WO2018078715A1

WO2018078715A1 - Liquefied natural gas storage facility

Info

Publication number: WO2018078715A1
Application number: PCT/JP2016/081553
Authority: WO
Inventors: 秀二大橋; 安達　修; 篤志神谷; 嘉朗外池
Original assignee: 日揮株式会社; 住友精密工業株式会社
Priority date: 2016-10-25
Filing date: 2016-10-25
Publication date: 2018-05-03

Abstract

[Problem] To provide a liquefied natural gas storage facility provided with a submerged liquefied natural gas vaporizer (SMV) that can make efficient use of waste heat from a gas engine. [Solution] A natural gas storage facility is provided with a gas engine 3 for driving a power generator 31 and uses an SMV 2 to vaporize liquefied natural gas. In the SMV 2, when engine exhaust gas from the gas engine 3 and burner exhaust gas from a burner 231 are used to vaporize the liquefied natural gas, the amounts of engine exhaust gas and burner exhaust gas to be introduced to water W in a water tank 20 of the SMV 2 are adjusted in a manner corresponding to the flow rate of liquefied natural gas determined on the basis of a pressure measurement result for a product gas containing vaporized natural gas.

Description

Liquefied natural gas storage equipment

The present invention relates to a technique for vaporizing liquefied natural gas using a submerged liquefied natural gas vaporizer.

Natural gas produced at the well of the gas field is cooled, liquefied and stored in a storage tank (LNG tank) as liquefied natural gas (LNG), then gasified again and demanded via the pipeline Supplied first.

Known devices that vaporize LNG sent from LNG tanks include open rack LNG vaporizers that use seawater to vaporize LNG, and submerged liquefied natural gas vaporizers (SMVs). It has been.
SMV arranges a heat exchange tube through which LNG flows in a water tank filled with water, introduces burner exhaust gas obtained by burning fuel with a burner into water, and heats the water heated by the burner exhaust gas. LNG is vaporized by heat exchange.

SMV has the advantage that it does not require large-scale facilities such as a seawater supply system, and is small in size and low in initial costs, as compared with an open rack type LNG vaporizer. On the other hand, since SMV requires fuel for obtaining burner exhaust gas, there is room for improvement in terms of running cost.

Here, Patent Document 1 describes an SMV type LNG vaporizer that includes a small burner and a mechanism that introduces high-temperature exhaust gas obtained from a heat-generating power generation device that generates power using LNG as fuel into a hot water bath chamber. ing. However, Patent Document 1 does not disclose specific technical contents for utilizing burner exhaust gas and high-temperature exhaust gas in combination in order to realize stable shipment of product gas including vaporized natural gas.

JP 2002-168149 A

The present invention has been made under such a background, and an object thereof is to provide a liquefied natural gas storage facility equipped with an SMV capable of effectively utilizing exhaust heat of a gas engine. .

The liquefied natural gas storage facility of the present invention is a liquefied natural gas storage facility that vaporizes liquefied natural gas stored in a storage tank and then discharges it to the outside.
A gas engine that drives the generator;
A submerged liquefied natural gas vaporizer that vaporizes liquefied natural gas supplied from the storage tank, and
The submerged liquefied natural gas vaporizer is
A water tank in which water is stored;
A liquefied natural gas supply line that is arranged so as to be immersed in water in the water tank and that is supplied with liquefied natural gas from the storage tank, and for discharging the vaporized natural gas obtained by vaporizing the liquefied natural gas A vaporizer for heating and vaporizing the liquefied natural gas flowing through the heat exchange tube by heat exchange with the water in the water tank.
Introduction of engine exhaust gas for introducing engine exhaust gas received through an exhaust gas supply line to which engine exhaust gas is supplied from the gas engine into the water in the water tank and supplying combustion exhaust heat of the gas engine to the water And
A burner that mixes fuel and air to burn the fuel, a fuel supply unit that supplies fuel to the burner, a blower unit that supplies air, and a fuel burned by the burner A burner exhaust gas for introducing the burner exhaust gas into the water in the water tank and supplying the heat of combustion of the fuel to the water, and
Furthermore, an engine exhaust gas flow rate adjusting unit for adjusting a supply flow rate of engine exhaust gas from the gas engine to the engine exhaust gas introducing unit,
A burner load adjuster for adjusting the flow rate of fuel supplied to the burner;
A pressure measuring unit that is discharged from the discharge line and measures the pressure of the product gas including the vaporized natural gas;
A liquid feed flow rate adjusting unit that adjusts the flow rate of the liquefied natural gas supplied to the liquefied natural gas vaporizer so that the pressure of the product gas measured by the pressure measuring unit approaches a preset target pressure; ,
The engine exhaust gas flow rate adjusting unit and the burner load adjusting unit are arranged so that the amount of heat necessary for vaporizing the liquefied natural gas at the flow rate adjusted by the liquid supply flow rate adjusting unit is supplied to the liquefied natural gas vaporizer. And an exhaust gas introduction control unit for adjusting an introduction amount of the engine exhaust gas and the burner exhaust gas into the water in the water tank.

The liquefied natural gas storage facility may have the following characteristics.
(A) A natural gas temperature measuring unit that measures the temperature of vaporized natural gas discharged from the liquefied natural gas vaporizer to a discharge line is provided, and the exhaust gas introduction control unit is vaporized measured by the natural gas temperature measuring unit Supplying the amount of heat necessary for the liquefied natural gas vaporizer by adjusting the amount of engine exhaust gas and burner exhaust gas introduced into the water in the water tank so that the temperature of the natural gas approaches a preset target temperature To do. Alternatively, a water temperature measuring unit that measures the temperature of water in the water tank is provided, and the exhaust gas introduction control unit is configured so that the temperature of the water measured by the water temperature measuring unit approaches a preset target temperature. Supplying the amount of heat required for the liquefied natural gas vaporizer by adjusting the amount of engine exhaust gas and burner exhaust gas introduced into the water in the tank.
(B) The fuel supply unit includes a fuel cut-off unit that performs supply and stop of fuel to the burner and switches the burner between a stopped state and an operating state, and the exhaust gas introduction control unit includes the natural gas The engine exhaust gas flow rate adjusting unit is used to adjust the supply flow rate of the engine exhaust gas to the engine exhaust gas introduction unit, and the engine exhaust gas flow rate adjusting unit is used to adjust the engine exhaust gas so that the necessary amount of heat is supplied by the vaporizer. If the liquefied natural gas vaporizer exceeds the capacity and needs heat, and the burner is stopped, the fuel supply unit is used to supply fuel from the fuel supply unit. And put the burner into operation.
(C) In (b), the exhaust gas introduction control unit is configured so that an introduction amount of engine exhaust gas and burner exhaust gas corresponding to the amount of heat necessary for the liquefied natural gas vaporizer is introduced into the water in the water tank. Then, when the fuel supply flow rate to the burner becomes a preset minimum flow rate, the fuel supply unit is used to stop the fuel supply from the fuel supply unit, and the burner is stopped. To switch. A bypass line that bypasses the engine exhaust gas introduction unit and exhausts the engine exhaust gas to the outside, and the exhaust gas introduction control unit has an introduction amount of engine exhaust gas corresponding to a heat amount required for the liquefied natural gas vaporizer. When engine exhaust gas larger than the supply flow rate of engine exhaust gas to the engine exhaust gas introduction part is exhausted from the gas engine and the burner is in a stopped state under the condition of being introduced into the water in the water tank Exhaust excess engine exhaust gas to the outside through the bypass line.
(D) The boil-off gas generated in the storage tank is used as the fuel gas of the gas engine.
(E) At least one of boil-off gas generated in the storage tank or liquefied petroleum gas is added to the product gas.

The present invention adjusts the flow rate of the liquefied natural gas supplied to the SMV based on the measurement result of the pressure of the product gas containing the vaporized natural gas, and the amount of heat necessary for vaporizing the liquefied natural gas at the flow rate is supplied. Thus, the introduction amount of the engine exhaust gas and the burner exhaust gas introduced into the water in which the heat exchange tube for vaporizing the liquefied natural gas is immersed is adjusted. As a result, the product gas can be stably shipped while the liquefied natural gas is vaporized using the engine exhaust gas of the gas engine.

It is a lineblock diagram of the LNG storage equipment concerning an embodiment of the invention. It is the vertical side view of SMV provided in the said LNG storage facility, and explanatory drawing of the peripheral device. It is a cross-sectional plan view of the SMV. It is a flowchart which shows the flow of the operation | movement which concerns on the said SMV. It is an effect | action figure which shows the change of the delivery pressure of product gas, etc. before and after burner ignition. It is a block diagram of the LNG storage facility which concerns on other embodiment.

First, the overall configuration of the LNG storage facility according to the present embodiment will be described with reference to FIG.
The LNG storage facility is configured, for example, as a receiving base that receives LNG from a liquefied natural gas (LNG) ship, a satellite base that receives LNG from a tank truck, and the like, and includes a storage tank 1 that stores LNG.

The storage tank 1 is connected to the SMV 2 via the

LNG supply lines

501a and 501b, and the LNG in the storage tank 1 is supplied to the SMV 2 using the LNG pump 11 and the delivery pump 12. The SMV 2 vaporizes LNG by heat exchange with the water W stored in the water tank 20, and discharges the obtained gas NG to the discharge line 502.

Also, in the storage tank 1, BOG (Boil Off Gas) is generated due to heat input from the outer wall, heat input at the time of LNG reception, liquid level change in the LNG tank, and the like. After this BOG is extracted from the LNG tank, the pressure is increased by, for example, the BOG compressor 4 including a plurality of

compression stages

401 and 402. The high pressure BOG after the pressure increase is mixed with the NG discharged from the SMV 2 to the discharge line 502. Furthermore, LPG for heat quantity adjustment is added to the NG after BOG mixing by the heat quantity adjustment unit 51, and shipped to the user as product gas. The gas mixed and added to the product gas may be either BOG or LPG.

Furthermore, in addition to mixing the BOG generated in the storage tank 1 with NG, the LNG storage facility of this example includes a gas engine 3 that drives the generator 31 by burning the BOG. The gas engine 3 of this example can be operated with a low pressure BOG having a lower pressure than the high pressure BOG mixed with NG. For example, the low pressure BOG is extracted from the discharge side of the intermediate stage of the BOG compressor 4 and supplied to the gas engine 3. The electric power obtained by driving the generator 31 by the gas engine 3 is supplied to equipment that consumes electric power in the LNG storage facility such as the BOG compressor 4, the LNG pump 11 and the delivery pump 12, and becomes surplus. Electric power may be sold to the outside.

In the gas engine 3, high temperature exhaust gas (engine exhaust gas) is generated by burning BOG. The SMV 2 provided in the LNG storage facility of this example has a configuration capable of vaporizing LNG using the heat of the engine exhaust gas.
Hereinafter, the configuration of the SMV 2 will be described with reference to FIGS.

As shown in FIGS. 2 and 3, the SMV 2 has a structure in which a plurality of heat exchange tubes 21 made of meandering pipes are immersed in a water tank 20 in which water W is stored. A manifold-like supply header 211 connected to the upstream end of these heat exchange tubes 21 is disposed at the bottom of the water tank 20. The supply header 211 is connected to the above-described LNG supply line 501 b through which the LNG from the storage tank 1 is sent, and the LNG is supplied to each heat exchange tube 21 via the supply header 211.

A manifold-like discharge header 212 connected to the downstream end of each heat exchange tube 21 is disposed at the upper position in the water tank 20. The payout header 212 is connected to the vaporized NG payout line 502, and the NG vaporized in each heat exchange tube 21 is collected in the payout header 212 and then discharged to the payout line 502. Here, the plurality of heat exchange tubes 21, the supply header 211, and the payout header 212 constitute a vaporizer of the SMV 2.

Further, the water tank 20 is provided with an engine exhaust gas introduction part 22 for introducing high-temperature engine exhaust gas received from the gas engine 3 side into the water W in the water tank 20.
The engine exhaust gas introduction unit 22 receives the engine exhaust gas at a position below the heat exchange tube 21 and a downcomer unit 22 a that is a pipe for guiding the engine exhaust gas received from the gas engine 3 to the lower side of the heat exchange tube 21. And a distributor 22b for dispersing and introducing into the water in the water tank 20.

As shown in FIG. 3, for example, the distributor 22 b has a plurality of pipes arranged at intervals in the horizontal direction along the bottom surface of the water tank 20, and the wall surfaces of these pipes along the extending direction of the pipes. A large number of discharge holes 221 are provided.

When the gas engine 3 is used, the engine exhaust gas acceptance pressure in the engine exhaust gas introduction part 22 is a pressure within a range of approximately 12 to 30 kPaG. At this time, in order to ensure sufficient contact time between the engine exhaust gas and the water W, the position of the engine exhaust gas introduced from the distributor 22b to the water W (discharge hole 221) and the water surface of the water W in the water tank 20 The height distance between them is preferably set to 1200 mm or more and less than the height of the water column corresponding to the receiving pressure.

In the engine exhaust gas introduction part 22 having the above-described configuration, the engine exhaust gas is supplied to each pipe of the distributor part 22b through the downcomer part 22a, and then, from each discharge hole 221 to the water W in the water tank 20. Hot engine exhaust is introduced. As a result, the engine exhaust gas becomes bubbles and rises in the water, and heat energy is supplied by heat exchange accompanying contact between the water W and the engine exhaust gas.

When the LNG flowing in the heat exchange tube 21 is vaporized, heat is removed from the water W in the water tank 20 by the heat of vaporization, so that heat necessary for vaporizing LNG can be replenished by introducing high-temperature engine exhaust gas.
The bubbles of the engine exhaust gas that has risen in the water are discharged from the water surface and then exhausted to the outside through the exhaust unit 201 provided on the upper surface side of the water tank 20.

Further, as shown in FIGS. 2 and 3, the SMV 2 of this example is provided with a burner 231 that assists in heating the water W in the water tank 20 by engine exhaust gas. The burner 231 of this example uses, as fuel, the product gas after the calorific value extracted from the discharge line 502 via the fuel supply line 503. In the burner 231, the fuel supplied from the fuel supply line 503 is mixed with the air supplied from the blower unit 24 and burned, whereby high-temperature burner exhaust gas is obtained. At this time, a configuration is adopted in which a part of the air supplied from the blower 24 is directly introduced into the water W in the water tank 20 without being used for combustion in the burner 231 according to the load of the burner 231. May be.

On the outlet side of the burner 231, a burner exhaust gas introduction part 234 including a downcomer part 234a and a distributor part 234b for introducing the burner exhaust gas to the water W in the water tank 20 is provided. The configuration of the burner exhaust gas introduction unit 234 and the behavior of the burner exhaust gas introduced into the water from here are almost the same as in the case of the engine exhaust gas introduction unit 22 described above, and thus the description thereof is omitted.

Next, a configuration example of the control mechanism of SMV2 will be described.
The SMV 2 in this example adjusts the discharge flow rate of NG from the SMV 2 so that the pressure of the product gas shipped from the discharge line 502 to the user is maintained at the target pressure.

In the transport of the product gas through the pipeline, the product gas shipping pressure from the payout 502 line is set so that the user can consume the product gas at the required flow rate. Therefore, if the delivery flow rate of NG is adjusted so that the delivery pressure of the product gas from the delivery line 502 is maintained at the target pressure, a necessary amount of product gas can be supplied to the user.

Therefore, as shown in FIG. 2, a product gas pressure gauge (pressure) for measuring the shipping pressure of the product gas is provided in the discharge line 502 downstream of the BOG and LPG mixing / addition position and the branch position of the fuel supply line 503. Measurement unit) 522 is provided. From the storage tank 1 side using the LNG supply amount adjusting unit (liquid feed flow rate adjusting unit) 521 so that the product gas shipping pressure measured by the product gas pressure gauge 522 approaches the preset target pressure. LNG supply flow rate is adjusted. The LNG supply amount adjusting unit 521 is provided with an LNG flow meter 522 that measures the supply flow rate of LNG supplied to the SMV 2.

When the LNG is supplied to the SMV 2 by the above-described method, the specific amount of LNG or the latent heat of vaporization of the LNG due to a small amount of introduction of engine exhaust gas or burner exhaust gas introduced into the water W in the water tank 20 or component change Or the temperature of NG discharged to the payout line 502 decreases. If the addition amounts of BOG and LPG are constant, the temperature of the product gas shipped from the payout line 502 to the user is eventually lowered.

Further, if the water W in the water tank 20 does not have a sufficient amount of heat to vaporize the LNG supplied from the LNG supply line 501b and raise it to a predetermined temperature, the pressure drop of NG discharged to the discharge line 502 There is also a risk of incurring.

Therefore, in order to confirm that the amount of heat necessary for vaporizing the LNG supplied to the SMV 2 is supplied from the engine exhaust gas or the burner exhaust gas, for example, a discharge NG thermometer ( Natural gas temperature measuring unit) 531 is provided. Then, by using a bypass valve 321 and a fuel gas flow rate control valve 261 described later, the exhaust gas of the engine and the burner exhaust gas are used so that the temperature of the NG gas measured by the dispensing NG thermometer 531 approaches a preset target temperature. Adjust the amount introduced.

Further, as shown in FIG. 2, the exhaust gas supply line 504 is provided with a supply flow meter 323 for measuring the flow rate of the engine exhaust gas supplied from the gas engine 3 to the SMV 2. An exhaust gas supply line 504 branches off a bypass line 505 that bypasses the engine exhaust gas introduction unit 22 and discharges excess engine exhaust gas to the outside.

The bypass line 505 is provided with a bypass valve 321 for increasing or decreasing engine exhaust gas discharged to the bypass line 505 side, and a bypass flow meter 324 for measuring the flow rate of engine exhaust gas discharged to the bypass line 505 side. ing. The bypass line 505 and the bypass valve 321 constitute an engine exhaust gas flow rate adjustment unit.

Further, as shown in FIG. 2, the fuel supply line 503 for supplying fuel to the burner 231 is provided with a fuel gas flow rate adjusting valve 261 for adjusting the fuel supply flow rate to the burner 231. The fuel gas flow rate adjustment valve 261 constitutes a burner load adjustment unit. Further, the fuel gas flow rate adjustment valve 261 also has a function as a fuel supply / cutoff section. In addition to the fuel gas flow rate adjustment valve 261, it is needless to say that a shut-off valve constituting a fuel supply / cutoff section may be provided.

2 adjusts the load of each exhaust gas so as to adjust the temperature of NG gas by adjusting the introduction amount of at least one of engine exhaust gas and burner exhaust gas. In the LNG storage facility of this example, the load adjustment unit 532 vaporizes LNG by preferentially using engine exhaust gas, and vaporizes LNG supplied from the LNG supply line 501b side. In such a case, the load is distributed so that the burner 231 is operated.

The setting of the regulation of the introduction amount of the engine exhaust gas and the burner exhaust gas via the load adjusting unit 532 is performed using, for example, a computer system that performs overall control of the entire LNG storage facility. In this respect, the computer system corresponds to the exhaust gas introduction control unit 6 for adjusting the amount of engine exhaust gas or burner exhaust gas introduced into the water W stored in the water tank 20. Further, the load adjusting unit 532 described above also constitutes a part of the exhaust gas introduction control unit.

Furthermore, the burner exhaust gas introduction part 234 is provided with a thermometer (not shown) for measuring the temperature of the burner exhaust gas introduced into the water W in the water tank 20. In addition, for the BOG and LPG mixed and added to NG and the product gas after these BOG and LPG are mixed and added, a flow meter (not shown) for measuring the flow rate of each fluid may be provided.

The operation of the operation of vaporizing LNG using the SMV 2 described above will be described.
4 to 5 show an example of an operation of switching the burner 231 that is normally in a stopped state between the operating state. At this time, it is assumed that the engine exhaust gas calorific value discharged from the gas engine 3 is in a surplus balance with the burner 231 stopped. In this case, the shipping pressure of the product gas measured by the product gas pressure gauge 522 is a preset target pressure (FIG. 5A), and surplus engine exhaust gas passes through the bypass line 505. Are discharged to the outside.

Consider a case where the exhaust amount of engine exhaust gas (heat amount of engine exhaust gas) gradually decreases as the load of the gas engine 3 decreases from this state.
In this case, the opening degree of the bypass valve 321 is set in advance by reducing the opening amount of the bypass valve 321 and reducing the exhaust flow amount of the engine exhaust gas to the bypass line 505 as the exhaust amount of the engine exhaust gas decreases. Unless the lower limit value (for example, “fully closed”) is reached, the supply flow rate (supply heat amount) of the engine exhaust gas to the engine exhaust gas introduction unit 22 is kept constant (step S101 in FIG. 4; NO).

Further, when the exhaust amount of the engine exhaust gas continues to decrease and the opening degree of the bypass valve 321 reaches a preset lower limit value (step S101 in FIG. 4; YES), the supply flow rate of the engine exhaust gas to the engine exhaust gas introduction unit 22 is increased. It begins to decline. Even in this case, the water W in the water tank 20 has a large heat capacity, and the temperature decrease of the water W accompanying the decrease in the supply flow rate of the engine exhaust gas, that is, the temperature decrease of the discharge NG proceeds slowly (FIG. 5C).

For this reason, the discharge flow rate of NG discharged from the SMV 2 does not rapidly decrease, and the product gas shipment pressure measured by the product gas pressure gauge 522 is maintained near the target pressure for the time being (FIG. 5). (A)). Accordingly, when the payout NG temperature measured by the payout NG thermometer 531 is higher than the preset lower limit value of the target temperature, and the burner 231 is in the stopped state, the operation state is continued as it is ( Step S102 in FIG. 4; NO → Step S106; YES).

When the exhaust gas emission amount further decreases and the discharge NG temperature starts to decrease beyond the allowable range with respect to the target temperature (step S102 in FIG. 4; YES), the burner 231 is already in the operating state. Check if it is. When the burner 231 is in a stopped state (step S103; NO), fuel is supplied from the fuel supply line 503 and air is supplied from the blower 24, and the burner 231 is ignited (step S104). Corresponding to the ignition of the burner 231, the load of the SMV 2 is in a state where the consumption flow rate of the burner 231 is added to the shipping flow rate required for the product gas (FIG. 5B).

As a result of the above-described operation, supply of the burner exhaust gas from the burner exhaust gas introduction unit 234 is started, so that a decrease in the supply flow rate of the engine exhaust gas is compensated for and the product gas shipping pressure is maintained at the target pressure (FIG. 5 (a)), the LNG supply amount adjusting unit 521 adjusts the supply flow rate of LNG.
When the engine exhaust gas supply flow rate further decreases or the LNG supply flow rate to the SMV 2 increases, the fuel supply flow rate to the burner 231 is increased to increase the introduction amount of the burner exhaust gas and vaporize NG. Ensuring the amount of heat necessary to make it happen.

When the payout NG temperature falls below the allowable range for the target temperature and the burner 231 is already in operation (step S103 in FIG. 4; YES), the capacity of the SMV2 exceeds the capability of the burner 231. The load is increasing. In this case, the payout flow rate underflow countermeasure that is different from the activation of the burner 231 is implemented (step S105).

Next, a sequence for stopping the operating burner 231 will be described. For example, consider a case where the exhaust amount of engine exhaust gas gradually increases from a steady state after the burner 231 is operated (the bypass valve 321 is closed and the burner 231 is operated).
In this case, as the exhaust amount of the engine exhaust gas increases, the amount of fuel gas supplied to the burner 231 is reduced (step S106 in FIG. 4; NO → step S107; NO).

When the amount of fuel gas supplied to the burner 231 reaches a preset lower limit value (minimum flow rate) (step S106 in FIG. 4; NO → step S107; YES), fuel from the fuel supply line 503 is obtained. Supply is stopped and the burner 231 is stopped (step S108). Corresponding to the stop of the burner 231, the load of SMV2 will be in the state corresponding only to the shipment flow rate required to maintain the target pressure of product gas.

As a result of the above-described operation, the introduction of the burner exhaust gas from the burner exhaust gas introduction unit 234 is stopped, and the discharge NG temperature is maintained at the target temperature only by the introduction of the engine exhaust gas from the engine exhaust gas introduction unit 22.
If the engine exhaust gas supply flow rate further increases or the LNG supply flow rate to the SMV 2 decreases, the bypass valve 321 is opened to start discharging the engine exhaust gas to the bypass line 505 (step S101; NO). .

The LNG storage facility according to the present embodiment has the following effects. Based on the measurement result of the pressure of the product gas containing vaporized NG, the heat for vaporizing the LNG is adjusted so that the amount of heat necessary to vaporize the LNG is supplied by adjusting the flow rate of the LNG supplied to the SMV 2. The introduction amount of the engine exhaust gas and the burner exhaust gas introduced into the water in which the exchange tube 21 is immersed is adjusted. As a result, stable shipment of the product gas can be realized while LNG is vaporized using the engine exhaust gas of the gas engine 3.

Here, in the LNG storage facility provided with the SMV 2 according to the above-described embodiment, it is not essential to use BOG as fuel for the gas engine 3. For example, as shown in FIG. 6, the gas engine 3 may be operated using part of the product gas extracted from the discharge line 502 to the fuel supply line 503. Further, both BOG and product gas may be used as fuel for the gas engine 3.

In addition, the confirmation that the amount of heat necessary for vaporizing the LNG supplied from the LNG supply line 501b side is supplied to the SMV 2 is as follows. However, the present invention is not limited to the case of using the method of measuring the temperature.
For example, a water temperature meter (water temperature measurement unit) (not shown) that measures the temperature of the water W in the water tank 20 is provided, and the temperature of the water W in the water tank 20 measured by the water temperature gauge approaches a preset target temperature. As described above, the exhaust gas introduction control unit 6 may employ a configuration in which the introduction amount of the engine exhaust gas or the burner exhaust gas is adjusted using the bypass valve 321 or the fuel gas flow rate adjustment valve 261 described above.

Further, in the flowchart of FIG. 4, the operation of switching the burner 231 between the operating state and the stopped state according to the increase or decrease of the exhaust amount of the engine exhaust gas from the gas engine 3 has been described. This does not deny the case where 231 is always in an operating state. In this case, for example, the supply flow rate ratio of the engine exhaust gas and the burner exhaust gas is fixed so that the discharge NG temperature or the temperature of the water W in the water tank 20 approaches the target temperature. A method for increasing or decreasing the amount can be exemplified.
As long as the exhaust gas of the gas engine 3 is used as a heat source sharing the amount of heat for vaporizing LNG, the amount of fuel consumed can be reduced as compared with the case where the burner 231 alone vaporizes LNG.

For convenience of illustration, FIGS. 1 and 6 show an example in which one SMV 2 is provided. However, a plurality of SMVs 2 are arranged in parallel between the storage tank 1 and the payout line 502. Or, of course, the SMV 2 and the open rack type LNG vaporizer may be arranged in parallel to vaporize the LNG delivered from the storage tank 1. Even in this case, LNG is distributed and supplied to each SMV 2 so that the shipping pressure of the product gas is maintained at the target pressure.

At this time, each SMV 2 adjusts the introduction amount of the engine exhaust gas and the burner exhaust gas by paying attention to an index different from the supply flow rate of LNG such as the discharge NG temperature and the temperature of the water W in the water tank 20. As a result, it is not necessary to grasp the operating state of other SMVs 2, and even if the operating number of SMVs 2 or the distribution ratio of LNG distributed to a plurality of SMVs 2 change, each SMV 2 has its own exhaust gas. The introduction amount adjustment is performed, and as a result, the shipping pressure of the product gas can be maintained at the target pressure.

1 and 6 show an example of an LNG storage facility in which only the gas engine 3 is provided. For example, in addition to the gas engine 3, a gas turbine is provided for the purpose of driving a generator 31, a compressor, and the like. In the LNG storage facility, a configuration in which gas turbine exhaust gas is merged with engine exhaust gas supplied to the SMV 2 may be adopted.
In addition, the SLNG 2 described with reference to FIGS. 1 to 3 and 6 may be provided in the LNG storage facility provided with only the gas turbine, and a technique of vaporizing LNG using the gas turbine exhaust gas and the burner exhaust gas may be employed.
In addition to these, it is not essential to provide the burner 231 and the burner exhaust gas introduction part 234 in the SMV 2, and LNG may be vaporized by the SMV 2 provided with only the engine exhaust gas introduction part 22.

W Water 1 Storage tank 2 SMV
20 Water tank 21 Heat exchange tube 22 Engine exhaust gas introduction part 231 Burner 234 Burner exhaust gas introduction part 24 Blower 261 Fuel gas flow control valve 3 Gas engine 31 Generator 322 Pressure gauge 4 BOG compressor 41

Gas holder

501a, 501b
LNG supply line 502 Discharge line 503 Fuel supply line 504 Exhaust gas supply line 505 Bypass line 521 LNG supply amount adjustment unit 522 Product gas pressure gauge 531 Discharge NG thermometer 532 Load adjustment unit 6 Exhaust gas introduction control unit

Claims

In the liquefied natural gas storage facility that vaporizes the liquefied natural gas stored in the storage tank and then delivers it to the outside,
A gas engine that drives the generator;
A submerged liquefied natural gas vaporizer that vaporizes liquefied natural gas supplied from the storage tank, and
The submerged liquefied natural gas vaporizer is
A water tank in which water is stored;
A liquefied natural gas supply line that is arranged so as to be immersed in water in the water tank and that is supplied with liquefied natural gas from the storage tank, and for discharging the vaporized natural gas obtained by vaporizing the liquefied natural gas A vaporizer for heating and vaporizing the liquefied natural gas flowing through the heat exchange tube by heat exchange with the water in the water tank.
Introduction of engine exhaust gas for introducing engine exhaust gas received through an exhaust gas supply line to which engine exhaust gas is supplied from the gas engine into the water in the water tank and supplying combustion exhaust heat of the gas engine to the water And
A burner that mixes fuel and air to burn the fuel, a fuel supply unit that supplies fuel to the burner, a blower unit that supplies air, and a fuel burned by the burner A burner exhaust gas for introducing the burner exhaust gas into the water in the water tank and supplying the heat of combustion of the fuel to the water, and
Furthermore, an engine exhaust gas flow rate adjusting unit for adjusting a supply flow rate of engine exhaust gas from the gas engine to the engine exhaust gas introducing unit,
A burner load adjuster for adjusting the flow rate of fuel supplied to the burner;
A pressure measuring unit that is discharged from the discharge line and measures the pressure of the product gas including the vaporized natural gas;
A liquid feed flow rate adjusting unit that adjusts the flow rate of the liquefied natural gas supplied to the liquefied natural gas vaporizer so that the pressure of the product gas measured by the pressure measuring unit approaches a preset target pressure; ,
The engine exhaust gas flow rate adjusting unit and the burner load adjusting unit are arranged so that the amount of heat necessary for vaporizing the liquefied natural gas at the flow rate adjusted by the liquid supply flow rate adjusting unit is supplied to the liquefied natural gas vaporizer. A liquefied natural gas storage facility, comprising: an exhaust gas introduction control unit that adjusts an introduction amount of engine exhaust gas and burner exhaust gas into water in the water tank.
A natural gas temperature measuring unit for measuring the temperature of vaporized natural gas discharged from the liquefied natural gas vaporizer to a discharge line;
The exhaust gas introduction control unit is configured to introduce the engine exhaust gas and the burner exhaust gas into the water in the water tank so that the temperature of the vaporized natural gas measured by the natural gas temperature measurement unit approaches a preset target temperature. The liquefied natural gas storage facility according to claim 1, wherein a necessary amount of heat is supplied by the liquefied natural gas vaporizer by adjusting the amount of gas.
A water temperature measuring unit for measuring the temperature of water in the aquarium,
The exhaust gas introduction control unit adjusts the introduction amount of the engine exhaust gas and the burner exhaust gas into the water in the water tank so that the temperature of the water measured by the water temperature measurement unit approaches a preset target temperature. The liquefied natural gas storage facility according to claim 1, wherein a necessary amount of heat is supplied by the liquefied natural gas vaporizer.
Supplying fuel from the fuel supply unit to the burner, stopping, and including a fuel cutting unit for switching the burner between a stopped state and an operating state,
The exhaust gas introduction control unit adjusts the supply flow rate of the engine exhaust gas to the engine exhaust gas introduction unit using the engine exhaust gas flow rate adjustment unit so that a necessary amount of heat is supplied by the natural gas vaporizer, and When the engine exhaust gas flow rate adjustment unit exceeds the engine exhaust gas adjustment capability and the liquefied natural gas vaporizer needs heat, and the burner is in a stopped state, the fuel cut-off unit is used. 2. The liquefied natural gas storage facility according to claim 1, wherein fuel is supplied from a fuel supply unit to place the burner in an operating state.
The exhaust gas introduction control unit is configured to supply fuel to the burner under a condition in which an introduction amount of engine exhaust gas and burner exhaust gas corresponding to the amount of heat necessary for the liquefied natural gas vaporizer is introduced into the water in the water tank. When the supply flow rate becomes a preset minimum flow rate, the fuel supply unit stops the fuel supply from the fuel supply unit and switches the burner to a stop state. 4. The liquefied natural gas storage facility according to 4.
A bypass line for bypassing the engine exhaust gas introduction part and exhausting the engine exhaust gas to the outside;
The exhaust gas introduction control unit is configured to provide an engine exhaust gas to the engine exhaust gas introduction unit under a condition that an introduction amount of engine exhaust gas corresponding to a heat amount necessary for the liquefied natural gas vaporizer is introduced into water in the water tank. When the engine exhaust gas larger than the supply flow rate is exhausted from the gas engine and the burner is in a stopped state, excess engine exhaust gas is discharged to the outside through the bypass line. The liquefied natural gas storage facility according to claim 4.
The liquefied natural gas storage facility according to claim 1, wherein boil-off gas generated in the storage tank is used as fuel gas of the gas engine.
The liquefied natural gas storage facility according to claim 1, wherein at least one of boil-off gas generated in the storage tank or liquefied petroleum gas is added to the product gas.