JPS5819605A - Controller for flow rate of circulation of feedwater for economizer - 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 The present invention relates to a feed water circulation flow rate control device for a energy saver, and more particularly to a feed water circulation flow rate control device for a energy saver in a waste heat recovery boiler in a combined plant of a gas turbine and a steam turbine.

This type of combined plant is mainly used as an intermediate-load power generation plant, and therefore the boiler is started and stopped frequently.
When starting up again after stopping (for about s hours) (hot start), the water in the economizer has risen to nearly the saturation temperature from the previous start, so when gas flow to the waste heat recovery boiler starts, A steaming phenomenon occurs within the economizer, and various syllables are generated.

Therefore, in the past, an operator manually operated a controller to control the circulating flow rate of water to the economizer while monitoring the water supply temperature at the economizer outlet to prevent it from reaching the steeping range. The system adjusts the system in response to changes in the water supply temperature, and switches to automatic control when the gas turbine load increases to a certain extent.

If the water supply circulation flow rate controller is set to automatic control from the beginning, the water in the economizer will rise to near the saturation temperature at the time of a hot start, as mentioned above, and will reach the saturation range immediately after the life gas. This is automatically detected and the water circulation flow rate of the energy saver increases rapidly, followed by a temperature drop immediately after that, which causes a hunting phenomenon in which the water circulation flow rate suddenly decreases, which is not favorable from the viewpoint of control stability. tL, <No〇 As mentioned above, in the conventional control system, the operator must manually operate the controller at the time of hot start, and if monitoring is neglected, a steaming phenomenon will occur in the economizer.

The purpose of the present invention is to eliminate the drawbacks of the prior art as described above, to automatically control the water supply circulation flow rate to the economizer from the point of gas passing through the waste heat recovery boiler, and to provide a stable water supply that does not cause the hunting phenomenon. An object of the present invention is to provide a water supply circulation flow rate control device for an energy saver in which circulation is performed.

In order to achieve this object, the present invention includes a water supply temperature detection means for detecting the temperature of the water supply at the outlet of the energy saver, and a water supply temperature detection means for detecting the temperature of the water supply at the outlet of the energy saver, and a water supply temperature detection means for adjusting the circulating flow rate of the water supply of the energy conservation device based on a detection signal from the water supply temperature detection means. A circulating flow rate adjusting means, a pre-supply water circulation means for allowing a predetermined amount of water to flow through the economizer for a predetermined time from the start of gas flow to the economizer, and detecting the temperature of the feed water after the supply water circulation by the pre-supply water circulation means. and a control switching means for switching to control of the water supply circulation flow rate by the water supply circulation flow TAX means. Since the temperature of the water supply can be detected, the control of the flow rate of the water supply** is stable, and automatic control is possible from the point of gas flow.

Next, embodiments of the present invention will be described with reference to the drawings. Figure 1 shows
This is an outline of W factors of a waste heat recovery boiler in a combined plant of a gas turbine and a steam turbine.

Exhaust gas 1 from a gas turbine (not shown) sequentially passes through a superheater 2, an evaporator 39, and a carbon-saving device 4 of a waste heat recovery boiler to recover its retained heat, and the steam generated in the superheater 2 is transferred to the turbine. It passes through a control valve 5 and is supplied to a steam turbine (not shown).

On the other hand, the condensate 6 discharged from the steam turbine is transferred to the deaerator 7.
Deaerator tank8. Water pump9. Feed water heater 10. The water is sent to the economizer 4 through the water supply flow rate adjustment valve 11 and heated by the economizer 4, and then supplied to the drum 12.

The water supply circulation flow rate of the economizer 4 is adjusted by a economizer circulation flow rate adjustment valve 13 connected to the water supply pipe between the economizer 4 and the drum 12, and a circulation flow meter 14 is attached to it. . 15 is a water supply temperature detector attached to the outlet side of the economizer 4, 16 is a drum pressure detector, 17 is a drum water level detector, and 18 is a can water pull amount adjustment valve.

Regarding the feed water circulation flow rate control method of the economizer 4 in the waste heat recovery boiler having such a schematic configuration, #! This will be explained along with the control system diagram of S diagram.

As mentioned above, the purpose of controlling the water supply circulation flow rate of the economizer 4 is to prevent the economizer 4 from steaming. For this control, a gas turbine load detector 19 that monitors the load state of the gas turbine, an atmospheric temperature detector 20 that detects the suction temperature of the gas turbine, and a drum pressure detector #1 are used.
6, a water supply humidity detector 15 that detects the water supply fM at the outlet of the economizer, and a circulation flow meter 1 that detects the circulating flow rate of the economizer 4.
4 S detection means are provided.

Based on the detection signal from the primary gas turbine load detector 19, an arithmetic relay 21 generates a preceding signal for the economizer feed water circulation flow rate corresponding to the load of the gas turbine. FIG. 3 is a characteristic diagram showing the relationship between the gas turbine load and the economizer feed water circulation flow rate used for this calculation. Since the amount of gas turbine exhaust gas changes depending on the atmospheric temperature, the value of the preceding signal is corrected by multiplying it by the temperature coefficient in the multiplier 22 in response to the detection signal from the atmospheric temperature detector 20, so that the signal does not change suddenly. The signal is input to the adder 24 through the change rate limiter 23 .

Based on the detection signal from the drum pressure detector 16, the calculator 2
5, the water supply circulation flow rate of the economizer 4 is calculated according to the drum pressure, and the result is input to the high value selector 26. The water used in this economizer 4 is for temperature detection.
Drum pressure and circulation flow rate adjustment valve opening (water supply circulation flow rate)
The relationship is shown in Figure 4.

Further, the detection signal of the drum pressure detector 16 is input to the calculator 27, and it is determined whether or not the steaming region has been reached based on the relationship between pressure and temperature shown in FIG. 5, and the calculation result is used as the set value. The comparator 28 is manually operated. The actual measured value from the feed water temperature detector 15 is input to the comparator 28 and compared with the set value. The comparison result is switching relay 29. The deviation amount outputted from the comparator 28 is proportionally integrated and inputted to the adder 24 via a proportional integrator 30 for stabilizing control, and the calculation result of the calculation relay 21 is added thereto. This added value becomes the circulation flow rate setting value, and the manual/automatic operation device 31
The measured signal from the circulating flowmeter 14 is inputted to the comparator 32 after passing through a square root calculator 33 and a multiplier 34 for temperature correction of the flow rate, and is then inputted to the comparator 32, where it is compared with the circulating flow rate setting value. be compared. Note that the actual measurement signal output from the multiplier 34 is
1 (see FIG. 1) is also sent to the control system (not shown).

The deviation amount output from the comparator 32 is proportionally integrated by a proportional integrator 35 in order to stabilize the control, and then the changeover relay 3
6 is output.

The signal generator 37 detects when the boiler banking is stopped and outputs a full close signal to fully close the economizer circulation flow control valve 13, and the full close signal is sent to the signal switching relay 38. The signal is input to the switching relay 36 via a change rate limiter 39 for limiting the rate of change. The signal output by switching at this switching relay 36 is transmitted to the automatic/manual operating device 4.
0 to the economizer circulation flow rate regulating valve 1-3, and the water supply circulation flow rate is controlled by adjusting the opening degree of the valve.

In such a control system, the drum pressure when the boiler banking is stopped is detected by the drum pressure detector 16, and based on the detection signal, the arithmetic unit 25 sets the water circulation flow rate of the economizer 4 corresponding to the drum pressure. be done. After the gas turbine is ignited, the switching relay 38 operates to send the setting signal for the water supply circulation flow rate to the economizer circulation flow rate regulating valve 13, and the regulating valve 13 is adjusted to a predetermined opening degree based on the setting signal. A set amount of water passes through the economizer 4.

This state continues until just before the gas turbine is installed, and at the same time the switching relay 36 operates, the output from the comparator 32 side is sent to the circulation flow rate adjustment valve 13, which prevents steaming from the original energy saving device. Switch to control. Then, as described above, the set value output from the adder 24 and the actual measurement value from the circulation flow meter 14 are compared and calculated by the comparator 32, and the opening degree of the circulation flow rate regulating valve 13 is adjusted so as to approach the set value. It will be done.

Note that if the economizer 4 reaches the steaming region between the gas turbine ignition and the gas turbine joining, the high value selector 2
This signal is preferentially selected in step 6, and the opening degree of the circulation flow rate regulating valve 13 is adjusted using that signal.

In the above embodiment, by setting the carbon-saving supply water circulation flow rate within the amount of water held in the deaerator, it is possible to prevent an increase in the amount of dissolved oxygen due to condensate makeup to the deaerator, and also to reduce the amount of water in the water supply. Pump power can be saved.

The present invention has the above-mentioned configuration, and the control of the water supply circulation flow rate in the economizer from gas sowing is performed proactively, and the hunting phenomenon due to repeated rapid and sudden decreases in the circulation flow rate does not occur, and the control System 0 is stable.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram of a waste heat recovery boiler according to an embodiment of the present invention, the jls diagram is a feed water circulation flow rate control system diagram of the economizer in the boiler, and Fig. 3 is a diagram showing the gas turbine load and the set feed water.・Characteristic diagram showing the relationship with water circulation flow rate. Figure 4 is a characteristic diagram showing the relationship between the drum pressure of the waste heat recovery boiler and the opening degree of the economizer feed water circulation flow rate regulating valve. Figure 6 is the drum pressure and temperature. FIG. 4... Energy saver, 11... Water supply flow rate adjustment valve, 13... Energy saver circulation flow rate adjustment valve, 14...
... Circulation flow meter, 15 ... Feed water temperature detector, 16 ... Drum pressure detector, 19 ...
- Gas turbine load detector, 20... Atmospheric temperature detector, 36.38... Switching relay. Figure 2 s3 Figure 4 ai2 Pressure Figure 5■ Force

Claims (1)

[Claims] 1. A water supply temperature detection means for detecting the temperature of the water supply at the outlet of the energy saver, a water supply circulation flow rate adjustment means for adjusting the water circulation flow rate of the energy saver based on a detection signal from the water supply temperature detection means, and a energy conservation device. After the preceding water supply circulation means circulates the water in a predetermined amount for a predetermined amount of time from the start of gas flow to the economizer, the supply water temperature detection means and the water supply circulation 1lI- 1. A water economizer water circulation flow rate control device, comprising a control switching means for switching to control of the water circulation flow rate using a position adjustment means.