JPS63315803A - Feedwater-heater drain controller - Google Patents

Abstract

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

Description

[Detailed description of the invention]

(Objective of the Invention) (Industrial Application Field) The present invention provides an method for controlling the flow 16 when injecting condensate discharged from a feedwater heater of a steam turbine plant into a condensate water supply system.

[Enter the feed water heater drain control device.] (Prior Art) Generally, a steam turbine plant consists of a main steam system that connects a steam generator and a turbine, and a condensate system that connects a turbine condenser, a condensate pump, a low-pressure feedwater heater for condensate heating, and a feedwater pump. And this water pump, i! The configuration is such that the water supply system connecting the 11 water supply heating and steam valve 2 is arranged on the right. Conventionally, such natural air turbine plants have been described above. ! '! A feedwater heater drain system is provided for injecting condensate discharged from the l-pressure feedwater heater into the low-pressure feedwater heater and injecting condensate discharged from the low-pressure feedwater heater into the condenser. This feedwater heater drain system is provided with a flow rate control valve that adjusts the drain flow chamber, and by adjusting the drain flow rate with this flow rate control valve, water level control is performed to keep the water level of the feedwater heater or drain tank constant. It has become. On the other hand, in recent steam turbine plants, improvements have been made to feedwater heater drain systems in order to improve plant efficiency or reduce condensate anchorage. , collecting and accumulating it in a drain tank, increasing the pressure of this drain using a drain pump, and injecting it into the condensate system. In this system, multiple regular drain pumps are installed in parallel, and one flow 1d control valve is connected to the header line that connects the outlet of the drain pump. Not set up. However, if the drain pump trips for some reason and the number of drain pumps in operation decreases, the total suction flow rate of the drain pump decreases. As a result, the water level in the drain tank rises rapidly, the control valve is advised to open, the flow Iδ increases, and the drain pump in operation may become overflow and trip, causing the drain pump to stop altogether. . (Problems to be Solved by the Invention) In the conventional feed water heater drain control device 611, when one of the drain pumps arranged in parallel trips, the other drain pumps in operation also trip. All drain pumps may stop. This causes a problem in that one large disturbance occurs in which the condensate flow rate suddenly decreases. The present invention has been made in view of the above circumstances, and in recovering the drain from the feed water heater to the condensate system, even if some of the drain pumps trip, other operating drain pumps are It is an object of the present invention to provide a feed water heater drain control device that can prevent a drain pump from tripping, thereby minimizing disturbances such as a decrease in condensate flow rate. [Structure of the Invention] (Means for Solving the Problems) The present invention provides for drain discharged from a feedwater heater of a steam turbine plant to be transferred from a storage drain tank to a plurality of drain pumps arranged in parallel, an outlet header, and a flow rate. For water injected into the condensate system via a control valve, the difference between the water level detector that detects the drain water level in the drain tank and the water level detection signal output from this water level detector and the set water level signal. an opening setting device that outputs a maximum permissible opening signal of the flow control valve according to the number of drain pumps in operation; Low 1ii'If inputs a signal and outputs a valve command signal corresponding to the lowest value of the number of drain pumps in operation among the allowable maximum opening signals to the 1111 control valve.
! It is characterized by being formed by combining the previous circuit. (Operation) Suppose some of the drain pumps trip for some reason. In that case, the total suction flow rate decreases, causing the water level in the drain tank to rise rapidly. Then, the drain tank water level signal and the water level deviation signal increase, and the open 1α request signal rises rapidly, but the maximum allowable opening signal for the remaining units in operation is newly input to the low value forwarding circuit. Therefore, the flow rate of the drain pumps in operation is limited to 4 or less, which corresponds to the number of remaining operating drain pumps. Therefore, even if some of the drain pumps trip, other drain pumps in operation will be prevented from overflowing and tripping, and will be able to continue operating at the maximum allowable flow ω or higher, which will reduce the flow rate of salt water. This disturbance can be suppressed to a minimum. (Example) An example of the present invention will be described above with reference to the drawings. First, the entire steam turbine plant will be schematically explained with reference to FIG. A high-pressure turbine 3 and a low-pressure turbine 4 are connected to a nuclear reactor 1 as a hot air generator via a main steam pipe 2, thereby forming a main natural gas system 5. A condensate pump 8, a low-pressure feed water heater 9, and a reactor feed water pump 10 are connected to a condenser 6 provided in the low pressure turbine 4 via a condensate pipe 7, thereby forming a condensate system 11. . Further, the reactor feed water pump 10 is connected to a high pressure feed water heater 13 and the nuclear reactor 1 via a water supply pipe 12, thereby forming a water supply system 14. Then, a feed water heater drain tank 16 is connected to the high pressure feed water heater 13 via a drain pipe 15, and further connected to the drain tank 16 via a branch pipe 17. ! While connecting the 2r/i drain pumps 18a, 18b...
A flow rate 1!1 regulating valve 20 is connected to each of the drain pumps 18a, 18b via a header pipe 19, a condensate pipe 7 is connected to this flow ht regulating valve 20 via a water injection pipe 21, and the J: This constitutes a feed water heater drain system 22. Next, the feed water heater drain control device will be explained with reference to FIGS. 1 and 2. As shown in FIG. 1, a water level detector 2 is installed in the drain tank 16.
4, and the water level detection signal 101 is outputted to the control device 25. In addition, the drain pumps 18a, 1
Drain pump operating number detector 2 to determine the operating number of 8b
6, and from this, control m+equipment'? A drain pump operating number signal 102 is output at t25. The control device 25 then sends an IQ command signal 103 based on the water level detection signal 101 and the drain pump operation number signal 102.
is output to the flow control valve 20. As shown in FIG. 2, the control device 25 includes a water level setting device 27.
7111 t'i device 28, pH') function 0 circuit 29, opening degree setting device 30, switch circuit 31 and low (1^ priority circuit 32) are connected.Drain tank water level detection signal from the water level detector 24 mentioned above 101 and the drain tank water level setting signal 104 from the water level setting device 27 are compared by the adder 28. Then, according to the water level deviation signal 105 which is the result of this comparison, P
The IDll#ti circuit 29 generates an opening request signal 10 for setting the drain flow rate to keep the drain tank water level constant.
6 is output to the low value priority circuit 32. On the other hand, the drain pump operation number detector 26 outputs one unit operation signals 102a and 2 as drain tank operation number signals.
The unit operation signals 102b..., n unit operation signals 102n are selectively output. Then, in response to this, each contact 31a, 31b, . 107a, maximum allowable opening signal when operating two units 107b..., maximum allowable opening signal when operating n units 1
07n is output to the low value priority circuit 32. In the low value priority circuit 32, opening signals 107a, 107b, 307
The valve opening corresponding to the smallest number of operating units is selected from among n, and the corresponding opening command signal 103 is sent to the flow rate control valve 20.
is output to. Next, the effect will be explained. Now, for example, there are two regularly used drain pumps 18a. 18 b /J<Consider the installed equipment. It is assumed that both drain pumps 18a and 18b are normally operated. In this case, the low value priority circuit 32 has
The maximum allowable opening signal 107b when operating two units and the opening request signal 106 from the PID performance circuit 29 are input, and the lowest value of both signals is selected and the opening command signal 103 is output. . Suppose that one of the drain pumps 18a trips for some reason in this state. In case A, the water level in the drain tank 16 decreases by decreasing the total suction flow rate.
Up? Do J. Then, the drain tank water level signal 101 and the water level deviation signal 105 increase, and the opening request signal 106 is changed. By newly inputting the I river signal 107a, the flow rate of the drain pump 18b during operation is limited to the allowable maximum flow ill or F for one unit. Therefore, even if one of the drain pumps trips, the other drain pumps that are in operation will still be affected by the excess flow rate.
Lipping is prevented, and operation can be continued below the maximum flow rate, thereby minimizing the disturbance of the condensate flow 11. Note that in the above embodiment, the drain pump Although the effect in the case of two drain pumps has been explained, it goes without saying that the same effect can be obtained even if a larger number of drain pumps are used.Furthermore, in the above embodiment, an atomic couplant was used as an example, but thermal power It goes without saying that the same can be implemented in plants, etc. [Effects of the Invention] As described above, according to the present invention, in the feed water heater drain system that collects drain discharged from the feed water heater to the condensate system, Even if some of the plurality of drain pumps trip, the allowable maximum capacity (i) corresponding to the number of remaining drain pumps is selected, and the capacity of the flow control valve is determined accordingly. Therefore, it is possible to minimize the disturbance of a decrease in the flow rate of condensate when the drain pump trips.

[Brief explanation of drawings]

Fig. 1 is a system configuration diagram showing one embodiment of the present invention, and Fig. 2 shows the control shown in Fig. 1! A block diagram showing the II device section in detail, and FIG. 3 is a system diagram showing an example of the configuration of a steam turbine to which the control neck making section of FIG. 1 is applied. 13... (High pressure) feed water heater, 16... Drain tank, 18a, 18b... Drain pump, 20... Flow control valve, 24... Water level detection, 29... Calculation Circuit, 30...Opening degree setting device, 32...Low value priority circuit. Applicant's agent Hisashi Hatano Figure 1 Figure 2

Claims (1)

[Claims] In a system in which drain discharged from a feed water heater of a steam turbine plant is injected from a storage drain tank into a condensate system via a plurality of drain pumps arranged in parallel, an outlet header, and a flow rate control valve, a water level detector that detects the drain water level; a calculation circuit that calculates the difference between the water level detection signal output from the water level detector and a set water level signal and outputs a water level deviation signal; and the flow rate adjustment according to the number of operating drain pumps. An opening setting device that outputs the maximum allowable opening signal of the valve, and a valve that receives the water level deviation signal and the maximum allowable opening signal and corresponds to the lowest value of the number of drain pumps in operation among the maximum allowable opening signals. A feed water heater drain control device comprising: a low value priority circuit that outputs an opening command signal to the control valve.