JPH07133903A - Controller for feed water heater - Google Patents

Abstract

PURPOSE:To prevent collapse of thermal balance of a plant and to prevent steaming in a condensate tube by obtaining a distribution ratio of condensate flow rates of a steam heater system and a gas heater system from a load signal of a steam turbine, and controlling the flow rates by a regulating valve according to the ratio. CONSTITUTION:The feed water heater controller comprises a condensate system having a low-pressure feed water heater system for heating condensate by a low-pressure feed water heater 2 by bleed of a steam turbine and a gas heater system for heating condensate by a gas heater 3. A low-pressure feed water heater condensate flow regulating valve 4 and a gas heater condensate flow regulating valve 5 are opened during operating of a plant, condensates are fed to the steam heater system and the gas heater system, and condensate after combining is introduced to a deaerator 1. In this case, a load signal of the turbine is input to a condensate flow controller 7, which obtains a distribution ratio of the condensate flow rates of the respective systems. A condensate flow control to the heater 3 is conducted by the valve 5 through a controller 6 according to the obtained ratio.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a feedwater heater control device used in a repowering power plant or the like for introducing exhaust gas from a gas turbine into a boiler and reburning it, and particularly, it is installed in parallel with a low pressure feedwater heater. The present invention relates to a feed water heater control device for controlling a distribution ratio of a condensate flow rate flowing to a gas heater.

[0002]

2. Description of the Related Art A conventional thermal power plant has a means for controlling water flow to a gas heater system because the condensate flows only to a low-pressure feed water heater system that heats the condensate by steam extraction from a steam turbine. Didn't.

[0003]

Therefore, in the conventional power plant, the low-pressure feed water heater system heats the steam turbine bleed air, and the gas heater system heats the exhaust gas and the condensate of the boiler. Therefore, there was a problem that the difference in condensate temperature between the two systems occurred and the heat balance of the plant was lost. Further, when the high-temperature condensate of the gas heater system merges with the low-pressure condensate, steaming may occur in the pipe and damage the condensate pipe.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a feed water heater control device which prevents steaming of the condensate pipe at the outlet of the gas heater and loss of heat balance.

[0005]

In order to achieve the above object, the first aspect of the present invention is that the condensate is heated by the exhaust gas of a boiler by a low-pressure feed water heater system and a gas heater in which the condensate is heated by the steam extraction of the steam turbine. Has a condensate system consisting of a gas heater system to be heated, and branches into the low-pressure feed water heater system and the gas heater system at the inlet side of the condensate system, and joins at the outlet side of the condensate system. In the feedwater heater control device for heating and controlling the condensate system configured as described above, a control valve is installed in each of the low-pressure feedwater heater system and the gas heater system, and the control signal is provided according to the water level of the deaerator and the load signal of the steam turbine. It is characterized in that control means for distributing and controlling the amount of condensed water flowing through the low-pressure feed water heater system and the gas heater system is provided by the control valve.

According to a second aspect of the present invention, a control valve is installed in each of the low pressure feed water heater system and the gas heater system, and a limit temperature calculating means for calculating a limit temperature from the condensate pipe pressure at the outlet of the gas heater system, The limit temperature calculated by the limit temperature calculation means is compared with the condensate temperature at the gas heater system outlet to obtain the distribution ratio of the amount of condensate flowing through the low pressure feed water heater system and the gas heater system, and the control valve is opened / closed. It is characterized in that a control means for controlling is provided.

According to a third aspect of the present invention, a limiting temperature calculating means for installing a control valve in each of the low-pressure feed water heater system and the gas heater system, and calculating a limit temperature from the condensate pipe pressure at the outlet of the gas heater system, The limit temperature calculated by the limit temperature calculation means and the condensate temperature at the gas heater system outlet are compared to determine the distribution ratio of the condensate flow amount flowing to the low-pressure feed water heater system and the gas heater system, and via the closing side limit. Control means for controlling the opening and closing of the control valve provided in the gas heater system.

According to a fourth aspect of the present invention, the limit temperature calculating means for calculating the limit temperature from the water level of the deaerator, the limit temperature calculated by the limit temperature calculating means and the condensate temperature of the deaerator are used. It is characterized in that the distribution ratio of the amount of condensate flowing through the low-pressure feed water heater system and the gas heater system is obtained, and the closing of the control valve provided in the gas heater system is restricted via a closing side limit.

According to a fifth aspect of the present invention, a control valve is installed in each of the low pressure feed water heater system and the gas heater system, and the low pressure feed water heating is performed by the water level and temperature of the deaerator and the load signal of the steam turbine. Determined by the control means for distributing and controlling the amount of condensate flowing in the gas heater system and the gas heater system by the regulating valve, the limit temperature calculating means for calculating the limit temperature from the water level of the deaerator, and the limit temperature calculating means. The distribution ratio of the amount of condensate flowing through the low-pressure feedwater heater system and the gas heater system is obtained from the limit temperature and the condensate temperature of the deaerator, and the control valve of the control valve provided in the gas heater system is closed via a closed side limit. It is characterized in that the confinement is restricted.

[0010]

According to the present invention, the distribution ratio of condensate is obtained from the load signal of the steam turbine, and the control valve distributes and controls the condensate flow rates of the low-pressure feed water heating system and the gas heater system, thereby breaking the heat balance of the plant. It becomes possible to prevent it. In addition, in any case, the steam temperature inside the condensate pipe is controlled by determining the condensate temperature limit of the gas heater system outlet by the pressure and temperature of the condensate pipe or the pressure and temperature of the deaerator and controlling the opening of the control valve. Can be prevented.

[0011]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a system diagram of a feed water heater controller according to a first embodiment of the present invention. As shown in the figure, the steam turbine load is taken into the condensate flow control device 7, the opening of the gas heater condensate flow control valve 5 is adjusted via the controller 6, and the amount of condensate flowing through the gas heater 3 is controlled. On the other hand, the condensate flow rate flowing through the low pressure feed water heater 2 is controlled by the low pressure feed water heater condensate flow rate control valve 4 based on factors such as the water level of the deaerator 1. As a result, it is possible to distribute the condensate flow rate of both systems.

Next, the operation of this embodiment will be described.
When the plant is in operation, the low-pressure feed water heater condensate flow rate control valve 4 and the gas heater condensate flow rate control valve 5 are opened to allow condensate to flow to the steam heater system and the gas heater system. In the steam heater system, the low-pressure feed water heater 2 heats the condensate by extracting steam from the steam turbine, and in the gas heater system, the gas heater 3 heats the condensate by the exhaust gas from the boiler.

In the condensate heating process, the load signal of the steam turbine is taken into the condensate flow control device 7,
The distribution ratio of the condensate flow rates of both systems is obtained, and the condensate flow rate control of the gas heater is performed by the gas heater condensate flow rate control valve 5 via the controller 6. The combined condensate flows into the deaerator 1.

Therefore, in this embodiment, the load signal of the steam turbine is taken into the condensate flow rate control device 7 to obtain the distribution ratio of the condensate flow rate of each system, and the gas heater condensate flow rate control valve 5 is used via the controller 6. By controlling the condensate flow rate according to the distribution ratio, it is possible to prevent the heat balance of the plant from being disturbed and prevent steaming in the piping.

FIG. 2 is a system diagram of a feed water heater controller according to a second embodiment of the present invention. As shown in the figure, the pressure of the condensate pipe at the outlet of the gas heater system is measured by the pressure transmitter 9, and is taken into the limit temperature calculation device 8 to calculate the limit temperature. The distribution ratio is obtained by comparing the condensate temperatures at the gas heater system outlets measured in step 1, and the opening / closing of the gas heater condensate flow control valve 5 is controlled via the controller 6. On the other hand, the condensate flow rate flowing through the low pressure feed water heater 2 is controlled by the low pressure feed water heater condensate flow rate control valve 4 based on factors such as the water level of the deaerator 1. By such control, it becomes possible to adjust the condensate temperature of the gas heater system and prevent steaming in the condensate pipe.

FIG. 3 is a system diagram of a feed water heater controller according to a third embodiment of the present invention. As shown in the figure, during operation of the gas turbine, the pressure of the condensate pipe at the outlet of the gas heater system is measured by the pressure transmitter 9 and taken into the limit temperature calculation device 8 to calculate the limit temperature, and a value with a margin is set. , Temperature transmitter 1
The distribution ratio is obtained by comparing the condensate temperature at the gas heater system outlet measured at 0, and the steam turbine load signal is taken into the condensate flow control device 7. Then, the closing side limit 11 and the controller 6 limit the closing of the gas heater condensate flow control valve 5 using the calculation results of the limit temperature calculation device 8 and the condensate flow control device 7. On the other hand, low-pressure feed water heater 2
The condensate flow rate flowing through is controlled by the low-pressure feed water heater condensate flow rate control valve 4 based on factors such as the level of the deaerator 1. By performing such control, it is possible to maintain a constant flow rate even when a load change occurs in the steam turbine, and it is possible to prevent steaming in the condensate pipe.

FIG. 4 is a system diagram of a feed water heater controller according to a fourth embodiment of the present invention. The present embodiment is different from the second embodiment in that the second embodiment measures the pressure and temperature for calculating the limit temperature from the gas heater system.
In the present embodiment, this pressure and temperature are taken in from the deaerator 1 to control the condensate distribution between the steam heater system and the gas heater system. That is, the pressure of the condensate pipe at the outlet of the gas heater system is measured by the pressure transmitter 9, the temperature is taken into the limit temperature calculation device 8 to calculate the limit temperature, and a value with a margin for it and the gas heater measured by the temperature transmitter 10 are taken. The condensate temperature at the outlet of the system is compared to obtain the distribution ratio, and the opening / closing of the gas heater condensate flow control valve 5 is controlled via the controller 6. On the other hand, the condensate flow rate flowing through the low-pressure feed water heater 2 is
Control is performed by the low-pressure feed water condensate flow rate control valve 4 based on factors such as the level of the deaerator 1. With such control, the condensate temperature of the gas heater system can be adjusted, and steaming in the condensate pipe can be prevented.

FIG. 5 is a system diagram of a fifth embodiment of the present invention. The present embodiment differs from the third embodiment in that the pressure and temperature for calculating the limit temperature are measured from the gas heater system in the third embodiment, while the pressure and temperature are measured in the present embodiment. Is taken in from the deaerator 1 to perform condensate distribution control of the steam heater system and the gas heater system. That is, during operation of the gas turbine, the pressure of the condensate pipe and the temperature of the condensate at the outlet of the gas heater system are measured by the pressure transmitter 9 and the temperature transmitter 10, respectively, and the limit temperature calculator 8 calculates the limit temperature. Further, the steam turbine load signal is taken into the condensate flow control device 7. The closing side limit 11 and the controller 6 limit the closing of the gas heater condensate flow control valve 5 using the calculation results of the limit temperature calculation device 8 and the condensate flow control device 7. On the other hand, the condensate flow rate flowing through the low-pressure feed water heater 2 is controlled by the low-pressure feed water heater condensate flow rate control valve 4 based on factors such as the level of the deaerator 1. By performing such control, it is possible to maintain a constant flow rate even when a load change occurs in the steam turbine.

[0019]

As described above, according to the present invention,
By obtaining the distribution ratio of the condensate flow rate of each of the steam heater system and the gas heater system from the load signal of the steam turbine, and controlling the condensate flow rate by the control valve, it is possible to prevent the heat balance of the plant from being disturbed. Further, by setting the limit temperature of condensate inside the deaerator or at the outlet of the gas heater system and controlling the control valve based on this, steaming inside the condensate pipe can be prevented.

[Brief description of drawings]

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

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

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

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

FIG. 5 is a system diagram of a fifth embodiment of the present invention.

[Explanation of symbols]

1 ... Deaerator, 2 ... Low-pressure feed water heater, 3 ... Gas heater, 4
... Low-pressure feed water heater Condensate flow rate control valve, 5 ... Gas heater condensate flow rate control valve, 6 ... Controller, 7 ... Condensate flow rate control device, 8 ... Limit temperature calculation device, 9 ... Pressure transmitter, 10 ... Temperature transmitter , 11 ... Closed side limit.

Claims (5)

[Claims] 1. A condensate system comprising a low-pressure feed water heater system in which condensate is heated by extraction of steam from a steam turbine, and a gas heater system in which condensate is heated by exhaust gas from a boiler by a gas heater. In the feed water heater control device for heating and controlling the condensate system that is configured to branch to the low pressure feed water heater system and the gas heater system at the inlet side of and confluence at the outlet side of the condensate system, A control valve is installed in each of the feed water heater system and the gas heater system, and the control valve controls the amount of condensed water flowing through the low pressure feed water heater system and the gas heater system according to the water level of the deaerator and the load signal of the steam turbine. A feed water heater control device comprising control means for distribution control. 2. A limit temperature calculating means for calculating a limit temperature from the condensate pipe pressure at the outlet of the gas heater system, and a limit temperature calculating means by installing a control valve in each of the low-pressure feed water heater system and the gas heater system. A control means is provided for comparing the obtained limit temperature and the condensate temperature at the gas heater system outlet to obtain the distribution ratio of the condensate amount flowing to the low-pressure feed water heater system and the gas heater system, and controlling the opening / closing of the control valve. The feed water heater control device according to claim 1, wherein 3. A limit temperature calculation means for installing a control valve in each of the low-pressure feed water heater system and the gas heater system and calculating a limit temperature from the condensate pipe pressure at the outlet of the gas heater system, and the limit temperature calculation means. The distribution ratio of the amount of condensate flowing to the low-pressure feed water heater system and the gas heater system is calculated by comparing the obtained limit temperature with the condensate temperature at the gas heater system outlet, and the gas heater system is provided via the closed side limit. 2. The feed water heater control device according to claim 1, further comprising control means for controlling opening and closing of the control valve. 4. A limit temperature calculating means for calculating a limit temperature from the water level of the deaerator, and a low pressure feed water heater system based on the limit temperature calculated by the limit temperature calculating means and the condensate temperature of the deaerator. The feed water heater control according to claim 1, wherein the distribution ratio of the amount of condensate flowing through the gas heater system is obtained, and the closing of the control valve provided in the gas heater system is limited via a closing side limit. apparatus. 5. A control valve is installed in each of the low-pressure feed water heater system and the gas heater system, and the low-pressure feed water heater system and the gas heater system are controlled by the water level and temperature of the deaerator and the load signal of the steam turbine. Control means for distributing and controlling the amount of condensate flowing through the control valve, limit temperature calculation means for calculating a limit temperature from the water level of the deaerator, limit temperature calculated by the limit temperature calculation means and the degassing To determine the distribution ratio of the amount of condensate flowing through the low-pressure feed water heater system and the gas heater system from the condensate temperature of the reactor, and limit the closing of the control valve provided in the gas heater system via the closing side limit. The feed water heater control device according to claim 1.