JPH08209158A - Apparatus for evaporating lng and evaporation - Google Patents

Abstract

PURPOSE: To provide an LNG-evaporating apparatus which dispenses with a large-scale apparatus for dealing with ultrapeaks, requires a low initial cost, and can be run at a low operating cost by installing the first heating medium circuit passing through a heat recovery apparatus, which recovers heat from a heat supply medium, and a heat storage apparatus, and the second heat medium circuit passing through the heat storage apparatus and an LNG evaporator. CONSTITUTION: A fluid contg. heat to be recovered (e.g. a gas such as an exhaust combustion gas from a gas turbine for power generation) is introduced through a line 7 into an exhaust heat recovery apparatus 1 where heat is transferred from the fluid to the first heat medium (e.g. water) circulated by a pump through the first heat medium circuit 11. Heat recovered in the circuit 11 is at least partly transferred at a heat storage apparatus 3 from the first heat medium to the second heat medium (e.g. ethylene glycol) circulated by a pump through the second heat medium circuit 19. The storage apparatus 3 balances the amt. of exhaust heat with the amt. of heat of evaporation of LNG. An evaporated LNG is taken out through a line 23.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an LNG vaporizer and vaporization method.

[0002]

2. Description of the Related Art Currently, natural gas is imported to Japan in a liquefied state (as LNG) and, after being vaporized, is widely used as city gas, industrial fuel gas, fuel gas for power generation, etc. ing.

The LNG vaporizer can be roughly classified into two types according to the vaporization heat source.

One of them is a vaporizer of the type that uses seawater as a heat source, and this type of vaporizer is further divided into an open rack type vaporizer (hereinafter referred to as ORV) and an intermediate heat medium type vaporizer. . This type of vaporizer is highly economical and has a large track record for large capacity base loads.

Another type is a vaporizer (submerged combustion type vaporizer; hereinafter referred to as SMV) of a type in which natural gas itself is burned in water and the resulting hot water is used as a heat source.
Say. ), High thermal efficiency, and rapid heating are possible, so it has a track record for peak shaving and emergency.

[0006] Further, an exhaust heat recovery type L that recovers heat from high temperature turbine exhaust gas by a heat medium passing through a circulation line and transfers the recovered heat to LNG via a heat exchanger.
An NG vaporizer has also been proposed (Japanese Patent Publication No. 6-70233).
No.).

However, the above three types of LNG
Each vaporizer has the following problems.

(A) Most of the plants and bases (mainly including storage tanks, vaporizers, etc.) that handle LNG are installed adjacent to the coast, and therefore seawater is used as a vaporizer for base load. Although an ORV and an intermediate heat medium vaporizer having a heat source as a heat source have been used, seawater may not be used as a heat source in the inland area depending on the location conditions.

(B) On the other hand, for SMV which does not use seawater as a heat source, when it is used as a carburetor for base load, fuel such as LNG, which is expensive, is used. Then, there is a problem that a large amount of fuel cost is required.

(C) Further, in the exhaust heat recovery type LNG vaporizer, the amount of exhaust heat and the amount of heat necessary for vaporizing LNG (hereinafter sometimes referred to as LNG vaporization heat amount) may change in a correlated manner. If there is a periodic fluctuation in the heat quantity difference between the exhaust heat quantity and the LNG vaporization heat quantity, and the time average value is zero, the turbine and heat exchanger, etc. must be designed to handle the peak value. Therefore, the initial cost is high. In addition, there is a case where the engine must be operated in a state deviating from the optimum design condition (for example, at the time of peak demand of gas), and there is a drawback that the operation efficiency of the device itself is reduced.

For example, in the case of city gas business, LN
At the G handling base, LNG is vaporized according to the city gas demand that fluctuates significantly during the day, day and season, so it is necessary to install a large LNG vaporization facility that can meet the maximum demand for natural gas. There is. Therefore, it is necessary to design the equipment based on the peak value in the evening in winter,
There are drawbacks such as low annual operating rate of equipment and high initial cost.

(D) Furthermore, the treatment of boil-off gas (BOG) from the LNG tank is also a problem. That is, from the LNG tank at the base handling LNG, a small amount of LNG is always vaporized due to heat input from the surroundings to generate BOG. Because of the low pressure of this gas, it must be returned to the gas delivery line using a compressor, which requires a great deal of power to drive the compressor. It is conceivable to use BOG as the fuel for the turbine and use the resulting power to drive the compressor, but while BOG is constant over time, the exhaust heat to be used for LNG vaporization is However, since it fluctuates, it is not possible to effectively use all the exhaust heat of the turbine.

[0013]

Therefore, the present invention can solve or alleviate the problems of the LNG vaporization technology by the conventional ORV, intermediate heat medium vaporizer, SMV, exhaust heat recovery type vaporizer and the like. The main object of the present invention is to provide a vaporization device and a vaporization method for LNG.

[0014]

The present inventor has conducted research while paying attention to the problems of the prior art as described above, and as a result, high temperature combustion exhaust gas from a gas turbine or the like (hereinafter sometimes referred to as heat source). When LNG is vaporized by utilizing the heat obtained from the above and the latent heat due to solidification / melting of the heat storage material, the difference in the calorific value between the exhaust heat quantity and the LNG vaporization heat quantity changes periodically without using seawater. It has been found that even when the time average value is zero, an LNG vaporization device and an LNG vaporization method having low initial costs such as equipment costs, low operating costs such as fuel costs, and high operating efficiency can be obtained.

That is, the present invention provides the following LNG vaporizing apparatus and LNG vaporizing method; A first heat medium circulation circuit that passes through a heat recovery device and a heat storage device for performing exhaust heat recovery from a heat supply body that passes through an exhaust heat supply line, and a second heat medium circulation that passes through the heat storage device and an LNG vaporizer. LNG vaporizer equipped with a circuit.

2. In the LNG vaporization method, (1) a step of recovering the heat from the exhaust heat supply line by the heat medium in the exhaust heat recovery device in the first heat medium circulation circuit passing through the exhaust heat recovery device and the heat storage device; ) In the heat storage device, the first heat medium circulation circuit, and the second heat medium circulation circuit that passes through the heat storage device and the LNG vaporizer, at least a part of the heat recovered in the step (1) above is used as the second heat medium circulation circuit. In addition to transferring heat to the heat medium in the heat medium circulation circuit, if the LNG vaporization heat amount is greater than the recovered exhaust heat amount, part of the LNG vaporization heat is stored in the heat storage material of the heat storage device in the form of latent heat of solidification, and LNG vaporization is performed. When the amount of heat is less than the amount of recovered exhaust heat, the solidification latent heat stored by the heat storage device is melted by the heat storage material,
A step of transferring cold heat to the heat medium of the first heat medium circulation circuit; and (3) a step of transferring heat of the heat medium of the second heat medium circulation circuit to the LNG in the LNG vaporizer. A characteristic LNG vaporization method.

The terms used in this specification are defined as follows.

"When LNG has a large amount of heat of vaporization" means LN
This is a case where the amount of heat required for vaporizing G is larger than the amount of exhaust heat.

"When LNG has a small amount of heat of vaporization" means L
It refers to the case where the amount of heat required to vaporize NG is less than the amount of exhaust heat.

Further, "exhaust heat" means heat contained in exhaust gas which is cheaper than heat obtained by combustion of LNG or the like, and is, for example, inexpensive obtained from a complex close to LNG vaporization equipment. Means heat.

The LNG vaporizing apparatus and the LNG vaporizing method according to the present invention will be described in more detail with reference to the flowcharts shown in the drawings.

The LNG vaporizer shown in FIG. 1 has an exhaust heat recovery device 1, a heat storage device 3 and an LNG vaporizer 5 as main constituent elements. The first heat medium circulation circuit 11 passes through the exhaust heat recovery device 1 and the heat storage device 3, and the second heat medium circulation circuit 19 passes through the heat storage device 3 and the LNG vaporizer 5.

A fluid containing exhaust heat to be recovered (for example, gas such as combustion exhaust gas from a gas turbine for power generation, liquid recovering exhaust heat, etc.) is introduced into the exhaust heat recovery apparatus 1 through a line 7. , A heat medium circulating and flowing in the first heat medium circulating circuit 11 by a pump (not shown) (hereinafter, the heat medium circulating and flowing in the first heat medium circulating circuit 11 is simply referred to as “first heat medium”). Sometimes called "medium"). The first heat medium is water or a eutectic mixture of an organic compound and an inorganic compound (for example, Na ₂ SO ₄ 31%, N 2
13% of aCl, 16% of KCl and 40% of H ₂ O) are exemplified, and water is more preferable among them.

The heat transfer in the exhaust heat recovery apparatus 1 may be performed by indirect heat exchange, or when the heat supply body is a high temperature gas (for example, exhaust gas), the gas is changed to water as a heat medium. You may mix and heat-transfer directly. However, in the latter case, it is necessary to install a gas-liquid separator (not shown) that separates gas and water.

The heat-recovered fluid or the heat-recovered gas-liquid separated gas phase is taken out of the system through the line 15.

At least a part of the heat recovered in the first heat medium circulation circuit 11 is pumped in the heat storage device 3 via the first heat medium regardless of whether the LNG vaporization amount is large or small. A heat medium that circulates and flows in the second heat medium circulation circuit 19 (not shown) (hereinafter, a heat medium that circulates and flows in the second heat medium circulation circuit 19 is simply referred to as “second heat medium”). That is the case). The heat storage device 3 is not particularly limited, and heat is transferred between the first heat medium, the second heat medium, and the heat storage material (solidified or melted depending on the operating condition of the entire device). If it is possible, a general-purpose device can be used as it is.

In the present invention, the term "heat transfer from the first heat medium to the second heat medium" means that heat is transferred from the first heat medium to the heat storage material of the heat storage device 3, and It also includes the case where heat is transferred from the heat storage material to the second heat medium.

The heat storage device 3 contains water or a eutectic mixture similar to the above as a heat storage material. As the heat storage material, it is preferable to use water because it is easily available and has a large latent heat for heat storage. Further, as the second heat medium, at least one kind of alcohols such as ethylene glycol, methyl alcohol and ethyl alcohol, a mixture of at least one kind of these alcohols and water and the like are used. Of these, ethylene glycol is more preferable.

The heat transfer in the heat storage device 3 is performed between the first heat medium and the second heat medium, between the first heat medium and the solidified heat storage material, and between the melted heat storage material and the second heat medium. It is carried out with the medium respectively.

In the LNG vaporizer 5, heat exchange is performed between the LNG and the second heat medium. By this heat exchange, the second heat medium that has become sufficiently low temperature takes heat from the heat storage material in the heat storage device 3 and solidifies the liquid heat storage material, so that the latent heat of solidification (heat storage material is In the case of water, a part of the LNG vaporization heat is stored as cold heat in the form of ice solidification latent heat).

When the LNG vaporization heat amount is large, almost all of the exhaust heat recovered in the first heat medium circulation circuit 1 is
The heat is transferred to the second heat medium and the LNG line 21
The cold heat transferred from the LNG passing through to the second heat medium is transferred to the liquid heat storage material in the heat storage device 3 to solidify the heat storage material into a solid.

On the contrary, when the LNG heat of vaporization is small,
A part of the exhaust heat recovered in the first heat medium circulation circuit 1 is transferred to the second heat medium, and the rest of the exhaust heat recovered in the first heat medium circulation circuit 1 is transferred in the heat storage device 3. By transferring heat to a solid heat storage material, the heat storage material is melted to form a liquid. In this way, when the LNG vaporization amount becomes large, the required LNG vaporization heat can be stored in the heat storage material in the heat storage device 3 in the form of latent heat of solidification.

Regardless of whether the amount of heat of vaporization of LNG is large or small, the LNG vaporizer 5 exchanges heat between the second heat medium and LNG, whereby the LN is removed from the second heat medium.
The heat transfer to G makes it possible to vaporize LNG.

Thus, the heat storage device 3 stores heat by solidifying the heat storage material when the amount of LNG vaporization heat is large, and melts the solidified heat storage material when the amount of LNG vaporization heat is small. The amount of exhaust heat and the amount of heat of vaporization of LNG can be balanced.

The vaporized natural gas passes through the line 23,
If necessary, the after heater 25 heats the temperature from below 0 ° C. to above 0 ° C. This is LNG in the soil
This is done to prevent freezing of water in the soil that contacts the delivery line. The heating of natural gas in the after heater 25
Indirect heat exchange may be performed using a part of the heat source fluid from the line 7 or using a heat source fluid taken out of the system from the line 15 after heat recovery in the heat recovery apparatus 1. When indirect heat exchange is performed, the systems can be made independent of each other, which facilitates design and operation.

As the heat medium in the first heat medium circulation circuit, a part of the heat storage material in the heat storage device 3 may be used in liquid form. In this case, since the exhaust heat recovered by the first heat medium can be directly transferred to the heat storage material, there is an advantage that the heat efficiency at the time of heat exchange becomes high.

The apparatus of the present invention shown in FIG.
7 is installed side by side, and the combustion exhaust gas from the gas turbine is sent to the exhaust heat supply line 7. The gas turbine 27
A type in which boil-off gas from LNG is used as a fuel and which is connected to a generator G to generate electric power is particularly preferable. As a heat source of the after-heater 25, combustion exhaust gas from the gas turbine after exhaust heat recovery is used.

According to the embodiment of the present invention shown in FIG. 2, since the BOG of LNG is used as the fuel of the gas turbine and the combustion exhaust gas of the inexpensive gas turbine is used as the heat source, the BOG is boosted by the compressor or the like. However, there is no need to send it out as city gas. Further, the electric power obtained by the generator G can be effectively used as a power source of the LNG base or the surplus as commercial electric power.

Instead of a combination of a gas turbine and a generator, a combination of a gas engine and a generator,
Alternatively, a fuel cell or the like may be used as the heat source.

FIG. 3 is a drawing showing in detail an example of the heat storage device 3 used in the present invention.

The pre-heat exchanger 29 in the heat storage device 3 serves to transfer at least a part of the exhaust heat recovered in the first heat medium circulation circuit 11 to the heat medium in the second heat medium circulation circuit 19. Have. Further, the heat storage tank 31 stores heat by the heat storage material contained therein. In the heat storage device 3, a control valve (not shown) is used to divide the heat medium in the first heat medium circulation circuit 11 so that the heat medium flows in parallel in the line 11a and the line 11b. The amount of heat supplied to the pre-heat exchanger 29 and the amount of heat supplied to the heat storage tank 31 can be appropriately distributed. As a result, LNG
Since only a required amount of the exhaust heat for vaporization can be transferred to the second heat medium, the heat transfer efficiency in the heat storage device 3 becomes high,
It is also possible to improve the operation efficiency of the entire LNG vaporizer.

In the same manner as in the first heat medium circulation circuit 11, the heat medium in the second heat medium circulation circuit 19 is diverted by the control valve (not shown) in the heat storage device 3. The second heat medium amount supplied to the pre-heat exchanger 29 and the second heat medium amount supplied to the heat storage tank 31 are configured to flow in parallel in the line 19a and the line 19b. It can be adjusted appropriately.

As a result, when the amount of heat of vaporization of LNG is larger than the amount of heat of exhaust, almost all the amount of the first heat medium passes through the line 11b and the pre-heat exchanger 29 is controlled by the control valve.
LNG vaporizer 5 (see FIGS. 1 and 2)
And is transferred to the second heat transfer medium passing through the line 19b. On the other hand, by the control of the control valve, the second heat medium is sent to the pre-heat exchanger 29 through the line 19b in an amount commensurate with the amount of exhaust heat to be transferred to the first heat medium, and at the same time, to the second heat medium. The rest of the medium is sent to the heat storage tank 31 through the line 19a to solidify the heat storage material and store cold heat in the form of solidification latent heat.

When the amount of heat of vaporization of LNG is smaller than the amount of heat of exhaust, almost all the amount of the second heat medium is fed into the pre-heat exchanger 29 through the line 19b and passes through the line 11b by the control of the control valve. Heat is transferred from the first heat medium. On the other hand, the first heat medium is controlled by the control valve so that only the amount corresponding to the LNG vaporization heat amount is equal to the pre heat exchanger 29.
And is transferred to the second heat medium. The rest of the first heat medium is sent to the heat storage tank 31 through the line 19a,
The solidified heat storage material is melted.

Since the heat storage device 3 has the structure shown in FIG. 3, the heat exchange efficiency is improved, so that the operation efficiency of the entire LNG vaporizer is increased. Further, since the temperature of the second heat medium can be made relatively high, the effect that the size of the LNG vaporizer can be made small is also achieved.

As described above, in the city gas business, the daily demand fluctuation of natural gas (NG) is extremely large. For example, although specific values may differ depending on regions, in winter, the ratio of NG demand between the maximum demand time zone (Ultra Peak) around 8:00 pm and the minimum demand time zone around 4:00 am is It may reach up to 3: 1. Conventionally, in order to cope with such a large demand fluctuation, it has always been necessary to install a large-scale LNG vaporizer equipped with a large-sized gas turbine corresponding to the maximum demand time zone, an exhaust heat recovery boiler, and the like. .

However, according to the present invention, when the LNG heat of vaporization is large, a solidified body (for example, ice) of the heat storage material is produced and cold heat is stored in the form of latent heat of solidification. On the other hand, when the amount of heat of vaporization of LNG is small, the solidified body of the heat storage material is melted by exhaust heat and the stored heat of vaporization of LNG is recovered. In this way, the LNG vaporization heat amount and the exhaust heat amount can be balanced by periodically repeating the solidification and melting of the heat storage material, so that the entire LNG vaporization equipment can be downsized. Such an effect of the present invention is not limited to the city gas business, and is achieved even when the heat quantity difference between the LNG vaporization heat quantity and the exhaust heat quantity fluctuates periodically and the time average is almost zero.

[0048]

EFFECTS OF THE INVENTION By installing a heat storage device in the LNG vaporizer, the difference between the LNG vaporization heat quantity and the exhaust heat quantity fluctuates periodically, and even when the time average becomes almost zero, such fluctuations occur. Since it can be absorbed, it is not necessary to install a large-scale facility corresponding to Ultra Peak, the initial cost is low, and the operating cost is low.
A G vaporization method is obtained.

Since the use of the heat storage device can absorb the fluctuation of the heat quantity difference, it is possible to operate the turbine, which is the exhaust heat supply source, with a constant capacity, and the exhaust heat recovery device can also be operated with a constant capacity. Therefore, if the optimum design corresponding to such a constant capacity is performed, the turbine and the exhaust heat recovery device can be operated efficiently, and the operation efficiency of the entire LNG vaporization facility can be improved.

When recovering the exhaust heat of the turbine or the like,
By using the BOG generated in the LNG tank as fuel for the turbine or the like, it is not necessary to pressurize the BOG with a compressor or the like and send it out as city gas.

Since seawater is not required as a heat source, LNG vaporizing equipment can be installed in the inland area.

[0052]

EXAMPLES Examples are shown below to further clarify the features of the present invention.

Example 1 LNG is vaporized by using the system shown in FIG.
At this time, the amount of heat supplied to the exhaust heat recovery apparatus 1 by the heat source fluid is constant throughout the day, and ethylene glycol as the second heat medium enters the LNG vaporizer 5 at -2 ° C and exits at -38 ° C. Control the flow rate of the heat source fluid.

In the LNG vaporizer 5, the ethylene glycol supplied at -2 ° C and the LNG at -150 ° C are heat-exchanged to obtain NG at -30 ° C and ethylene glycol at -38 ° C.

On the other hand, a gas turbine (not shown) is driven by using the obtained boil-off gas from the NG or LNG tank as fuel to generate electric power and exhaust gas (heat source fluid) at 500 ° C.
At the same time, the exhaust gas is guided to the exhaust heat recovery apparatus 1 to obtain hot water of 140 ° C. as the first heat medium.

The above-mentioned -2 ° C ethylene glycol and 14
When hot water of 0 ° C. is used and the load of ethiglycol is larger (when the exhaust heat is less), the water is solidified in the heat storage device 3 and when the load of the hot water is larger (the exhaust heat is larger). If), thaw the ice.

According to this process, the load fluctuation of LNG can be absorbed by using the heat storage device 3 and the gas turbine together. Moreover, when BOG is used as fuel for the gas turbine, compressor power for gas delivery can be saved.

[Brief description of drawings]

FIG. 1 is a flow chart showing an embodiment of the apparatus used in the present invention and the method of the present invention.

FIG. 2 is a flowchart showing an embodiment in which a gas turbine is additionally provided in the apparatus shown in FIG.

FIG. 3 is a flowchart showing an outline of an operating condition of the heat storage device according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Exhaust heat recovery device 3 ... Heat storage device 5 ... LNG vaporizer 7 ... Exhaust heat supply line 11 ... First heat medium circulation circuit 19 ... Second heat medium circulation circuit 21 ... LNG supply line 23 ... Natural gas line 25 … After-heater 27… Gas turbine 29… Pre-heat exchanger 31… Heat storage tank

Claims (26)

[Claims] 1. A first heat medium circulation circuit passing through a heat recovery device for recovering exhaust heat from a heat supply body passing through an exhaust heat supply line and a heat storage device, and a first heat medium circulation circuit passing through the heat storage device and an LNG vaporizer. An LNG vaporizer having a second heat medium circulation circuit. 2. The heat medium in the first heat medium circulation circuit is water or a eutectic mixture of an organic compound and an inorganic compound.
The LNG vaporizer according to 1. 3. The LNG vaporizer according to claim 1, wherein the heat recovery from the heat supply body to the heat medium in the exhaust heat recovery apparatus is performed by indirect heat exchange. 4. The heat supply in the exhaust heat recovery apparatus is a gas, and the gas is mixed with the heat medium of the first heat medium circulation circuit to directly transfer heat to the heat medium and then to form a gas. The LNG vaporization device according to claim 1 or 2, which separates the heat medium from the liquid. 5. The LNG vaporizer according to claim 1, wherein the heat storage material in the heat storage device is water or a eutectic mixture of an organic compound and an inorganic compound and stores heat in the form of latent heat of solidification. 6. The LNG vaporizer according to claim 1, wherein the heat medium of the first heat medium circulation circuit is water, and a part of water which is a heat storage material is used as the water. 7. The L according to claim 1, wherein the heat medium of the second heat medium circulation circuit is ethylene glycol.
NG vaporizer. 8. The LNG vaporizer according to claim 1, wherein the heat medium in the second heat medium circulation circuit is alcohol or a mixture of alcohol and water. 9. The LNG vaporizer according to claim 1, wherein the heat supply in the exhaust heat recovery device is exhaust gas from a gas turbine, and the gas turbine uses boil-off gas of LNG as fuel. 10. The L according to claim 1, wherein the heat storage device includes a pre-heat exchanger and a heat storage tank.
NG vaporizer. 11. The LNG vaporizer according to claim 1, further comprising an after-heater for heating natural gas obtained by vaporizing LNG. 12. The LNG vaporizer according to claim 1, wherein a part of the heat supply medium passing through the exhaust heat supply line is used as the heat source of the afterheater. 13. The LNG vaporizer according to claim 11, wherein the after-heater is an indirect heating type heater. 14. In the LNG vaporization method, (1) in a first heat medium circulation circuit that passes through an exhaust heat recovery device and a heat storage device, heat from an exhaust heat supply line is recovered by a heat medium in the exhaust heat recovery device. In the step (2), the heat storage device, the first heat medium circulation circuit, and the second heat medium circulation circuit that passes through the heat storage device and the LNG vaporizer, at least one of the heat recovered in the process (1) above. Part is transferred to the heat medium of the second heat medium circulation circuit, and when the LNG vaporization heat amount is larger than the recovered exhaust heat amount, a part of the LNG vaporization heat is transferred to the heat storage material of the heat storage device in the form of solidification latent heat. When the amount of heat of vaporization of LNG is smaller than the amount of recovered exhaust heat, the latent heat of solidification stored by the heat storage device is melted in the heat storage material to transfer cold heat to the heat medium of the first heat medium circulation circuit. Process,
And (3) the heat of the heat medium of the second heat medium circulation circuit is LN
A method for vaporizing LNG, comprising a step of transferring heat to LNG in a G vaporizer. 15. The G vaporization method for LN according to claim 14, wherein the heat medium in the first heat medium circulation circuit is water or a eutectic mixture of an organic compound and an inorganic compound. 16. The method for vaporizing LNG according to claim 14, wherein the heat recovery from the heat supplier to the heat medium in the exhaust heat recovery device is performed by indirect heat exchange. 17. The heat supply body in the exhaust heat recovery apparatus is a gas, and the gas is mixed with the heat medium of the first heat medium circulation circuit to directly transfer heat to the heat medium and then to form the gas. The L according to claim 14 or 15, which is gas-liquid separated from a heat medium.
NG vaporization method. 18. The L according to claim 14, wherein the heat storage material in the heat storage device is water or a eutectic mixture of an organic compound and an inorganic compound and stores heat in the form of latent heat of solidification.
NG vaporization method. 19. The method for vaporizing LNG according to claim 14, wherein the heat medium of the first heat medium circulation circuit is water, and a part of water which is a heat storage material is used as the water. 20. The method for vaporizing LNG according to claim 14, wherein the heat medium in the second heat medium circulation circuit is ethylene glycol. 21. The heat medium of the second heat medium circulation circuit is alcohol or a mixture of alcohol and water.
21. The method for vaporizing LNG according to any one of 20 to 20. 22. The method for vaporizing LNG according to claim 14, wherein the heat supply body in the exhaust heat recovery apparatus is exhaust gas from a gas turbine, and the gas turbine uses boil-off gas of LNG as fuel. 23. The method for vaporizing LNG according to claim 14, wherein the heat storage device comprises a pre-heat exchanger and a heat storage tank. 24. The method for vaporizing LNG according to claim 14, wherein the natural gas obtained by vaporizing LNG is heated by an after-heater. 25. The method for vaporizing LNG according to claim 24, wherein a part of the heat supply medium passing through the exhaust heat supply line is used as a heat source of the afterheater. 26. The method for vaporizing LNG according to claim 24, wherein the after-heater is an indirect heating type heater.