JP2934984B2 - Steam motor plant - Google Patents

Description

The present invention relates to a steam motor plant, and more particularly to a steam motor plant. The present invention relates to a steam motor plant capable of supplying a stable water supply to a steam generator.

[Conventional technology]

As a conventional condensate water supply system, particularly related to a drain pump system (as described in JP-A-63-223403)
There is. For the same drain pump system as this conventional example,
This will be described with reference to FIG.

The steam generated by the steam generator 1 enters the high-pressure turbine 3 via the steam generator outlet valve 2 to perform work, and the exhaust steam of the high-pressure turbine 3 is supplied to the low-pressure turbine 5 via the intermediate steam stop valve 4. Then, the turbine is rotated to drive the generator 6. The steam exhausted from the low-pressure turbine 5 is condensed in the condenser 7 to be condensed. This condensate is condensed
The water is returned to the steam generator 1 through the low-pressure feed water heater 10, the feed water pump 11, and the high-pressure feed water heater 12. On the other hand, the steam extracted from the middle of the high-pressure turbine 3 exchanges heat with the feed water in the high-pressure feed water heater 12 to become drain (condensed water), and is collected in the high-pressure drain tank 14. The drain stored in the tank 14 is pressurized by a high-pressure drain pump 17 through a high-pressure drain pump inlet valve 16, passes through a high-pressure drain pump outlet valve 18, passes through a high-pressure drain tank water level control valve 19, and is supplied to a water supply pump.
Collected directly at 11 entrance. Condensed water (cold water) from the outlet of the low-pressure feed water heater 10 is directly injected into the high-pressure drain tank 14 through the condensate supply valve 28. Further, a gate valve 29 for closing the pressure equalizing pipe for balancing the internal pressures of the high pressure feed water heater 12 and the high pressure drain tank 14 is used.
Are provided. Here, the sluice valve 29 and the condensate make-up water valve 28 are switched as necessary through a switching means 27, and are switched based on a detection signal of the electric output detector 26 at the time of a plant transient change. Means 27 compares the detected value with the set value, switches valves 28 and 29, and controls the pressure in drain tank 14.

[Problems to be solved by the invention]

In the above conventional drain tank pressure control system,
When the load of the turbine generator 6 is interrupted or the like and the plant output changes suddenly, the internal pressure of the drain tank 14 shown in FIG. At this time, the drain of the drain pump inlet pipe does not follow the pressure control of the drain tank, so that a flush phenomenon occurs. When this flush phenomenon occurs, the drain pump 17 trips to protect the pump. Further, in the condensate water supply system in which the drain pump 17 is installed, generally, the condensate water supply capacity of the condensate pump 8 is only about 60% of the total amount of water supply. For this reason,
If the drain pump 17 trips, the drain pump
As a result, the water supply from the water supply 17 disappears, the condensate pump 8 runs out, the inlet pressure of the water supply pump 11 decreases, and the water supply pump 11 stops (trips) to protect the water supply pump 11. Therefore. There is a risk that the water supply capacity will be lost and the steam generator 1 will be scrammed (automatically stopped).

SUMMARY OF THE INVENTION An object of the present invention is to provide a steam motor plant capable of preventing a drain pump from tripping and stably supplying water to a steam generator even when a plant output greatly changes such as when a load is cut off.

[Means for solving the problem]

The above object is to return a part of the water supplied from the low-pressure feed water heater to respective inlet pipes of a plurality of drain pumps provided in parallel, and to return the drain pump inlet side provided respectively to the cold water pipes. This is achieved by providing a chilled water injection valve that adjusts the amount of chilled water injection, and a control device that controls the opening and closing of each chilled water injection valve according to the number of operating or standby units of the drain pump.

(Operation)

When the plant output decreases sharply, or when the amount of steam injected from the generator into the turbine decreases, such as when the load is rejected, the pressure inside the drain tank drops significantly. However, the inlet pressure of the drain pump is ensured and the pump is operated within the water supply capacity range. A stable suction flow rate can be secured in the water supply pump.

In addition, when the drain pump trips, the required inlet pressure can be secured for the drain pump of the standby machine, and stable continuous water supply to the steam generator can be secured.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a configuration diagram of a steam motor plant according to one embodiment of the present invention. The steam generated by the steam generator 1 is
The steam enters the high-pressure turbine 3 through the steam generator outlet valve 2 and performs work. The exhaust steam of the high-pressure turbine 3 is supplied to the low-pressure turbine 5 through the intermediate steam stop valve 4, and rotates the turbine 5 to drive the generator 6. The steam exhausted from the turbine 5 is condensed in the condenser 7 to be condensed. The condensate is condensate pump 8, condensate flow rate detector 9, low pressure feed water heater 10, feed water pump 1
1. It is returned to the steam generator 1 through the high pressure feed water heater 12.

On the other hand, the high-temperature steam extracted in the middle of the high-pressure turbine 3 exchanges heat with the feedwater in the high-pressure feedwater heater 12 to become drain (condensed water). The high-pressure drain is supplied to the high-pressure drain tank 14
In this embodiment, the pressure is increased by a high-pressure drain pump 17 via three high-pressure drain pump inlet valves 16 provided in parallel, passes through a high-pressure drain pump outlet valve 18, and is connected to a high-pressure drain tank water level control valve 19. Via the feedwater pump 11 directly. Further, a part of the condensed water is directly injected from the outlet of the low-pressure feed water heater 10 into the inlet pipe of each high-pressure drain pump 17 through three high-pressure drain pump cold water injection valves 21 provided in parallel.

Here, the amount of cold water injected into the inlet pipe of each high-pressure drain pump 17 is adjusted so that the inlet pressure of the pump 17 can be ensured even when a flush phenomenon occurs in the drain tank 14 or in the pipe connected thereto. Pump operation number judgment device
24 and a high-pressure drain pump chilled water injection controller 23. As a method of changing the chilled water injection amount itself, the start, stop, or standby state of the high-pressure drain pump 17 is determined by the high-pressure drain pump operating number determination device 24,
The control is performed by a request signal from the high-pressure drain pump cold water injection control device 23.

In the above condensate water supply system, it is assumed that the load on the turbine generator 6 is cut off and the steam generated by the generator 1 is rapidly reduced. In this case, the internal pressure of the high-pressure drain tank 14 drops remarkably transiently, so that a drain flush phenomenon occurs at the inlet piping of the high-pressure drain tank 14 and the high-pressure drain pump 17. For this reason, the required inlet pressure of the high-pressure drain pump 17 cannot be secured. Therefore, in the drain pump chilled water injection system, the high pressure drain pump operation number determination device 24 and the high pressure drain pump chilled water injection control device
When the high pressure drain pump 17 is operating, the inlet pipe chilled water injection valve 21 of the operating high pressure drain pump 17 is fully opened, and the standby high pressure drain pump 17 is also Then, the cold water injection valve 21 for the high pressure drain pump inlet pipe is fully opened to secure the inlet pressure of the high pressure drain pump 17. Thereby, abnormality of the high-pressure drain pump 17 or pump trip can be prevented, and the flow rate of water supply to the water supply pump 11 can be ensured. In addition, there is an effect even if cold water injection is applied only to the high-pressure drain pump 17 during operation.

FIG. 2 is a configuration diagram of a power plant according to a second embodiment of the present invention. The concept of the high pressure drain pump cold water injection is the same as that of the first embodiment of FIG. 1, but in order to make the cold water injection more effective, in addition to the configuration of the first embodiment, a high pressure drain pump inlet mother pipe is further provided. A cold water injection valve 20 to 30 is installed. Then, in the same manner as in the first embodiment, the injection valves 20, 21
By injecting the chilled water, the amount of cold water to be injected is equal to the number of operating units or the number of operating units and the standby amount.

FIG. 3 is a configuration diagram of a power plant according to a third embodiment of the present invention. In the condensate water supply system, a condensate flow value judging device 25 which is operated by the detection signal of the condensate flow detecting device 9 is installed. Full-open control or open control of the drain pump inlet mother pipe cold water injection valve 20 is performed. Further, a high-pressure drain pump operation number determination device 24 and a high-pressure drain pump cold water injection control device
With 23, the number of operating high-pressure drain pumps 17 causes the high-pressure drain pump inlet pipe cold water injection valve 21 to be fully opened. In the present embodiment, similarly to the first embodiment, by securing the inlet pressure of the high-pressure drain pump 17, it is possible to prevent an abnormality of the high-pressure drain pump 17 or to prevent a pump trip. Can be secured.

FIG. 4 is a configuration diagram of a power plant according to a fourth embodiment of the present invention. The concept of the high-pressure drain pump cold water injection is the same as that of the third embodiment, but only the high-pressure drain pump inlet main pipe cold water injection valve 20 is used to further simplify the cold water injection system. The cold water injection amount is for the number of operating pumps 17 or for the number of operating pumps and the standby. In this manner, the number of failure factors in the system is reduced, the required inlet pressure of the high-pressure drain pump 17 can be secured, and stable water supply to the steam generator 1 can be secured.

FIG. 5 is a configuration diagram of a power plant according to a fifth embodiment of the present invention. The concept of the high pressure drain pump cold water injection is the same as that of the fourth embodiment. However, in order to further simplify the cold water injection system, only the high pressure drain pump inlet mother pipe injection valve 20 is used. Is installed, and when the condensed water flow reaches 50% or more of the rated condensed water flow, the high pressure drain pump inlet mother pipe cold water injection valve 20 is fully opened or controlled. In this way, the causes of system failure are reduced,
The required inlet pressure of the high-pressure drain pump 17 can also be secured, and stable water supply to the steam generator 1 can be secured.

〔The invention's effect〕

ADVANTAGE OF THE INVENTION According to this invention, the following effects are obtained by applying to the condensate water supply system which employs the feed water heater drain pump in the steam motor plant such as a nuclear power plant or a thermal power plant.

(A) Drain pump damage and drain pump trip can be prevented by a flush phenomenon in the inlet piping of the high-pressure drain pump due to a drop in the internal pressure of the high-pressure drain tank, such as when the output of the plant suddenly drops. The reliability of the condensate water supply system is improved.

(B) When the output of the plant suddenly drops or the high-pressure drain pump trips, the required inlet pressure of the standby drain pump can be secured, and a stable water supply to the steam generator can be provided.

[Brief description of the drawings]

FIG. 1, FIG. 2, FIG. 3, FIG. 4, and FIG.
FIG. 6 is a configuration diagram of a power plant according to the first, second, third, fourth, and fifth embodiments, and FIG. 6 is a configuration diagram of a conventional power plant. 1 ... steam generator, 3 ... high-pressure turbine, 5 ... low-pressure turbine, 6 ... turbine generator, 7 ... condenser, 8 ...
Condenser pump, 9 Condensate flow rate detection device, 10 Low pressure feed water heater, 11 Feed water pump, 12 High pressure feed heater, 13
…… water supply flow meter, 14 …… high pressure drain tank, 16 …… high pressure drain pump inlet valve, 17 …… high pressure drain pump, 20 ……
High pressure drain pump inlet mother pipe cold water injection valve, 21 High pressure drain pump inlet pipe cold water injection valve, 23 High pressure drain pump cold water injection control device, 24 High pressure drain pump operation number judgment device, 25 Condensate flow rate Value judging device, 30 ... Inlet main pipe.

Claims (3)

(57) [Claims] 1. A steam generator, a high-pressure turbine that performs work by introducing steam generated by the steam generator, a low-pressure turbine that performs work by introducing exhaust steam from the high-pressure turbine, and the low-pressure turbine. A condenser that returns the exhaust steam of the
A condensate pump for pressurizing the condensate of the condenser and sending the water, a low-pressure feedwater heater provided downstream of the condensate pump for heating the feedwater from the condensate pump, and a feedwater from the low-pressure feedwater heater A high-pressure feed water heater that receives a supply of pressurized feed water by the feed water pump, heats the feed water with extracted steam of the high-pressure turbine, and returns the feed water to the steam generator. In a steam motor plant including a drain tank for storing a drain of heated steam from a high-pressure feed water heater and a plurality of drain pumps provided in parallel to pressurize the drain and return it to the feed water pump inlet, the low-pressure feed water heating is performed. A chilled water pipe for returning a part of the water supply from the vessel to the respective inlet pipes of the plurality of drain pumps provided in parallel, and a chilled water injection amount for each of the chilled water pipes and returned to the drain pump inlet side. Cold water Iriben and, the number of operating units or steam engine plant, characterized in that it comprises a control device controls the opening and closing of the cold water injection valve each in accordance with the waiting number of the drain pump. 2. A steam generator, a high-pressure turbine that performs work by introducing steam generated by the steam generator, a low-pressure turbine that performs work by introducing exhaust steam from the high-pressure turbine, and the low-pressure turbine. A condenser that returns the exhaust steam of the
A condensate pump for pressurizing the condensate of the condenser and sending the water, a low-pressure feedwater heater provided downstream of the condensate pump for heating the feedwater from the condensate pump, and a feedwater from the low-pressure feedwater heater A high-pressure feed water heater that receives a supply of pressurized feed water by the feed water pump, heats the feed water with extracted steam of the high-pressure turbine, and returns the feed water to the steam generator. In a steam motor plant including a drain tank for storing a drain of heated steam from a high-pressure feed water heater and a plurality of drain pumps provided in parallel to pressurize the drain and return it to the feed water pump inlet, the low-pressure feed water heating is performed. A chilled water pipe that always returns a part of the chilled water from the vessel to the respective inlet pipes of the plurality of drain pumps provided in parallel, and a chilled water injection amount that is respectively provided in the chilled water pipe and returned to the drain pump inlet side. Do A water injection valve, the number of operating units or steam engine plant, characterized in that it comprises a control device controls the opening and closing of the cold water injection valve each in accordance with the waiting number of the drain pump. 3. The steam motor plant according to claim 1, wherein the control device controls a chilled water injection valve according to a condensate flow rate.