KR102560206B1 - Liquefied gas vaporization device and floating body facility equipped with the same - Google Patents

Abstract

Provided is a liquefied gas vaporization device having no fear of freezing in a vaporizer and excellent energy saving effect. It is provided with a steam turbine 32 through which the steam generated by the exhaust gas economizer 14 from which the exhaust gas of the diesel engine 5 is guided is guided, a condenser 36 which condenses the steam discharged from the steam turbine 32, a vaporizer 25 which heats and vaporizes LNG, and a glycol circulation path 38 connected to the vaporizer 25 and through which glycol circulates. The condenser 36 and the glycol circulation path 38 are thermally connected so as to supply heat to the glycol circulating from the condenser 36 through the glycol circulation path 38.

Description

Liquefied gas vaporization device and floating body facility equipped with the same

The present invention relates to a liquefied gas vaporization device that vaporizes a liquefied gas and a floating body facility equipped with the same.

In an LNG ship transporting LNG gas, it is known to effectively use the steam generated in the boiler by burning the boil-off gas inevitably generated in the LNG tank due to intrusion heat or the like in a boiler (see, for example, Patent Document 1).

BACKGROUND OF THE INVENTION Floating body facilities such as a Floating Storage and Regasification Unit (FSRU) are provided with a liquefied gas vaporizer that regasifies LNG (liquefied gas) stored in an LNG tank and supplies it to the outside. It is known to use seawater as a heat source when liquefied gas is vaporized in a liquefied gas vaporizer.

Japanese Patent No. 4119725

If low-temperature seawater is flowed through a vaporizer that vaporizes liquefied gas in the liquefied gas vaporizer of the FSRU, there is a fear that the liquefied gas will freeze the seawater as it cools.

It is also conceivable to use the vapor generated by burning the boil-off gas generated in the LNG tank as in Patent Literature 1 as a heat source for a vaporizer that vaporizes liquefied gas. However, there is a demand for a vaporization method in which an additional energy saving effect can be expected.

The present invention has been made in view of such a situation, and an object of the present invention is to provide a liquefied gas vaporization device having no fear of freezing in a vaporizer and having an excellent energy saving effect, and a floating body facility equipped with the same.

A liquefied gas vaporizer according to one aspect of the present invention includes a steam turbine to which steam generated by an exhaust gas economizer is guided, to which exhaust gas from a power generation engine is guided, a condenser to condense steam discharged from the steam turbine, a vaporizer to heat and vaporize liquefied gas, an antifreeze circulation path connected to the vaporizer and through which antifreeze is circulated, and antifreeze heating means to supply heat from the condenser to the antifreeze circulating in the antifreeze circulation path.

The antifreeze circulating in the antifreeze circulation path is heated by a condenser connected to a steam turbine that operates by recovering exhaust heat from an engine for power generation. Then, the liquefied gas is vaporized by a vaporizer connected to the antifreeze circulation path. Thereby, the exhaust heat of the condenser can be effectively used for vaporization of the liquefied gas, and energy saving can be realized.

Since antifreeze is used as the fluid flowing in the circulation path connected to the vaporizer, there is no fear of freezing in the vaporizer compared to the case where seawater or fresh water is used.

As an antifreeze, glycols, such as ethylene glycol, are used, for example.

Further, in the liquefied gas vaporization device according to one aspect of the present invention, the antifreeze heating means includes the condenser for exchanging heat with the antifreeze circulating in the antifreeze circulation path.

It was set as heat exchange between the antifreeze and the fluid (steam or condensate) in the condenser. In this way, since the antifreeze and the fluid in the condenser can be heat exchanged without intervening other media, heat exchange loss can be suppressed as much as possible.

Further, in the liquefied gas vaporization device according to one aspect of the present invention, the antifreeze heating unit includes a water circulation path through which water circulates and heat is supplied from the condenser to the antifreeze circulation path.

It was decided to form a water circulation path that supplies heat from the condenser to the antifreeze circulation path. Thus, the length of the antifreeze circulation path can be reduced. In general, since antifreeze has a higher viscosity than water, the pump power of the antifreeze circulation path can be reduced by employing a water circulation path.

As water used for the water circulation route, seawater or fresh water is used, for example.

In addition, in the liquefied gas vaporization device according to one aspect of the present invention, a seawater heat exchanger installed in the antifreeze circulation path and exchanging heat between the antifreeze and seawater after passing through the vaporizer is provided.

By installing the seawater heat exchanger in the antifreeze circulation path, the antifreeze whose temperature has decreased by passing through the vaporizer can be heated by seawater. Thus, it is possible to configure an open loop in which liquefied gas is vaporized using seawater and the vaporized seawater is discharged into the sea.

Since the antifreeze is heated by the condenser, the amount of heating by seawater can be reduced. In this way, even if the seawater cooled in the seawater heat exchanger is discharged into the ocean, it is possible to avoid having a large impact on the environment.

Further, in the liquefied gas vaporization device according to one aspect of the present invention, the antifreeze heating means includes a heated water supply path for sending water heated by heat exchange in the condenser to the seawater heat exchanger.

It was decided to form a heated water supply path for supplying heat from the condenser to the seawater heat exchanger. Thus, the length of the antifreeze circulation path can be reduced. In general, since antifreeze has a higher viscosity than water, the pump power of the antifreeze circulation path can be reduced by employing a water circulation path.

In addition, since heated water can be supplied to the seawater heat exchanger, the amount of seawater used in the seawater heat exchanger can be reduced, and thus the environmental load can be reduced.

As water used for the water circulation route, seawater or fresh water is used, for example.

Further, in the liquefied gas vaporizer according to one aspect of the present invention, a boiler for generating steam and a steam heat exchanger for exchanging heat between the steam generated in the boiler and the antifreeze circulating in the antifreeze circulation path are provided.

In the steam heat exchanger, the antifreeze can be heated by the steam produced by the boiler. In the case where a seawater heat exchanger is not used, a so-called closed loop or combined loop can be configured.

In addition, in a liquefied gas vaporizer associated with one embodiment of the present invention, the controller for controlling the steam supply system produced in the boiler and the steam supply system for the steam turbine, the vapor amount derived from the steam turbine and the steam heat exchanger, and the controller, the controller, the controller, the controller, the controller, the controller, the controller. When the amount of liquefied gas vaporized in the vaporization exceeds the predetermined value, the vapor amount induced with the steam turbine is reduced, and the vapor amount led by the steam heat exchanger is increased.

Since there is a predetermined limit on the capacity of the boiler, when the amount of liquefied gas vaporized in the vaporizer increases, it may become impossible to supply steam to both the steam heat exchanger and the steam turbine. Therefore, when the amount of liquefied gas vaporized in the vaporizer exceeds a predetermined value, the amount of steam guided to the steam turbine is reduced and the amount of steam guided to the steam heat exchanger is increased. This makes it possible to secure the amount of heat required to vaporize the liquefied gas.

For example, in order to make the size of the boiler as small as possible, it is particularly effective when the capacity of the boiler is limited to the amount of steam required to vaporize the maximum amount of liquefied gas.

Further, in the liquefied gas vaporizer according to one aspect of the present invention, a steam turbine generator driven by the steam turbine, a circulation pump installed in the antifreeze circulation path, and a liquefied gas pump for sending liquefied gas to the vaporizer are provided, and the circulation pump and/or the liquefied gas pump are driven by electric power generated by the steam turbine generator.

Since the electric power generated by the steam turbine generator can be used for a circulation pump and/or a liquefied gas pump for circulating antifreeze, the load on the engine for power generation can be reduced.

In addition, the invention of this aspect can be combined with the invention of each aspect described above.

Further, a floating body facility according to one aspect of the present invention includes the liquefied gas vaporizer according to any one of the above and a liquefied gas tank for storing liquefied gas, the engine for power generation is operated by boil-off gas generated in the liquefied gas tank, and the vaporizer vaporizes the liquefied gas derived from the liquefied gas tank.

By providing the above liquefied gas vaporizing device, it is possible to provide a floating body facility with excellent energy saving effect. As a floating body facility, a FSRU (Floating Storage and Regasification Unit) is mentioned, for example.

In addition, the invention of this aspect can be combined with the invention of each aspect described above.

Since antifreeze is used, freezing in the vaporizer can be avoided. In addition, since the exhaust heat of the condenser of the steam turbine is used, it can contribute to energy saving.

1 is an LNG vaporization facility applied to a FSRU (combined loop) according to a first embodiment of the present invention, and is a schematic configuration diagram when used as an open loop.
FIG. 2 is a schematic configuration diagram of the LNG vaporization facility in FIG. 1 when used as a closed loop.
3 is a graph showing the amount of heat versus the amount of LNG gas delivered.
4 is a graph showing an enlarged upper right portion of FIG. 3 .
Fig. 5 is a schematic configuration diagram showing an LNG vaporization facility applied to an FSRU according to a second embodiment of the present invention.
Fig. 6 is a schematic configuration diagram showing a modified example of Fig. 5;

EMBODIMENT OF THE INVENTION Below, embodiment concerning this invention is described with reference to drawings.

[First Embodiment]

Hereinafter, the first embodiment of the present invention will be described.

1 shows a schematic configuration of an LNG vaporizer (liquefied gas vaporizer) 1A that vaporizes LNG (liquefied gas), which is liquefied natural gas, and supplies it to the outside. The LNG vaporization device 1A is installed in a Floating Storage and Regasification Unit (FSRU) which is a floating body facility.

The FSRU is equipped with an LNG tank 3 and a diesel engine (engine for power generation) 5 in addition to the LNG vaporizer 1A.

In the LNG tank 3, LNG is stored. Above the LNG tank 3, BOG (boil-off gas) unavoidably generated due to intrusion heat or the like remains. BOG is guided to the diesel engine 5 through the BOG supply pipe 7. A BOG compressor 9 and a BOG cooling heat exchanger 10 are installed in the BOG supply pipe 7 . After the BOG is boosted up to the pressure required by the diesel engine 5 by the BOG compressor 9, the BOG is cooled by the BOG cooling heat exchanger 10. The BOG cooled by the BOG cooling heat exchanger (10) is led to the diesel engine (5).

The diesel engine 5 drives an unillustrated generator. A generator driven by the diesel engine 5 generates electric power required in the FSRU.

A supercharger 12 is installed in the diesel engine 5 . The supercharger 12 is equipped with an exhaust turbine and an air compressor, not shown. The exhaust turbine and air compressor are connected by a common shaft so that they rotate together.

Exhaust gas that has passed through the exhaust turbine of the supercharger 12 is guided to the exhaust gas economizer 14 . An exhaust gas bypass pipe 15 is provided so as to bypass the exhaust gas economizer 14 . When using the exhaust gas economizer 14, the bypass valve 15a is closed. Also, in this embodiment, a valve shown in black means closed, and a valve shown in white means open. Therefore, when using the exhaust gas economizer 14, the exhaust gas economizer valve 14a provided upstream of the exhaust gas economizer 14 is opened.

The air compressed by the air compressor of the supercharger 12 is led to the diesel engine 5 after being cooled in the air cooler 16 .

The LNG in the LNG tank 3 is guided to the gas-liquid separator 20 installed outside the LNG tank 3 by the LNG pump 18 installed in the LNG tank 3. The LNG separated from the gas phase in the gas-liquid separator 20 is guided to the vaporizer 25 via the LNG pipe 23 by the liquid feed pump (liquefied gas pump) 22 . The LNG pump 18 and the liquid feed pump 22 are electric pumps. LNG vaporized in the vaporizer 25 is supplied to the outside through the transfer gas pipe 26 . Starting and stopping the LNG pump 18 and the liquid feed pump 22 and controlling the number of revolutions are performed by a control unit (not shown).

In addition to the vaporizer 25, the LNG vaporizer 1A includes a Regas boiler 30, a steam turbine 32, a steam turbine generator 34, a condenser 36, and a glycol circulation path (antifreeze circulation path) 38 that thermally connects the condenser 36 and the vaporizer 25.

The BOG supply piping 40 for boilers branched from the BOG supply piping 7 is connected to the regas boiler (boiler) 30. The regas boiler 30 operates using BOG guided by the BOG supply pipe 40 for boilers as a fuel. In addition, the regas boiler 30 may be operated by fuel oil. In addition, in FIG. 1, although the BOG supply pipe 40 for a boiler is shown by the broken line, this means that it is not using it.

The water drum 30a of the regas boiler 30 is connected to the evaporator 44 in the exhaust gas economizer 14 via a drum water pump 42 . The water heated by the evaporator 44 is guided to the steam drum 30b of the regas boiler 30. Water is supplied to the steam drum 30b from the water supply tank 46 via the water supply pipe 47 by the water supply pump 48.

Steam is supplied from the steam drum 30b of the regas boiler 30 to the steam demand part 50 in the FSRU (inside the ship) through the inboard steam supply valve 51.

Between the steam drum 30b of the regas boiler 30 and the steam turbine 32, the steam pipe 52 for steam turbines is provided. The superheater 53 is installed in the middle position of the steam piping 52 for steam turbines. The superheater 53 is installed in the exhaust gas economizer 14 . In the steam piping 52 for steam turbines, between the superheater 53 and the steam turbine 32, a steam stop valve 54 and a steam regulating valve 55 are provided. The steam stop valve 54 and the steam regulating valve 55 are controlled by a control unit not shown.

In the steam piping 52 for steam turbines, a branch point P is formed on the upstream side of the superheater 53 . Between the branch point P and the condenser 36, a steam dump pipe 57 is provided that exhausts the steam in the steam drum 30b to the condenser 36 by bypassing the steam turbine 32. A steam dump valve 58 is installed in the steam dump pipe 57 . The steam dump valve 58 is controlled by a control unit (not shown) and is closed during normal operation.

A steam supply pipe 62 is provided between the steam drum 30b of the regas boiler 30 and the steam heat exchanger 60 provided in the glycol circulation path 38. A steam supply valve 63 is installed in the steam supply pipe 62 . The steam supply valve 63 is controlled by a control unit not shown. The steam after heating the glycol in the steam heat exchanger 60 turns into drain water and is guided to the water supply tank 46 through the drain water pipe 65. In addition, as glycol, ethylene glycol is used, for example. In addition, in the state shown in FIG. 1, since steam is not guided from the steam supply pipe 62 to the steam heat exchanger 60 as indicated by the broken line, the drain water pipe 65 is not used.

The steam turbine 32 rotates the rotating shaft 33 while being rotated by steam. The rotary shaft 33 is connected to the steam turbine generator 34 and drives the steam turbine generator 34 . Electric power generated by the steam turbine generator 34 is used as necessary electric power in the ship, and is used, for example, for the liquid feed pump 22 for sending LNG and the circulation pump 67 for circulating glycol.

Steam that has completed work in the steam turbine 32 is guided to the condenser 36 . The condensate condensed in the condenser 36 is guided to the water supply tank 46 via the condensate pump 69 . Inside the condenser 36, a glycol circulation path 38 is connected. Thereby, in the condenser 36, the steam induced from the steam turbine 32 and the glycol circulating in the glycol circulation path 38 undergo heat exchange.

A seawater heat exchanger 72 is installed in the glycol circulation path 38. In the seawater heat exchanger 72, seawater guided through the seawater intake pipe 71 by the seawater pump 70 and glycol exchange heat. The seawater that has undergone heat exchange in the seawater heat exchanger 72 is discharged to the sea through the drainage pipe 73. The seawater pump 70 is controlled by a control unit not shown.

The glycol circulation path 38 is provided with a circulation pump 67 on the upstream side of the seawater heat exchanger 72 . The glycol circulates through the seawater heat exchanger 72, the condenser 36, the steam heat exchanger 60, and the vaporizer 25 in this order by the circulation pump. The circulation pump 67 is an electric pump and is controlled by a control unit not shown.

The control unit is composed of, for example, a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), a computer-readable storage medium, and the like. A series of processes for realizing various functions is, as an example, stored in a storage medium or the like in the form of a program, and the CPU reads the program into RAM or the like to process and calculate information, thereby realizing the various functions. In addition, the program may be installed in advance in a ROM or other storage medium, provided in a state stored in a computer-readable storage medium, distributed through wired or wireless communication means, and the like. Computer-readable storage media include magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, semiconductor memories, and the like.

<open loop>

Next, the operation of the LNG vaporizer 1A having the above configuration will be described. First, an open loop using the seawater heat exchanger 72 without using the steam heat exchanger 60 will be described. In the case of an open loop, seawater cooled by heating glycol in the seawater heat exchanger 72 is discharged to the sea. For this reason, an open roof is used in sea areas where the water temperature is high or in the summer.

In the open loop, the regas boiler 30 does not operate. Therefore, there is no case where BOG is induced through the BOG supply pipe 40 for the boiler. The steam drum 30b of the regas boiler 30 is used as a gas-liquid separator. The control unit activates the drum water pump 42 to guide the water in the water drum 30a to the evaporator 44 to exchange heat with the exhaust gas flowing through the exhaust gas economizer 14 . The water guided to the evaporator 44 is heated and then guided to the steam drum 30b to undergo gas-liquid separation. The steam separated from the steam drum 30b is guided to the steam demand part 50 and the steam turbine 32 . The steam guided to the steam turbine 32 is superheated by the superheater 53 of the exhaust gas economizer 14 . Exhaust gas generated in the diesel engine 5 is guided to the exhaust gas economizer 14 .

The control unit closes the steam supply valve 63 so that steam does not flow through the steam heat exchanger 60 . In addition, the control unit controls the operation of the liquid feed pump 22, the circulation pump 67, the seawater pump 70, and the like.

The LNG guided from the LNG tank 3 is supplied to the vaporizer 25 by the liquid feed pump 22 via the LNG pipe 23. In the vaporizer 25, it is heated and vaporized by the glycol flowing through the glycol circulation path 38. The vaporized LNG is guided to an external consumer through the transfer gas pipe 26 .

Glycol cooled by vaporizing LNG in the vaporizer 25 is heated by seawater in the seawater heat exchanger 72 . Glycol heated by seawater is guided to the condenser 36 through the glycol circulation path 38. In the condenser 36, glycol is heated by taking condensation heat from the steam induced from the steam turbine 32. Glycol thus heated in the condenser 36 is guided to the steam heat exchanger 60 through the glycol circulation path 38. Compared to the case where LNG is vaporized using only seawater as a heat source, the amount of heat to be obtained from seawater can be reduced by using exhaust steam from a steam turbine as a heat source as well. In short, since the required amount of seawater is reduced, power consumption for driving the seawater pump can also be reduced.

In the steam heat exchanger 60, since steam is not guided from the regas boiler 30, glycol is guided to the vaporizer 25 without being heated in the steam heat exchanger 60.

＜Combined (closed) loop＞

Next, with reference to FIG. 2, a combined loop or closed loop using the steam heat exchanger 60 will be described. In the combined loop and the closed loop, both use the steam heat exchanger 60 in common. However, in the closed loop, the seawater heat exchanger 72 is not used, and in the combined loop, the seawater heat exchanger 72 is partially used.

BOG from the LNG tank 3 is guided to the regas boiler 30 through the BOG supply pipe 40 for the boiler. In the regas boiler 30, by forming a flame in a burner (not shown) using BOG as fuel, the feed water supplied through the feed water pipe 47 is heated to generate steam. The generated steam is guided to the steam demand part 50 from the steam drum 30b and to the steam turbine 32 . The steam guided to the steam turbine 32 is superheated by the superheater 53 of the exhaust gas economizer 14 . Exhaust gas generated in the diesel engine 5 is guided to the exhaust gas economizer 14 .

The control unit opens the steam supply valve 63 and stops the seawater pump 70. As a result, the glycol flowing through the glycol circulation path 38 is heated by the steam heat exchanger 60. In addition, glycol is heated also in the condenser 36 similarly to the case of an open loop.

In this way, since the seawater heat exchanger 72 is not used in the closed loop, the cooled seawater is not discharged to the sea. Therefore, environmental load can be reduced.

In addition, if necessary, seawater may be supplied to the seawater heat exchanger 72 in a required amount as a combined loop to auxiliary heat the glycol.

<Examination of Efficiency>

As shown in FIG. 2, part of the steam generated by the regas boiler 30 is guided to the steam turbine 32 to obtain power from the steam turbine generator 34, and the exhaust heat of the steam turbine 32 is recovered by the condenser 36 in the glycol circulation path 38. As a result, the amount of generated steam of the regas boiler 30 used to vaporize LNG can be reduced compared to the case where the heat of vaporization of LNG is procured in the regas boiler 30 without performing heat recovery in the condenser 36 (hereinafter referred to as “total steam heating”).

Heating by steam heating has higher heat conversion efficiency than heating using exhaust heat after passing through the steam turbine 32 . However, in all steam heating, the necessary power must be supplied only by the diesel engine, which is a separate system, but in the present embodiment, since the power generated by exhaust heat recovery from the diesel engine is added, the fuel consumed by the diesel engine can be reduced.

In the present embodiment, since glycol heating is provided by exhaust heat recovery of the steam heat exchanger 60 using steam derived from the regas boiler 30 and the condenser 36 using steam after passing through the steam turbine 32, the amount of evaporation in the regas boiler 30 is higher than that of steam heating. However, when the power required for LNG vaporization (the power of the circulation pump 67 or the liquid feed pump 22) and the LNG vaporization heat source are regarded as one plant, in the present embodiment, since the exhaust heat of the condenser 36 can be used for heating LNG, a thermal efficiency approximately expressed as “(boiler efficiency) × (turbine internal efficiency)” can be obtained. Thereby, reduction of required electric power in the diesel engine 5, ie reduction of fuel consumption becomes possible.

<Steam amount distribution control>

Next, steam amount distribution control performed by the control unit will be described. Steam amount distribution control means control of the amount of steam distributed to the steam heat exchanger 60 and the steam turbine 32 . Specifically, it is implemented by controlling the opening of the steam supply valve 63 and/or the steam regulating valve 55.

Figure 3 shows the way of thinking of vapor distribution control. In the figure, the horizontal axis represents the amount of LNG delivered to the outside through the transfer gas pipe 26 of the LNG vaporized in the vaporizer 25, and the vertical axis represents the amount of heat.

The solid line represents the amount of heat required in the vaporizer 25 corresponding to the amount of LNG delivered on the horizontal axis. The broken line indicates the amount of heat recovered in the condenser 36, that is, the amount of heat recovered from the steam exhausted by the steam turbine 32 driven by the steam distributed by the control unit to the glycol circulation path 38 in the condenser 36. The dashed-dotted line represents the amount of heat input to the steam heat exchanger 60, that is, the amount of heat imparted to glycol in the steam heat exchanger 60 from the steam distributed by the control unit. The two-dot chain line represents the amount of heat of the steam generated in the regas boiler 30.

Therefore, the sum of the amount of heat recovered from the condenser 36 indicated by the broken line and the amount of heat supplied to the steam heat exchanger 60 indicated by the dashed line becomes the amount of heat required for LNG delivery indicated by the solid line. The amount of steam heat generated in the regas boiler 30 indicated by the two-dot chain line is slightly larger than the required heat amount indicated by the LNG delivery indicated by the solid line. This is because the amount of steam heat supplied to the steam demand section 50 and the like are added.

The amount of recovered heat in the condenser 36, indicated by the broken line, is constant up to the threshold value F1, which is the predetermined LNG output amount. This recovered heat amount is set to a heat amount corresponding to the amount of steam that can obtain the maximum output from the steam turbine generator 34, for example.

Up to the critical value F1 of the amount of LNG discharged, as indicated by the solid line, the amount of required heat monotonically increases in proportion to the amount of discharged LNG. Correspondingly, the control unit increases the amount of steam generated in the regas boiler 30 (see two-dot chain line) and increases the steam flow rate distributed to the steam heat exchanger 60 (see one-dotted line).

When the LNG delivery amount threshold value F1 is exceeded, the control unit decreases the amount of steam supplied to the steam turbine 32 as the LNG delivery amount increases (see the broken line). Corresponding to the decrease in the amount of steam, the amount of steam supplied to the steam heat exchanger 60 is increased (see dashed line). Preferably, a decrease in the amount of steam for the steam turbine 32 and an increase in the amount of steam for the steam heat exchanger 60 are matched. In this way, it is possible to secure the amount of heat required for LNG delivery indicated by the solid line.

The reason for controlling as described above is as follows.

FIG. 4 is an enlarged view of the upper right corner of FIG. 3 . As shown in the same figure, the capacity of the regas boiler 30 is set to a heat quantity corresponding to the maximum value Fmax of the LNG delivery amount (see line L1) in order to make it a necessary and sufficient size. That is, the capacity of the regas boiler 30 is set so that the amount of heat obtained by the vaporizer 25 through the glycol circulation path 38 when all the steam generated in the regas boiler 30 at the maximum load is supplied to the steam heat exchanger 60 corresponds to the heat of vaporization of LNG at which the LNG output amount is the maximum value Fmax.

Therefore, in a state where all steam is not supplied to the steam heat exchanger 60 and part of the steam is distributed to the steam turbine 32, as indicated by the line L2, the limit value F2 becomes the upper limit of the LNG output. Then, as shown in FIG. 3, when the threshold value F1 is exceeded, the amount of steam distributed to the steam turbine 32 is reduced.

<Operation and effect of the present embodiment>

According to this embodiment, the following effects are exhibited.

The glycol circulating in the glycol circulation path 38 is heated by a condenser 36 connected to a steam turbine 32 that operates by recovering exhaust heat from the diesel engine 5 in the exhaust gas economizer 14. And LNG is vaporized by the vaporizer 25 connected to the glycol circulation path 38. Thereby, the exhaust heat of the condenser 36 can be effectively used for vaporizing LNG, and energy saving can be realized.

Since glycol, which is an antifreeze, is used as the fluid flowing through the glycol circulation path 38 connected to the vaporizer 25, there is no fear of freezing in the vaporizer 25 compared to the case where seawater or fresh water is used.

Glycol was guided to the condenser 36, and the glycol and the steam in the condenser 36 were heat-exchanged. In this way, since heat exchange between glycol and steam is possible without intervening through another medium, heat exchange loss can be suppressed as much as possible.

By installing the seawater heat exchanger 72 in the glycol circulation path 38, the glycol whose temperature has decreased through the vaporizer 25 can be heated by seawater. Thereby, it is possible to configure an open loop (refer to FIG. 1) in which LNG is vaporized using seawater and the vaporized seawater is discharged into the ocean.

Since glycol is heated by the condenser 36, the heating amount by seawater can be reduced. In this way, even if the seawater cooled by the seawater heat exchanger 72 is discharged to the sea, it is possible to avoid having a large impact on the environment.

With the steam heat exchanger 60, glycol can be heated by steam generated in the regas boiler 30. In the case where the seawater heat exchanger 72 is not used, a so-called closed loop or combined loop can be configured (see Fig. 2).

Since the capacity of the regas boiler 30 has a predetermined limit, when the amount of LNG exported after being vaporized in the vaporizer 25 increases, steam may not be supplied from the regas boiler 30 to both the steam heat exchanger 60 and the steam turbine 32. Therefore, when the amount of LNG vaporized in the vaporizer 25 exceeds a predetermined value, the amount of steam guided to the steam turbine 32 is reduced and the amount of steam guided to the steam heat exchanger 60 is increased. In this way, it is possible to secure the amount of heat required to vaporize the LNG.

As in the present embodiment, since the size of the regas boiler 30 is made as small as possible, it is particularly effective when the boiler capacity is limited to the amount of steam required to vaporize the maximum amount of LNG output.

Since the electric power generated by the steam turbine generator 34 can be used for the circulation pump 67 and/or the liquid feed pump 22 for circulating glycol, the load on the diesel engine 5 can be reduced.

[Second Embodiment]

Next, a second embodiment of the present invention will be described using FIG. 5 .

This embodiment differs from the first embodiment in the method of transferring heat between the condenser 36 and the glycol circulation path 38, and the other matters are the same. Therefore, in the following description, the difference with respect to 1st Embodiment is demonstrated, and the others are given the same code|symbol, and the description is abbreviate|omitted.

As shown in FIG. 5 , the LNG vaporizer 1B of the present embodiment is provided with a water circulation path 80 between the condenser 36 and the glycol circulation path 38 . As water used for the water circulation path 80, seawater or fresh water can be used, for example. Through the water circulation path 80, the exhaust heat of the condenser 36 is applied to the glycol of the glycol circulation path 38.

The water flowing through the water circulation path 80 exchanges heat with steam in the condenser 36 . Between the water circulation path 80 and the glycol circulation path 38, a water heat exchanger 82 is provided. In the water heat exchanger 82, the glycol of the glycol circulation path 38 is heated by the water of the water circulation path 80.

In this way, by forming the water circulation path 80 between the condenser 36 and the glycol circulation path 38, the length of the glycol circulation path 38 can be reduced. For example, in the configuration in which the glycol circulation path 38 is connected to the condenser 36 as in the first embodiment, when the distance between the condenser 36 and the vaporizer 25 is far apart, the distance of the glycol circulation path 38 has no choice but to be taken long. In contrast, in this embodiment, since the water circulation path 80 is interposed between the condenser 36 and the glycol circulation path 38, the glycol circulation path 38 can be shortened.

In general, since glycol has a higher viscosity than water, the pump power of the circulation pump 67 installed in the glycol circulation path 38 can be reduced by adopting the water circulation path 80.

Further, this embodiment can be modified as shown in FIG. 6 . That is, instead of the water circulation path 80 of FIG. 5, a heated water supply path 85 is formed between the condenser 36 and the glycol circulation path 38. The heated water supply path 85 supplies seawater to the condenser 36, recovers exhaust heat from the condenser 36 with seawater, and then supplies the seawater to the seawater heat exchanger 72. The seawater intake piping 71 joins the seawater upstream. In this way, exhaust heat from the condenser 36 may be supplied to the glycol circulation path 38.

1A, 1B; LNG vaporizer (liquefied gas vaporizer)
3 ; LNG tank (liquefied gas tank)
5 ; Diesel engine (engine for power generation)
7; BOG supply piping
9; BOG Compressor
10; BOG cooling heat exchanger
12; supercharger
14; exhaust gas economizer
14a; exhaust gas economizer valve
15; Exhaust gas bypass piping
15a; bypass valve
16; air cooler
18; LNG pump
20; gas-liquid separator
22; Liquid transfer pump (liquefied gas pump)
23; LNG piping
25; carburetor
26; transport gas piping
30; Rigas boiler (boiler)
30a; water drum
30b; steam drum
32; steam turbine
33; axis of rotation
34; steam turbine generator
36; revenge
38; Glycol Circulation Path (Antifreeze Circulation Path)
40; BOG supply piping for boiler
42; drum water pump
44; evaporator
46; feed tank
47; water supply plumbing
48; feed pump
50; steam demand side
51; On board steam supply valve
52; Steam piping for steam turbines
53; superheater
54; steam stop valve
55; steam relief valve
57; steam dump piping
58; steam dump valve
60; steam heat exchanger
62; steam supply piping
63; steam supply valve
65; Drain water piping
67; circulation pump
69; revenge pump
70; sea water pump
71; Sea water intake piping
72; sea water heat exchanger
73; drainage plumbing
80; water cycle path
82; water heat exchanger
85; Heated water supply route

Claims (9)

a steam turbine to which steam generated by an exhaust gas economizer, to which exhaust gas of an engine for power generation is induced, is induced;
a condenser for condensing the steam by guiding steam that has finished work in the steam turbine;
A vaporizer for heating and vaporizing liquefied gas;
An antifreeze circulation path connected to the carburetor and circulating antifreeze;
an antifreeze heating means for supplying heat from the condenser to the antifreeze circulating in the antifreeze circulation path;
A boiler that produces steam;
A steam heat exchanger for heat exchange between the steam generated in the boiler and the antifreeze circulating in the antifreeze circulation path;
A steam supply system for a turbine in which steam generated in the boiler is guided to the steam turbine;
A control unit for controlling the amount of steam induced to the steam turbine through the steam supply system for the turbine and the amount of steam induced to the steam heat exchanger
is provided,
the antifreeze heating means includes the condenser for heat exchange with the antifreeze circulating in the antifreeze circulation path, and the antifreeze circulation path is connected in the condenser;
The control unit reduces the amount of steam guided to the steam turbine and increases the amount of steam guided to the steam heat exchanger when the amount of liquefied gas vaporized in the vaporizer exceeds a predetermined value. a steam turbine to which steam generated by an exhaust gas economizer, to which exhaust gas of an engine for power generation is induced, is induced;
a condenser for condensing the steam by guiding steam that has finished work in the steam turbine;
A vaporizer for heating and vaporizing liquefied gas;
An antifreeze circulation path connected to the carburetor and circulating antifreeze;
an antifreeze heating means for supplying heat from the condenser to the antifreeze circulating in the antifreeze circulation path;
A boiler that produces steam;
A steam heat exchanger for heat exchange between the steam generated in the boiler and the antifreeze circulating in the antifreeze circulation path;
A steam supply system for a turbine in which steam generated in the boiler is guided to the steam turbine;
A control unit for controlling the amount of steam induced to the steam turbine through the steam supply system for the turbine and the amount of steam induced to the steam heat exchanger
is provided,
The antifreeze heating means has a water circulation path through which water circulates and supplies heat from the condenser to the antifreeze circulation path,
The control unit reduces the amount of steam guided to the steam turbine and increases the amount of steam guided to the steam heat exchanger when the amount of liquefied gas vaporized in the vaporizer exceeds a predetermined value. According to claim 1,
A liquefied gas vaporizer having a seawater heat exchanger installed in the antifreeze circulation path and exchanging heat between the antifreeze and seawater after passing through the vaporizer. a steam turbine to which steam generated by an exhaust gas economizer, to which exhaust gas of an engine for power generation is induced, is induced;
a condenser for condensing the steam by guiding steam that has finished work in the steam turbine;
A vaporizer for heating and vaporizing liquefied gas;
An antifreeze circulation path connected to the carburetor and circulating antifreeze;
an antifreeze heating means for supplying heat from the condenser to the antifreeze circulating in the antifreeze circulation path;
A boiler that produces steam;
A steam heat exchanger for heat exchange between the steam generated in the boiler and the antifreeze circulating in the antifreeze circulation path;
A steam supply system for a turbine in which steam generated in the boiler is guided to the steam turbine;
A control unit for controlling the amount of steam induced to the steam turbine through the steam supply system for the turbine and the amount of steam induced to the steam heat exchanger
is provided,
The control unit reduces the amount of steam guided to the steam turbine and increases the amount of steam guided to the steam heat exchanger when the amount of liquefied gas vaporized in the vaporizer exceeds a predetermined value. According to claim 1,
a steam turbine generator driven by the steam turbine;
A circulation pump installed in the antifreeze circulation path;
A liquefied gas pump sending liquefied gas to the vaporizer
to provide,
A liquefied gas vaporizer for driving at least one of the circulation pump and the liquefied gas pump by the electric power generated by the steam turbine generator. The liquefied gas vaporization device according to claim 1;
Liquefied gas tank for storing liquefied gas
to provide,
The engine for power generation is operated by boil-off gas generated in the liquefied gas tank,
The vaporizer is a floating body facility for vaporizing the liquefied gas derived from the liquefied gas tank. delete delete delete

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