KR19990008556U - Drum level control circuit device of heat recovery boiler for power plant - Google Patents

Abstract

The present disclosure relates to a drum level control circuit device for constantly adjusting the water level in the drum of the heat recovery boiler in a power generation facility. The drum level control circuit device of the conventional heat recovery boiler has a problem in that the drum level cannot be accurately adjusted when the drum level rises rapidly due to a problem such as uneven inflow of hot combustion gas from the gas turbine. Therefore, under the technical problem to solve this problem, the drum level control circuit device according to the present invention is a two-element control unit 20 in addition to considering the pressure in the drum in addition to the one-element control unit for controlling the drum level in the low load region. By providing a constant control of the drum level, it is possible not only to effectively control the level of the drum, but also to stably operate the entire power generation equipment, thereby improving the facility efficiency.

Description

Drum level control circuit device of heat recovery boiler for power plant

The present invention relates to a drum level control circuit device for constantly adjusting the level in the drum of the heat recovery boiler of the power generation equipment, in particular, a drum level control circuit to effectively control the level of the drum by additionally using the pressure element in the drum Relates to a device.

In general, the power generation facilities can maintain the normal operation of the boiler by maintaining a constant level in the heat recovery boiler.

First, a description will be given by taking an example of a general thermal power plant among the power generation facilities in which a conventional heat recovery boiler is installed. 1 is a schematic view showing a general thermal power plant. As shown in the figure, the thermal power plant has a gas turbine 100, a heat recovery boiler 110 and a steam turbine 120. The turbine 100 is rotated by the high temperature and high pressure combustion gas generated by the combustion of the fuel, the combustion gas rotated turbine is discharged to the outside of the gas turbine. The heat recovery boiler 110 serves to absorb the heat of the combustion gas to make water into steam and to supply the generated steam to the steam turbine 120, in which an economizer 110a and an evaporator 110b are disposed. , A superheater 110c, a drum 110d, and a feed water control valve 110e. When water is supplied into the breaker 110a by opening the water supply control valve 110e, the water is first warmed by the heat recovered from the gas turbine 100 and flows into the drum 110d. The water in the drum (110d) is changed to steam while passing through the evaporator (110b), the steam is passed to the superheated steam while passing through the superheater (110c) is supplied to the steam turbine 120. In this way, the water is changed to the superheated steam state through the heat recovery boiler 110 is supplied to the steam turbine 120, the superheated steam by rotating the turbine of the steam turbine 120 to transmit a rotational force to the generator 130 connected thereto To produce electricity. In addition, by connecting the condenser 140 and the feed water pump 150 between the steam turbine 120 and the feed water control valve 110e of the heat recovery boiler, and after driving the turbine, by cooling the steam discharged from the steam turbine with cooling water The water is recovered again and the recovered water can be supplied to the water supply control valve 110e. This will allow us to continue to produce electricity.

On the other hand, in order to continue to operate the power generation equipment normally, the level of the drum 110d of the heat recovery boiler should always be kept constant. For this purpose, a drum level control circuit device in which a one-element controller and a three-element controller are mixed is used. As such, the reason why the control is divided into the one element control unit and the three element control unit is to prevent the flow rate from being kept constant due to the limitation of the measurement range of the measuring instrument when the flow rate is small. Of these, the one-element control unit is used when the amount of steam generation in the drum 110d in the low load region is below a predetermined level, so that the drum level control is controlled in association with the flow rate flowing into the drum. The three-element control unit is used when the amount of steam generated in the drum 110d is higher than a predetermined level in the high load region, and the adjustment of the drum level is discharged from the drum 110d to the steam turbine 120. It is controlled by three input elements, the steam flow rate and the drum level. Accordingly, the heat recovery boiler 110 is controlled by the drum water level control circuit device having the one-element control unit and the three-element control unit, so that the drum level is constantly adjusted so that the entire power generation equipment is in a normal state. It can be operated constantly.

However, the drum level control circuit device of the conventional heat recovery boiler has a problem in that the drum level cannot be accurately adjusted when the drum level rises rapidly due to a problem such as uneven inflow of hot combustion gas from the gas turbine. Had. Accordingly, the present invention has been made to solve the above problems, the object of the present invention is to provide a drum level control circuit device of the heat recovery boiler to stably operate the heat recovery boiler by effectively adjusting the drum level.

1 is a schematic view showing a general thermal power plant;

2 is a block diagram of a drum level control circuit device according to the present invention.

※ Explanation of symbols for main parts of drawing

10: 3-element control unit 11: Drum level meter

12: steam flow meter 13: water flow meter

14, 17: comparator 15: first proportional integral controller

16, 26: adder 18: second proportional integral controller

20: two-element control unit 21: drum pressure measuring instrument

22: multiplier 23: differential

24: controller 25: third proportional integral controller

30: Signal selector 31: Signal monitor

32: automatic manual changer 34: control valve

100: gas turbine 110: array recovery boiler

110a: Binder 110b: Evaporator

110c: superheater 110d: drum

110e: water supply control valve 120: steam turbine

130: generator 140: avenger

150: water supply pump

Features of the present invention for achieving the above object is to control the opening and closing of the water supply valve to maintain a constant water level in the drum of the heat recovery boiler in the power generation equipment, the water level in the drum in the high load area, the steam released from the boiler outside the boiler It is provided with a three-element controller for controlling the drum level by setting each of the flow rate and the feed water flow into the drum as an input element, and a one-element control unit for controlling the drum level in conjunction with the flow rate flowing into the drum in the low load area, A drum level control circuit device for selectively using a three-element control section and a one-element control section, wherein the drum level control circuit device has a two-element control section further configured to further set pressure in the drum as an input element.

Hereinafter, with reference to the accompanying drawings to explain the configuration and operation of the present invention.

2 is a block diagram of a drum level control circuit device according to the present invention. Unlike the conventional control circuit device, the drum level control circuit device adjusts the level of the drum in consideration of the pressure element of the drum. As shown in the figure, the control circuit device is composed of a three element control unit 10 and a two element control unit 20 in consideration of the pressure element in the drum.

The three-element control unit 10 controls the drum level in consideration of three input elements: the water flow rate flowing into the drum (110d in FIG. 1), the steam flow rate discharged from the drum to the steam turbine (120 in FIG. 1), and the drum level. Into the drum from the drum level meter 11 for measuring the drum level, the steam flow meter 12 and the condenser (140 in Fig. 1) for measuring the flow rate of the steam discharged out of the heat recovery boiler from the drum A water supply flow rate measuring device 13 for measuring the water supply flow rate of water to be used is provided. In addition, the drum level meter 11, the steam flow meter 12 and the water supply flow rate meter 13 are comparators (comparable to compare, control, and add the measured values for the measured drum level, steam flow rate and feed water flow rate, respectively). 14), the first proportional integral controller 15, the adder 16, the comparator 17 and the second proportional integral controllers 18, respectively. In particular, the comparator 14 is set with a drum level set value optimally set for the level in the drum, so that it can be compared with the actual level value in the drum measured from the drum level gauge 11. In addition, the two-element controller 20 in this figure is provided with a drum pressure measuring device 21 for measuring the pressure in the drum and a drum level measuring device 11 for measuring the drum level. The drum level gauge 11 is used in the three-element controller 10 and the two-element controller 20, but may be installed as a separate device to be used only in the two-element controller 20. In any case, the two-element control unit 20 includes a drum pressure measuring unit 21 and a drum level measuring unit 11. The drum pressure measuring unit 21 and the drum level measuring unit 11 include drum pressures measured from the respective devices. And a multiplier 22, a differentiator 23, a comparator 24, a third proportional integral controller 25, and an adder 26 for multiplying, differentiating, comparing, controlling, and adding the drum level measurement values, respectively. . In addition, the signal selector 30 is coupled to the three element controller 10 and the two element controller 20 in a state connected to the signal monitor 31 extended from the steam flow meter 12. Here, the signal monitor 31 is connected with the steam flow meter 12, and compares the steam flow rate value actually measured from the steam flow rate meter with the upper and lower limits of the preset steam flow rate to make the resultant state as a control signal and selects a signal selector ( 30) to send. The signal selector 30 enables the optimum selection of the output data values of the two-element controller or the three-element controller according to the resultant state, and the control valve 34 is connected to the signal selector 30 to open and close appropriately according to these data value results. Will be. In addition, the control valve 34 has an automatic manual changer 32 disposed between the signal selector 30 and the control valve 34 so that the opening and closing operation can be switched automatically or manually.

Therefore, when the drum level measuring unit 11 of the three element control unit 10 measures the actual drum level and sends the measurement data to the comparator 14, the comparator 14 compares the preset drum level setting value and removes the deviation. 1 is input to the proportional integral controller 15. The output value output from the first proportional integral controller 15 is added to the steam flow rate value measured from the steam flow meter 12 in the adder 16. The added value is compared with the water supply flow rate value measured by the water supply flow rate meter 13 in the comparator 17 so that the deviation is input to the second proportional integral controller 18. On the other hand, the drum pressure measuring unit 21 of the two-element control unit 20 measures the actual pressure in the drum and sends the measured data to the differentiator 23 through the multiplier 22. The measurement data is multiplied regularly through the multiplier 22 and the differentiator 23, and the rate of change is calculated. The drum level data measured by the drum level gauge 11 is compared with the drum level set value preset by the comparator 24 to input the deviation to the third proportional integral controller 25. The output value output from the third proportional integral controller 25 is added to the calculated value from the differentiator 23 in the adder 26 and the resultant value is sent to the signal selector 30. The signal selector 30 selects an appropriate control condition by comparing the result values of these three-element and two-element controllers with the control signals from the signal monitor 31. Accordingly, after the automatic / manual operation is determined by the automatic manual changer 32, the control valve 34 can be opened and closed appropriately so that the drum level can be constantly adjusted.

As described above, the drum level control circuit device according to the present invention, in addition to the one-element control unit responsible for the control of the drum level in the low load area, by further considering the pressure in the drum to be able to adjust the drum level constant, the drum It can not only effectively control the water level, but also stably operate the entire power generation equipment, and thus the efficiency of the facility is improved.

Claims (3)

The opening and closing of the water supply valve is controlled to maintain the water level in the drum of the heat recovery boiler in the power generation facility. 3-element control unit for controlling the drum level by setting the water level in the drum in the high load region, the flow rate of steam discharged from the drum to the outside of the boiler, and the feed water flow rate flowing into the drum as input elements, and the drum in the low load region. A drum level control circuit device having a one element control unit for controlling the drum level in association with a flow rate introduced into the drum, wherein the three element control unit and the one element control unit are selectively used. And a two-element controller configured to further set pressure in the drum as an input element in addition to the one-element controller. The method of claim 1, And a drum level meter, a drum level meter, a multiplier, a differential, a comparator, a controller, and an adder. The method of claim 2, A drum level control circuit device in which the drum level meter is combined with a drum level meter of the three element control unit.