KR102522339B1 - Liquefied natural gas vaporizer and cold water supply method - Google Patents

Abstract

The liquefied natural gas vaporizer includes an intermediate medium evaporation unit for evaporating at least a part of the liquid intermediate medium by heat exchange between the liquid intermediate medium and water, and a gas phase generated by evaporating the liquid intermediate medium in the intermediate medium evaporation unit. A liquefied natural gas vaporizing unit for vaporizing at least a portion of the liquefied natural gas by heat exchange between the intermediate medium and the liquefied natural gas, and natural gas generated by vaporizing the liquefied natural gas in the liquefied natural gas vaporizing unit; A water cooling unit for further cooling the water by exchanging heat through a heat transfer unit with the water cooled by heat exchange with the liquid intermediate medium in the intermediate medium evaporation unit is provided.

Description

Liquefied natural gas vaporizer and cold water supply method

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

Conventionally, as described in Patent Document 1, as a vaporizer for vaporizing liquefied natural gas (LNG), an intermediate fluid type vaporizer (IFV) is known. An intermediate medium type vaporizer vaporizes LNG by a heat source such as seawater through an intermediate medium such as propane, and can suppress icing trouble compared to a vaporizer that directly exchanges heat between the heat source and LNG.

The intermediate medium type vaporizer described in Patent Document 1 includes an intermediate medium evaporation unit that evaporates the intermediate medium by exchanging heat between the liquid intermediate medium and water, and a liquefied natural gas vaporizing the liquefied natural gas by exchanging heat between the liquefied natural gas and the gaseous intermediate medium. It has a gas vaporizer. In addition, after the water cooled by the liquid intermediate medium in the intermediate medium evaporation unit flows out from the intermediate medium evaporation unit, it supplies air for driving a gas turbine in a gas turbine combined power generation device (GTCC; Gas Turbine Combined Cycle). It is introduced into a cooler to cool it.

Here, in order to increase the power generation efficiency in the GTCC, it is sometimes required to supply colder 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 (eg lowered to a temperature lower than 4 to 5° C.), ice icing is likely to occur on the inner surface of the heat transfer tube. has a problem Therefore, conventionally, there is a problem that it is difficult to lower the temperature of cold water flowing out of the vaporizer while suppressing icing.

Japanese Unexamined Patent Publication No. 2018-119511

An object of the present invention is to provide a liquefied natural gas vaporizer capable of lowering the temperature of cold water flowing out of the vaporizer while suppressing icing, and a method for supplying cold water using the liquefied natural gas vaporizer.

The liquefied natural gas vaporizer according to one aspect of the present invention comprises an intermediate medium evaporator for evaporating at least a part of the liquid intermediate medium by heat exchange between the liquid intermediate medium and water, and the intermediate medium evaporator of the liquid phase in the intermediate medium evaporation unit. A liquefied natural gas vaporizing unit for vaporizing at least a part of the liquefied natural gas by heat-exchanging the liquefied natural gas with the gaseous intermediate medium generated by evaporation of the medium, and the liquefied natural gas vaporizing in the liquefied natural gas vaporizing unit A water cooling unit for further cooling the water by exchanging heat with the generated natural gas and the water cooled by heat exchange with the liquid intermediate medium in the intermediate medium evaporation unit through a heat transfer unit is provided.

A cold water supply method according to another aspect of the present invention is a method of supplying the water flowing out from the water cooling part of the liquefied natural gas vaporizer as cooling water for gas turbine drive air in a gas turbine combined power generator. .

ADVANTAGE OF THE INVENTION According to this invention, the liquefied natural gas vaporizer which can lower the temperature of the cold water flowing out from the vaporizer while suppressing icing, and the cold water supply method using this liquefied natural gas vaporizer can be provided.

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

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

(Embodiment 1)

<Liquefied Natural Gas Vaporizer>

First, the configuration 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 according to the present embodiment is an intermediate medium type vaporizer that vaporizes liquefied natural gas (LNG) with water W1 (eg industrial water) through an intermediate medium, installed in an LNG base area, used As shown in Fig. 1, the liquefied natural gas vaporizer 1 mainly includes an intermediate medium evaporation unit E1, a liquefied natural gas evaporation unit E2, a natural gas warming unit E3, and a water cooling unit E4.

The intermediate medium evaporation unit 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. Intermediate medium M1 is a thermal medium having a boiling point and condensation point between the temperature of water W1 and the temperature of LNG, for example propane. The intermediate medium evaporation unit E1 in this embodiment is constituted by a shell-and-tube type heat exchanger.

Specifically, as shown in FIG. 1, the intermediate medium evaporation unit E1 has a horizontally long shape and is immersed in the shell 10 filled with the liquid intermediate medium M1 and the liquid intermediate medium M1. It has a plurality of heat transfer tubes (11) disposed in the lower portion of the shell (10). A water inlet chamber 12 is provided on one side of the shell 10, and a water outlet chamber 13 is provided on the other side of the shell 10. Each of the plurality of heat transfer pipes 11 communicates with the water inlet chamber 12 and the water outlet chamber 13, and is arranged in a horizontal posture extending from the water inlet chamber 12 to the water outlet chamber 13. .

In the intermediate medium evaporation section E1, the water W1 flowing into the heat transfer tube 11 from the water inlet chamber 12 exchanges heat with the liquid intermediate medium M1 in the process of flowing in the heat transfer tube 11 toward the water outlet chamber 13. (Heat dissipation from water W1 to liquid intermediate medium M1 occurs). As a result, the liquid intermediate M1 recovered from the heat from the water W1 evaporates to produce a gaseous intermediate M2, while the water W1 is cooled by recovering cooling heat from the liquid intermediate M1. The temperature of the liquid intermediate medium M1 is, for example, about -10 to -5°C, and the temperature of the water W1 after cooling is, for example, about 4 to 5°C.

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

As shown in FIG. 1, the liquefied natural gas vaporization unit E2 includes a shell 10 and a U-shaped heat transfer tube 21 disposed on the upper side of the shell 10 (above the liquid level of the intermediate medium M1). has On the side of the shell 10 (above the water outlet chamber 13), an LNG inlet chamber 22 and an NG outlet chamber 23 are provided, respectively, and both chambers are partitioned off from each other by a partition plate 24. The heat transfer pipe 21 has a tube inlet 21A communicating in the LNG inlet chamber 22 and a tube outlet 21B communicating in the NG outlet chamber 23, and extends from the tube inlet 21A to one side in the horizontal direction. After being bent, it has a shape extending from the bent portion toward the other side in the horizontal direction toward the pipe outlet 21B.

In the liquefied natural gas vaporization section E2, while LNG flows into the heat transfer tube 21 from the LNG inlet chamber 22, the gaseous intermediate medium M2 generated in the intermediate medium evaporation section E1 rises to a position near the heat transfer tube 21. . Then, LNG evaporates by recovering heat from the gaseous intermediate medium M2 to generate natural gas (NG), while the gaseous intermediate M2 cooled by the LNG condenses and pools on the bottom side in the shell 10 . NG flows out into the NG outlet chamber 23 from the tube outlet 21B of the heat transfer pipe 21 .

The water cooling unit E4 heats NG generated by vaporizing LNG in the liquefied natural gas vaporizing unit E2 and water W1 cooled by heat exchange with the liquid intermediate M1 in the intermediate medium evaporation unit E1 through the heat transfer unit, Cool the water W1 further. The water cooling part E4 in this embodiment is comprised by the shell-and-tube heat exchanger similarly to the intermediate medium evaporation part E1 and the liquefied natural gas vaporizing part E2. As shown in Fig. 1, the water cooling unit E4 is connected to the liquefied natural gas vaporization unit E2 through the first communication pipe 51 and connected to the intermediate medium evaporation unit E1 through the second communication tube 52. has been In addition, the water cooling unit E4 is on the NG flow path, on the downstream side of the liquefied natural gas vaporizing unit E2 and upstream of the natural gas warming unit E3 (between the liquefied natural gas vaporizing unit E2 and the natural gas warming unit E3) are placed

More specifically, the water cooling unit E4 includes a horizontally elongated shell 41, a U-shaped heat transfer tube 42 disposed in the shell 41, and a tube inlet 42A of the heat transfer tube 42. It has an NG inlet chamber 43 communicating with the NG inlet chamber 43 and an NG outlet chamber 44 communicating with the pipe outlet 42B of the heat transfer pipe 42 and partitioned from the NG inlet chamber 43 by a partition plate 45. there is.

As shown in Fig. 1, the upstream end of the first communication 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 of the water cooling unit E4. It is connected to (43). In addition, while the 2nd communication pipe 52 is connected to the water outlet chamber 13 of the intermediate medium evaporation part E1 at the upstream end, the water inlet provided at the upper part of the shell 41 of the water cooling part E4 at the downstream end ( 41A) is connected.

The heat transfer tube 42 is one through which NG flowed out from the liquefied natural gas vaporization unit E2 is circulated, and is bent after extending from the tube inlet 42A in one side in the horizontal direction, and from the bent portion toward the tube outlet 42B in the horizontal direction on the other side. It has a shape that extends to the side. Into the space within the shell 41, the cooled water W1 flowing out from the intermediate medium evaporation unit E1 flows in through the second communication pipe 52, and the water W1 flows through the water outlet 41B provided at the lower part of the shell 41. out of the shell 41.

With the above configuration, NG flowed out from the liquefied natural gas vaporization unit E2 (NG outlet chamber 23) flows into the NG inlet chamber 43 through the first communication pipe 51, and then enters the pipe inlet 42A. It is introduced into the heat transfer pipe 42 from there. Then, NG flows through the inside of the heat transfer tube 42 from the tube inlet 42A toward the tube outlet 42B, and then flows out into the NG exit chamber 44 .

On the other hand, the water W1 flowed out from the intermediate medium evaporation part E1 (water outlet chamber 13) flows into the shell 41 from the water inlet 41A through the second communication pipe 52. Then, the water W1 is cooled to a lower temperature than 4 to 5° C. by exchanging heat with NG flowing through the heat transfer pipe 42 through the tube wall portion (heat transfer portion) of the heat transfer pipe 42 and recovering cold heat from the NG, Water flows out of the shell 41 from the outlet 41B. On the other hand, NG flows out into the NG exit chamber 44 from the pipe outlet 42B of the heat transfer tube 42 after being heated by recovering heat from the water W1.

The natural gas warming part E3 warms NG by heat-exchanging NG heat-exchanged with the water W1 in the water cooling part E4, and water W1 before flowing into the intermediate medium evaporation part E1. The natural gas warming unit E3 in this embodiment is constituted by a shell-and-tube type heat exchanger, similarly to the intermediate medium evaporation unit E1, the liquefied natural gas vaporization unit E2, and the water cooling unit E4, and the third communication pipe 53 It is connected to the water cooler E4.

As shown in FIG. 1, the natural gas warming unit E3 includes a shell 31 having a horizontally elongated shape, a U-shaped heat transfer tube 32 disposed in the shell 31, and a tube of the heat transfer tube 32 The NG inlet chamber 33 communicating with the inlet 32A and the NG exit chamber communicating with the pipe outlet 32B of the heat transfer pipe 32 and partitioned from the NG inlet chamber 33 by the partition plate 35 ( 34) have. The third communication pipe 53 has an upstream end connected to the NG exit chamber 44 of the water cooling section E4, and a downstream end connected to the NG inlet chamber 33 of the natural gas warming section E3.

The heat transfer tube 32 is one through which NG flowed out from the water cooling unit E4 flows, and is bent after extending from the tube inlet 32A to one side in the horizontal direction, and extends from the bent portion to the other side in the horizontal direction toward the tube outlet 32B has the shape of The water W1 before flowing in from the intermediate medium evaporation section E1 flows into the space within the shell 31, and the water W1 flows out of the shell 31 from the water outlet 31B provided in the lower part of the shell 31. .

In the natural gas warming part E3, NG flowed out from the water cooling part E4 (NG outlet chamber 44) flows into the NG inlet chamber 33 through the third communication pipe 53, and then the pipe inlet 32A It flows into the heat transfer pipe 32 from there. Then, NG is warmed by recovering heat from the water W1 flowing into the shell 31 in the process of flowing through the heat transfer pipe 32 from the pipe inlet 32A toward the pipe outlet 32B, and the NG outlet chamber 34 leaked out to

<Gas turbine combined generator>

Next, the configuration of the gas turbine combined power generation device 2 that generates power from the NG generated in the liquefied natural gas vaporizer 1 (NG discharged from the NG exit chamber 34 of the natural gas warming unit E3) as fuel, Description will be made mainly with reference to FIG. 2 . As shown in FIG. 2 , the gas turbine combined generator 2 includes a cooler 81, an air compressor 82, a gas turbine 83, a waste heat recovery boiler 84, and a steam turbine 86 ) and a gas turbine generator 85.

The air compressor 82 compresses the air cooled by the cooler 81 . The gas turbine 83 is rotationally driven by the combustion gas generated by the combustion of NG by the compressed air discharged from the air compressor 82, and the combustion.

The waste heat recovery boiler 84 has a first flow path 84A through which combustion gas flowed out from the gas turbine 83 flows, and a second flow path 84B through which water flows, and heat exchange between the combustion gas and water. By doing so, water evaporates. The steam turbine 86 is driven to rotate by steam generated in the waste heat recovery boiler 84 . The gas turbine generator 85 is connected to the gas turbine 83 and the steam turbine 86, and converts rotational energy of the gas turbine 83 and the steam turbine 86 into electrical energy.

<Water Circulation Mechanism>

Next, the structure of the water circulation mechanism 3 which circulates the water W1 between the liquefied natural gas vaporizer 1 and the gas turbine combined power generator 2 is demonstrated with reference to FIGS. 1 and 2. FIG. As shown in FIG. 1 , the water circulation mechanism 3 includes a cold water supply passage 62 for supplying water W1 (cold water) from the liquefied natural gas vaporizer 1 to the cooler 81, and from the cooler 81 It has a hot water supply passage 63 for supplying water W1 (hot water) to the liquefied natural gas vaporizer 1.

The cold water supply passage 62 is constituted by piping, and the upstream end is connected to the water outlet 41B of the shell 41 of the water cooling unit E4, and the downstream end is the first of the cooler 81. It is connected to the inlet of the flow path 81A. 1, in the cold water supply passage 62, there is a cold water tank 70 for storing water W1 (cold water) flowing out from the water cooling unit E4, and a cooler ( 81), cold water circulation pumps 71 are disposed sequentially from the upstream side to the downstream side in the flow direction of the water W1. Also, the cold water tank 70 may be omitted.

The hot water supply passage 63 is constituted by piping, and while the upstream end is connected to the outlet of the first flow passage 81A of the cooler 81, the downstream end is the water inlet chamber of the intermediate medium evaporation unit E1. It is connected to (12). In the hot water supply passage 63, a backup warmer 72 for further heating the water W1 (hot water) flowing out from the cooler 81 by a heat source such as seawater, and storing the water W1 flowing out from the cooler 81 and a hot water circulation pump 74 for sending the water W1 flowing out from the cooler 81 toward the liquefied natural gas vaporizer 1, sequentially from the upstream side to the downstream side in the flow direction of the water W1. are placed In addition, the backup warmer 72 and the hot water tank 73 may be respectively omitted.

The water circulation mechanism 3 further has a warm water side branch flow path 63A. As shown in FIG. 1 , the hot water side branch passage 63A is located downstream of the hot water circulation pump 74 in the hot water supply passage 63 at the water inlet of the shell 31 of the natural gas warming unit E3 and the region P1 ( 31A), and a second flow path portion 63AB connecting the water outlet 31B of the shell 31 and the part P2 on the downstream side of the part P1 in the hot water supply passage 63 has With this configuration, part of the water W1 (hot water) flowing through the hot water supply passage 63 is diverted from the part P1, and after passing through the space in the shell 31 of the natural gas warming part E3, the hot water in the part P2 The water W1 flowing through the supply passage 63 can be joined.

With the above configuration, water W1 can be circulated between the liquefied natural gas vaporizer 1 and the cooler 81 through the cold water supply passage 62 and the hot water supply passage 63 . On this circulation passage WHEREIN: On the downstream side of the intermediate medium evaporation part E1, the water cooling part E4 is arrange|positioned in series with the said intermediate medium evaporation part E1.

<How to supply cold water>

Next, the cold water supply method according to Embodiment 1 of the present invention will be described. In the cold water supply method according to the present embodiment, the water W1 (cold water) flowing out from the water cooling part E4 (shell 41) of the liquefied natural gas vaporizer 1 is used in the gas turbine combined power generator 2 This is a method of supplying air as cooling water for driving a gas turbine.

First, by operating the hot water circulation pump 74, water W1 (hot water) is introduced into the water inlet chamber 12 of the intermediate medium evaporation unit E1 through the hot water supply passage 63. At this time, part of the water W1 is diverted from the part P1 to the warm water side branch passage 63A (first passage part 63AA), and after passing through the inside of the shell 31 of the natural gas warming part E3, the water inlet chamber ( It may join the hot water supply passage 63 immediately upstream of 12) (part P2).

Next, while the water W1 flows into the heat transfer tube 11 from the water inlet chamber 12, it is made to flow through the inside of the heat transfer tube 11 from the water inlet chamber 12 toward the water outlet chamber 13. At this time, heat exchange between the water W1 and the liquid intermediate medium M1 occurs through the tube wall portion of the heat transfer tube 11, and the water W1 is cooled to about 4 to 5°C by recovering cold heat from the liquid intermediate medium M1. Then, the cooled water W1 (cold water) flows out from the heat transfer pipe 11 to the water outlet chamber 13 .

Next, the water W1 flowing out from the water outlet chamber 13 is introduced into the shell 41 of the water cooling unit E4 through the second communication pipe 52. At this time, heat exchange between the water W1 and NG occurs through the tube wall portion of the heat transfer tube 42, and the water W1 is further cooled down to a lower temperature than 4 to 5°C by recovering cold heat from the NG. Then, the cooled water W1 flows out into the cold water supply passage 62 from the water outlet 41B of the shell 41 .

Next, by operating the cold water circulation pump 71, the water W1 cooled to a temperature lower than 4 to 5° C. by NG in the water cooling unit E4 is passed through the cold water supply passage 62 to the cooler 81 (first passage ( 81A)). For this reason, 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 described above, the liquefied natural gas vaporizer 1 according to the present embodiment includes the water cooling unit E4 that cools the water W1 using the cooling heat of NG generated in the liquefied natural gas vaporizing unit E2. As a result, the temperature of the water W1 (cold water) flowing out of the liquefied natural gas vaporizer 1 can be lowered to a lower temperature than 4 to 5°C while suppressing icing in the liquefied natural gas vaporizer 1 as follows. there is.

That is, as described above, in the liquefied natural gas vaporizer 1, the liquid intermediate medium M1 is heated by the water W1 and evaporated, and LNG is heated by the gaseous intermediate medium M2 to generate NG. Here, in the intermediate medium evaporation unit E1, the state of the intermediate medium recovered from the water W1 changes from liquid to gas. That is, since the liquid intermediate medium M1 recovers heat from the water W1 as latent heat, the transmembrane heat transfer coefficient on the outside of the heat transfer pipe 11 (liquid intermediate medium M1 side) increases. Therefore, in the intermediate medium evaporation section E1, the temperature of the tube wall of the heat transfer tube 11 is easily lowered by the influence of the liquid intermediate M1, and when the water W1 is lowered to a temperature lower than 4 to 5° C., the inner surface of the tube wall of the heat transfer tube 11 The risk of icing increases.

On the other hand, in the water cooler E4, NG recovers heat from the water W1 as sensible heat. That is, in the water cooling section E4, unlike the intermediate medium evaporation section E1, the state change of the medium NG on the other side that exchanges heat with the water W1 does not occur. For this reason, the transmembrane heat transfer coefficient on the inner side (NG side) of the heat transfer tube 42 is reduced, and accordingly, the tube wall temperature of the heat transfer tube 42 can be suppressed from being excessively lowered. Therefore, according to the liquefied natural gas vaporizer 1 according to the present embodiment, when there is a request to cool the water W1 to a lower temperature than 4 to 5° C. by the water cooling unit E4, the amount of circulation of the water W1 is increased, or Even without using brine water or the like as the water W1, icing on the outer wall surface of the heat transfer pipe 42 can be suppressed. In addition, by providing the water cooling section E4 as a new heat exchange section, it is also possible to reduce the heat load in the other heat exchange sections (intermediate medium evaporation section E1, liquefied natural gas vaporization section E2, and natural gas warming section E3).

(Embodiment 2)

Next, the configuration of the 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 according to Embodiment 2 basically has the same configuration as the liquefied natural gas vaporizer 1 according to Embodiment 1 and exhibits the same operation and effect, but natural gas heating It differs from the first embodiment in that the configuration of section E3 is omitted.

As shown in FIG. 3, the liquefied natural gas vaporizer 1A according to Embodiment 2 is constituted by three heat exchange units: an intermediate medium evaporation unit E1, a liquefied natural gas vaporization unit E2, and a water cooling unit E4. Such a liquefied natural gas vaporizer 1A can be used in applications where supply of NG at normal temperature is not required and supply of NG at a low temperature around 0°C is required.

Embodiment disclosed as mentioned above is an illustration in all points, and it should be interpreted that it is not restrictive. The scope of the present invention is presented by the claims rather than the above description, and it is intended that all changes within the meaning and range equivalent to the claims are included. Therefore, the following embodiments are also included in the scope of the present invention.

In the first embodiment, the case where the water cooling unit E4 is constituted by a fin-and-tube type heat exchanger has been described, but it is not limited thereto. The water cooling unit E4 may be constituted by, for example, a plate type heat exchanger or a fixed tube plate type heat exchanger. Further, the natural gas warming unit E3 may also be constituted by a plate type heat exchanger or a fixed tube plate type heat exchanger.

1 shows a case where water W1 flows from the upper side to the lower side in the shells 31 and 41 of the natural gas warming unit E3 and the water cooling unit E4, but in the shells 31 and 41 Water W1 may flow from the lower side toward the upper side. That is, while the water inlets are respectively formed in the lower portions of the shells 31 and 41, the water outlets may be formed in the upper portions of the shells 31 and 41, respectively.

1, in each of the natural gas warming section E3 and the water cooling section E4, NG flows inside the heat transfer tubes 32, 42 and water W1 flows outside the heat transfer tubes 32, 42. , but is not limited thereto. That is, while the water W1 flows through the inside of the heat transfer tubes 32 and 42, the configuration in which NG flows through the outside of the heat transfer tubes 32 and 42 (the space within the shells 31 and 41) may be used.

In the above Embodiment 1, the configuration in which a part of the water W1 (hot water) is divided into the natural gas warming unit E3 has been described, but the entire amount of the water W1 (hot water) is continuously transferred to the natural gas warming unit E3 and the intermediate medium evaporation unit E1. may be distributed.

In the first embodiment, the cooling of the air for driving the gas turbine in the gas turbine combined power generator 2 has been described as an application in which the water W1 (cold water) flowing out from the water cooling unit E4 is used, but it is limited to this. It doesn't work. For example, it is possible to use the water W1 after cooling for other uses, such as cooling heat exchangers used for cooling various facilities and power generation cables.

In addition, when the said embodiment is explained schematically, it is as follows.

The liquefied natural gas vaporizer according to the above embodiment comprises an intermediate medium evaporation unit for evaporating at least a part of the liquid intermediate medium by heat exchange between the liquid intermediate medium and water, and in the intermediate medium evaporation unit, the liquid intermediate medium A liquefied natural gas vaporizing unit for vaporizing at least a part of the liquefied natural gas by heat-exchanging the liquefied natural gas with the gaseous intermediate medium generated by evaporation; A water cooling unit for further cooling the water by exchanging heat with natural gas and the water cooled by heat exchange with the liquid intermediate medium in the intermediate medium evaporation unit through a heat transfer unit is provided.

The inventors of the present invention intensively studied measures for lowering the temperature of cold water flowing out from the vaporizer while suppressing icing in a liquefied natural gas vaporizer, obtained the following findings, and reached the present invention.

Generally, in an intermediate medium type liquefied natural gas vaporizer, the liquid intermediate medium is heated by water to evaporate, and the liquefied natural gas is heated by the gaseous intermediate medium to generate natural gas. Here, in the intermediate medium evaporation section for heat exchange between water and the intermediate medium, since the state of the intermediate medium recovered from water is changed from a liquid phase to a gas phase, the transmembrane heat transfer coefficient on the intermediate medium side increases. For this reason, in the intermediate medium evaporation section, the temperature of the heat transfer tube wall is closer to the temperature of the intermediate medium than the temperature of water, and tends to be lowered. For this reason, in the conventional liquefied natural gas vaporizer, it is difficult to further lower the temperature of cold water flowing out of the vaporizer while suppressing icing.

Therefore, the inventors of the present invention, as a measure to solve the above problem, water cooling in which the water cooled by the liquid intermediate medium in the intermediate medium evaporation unit is further cooled by using the cooling heat of natural gas generated in the liquefied natural gas vaporization unit. It was conceived to create wealth. In this water cooling section, since no state change occurs when natural gas recovers heat from water, the transmembrane heat transfer coefficient on the natural gas side is smaller than the transmembrane heat transfer coefficient on the intermediate medium side in the intermediate medium evaporation section. For this reason, in a water cooling part, compared with an intermediate medium evaporation part, it becomes difficult for the temperature of a heat transfer tube wall to become low. Therefore, according to the liquefied natural gas vaporizer according to the above 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., it is possible to suppress icing in the vaporizer.

The liquefied natural gas vaporizer further comprises a natural gas warming unit for heating the natural gas by exchanging heat between the natural gas that has heat-exchanged with the water in the water cooling unit and the water before flowing into the intermediate medium evaporation unit. You can do it.

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

The cold water supply method according to the above embodiment is a method of supplying the water flowing out from the water cooling part of the liquefied natural gas vaporizer as cooling water for air for driving a gas turbine in a gas turbine combined power generator.

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 unit. For this reason, since the water content of air becomes low, combustion efficiency improves, and as a result, the power generation efficiency in a gas turbine combined power generator can be improved.

Claims (3)

It is a liquefied natural gas vaporizer,
An intermediate medium evaporator for evaporating at least a part of the liquid intermediate medium by exchanging heat between the liquid intermediate medium and water;
A liquefied natural gas evaporation unit for vaporizing at least a part of the liquefied natural gas by heat-exchanging the liquefied natural gas with the gaseous intermediate medium generated by evaporating the liquid intermediate medium in the intermediate medium evaporation unit;
By exchanging heat between the natural gas generated by vaporizing the liquefied natural gas in the liquefied natural gas vaporizing unit and the water cooled by heat exchange with the liquid intermediate medium in the intermediate medium evaporation unit through a heat transfer unit, the water A liquefied natural gas vaporizer with a water cooling unit for further cooling. The method of claim 1, further comprising a natural gas warming unit for heating the natural gas by exchanging heat between the natural gas that has exchanged heat with the water in the water cooling unit and the water before flowing into the intermediate medium evaporation unit. , liquefied natural gas vaporizer. A cold water supply method in which the water flowing out from the water cooling unit of the liquefied natural gas vaporizer according to claim 1 or 2 is supplied as cooling water for air for driving a gas turbine in a gas turbine combined power generator.

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