JP3977960B2 - Condensate pump control system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention has a condenser high water level control device that discharges out of the system from the outlet of the condensate pump in a thermal power plant, and operates the condenser high water level control device when one of the condensate pumps trips during operation. The present invention relates to an overflow prevention control system for a continuous operation condensate pump.
[0002]
[Prior art]
The conventional technology will be described for the condensate water supply system of the thermal power plant shown in FIG. The steam that contributes to power generation in the steam turbine 2 is heat-exchanged with the seawater 20 in the condenser 7, and then condensed and temporarily stored in the condenser 7.
[0003]
The condensed water (condensate) temporarily stored in the condenser 7 is extracted by the condensate pump 8 and heated by the feed water heater 9, and then the deaerator 11 through the deaerator water level control valve 10. Flow into.
[0004]
The condensed water flowing into the deaerator 11 is extracted by the boiler feed water pump 12 and heated by the feed water heater 13 and then supplied to the boiler 1.
[0005]
The condenser 7 prevents the heat exchange between the seawater 20 and the steam turbine exhaust steam 5 from being lowered due to the rise in the stored water level. When the condenser 7 water level rises above a certain value, the condenser spillover valve A condenser high water level control device 30 that lowers the condenser water level by controlling 31 to open is installed.
[0006]
[Problems to be solved by the invention]
In normal plant operation, when two condensate pumps 8 in FIG. 1 are operating and one of them is tripped, the amount of extraction from the condenser 7 decreases, so the water level of the condenser 7 rises.
[0007]
When the water level of the condenser 7 rises above the specified water level, the condenser spillover valve 31 of the condenser high water level control device 30 that discharges the condensed water from the outlet of the condensing pump 8 to the outside of the system is opened.
[0008]
When the condenser spillover valve 31 is opened, the outflow amount of the condensate pump 8 is increased, so that the condensate pump 8 enters an excessive flow rate state.
[0009]
The condensate pump 8 that has reached an excessive flow rate is tripped because operation cannot be continued due to overload.
[0010]
When the second condensate pump 8 trips, it becomes impossible to supply water to the boiler 1, which causes a problem of stopping the plant.
[0011]
The object of the present invention is to prevent the condensate pump from having an excessive flow rate.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, the present invention operates the condenser high water level control device for a certain period of time even if two condenser pumps trip and one of the condenser pumps trips and the condenser water level temporarily rises. In other words, a control device that does not open the condenser spillover valve 31 is installed.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
An example in which the present invention is applied to a condensate system of a thermal power plant will be described with reference to FIG.
[0014]
The condensate stored in the condenser 40 is extracted by the condensate pump 41 and the condensate pump 42, heated by the feed water heater 43, and then deaerator through the deaerator water level control valve 44. 45.
[0015]
Condensate in the deaerator 45 is extracted by the boiler feed water pump 46, heated by the feed water heater 47, and then fed to the boiler 49 via the feed water adjustment valve 48.
[0016]
FIG. 3 shows the condenser water level, turbine load, condensate pump 41 flow rate, and condensate pump 42 flow rate when the condensate pump 42 trips.
[0017]
The turbine load 60 is operated at a load of 100%, and the two condensate pumps are a condensate pump 41 normal flow rate 64 and a condensate pump 42 normal flow rate 65, which are 140 t / h, respectively.
[0018]
In this state, the condensate pump 41 trips.
[0019]
When one of the condensate pumps in operation is tripped, the condensate pump 42 that has been in operation since the condensate pump 421 covers the amount of water passing through the two condensate pumps. The water pump overflow limit flow rate 67 exceeds 210 t / h and increases to 232 t / h, resulting in an overflow state.
[0020]
As a preventive measure, this plant performs control to lower the turbine load 60 to 50% load and reduce the water flow rate of the condensate pump that continues to operate.
[0021]
However, since the condensate pump 42 that continues to operate while lowering the load from 100% load to 50% load becomes overflow, the deaerator water level control valve opening is set to the condensate pump overflow limit flow rate. At the same time as the condensate pump 41 trip, it is narrowed down to an opening degree equivalent to 193 t / h below 67.
[0022]
In that case, since one of the condensate pumps trips during operation, the amount of water extracted from the condenser temporarily decreases, and the water level of the condenser rises.
[0023]
Since the condenser water level rises to the condenser high water level control device operation setting water level 63, the condenser high water level control device operates, opens the condenser spillover valve 51, and discharges the condensate outside the system.
[0024]
When the condenser spillover valve 51 is opened and the condensate is discharged out of the system, the flow rate of the drainage condensate pump 42 is 232 t / of the condensate pump flow rate 66 when the condenser high water level controller is activated. Increase to h.
[0025]
Therefore, when one of the condensate pumps trips and the load drops, even if the condenser water level exceeds the specified water level, the condenser high water level controller is not operated for a certain period of time. The spillover valve is not opened.
[0026]
FIG. 4 shows an interlock for preventing the condenser high water level control device from operating when one condenser pump trips during operation.
[0027]
When the condensate pump 41 stop signal 80 or the condensate pump 42 stop signal 81 is generated, the condenser spillover valve 83 is forcibly closed for 45 minutes when the timer 84 operates.
[0028]
【The invention's effect】
According to the present invention, the condenser high water level control device is configured so that when one condenser pump trips when one unit is operated, the condenser high water level rises to the specified value even when the condenser water level rises to a specified value. By not operating the control device for a certain period of time, it is possible to prevent the condenser spillover valve from being opened and the condensate pump that is operating continuously being overloaded.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a conventional technique.
FIG. 2 is a diagram illustrating the present invention.
FIG. 3 is a diagram illustrating the present invention.
FIG. 4 is a diagram illustrating the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Boiler, 2 ... Steam turbine, 5 ... Steam turbine exhaust steam, 6 ... Generator, 7 ... Condenser, 8 ... Condensate pump, 9 ... Feed water heater, 10 ... Deaerator water level control valve, 11 ... Deaerator, 12 ... Boiler feed pump, 13 ... Feed water heater, 14 ... Feed water control valve, 20 ... Sea water, 30 ... Condenser water level control system, 31 ... Condenser spillover valve, 40 ... Condenser, 41 ... Condensate pump, 42 ... Condensate pump, 43 ... Feed water heater, 44 ... Deaerator water level control valve, 45 ... Deaerator, 46 ... Boiler feed pump, 47 ... Feed water heater, 48 ... Feed water control valve, 49 ... Boiler, 50 ... Condenser high water level control device, 51 ... Condenser spillover valve, 52 ... Condensate pump stop signal, 53 ... Condenser water level signal, 54 ... Deaerator water level control valve opening limit signal 55 ... Condenser spillover valve opening limit signal, 56 ... Calculation unit, 60 ... Turbine load 61: Condenser normal water level, 62: Condenser maximum water level, 63: Condenser high water level control device operation set value, 64: Condensate pump 41 normal water flow, 65 ... Condensate pump 42 normal water flow, 66 ... Condensate pump flow rate when the condenser high water level control device is operating, 67 ... Condensate pump overflow limit flow rate, 68 ... Condensate pump water flow rate when the condenser high water level control device is not operating, 80 ... Condensate Pump 41 stop signal, 81 ... condensate pump 42 stop signal, 82 ... condenser spillover valve, 83 ... timer.

Claims (1)

In a condensate pump control system for a power plant that has an external discharge valve that discharges condensate outside the system when the condensate pump is composed of multiple units and the water level in the condenser becomes high, the condensate pump is A condensate pump control system characterized in that when one unit trips during operation of all units, the outside discharge valve is forcibly fully closed temporarily.

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