JPS63176904A - Boiler feed pump protective device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to ensuring the operating suction pressure of a boiler feed water pump in a power generation plant, and in particular to reducing the heat of the deaerator downcomer pipe during a transient drop in deaerator pressure. The present invention relates to a device suitable for rapidly replacing water with low-temperature feed water to ensure the operating suction pressure of a boiler feed water pump.

[Conventional technology]

As described in Japanese Unexamined Patent Publication No. 58-99603, the conventional device is a system installed in parallel to replace hot water in the suction pipe of a boiler feed pump when the boiler feed pump is stopped. The suction sides of multiple water pumps were connected to each other.

[Problem that the invention seeks to solve]

The above conventional technology replaces the hot water in the suction pipe of the stopped boiler feed pump with low-temperature feed water when the plant load reduction rate and reduction width exceed a certain value, respectively. No consideration was given to securing the required suction head when the water pump was in operation.

The purpose of the present invention is to promptly replace the hot water accumulated in the suction side piping of the boiler feed water pump in operation with cold water when the rate and width of the decrease in the plant load respectively exceed set values. The objective is to secure the required suction head of the boiler feed pump during operation.

[Means for solving problems]

The above purpose was to install a pipe to send the discharge water of the boiler feed pump to the deaerator water storage tank from the water supply pipe on the discharge side of the boiler feed pump, and to ensure that the load reduction rate and load reduction width exceeded the set value. 6 [Function] The present invention is achieved by opening the circulation valve installed in the pipe line only when the hot water in the inlet pipe of the boiler feed water pump is in operation is immediately replaced with low temperature feed water. , a pipe line was provided from the water supply pipe on the discharge side of the boiler feed water pump to the deaerator water storage tank via a circulation valve.

The circulation valve opens when the plant load reduction rate and load reduction width exceed set values, and the boiler feed water pump discharge water is sent to the deaerator water storage tank through the pipe line.

As a result, the hot water on the suction side of the boiler feed water pump is quickly replaced with low-temperature feed water, so the hot water on the suction side of the boiler feed water pump does not flash. On the other hand, if the plant load reduction rate and load reduction width are below the set values, the main circulation valve is closed.

〔Example〕

FIG. 1 is a conceptual diagram of a water supply system in a power generation plant equipped with a boiler feed pump protection device according to the present invention. The steam that has completed its work in a turbine (not shown) is condensed in a condenser 1, raised in pressure by a condensate pump 2 as condensate, and sent to a degassing chamber 5 via a condensate pipe 3 and a low-pressure feedwater heater 4. The water is heated and degassed by steam from the heating steam pipe 7, and the water is stored in the deaerator water storage tank 6.

During normal operation of the power plant, the number of boiler feed pumps is two, so for the purpose of explanation using a single diagram, the boiler feed pump is II.
It is assumed that A.IIB is operating. Water is supplied from the deaerator water storage tank 6 through downcomer pipes 8A and 8B, to the boiler feed water boost pump inlet stop valves 9A and 9B, and to the boiler feed water boost pump 10A.

10B, boiler feed water pump IIA, IIB, boiler feed water pump outlet check valve 12A, 12B, and same outlet stop valve 13A
, 13B to a boiler (not shown), and then again to the turbine as steam.

A feature of the present invention is that in the water supply system from the deaerator to the boiler, a conduit 17 is additionally installed for conveying water discharged from the boiler water supply pump from the water supply pipe 14 to the deaerator water storage tank 6, A circulation valve 15 and an orifice 16 are provided in the pipeline.

During plant operation, when the load reduction rate and load reduction width of the plant exceed the set values, the circulation valve 15 installed in the pipe line 17 is opened, so the downcomer pipes 8A and 8B
Boiler feed water boost pumps IOA and IO
The required operating suction head of B can be secured. This is because hot water on the suction side of the boiler feedwater boost pumps IOA and IOB tends to flush as the deaerator pressure decreases due to a sudden reduction in plant load. Flash can be prevented by replacing. The invention also operates with a control block as shown in FIG. In other words.

The circulation valve 15 opens (block 20) when the plant load reduction rate and load reduction width are greater than or equal to the set values (block 18).
．． 19) (when the AND condition is met), the circulation valve 15 is in the closed state (block 21) under conditions other than the above.

According to the present invention, even when the plant load reduction rate and load reduction width exceed the set value due to sudden load reduction,
The increase in the amount of water supplied by opening the circulation valve 15 makes it possible to quickly replace hot water, and the boiler feed water boost pump IOA,
Since the required operating suction head of the IOB can be secured, burnout of the pump can be prevented.

[Effects of the Invention] According to the present invention, when a sudden load reduction occurs, by sending the discharge water of the boiler feed pump from the water supply pipe to the deaerator water storage tank, the flow rate passing through the boiler feed pump is increased.
Since the hot water stagnant on the suction side of the pump can be quickly replaced with low-temperature water supply, the necessary operating suction head of the pump can be secured and burnout can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a water supply system diagram in a power generation plant equipped with a boiler feed pump protection device according to an embodiment of the present invention, and FIG. 2 is an automatic control block diagram.

Claims (1)

[Claims] 1. In a power generation plant that has a water supply system with a deaerator, separate downpipe that connects the boiler feed pump, and a water supply pipe that connects the boiler feed pump to the boiler, the load reduction rate and load of the power plant When the drop width exceeds the set value, the above steps are taken to shorten the time required to replace hot water with low-temperature feed water in the downcomer pipe and the boiler feed pump suction pipe, which are the suction side pipes of the boiler feed pump in operation. A boiler feed pump protection device, characterized in that it is provided with a conduit and a control device for sending water discharged from the boiler feed pump to a deaerator water storage tank from the water supply conduit.