medium evaporator E1 flows into the space inside the housing 31 , and the water W1 flows out of the housing 31 from the water outlet 31B provided at the lower portion of the housing 31 .

In the natural gas heating part E3 , NG flowing out of the water cooling part E4 (NG outlet chamber 44 ) flows into the NG inlet chamber 33 through the third connecting pipe 53 , and then flows into the heat transfer pipe 32 from the pipe inlet 32A. Then, NG flows from the tube inlet 32A to the tube outlet 32B in the heat transfer tube 32 , is warmed by recovering heat from the water W1 flowing into the casing 31 , and then flows out into the NG outlet chamber 34 .

＜Gas Turbine Combined Power Plant＞ Next, the structure of a gas turbine combined power generation device 2 that uses NG generated in the liquefied natural gas vaporizer 1 (NG that flows out of the NG outlet chamber 34 of the natural gas heating unit E3) as fuel to generate electricity will be described mainly with reference to FIG. 2 . . As shown in FIG. 2 , the gas turbine combined power generation device 2 mainly includes: a cooler 81 , an air compressor 82 , a gas turbine 83 , an exhaust heat recovery boiler 84 , a steam turbine 86 , and a gas turbine generator 85 .

The air compressor 82 is used to compress the air cooled by the cooler 81 . The gas turbine 83 combusts NG with the compressed air discharged from the air compressor 82, and is rotationally driven by combustion gas generated by the combustion.

The exhaust heat recovery boiler 84 has a first flow path 84A through which combustion gas flowing out of the gas turbine 83 flows and a second flow path 84B through which water flows, and evaporates water by exchanging heat between the combustion gas and water. The steam turbine 86 is rotationally driven by the steam generated in the exhaust heat recovery boiler 84 . The gas turbine generator 85 is connected to the gas turbine 83 and the steam turbine 86, and converts the rotational energy of the gas turbine 83 and the steam turbine 86 into electric energy.

＜Water cycle mechanism＞ Next, the structure of the water circulation mechanism 3 for circulating the water W1 between the liquefied natural gas vaporizer 1 and the gas turbine combined power generation unit 2 will be described with reference to FIGS. 1 and 2 . As shown in FIG. 1 , the water circulation mechanism 3 has: a cold water supply flow path 62 for supplying water W1 (cold water) from the LNG vaporizer 1 to the cooler 81; and water W1 supplied from the cooler 81 to the LNG vaporizer 1 (Warm water) The warm water supply circulation path 63.

The cold water supply flow path 62 is composed of pipes, the upstream end is connected to the water outlet 41B of the casing 41 of the water cooling unit E4 , and the downstream end is connected to the inlet of the first flow path 81A of the cooler 81 . As shown in FIG. 1, in the cold water supply circulation path 62, from the upstream side of the flow direction of the water W1 toward the downstream side, there are sequentially arranged: a cold water tank 70 storing the water W1 (cold water) from the water cooling unit E4; The water W1 flowing out of the water cooling unit E4 is sent to the cooler 81 by the cold water circulation pump 71 . Furthermore, the cold water tank 70 can also be omitted.

The warm water supply flow path 63 is composed of pipes, the upstream end is connected to the outlet of the first flow path 81A of the cooler 81, and the downstream end is connected to the water inlet chamber 12 of the intermediate medium evaporator E1. In the warm water supply circulation path 63, the water W1 (warm water) flowing out of the cooler 81 is further heated by a heat source such as seawater and then warmed up in order from the upstream side to the downstream side of the flow direction of the water W1. Warm water tank 73 for storing the water W1 flowing out from the cooler 81 ; Furthermore, the backup warmer 72 and the warm water tank 73 can also be omitted respectively.

The water circulation mechanism 3 also has a warm water side branch flow path 63A. As shown in FIG. 1 , the warm water side branch flow path 63A has a function of connecting a portion P1 on the downstream side of the warm water circulation pump 74 in the warm water supply flow path 63 to the water inlet 31A of the casing 31 of the natural gas heating unit E3. the first flow path portion 63AA; and the second flow path portion 63AB connecting the water outlet 31B of the housing 31 to a portion P2 of the warm water supply flow path 63 downstream of the point P1. With this structure, part of the water W1 (warm water) flowing through the warm water supply flow path 63 can be diverted from the point P1, and after passing through the space in the casing 31 of the natural gas heating part E3, at the point P2, it can be connected with The water W1 flowing through the hot water supply flow path 63 is collected.

With the aforementioned configuration, the water W1 can be circulated between the LNG vaporizer 1 and the cooler 81 through the cold water supply flow path 62 and the warm water supply flow path 63 . In this circulation path, the water cooling unit E4 is arranged in series with the intermediate medium evaporator E1 on the downstream side of the intermediate medium evaporator E1 .

＜Cold water supply method＞ Next, the cold water supply method according to Embodiment 1 of the present invention will be described. The cold water supply method of this embodiment is to use the water W1 (cold water) flowing out from the water cooling part E4 (housing 41) of the aforementioned liquefied natural gas vaporizer 1 as cooling air for driving the gas turbine of the gas turbine combined power generation device 2. The method of water supply.

First, by operating the warm water circulation pump 74, the water W1 (warm water) flows through the warm water supply flow path 63 into the water inlet chamber 12 of the intermediate medium evaporator E1. At this time, part of the water W1 is diverted from the point P1 to the warm water side branch flow path 63A (the first flow path portion 63AA), and after passing through the casing 31 of the natural gas heating part E3, it is on the upstream side of the water inlet chamber 12. (Position P2 ) Converge in the hot water supply flow path 63 .

Next, the water W1 flows into the heat transfer tube 11 from the water inlet chamber 12 , and flows through the heat transfer tube 11 from the water inlet chamber 12 toward the water outlet chamber 13 . At this time, heat exchange occurs between the water W1 and the liquid medium M1 through the tube wall of the heat transfer tube 11, and the water W1 recovers cold and heat from the liquid medium M1, thereby cooling down to, for example, 4-5°C. Further, the cooled water W1 (cold water) flows out from the heat transfer tube 11 toward the water outlet chamber 13 .

Next, the water W1 flowing out from the water outlet chamber 13 passes through the second connecting pipe 52 and flows into the casing 41 of the water cooling unit E4. At this time, heat exchange occurs between the water W1 and NG through the tube wall of the heat transfer tube 42, and the water W1 recovers cold and heat from the NG, thereby further cooling down to a lower temperature than 4-5°C. Then, the cooled water W1 flows out from the water outlet 41B of the housing 41 into the cold water supply flow path 62 .

Next, by activating the cold water circulation pump 71, the cooled water W1 cooled by NG in the water cooling unit E4 to a temperature lower than 4 to 5° C. is supplied to the cooler 81 through the cold water supply flow path 62 (the first flow path). path 81A). Thereby, the air sucked into the second flow path 81B of the cooler 81 is cooled by the water W1 (cold water) flowing through the first flow path 81A.

As mentioned above, the liquefied natural gas vaporizer 1 of this embodiment is equipped with the water cooling part E4 which cools the water W1 using the cold heat of NG generated in the liquefied natural gas vaporization part E2. Thereby, as described below, it is possible to suppress the freezing in the re-liquefied natural gas vaporizer 1 and to lower the temperature of the water W1 (cold water) flowing out of the LNG vaporizer 1 to 4-5° C. lower temperature.

That is, as described above, in the liquefied natural gas vaporizer 1 , the liquid intermediate M1 is heated by the water W1 to evaporate, and the LNG is heated by the gaseous intermediate M2 to generate NG. Here, in the intermediate medium evaporator E1, the intermediate medium for heat recovery from the water W1 is changed from a liquid state to a gas. That is, since the liquid intermediate medium M1 recovers heat from the water W1 as latent heat, the critical heat transfer coefficient on the outside of the heat transfer tube 11 (the liquid intermediate medium M1 side) becomes large. Therefore, in the intermediate medium evaporation part E1, the tube wall temperature of the heat transfer tube 11 is affected by the liquid intermediate medium M1 and becomes easy to drop. If the water W1 is lowered to a lower temperature than 4~5°C, the heat transfer tube The concern of icing on the inner surface of the pipe wall of 11 becomes greater.

On the other hand, in the water cooling unit E4, NG is recovered as sensible heat from the water W1. That is, in the water cooling unit E4 , unlike the intermediate medium evaporation unit E1 , there is no change in the state of the medium (NG) on the side that exchanges heat with the water W1 . Therefore, the critical heat transfer coefficient of the inner side (NG side) of the heat transfer tube 42 becomes small, so that the tube wall temperature of the heat transfer tube 42 can be suppressed from decreasing excessively. Therefore, according to the liquefied natural gas vaporizer 1 of this embodiment, if there is a requirement to lower the water W1 to a lower temperature than 4~5°C by the water cooling unit E4, even if the circulation amount of the water W1 is increased, or Freezing of the outer wall surface of the heat transfer tube 42 can also be suppressed without using salt water as the water W1. Moreover, by providing the water cooling unit E4 as a new heat exchange unit, the heat load of other heat exchange units (intermediate medium evaporation unit E1, liquefied natural gas vaporization unit E2, and natural gas heating unit E3) can also be reduced.

(Embodiment 2) Next, the structure of a liquefied natural gas vaporizer 1A according to Embodiment 2 of the present invention will be described with reference to FIG. 3 . The liquefied natural gas vaporizer 1A of the second embodiment basically has the same structure as the liquefied natural gas vaporizer 1 of the aforementioned embodiment 1 and can achieve the same effect, but the structure of the natural gas heating part E3 is omitted. It is different from the first embodiment described above.

As shown in FIG. 3 , the LNG vaporizer 1A of Embodiment 2 is constituted by three heat exchange parts of an intermediate medium evaporation part E1 , a LNG vaporization part E2 and a water cooling part E4 . Such a liquefied natural gas vaporizer 1A can be used in applications where the supply of NG at a low temperature near 0° C. is required instead of the supply of normal-temperature NG.

As described above, the embodiments disclosed so far are merely examples, and are not intended to limit the embodiments of the present invention. The scope of the present invention is not limited to the foregoing description, and various changes can be made within the meaning and range equivalent to the claims, and such changes are also included in the present invention. Therefore, the scope of the present invention also includes the following embodiments.

In the above-mentioned Embodiment 1, the case where the water cooling part E4 is comprised by the fin-tube heat exchanger was demonstrated, but it is not limited to this. The water cooling unit E4 may also be constituted by, for example, a plate heat exchanger, a fixed tube plate heat exchanger, or the like. In addition, the natural gas heating unit E3 may be constituted by, for example, a plate heat exchanger, a fixed tube plate heat exchanger, or the like.

Also, in FIG. 1 , the water W1 flows from the upper side to the lower side in the housings 31 and 41 of the natural gas heating part E3 and the water cooling part E4, but in the housings 31 and 41, the water W1 It can also flow from the lower side to the upper side. That is, the water inlets may be formed in the lower parts of the casings 31 and 41 respectively, and the water outlets may be formed in the upper parts of the casings 31 and 41 respectively.

Also, in FIG. 1 , it is shown that in the natural gas heating part E3 and the water cooling part E4, NG flows inside the heat transfer tubes 32, 42, and water W1 flows outside the heat transfer tubes 32, 42, but not limited to this. That is, a structure may be adopted in which water W1 flows inside the heat transfer tubes 32 and 42 and NG flows outside the heat transfer tubes 32 and 42 (spaces in the housings 31 and 41 ).

In Embodiment 1, the structure in which part of the water W1 (warm water) is divided into the natural gas heating part E3 has been described, but the entire amount of the water W1 (warm water) may be evaporated to the natural gas heating part E3 and the intermediate medium. Part E1 circulates continuously.

In the first embodiment, the cooling of the air for driving the gas turbine of the gas turbine combined power generation unit 2 was described as the use of the water W1 (cold water) flowing out from the water cooling unit E4, but the present invention is not limited thereto. For example, the cooled water W1 can also be used for other uses such as heat exchangers for cooling air used in various facilities, cooling of cables for power generation, and the like.

In addition, the foregoing embodiment will be briefly described as follows.

The liquefied natural gas vaporizer of the aforementioned embodiment includes: an intermediate medium evaporating unit that evaporates at least a part of the liquid intermediate medium by exchanging heat between the liquid intermediate medium and water; An evaporating section is an liquefied natural gas vaporization section that vaporizes at least a part of the liquefied natural gas by exchanging heat between the gaseous intermediate medium produced by evaporating the liquid intermediate medium and the liquefied natural gas; and by passing natural gas and water through the heat transfer section A water cooling unit for further cooling the aforementioned water through heat exchange. The aforementioned natural gas is produced by vaporizing the aforementioned liquefied natural gas in the aforementioned liquefied natural gas vaporization unit. The heat exchange medium is cooled water.

The inventors of the present invention carefully examined a liquefied natural gas vaporizer regarding a proposal for suppressing freezing and lowering the temperature of cold water flowing out of the vaporizer, and came up with the present invention based on the following knowledge.

Generally, in an intermediate medium type LNG vaporizer, the liquid intermediate medium is heated by water to evaporate, and the liquefied natural gas is heated by the gaseous intermediate medium to produce natural gas. Here, in the intermediate medium evaporator where heat is exchanged between water and the intermediate medium, since the intermediate medium recovered from water heat changes from a liquid phase to a gas phase, the critical heat transfer coefficient on the intermediate medium side becomes large. Therefore, in the intermediate medium evaporation part, the temperature of the heat transfer tube wall tends to drop closer to the temperature of the intermediate medium than the temperature of the water. From the above reasons, it can be seen that in the conventional LNG vaporizer, it is extremely difficult to further reduce the temperature of the cold water flowing out of the vaporizer while suppressing freezing.

Therefore, the inventors of this application conceived, as a solution to the above-mentioned problems, to provide a water cooling unit that utilizes the cold and heat of natural gas generated in the liquefied natural gas vaporization unit to further cool the water cooled by the liquid intermediate medium in the intermediate medium evaporation unit. cool down. In this water cooling section, since there is no state change when natural gas is recovered from water heat, the critical heat transfer coefficient on the natural gas side becomes smaller than that on the intermediate medium side of the intermediate medium evaporation section. Therefore, in the water cooling section, the temperature of the heat transfer tube wall becomes less likely to drop than in the intermediate medium evaporating section. Therefore, according to the liquefied natural gas vaporizer of the aforementioned embodiment, even when the temperature of the cold water flowing out of the vaporizer is lowered to a lower temperature than, for example, 4 to 5° C., freezing in the vaporizer can be suppressed.

The liquefied natural gas vaporizer may further include a natural gas heating unit that heats the natural gas that has been heat-exchanged with the water in the water cooling unit and the water before flowing into the intermediate medium evaporator, thereby converting the Natural gas heating.

According to this structure, the temperature of the natural gas can be easily raised to the required temperature.

The cold water supply method of the aforementioned embodiment is a method of supplying the water flowing out from the water cooling unit of the liquefied natural gas vaporizer as cooling water for driving air of a gas turbine combined power generation device.

According to this method, the air for driving the gas turbine can be cooled by the cold water cooled to a sufficiently low temperature in the water cooling section. Thereby, since the water content of the air is reduced, the combustion efficiency is improved, and as a result, the power generation efficiency of the gas turbine combined power generation device can be improved.

1: Liquefied natural gas vaporizer 2: Gas turbine combined power generation device 3: Water cycle mechanism 10: Shell 11: Heat transfer tube 12: Water entrance chamber 13: Water outlet chamber 21: heat transfer tube 21A: Tube inlet 21B: Pipe outlet 22:LNG entrance chamber 23:NG export room 24: Partition board 31: shell 31A: Water inlet 31B: Water outlet 32: heat transfer tube 32A: Tube inlet 32B: Pipe outlet 33:NG entrance room 34:NG export room 41: Shell 42: heat transfer tube 42A: Tube inlet 42B: Pipe outlet 43:NG entrance room 44:NG export room 45: Partition board 51: The first connecting pipe 52: The second connecting pipe 53: The third connecting pipe 62: Cold water supply circulation path 63: Warm water supply circulation path 63A: Warm water side branch flow path 63AA: 1st circulation route part 63AB: 2nd circulation path part 70: cold sink 71: Cold water circulation pump 72: rear spare heater 73: warm water tank 74: Warm water circulation pump 81: Cooler 81A: 1st distribution path 81B: Second circulation path 82:Air compressor 83: gas turbine 83A: 1st circulation path 83B: Second distribution path 84: Exhaust heat recovery boiler 85: gas turbine generator 86: steam turbine E1: intermediate medium evaporation department E2: Liquefied Natural Gas Gasification Department E3: Natural gas heating department E4: water cooling department LNG: liquefied natural gas M1: intermediate medium NG: natural gas W1: water

[ Fig. 1 ] is a diagram schematically showing the structure of a liquefied natural gas vaporizer according to Embodiment 1 of the present invention. [ Fig. 2 ] is a diagram schematically showing the structure of a gas turbine combined power generation device. [ Fig. 3 ] is a diagram schematically showing the structure of a liquefied natural gas vaporizer according to Embodiment 2 of the present invention.

1: Liquefied natural gas vaporizer

3: Water cycle mechanism

10: Shell

11: Heat transfer tube

12: Water entrance chamber

13: Water outlet chamber

21: heat transfer tube

21A: Tube inlet

21B: Pipe outlet

22:LNG entrance chamber

23:NG export room

24: Partition board

31: shell

31A: Water inlet

31B: Water outlet

32: heat transfer tube

32A: Tube inlet

32B: Pipe outlet

33:NG entrance room

34:NG export room

35: Partition board

41: Shell

41A: Water inlet

41B: Water outlet

42: heat transfer tube

42A: Tube inlet

42B: Pipe outlet

43:NG entrance room

44:NG export room

45: Partition board

51: The first connecting pipe

52: The second connecting pipe

53: The third connecting pipe

62: Cold water supply circulation path

63: Warm water supply circulation path

63A: Warm water side branch flow path

63AA: 1st circulation route part

63AB: Part 2 of the circulation path

70: cold sink

71: Cold water circulation pump

72: rear spare heater

73: warm water tank

74: Warm water circulation pump

81: Cooler

81A: 1st distribution path

81B: Second circulation path

E1: intermediate medium evaporation department

E2: Liquefied Natural Gas Gasification Department

E3: Natural gas heating department

E4: water cooling department

LNG: liquefied natural gas

M1, M2: intermediate medium

NG: natural gas

P1, P2: parts

W1: water

Claims (2)

A liquefied natural gas vaporizer, comprising: an intermediate medium evaporator, which evaporates at least a part of the liquid intermediate medium by exchanging heat between the liquid intermediate medium and water; At least a part of the liquefied natural gas is vaporized by exchanging heat between the gaseous intermediate medium produced by evaporating the liquid intermediate medium in the intermediate medium evaporating section and the liquefied natural gas; The heat transfer unit heats the natural gas produced by the gasification of the liquefied natural gas in the liquefied natural gas vaporization unit and the water cooled by the heat exchange with the liquid intermediate medium in the intermediate medium evaporation unit. In exchange, the aforementioned water is further cooled and supplied as cooling water for the driving air of the gas turbine combined power generation device. The liquefied natural gas vaporizer according to claim 1, further comprising a natural gas heating part, which is made by making the natural gas which exchanges heat with the water in the water cooling part and the natural gas before flowing into the intermediate medium evaporating part The water performs heat exchange, warming the aforementioned natural gas.

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