JPH01203805A - Method and device for controlling condensate system - Google Patents

Abstract

PURPOSE:To prevent the occurrence of an excessive flow rate, to ensure the stable continuous feed of water, and to stabilize transmission of power, by a method wherein, when a turbine bypass valve is opened during output operation of a plant, a part of condensate flowing through a condensate purifying device is forced to bypass. CONSTITUTION:A bypass pipe 23 and a bypass valve 22 are situated to a condensate filtering device, a check valve 24 is located in the outlet pipe of a low pressure drain pump 16, and a second low pressure drain up pipe 26, connected to the upper stream of the check valve and a condensate pipe on the downstream side of a condensate desalting device 10, and a second drain valve 25, are provided. When a turbine bypass valve is opened during rated operation, the filter device bypass valve 22 and the second low pressure drain valve 25 are opened by interlock. Operation can be executed such that an amount of water process by a condensate filtering device 9 and a desalting device 10 does not exceed a normal rated operation flow rate. Since an excessive flow rate does not flow to the condensate desalting devices 9 and 10, the pressure loss of a condensate system is prevented from increasing, pressures at the inlets of a high pressure condensate pump 11 and a water feed pump 13 can be ensured, and a loss of feed water to a steam generator due to damage of a pump and a pump trip can be prevented from occurring.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a condensate water supply system for a power plant, and more particularly to a condensate control method and apparatus for supplying stable water supply to a steam generator.

[Conventional technology]

Although there is a known example (Japanese Patent Laid-Open No. 105495/1983) regarding a conventional water supply system to a steam generator, the problems of the conventional system will be explained with reference to FIG.

Steam generated in the steam generator 1 enters a high-pressure turbine 3 to perform work, and is supplied to a low-pressure turbine 5 via a moisture separator 4 to rotate the turbine. Steam exhausted from the turbine is condensed in a condenser 7 and becomes condensate. The condensate is pumped by condensate pump 8. Condensate filtration system! ! 9. Condensate desalination equipment 10. High pressure condensate pump 11° low pressure feed water heater 12. Water pump 13.
It passes through the high pressure feedwater heater 14 and returns to the steam generator 1 .

On the other hand, the steam extracted from the middle of the turbine exchanges heat with the feed water in the feed water heaters 12 and 14 and becomes drain (condensed water). The high-pressure drain is collected in a high-pressure drain tank 18, increased in pressure by a high-pressure drain pump 19, and directly collected at the inlet of the water supply pump 13 via a high-pressure drain tank water level adjustment valve 20. The low-pressure drain is collected in a low-pressure drain tank 15, raised in pressure by a low-pressure drain pump 16, and directly collected upstream of the condensate desalination device 10 via a low-pressure drain tank water level adjustment valve 17.

Here, the water supply flow rate to the steam generator 1 is such that the water supply water level in the steam generator 1 is constant, and the water supply is equivalent to the main steam flow rate.
Water is supplied by adjusting the rotation speed of the water supply pump 13.

[Problems to be Solved by the Invention j] In the condensate system and heater drain system of the prior art described above, when the system frequency of the power transmission system of the generator increases transiently, the turbine/inlet adjustment is adjusted to prevent the turbine from overspeeding. Since the valve 2 is throttled and the amount of steam flowing into the turbine is reduced, the excess main steam is transferred to the turbine bypass pipe 22.
directly into the condenser. In this case, since the amount of steam flowing into the turbine decreases to about 60%, the amount of oil flowing into the heater also decreases almost proportionally. On the other hand, since the amount of water supplied to the steam generator is required to be constant (100% flow rate), the amount of water fed from the condenser 7 will be greater than during normal operation.

However, in a condensate system equipped with a drain pump,
Generally condensate purification equipment! 9, 10, since the processing capacity of the condensate pump 8 is designed at the normal operating flow rate (approximately 55%), the condenser 7
When the flow rate from the condensate purification device 9 exceeds the normal operating flow rate,
, 10 and high pressure condensate pump 11 and water supply pump 13.
As the inlet pressure of the plant decreases, the water supply pump stops (trips), resulting in a loss of water supply capacity and a plant scram.

An object of the present invention is to prevent the condensate purification device 9 from opening when the turbine bypass valve 21 opens when the frequency of the power transmission system increases as described above.
By bypassing the amount of condensate passing through , 10, the purpose is to prevent excessive flow, ensure stable continuous water supply, and achieve stable power transmission.

[Means to solve the problem]

The present invention was developed through detailed study of condensate control methods in order to improve the operability of power transmission systems in power generation plants in recent years. When it is necessary to send water to the steam generator at a flow rate higher than the water flow rate, this can be achieved by reducing the amount of condensate treated by the condensate purification device and bypassing a portion of the condensate that passes through the condensate purification device. Ru.

[Effect]

When the turbine bypass valve opens during normal operation of the power plant, the flow rate of condensate from the condenser increases compared to during normal operation. When this condition occurs, a part of the condensate that passes through the condensate purification device with the largest pressure loss in the condensate system is bypassed to prevent damage to the condensate purification device due to excessive flow. In addition, the inlet pressure of the high-pressure condensate pump and water supply pump on the downstream side does not decrease, so a stable water supply can be ensured.

Another invention is that by reducing the output of the steam generator when the turbine by-pipe valve opens, the condensate flow rate required from the steam generator becomes less than the processing capacity of the condensate purification system, resulting in stable Water supply can be secured.

〔Example〕

The present invention is generally applicable to devices that recover feedwater heater drain directly into the water supply system.

FIG. 1 shows an example of this. Steam generated in the steam generator 1 enters the high pressure turbine 5 via the turbine high pressure controller 2 to perform work, and passes through the moisture separator 4 to the low pressure turbine 5.
supplied to rotate the turbine. Steam exhausted from the turbine is condensed in a condenser 7 and becomes condensate. The condensate is pumped by condensate pump 8. Condensate filtration device 9, condensate desalination device 10, high pressure condensate pump 11, low pressure feed water heater 12, feed water pump 13,
It passes through the high pressure feedwater heater 14 and returns to the steam generator 1 .

On the other hand, the steam extracted from the middle of the turbine exchanges heat with the feed water in the feed water heater 12.14 and becomes drain (condensed water). High and low drains are collected in a high-pressure drain tank 18, raised in pressure by a high-pressure drain pump 19, and directly collected at the inlet of the water supply pump 13 via a high-pressure drain tank water level adjustment valve 20. Further, the low pressure drain is collected in the low pressure drain tank 15, the pressure is increased by the low drain pump 16, and the low pressure drain is directly recovered upstream of the condensate desalination device 10 via the low pressure drain tank water level adjustment valve 17.

Further, when the frequency of the power transmission system increases during normal operation, the turbine control valve 2 is throttled down and a turbine bypass valve 21 is provided to discharge excess main steam directly to the condenser.

The difference between FIG. 1 and the conventional technology is that a bypass pipe 23 and a bypass valve 22 are provided in the condensate filtration device, and a check valve 24 is provided in the outlet pipe of the low-pressure drain pump 16, and the condensate is desalinated from the upstream side. A second low-pressure drain up pipe 26 and a second drain valve 25 connected to the downstream condensate pipe of the device R10 are provided.

Here, if the turbine bypass valve opens during rated operation, the filtration device bypass valve 22 and the second low pressure drain valve 25 are opened by the interlock shown in FIG. Changes in the flow rate in the system when the present invention is adopted are shown in the boxes in FIG. 1 as a ratio to the water supply flow rate, as shown in the box ((normal time) → (when the turbine bypass valve is open)). As is clear from this figure, the condensate filtration device 9 and the desalination device 10 can be operated without the amount of treated water exceeding the normal rated operating flow rate.

In addition, since an excessive flow rate does not flow into the condensate purification devices 9 and 10, the pressure loss in the condensate system does not become large, and the inlet pressure of the high-pressure condensate pump 11 and the water supply pump 13 can be ensured, preventing damage to the pumps or pump trips. Loss of water supply to the steam generator can also be prevented.

FIG. 3 shows another embodiment of the invention. In the condensate system, a condensate flow meter 30, a condensate inlet valve 32 to the high pressure drain tank that sends condensate from the outlet of the low pressure condensate pump 8 to the high pressure drain tank 18. A condensate inlet valve 31 and its connection piping 34 are provided to the low-pressure drain tank 15 to send condensate to the low-pressure drain tank 15. If the amount exceeds 100%, the condensate inlet valves 31 and 32 to the high-pressure and low-pressure drain tanks are opened, as shown in the interlock diagram in FIG.

In this way, the amount of water that decreases in the amount of drain from the heaters 14 and 12 will be sent through the drain pump 16.19 without passing through the condensate purification device 9.10.
, 10, an excessive flow rate will not flow.

In the embodiment shown in FIG. 6, main steam from the steam generator 1 is sent to the high pressure heater 14. Main steam introduction pipe 37 leading to the low pressure heater 12.
38 and stop valves 35 and 36, as shown in the interlock diagram in Fig. 7, the turbine bypass valve 21
The stop valves 35 and 36 from the main steam are opened at the open signal. According to this embodiment, the decrease in the amount of oil flowing from the turbines 3 and 5 to the heaters 14 and 12 is replenished with surplus main steam flowing from the turbine bypass valve 21 to the condenser 7, so that the amount of drain is reduced. is equivalent to normal operation,
On the other hand, since the turbine bypass amount is reduced, the amount of condensate is also the same as in normal operation, and an excessive flow rate does not flow into the condensate purification device 9.10. The embodiment of FIG. 8 is a condensate flow meter 4.
1. Condensate purification device inlet flow meter 40. Bypass flow meter 42
．． A bypass valve 43 is provided to bypass the condensate purification device, and the opening of the bypass valve 43 is controlled so that the flow rate of water to the condensate purification device does not exceed its capacity.

Further, when the capacity of the condensate pump 8 is insufficient, the water supply amount is ensured by starting the condensate pump on standby.

The embodiment shown in FIG. 9 is a system in which the output of the steam generator 1 is lowered in order to reduce the amount of steam generated by the steam generator 1 when the turbine bypass valve is opened. In this case, the electrical output will not recover even when the frequency returns to normal conditions, but if the frequency continues to rise for a long time, it is advantageous from the viewpoint of thermal efficiency and stable water supply.

The embodiment described above is one embodiment of the invention.

By combining each elemental invention, a highly reliable and optimal condensate system can be obtained.

Furthermore, due to an increase in the frequency of the power transmission system, the operating conditions of the condensate system will be different from normal operation as in the above example, but even if the frequency returns to normal and the turbine bypass valve closes, it will not be particularly helpful for continuous operation. I can't discipline it. For this reason, when one frequency becomes stable, the bypass valve of the condensate purification device, which was opened, is closed.

〔Effect of the invention〕

INDUSTRIAL APPLICATION This invention can be applied to the condensate system which employs the drain up system which collect|recovers the heater drain directly to a condensate system of a nuclear power plant and a hydroelectric power plant, and has the following effect.

1. When the frequency of the power transmission system increases, damage to the condensate purification device, condensate pump, and water supply pump can be avoided, and stable water supply to the steam generator is possible.

2. According to the present invention, even when the frequency increases transiently, there is no need to reduce the output of the steam generator,
When the frequency returns to normal, the original electrical output can be ensured again, greatly improving operability.

[Brief explanation of the drawing]

FIGS. 1 and 2 are explanatory diagrams of the present invention, FIGS. 3 and 4 are explanatory diagrams of other embodiments of the present invention, and FIG. 5 is an explanatory diagram of a conventional condensate water supply system and heater drain system. 6 to 9 show explanatory diagrams of other embodiments of the present invention. 1...Steam generator, 2...Turbine control valve, 3...
・High pressure turbine, 4... Moisture separator, 5... Low pressure turbine, 6... Generator, 7... Condenser, 8... Low pressure condensate pump, 9... Condensate Filtration device, 10... Condensate desalination device, 11... High pressure condensate pump, 12... Low pressure feed water heater, 13... Water feed pump, 14... High pressure feed water heater, 15...・Low pressure drain tank, 16...Low pressure drain pump, 17...Low pressure drain tank water level control valve, 18...High pressure drain tank, 19...High pressure drain pump, 20...High pressure drain tank water level control valve ,2
1... Low pressure drain pump outlet pipe, 22... Condensate filtration device bypass valve, 23... Condensate filtration device bypass pipe,
24...Low pressure drain pump outlet check valve, 25...Low pressure drain pump outlet bypass valve, 26...Low pressure drain pump outlet bypass pipe, 27...Bypass valve control device, 3o...Flow rate detector , 31...Low pressure drain tank condensate inlet valve, 31...High pressure drain tank condensate inlet valve,
33... Condensate inlet valve control device, 35.36... Main steam introduction valve, 37.38... Main steam introduction pipe, 41, 42
．． 42...Flow rate detector, 43...Condensate purification device bypass valve, 44...A inno(s) Fig. 2 Fig. 4 Fig. 7 Fig. 9

Claims (1)

[Claims] 1. A main steam pipe that sends steam from a steam generator of a power plant to a main turbine, a turbine bypass pipe and bypass valve that branches from the main steam pipe and leads to a condenser, and Two or more condensate pumps that send condensate to the steam generator, a condensate purification device installed downstream of the condensate pump, a feedwater heater that heats the feedwater, and a condensate system that connects the drain of the feedwater heater to the condensate system. In a condensate system and a heater drain system, which are composed of a drain pump that directly recovers water from the water and piping that connects them, if the turbine bypass valve opens during plant output operation, part of the condensate that passes through the condensate purification device A condensate flow rate control method characterized by bypassing. 2. Main steam pipe that sends steam from the steam generator of the power plant to the main turbine; turbine bypass piping and bypass valve that branches from the main steam pipe to the condenser; and condensation from the condenser to the steam generator. Two or more condensate pumps that deliver water, a condensate filtration device and a condensate desalination device installed downstream of the condensate pump, a feedwater heater that heats the feedwater, and a condensate demineralizer that heats the feedwater heater drain. In the condensate water supply system and heater drain system, which are composed of a drain pump that directly collects condensate into the upstream condensate system of the salt equipment, and piping that connects them, a condensate bypass pipe and valve that bypasses the condensate filtration device are installed, and , a check valve is provided on the drain pump outlet piping, and piping and valves are provided that branch from the upstream side and connect to the downstream side of the condensate desalination device, and the condensate filtration device bypass is activated by the opening signal of the turbine bypass valve. A condensate flow rate control device characterized by opening a valve and an additional drain pump outlet side bypass valve. 3. In the condensate water supply system and heater drain system according to claim 2, the condensate bypass pipe and valve that bypass the condensate filtration device and the condensate bypass pipe branched from the drain pump outlet pipe and downstream of the condensate desalination device A bypass pipe and a valve are provided to connect to the condensate filter, and a flow meter is provided on the outlet side of the condensate pump, so that when the condensate flow rate exceeds a specified value, A condensate flow rate control device characterized by opening a valve. 4. In the condensate water supply system and the heater drain system according to claim 2, a condensate inlet pipe and a valve are provided to send condensate from the outlet pipe of the condensate pump to the inlet side of the drain pump, and the turbine bypass valve is opened. A condensate flow rate control device, characterized in that the condensate inlet valve is opened in response to a signal. 5. In the condensate flow rate control device according to claim 2, a flow meter is provided in the inlet pipe of the condensate filtration device, and a bypass valve provided in the condensate filtration device bypass pipe is opened by a signal from the flow meter. A condensate flow rate control device that controls the flow rate of condensate and prevents the flow rate flowing into a condensate filtration device from exceeding a specified value. 6. The condensate flow rate control device according to claim 2, wherein the condensate pump on standby is activated when the turbine bypass valve opening signal or the condensate flow rate exceeds a specified value. Water flow control device. 7. In the condensate water supply system and heater drain system according to claim 2, a main steam introduction pipe and a stop valve are provided to directly introduce main steam from the steam generator to the feed water heater, and a turbine bypass valve is opened. A condensate flow rate and main steam control device characterized by opening a stop valve of the main steam introduction pipe in response to a signal. 8. Turbine bypass piping and bypass valve that bypass the main turbine of the power plant to the condenser, two or more feed water pumps that send water from the condenser to the steam generator, and In the condensate water supply system and heater drain system, which are composed of a feedwater heater to heat the feedwater heater, a drain pump that directly collects the drain from the feedwater heater to the upstream condensate system of the condensate desalination equipment, and piping that connects them, the turbine A water supply control device characterized in that one of the water supply pumps is stopped or the water supply flow rate of the water supply pump is reduced in response to an opening signal of a bypass valve. 9. In the condensate water supply system and heater drain system according to claim 8, when the turbine bypass valve opens and the main turbine output decreases, the flow rate of steam generated by the steam generator is adjusted according to the main turbine output. Steam generator control device characterized by reduced