JPH07110106A - Chemical feeder in steam-powder plant - Google Patents

Abstract

PURPOSE:To reduce magnetite adhering to the impeller of a feedwater pump by connecting chemical-feeding tanks respectively to the outlet of a condensate pump and that of a feedwater pump with a pump interposed in each connection in a setup to control each of the interposed pumps on the basis of signals representing the concentration of the chemical in the condensate and feedwater respectively and signals representing set values. CONSTITUTION:A steam-power plant consists of a system connecting by conduits a steam generator 1, turbine 3, condenser 4, condensate pump, feedwater heater, deaerator 8, feedwater pump 10, and feedwater heater 11. A first chemical- feeding tank 12 is connected to the conduit on the outlet side of the condensate pump 5 with a pump 13 interposed therebetween. This pump 13 is controlled by a controller 16 according to the output of a chemical-concentration detector 15. A second chemical-feeding tank 18 is connected to the conduit on the outlet side of the feedwater pump 10 with a pump 19 interposed therebetween. The pump 19 is controlled by a controller 22 according to the output of a chemical- concentration detector 21. The controllers 16, 22 respectively output control signals 25, 26 according to the respective detection values of the chemical concentration and signals representing respective set values in a setting unit 24.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chemical injection device for a steam power plant applied to a nuclear power plant, a thermal power plant or the like.

[0002]

2. Description of the Related Art In a nuclear or thermal power plant to which a chemical injection device is applied, as shown in FIG.
Turbine 3, condenser 4, condensate pump 5, water heater 7,
A loop is formed by the deaerator 8, the water supply pump 10, and the water supply heater 11.

In the above, the steam 2 from the steam generator 1
Becomes water in the condenser 4 after working on the turbine 3, and this water is sent as condensate 6 by the condensate pump 5 to the deaerator 8 via the water supply heater 7 and then as water 8 by the water supply pump 10. It is returned to the steam generator 1 via the water heater 11.

As shown in FIG. 1, the conventional chemical injection device applied to the above-mentioned power plant is a chemical injection tank 12 and a pump 1.
3, a conduit 14, a detector 15, and a controller 16, and a chemical (hydrazine, etc.) stored in the chemical injection tank 12 is pumped by the pump 13 via the conduit 14 to the outlet of the condensate pump 5. Had been injected into.

The chemical injection amount is controlled by the detector 15 which detects the chemical concentration in the condensate 6 and outputs the output signal from the controller 16 to control the chemical injection amount of the pump 13. It was set to a predetermined value.

Generally, hematite (Fe ₂ O ₃ ) is contained in the condensate 6.
Is contained in a relatively large amount, but in order to prevent this from flowing into the steam generator 1, hematite is reduced to produce magnetite (F
Chemicals are injected for the purpose of changing to e ₃ O ₄ ). Therefore, the hematite contained in the condensate 6 on the downstream side of the condensate pump 5 is reduced to magnetite, and this magnetite is contained in the water supply 9 from the deaerator 8 to the water supply pump 10.

[0007]

In the conventional device, the chemical was injected into the pipe between the condensate pump and the water heater as described above, but the chemical is injected into the water supply. There is a problem that magnetite adheres to the impeller of the water supply pump and hinders the operation of the pump.
The present invention is intended to solve the above problems.

[0008]

A chemical injection device for a steam power plant according to the present invention comprises a steam generator, a turbine, a condenser, a condensate pump, a first feed water heater, a deaerator, a feed water pump, and a first feed water heater. In a steam power plant in which two water supply heaters are sequentially connected to form a loop, a first chemical injection tank connected to the outlet side pipe line of the condensate pump via a first pump, and the water supply pump Concentration of chemicals in the condensate from the second chemical injection tank connected to the outlet side pipeline via the second pump, the first detector provided in the outlet side pipeline of the first water heater A first controller for inputting a signal to control the first pump, and a concentration signal of the chemical in the feed water from a second detector provided in the outlet side pipe line of the second feed heater are input. A second controller for controlling the second pump, and the first and second water supply heaters. Formed by a setter that outputs first and second setpoint signals representing the setpoints of the chemical concentrations in the condensate and feedwater in the outlet side pipe of the controller and inputs them to the first and second controllers, respectively. It is characterized by being done.

[0009]

In the above, the first set value signal output from the setter to the first controller has an amount commensurate with a slight amount of dissolved oxygen contained in the condensate in the outlet side pipe of the first feed water heater. Indicates the chemical concentration when the chemical is injected into condensate,
This is the set value signal for the chemical concentration in the condensate.

Further, the second set value signal output from the setter to the second controller indicates that the amount of the predetermined chemical required by the plant corresponds to the amount of dissolved oxygen contained in the condensate. It represents the chemical concentration when the amount subtracted is injected into the water supply, which is the set value signal of the chemical concentration in the water supply.

When the first controller inputs the first set value signal and the concentration signal of the chemical in the condensate, the first controller sets the concentration of the chemical in the condensate in the outlet pipe of the first water heater. The first pump is controlled to adjust the injection amount of the chemical from the first chemical dosing tank so as to obtain the value.

Further, when the second controller inputs the second set value signal and the concentration signal of the chemical in the feed water, the concentration of the chemical in the feed water in the outlet side conduit of the second water heater is input to the second controller. The second pump is controlled to adjust the injection amount of the chemical from the second chemical injection tank so that the value becomes a set value.

Due to the above, the chemical concentration in the condensate decreases,
Since water is supplied to the feed pump in a state where there is almost no magnetite in the condensate, the adhesion of magnetite to the impeller of the feed pump is extremely reduced, and good operation of the feed pump can be continued.

[0014]

FIG. 1 shows a chemical injection device according to an embodiment of the present invention. In this embodiment shown in FIG. 1, a steam generator 1, a turbine 3, a condenser 4, a condensate pump 5, a water supply heater 7, a deaerator 8, a water supply pump 10, and a water supply heater 11 are sequentially connected by a pipeline. In the steam power plant in which the loop is formed, the first chemical injection tank 12 connected to the outlet side pipeline of the condensate pump 5 via the pipeline 14 and the pump 13, the outlet side pipeline of the water supply heater 7. Is connected to a controller 16 for inputting a signal from a detector 15 connected to and a signal 17 output from the detector 15 to the pump 13, an outlet side pipeline of the water supply pump 10 through a pipeline 20 and a pump 19. The second chemical injection tank 18 and the signal 21 output from the detector 21 connected to the outlet side pipe of the water heater 11
A controller 22 for inputting 3 to the pump 19 and a setter 24 for inputting signals 25 and 26 to the controllers 16 and 22, respectively are provided.

In the above, the detectors 15 and 21 detect the chemical concentration in the condensate 6 or the feed water 9, respectively, and input the output signals to the controllers 16 and 22, respectively. A signal 2 output from the setter 24 is further supplied to these controllers 16 and 22.
5, 26 are input respectively.

Signals 25 and 26 output from the setter 24
Is the amount of chemicals corresponding to the slight amount of dissolved oxygen contained in the condensate in the outlet side of the condensate pump, and the amount of this chemical subtracted from the amount of the prescribed chemical required by the plant, The respective chemical concentrations are shown when they are injected into the condensate 6 and the feed water 9, respectively, and are set value signals of the chemical concentration.

The controllers 16 and 22 to which the set value signals 25 and 26 of the chemical concentration and the signals 17 and 23 are respectively inputted,
The pumps 13 and 19 are controlled so that the chemical concentrations of the condensate 6 and the feed water 9 on the outlet side of the water heaters 7 and 11 become the set values of the chemical concentrations indicated by the signals 25 and 26, respectively.

Therefore, it becomes possible to reduce the amount of chemicals injected from the pipe line 14 as compared with the conventional case, and to inject the reduced amount from the pipe line 20. As a result, the chemical concentration in the condensate 6 becomes low. , Hematite in the condensate 6 is hardly reduced, that is, when magnetite is almost absent, it becomes the feed water 9 and flows into the feed pump 10. Therefore, the adhesion of magnetite to the impeller of the feed pump 10 becomes extremely small. The operation of the water supply pump 10 can be continued in good condition.

[0019]

The chemical injection device of the steam power plant of the present invention has the first and second chemical injection tanks in the outlet side conduits of the condensate pump and the feed water pump via the first and second pumps, respectively. Concentration signals of chemicals in the condensate and feed water from the first and second detectors connected to the outlet side pipes of the first and second water feed heaters respectively, and the first and second signals from the setter. By controlling the first and second pumps by the first and second controllers respectively inputting the second set value signals, the chemical concentration in the condensate is reduced, and magnetite is almost present in the condensate. Since water is supplied and flows into the water supply pump in a state where the water is not supplied, the adhesion of magnetite to the impeller of the water supply pump is extremely reduced, and the water supply pump can be operated well and reliability is improved.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a chemical injection device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a conventional device.

[Explanation of symbols]

 1 Steam Generator 3 Turbine 4 Condenser 5 Condensate Pump 7 Water Supply Heater 8 Deaerator 10 Water Supply Pump 11 Water Supply Heater 12 Chemical Injection Tank 13 Pump 14 Pipeline 15 Detector 16 Controller 18 Chemical Injection Tank 19 Pump 20 Tube Road 21 Detector 22 Controller 24 Setting device

Claims (1)

[Claims] 1. A steam power system in which a steam generator, a turbine, a condenser, a condensate pump, a first water heater, a deaerator, a water pump, and a second water heater are sequentially connected to form a loop. In the plant, a first chemical injection tank connected to the outlet side pipeline of the condensate pump via a first pump,
Condensed water from the second chemical injection tank connected to the outlet side conduit of the water supply pump via the second pump, and the first detector provided in the outlet side conduit of the first water heater. Concentration of the chemical in the feed water from the first controller for controlling the first pump by inputting the concentration signal of the chemical of the above, and the second detector provided in the outlet side pipeline of the second water heater. A second controller for inputting a signal to control the second pump; and the first controller
And 1st and 2nd set value signals representing set values of the chemical concentration in the condensate in the outlet side pipe of the 2nd feed water heater and the feed water are output and input to the 1st and 2nd controllers, respectively. And a chemical injector for a steam power plant.