KR20180013101A - method and Air Cooling System of Gas Turbine - Google Patents

Abstract

The present invention provides an air cooling system of a gas turbine. The air cooling system of a gas turbine according to the present invention includes: an evaporating gas pressurization portion for pressurizing evaporative gas discharged from an LNG tank; a first heat exchanger for exchanging heat between extra pressurized evaporative gas supplied from the evaporative gas pressurization portion and the evaporative gas before the pressurization; a gas-liquid separator for separating the extra pressurized evaporative gas having passed through the first heat exchanger into gas and liquid via an expander; a second heat exchanger for exchanging heat between the evaporative gas liquefied in the gas-liquid separator and a circulating refrigerant; and a third heat exchanger for performing primary heat exchange between pressurized intake air and the circulating refrigerant.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas turbine,

The present invention relates to an air cooling method and apparatus for a gas turbine that cools the intake air of a gas turbine using evaporative gas.

In general, the ship will consume a lot of power. A gas turbine fueled by natural gas is used to cover the power required for the ship, and a steam turbine is installed at the rear end to produce additional electric power.

In order to increase the transportation efficiency of natural gas used for gas turbines, natural gas is cooled to -162 ° C to reduce its volume to one-sixth of that, and then the liquefied natural gas is stored in the storage tank and transported. Natural gas can be used as a fuel for a gas turbine after being vaporized in a vaporizer.

The gas turbine generator includes an air inlet, a compression section, a combustion section and a turbine, compressing the air introduced into the air inlet and mixing the fuel with the fuel, and then igniting the mixture of air and fuel in the combustion section to generate a hot gas Thereby driving the turbine.

These gas turbine generators are used to compensate for the insufficient power during the power consumption period, especially to compensate for the shortage of power generation facilities during the summer season, and to maximize the power consumption during very hot days, It is often used to meet power demands.

However, the output or thermal efficiency of the gas turbine generator is inversely proportional to the temperature of the incoming air supplied to the gas turbine generator. That is, when the atmospheric temperature is high, the air density required for combustion is lowered and the output of the gas turbine generator is lowered. In the summer when the atmospheric temperature is highest, the maximum output of the gas turbine is reduced by about 10% .

This fact has been known for many years in the turbine industry, and various devices and methods have been proposed to reduce the temperature of the air injected into the gas turbine generator to minimize the effects or disadvantages to the output of the gas turbine generator .

Conventionally, a fogging system is mainly used to reduce the temperature of air injected into a gas turbine generator. The fogging system is a system for cooling the combustion air by fogging the water using a separate chiller, evaporator, cooler and high-pressure nozzle.

However, conventional fogging systems can cause mechanical coupling of electrical components due to humidity changes, which can cause corrosion and damage of gas turbines, and can be used in areas with high latitudes or low temperatures The efficiency of the gas turbine can not be improved and the output of the gas turbine is unstable depending on the ambient temperature.

U.S. Patent No. 5,390,505

An object of the present invention is to provide an air cooling method and apparatus for a gas turbine that can increase the output of a gas turbine by utilizing the evaporation gas as a refrigerant to cool the incoming air for combustion of the gas turbine.

An object of the present invention is to provide a method and apparatus for cooling an air of a gas turbine that can prevent an icing phenomenon that may occur during the cooling process of inflow air for combustion.

 The problems to be solved by the present invention are not limited thereto, and other matters not mentioned can be clearly understood by those skilled in the art from the following description.

According to an aspect of the present invention, there is provided an evaporation apparatus comprising: an evaporation gas pressurizing unit that pressurizes evaporation gas generated from a liquefied gas storage tank; A first heat exchanger for heat-exchanging the pressurized extra evaporative gas, which is a part of the evaporated gas pressurized by the evaporated gas pressurized portion, with the pre-pressurized evaporative gas; A gas-liquid separator for separating the pressurized extra-volume evaporated gas, which has been heat-exchanged in the first heat exchanging unit, into a gas-state evaporated gas and a liquid-state evaporated gas through a vaporization process and a liquefaction process by an expander; A second heat exchanger for exchanging heat between the evaporated gas in the liquid state separated by the gas-liquid separator and the circulating refrigerant; And a third heat exchanger for exchanging the intake air flowing into the gas turbine with the circulating refrigerant.

In addition, the intake air may be one in which the outside air is pressurized by an external air pressurizer.

The gas-phase evaporation gas separated from the gas-liquid separator and the second heat-exchanging unit are subjected to heat exchange before the liquid-phase evaporation gas is introduced into the gas turbine before the intake air having undergone the heat exchange in the third heat- And a fourth heat exchanging unit for performing heat exchange with the mixed gas of the gaseous evaporated gas in the gas.

In addition, the mixed gas, which has undergone the heat exchange in the fourth heat exchanging part, and the evaporated gas pressurized in the evaporating gas pressing part may be mixed and introduced into the gas turbine.

A circulation line circulating the circulating refrigerant and passing through the second heat exchange unit and the third heat exchange unit; A refrigerant inflator provided on the circulation line for expanding the circulating refrigerant flowing from the third heat exchanging unit to the second heat exchanging unit; And a pump installed in the circulation line.

According to an aspect of the present invention, there is provided a method of operating a compressor, the method comprising: firstarily cooling a pressurized intake air which is pressurized by an external air pressurizer, And an evaporator for separating the evaporated gas in the gaseous state and the evaporated gas in the liquid state through the vaporization process and the liquefaction process by the expander, and the evaporated gas in the liquid state is heat-exchanged with the circulating refrigerant, And then cooling the pressurized intake air secondarily.

Further comprising the steps of: pressurizing the evaporative gas generated in the liquefied gas storage tank; And supplying the pressurized evaporated gas to the gas turbine, wherein the pressurized extra evaporative gas, which is a part of the pressurized evaporative gas, is heat-exchanged with the pre-pressurized evaporative gas.

Further, the pressurized extra-evaporative gas that has undergone heat exchange with the pre-pressurized evaporative gas is separated into an evaporated gas in a gaseous state and an evaporated gas in a liquid state via the inflator, and the evaporated gas in the liquid state is heat- Can be used.

Further, the evaporation gas used for the secondary cooling of the pressurized intake air may be supplied to the gas turbine by mixing with the pressurized evaporation gas.

According to the embodiment of the present invention, there is an effect of increasing the output and efficiency of the gas turbine by using the evaporation gas as a refrigerant to cool the inflow air for combustion of the gas turbine.

According to the embodiment of the present invention, the pressurized intake air is sequentially cooled in the third heat exchanger and the fourth heat exchanger, thereby preventing an icing phenomenon.

The effects of the present invention are not limited to the above-mentioned effects, and the effects not mentioned can be clearly understood by those skilled in the art from the present specification and the accompanying drawings.

1 is a conceptual diagram for explaining an air cooling system of a gas turbine according to a preferred embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention is capable of various modifications and various embodiments, and specific embodiments are illustrated in the drawings and will be described in detail in the detailed description. It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout the specification and claims. The description will be omitted.

1 is a conceptual diagram for explaining an air cooling system of a gas turbine according to a preferred embodiment of the present invention.

1, an air cooling system 10 of a gas turbine includes a liquefied gas storage tank 20, an evaporation gas pressurization unit 100, a first heat exchange unit 200, a gas-liquid separator 300, a second heat exchange unit A third heat exchanging part 500, and a fourth heat exchanging part 600. The first heat exchanging part 400, the third heat exchanging part 500,

In this specification, liquefied gas may refer to LNG, and LNG may be used to encompass both NG, which is a liquid state, and NG, such as a gas state, a supercooled state, and a supercritical state, May be used to mean a vaporized gas as well as a liquefied vaporized gas.

It should be understood that the present invention is not limited to the application to the ship as described in the background art, but may be applied to any equipment that can be installed on a ship, onshore, etc. and consumes LNG to produce power.

The liquefied gas storage tank 20 of an offshore structure stores cryogenic LNG to be supplied to a customer. The liquefied gas storage tank 20 must store the liquefied gas in a liquid state, in which case the liquefied gas storage tank 20 may have the form of a pressure tank. For reference, the liquefied gas storage tank 20 may include an outer tank (not shown), an inner tank (not shown), and a heat insulating portion (not shown). The outer tank may be formed of steel, and the outer tank may be made of stainless steel. The heat insulating portion is provided between the inner tank and the outer tank, and can prevent the external heat energy from being transmitted to the inner tank. In this specification, a marine structure is a concept that includes both a structure and a ship which are floated at sea while having a storage tank for storing liquid cargo which is loaded at a cryogenic temperature like LNG, for example, LNG FPSO (Floating, (LNG Regasification Vessel) as well as offshore structures such as production, storage, and offloading (LNG FSRU) and floating structures such as floating storage and regasification units (FSRU).

The evaporation gas generated in the liquefied gas storage tank 20 is supplied to the evaporation gas pressurization unit 100 through the evaporation gas line 22.

The evaporation gas pressurization section 100 may include a compressor 110 for compressing the evaporated gas discharged from the liquefied gas storage tank 20. The evaporated gas discharged from the evaporation gas pressurization unit 100 may have a pressure and a temperature required by the consumer. The pressurized evaporated gas whose temperature and pressure have been increased by compression in the evaporation gas pressurization section 100 is supplied to the gas turbine 900 as a customer through the main compression line 102 and is compressed in the evaporation gas pressurization section 100 A part of the evaporated gas or an extra evaporated gas of a capacity or more necessary for the generation can be supplied to the gas-liquid separator 300 through the first heat exchanger through the sub compression line 104.

Although not shown, a plurality of compressors 110 may be provided in series to pressurize the evaporation gas at multiple stages. For example, three compressors may be provided so that the evaporation gas is pressurized in three stages. Further, a plurality of compressors may be provided in parallel so that when one of the compressors is broken or can not be operated, another compressor So that the evaporation gas can be compressed smoothly to prevent the operation stop of the gas turbine.

The customer can include the gas turbine 900 and supply and consume the evaporated gas generated from the liquefied gas storage tank 20. The gas turbine 900 may combust the evaporation gas with compressed power generation intake air to rotate the turbine wheel (not shown). The gas turbine 900 may include a combustion section 910, an air compression section 920, a turbine section 930, and a generator 940.

The air compression unit 920 compresses the air supplied through the compressed air line 30 to generate intake air for power generation. The intake air for power generation is supplied to the combustion unit 910 and mixed with the evaporation gas to be burned , And drives the turbine section (930) and the generator (940). The turbine unit 930 and the air compressor 920 and the generator 940 may all be connected by a single shaft and the power generated by the generator 940 may be used to drive various devices or the like in the offshore structure, Can be used. That is, the gas turbine 900 is installed for power generation or power generation.

The first heat exchanging unit 200 exchanges the pressurized extra evaporation gas supplied from the evaporation gas pressurization unit 100 with the pre-pressurized evaporative gas. The first heat exchanger may heat the pressurized extra evaporated gas whose temperature has risen after compression with the pre-pressurized evaporative gas to improve the re-liquefaction efficiency. As an example, the pre-pressurized evaporative gas may have a temperature of about -120 degC, and the pressurized extra-evaporative gas may vary from design to design, but may have 30 bar and 100 degC.

That is, since the pressurized extra evaporation gas has a higher temperature than the pre-pressurized evaporative gas, the temperature of the pre-pressurized evaporative gas is increased through heat exchange with the pressurized extra evaporative gas in the first heat exchanging unit 200.

The pressurized extra evaporated gas having a lower temperature while passing through the first heat exchanging unit 200 is supplied to the gas-liquid separator 300. The gas-liquid separator 300 separates the pressurized extra-volume evaporative gas passing through the first heat exchanging unit 200 into gas and liquid via the expander, and the gaseous vaporized gas flows into the gas line 302, The re-liquefied evaporated gas) flows into the liquid line 304. The gas line 302 and the liquid line 304 may be combined together again and then connected to the main compression line 102 via the fourth heat exchanging part 600.

The liquid line 304 passes through the second heat exchanger 400. The second heat exchanging unit 400 exchanges heat between the liquid state evaporative gas and the circulating refrigerant. Here, the circulating refrigerant is in a state where the temperature is raised through heat exchange with the intake air in the third heat exchanger. In one example, the evaporation gas in liquid state (re-liquefied evaporation gas) may be 163 degC, the re-liquefied and the remaining evaporation gas may have a pressure and temperature of 3 bar, -150 degC to -120 degC. For example, when the evaporation gas in the liquid state is not sufficient to cool the circulating refrigerant, it can be cooled by decompression and expansion of the circulating refrigerant. Depending on the calculation result of the cooling efficiency, the circulating refrigerant may be decompressed and expanded after passing through the second heat exchanger, so that the order may be changed to enable further cooling.

That is, in the second heat exchanging unit 400, the evaporation gas in the liquid state is vaporized again through heat exchange with the circulating refrigerant, or the temperature rises after vaporization, and the temperature of the circulating refrigerant becomes low. The pressure and temperature of the circulating refrigerant are changed according to the type and flow rate of the refrigerant.

The circulating refrigerant is circulated along the circulation line 710. The circulation line 710 passes through the second heat exchanging part 400 and the third heat exchanging part 500. A refrigerant inflator 720 and a pump 730 may be installed in the circulation line 710. The refrigerant inflator 720 is disposed on a path from the third heat exchanging part 500 to the second heat exchanging part 400 to expand the circulating refrigerant. As the refrigerant inflator 720 expands the refrigerant, the circulating refrigerant can be cooled to a certain temperature while being reduced in pressure. That is, the circulating refrigerant is cooled step by step through the second heat exchanging part 400 and the refrigerant inflator 720, so that the pressurized intake air can be cooled at a lower temperature.

As the circulating refrigerant, it is preferable to use a material having a low freezing point, such as thermal oil (hot oil), glycol water, or evaporative refrigerant, so as not to be frozen by heat exchange with the LNG at cryogenic temperature. Thermal oil is a type of mineral oil that can be used over a very wide temperature range (-10 to 320 ° C). The glycol water is a mixture of glycol and water, and the mixing ratio thereof is about 30 to 50% of glycol and about 70 to 50% of water, and can be used also in a wide temperature range (-30 to 100 ° C).

The third heat exchanging part 500 performs primary heat exchange of the pressurized intake air using the circulating refrigerant. The outside air is pressurized by an air compressor installed in the compressed air line (30). Therefore, the temperature of the pressurized intake air after compression becomes higher than the temperature of the intake air before compression. For reference, the pre-compression intake air is equal to the ambient temperature and can have approximately 20-30 degC. The pressurized intake air having the increased temperature is firstly cooled by the circulating refrigerant in the third heat exchanging part (500). The temperature of the pressurized intake air through the primary cooling can be approximately 10 degC.

The pressurized sucked air primarily cooled in the third heat exchanging part (500) is secondarily cooled in the fourth heat exchanging part (600). The fourth heat exchanging unit 600 exchanges heat between the gaseous vaporized gas (re-liquefied and remaining vaporized gas) separated through the gas-liquid separator 300 and the circulating refrigerant in the second heat exchanging unit 400, Gas mixture is used to cool the pressurized intake air secondarily. The mixed vaporized gas is lower in temperature than the first cooled pressurized intake air, so it can be used as the cold of the pressurized intake air. For example, in the fourth heat exchanging part 600, the pressurized intake air is cooled to a temperature of -10 degC or cooled in a line where the relative humidity does not exceed 45% after cooling. The second cooled pressurized suction air is supplied to the air compression unit 920 of the gas turbine 900.

As described above, in the present invention, the pressurized intake air is cooled step by step in the third heat exchanging part 500 and the fourth heat exchanging part 600, thereby preventing water inflow and icing due to abrupt temperature change.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

20: Liquefied gas storage tank 100: Evaporating gas pressurizing unit
200: first heat exchanger 300: gas-liquid separator
400: second heat exchanger 500: third heat exchanger
600: fourth heat exchanger

Claims (9)

An evaporating gas pressurizing portion for pressurizing the evaporating gas generated from the liquefied gas storage tank;
A first heat exchanger for heat-exchanging the pressurized extra evaporative gas, which is a part of the evaporated gas pressurized by the evaporated gas pressurized portion, with the pre-pressurized evaporative gas;
A gas-liquid separator for separating the pressurized extra-volume evaporated gas, which has been heat-exchanged in the first heat exchanging unit, into a gas-state evaporated gas and a liquid-state evaporated gas through a vaporization process and a liquefaction process by an expander;
A second heat exchanger for exchanging heat between the evaporated gas in the liquid state separated by the gas-liquid separator and the circulating refrigerant; And
And a third heat exchanger for exchanging the intake air flowing into the gas turbine with the circulating refrigerant. The method according to claim 1,
Wherein the intake air pressurizes the outside air with an external air pressurizer. The method according to claim 1,
Wherein the gas-phase evaporation gas separated from the gas-liquid separator and the second heat-exchanging unit are heat-exchanged in the liquid-state evaporative gas before flowing the heat-exchanged intake air through the third heat exchanging unit into the gas turbine Further comprising a fourth heat exchange unit for exchanging heat with the mixed gas of the gaseous evaporated gas. The method of claim 3,
Wherein the mixed gas that has undergone heat exchange in the fourth heat exchanging unit and the evaporated gas pressurized by the evaporating gas pressurizing unit are mixed and introduced into the gas turbine. The method according to claim 1,
A circulation line for circulating the circulating refrigerant and passing through the second heat exchanger and the third heat exchanger;
A refrigerant inflator provided on the circulation line for expanding the circulating refrigerant flowing from the third heat exchanging unit to the second heat exchanging unit; And
And a pump installed in the circulation line. A step of firstly cooling the pressurized intake air which pressurized the intake air flowing into the gas inlet by the external air pressurizer using the circulating refrigerant; And
The evaporation gas in the gaseous state is separated into the evaporation gas in the gaseous state and the evaporation gas in the liquid state through the vaporization process and the liquefaction process by the expander, and the evaporation gas in the liquid state joins with the evaporation gas in the gaseous state through heat exchange with the circulating refrigerant And secondarily cooling the pressurized intake air. 7. The method of claim 6, further comprising: pressurizing the evaporative gas generated in the liquefied gas storage tank; And
Further comprising the step of supplying the pressurized evaporative gas to the gas turbine and heat exchanging the pressurized extra evaporative gas, which is a part of the pressurized evaporative gas, with the pre-pressurized evaporative gas. 8. The method of claim 7,
The pressurized extra-evaporative gas having undergone the heat exchange with the pre-pressurized evaporative gas is separated into an evaporated gas in a gaseous state and an evaporated gas in a liquid state via the inflator,
Wherein the evaporating gas in the liquid state is used for heat exchange with the circulating refrigerant. 8. The method of claim 7,
Wherein the evaporative gas used for the secondary cooling of the pressurized intake air is supplied to the gas turbine by mixing with the pressurized evaporative gas.

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