JPS63140288A - Vane opening controller for circulating water pump - Google Patents

Abstract

PURPOSE:To enable the temperature at an outlet of a condenser to be controlled to within a limited range without deteriorating the degree of vacuum in the condenser, by setting a circulating water pump vane opening according to a turbine load in a normal operation, and when the a cutback (FCB) occurs, holding the circulating water pump vane opening at the value before the FCB. CONSTITUTION:A circulating water pump 5 is equipped with a vane opening varying device, and sea water or river water taken in by the pump is supplied to a condenser 4 through an outlet valve 6, a circulating water pipe 7 and a condenser inlet valve 8. The load on a generator 12 driven by a steam turbine 3 is detected by a turbine load detector 13, and the detected load signal S13 and a vane opening signal S14 detected by a circulating water pump opening detector 14 are subjected to comparison and calculations in a comparing calculator 14 to calculate a circulating water pump vane opening according to the load, and the vane opening thus calculated is sent to the vane opening varying device 15 to set the vane opening. When the a cutback (FCB) occurs, the signal from the calculator 14 is cut off by a switching device 16 for a circulating water pump vane opening command, thereby holding the vane opening of the pump at the value before the FCB.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] ′ (Industrial Application Field) The present invention relates to a blade opening control device for a circulating water pump to which a circulating water pump blade opening variable device is attached.

(Prior art) In general, the circulating water system in a thermal power plant or a thermal power plant cools the exhaust gas flowing from the steam turbine to the condenser.
It is systematized to take seawater or river water and send it to a condenser using a circulating water pump.

The circulating water pump installed in this circulating water system.

Fixed-blade pumps used to have a fixed blade opening, but in recent years movable-blade pumps have been adopted from the perspective of energy conservation, which can pump a circulating water volume commensurate with the turbine load. This movable vane type circulating water pump calculates the circulation M corresponding to the turbine load in advance, detects the turbine load, and calculates the actual load and the circulating water pump blade opening corresponding to the load using a ratio V calculator. The circulating water pump is controlled so that the opening degree is determined.

(Problems to be Solved by the Invention) However, with this circulating water pump control method, the turbine load is reduced during FCB (first cutback), but when the amount of steam flowing into the condenser is large,
In other words, if the turbine load and the amount of heat flowing into the condenser do not match, the degree of opening of the circulating water pump will become smaller, and the amount of circulating water sent to the condenser will decrease, so the degree of vacuum in the condenser will deteriorate. The temperature in the turbine exhaust chamber increases, causing a thermal effect on the final stage blades of the turbine, and there is a risk that the condenser rubber expansion may also be deformed due to the thermal effect. Furthermore, there is a possibility that the condenser is operated with a temperature difference between the seawater inlet and outlet exceeding a limit value, for example, 7°C.

SUMMARY OF THE INVENTION An object of the present invention is to provide an opening control device for a circulating water pump that does not rapidly change the degree of vacuum in a condenser and the temperature difference between the seawater inlet and outlet of the condenser even during FCB.

[Structure of the invention]

(Means and effects for solving the problem) The opening degree control device for a circulating water pump according to the present invention is a device for controlling the degree of opening of a circulating water pump in a thermal or nuclear power plant by passing seawater or river water to a condenser using a circulating water pump to generate a steam turbine. In a circulating water system that cools the exhaust air from the air and then releases water back into the sea or river, a variable circulating water pump blade opening is used to change the circulating water pump blade opening so that any amount of circulating water can be supplied to the municipal circulating water pump. The device is attached, and further includes a comparison calculator that outputs a circulating water pump blade opening command by comparing the detected turbine load and circulating water pump blade opening with the set opening of the circulating water pump blade opening. A circulating water pump blade opening degree variable device that sets the circulating water pump blade opening degree using a signal from a comparator, and an FC
The apparatus is characterized by comprising a circulating water pump 'R opening command switching device that cancels the circulating water pump blade opening setting signal upon receiving the B signal and holds the circulating water pump blade opening at the circulating water pump blade opening before the occurrence of FCB. It is.

In the present invention, during normal operation, the opening degree of the circulating water pump blades is set to match the turbine load, and at F'C8, the opening degree of the circulating water pump is controlled to be held at the opening degree before FCB. Therefore, even during FCB, the degree of vacuum in the condenser and the temperature difference between the inlet and outlet of seawater in the condenser do not change suddenly.

(Example) An example of the present invention shown in the drawings will be described below. 1st
In the figure, steam generated from a steam generator 1 such as a boiler is sent to a steam turbine 3 through a main steam stop valve and a control valve 2, and after working at the knee, is sent to a condensate rj 14 and is converted into condensate water. A generator 12 driven by a steam turbine 3 generates electrical power.

On the other hand, the circulating water pump 5.5 is equipped with a variable opening device, and the seawater or river water taken in by this pump is transferred to the circulating water pump outlet valves 6, 6. Circulating water pipe 7 and condenser inlet valve 8
．． 8 and is supplied to the condenser 4. This condenser 4 condenses the exhaust gas of the steam turbine 3, raises the temperature, and discharges the condensate through the condenser outlet valve 9°9 and the circulating wood pipe lO.
sent to.

Next, the characteristics of the circulating water pump 5 will be explained with reference to FIG. Each load A, B, C of the steam turbine 3.

Circulating water pump blade opening degree commensurate with D a T b l C
It shows ld. These opening degrees a, b, c, and d correspond to the vacuum degree of the condenser 4 at the rated vacuum degree (normally 722 mn Hg
VAC) and the temperature difference between the inlet and outlet of the condenser is, for example, 7° C., and the required amount of circulating water is determined from the intersection with the system head curve 1iH of the circulating water system. The relationship between the 'R opening degrees a, b, c, d of the circulating water pump 5 found in FIG. 2 and the turbine loads A, B, C, D is expressed as shown in FIG. It is programmed into the device and controls the degree of opening of the circulating water pump 5.

Furthermore, in FIG. 1, a generator 12 driven by a steam turbine 3 generates electric power, but the load at that time is detected by a turbine load detector 13, and the degree of opening of the circulating water pump 5 is determined by the opening of the circulating water pump blades. be detected by the detector 14. The wj circulating water pump blade opening command set based on the detected load and opening degree is transmitted to the circulating water pump blade opening degree variable device 15.15, and the opening degree is controlled as shown in Fig. 4. .

The actual control method at this time will be explained with reference to Fig. 5.
Comparison calculation is performed in a comparator 14 using the load signal S13 detected by the turbine load detector 13 in FIG. 1 and the blade spacing signal S,4 detected by the circulating water pump spacing detector 14,
Calculate the circulating water pump blade opening commensurate with the turbine load,
The number 44 is sent to the FR ring water pump blade inter-blade variable device V115 to set the inter-blade distance.

Furthermore, when FCB occurs, the FCB signal shown in FIG. Turn off the circulating water pump blade opening degree to P.
The opening will be maintained at the opening before CB. Thus F.C.B.
Even at times, the temperature at the inlet and outlet of the condenser can be maintained within a controlled value, for example, 7° C., without deteriorating the degree of vacuum in the condenser 4.

〔Effect of the invention〕

As described above, in the present invention, during normal operation, the circulating water pump blade opening is set to match the turbine load, and during FCB, the circulating water pump blade opening is held at the opening before FCB. As a result, even during FCB, the degree of vacuum in the condenser is not deteriorated, and the temperature at the condenser outlet can be kept within the limit value.

[Brief explanation of the drawing]

Fig. 1 is a system diagram showing an embodiment of the circulating water pump blade spacing control device according to the present invention, Fig. 2 is a system head curve diagram of the circulating water pump, and Fig. 3 is a diagram showing the turbine load and circulating water pump blade opening. FIG. 4 is a control block diagram for setting the circulating water pump blade opening degree corresponding to the turbine load. FIG. 5 is a control block diagram for implementing the control means attached to the present invention. It is. 1... Steam generator (boiler) 3... Steam turbine 4... Condenser 5... Circulating water pump 11... Discharge channel 12... Generator
13...Turbine load detector 14...Circulating water pump blade gap J (detector 15...Circulating water pump blade opening variable device 16...Turbine bypass valve 17...Desuperheater 1
&+ Fig. 1 g, ψ (%) ◆ Brown Fig. 2 Turbin Pejki (%) → $ 3 Fig. 4 Concave grass 5 Fig.

Claims (1)

[Claims] (1) In a circulating water system in a thermal or nuclear power plant where seawater or river water is passed through a condenser using a circulating water pump to cool the exhaust from a steam turbine and then released into the sea or river again, the circulating water is A circulating water pump blade opening variable device that changes the circulating water pump blade opening is attached so that any amount of circulating water can be supplied to the pump, and the turbine load, circulating water pump blade opening, and circulating water pump blade are also adjusted. Comparison calculator that outputs a circulating water pump blade opening command by comparing the opening setting with the blade opening, and a circulating water pump blade opening that sets the circulating water pump blade opening with the signal from the comparison calculator. Equipped with a variable device and a circulating water pump blade opening command switching device that receives the FCB signal at the time of FCB and cancels the circulating water pump blade opening setting signal and holds the circulating water pump blade opening at the circulating water pump blade opening before the occurrence of FCB. A blade opening control device for a circulating water pump featuring: