JPH0874516A - Method for controlling feeding water and method for controlling gas for exhaust gas after burning-type combined cycle - Google Patents

Abstract

PURPOSE: To prevent boiler efficiency and plant efficiency from being deteriorated caused by performance deviation of a gas turbine exhaust gas cooler by controlling the high-pressure feed water superheater feed water flow rate or the high-pressure gas feed water heater feed water flow rate, so that the gas turbine exhaust gas cooler outlet gas temperature may become the set value or less. CONSTITUTION: Condensed water is boosted by a boiler feed water pump 9, heated by extracted steam of a steam turbine 4 by a high-pressure feed water heater 8, further heated by a high-pressure feed water heater 13 provided in parallel with the high- pressure feed water heater 8, and fed to a boiler 3. The feed water distribution to a high-pressure feed water heater inlet feed water flow rate adjusting valve 41 and a high-pressure gas feed water heater inlet feed water flow rate adjusting valve 42 is controlled by a flow rate controller 35, so that the gas temperature to be measured by a gas turbine exhaust gas cooler outlet gas thermometer 31 may be made into the constant value. Thereby the boiler inlet gas temperature is made constant without being affected by performance deviation of a gas turbine exhaust gas cooler 12, and boiler efficiency and plant efficiency are also stabilized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water supply control method and a gas control method for an exhaust gas reburn type combined cycle.

[0002]

2. Description of the Related Art As one of the methods of an exhaust gas re-combustion combined cycle, when the heat resistant temperature of the boiler inlet is lower than the temperature of the high temperature gas turbine exhaust gas, the gas turbine exhaust gas cooler reduces the gas turbine exhaust gas to the temperature lower than the boiler inlet heat resistant temperature. There is an exhaust gas re-combustion combined cycle feed water heater system that lowers and uses the gas turbine exhaust gas as boiler combustion air. Exhaust gas refueling type combined cycle feed water heater system is a gas turbine exhaust gas cooler that cools the gas turbine exhaust gas and heats the feed water that is sent to the boiler, and a high pressure gas feed water heater that heats the feed water. There is a gas side water supply system consisting of the above, and an extraction side water supply system consisting of a high pressure water supply heater that heats the water supply by steam turbine extraction air that is installed in parallel with the gas side water supply system.

In the conventional exhaust gas re-combustion combined cycle, the feed water flow rate distribution between the gas side feed water system and the extraction side feed water system is such that the high pressure feed water heater outlet feed water temperature and the gas turbine exhaust gas cooler outlet feed water temperature are equalized and joined. It is controlled to supply water to.

[0004]

In the conventional method of controlling the water supply system in the exhaust gas re-combustion combined cycle, the boiler inlet gas temperature changes due to the performance deviation of the gas turbine exhaust gas cooler, which affects the boiler efficiency and the plant efficiency.
When the performance of the gas turbine exhaust gas cooler is good, there is a problem that the gas temperature of the gas turbine exhaust gas cooler outlet (boiler inlet gas temperature) decreases, and the boiler efficiency and plant efficiency decrease. An object of the present invention is to provide a water supply control method and a gas control method that prevent a decrease in boiler efficiency and plant efficiency due to performance deviation of a gas turbine exhaust gas cooler.

[0005]

In order to solve the above-mentioned problems, the present invention provides a gas turbine exhaust gas cooler outlet gas thermometer for measuring a gas temperature on the gas turbine exhaust gas cooler outlet side, and a gas turbine exhaust gas cooler outlet is provided. The high-pressure feed water heater feed flow rate or the high-pressure gas feed water heater feed water flow rate is controlled so that the temperature measured by the gas thermometer becomes a set value, and it is considered that the heat recovery amount of the gas turbine exhaust gas cooler does not increase from the plan. For distribution of feed water flow rate, high pressure feed water heater feed water flow rate control valve for controlling feed water flow rate, high pressure gas feed water heater feed water flow rate control valve for controlling feed water flow rate, or both May be installed.

In another method of the present invention, in order to solve the above-mentioned problems, a gas turbine exhaust gas cooler outlet feed water thermometer for measuring the feed water temperature at the gas turbine exhaust gas cooler outlet side and a gas at the high pressure feed water heater outlet side are provided. Install a high-pressure feed water heater outlet feed water temperature meter that measures the feed water temperature before joining with the turbine exhaust gas cooler outlet feed water, and supply water temperature measured by the gas turbine exhaust gas cooler outlet feed water temperature meter and high-pressure water heater outlet feed water temperature meter The temperature of the water supplied to the gas turbine exhaust gas cooler is controlled to be within the set temperature difference, and the temperature of the gas turbine exhaust gas cooler outlet is higher than or equal to the outlet pressure of the high pressure water heater. Consideration is given so that the amount of recovered heat does not exceed the plan. For distribution of feed water flow rate, high pressure feed water heater feed water flow rate control valve for controlling feed water flow rate, high pressure gas feed water heater feed water flow rate control valve for controlling feed water flow rate, or both May be installed.

In another method of the present invention, in order to solve the above-mentioned problems, the gas turbine exhaust gas cooler outlet gas thermometer and a feed pipe between a plurality of high pressure feed water heaters or a high pressure feed water heater outlet side. Installed in the gas turbine exhaust gas cooler outlet water supply pipe or the gas turbine exhaust gas cooler outlet water bypass pipe that connects the gas turbine exhaust gas cooler outlet water supply pipe to the high pressure gas feed water heater outlet side water supply pipe. By controlling the gas turbine exhaust gas cooler bypass feed water flow rate or the gas turbine exhaust gas cooler feed water flow rate so that the temperature becomes the set value, it is considered that the heat recovery amount of the gas turbine exhaust gas cooler does not increase from the plan. For distribution of the feed water flow rate, a gas turbine exhaust gas cooler bypass feed water flow rate control valve that controls the gas turbine exhaust gas cooler bypass feed water flow rate, a gas turbine exhaust gas cooler feed water flow rate control valve that controls the gas turbine exhaust gas cooler feed water flow rate, or both May be installed.

In another method of the present invention, in order to solve the above-mentioned problems, a gas turbine exhaust gas cooler gas bypass system for bypassing the gas turbine exhaust gas cooler and a gas turbine exhaust gas for gas bypassing the gas turbine exhaust gas cooler are used. A boiler inlet gas thermometer that measures the gas temperature after joining the gas that has passed through the cooler is installed, and the bypass distribution is controlled so that the gas temperature measured by the gas thermometer reaches the set temperature, and the gas turbine The amount of heat recovered from the exhaust gas cooler is taken into consideration so as not to exceed the planned amount.

[0009]

With the above means, it is possible to prevent the boiler efficiency and the plant efficiency from decreasing due to the performance deviation of the gas turbine exhaust gas cooler by keeping the boiler inlet gas temperature high below the boiler inlet heat resistant temperature.

[0010]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 shows a first embodiment of the present invention. The rotational energy of the gas turbine 1 becomes an electric output in the generator 2, and the exhaust gas of the gas turbine 1 enters the gas turbine exhaust gas cooler 12 and is cooled and used as combustion air for the boiler 3. The steam turbine 4 is driven by the steam generated in the boiler 3, and the generator 5 produces an electric output. The steam that has worked in the steam turbine 4 is condensed in the condenser 6 and the steam turbine 4
Condensate is heated by the low-pressure feed water heater 11 by the extraction of
The low pressure gas feed water heater 14 provided in parallel with the low pressure feed water heater 11 heats the condensate with the boiler exhaust gas, and the deaerator 1
At 0, the condensate is degassed, the pressure of the condensate is boosted by the boiler feedwater pump 9, and the condensate is further heated by the high-pressure feedwater heater 8 that heats the condensate by the extraction of the turbine, and the condensate is paralleled The condensate is further heated by the high-pressure gas feed water heater 13 provided in, and is sent to the boiler. Here, the high-pressure feed water heater inlet feed water flow rate control valve 41 and the high-pressure gas feed water inlet feed water flow rate are adjusted by the flow rate control device 35 so that the gas temperature measured by the gas turbine exhaust gas cooler outlet gas thermometer 31 becomes constant. By controlling the water supply distribution of the valve 42, the boiler inlet gas temperature becomes constant regardless of the performance deviation of the gas turbine exhaust gas cooler 12, and the boiler efficiency and plant efficiency are also stabilized.

FIG. 2 shows a second embodiment of the present invention. The water and gas system is the same as that of the first embodiment, but the distribution control of the condensate to the gas side system and the extraction side system is performed by the feed water temperature measured by the gas turbine exhaust gas cooler outlet feed water temperature meter 32 and the high pressure. Flow rate control such that the temperature difference of the feed water temperature measured by the feed water heater outlet feed water temperature meter 33 is set, and the gas turbine exhaust gas cooler outlet feed water temperature rises in the range of about 0 ° C to 50 ° C or less. By controlling the water supply distribution of the high-pressure feed water heater inlet feed water flow rate control valve 41 and the high-pressure gas feed water heater inlet feed water flow rate control valve 42 by the device 36, the water flow rate to the gas side water supply system is reduced and the boiler inlet gas The temperature can be raised, and the boiler efficiency and plant efficiency can be raised.

FIG. 3 shows a third embodiment of the present invention. In addition to the first embodiment, the water and gas system is provided with a gas turbine exhaust gas cooler feed water bypass pipe 21 that connects the outlet of the high pressure gas feed water heater and the high pressure feed water heater. The feed water distribution of the high pressure feed water heater inlet feed water flow rate control valve 41 and the high pressure gas feed water heater inlet feed water flow rate control valve 42 is a constant valve opening, and the gas temperature measured by the gas turbine exhaust gas cooler outlet gas thermometer 31 is By controlling the feed water distribution of the feed water bypass control valve 44 and the gas turbine exhaust gas cooler feed water flow control valve 43 by the flow control device 37 so as to be constant, the boiler inlet gas temperature does not depend on the performance deviation of the gas turbine exhaust gas cooler 12. Is constant, and boiler efficiency and plant efficiency are stable.

FIG. 4 shows a fourth embodiment of the present invention. In addition to the water and gas system of the first embodiment, a gas turbine exhaust gas cooler gas bypass system 22 for bypassing the gas turbine exhaust gas cooler 12 is provided, a high pressure feed water heater inlet feed water flow rate control valve 41 and the high pressure gas feed water heating. The water supply distribution of the equipment inlet water supply flow rate control valve 42 is made to be a constant valve opening degree, and the gas damper 45 is controlled by the flow rate control device 38 so that the gas temperature measured by the boiler inlet gas thermometer 34 becomes constant, and the gas bypass amount. By controlling the above, the boiler inlet gas temperature becomes constant regardless of the performance deviation of the gas turbine exhaust gas cooler 12, and the boiler efficiency and the plant efficiency are stabilized.

[0015]

According to the present invention, by keeping the boiler inlet gas temperature high below the boiler inlet heat resistant temperature, it is possible to prevent the boiler efficiency and the plant efficiency from being lowered due to the performance deviation of the gas turbine exhaust gas cooler. It will be possible.

[Brief description of drawings]

FIG. 1 is a schematic system configuration diagram in a first embodiment of the present invention.

FIG. 2 is a schematic system configuration diagram in a second embodiment of the present invention.

FIG. 3 is a schematic system configuration diagram in a third embodiment of the present invention.

FIG. 4 is a schematic system configuration diagram in a fourth embodiment of the present invention.

[Explanation of symbols]

1 ... Gas turbine, 2, 5 ... Generator, 3 ... Boiler, 4 ...
Steam turbine, 6 ... Condenser, 7 ... Chimney, 8 ... High pressure feed water heater, 9 ... Boiler feed pump, 10 ... Deaerator, 11 ... Low pressure feed water heater, 12 ... Gas turbine exhaust gas cooler, 13
… High-pressure gas feed water heater, 14… Low-pressure gas feed water heater, 2
1 ... Gas turbine exhaust gas cooler feed water bypass pipe, 22 ...
Gas turbine exhaust gas cooler gas bypass system.

Claims (4)

[Claims] 1. A gas turbine, a gas turbine exhaust gas cooler that cools the exhaust gas of the gas turbine and heats the feed water that is sent to the boiler, and a steam that uses the gas turbine exhaust gas cooled by the gas turbine exhaust gas cooler as combustion air. , A steam turbine driven by steam generated in the boiler, a condenser for condensing the steam working in the steam turbine, a low-pressure feed water heater for heating the condensate by steam turbine extraction, It is installed in parallel with the low-pressure feed water heater, which heats the condensate with boiler exhaust gas, which is installed in parallel with the low-pressure feed water heater, the high-pressure feed water heater which heats the condensate water by the steam turbine bleed air, and the high-pressure feed water heater. In an exhaust gas re-combustion combined cycle power plant consisting of a high pressure gas feed water heater that heats the condensate with the boiler exhaust gas A gas turbine exhaust gas cooler outlet gas thermometer for measuring the gas temperature is installed on the gas turbine exhaust gas cooler outlet side so that the temperature measured by the gas turbine exhaust gas cooler outlet gas thermometer is below a set value. A feed water control method for an exhaust gas re-combustion combined cycle, comprising controlling a feed water flow rate of a heater or a high pressure gas feed water. 2. The exhaust gas re-combustion combined cycle power plant according to claim 1, wherein the gas turbine exhaust gas cooler outlet feed water thermometer for measuring the feed water temperature at the gas turbine exhaust gas cooler outlet side and the gas turbine exhaust gas at the high pressure feed water heater outlet side. Install a high-pressure feed water heater outlet feed water temperature meter to measure the feed water temperature before joining with the cooler outlet feed water, and measure it with the feed water temperature measured by the gas turbine exhaust gas cooler outlet feed water temperature meter and the high pressure feed water heater outlet water temperature thermometer. A method for controlling water supply in an exhaust gas re-combustion combined cycle, characterized in that the difference between the supplied water temperature and the supplied water temperature is controlled to be within a set temperature difference. 3. The exhaust gas re-combustion combined cycle power plant according to claim 1, wherein the gas turbine exhaust gas cooler outlet gas thermometer and a plurality of high-pressure feed water heaters have a water supply pipe or a high-pressure water supply heater outlet side water supply. Install a gas turbine exhaust gas cooler outlet water supply bypass pipe connecting the gas turbine exhaust gas cooler outlet water supply pipe and the high pressure gas feed water heater outlet side water supply pipe, and check the gas temperature measured by the gas turbine exhaust gas cooler outlet gas thermometer. A feed water control method for an exhaust gas re-combustion combined cycle, comprising controlling a gas turbine exhaust gas cooler bypass feed water flow amount or a gas turbine exhaust gas cooler feed water flow amount so as to attain a set value. 4. The exhaust gas re-combustion combined cycle power plant according to claim 1, wherein a gas turbine exhaust gas cooler gas bypass system for bypassing the gas turbine exhaust gas cooler and a gas bypassing the gas turbine exhaust gas cooler form a gas turbine exhaust gas cooler. A boiler inlet gas thermometer for measuring the gas temperature after joining with the passing gas is installed, and bypass distribution is controlled so that the gas temperature measured by the boiler inlet gas thermometer becomes a set temperature. A gas control method for an exhaust gas re-combustion combined cycle, which is characterized.