JPH06257416A - Shaft cooling water control device for combined cycle power plant - Google Patents

Abstract

PURPOSE:To supply the required amount of cooling water to only the bearing part of a prime mover by providing a bypass pipe provided with a valve controlled by a control circuit for detecting by means of a detector sufficient lowering of the temperature of high temperature parts having residual heat so as to close the valve. CONSTITUTION:The cooling water cooled by a cooling water-cooler flows into a serial inlets shaft cooling header l. Thereafter, the cooled cooling water is depressurized by respective shaft inlet flow rate adjusting main-valve 2, and then distributed to respective apparatuses 5 through a shaft-inlet shaft cooling header 3 and respective apparatus inlet adjusting valves 11. With a bearing cooling water supplying line 9 only, the upstream side of a shaft inlet flow rate adjusting main-valve 2 of a shaft cooling water supplying mother-pipe 6 and the upstream side of the apparatus inlet adjusting valve 11 are connected to each other by a bypass pipeline 7 containing an ON/OFF valve 8. Even when the opening of the shaft inlet flow rate adjusting main-valve 2 is minimal due to shaft-stopping, the ON/OFF valve 8 is opened. Thus, regardless of the opening of the shaft inlet flow rate adjusting main-valve 2, the required amount of cooling water can be supplied to only the bearing part of a motor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shaft cooling water control device for a prime mover bearing portion after a combined cycle power plant is stopped.

[0002]

2. Description of the Related Art Recent thermal power plants often employ a combined cycle power plant which has a short starting time and is advantageous in terms of diversification of highly efficient operation / operation and daily operation / stop. However, since the output of each axis of the prime mover is smaller than that of a normal steam power plant, multiple axes form one series, and partial load operation operates the axes for the required output (for example, 4 axes 1 series). In this plant, high efficiency operation is realized by operating 3 axes and stopping 1 axis at 75% operation. An outline of the conventional shaft cooling system of the combined cycle power generation plant as described above will be described with reference to the system diagram of FIG.

As shown in the figure, the cooling water sent out by the cooling water pump 30 is sent to a plurality of cooling water coolers 32 via a cooler inlet header 31, and after being cooled there, it is cooled. It passes through the outlet header 33 and is sent to the series inlet shaft cooling header 34. The series inlet shaft cooling header 34 is provided with each shaft cooling water supply mother pipe 41 including the shaft inlet flow rate control valve 35 by the number of shafts. The cooling water is supplied to each mother pipe 41.
After being supplied to each shaft device 38 through each shaft inlet shaft cooling header 36 and shaft device inlet control valve 37 connected to
It is returned to the cooling water pump 30 via each shaft outlet shaft cooling header 39 and series outlet shaft cooling header 40.

Such a shaft cooling water system operates only the number of cooling water coolers 32 that exchange heat in a required heat exchange amount at the time of partial load operation, and the shaft inlet flow rate control valve 35 of the stopped shaft has a minimum flow rate. Is set to a minimum opening (the cooling water pump 30 is also stopped when the load is low) to realize economical plant operation during partial load.

[0005]

In the shaft cooling water system as described above, during partial load operation, only the prime mover bearing portion (particularly of the turbine) in the shaft device 38 of the stopped shaft is in operation. Since it was exposed to high-temperature gas, it has residual heat even after the shaft is stopped, so cooling for about 2-3 hours is required. However, at the same time when the shaft is stopped, the shaft inlet flow rate control valve 35 becomes the minimum opening,
It was difficult to supply the required amount of cooling water only to the prime mover bearing.

The present invention has been made in view of the above circumstances, and its purpose is to provide only a prime mover bearing portion of a stopped shaft without losing the original purpose of realizing plant operation under economical partial load. An object of the present invention is to provide a shaft cooling water control device for a combined cycle power plant that supplies a required amount of cooling water.

[0007]

In order to achieve the above object, the present invention provides a pump for sending cooling water to a shaft composed of a prime mover and a generator, a heat exchanger for cooling this cooling water, and a cooling water. In a shaft cooling water system of a combined cycle power plant in which a plurality of shafts having a header section for equalizing pressure are combined into one series, in front of each shaft inlet flow rate control valve and high temperature component cooling line, when the shaft is stopped, each shaft is stopped. It is opened by detecting that the inlet flow rate control valve has reached the minimum opening, and after the axis is stopped, the temperature detector detects that the temperature of the high temperature component with residual heat has cooled sufficiently and closes it. It is characterized in that a bypass pipe provided with a valve to be controlled is connected so as to stably supply the required amount of cooling water to high temperature parts having residual heat even after the shaft is stopped.

[0008]

According to the present invention, even if the shaft inlet flow control valve is at the minimum opening due to shaft stop, the valve installed in the bypass pipe is opened to adjust the opening of the shaft inlet flow control valve. It is possible to supply the required amount of cooling water only from the front of the shaft inlet flow rate control valve to the prime mover bearing portion without being affected by it.

[0009]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a system configuration diagram of an embodiment of the present invention. In the figure, the cooling water cooled by the cooling water cooler flows into the series inlet shaft cooling header 1. After that, the pressure is reduced by each shaft inlet flow rate control valve 2, and is distributed to each device 5 through each device inlet control valve 11 via each shaft inlet shaft cooling header 3, and then each shaft outlet shaft cooling header 12 and series. It is returned to the cooling water pump through the outlet shaft cooling header 13. However, only the bearing cooling water supply line 9 is turned on / off from the upstream side of the shaft inlet flow rate control valve 2 of the shaft cooling water supply mother pipe 6 to the upstream side of the equipment inlet control valve 11 of the bearing cooling water supply line 9. They are connected by a bypass pipe 7 including a valve 8. Further, a check valve 10 is provided upstream of the confluence point of the bearing cooling water supply line 9 with the bypass pipe 7 to prevent backflow. next,
The configuration and operation of the ON / OFF valve 8 described above will be described with reference to the control circuit of FIG. 2 and the operation state of FIG.

As shown in the control circuit diagram of FIG. 2 (A), the ON / OFF valve 8 on the bypass pipe 7 has a shaft opening flow rate control valve minimum opening signal 22 and a bearing metal temperature low signal 21. It is a valve controlled by two signals. Two electrical signals taken into the control circuit 20 from the temperature detector 16 attached to the shaft inlet flow rate control valve 2 and the gas turbine bearing portion 15 are supplied to the exclusive OR operation circuit 23 and the logical NOT operation circuit 24. Is calculated.

That is, as shown in the exclusive OR table of FIG. 2 (B), (1) before the shaft is stopped, the shaft inlet flow rate control valve 2 is at the normal opening and the bearing metal temperature is at the normal operating temperature. , The signals of both are 0, the solution of the exclusive theoretical sum is 0, and O
The N / OFF valve 8 is fully closed 25. (2) When the shaft is stopped, the shaft inlet flow rate control valve 2 has a minimum opening of 1 and the bearing metal temperature is still higher than the low temperature set value, so it is 0.
The solution of the exclusive OR is 1, and the ON / OFF valve 8 is fully opened 26. (3) When the cooling of the gas turbine bearing is completed, the shaft inlet flow rate control valve 2 is set to 1 at the minimum opening, the bearing metal temperature is also below the set value, and 1 is output, and the exclusive OR becomes 0. , ON / OFF valve 8 is fully closed 25. As described above, the ON / OFF valve 8 has the bearing metal temperature low signal 21 and the shaft inlet flow rate adjustment source valve minimum opening signal 22.
Are controlled by two signals.

FIG. 3 is a diagram showing the time course of the shaft rotation speed, the shaft inlet flow control valve opening, the bearing metal temperature, and the ON / OFF valve electric signal. Refer to the system diagram of FIG. 1 again. And explain.

Now, when the shaft inlet flow rate control valve 2 reaches the minimum opening degree due to the shaft stop, ON / OF on the bypass pipe 7 is performed.
Until the F valve 8 is opened and the metal temperature of the motor bearing part falls below the reference value, the required cooling water amount is supplied only to the bearing cooling water supply line 9 separately from the other shaft equipment 5, and the metal temperature of the bearing part is increased. Is below the reference value, and after the safety of the bearing is confirmed, the ON / OFF valve 8 on the bypass pipe 7 is closed and the normal shaft stop state is restored.

As is clear from the above results, according to the present invention, as shown in FIG. 1, the shaft cooling water supply mother pipe 6 and the shaft cooling water supply line 9 before the shaft inlet flow rate control valve 2 can be stopped. By connecting with a bypass pipe 7 that includes an ON / OFF valve 8 that opens and closes when the motor bearing metal temperature is low, it does not depend on the opening of the shaft inlet flow rate control valve 2 and only to the engine bearing shaft cooler. It is possible to supply the required amount of cooling water. FIG. 4 is a block diagram of another embodiment of the present invention.

This embodiment is different from the embodiment of FIG. 1 in that
Only the outlet of the bypass pipe is taken out directly from the series inlet shaft cooling header 1 instead of the shaft cooling water supply mother pipe 6, and other configurations are the same, so the same portions are denoted by the same reference numerals. The description is omitted. The ON / OFF valve 8 of this embodiment is also the ON / O of the embodiment of FIG.
Of course, it is controlled similarly to the FF valve 8.

[0017]

As described above, according to the present invention,
Bypass piping and ON / OFF to conventional shaft cooling water system
With the extremely simple configuration of adding a valve, the required amount of cooling water can be supplied only to the prime mover bearing shaft cooler of the stopped shaft without losing the original purpose of realizing plant operation under economical partial load. It is extremely effective in practical use.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of a shaft cooling water system that is an embodiment of the present invention.

FIG. 2 (A) shows ON / O on the bypass pipe of FIG.
The control circuit diagram of the FF valve, the figure (B) is the figure which showed the exclusive OR table.

FIG. 3 is a diagram for explaining an operation state of FIG.

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

FIG. 5 is a system configuration diagram of a conventional shaft cooling water system.

[Explanation of symbols]

1 ... Series inlet shaft cooling header, 2 ... Shaft inlet flow rate control valve, 3
... Shaft inlet shaft cooling header, 4 ... Bearing lubricating oil cooler, 5 ... Cooling device, 6 ... Shaft cooling water supply mother pipe, 7 ... Bypass pipe, 8
… ON / OFF valve, 9… Bearing cooling water supply line, 10…
Check valve, 11 ... Equipment inlet control valve, 12 ... Each shaft outlet shaft cooling header, 13 ... Series outlet shaft cooling header, 15 ... Gas turbine bearing section, 16 ... Temperature detector, 20 ... Control circuit.

Claims (1)

[Claims] 1. A pump for sending cooling water to a shaft composed of a prime mover and a generator, a heat exchanger for cooling the cooling water, and a plurality of shafts each having a header section for equalizing the pressure of the cooling water. In the shaft cooling water system of the combined cycle power plant, the front of each shaft inlet flow rate control valve and the high temperature component cooling line were detected when the shaft was stopped and each shaft inlet flow control source valve reached the minimum opening degree. After the shaft is stopped and the shaft is stopped, the temperature detector detects that the temperature of the high temperature component with residual heat has cooled sufficiently and closes it.Connect the bypass pipe with the valve controlled by the control circuit. A shaft cooling water controller for a combined cycle power plant, which is configured to stably supply a required amount of cooling water to high temperature parts having residual heat.