KR20200014502A - LNG Regasification System And Method - Google Patents

Abstract

The present invention relates to a liquefied natural gas regasification system and a method thereof, which can recover energy used in a high-pressure pump by using an expander so as to enable generation of additional electricity. Provided, in one embodiment of the present invention, is the liquefied natural gas regasification system comprising: a re-condenser which receives liquefied natural gas from a storage tank and evaporation gas generated in the correspondent storage tank to mix the same, thereby re-condensing the evaporation gas; a high-pressure pump which receives the liquefied natural gas from the re-condenser before compressing the same at a high pressure; an evaporator which evaporates the liquefied natural gas of a high pressure compressed in the high-pressure pump; an expander which expands the liquefied natural gas of a high pressure evaporated in the evaporator to decompress the same, while acquiring a rotating force from the energy upon decompression; a generator which generates electric energy by the rotating force of the expander; and a trim heater which increases the temperature reduced during the decompression process of the expander.

Description

LNG Regasification System And Method

The present invention relates to a liquefied natural gas regasification system and method, and more particularly, to a liquefied natural gas regasification system and method using an expander to recover the energy used in the high pressure pump to further power generation. .

As interest in environmentally friendly energy increases, the consumption of natural gas is rapidly increasing worldwide. Natural gas is transported in gaseous form through onshore or offshore gas piping, or transported to a distant consumer while stored in an LNG carrier (especially an LNG aqueous ship) in the form of liquefied natural gas. Liquefied natural gas is obtained by cooling natural gas to cryogenic temperature (approximately -163 ℃), and its volume is reduced to approximately 1/600 than natural gas in gas state, so it is very suitable for long distance transportation through sea.

The LNG Carrier is designed to unload liquefied natural gas to land requirements by loading the liquefied natural gas into the sea.For this purpose, an LNG storage tank (commonly referred to as a 'cargo') that can withstand the cryogenic temperature of liquefied natural gas It includes. Normally, such LNG carriers unload liquefied natural gas in LNG storage tanks on the land as they are liquefied, and the unloaded LNG is regasified by LNG regasification facilities installed on land and then transported through gas piping to consumers of natural gas. do.

In general, LNG plants such as FSRU and FSPP pressurize the BOG by using an LD compressor or a fuel gas compressor to process BOG from the LNG storage tank, and then pressurize the BOG through the LNG supply pump. Recondenser is mixed and recondensed with supercooled LNG. The recondensed LNG is pressurized by high pressure pump to natural gas delivery pressure or fuel gas supply pressure, and then heated / vaporized using heat exchanger to supply natural gas. Has a regasification system configured to supply

HP pump is designed according to the maximum pressure to cope with the variable delivery pressure. When the delivery pressure is low, the pressure is generally reduced by using a flow control valve (FCV) and then vaporized using a vaporizer.

However, if a certain level of operating pressure is required to ensure the performance of the carburetor, the pressure control valve (PCV) is used to maintain the pressure of the carburetor above the thermal design pressure, and finally, the pressure control valve (PCV) is used. It may also reduce the pressure to the delivery pressure.

When the difference between the design discharge pressure and the natural gas discharge pressure of the high pressure pump is large, the LNG or NG pressurized by consuming power is decompressed again through the flow control valve (FCV), thereby inefficiently using energy.

Republic of Korea Patent Publication No. 2015-0097966 (2015.08.27) "Liquid natural gas regasification system and method"

It is an object of the present invention to provide a system and method for regasification of liquefied natural gas that allows for the production of additional power by recovering energy used in a high pressure pump using an expander.

According to an embodiment of the present invention for achieving the above object, in the regasification system of liquefied natural gas, the liquefied natural gas and the evaporation gas generated from the storage tank is supplied and mixed to recondensate the boil-off gas Precondenser; A high pressure pump receiving liquefied natural gas from the recondenser and compressing the gas at high pressure; A vaporizer for vaporizing liquefied natural gas of high pressure compressed by the high pressure pump; An expander which expands the high pressure natural gas vaporized in the vaporizer and obtains rotational force with energy at reduced pressure while reducing pressure; A generator for producing electrical energy by the rotational force of the expander; And a trim heater that raises the temperature lowered in the depressurization process of the expander.

The regasification system of liquefied natural gas according to an embodiment of the present invention includes an inlet guide vane installed at an inlet side of the expander to adjust a flow rate supplied to the expander. Through the flow rate through the expander can be adjusted without changing the pressure.

Regasification system of liquefied natural gas according to an embodiment of the present invention may further include a pressure controller for changing the angle of the suction guide vane based on the pressure of the natural gas vaporized by the vaporizer.

In the regasification system of liquefied natural gas according to an embodiment of the present invention, a bypass valve (VB) for controlling an operating pressure of the vaporizer is installed, and the pressure controller is configured to have a predetermined minimum flow rate discharged from the vaporizer. When the reference flow rate is less than the opening degree of the bypass valve can be controlled.

The regasification system of liquefied natural gas according to an embodiment of the present invention may further include a return line for recovering the decompressed natural gas to the recondenser through the expander.

The return line may be provided with a recirculation valve for compensating the pressure of the recondenser.

Regasification system of liquefied natural gas according to an embodiment of the present invention may further include a flow rate controller for controlling the opening degree of the flow rate control valve installed between the high pressure pump and the vaporizer.

The expander may be installed in multiple stages.

The expander expands and decompresses a heated natural gas in a first heater to expand and decompress the high pressure natural gas regasified in the vaporizer and an intermediate heater heating the temperature of the decompressed natural gas through the first expander. It may include a second expander.

The regasification system of liquefied natural gas according to an embodiment of the present invention is connected to the first expander and the second expander, respectively, to generate electrical energy with the rotational force of the first expander and the second expander, respectively; And a second generator.

The regasification system of liquefied natural gas according to an embodiment of the present invention may further include a heat medium supply pump for supplying a heat medium for heating to the vaporizer and the trim heater, respectively.

The heat medium supply pump may supply a heat medium for heating to an intermediate heater for heating the temperature of the decompressed natural gas through the first expander.

According to another embodiment of the present invention, a method for regasifying a liquefied natural gas, comprising: compressing and regasifying the liquefied natural gas at a high pressure; Supplying the regasified high pressure natural gas to an expander; Expanding the high pressure natural gas in the expander to obtain a rotational force with energy at reduced pressure while reducing pressure; Producing electrical energy with the rotational force in a generator connected with the expander; And raising the temperature dropped during the depressurization of the expander.

Regasification method of liquefied natural gas according to another embodiment of the present invention after the step of supplying, receiving the pressure of the natural gas vaporized by the vaporizer; And changing an angle of the suction guide vane installed at the inlet of the expander based on the received pressure.

The supplying step includes receiving a flow rate discharged from the vaporizer; And controlling the opening degree of a bypass valve to control the operating pressure of the vaporizer when the received flow rate is less than a predetermined minimum reference flow rate.

The expander is installed in multiple stages, and the obtaining may include obtaining rotational force by a first expander which expands and decompresses the high-pressure natural gas regasified in the vaporizer; And obtaining rotational force by the second expander which expands and decompresses the heated natural gas in the intermediate heater heating the temperature of the decompressed natural gas through the first expander.

The producing step includes the steps of producing electrical energy with the rotational force obtained from the first expander; And producing electrical energy with the rotational force obtained from the second expander.

According to the embodiment of the present invention, it is possible to recover the energy used in the high pressure pump by using the expander to enable additional power generation.

In addition, according to an embodiment of the present invention, as the suction guide vane is installed at the inlet side of the expander, it is possible to adjust the flow rate supplied to the expander by changing the angle of the suction guide vane without changing the pressure.

In addition, according to an embodiment of the present invention, when the expander is installed in multiple stages, the supply flow rate of the heating medium for heating is increased as compared to a single expander, but the amount of electrical energy produced is offset even to this effect, enabling the efficient use of energy. have.

1 is a view for explaining a regasification system of liquefied natural gas according to an embodiment of the present invention.
2 is a view for explaining a regasification system of liquefied natural gas according to another embodiment of the present invention.
3 is a graph showing the relationship between the opening degree and the flow rate of the flow control valve and the suction guide vane.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a view for explaining a regasification system of liquefied natural gas according to an embodiment of the present invention.

Referring to FIG. 1, a regasification system of liquefied natural gas according to an exemplary embodiment of the present invention includes LNG supplied from a storage tank (not shown) for storing LNG and boil off gas generated from the corresponding storage tank (BOG). Recondenser (10) for receiving and mixing the re-condensation of the boil-off gas, a high-pressure pump (20) for receiving the liquefied natural gas from the re-condenser 10 and compressed to high pressure, and a high-pressure pump (20) Vaporizer 30 for vaporizing the liquefied natural gas compressed in the air, expander 40 which expands the high-pressure natural gas regasified by the vaporizer 30 and obtains rotational force with energy at reduced pressure, and expander 40. It includes a generator 42 for producing electrical energy by the rotation force obtained in the) and the trim heater 50 for raising the temperature dropped during the decompression process of the expander 40.

In addition, the regasification system of liquefied natural gas according to an embodiment of the present invention is installed at the inlet of the expander 40, suction guide vanes (IGV: Inlet Guide Vane, hereinafter for adjusting the flow rate supplied to the expander 40) It may be configured to include (IGV) 41).

The recondenser 10 recondenses the boil-off gas by mixing the LNG (eg, 790.5 MMSCFD) and the boil-off gas (eg, 9.5 MMSCFD) supplied from the storage tank. The recondenser 10 supplies the liquefied natural gas (eg, 4 barg, -160 ° C.) not containing gas to the high pressure pump 20.

The recondenser 10 may perform a function of a suction drum as a function of mixing LNG and boil-off gas, and may perform a function of a gas-liquid separator as a function of separating gas and liquid from the suction drum. .

The high pressure pump 20 receives the liquefied natural gas from the recondenser 10 and compresses it to high pressure. The high pressure pump 20 compresses the liquefied natural gas to high pressure using approximately 7,141 kw of electric energy.

The high pressure liquefied natural gas (for example, 125 barg, -151 ° C) compressed by the high pressure pump 20 is supplied to the vaporizer 30.

Between the high pressure pump 20 and the vaporizer 30, a flow control valve FCV is installed. The valve for controlling the flow rate FCV is controlled by the flow rate controller FIC 25.

The flow rate controller 25 controls the opening degree of the flow rate control valve FCV to adjust the flow rate of the liquefied natural gas supplied to the vaporizer 30.

Particularly, when the flow rate of the vaporizer 30 is lower than the inflow flow rate, the flow rate controller 25 decompresses the liquefied natural gas pressurized by the high pressure pump 20 from the flow rate control valve FCV to supply the vaporizer. Control the opening degree of (FCV).

When the vaporizer 30 is operated at the designed discharge pressure of the high-pressure pump 20 or when the operating pressure of the vaporizer 30 is equal to or greater than the reference pressure, the pressure controller (PIC) 35 is not a valve such as PCV, but the expander 40. The operating pressure of the vaporizer 30 is further controlled by changing the angle of the IGV 41 installed at the inlet of the vaporizer.

More specifically, the pressure controller (PIC) 35 reduces the flow rate through the expander 40 based on the outlet pressure from the vaporizer 30 so as to reduce the discharge pressure using the expander 40. Adjust by changing the angle of the IGV 41 installed at the inlet of.

Afterwards, the trim heater 50 heats the temperature of the decompressed natural gas to compensate for this by enlarging a large temperature drop in the isotropic expansion process since the decompression process of the expander 40 is performed after the vaporizer 30.

The vaporizer | carburetor 30 vaporizes the liquefied natural gas of high pressure through heat exchange with the heat medium for heating supplied by the heat medium supply pump 5.

Natural gas (eg, 122.5 barg, 8 ° C.) vaporized by the vaporizer 30 is supplied from the expander 40.

The amount of natural gas supplied to the expander 40 is adjusted by the IGV 41 provided at the inlet of the expander 40. That is, the angle of the IGV 41 including a wing like a grain shape around the lower rotor at the inlet side of the expander 40 is changed, that is, the angle of the wing.

The angle of the IGV 41 is controlled by the pressure controller PIC based on the pressure of the natural gas vaporized by the vaporizer 30.

In the case of the valve, the flow path shape is almost the same, but the pressure drop occurs more greatly than the flow rate control performance because the flow path size is adjusted. However, the IGV 41 controls the flow path flow rate through the expander 40. Because of the reduction, pressure drop does not occur much like a valve, which is more effective.

Natural gas (eg, 50.5 barg, −39 ° C.) depressurized by the expander 40 is supplied to at least one of the recondenser 10 and the trim heater 50.

If necessary to compensate for the operating pressure of the recondenser 10, the natural gas reduced by the expander 40 may be returned to the recondenser 10 through the return line (L1).

When pressure compensation of the recondenser 10 is necessary, the opening degree of the recirculation valve RV installed in the return line L1 is adjusted so that a part of the natural gas decompressed by the expander 40 is supplied to the recondenser 10. When the pressure compensation of the recondenser 10 is unnecessary, all natural gas decompressed by the expander 40 is supplied to the trim heater 50.

The trim heater 50 raises the temperature lowered during the depressurization of the expander 40 in order to meet the minimum natural gas discharge temperature. At this time, the heating medium is also supplied to the trim heater 50 by the heating medium supply pump 5.

The heating heating medium supplied to the vaporizer 30 and the trim heater 50 through the heating medium supply pump 5 may be, for example, about 3111 kW.

The generator 42 produces electric energy by the rotational force of the expander 40. The expander 40 and the generator 42 are connected by a drive shaft, and converts the rotational force obtained from the expander 40 into electrical energy in the generator 42 to obtain electric power.

In the expander 40, the natural gas is reduced in pressure required by the natural gas consumer while gaining rotational force through the high pressure natural gas.

The natural gas consumer may be, for example, a cogeneration plant, various offshore or onshore power plants, a gas supply plant, an engine, or the like.

When the liquefied natural gas is compressed to 50 barg or more, preferably 70 barg or more, which is higher than the critical pressure, in order to increase the heat exchange efficiency of the vaporizer 30, the cogeneration plant is a consumer of vaporized natural gas. Since the required pressure is about 30 to 40 barg, the high pressure natural gas should be decompressed according to the required pressure, and the present embodiment expands the high pressure natural gas by the corresponding pressure to reduce the pressure and obtain rotational force.

In particular, the flow rate supplied to the expander 40 is adjusted by changing the angle of the IGV 41. Therefore, in the prior art, if the difference between the delivery pressure of the natural gas passed through the vaporizer 30 and the designed discharge pressure of the high-pressure pump is large, the liquefied natural gas or natural gas that is consumed by pressurizing the power is reduced again through a valve such as FCV. Although energy was inefficiently used, the regasification system of the liquefied natural gas of the present invention reduces the flow rate through the expander 40 by adjusting the shape of the flow path through the IGV 41 installed at the inlet side of the expander 40. Because it is more effective.

By providing the expander 40 and the bypass valve BV in place of the valve such as PCV at the rear end of the vaporizer 30, the vaporizer 30 can be controlled to operate at a stable pressure even if the delivery pressure is lowered.

The pressure controller PIC controls the minimum uncontrollable capacity of the expander 40 to the IGV 41 to be supplied to the trim heater 50 or the natural gas consumer via the bypass valve BV, or to the IGV 41 of the expander 40. The controllable capacity at 41 is controlled to be supplied to the expander 40 without passing through the bypass valve BV.

The pressure controller 35 may control the opening degree of the IGV 41 and the opening degree of the bypass valve BV as shown in the graph of FIG. 3. In general, since the flow rate of less than about 20% cannot flow to the rated flow rate of the expander 40, the opening degree of the bypass valve BV is controlled while the opening degree of the IGV 41 is controlled.

When the expander 40 is not operated, the pressure controller 35 independently controls the bypass valve BV for controlling the operating pressure of the vaporizer 30. The bypass valve BV is started when the expander 40 is under maintenance, or the flow rate is less than approximately 20%, or when the inlet pressure of the expander 40 is not sufficient at initial startup. The initial start is started by manually adjusting the opening degree of the bypass valve BV with the expander 40 turned off. In an environment in which the expander 40 is not operated, the angle of the IGV 41 may be changed so that the natural gas vaporized by the vaporizer 30 is not supplied to the expander 40.

The bypass valve BV is a means for controlling the operating pressure of the vaporizer 30, and the opening degree is controlled by the pressure controller 35. The pressure controller 35 controls the opening degree of the bypass valve BV when the flow rate flowing out of the vaporizer 30 is less than a predetermined minimum reference flow rate, for example, 20%, so that the pressure of the vaporizer 30 can maintain a safe pressure. Make sure

According to the regasification system of the liquefied natural gas of the present invention, by providing the expander 40 and the bypass valve (BV) at the rear end of the vaporizer 30, even if the discharge pressure of the vaporizer 30 is lowered, the vaporizer 30 is stable It is controlled to operate at the pressure, it can be produced additional electrical energy by the rotational force generated in the process of decompression to the final delivery pressure in the expander (40).

Conventionally, when the discharge pressure of the carburetor is low, the liquefied natural gas pressurized by consuming the power in the high pressure pump is decompressed in the flow rate control process of the flow control valve, the energy is discarded, but according to an embodiment of the present invention The regasification system of liquefied natural gas recovers energy by decompressing the energy used in the high pressure pump 20 to the delivery pressure in an isenthalpic process using the expander 40, and using the generator 42 to recover the energy. By producing the power through it to recover the energy used in the high-pressure pump 20 and further enables further power production.

Natural gas (eg, 50 barg, 8 ° C.) heated by the trim heater 50 is supplied to the natural gas consumer.

Referring to the regasification method of liquefied natural gas according to an embodiment of the present invention having such a configuration as follows.

First, the recondenser 10 receives LNG and boil off gas from a storage tank storing LNG, respectively, and condenses the boil off gas by mixing the supplied LNG and boil off gas.

The high pressure pump 20 compresses the liquefied natural gas supplied from the recondenser 10 to a high pressure up to a predetermined design pressure.

The vaporizer 30 vaporizes the pressurized liquefied natural gas through the high pressure pump 20 and supplies the vaporized natural gas to the expander 40.

At this time, the pressure of the vaporizer 30 is controlled by the flow rate controller 25 and the pressure controller 35 to maintain the operating pressure. More specifically, in the state where the flow rate supplied to the vaporizer 30 by the flow controller 25 is controlled by adjusting the opening degree of the flow control valve FCV, the pressure controller 35 expands the vaporizer 30 from the vaporizer 30. The operating pressure of the vaporizer 30 may be changed by adjusting the angle of the IGV 41 installed at the inlet of the expander 40 to adjust the flow rate passing through the 40.

The expander 40 expands and decompresses the high pressure natural gas vaporized in the vaporizer 30.

The trim heater 50 heats the temperature dropped during the decompression process of the expander 40. The natural gas heated by the trim heater 50 described above is supplied to the natural gas consumer.

The generator 42 produces electrical energy with the rotational force obtained by the energy generated during the decompression process of the expander 40. The electrical energy produced by the generator 42 described above may be distributed to various power consumption units (not shown) of the ship or offshore structure through the switchboard.

Hereinafter, a regasification system of liquefied natural gas according to another exemplary embodiment of the present invention having a multistage expander will be described.

2 is a view illustrating a regasification system of liquefied natural gas according to another embodiment of the present invention.

2, the regasification system of liquefied natural gas according to another embodiment of the present invention in multiple stages through the intermediate heater 60 without decompressing to the final discharge pressure at once to increase the amount of work recovered from the expander 40 It includes a configuration to reduce the pressure using the installed expander (40, 45).

Among the expanders installed in multiple stages, the first expander 40 has the same member number as that of the above-described expander, and the second expander 45 is located at a different position from the first expander 40 and the first expander 40. The natural gas heated by the intermediate heater 60 is reduced in pressure.

The first expander 40 expands and decompresses the natural gas (eg, 122.5 barg, 8 ° C.) supplied from the vaporizer 30, and obtains rotational force by energy at the time of decompression.

A first IGV 41 is installed at the inlet of the first expander 40 to adjust the flow rate supplied to the first expander 40. The first IGV 41 is controlled by the first pressure controller 35. The first pressure controller 35 controls the opening degree of the first IGV 41 and the opening degree of the first bypass valve BV1 as shown in the graph of FIG. 3.

Natural gas (eg, 78 barg, −18.8 ° C.) depressurized by the first expander 40 is supplied from the intermediate heater 60.

The intermediate heater 60 heats the temperature of the natural gas decompressed by the first expander 40 and is supplied to the second expander 45. In this case, the intermediate heater 60 may increase the work recovered from the first expander 40.

The second expander 45 expands and decompresses the natural gas (for example, 77.5 barg, 8 ° C.) supplied by heating the temperature of the natural gas by the intermediate heater 60, and obtains a rotational force by energy at the reduced pressure. .

A second IGV 43 is installed at the inlet of the second expander 45 to adjust the flow rate supplied to the second expander 45. The second IGV 43 is controlled by the second pressure controller 65.

The second pressure controller 65 controls the opening degree of the second IGV 43 and the opening degree of the second bypass valve BV2 as shown in the graph of FIG. 3.

The trim heater 50 is heated by receiving a natural gas (eg, 50.5 barg, -17.4 ° C.) reduced in pressure by the second expander 45.

Natural gas (eg, 50 barg, 8 ° C.) heated by the trim heater 50 is supplied to the natural gas consumer.

More specifically, the regasification system of liquefied natural gas according to another embodiment of the present invention is the first expander 40 and the intermediate heater 60, which is located between the vaporizer 30 and the intermediate heater 60 described above; A second expander 45 located between the trim heaters 50, and the first and second expanders 40 and 45 each include a generator that produces electrical energy by the rotational force obtained from the expander, that is, the first expander. The first generator 42 which produces electrical energy by the rotational force of 40, and the 2nd generator 46 which produces electrical energy by the rotational force of the 2nd expander 45 are comprised.

At this time, the heat medium for heating is supplied to the vaporizer | carburetor 30, the intermediate | middle heater 60, and the trim heater 50 via the heat medium supply pump 5, respectively.

The heat medium supplied to the vaporizer 30, the intermediate heater 60, and the trim heater 50 through the heat medium supply pump 5 is, for example, about 1,139 kW, and in the previous embodiment, the vaporizer 30 and the trim heater 50 are provided. The supply amount is larger than the amount of the heating medium for heating. However, assuming that the amount of electric energy produced using a single expander is 10,710 kW, for example, the multi-stage expander, that is, the amount of electric energy generated using the first expander 40 is, for example, 5.850 kW and the second expander 45 is used. Since the amount of electric energy produced by using is 6,320 kW, for example, the supply amount of the heating medium for heating is partially increased than that of the liquefied natural gas regasification system shown in FIG. It can be seen that the amount of electrical energy produced by the connected first and second generators 42 and 46, respectively, is more than offset.

Such a regasification system of the present embodiment may be provided in a ship or offshore structure including a regasification vessel (RV) and a floating storage regasification unit (FSRU), in which case in the carburetor 30 in a ship or offshore structure instead of the heating medium. Using seawater with easy intake, liquefied natural gas can be regasified through heat exchange with seawater.

The electrical energy produced by the first and second generators 42 and 46 may be distributed to various power consumption units (not shown) of the ship or offshore structure through the switchboard.

The regasification method using the regasification system of liquefied natural gas according to another embodiment of the present invention, in the regasification of liquefied natural gas, the liquefied natural gas is compressed and vaporized to a high pressure, and the vaporized high pressure natural gas While expanding in the first expander 40 to reduce the pressure to the required pressure to obtain a rotational force with the energy at the time of decompression, the natural gas reduced in the first expander 40 is heated in the intermediate heater 60, in the intermediate heater 60 The heated natural gas is expanded in the second expander 45 supplied with the heated gas to reduce the pressure to the required pressure of the natural gas consumer, thereby obtaining rotational force with energy at the reduced pressure, and trimming the temperature of the natural gas reduced in the second expander 45. Lifted by 50 and produces electrical energy with rotational force in a first generator 42 connected to the first expander 40, and in a second generator 46 connected to the second expander 45. The production of electrical energy into power. Therefore, the electric energy produced by the first and second generators 42 and 46 is supplied to the power consumption necessary in the ship or the plant itself, and the natural gas passed through the trim heater 50 is supplied to the natural gas consumer. Done.

In particular, by varying the angles of the first and second IGVs 41, 43 provided at the inlets of the first and second expanders 40, 45, the flow rates supplied to the first and second expanders 40, 45. Can be adjusted without pressure change.

By using the first and second expanders 40 and 45 installed in multiple stages as described above, the energy of natural gas during decompression is recovered and produced as electric energy to supply the necessary power in the plant, thereby minimizing wasted energy. , Increase energy efficiency, reduce operating costs and increase economics.

The present invention is not limited to the above described embodiments, and various modifications and changes can be made by those skilled in the art, which are included in the spirit and scope of the present invention as defined in the appended claims.

5: heat medium supply pump 10: recondenser
20: high pressure pump 30: vaporizer
40: Expander 41: suction guide vanes
42: generator 50: trim heater
60: intermediate heater

Claims (17)

In the regasification system of liquefied natural gas,
A recondenser for receiving the liquefied natural gas and the evaporated gas generated from the storage tank and mixing the storage tank to recondense the boiled gas;
A high pressure pump receiving liquefied natural gas from the recondenser and compressing the gas at high pressure;
A vaporizer for vaporizing liquefied natural gas of high pressure compressed by the high pressure pump;
An expander which expands the high pressure natural gas vaporized in the vaporizer and obtains rotational force with energy at reduced pressure while reducing pressure;
A generator for producing electrical energy by the rotational force of the expander; And
And a trim heater that raises the temperature lowered in the depressurization process of the expander. The method according to claim 1,
It is installed at the inlet side of the expander, including an inlet guide vane (Inlet Guide Vane) for adjusting the flow rate supplied to the expander, to adjust the flow rate passing through the expander through the suction guide vane, without pressure change, liquefaction Natural gas regasification system. The method according to claim 2,
And a pressure controller for varying the angle of the suction guide vanes based on the pressure of the natural gas vaporized by the vaporizer. The method according to claim 3,
Bypass valve (VB) for controlling the operating pressure of the carburetor is installed,
The pressure controller controls the opening degree of the bypass valve when the flow rate flowing out of the vaporizer is less than a predetermined minimum reference flow rate. The method according to claim 1,
And a return line for recovering the decompressed natural gas via the expander to the recondenser. The method according to claim 5,
The return line is provided with a recirculation valve for compensating the pressure of the recondenser, liquefied natural gas regasification system. The method according to claim 1,
And a flow rate controller for controlling the opening degree of the flow rate control valve installed between the high pressure pump and the vaporizer. The method according to claim 1,
The expander is installed in multiple stages, liquefied natural gas regasification system. The method according to claim 8,
The expander expands and decompresses a heated natural gas in a first heater to expand and decompress the high pressure natural gas regasified in the vaporizer and an intermediate heater heating the temperature of the decompressed natural gas through the first expander. A regasification system of liquefied natural gas, comprising a second expander. The method according to claim 9,
And a first and second generators connected to the first expander and the second expander, respectively, to generate electrical energy by the rotational force of the first expander and the second expander, respectively. . The method according to claim 1,
And a heat medium supply pump for supplying a heat medium for heating to the vaporizer and the trim heater, respectively. The method according to claim 11,
The heat medium supply pump supplies a heat medium for heating to the intermediate heater for heating the temperature of the natural gas decompressed through the first expander, regasification system of liquefied natural gas. In the regasification method of liquefied natural gas,
Compressing and regasifying the liquefied natural gas at high pressure;
Supplying the regasified high pressure natural gas to an expander;
Expanding the high pressure natural gas in the expander to obtain a rotational force with energy at reduced pressure while reducing pressure;
Producing electrical energy with the rotational force in a generator connected with the expander; And
Raising the temperature dropped in the process of decompressing the expander, natural gas regasification method. The method according to claim 13,
After the feeding step,
Receiving a pressure of natural gas vaporized by the vaporizer; And
Changing the angle of the suction guide vane installed at the inlet of the expander based on the received pressure. The method according to claim 13,
The supplying step
Receiving a flow rate flowing out of the vaporizer; And
And controlling the opening degree of the bypass valve to control the operating pressure of the vaporizer when the received flow rate is less than a predetermined minimum reference flow rate. The method according to claim 13,
The expander is installed in multiple stages,
The obtaining step
Obtaining rotational force by a first expander which expands and decompresses the high-pressure natural gas regasified in the vaporizer; And
Obtaining a rotational force by a second expander which expands and decompresses the heated natural gas in an intermediate heater heating the temperature of the decompressed natural gas through the first expander. The method according to claim 16,
The producing step
Producing electrical energy with the rotational force obtained from the first expander; And
And producing electrical energy with the rotational force obtained from the second expander.

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