KR102474275B1 - Combined power plant and operating method of the same - Google Patents

Abstract

In a combined power generation system according to an aspect of the present invention, a gas turbine generating rotational force by burning fuel and a high pressure part, a medium pressure part, and a low pressure part having different pressure levels are heated by using combustion gas discharged from the gas turbine. a heat recovery boiler having a heat recovery boiler, a fuel preheater that heats the fuel supplied to the gas turbine and has a primary heating unit and a secondary heating unit, a high-pressure water supply pipe connected to the high-pressure unit and supplying high-pressure water to the secondary heating unit, and the secondary heating unit. A water delivery pipe that connects the heating unit and the primary heating unit to supply the water discharged from the secondary heating unit to the primary heating unit, and is connected to a downstream side of the intermediate pressure water supply pump of the intermediate pressure unit to supply water discharged from the secondary heating unit to the primary heating unit. A water supply temperature control pipe for supplying water, and a water supply pressure control pipe connected to the intermediate pressure unit to supply medium-pressure water to the water delivery pipe and supplying second medium-pressure water having a temperature higher than that of the first medium-pressure water supply. can

Description

Combined power generation system and driving method of the combined power generation system {COMBINED POWER PLANT AND OPERATING METHOD OF THE SAME}

The present invention relates to a combined power generation system and a driving method of the combined power generation system. More specifically, the present invention relates to a combined power generation system having a gas turbine and a fuel preheater and a method of driving the combined power generation system.

A combined power generation system is a power generation system configured by combining a gas turbine and a steam turbine with high efficiency to guide high-temperature exhaust gas from the gas turbine to a heat recovery boiler (HRSG) and generate steam by using thermal energy retained in the exhaust gas. This steam enables power generation by the steam turbine and can be combined with the power generated by the gas turbine to improve the thermal efficiency equivalent to the thermal energy retained in the exhaust gas compared to stand-alone power production by the gas turbine. .

A gas turbine is a power engine that mixes and burns compressed air compressed by a compressor with fuel, and rotates the turbine with high-temperature gas generated by combustion. Gas turbines are used to drive generators, aircraft, ships and trains.

In order to improve the efficiency of a gas turbine, it is necessary to preheat fuel introduced into the gas turbine. The temperature of the gas turbine increases as the fuel is preheated to a high temperature, but when the fuel is overheated, a problem of carbonization due to thermal decomposition may occur during the process of preheating the fuel.

Based on the technical background as described above, the present invention provides a combined power generation system capable of efficiently preheating fuel supplied to a gas turbine and a driving method of the combined power generation system.

In a combined power generation system according to an aspect of the present invention, a gas turbine generating rotational force by burning fuel and a high pressure part, a medium pressure part, and a low pressure part having different pressure levels are heated by using combustion gas discharged from the gas turbine. a heat recovery boiler having a heat recovery boiler, a fuel preheater that heats the fuel supplied to the gas turbine and has a primary heating unit and a secondary heating unit, a high-pressure water supply pipe connected to the heat recovery boiler and supplying water to the secondary heating unit; A feed water delivery pipe that connects the primary heating unit and the primary heating unit to supply water discharged from the secondary heating unit to the primary heating unit, and is connected to the heat recovery boiler to supply first water supply to the feed water delivery pipe A feed water temperature control pipe and a feed water pressure control pipe connected to the heat recovery boiler to supply water to the feed water delivery pipe and supplying second feed water having a higher temperature than the first feed water, wherein the feed water delivery pipe includes: A connection portion is formed in which the water supply temperature control pipe, the water supply delivery pipe, and the water supply pressure control pipe are connected, and between the primary heating unit and the secondary heating unit to control the flow rate of high-pressure water supply flowing into the secondary heating unit. An intermediate control valve may be installed, and the intermediate control valve may be located between the connection part and the secondary heating part.

According to one aspect of the present invention, the high-pressure unit includes a high-pressure economizer for heating feed water, a high-pressure drum for storing the feed water heated in the high-pressure economizer, and a high-pressure evaporator for heating water in the high-pressure drum and converting it into steam, The high-pressure water supply pipe may be connected between the high-pressure economizer and the high-pressure drum to receive water heated by the high-pressure economizer.

In the combined power generation system according to an aspect of the present invention, a feed water recovery pipe for transferring the feed water discharged from the primary heating unit to the heat recovery boiler and a feed water recovery pipe are installed to control the flow rate of the feed water discharged from the primary heating unit. It may further include a downstream control valve that

According to one aspect of the present invention, the intermediate pressure unit includes an intermediate pressure pump that pressurizes and moves the water supply, an intermediate pressure economizer that receives water from the intermediate pressure pump and heats the water supply, and an intermediate pressure drum that stores the water heated by the intermediate pressure economizer, , Excess high-pressure feed water discharged from the primary heating unit by the downstream control valve may be supplied to the intermediate pressure drum through the feed water pressure control pipe.

Combined power generation system according to an aspect of the present invention connects the upstream of the primary heating unit and the downstream of the secondary heating unit, bypasses the primary heating unit and the secondary heating unit, and supplies fuel downstream of the secondary heating unit. It may further include a bypass pipe for moving and a fuel control valve for controlling the flow rate of the fuel moving through the bypass pipe.

A combined power generation system according to an aspect of the present invention connects upstream of the primary heating unit and upstream of the secondary heating unit, and bypasses the primary heating unit to move fuel to the secondary heating unit and the bypass pipe. A fuel control valve for controlling the flow rate of fuel moving through the pass pipe may be further included.

An intermediate pressure control valve for adjusting the flow rate of the water supplied from the water supply temperature control pipe to the water delivery pipe may be installed in the water supply temperature control pipe according to an aspect of the present invention.

According to another aspect of the present invention, a gas turbine, a steam turbine, a heat recovery boiler, and a fuel preheater having a primary heating unit and a secondary heating unit for preheating fuel, wherein the heat recovery boiler includes a low pressure unit, a medium pressure unit, and a high pressure unit. A method of driving a combined power generation system comprising: supplying feedwater heated by the heat recovery boiler to the secondary heating unit, and supplying the feedwater discharged from the secondary heating unit and the first feedwater supplied from the heat recovery boiler to the secondary heating unit. A fuel preheating step of mixing second water having a temperature higher than that of the first water supply and supplying it to the primary heating unit, a water supply pressure determination step of measuring the pressure of the water supply between the primary heating unit and the secondary heating unit, A fuel temperature determination step of measuring the temperature of the fuel discharged from the secondary heating unit and comparing it with a reference temperature, and controlling the pressure of the supply water using a downstream control valve that controls the flow rate of the supply water discharged from the primary heating unit. a pressure control step; and a fuel temperature control step of controlling the temperature of the fuel by adjusting an intermediate control valve that controls the movement of feed water between the primary heating unit and the secondary heating unit, wherein the fuel preheating step includes a secondary heating unit. The water supply discharged from the heating part, the first water supply, and the second water supply may be joined at a connection part formed in the water supply pipe, and the intermediate control valve may be positioned between the connection part and the secondary heating part.

In the fuel preheating step according to another aspect of the present invention, water may be supplied to the secondary heating unit through a high-pressure water supply pipe connected between the high-pressure economizer and the high-pressure drum of the high-pressure unit.

The water supply pressure control step according to another aspect of the present invention reduces the opening of the downstream control valve when the pressure of the water supply moving from the secondary heating unit to the primary heating unit is lower than a preset reference pressure, and When the pressure of the supply water moving from the primary heating unit to the primary heating unit is higher than a preset reference pressure, the opening degree of the downstream control valve may be increased.

When the opening of the downstream control valve is reduced in the water supply pressure control step according to another aspect of the present invention, some of the water discharged from the secondary heating unit moves to the middle pressure unit through the water supply pressure control pipe, When the opening degree of the downstream control valve is increased in the water supply pressure control step, the second water supply may move to the water supply delivery pipe through the water supply pressure control pipe.

The fuel temperature control step according to another aspect of the present invention increases the opening of the intermediate control valve when the temperature of the fuel discharged from the secondary heating unit is lower than a preset reference temperature, and discharges from the secondary heating unit. When the temperature of the fuel is higher than the preset second reference temperature, the opening degree of the intermediate control valve may be reduced.

The fuel temperature control step according to another aspect of the present invention bypasses the primary heating unit and the secondary heating unit and adjusts the fuel control valve installed in the bypass pipe for supplying fuel to the downstream side of the secondary heating unit to control the fuel temperature. The temperature is adjusted, but when the temperature of the fuel discharged from the secondary heating unit is lower than the preset second reference temperature, the opening degree of the fuel control valve is reduced, and when the fuel control valve is closed, the intermediate control valve The opening degree is increased, and when the temperature of the fuel discharged from the secondary heating part is higher than the second reference temperature, the opening degree of the fuel control valve is increased, and when the fuel control valve is completely opened, the intermediate control valve Openness can be reduced.

As described above, the combined power generation system according to one aspect of the present invention includes a feed water delivery pipe, a feed water temperature control pipe, and a feed water pressure control pipe, so that the temperature of the fuel and the pressure of the feed water can be easily controlled.

In addition, in the combined power generation system according to one aspect of the present invention, since the connection part is formed and the pressure is determined at the connection part, reverse flow can be reliably prevented by controlling the pressure at the connection part based on the pressure. In addition, since the intermediate control valve is located between the connection part and the secondary heating part, it is possible to reliably control the inflow and pressure of the water supply using the intermediate control valve.

1 is a configuration diagram showing a combined power generation system according to a first embodiment of the present invention.
2 is a configuration diagram showing a fuel preheater and an exhaust heat recovery boiler according to a first embodiment of the present invention.
3 is a configuration diagram showing a fuel preheater according to a first embodiment of the present invention.
4 is a flowchart illustrating a method of driving a combined power generation system according to a first embodiment of the present invention.
5 is a configuration diagram showing a fuel preheater according to a second embodiment of the present invention.
6 is a configuration diagram showing a fuel preheater according to a third embodiment of the present invention.

Since the present invention can apply various transformations and have various embodiments, specific embodiments will be exemplified and described in detail in the detailed description. However, it should be understood that this is not intended to limit the present invention to specific embodiments, and includes all transformations, equivalents, and substitutes included in the spirit and scope of the present invention.

Terms used in the present invention are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In the present invention, terms such as 'include' or 'having' are intended to designate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, but one or more other features It should be understood that the presence or addition of numbers, steps, operations, components, parts, or combinations thereof is not precluded.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. At this time, it should be noted that in the accompanying drawings, the same components are indicated by the same reference numerals as much as possible. In addition, detailed descriptions of well-known functions and configurations that may obscure the gist of the present invention will be omitted. For the same reason, in the accompanying drawings, some components are exaggerated, omitted, or schematically illustrated.

Hereinafter, a gas turbine according to a first embodiment of the present invention will be described.

1 is a configuration diagram showing a combined power generation system according to a first embodiment of the present invention, FIG. 2 is a configuration diagram showing a fuel preheater and a heat recovery boiler according to a first embodiment of the present invention, and FIG. It is a configuration diagram showing the fuel preheater according to the first embodiment of the present invention.

Referring to FIGS. 1 to 3 , the combined power generation system 100 according to the first embodiment includes a plurality of turbines and generates electric power. The combined power generation system 100 includes a gas turbine 110, a generator 130, a heat recovery boiler 140, a steam turbine 120, a fuel preheater 150, a high pressure water supply pipe 153, a water delivery pipe 155, A water supply temperature control pipe 154, a water supply pressure control pipe 158, a downstream control valve 161, and an intermediate control valve 162 may be included.

The gas turbine 110 according to this embodiment takes atmospheric air, compresses it to a high pressure, burns fuel in a constant pressure environment to release thermal energy, expands the high-temperature combustion gas, converts it into kinetic energy, and then converts the remaining energy into kinetic energy. The exhaust gas containing the can be released into the atmosphere.

The gas turbine 110 may include a compressor 112 , a combustor 115 , and a main turbine 113 . The compressor 112 of the gas turbine 110 may intake and compress air from the outside. The compressor 112 may supply compressed air compressed by the compressor blades to the combustor 115 and may also supply cooling air to a high-temperature region in the gas turbine 110 requiring cooling. At this time, since the sucked air undergoes an adiabatic compression process in the compressor 112, the pressure and temperature of the air passing through the compressor 112 increase.

The compressor 112 is designed as centrifugal compressors or axial compressors. A centrifugal compressor is applied in a small gas turbine, whereas a multi-stage axial compressor is applied in the same large gas turbine 110.

Meanwhile, the combustor 115 may mix compressed air supplied from the outlet of the compressor 112 with fuel and perform constant pressure combustion to produce high-energy combustion gas.

The high-temperature, high-pressure combustion gas produced by the combustor 115 is supplied to the main turbine 113 . In the main turbine 113, the thermal energy of the combustion gas is converted into mechanical energy by which the rotation shaft rotates by colliding and giving a reaction force to a plurality of blades arranged radially on the rotation shaft of the main turbine 113 while the combustion gas expands adiabatically. Part of the mechanical energy obtained from the main turbine 113 is supplied as energy required to compress air in the compressor 112, and the rest is used as effective energy such as generating electric power by driving the generator 130.

The combustion gas discharged from the main turbine 113 is cooled through the heat recovery boiler 140, purified, and discharged to the outside. The heat recovery boiler 140 not only cools the combustion gas, but also generates high-temperature and high-pressure steam by using the heat of the combustion gas, and transfers it to the steam turbine 120.

Steam generated in the heat recovery boiler 140 is transferred to the steam turbine 120 through the steam supply line 181, and the feed water cooled in the steam turbine 120 passes through the turbine feed water recovery line 182 to the heat recovery boiler. forwarded to (140).

The steam turbine 120 rotates blades using the steam generated by the heat recovery boiler 140 and transmits rotational energy to the generator 130. The steam turbine 120 supplies cooled steam to the heat recovery boiler 140 again.

In the first embodiment, the main turbine 113 and the steam turbine 120 are illustrated as being connected to one generator 130, but the present invention is not limited thereto, and the steam turbine 120 and the main turbine 113 ) can be arranged in parallel and connected to different generators.

In the turbine feedwater recovery line 182, a condenser 121 for condensing steam, a condensate water storage tank 122 for storing the condensed feedwater, and a condensate pump 123 for supplying the condensate stored in the condensate water storage tank 122 to the heat recovery boiler are provided. can be installed

Steam moving inside the heat recovery boiler 140 may have two or three levels of pressure, and accordingly, the supply water is pressurized to two or three or more pressure levels. In this embodiment, it is exemplified that the heat recovery boiler 140 has three levels of pressure.

The heat recovery boiler 140 may include a low pressure part G1 having a relatively low pressure, a medium pressure part G2 having a medium pressure, and a high pressure part G3 having a relatively high pressure. The high-pressure part (G3) is disposed adjacent to the inlet side through which combustion gas is introduced and heated by high-temperature combustion gas, and the low-pressure part (G1) is disposed adjacent to the outlet side through which combustion gas is discharged and heated by low-temperature combustion gas. It can be.

Inside the heat recovery boiler 140, a condensate preheater 141, a low pressure evaporator 142, a medium pressure economizer 143, a medium pressure evaporator 144, a high pressure economizer 145, and a high pressure evaporator 146 are installed. In addition, superheaters (not shown) may be additionally installed on the upstream sides of the evaporators. Combustion gas discharged from the heat recovery boiler 140 may be discharged through a stack.

The low pressure unit G1 includes a condensate preheater 141, a low pressure evaporator 142, and a low pressure drum 147. The condensate stored in the condensate storage tank 122 is transferred to the condensate preheater 141 by the condensate pump 123, and the condensate preheater 141 heats the condensate through heat exchange with combustion gas. The feed water heated in the condensate preheater 141 is transferred to the deaerator 175 to remove gas from the condensed water.

Feed water is supplied from the deaerator 175 to the low pressure drum 147, and the low pressure evaporator 142 is connected to the low pressure drum 147 to heat the feed water stored in the low pressure drum 147 to convert it into steam, and then to the low pressure drum ( 147) and then sent to the superheater.

Meanwhile, the middle pressure unit G2 includes a middle pressure economizer 143, a middle pressure evaporator 144, and a middle pressure drum 148. Water supplied from the deaerator 175 is supplied to the intermediate pressure economizer 143 by the intermediate pressure pump 172, and the intermediate pressure economizer 143 heats the supplied water through heat exchange with combustion gas. The water heated in the intermediate pressure economizer 143 is supplied to the intermediate pressure drum 148, and the intermediate pressure evaporator 144 is connected to the intermediate pressure drum 148 to heat the water stored in the intermediate pressure drum 148 and convert it into steam. After water separation in the intermediate pressure drum 148, it may be transferred to a superheater.

The high-pressure unit G3 includes a high-pressure economizer 145, a high-pressure evaporator 146, and a high-pressure drum 149. Water supplied from the deaerator 175 is supplied to the high-pressure economizer 145 by the high-pressure pump 173, and the high-pressure economizer 145 heats the water through heat exchange with combustion gas. The water heated in the high-pressure economizer 145 is supplied to the high-pressure drum 149, and the high-pressure evaporator 146 is connected to the high-pressure drum 149 to heat the water stored in the high-pressure drum 149 and convert it into steam. After separation in the high-pressure drum, it can be sent to the superheater.

Steam stored in the low-pressure drum 147, the intermediate-pressure drum 148, and the high-pressure drum 149 may be supplied to the respective low-pressure, medium-pressure, and high-pressure steam turbines after being heated in the superheater.

The high-pressure water supply pipe 153 connects the high-pressure part G3 and the fuel preheater 150 to supply high-temperature, high-pressure water to the fuel preheater 150 . A high-pressure valve 176 may be installed on an upstream side of the high-pressure drum 149 to control a flow rate of water supplied to the high-pressure water supply pipe 153 . Meanwhile, the supply water temperature control pipe 154 connects the intermediate pressure part G2 and the fuel preheater 150 to supply the first medium pressure supply water to the fuel preheater 150, and the supply water pressure control pipe 158 connects the intermediate pressure part G2 ) and the fuel preheater 150 are connected to supply the second medium-pressure water supply to the fuel preheater 150. An intermediate pressure valve 177 may be installed on the upstream side of the intermediate pressure drum 148 to control the flow rate of the water supplied to the water supply pressure control pipe 158 . In addition, the water supply pressure control pipe 158 may be directly connected to the intermediate pressure drum 148, and in this case, a pressure relief valve may be installed in the water supply pressure control pipe 158. When the water supply pressure control pipe 158 is directly connected to the intermediate pressure drum 148, an excellent pressure drop effect can be obtained.

The fuel preheater 150 receives fuel from the fuel supply unit 117 through the fuel supply pipe 157, heats it, and supplies it to the combustor 115. Here, the fuel may be made of gas, but the present invention is not limited thereto.

The fuel preheater 150 includes a primary heating unit 151 that primarily heats fuel and a secondary heating unit 152 that secondarily heats the heated fuel. The primary heating unit 151 receives fuel from the fuel supply unit 117, heats the fuel through heat exchange with relatively low-temperature feed water, and then transfers it to the secondary heating unit 152, and the secondary heating unit 152 ) heats the fuel delivered from the primary heating unit 151 to a high temperature through heat exchange with high-pressure water supply.

The high-pressure water supply pipe 153 is connected to the secondary heating unit 152 to supply high-temperature water to the secondary heating unit 152 . The high-pressure water supply pipe 153 is connected between the high-pressure economizer 145 and the high-pressure drum 149 to supply water heated by the high-pressure economizer 145 to the secondary heating unit 152 . Here, the high-pressure water supply is made of liquid rather than steam, and the phase of the water supply in the fuel preheater 150 does not change and maintains a liquid state. When the feedwater phase is changed in the fuel preheater 150, vibration may occur due to a rapid change in pressure.

The water delivery pipe 155 transfers the water cooled by heat exchange with the fuel in the secondary heating unit 152 to the primary heating unit 151 . Meanwhile, a water supply temperature control pipe 154 and a water supply pressure control pipe 158 are connected to the water supply transmission pipe 155 to supply medium-pressure water to the water supply transmission pipe 155 .

The supply water temperature control pipe 154 is connected to a downstream side of the intermediate pressure pump 172 and supplies the first intermediate pressure supply water pressurized by the intermediate pressure pump 172 to the supply water delivery pipe 155 . A check valve for preventing reverse flow may be installed in the water supply temperature control pipe 154 . Since the supply water temperature control pipe 154 is connected between the intermediate pressure pump 172 and the intermediate pressure economizer 143, the temperature of the supply water supplied to the primary heating unit 151 by supplying unheated water from the intermediate pressure unit G2 can be easily adjusted to prevent overheating of the fuel.

The water supply pressure control pipe 158 is connected between the intermediate pressure economizer 143 and the intermediate pressure drum 148 to supply second intermediate pressure water to the water delivery pipe 155 . The second intermediate pressure feed water has a higher temperature than the first intermediate pressure feed water, and the second intermediate pressure feed water is the feed water supplied from the intermediate pressure pump 172 and pressurized by the intermediate pressure economizer 143 .

Water supplied to the water supply pressure control pipe 158 is movable in both directions, and the water supply pressure control pipe 158 controls the pressure of the water supply delivery pipe 155 to be the same as the pressure upstream of the medium pressure drum.

Accordingly, the water heated in the intermediate pressure economizer 143 can flow into the water delivery pipe 155 through the water supply pressure control pipe 158, and the water supply delivery pipe 155 through the water supply pressure control pipe 158. Water supply may be introduced into the downstream side of the intermediate pressure economizer 143 of the intermediate pressure unit G2.

On the other hand, the capacity of the primary heating unit 151 and the secondary heating unit 152 may be made the same, and accordingly, the water supply is delivered through the water supply temperature control tube 154 and the water supply pressure control tube 158 only when necessary. Water may be supplied to the pipe 155 . The water discharged from the secondary heating unit 152 and the water delivered from the water supply temperature control tube 154 and the water supply pressure control tube 158 are mixed and supplied to the primary heating unit 151 .

When the pressure of the water supply temperature control pipe 154, the water supply transmission pipe 155, and the water supply pressure control pipe 158 are connected at the connection part C1, the pressure of the water supply transmission pipe 155 is the same as the pressure of the water supply pressure control pipe 158. If the water supply cannot move from the water supply pressure control pipe 158 to the water delivery pipe 155, and the pressure of the water supply delivery pipe 155 is higher than the pressure of the water supply pressure control pipe 158, it moves through the water supply delivery pipe 155. The supply water to be supplied moves to the intermediate pressure unit through the supply water pressure control pipe 158, and the pressure of the supply water delivery pipe may be controlled to be the same as the pressure upstream of the intermediate pressure drum.

In this way, when the supply water temperature control pipe 154 is connected to the supply water delivery pipe 155, the temperature of the supply water delivery pipe can be controlled using the relatively low-temperature first intermediate pressure supply water, and the supply water pressure control pipe 158 transmits the supply water. When connected to the pipe 155, it is possible to prevent the primary heating unit 151 and the secondary heating unit 152 from being damaged due to an excessive increase in pressure of the water delivery pipe.

On the other hand, the water supply recovery pipe 159 is connected to the primary heating unit 151, and the water recovery pipe 159 is connected to the downstream side of the condensate pump 123 to heat the fuel in the primary heating unit 151. The discharged feed water is delivered to the heat recovery boiler 140.

A pressure gauge (P1) for measuring the pressure of the feed water moving through the feed water delivery pipe 155 is installed in the feed water delivery pipe 155, and the secondary heating unit 152 downstream of the fuel supply pipe 157 has a second A thermometer T1 for measuring the temperature of the fuel discharged from the heating unit 152 is installed.

In addition, a downstream control valve 161 for controlling the flow rate of the water supply discharged from the primary heating unit 151 is installed in the water supply recovery pipe 159 . The downstream control valve 161 controls the flow rates of water supplied from the water supply temperature control pipe 154, water supplied from the water supply pressure control pipe 158, and water flowing through the water supply transmission pipe 155. When the opening of the downstream control valve 161 decreases, the pressure in the water delivery pipe 155 rises, and the surplus high-pressure water discharged from the secondary heating unit 152 passes through the water supply pressure control pipe 158 to the medium pressure drum. (148).

An intermediate control valve 162 is installed in the feed water delivery pipe 155 , and the intermediate control valve 162 controls the flow rate of the high-pressure feed water flowing into the secondary heating unit 152 . The intermediate control valve 162 is located between the secondary heating unit 152 and the connection part C1 to which the supply water temperature control pipe 154 and the supply water delivery pipe 155 are connected.

Accordingly, when the opening of the downstream control valve 161 decreases and the opening of the intermediate control valve 162 remains increased, the amount of feed water moving through the secondary heating unit 152 increases, and the primary heating The flow rate of feed water moving through the unit 151 may decrease. When the opening degree of the downstream control valve 161 decreases, if the high-pressure water supply cannot move through the water supply pressure control pipe 158, the flow accumulates and the pressure increases, and the increased pressure causes the primary heating unit 151 ) and the secondary heating unit 152 may be damaged.

On the other hand, when the opening of the downstream control valve 161 increases, the medium-pressure water supplied through the water supply temperature control pipe 154 and the water supply pressure control pipe 158 together with the high-pressure water discharged from the secondary heating unit 152 Water may be supplied to the primary heating unit 151 through the water delivery pipe 155 .

In addition, when the opening of the intermediate control valve 162 decreases, the flow rate of the water supply discharged from the secondary heating unit 152 decreases, so that the water supply temperature control pipe 154 and the water pressure control pipe 158 supply water transmission pipe ( 155) increases the flow rate of the medium pressure feedwater.

When the opening of the intermediate control valve 162 increases, the flow rate of the water supply discharged from the secondary heating unit 152 increases, so that the water supply temperature control pipe 154 and the water pressure control pipe 158 transfer the water supply pipe 155. The flow rate of the medium-pressure feed water flowing into the

As described above, according to the first embodiment, the water heated in the high-pressure economizer 145 is transferred to the secondary heating unit 152 through the high-pressure water supply pipe 153 so that the fuel can be heated to a high temperature and the water supply The temperature control pipe 154 is installed between the intermediate pressure pump 172 and the intermediate pressure economizer 143 to easily adjust the temperature of the feed water flowing into the primary heating unit 151 . In addition, the water supply pressure control pipe 158 is installed between the intermediate pressure economizer 143 and the intermediate pressure drum 148 to easily control the pressure of the water supply delivery pipe 155 within a preset range.

Hereinafter, a method for driving the combined power generation system according to the first embodiment of the present invention will be described. 4 is a flowchart illustrating a method of driving a combined power generation system according to a first embodiment of the present invention.

Referring to FIGS. 3 and 4, the driving method of the combined power generation system according to the present embodiment includes a fuel preheating step (S101), a water supply pressure determination step (S102), a fuel temperature determination step (S103), and a water supply pressure control step. (S104) and a fuel temperature control step (S105).

In the fuel preheating step (S101), the supply water heated in the high pressure part G3 is supplied to the secondary heating part 152, and the water supply discharged from the secondary heating part 152 and the first medium pressure supplied from the medium pressure part G2 are supplied. The feed water and the second intermediate pressure feed water having a higher temperature than the first intermediate pressure feed water are mixed and supplied to the primary heating unit 151 .

In the fuel preheating step (S101), water is supplied to the secondary heating unit 152 through the high-pressure water supply pipe 153 connected between the high-pressure economizer 145 and the high-pressure drum 149 in the high-pressure unit G3. In addition, in the fuel preheating step (S101), the water discharged from the secondary heating unit 152 is supplied to the primary heating unit 151 through the water supply pipe 155, and the intermediate pressure pump 172 and the intermediate pressure economizer ( 143) is connected to the water delivery pipe 155 to supply the first intermediate pressure water supply to the water delivery pipe 155, and between the intermediate pressure economizer 143 and the intermediate pressure drum 148 The second medium-pressure water supplied through the water supply pressure control pipe 158 connected to the water supply pipe 155 is supplied.

In the water supply pressure determination step (S102), the pressure of the water supply moving through the water supply delivery pipe 155 is compared with a preset reference pressure. In the water supply pressure determination step (S102), the pressure of the water supply is measured using the connection part C1 or the pressure gauge P1 installed on the downstream side of the connection part.

In the fuel temperature determination step (S103), the temperature of the fuel discharged from the secondary heating unit 152 is measured and compared with a preset reference temperature. In the fuel temperature determination step (S102), the temperature of the fuel is measured using a thermometer T1 installed downstream of the secondary heating unit 152.

In the supply water pressure control step (S104), the supply water pressure is controlled using the downstream control valve 161 that controls the flow rate of the supply water discharged from the primary heating unit. In the water supply pressure control step (S104), when the pressure of the water supply moving from the secondary heating unit 152 to the primary heating unit 151 is lower than a preset reference pressure, the opening of the downstream control valve 161 is reduced, When the pressure of the water supply moving from the secondary heating unit 152 to the primary heating unit 151 is higher than the preset reference pressure, the opening degree of the downstream control valve 161 is increased.

In addition, when the opening of the downstream control valve 161 is reduced in the water supply pressure control step (S104), some of the water discharged from the secondary heating unit 152 passes through the water supply pressure control pipe 158 to the middle pressure unit ( G2), and when the opening degree of the downstream control valve 161 is increased in the water supply pressure control step (S104), the second medium pressure water supply moves to the water supply delivery pipe 155 through the water supply pressure control pipe 158. can

In the fuel temperature control step (S105), the temperature of the fuel is adjusted by adjusting the intermediate control valve 162 for controlling the movement of feed water between the primary heating unit 151 and the secondary heating unit 152.

The fuel temperature control step (S105) increases the opening of the intermediate control valve 162 when the temperature of the fuel discharged from the secondary heating unit 152 is lower than the preset second reference temperature, and the secondary heating unit 152 When the temperature of the fuel discharged from ) is higher than the second reference temperature, the opening degree of the intermediate control valve 162 is reduced.

As described above, according to the first embodiment, the pressure of the water supply can be easily controlled by the water supply pressure control step (S104) and the fuel temperature control step (S105), and the fuel can be efficiently preheated while preventing the fuel from overheating. can

Hereinafter, a combined power generation system according to a second embodiment of the present invention will be described. 5 is a configuration diagram showing a fuel preheater according to a second embodiment of the present invention.

Referring to FIG. 5, the combined power generation system according to the second embodiment has the same structure as the combined power generation system according to the first embodiment except for the bypass pipe 156. Redundant descriptions are omitted.

A bypass pipe 156 bypassing the primary heating unit 151 and the secondary heating unit 152 and supplying fuel to the downstream side of the secondary heating unit 152 is connected to the fuel supply pipe 157 . In addition, a fuel control valve 163 for controlling the flow rate of fuel moving through the bypass pipe 156 is installed in the bypass pipe 156 .

The bypass pipe 156 controls the flow rate of the fuel passing through the primary heating unit 151 and the secondary heating unit 152, so that the heating temperature of the fuel can be more easily controlled.

Hereinafter, a method for driving a combined power generation system according to a second embodiment of the present invention will be described.

Since the driving method of the combined power generation system according to the second embodiment is the same as the driving method of the combined power generation system according to the second embodiment except for the step of controlling the fuel temperature, redundant description of the same components will be omitted.

The fuel temperature control step is an intermediate control valve 162 for controlling the movement of feed water between the primary heating unit 151 and the secondary heating unit 152, the primary heating unit 151 and the secondary heating unit 152 The temperature of the fuel is controlled by adjusting the fuel control valve 163 installed in the bypass pipe 156 for supplying fuel to the downstream side of the secondary heating unit 152 without going through.

In the fuel temperature control step, the opening of the fuel control valve 163 is reduced when the temperature of the fuel discharged from the secondary heating unit 152 is lower than a preset reference temperature, and when the fuel control valve 163 is closed, the intermediate control is performed. The degree of opening of the valve 162 is increased.

In addition, the fuel temperature control step increases the opening of the fuel control valve 163 when the temperature of the fuel discharged from the secondary heating unit 152 is higher than the second reference temperature, and when the fuel control valve 163 is fully opened. The opening degree of the intermediate control valve 162 is reduced.

When the opening of the fuel control valve 163 is reduced, the amount of bypassed fuel decreases, so the temperature of the fuel rises. As the flow rate increases, the temperature of the fuel may rise.

On the other hand, when the opening of the fuel control valve 163 is increased, the amount of bypassed fuel increases, so the temperature of the fuel decreases, and when the opening of the intermediate control valve 162 decreases, the secondary heating unit 152 The temperature of the fuel may decrease due to the decrease in the flow rate of the inflowing feedwater.

When the bypass pipe 156 and the fuel control valve 163 are installed as in the second embodiment, overheating of the fuel can be effectively prevented while minimizing the amount of feed water used for preheating the fuel.

Hereinafter, a combined power generation system according to a third embodiment of the present invention will be described. 6 is a configuration diagram showing a fuel preheater according to a third embodiment of the present invention.

Referring to FIG. 6 , the combined power generation system according to the third embodiment has the same structure as the combined power generation system according to the second embodiment except for the intermediate pressure control valve 165. Redundant descriptions are omitted.

An intermediate pressure control valve 165 is installed in the supply water temperature control pipe 154 to control the flow rate of the supply water supplied from the supply water temperature control pipe 154 to the supply water delivery pipe 155. The medium pressure control valve 165 not only prevents the reverse flow of the water supply, but also controls the inflow amount of the low-temperature water supply supplied through the water supply temperature control pipe 154. Accordingly, the temperature of the water supplied to the primary heating unit 151 through the water supply temperature control pipe 154 can be more easily adjusted.

On the other hand, a bypass pipe 156 for supplying fuel to the downstream side of the secondary heating unit 152 without passing through the primary heating unit 151 and the secondary heating unit 152 is connected to the fuel supply pipe 157. . In addition, a fuel control valve 163 for controlling the flow rate of fuel moving through the bypass pipe 156 is installed in the bypass pipe 156 .

Hereinafter, a method for driving a combined power generation system according to a third embodiment of the present invention will be described.

Since the driving method of the combined power generation system according to the third embodiment is the same as the driving method of the combined power generation system according to the third embodiment except for the step of controlling the fuel temperature, redundant description of the same components will be omitted.

In the fuel temperature control step, the temperature of the fuel is adjusted by adjusting the intermediate control valve 162, the fuel control valve 163, and the intermediate pressure control valve 165. In the fuel temperature control step, when the temperature of the fuel discharged from the secondary heating unit 152 is lower than a preset reference temperature, the opening degree of the intermediate pressure control valve 165 is reduced and the opening degree of the fuel control valve 163 is increased. decrease, and when the fuel control valve 163 is closed, the opening degree of the intermediate control valve 162 is increased.

Also, in the fuel temperature control step, when the temperature of the fuel discharged from the secondary heating unit 152 is higher than the second reference temperature, the opening of the intermediate pressure control valve 165 is increased, and the opening of the fuel control valve 163 is increased. is increased, and when the fuel control valve 163 is fully opened, the opening degree of the intermediate control valve 162 is decreased.

When the medium pressure control valve 165 is installed as in the third embodiment, the flow rate of the medium pressure water supply flowing into the water supply pipe 155 through the water supply temperature control pipe 154 is controlled to efficiently control the heating temperature of the fuel can do.

Although one embodiment of the present invention has been described above, those skilled in the art can add, change, delete, or add components within the scope not departing from the spirit of the present invention described in the claims. The present invention can be variously modified and changed by the like, and this will also be said to be included within the scope of the present invention.

100: combined power generation system 110: gas turbine
112: compressor 115: combustor
113: main turbine 120: steam turbine
121: condenser 122: condensate storage tank
123: condensate pump 130: generator
140: heat recovery boiler 141: condensate preheater
142: low pressure evaporator 143: medium pressure economizer
144: medium pressure evaporator 145: high pressure economizer
146: high pressure evaporator 147: low pressure drum
148: medium pressure drum 149: high pressure drum
150: fuel preheater 151: primary heating unit
152: secondary heating unit 153: high-pressure water supply pipe
154: water supply temperature control pipe 155: water supply delivery pipe
156, 166: bypass pipe 158: water supply pressure control pipe
159: water return pipe 161: downstream control valve
162: intermediate control valve 163, 167: fuel control valve
165: medium pressure control valve 172: medium pressure pump
173: high-pressure pump 175: deaerator
176: high pressure valve 181: steam supply line
182: turbine feed water recovery line

Claims (13)

A gas turbine generating rotational force by burning fuel;
a waste heat recovery boiler which heats feedwater using combustion gas discharged from the gas turbine and has a high pressure part, a medium pressure part, and a low pressure part having different pressure levels;
a fuel preheater which heats the fuel supplied to the gas turbine and has a primary heating unit and a secondary heating unit;
a high-pressure water supply pipe connected to the heat recovery boiler to supply water to the secondary heating unit;
a water delivery pipe connecting the secondary heating unit and the primary heating unit to supply water discharged from the secondary heating unit to the primary heating unit;
a feedwater temperature control pipe connected to the heat recovery boiler to supply first feedwater to the feedwater transmission pipe;
a feed water pressure control pipe connected to the heat recovery boiler to supply water to the feed water delivery pipe and supplying second feed water having a higher temperature than the first feed water;
Including,
A connection part is formed in the water supply delivery pipe to which the water supply temperature control pipe, the water supply delivery pipe, and the water supply pressure control pipe are connected.
An intermediate control valve is installed between the primary heating unit and the secondary heating unit to control the flow rate of high-pressure feedwater flowing into the secondary heating unit,
The intermediate control valve is located between the connection part and the secondary heating part. According to claim 1,
The high-pressure unit includes a high-pressure economizer for heating feed water, a high-pressure drum for storing the feed water heated by the high-pressure economizer, and a high-pressure evaporator for heating water in the high-pressure drum and converting it into steam,
The high-pressure water supply pipe is connected between the high-pressure economizer and the high-pressure drum to receive water heated by the high-pressure economizer. According to claim 1,
A combined power generation system further comprising a feed water recovery pipe for transferring the feed water discharged from the primary heating unit to a heat recovery boiler and a downstream control valve installed in the feed water recovery pipe to control the flow rate of the feed water discharged from the primary heating unit. . According to claim 3,
The intermediate pressure unit includes an intermediate pressure pump that pressurizes and moves the water supply, a medium pressure economizer that receives water from the intermediate pressure pump and heats the water supply, and an intermediate pressure drum that stores the water heated by the intermediate pressure economizer,
A combined power generation system in which surplus high-pressure feed water discharged from the primary heating unit is supplied to the intermediate-pressure drum through the feed water pressure control pipe by the downstream control valve. According to claim 1,
A bypass pipe connecting the upstream of the primary heating unit and the downstream of the secondary heating unit to bypass the primary heating unit and the secondary heating unit and move fuel to the downstream side of the secondary heating unit and the bypass pipe Combined power generation system further comprising a fuel control valve for controlling the flow rate of fuel moving through. According to claim 1,
By connecting upstream of the primary heating unit and upstream of the secondary heating unit, a bypass pipe bypassing the primary heating unit and moving fuel to the secondary heating unit controls the flow rate of the fuel moving through the bypass tube. A combined power generation system further comprising a fuel control valve for According to claim 1,
A combined power generation system in which an intermediate pressure control valve is installed in the feed water temperature control pipe to adjust the flow rate of feed water supplied from the feed water temperature control pipe to the feed water delivery pipe. A gas turbine, a steam turbine, a heat recovery boiler, a fuel preheater having a primary heating unit and a secondary heating unit for preheating fuel, and a water delivery pipe for supplying water discharged from the secondary heating unit to the primary heating unit, , In the method of driving a combined power generation system in which the heat recovery boiler includes a low pressure part, a medium pressure part, and a high pressure part,
The feedwater heated by the heat recovery boiler is supplied to the secondary heating unit, and the feedwater discharged from the secondary heating unit and the first feedwater supplied from the heat recovery boiler and the second feedwater having a higher temperature than the first feedwater A fuel preheating step of mixing feed water and supplying it to the primary heating unit;
Water supply pressure determination step of measuring the pressure of the water supply between the primary heating unit and the secondary heating unit;
A fuel temperature determination step of measuring the temperature of the fuel discharged from the secondary heating unit and comparing it with a reference temperature;
a water supply pressure control step of controlling the pressure of the water supply using a downstream control valve that controls the flow rate of the water supply discharged from the primary heating unit;
A fuel temperature control step of controlling the temperature of the fuel by adjusting an intermediate control valve that controls the movement of feed water between the primary heating unit and the secondary heating unit;
Including,
In the fuel preheating step, the water supply discharged from the secondary heating unit, the first water supply, and the second water supply are joined at a connection part formed in the water supply delivery pipe,
The intermediate control valve is a method of driving a combined power generation system located between the connection part and the secondary heating part. According to claim 8,
The fuel preheating step is a method of driving a combined power generation system in which water is supplied to the secondary heating unit through a high-pressure water supply pipe connected between the high-pressure economizer and the high-pressure drum of the high-pressure unit. According to claim 8,
In the water supply pressure control step, when the pressure of the water supply moving from the secondary heating unit to the primary heating unit is lower than a preset reference pressure, the opening of the downstream control valve is reduced, and the secondary heating unit controls the primary heating unit. A method of driving a combined power generation system in which the opening of the downstream control valve is increased when the pressure of the feedwater moving to the heating unit is higher than a preset reference pressure. According to claim 10,
When the opening of the downstream control valve is reduced in the water supply pressure control step, some of the water supplied from the secondary heating unit is discharged,
It moves to the middle pressure part through a feed water pressure control pipe connecting the heat recovery boiler and the feed water delivery pipe,
In the supply water pressure control step, when the opening of the downstream control valve is increased, the second water supply is moved to the water supply delivery pipe through the water supply pressure control pipe. According to claim 8,
The fuel temperature control step increases the opening of the intermediate control valve when the temperature of the fuel discharged from the secondary heating unit is lower than the preset reference temperature, and the temperature of the fuel discharged from the secondary heating unit is lower than the preset reference temperature. A method of driving a combined power generation system in which the opening degree of the intermediate control valve is reduced when it is higher than the second reference temperature. According to claim 8,
The fuel temperature control step bypasses the primary heating unit and the secondary heating unit and adjusts the temperature of the fuel by adjusting a fuel control valve installed in a bypass pipe for supplying fuel to the downstream side of the secondary heating unit,
When the temperature of the fuel discharged from the secondary heating unit is lower than the preset second reference temperature, the opening of the fuel control valve is reduced, and when the fuel control valve is closed, the opening of the intermediate control valve is increased. ,
A combination of increasing the opening of the fuel control valve when the temperature of the fuel discharged from the secondary heating unit is higher than the second reference temperature and decreasing the opening of the intermediate control valve when the fuel control valve is fully opened. How to drive a power generation system.

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