JPS6399402A - Feedwater heater drain system - Google Patents

Abstract

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

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a high pressure feedwater heater drain system for a nuclear power plant.

(Conventional technology) In contrast to the conventional method in which the drain from the high-pressure feedwater heater is sent to the low-pressure feedwater heater, recently the drain from the high-pressure feedwater heater is boosted in pressure by a pump and returned to the reactor feedwater pump suction, thereby improving plant efficiency. It is planned to adopt a method that increases the

FIG. 2 shows a configuration diagram of a general system for recovering high-pressure feedwater heater drain into a water supply line.

In FIG. 2, condensate generated in the high-pressure feed water heater a is once collected and accumulated in a drain tank j, pressurized by a drain pump i, and recovered to the water supply system via a control valve d. Hikode,
Normally, the water level in the drain tank j is determined by the water level controller, which receives the drain tank water level signal from the water level detector f installed in the drain tank j.The water level controller receives the drain tank water level signal from the water level detector f installed in the drain tank j. d.

(Problem that the invention sought to solve) In such a feed water heater drain system, if an abnormality such as a failure of the control valve d or a trip of the drain pump occurs, the drain cannot be collected into the water supply system and the water level of the drain tank will rise. Therefore, if the drain tank water level rises to N, L + α, the water level controller g will adjust the drain tank water level to N, L.
Control valve e is controlled so that L+α, and drain is collected into the condenser.

As mentioned above, if the high pressure water heater drain cannot be recovered to the water supply system, it will be unconditionally recovered to the condenser.

Therefore, there is a problem that heat cannot be recovered and thermal efficiency deteriorates.

The present invention has been made in view of the above problems, and its purpose is to:
An object of the present invention is to provide a feedwater heater drain system that can improve the thermal efficiency of the entire plant by efficiently recovering high-pressure feedwater heater drain that has a high calorific value.

(β Stage to Solve Problems) In order to achieve the above object, the present invention installs a boost pump and control valve from a drain tank that collects and stores drain from a feed water heater that heats feed water using high-pressure turbine extraction air in a nuclear power plant. It consists of a system that collects condensate to the condensate system on the suction side of the reactor feed water pump through the reactor feed water pump, a system that collects low-pressure heater hedren through a control valve, and a system that collects condensate hedrum via a control valve. The present invention is characterized in that the set values of the water level controller that outputs a control signal to each control valve are different from each other. By collecting the condensate when the drain tank water level rises to the low-pressure feed water heater, the thermal efficiency of the plant can be improved even in such a case.

(Example) An embodiment of the present invention is shown in FIG.

In FIG. 1, the drain generated in the high-pressure feed water heater 1 is once collected and accumulated in a drain tank 12, and the drain pump 11
The pressure is increased in the water supply system, and the water is recovered to the water supply system via the control valve 4. At that time, the water level of the drain tank 12 is determined by the water level controller 6 which receives the drain tank water level signal from the water level detector 5 installed in the drain tank 12 and controls the control valve so that the drain tank water level becomes the normal control value N, W, L. In systems such as those for controlling valve 4, failure of control valve 4 or drain pump 11
When an abnormality such as a trip occurs, drain cannot be collected into the water supply system and the drain tank water level rises.If the drain tank water level rises by 4 to N, W, L+α, the water level controller 7 sets the drain tank water level to the control value. N, W,
The control valve 4 is controlled so that L+α, and the drain is recovered to the low pressure feed water heater.

Furthermore, if the above-mentioned event occurs when the internal pressure difference between the high-pressure feed water heater and the low-pressure feed water heater is small, such as when the load is low, condensate cannot be recovered by the low-pressure feed water heater, so the water level in the drain tank 12 becomes N, W, beyond L+α, N, W,
When the water level reaches L+β, the water level controller 8 turns the control valve lO so that the drain tank water level becomes the control value N, W, L+β.
is recovered to the condenser.

By suppressing abnormal water level rises in the drain tank, safe plant operation can continue.

〔Effect of the invention〕

Alternatively, even in the event of an abnormality such as a drain pump trip, the high-pressure feedwater heater drain, which has a high amount of heat, is not wasted and recovered in the condenser, but is recovered in the low-pressure feedwater heater, improving the thermal efficiency of the entire plant. .

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a block diagram showing an example of a conventional system. 1...High pressure water heater, 2...Water pump, 3...
・Low pressure feed water heater, 4,9.10...Control valve, 5...
・Water level transmitter, 6, 7.8...Water level controller, 11...
・Drain pump, 12...Drain tank. Agent Patent Attorney Nori Chika Yudo Hirofumi Mitsumata

Claims (1)

[Claims] 1. Condensate from the drain tank that collects and accumulates drain from the feed water heater that heats the feed water using high-pressure turbine extraction air in a nuclear power plant, through a boost pump and control valve, to the suction side of the reactor feed water pump. It is composed of a system that collects condensate into the system, a system that collects condensate to the low-pressure heater via the control valve, and a system that collects condensate to the condenser via the control valve, and outputs a control signal to each control valve. This feed water heater drain system is characterized by having different set values for each water level controller. 2. The set value of each water level controller becomes lower in the order of the system for recovering to the reactor feed water pump suction, the system for recovering to the low pressure feed water heater, and the system for recovering to the condenser. Feedwater heater drain system as described in Section.