JPH094414A - Supply water heating control device - Google Patents

Abstract

PURPOSE: To adopt a part of steam flowing through a low pressure turbine bypass valve to supply water heating in a steam turbine plant which has a system for supplying steam heated by supply water heater from a low temperature reheating steam pipe by arranging a device which controls a supply rate of the steam heated by the supply water heater during turbine bypass operation. CONSTITUTION: A bypass line 15 is arranged with respect to a bleed stoppage valve 6 arranged on a heated steam pipe 11 lead from a low temperature reheating steam pipe 8 to a supply water heater 7. In addition to that, a heating steam control valve 13 is arranged. A water supply heater outlet thermometer 13 is arranged on an outlet of the supply water heater 7, for controlling a steam flow rate of the bypass line 15. The bypass line 15 is formed at the time of starting a turbine plant and during turbine bypass operation, even when the bleed stoppage valve 6 is closed. The supply water heater 7 can be heated, while combustion is efficiently performed in a boiler. Steam is flowed into the water supply heater 7 to reduce a steam rate to a low pressure turbine bypass valve 5, and then capacity of the bypass valve 5 is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a feed water heater heating steam control device which is applied during start-up of a steam turbine plant and during special operation such as turbine bypass operation.

[0002]

2. Description of the Related Art A conventional apparatus of this type having a feed water heater heating steam source connected to a cold reheat steam pipe and having a turbine bypass system will be described with reference to FIG.

During normal operation, the steam generated in the steam generator passes through the main steam pipe 10, the high-pressure turbine 1, the low-temperature reheat steam pipe 8, the boiler reheater 3, and the high-temperature reheat steam pipe 9 to an intermediate pressure. Guided to the turbine 2.

A part of the low-temperature reheat steam that has exited the high-pressure turbine 1 in the middle of this flow passes through a low-temperature reheat steam pipe 8 through a feed water heater heating steam pipe 11 and an extraction stop valve 6 to feed water heater. Guided to 7. At this time, the high pressure turbine bypass valve 4 and the low pressure turbine bypass valve 5 are fully closed.

On the other hand, at the time of startup and turbine bypass operation, the steam generated in the steam generator passes through the main steam pipe 10 and part or all of it bypasses the high pressure turbine 1, and the high pressure turbine bypass valve 4 and low temperature It flows through the reheat steam pipe 8, the boiler reheater 3, and the high temperature reheat steam pipe 9, and a part or all of it flows to the condenser through the low pressure turbine bypass valve 5.

At this time, the extraction stop valve 6 is fully closed and the feed water heater 7 is not used for heating the feed water. Therefore, the temperature of the feed water guided to the boiler is low, the amount of fuel input to the boiler is increased, and the amount of steam passing through the low-pressure turbine bypass valve 5 is increased. Therefore, it is necessary to increase the capacity of the low-pressure turbine bypass valve 5. Yes, it is uneconomical in terms of operation and equipment, which is not preferable.

[0007]

As described above, in the conventional apparatus of this kind, the feed water heater having the heating steam pipe connected to the low temperature reheat steam pipe is supplied with water during the plant startup and the turbine bypass operation. Not being used for heating, the feed water temperature to the boiler is low, not only the amount of fuel input to the boiler increases, but also the amount of steam passing through the low pressure turbine bypass valve increases, so the capacity of the low pressure turbine bypass valve also increases. However, there is a problem in that it is uneconomical in terms of operation and equipment and is not preferable.

Therefore, the present invention aims to solve the above problems by controlling the amount of heating steam so that the feed water heater can be heated by feed water even during startup and during turbine bypass operation. To do.

[0009]

The present invention has been made to solve the above problems, and in a steam turbine plant having a system for supplying heating steam for a feed water heater from a low temperature reheat steam pipe, at start-up and turbine bypass operation. At the same time, there is provided a feed water heater control device in which a device for controlling the supply amount of the feed water heater heating steam is provided in the system.

Further, according to the present invention, the device for controlling the supply amount of the feed water heater heating steam is a feed water heater control device comprising a bypass line including a control valve which operates according to the feed water temperature at the outlet of the feed water heater. Is provided.

Furthermore, the present invention provides a feed water heater control device, wherein the device for controlling the supply amount of the feed water heater heating steam comprises a conduction valve with a positioner.

[0012]

According to the present invention, when the turbine plant is started and during the turbine bypass operation, the supply amount of the feed water heater heating steam provided in the system for supplying the feed water heater heating steam from the low temperature reheat steam pipe is controlled. By operating the device, heating steam controlled to a desired amount is supplied to the feed water heater.

Further, according to the present invention, the bypass line control valve provided in the system for supplying the feed water heater heating steam from the low-temperature reheat steam pipe is controlled according to a predetermined standard according to the feed water temperature at the outlet of the feed water heater. By doing so, the amount of heating steam in the bypass line is controlled, and a desired amount of heating steam is supplied to the feed water heater even when the extraction stop valve is fully closed.

Furthermore, according to the present invention, an electric valve with a positioner provided in a system for supplying the heating steam for the feed water heater from a low temperature reheat steam pipe is operated, that is, the feed water temperature at the outlet of the feed water heater is predicted, In response to this, the positioner is moved to a preset positioner position to obtain the intermediate opening of the motor-operated valve, thereby supplying a desired amount of heated steam to the feed water heater.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG.
In this embodiment, the heating steam pipe 1 is different from the conventional one shown in FIG.
The parts from 1 to the feed water heater have been devised, and there is no particular difference in the remaining structure from the conventional one. Therefore, the same parts as those of the conventional one are denoted by the same reference numerals, and the description of the overlapping parts will be omitted.

That is, in this embodiment, a bypass line 15 is provided for the extraction stop valve 6 on the heating steam pipe 11 from the low temperature reheat steam pipe 8 to the feed water heater 7, and the heating steam is provided here. A control valve 12 is installed.

Further, the feed water heater 7 is provided with a feed water heater outlet thermometer 13 at its outlet, and a signal taken out from the thermometer 13 is guided to a temperature comparator 14 to control a deviation ΔH from a target temperature value T. A signal can be applied to the heating steam control valve 12 to control the valve opening, that is, the steam flow rate in the bypass line 12.

Therefore, in this embodiment, the bypass line 15 is formed and the feed water heater 7 can be heated even when the extraction stop valve 6 is closed when the turbine plant is started and during the turbine bypass operation. The feed water heater 7 maintains a predetermined function and can efficiently perform combustion in the boiler.

Further, since the flow of steam into the feed water heater 7 reduces the flow rate of steam to the low pressure turbine bypass valve 5, the capacity of the low pressure turbine bypass valve can be reduced.

In the present embodiment, as described above, the bypass line 15 having the heating steam control valve 12 intervenes mainly plays a role. However, by making the extraction stop valve 6 an electric valve with a positioner, It is possible to obtain an effect equivalent to this without providing the bypass line 15.

Although not shown again, the amount of heated steam necessary to obtain the required feed water heater outlet feed water temperature expected at the time of starting the turbine plant and at the time of turbine bypass operation is obtained, and the extraction stop valve 6 corresponding thereto is obtained. By obtaining the intermediate opening degree and presetting the positioner position according to the intermediate opening degree, the desired effect can be achieved similarly to the function of the bypass line 15.

Although the present invention has been described above with reference to the illustrated embodiments, it goes without saying that the present invention is not limited to such embodiments, and various modifications may be made to its specific structure within the scope of the present invention. Nor.

[0023]

As described above, according to the present invention, since a part of the steam that has conventionally flowed in the low pressure turbine bypass valve can be used for heating the feed water, the amount thereof can be reduced and the capacity of the low pressure turbine bypass valve can be reduced.

At the same time, by supplying a part of the steam to the feed water heating, the feed water temperature can be increased more than before when starting and during turbine bypass operation, and the amount of fuel input to the boiler can be reduced.

Further, during the normal operation, the bleed stop valve is fully opened so that the heating steam system can be operated without increasing the pressure loss as in the conventional case.

[Brief description of drawings]

FIG. 1 is a system diagram showing feed water heater heating steam according to an embodiment of the present invention.

FIG. 2 is a system diagram showing a conventional feed water heater heating steam.

[Explanation of symbols]

 1 High Pressure Turbine 2 Medium Pressure Turbine 6 Extraction Stop Valve 7 Water Supply Heater 8 Low Temperature Reheat Steam Pipe 11 Water Supply Heater Heating Steam Pipe 12 Heating Steam Control Valve 13 Water Supply Heater Outlet Thermometer 14 Comparator 15 Bypass Line

Claims (3)

[Claims] 1. A steam turbine plant having a system for supplying feed water heater heating steam from a low-temperature reheat steam pipe, wherein a device for controlling the supply amount of the feed water heater heating steam is provided at the time of start-up and turbine bypass operation. A feed water heater control device characterized by being installed in a system. 2. The device for controlling the supply amount of the feed water heater heating steam is configured by a bypass line including a control valve which operates according to the feed water temperature at the feed water outlet of the feed water heater. The water heater controller as described in. 3. The feed water heater control device according to claim 1, wherein the device for controlling the supply amount of the heating steam for the feed water heater comprises a conduction valve with a positioner.