JPS6159104A - Controller for water level in drum - 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 [Technical Field of the Invention] The present invention relates to a combined cycle plant that combines a gas turbine device 1''l and a steam turbine device driven by the thermal energy of its exhaust gas. This invention relates to a drum water level control i11 device that can suppress large fluctuations in the drum water level of the device.

[Technical Blueprint of the Invention] Composite cycle plants, which combine gas turbine equipment and steam turbine equipment, are increasingly being used in thermal power plants to meet the need for energy conservation.

Figure 4 shows a schematic configuration example of a combined cycle plant, which includes one or more gas turbine units 1, the same number of exhaust heat recovery boiler units 2, and is driven by the steam generated by the exhaust heat recovery boiler units. and at least one steam turbine device 3.

The gas turbine device 1 includes a compressor 11, a combustor 13 that mixes pressurized air discharged from the compressor with fuel supplied from a fuel pipe 12, and combusts the mixture, and a high-temperature, high-pressure combustion gas discharged from the combustor. The gas turbine 14 is driven by a gas turbine 14, and a power generation tank 15 is driven by the gas turbine.

Exhaust gas from the gas turbine 14 is guided to the exhaust heat recovery boiler device 2 through the exhaust gas ducts 1 to 16.

The exhaust heat recovery boiler device 2 includes an economizer 22 that preheats the water introduced from the water supply pipe 21, a drum 23 that receives the preheated water, an evaporator 24 that evaporates the drum water in the drum, and a steam generator in the drum 23. It is equipped with a superheater 25 for heating the water.

The superheated steam generated by the superheater 25 is passed through the steam pipe 26.
B and is led to the steam turbine device 3 through the boiler outlet valve 27.

The hot air turbine device 3 includes a steam turbine 31 and a steam pipe 2.
a steam header 32 and a steam control valve 33 inserted into the
A condenser 34 that condenses exhaust steam from a hot air turbine, a bypass steam pipe 35 that bypasses between the upstream side of the steam header 32 and the condenser 34, and a bypass valve inserted in this bypass steam pipe. 36J5 and a desuperheater 37. Reference numeral 38 indicates a power generation unit driven by the steam turbine 31.
1 and the water supply control valve 42, and flows back from the water supply pipe 21 into the exhaust heat recovery boiler device 2.

In the combined cycle plant configured as described above,
The drum 23 has a drum water level detection 28 for detecting the water level.
A steam flow meter 29 is inserted into the steam pipe 26 upstream of the boiler outlet valve 27 to measure the drum-generated steam m. Reference numeral 43 indicates a water supply flow meter that is inserted into the water supply pipe 21 and measures the flow rate of water supplied to the exhaust heat recovery boiler device 2 .

The water supply control device 5 calculates signals from the drum water level detection 28, the drum flow meter 29, and the water supply flow ω5143, and
The opening degree of the water supply control valve 42 is adjusted so that the drum water level is constant.
i control.

[Problems in the Background Art] As described above, in the conventional drum water level control i20 device, the drum water level is kept constant by the three elements a and (I'n) based on the drum water level, steam flow rate, and water supply flow rate. However, if the thermal compensation or temperature of the exhaust gas discharged from the gas turbine 14 suddenly increases, the saturated water will evaporate to a large amount Lh in the evaporator 24, and the generated steam bubbles will cause the drum The water level in 23 is 5'I: Always rising.

On the other hand, if the flow rate or temperature of the exhaust gas from the gas turbine 14 suddenly decreases, the amount of steam bubbles generated within the seafood container 24 decreases, and the drum water level decreases abnormally.

As described above, in the conventional drum water level control device, an increase or decrease in generated steam bubbles acts as a disturbance on the drum water level. In particular, if the drum water level rises abnormally, water droplets will mix into the generated steam, causing erosion in the superheater, steam turbine, and the like. Further, sudden fluctuations in the drum water level affect the drum water level control system, causing level hunting.

[Objective of the Invention 1] The present invention has been made to eliminate the above-mentioned drawbacks of the prior art iJ3.
By introducing the rate of change of temperature and temperature into the control element, we have developed a drum water level control device that can predict the volume change of the steam bubbles generated in the evaporator and suppress large fluctuations in the drum water level. This is the purpose.

[Summary of the invention] The drum water level control device of the present invention includes a gas turbine device,
Ill: J5 is installed in a combined cycle plant equipped with an exhaust heat recovery boiler device that generates steam using gas as a heat source, and a steam turbine device that is driven by the steam from this +JF heat recovery boiler equipment. A water supply control device that maintains a constant water level in the drum by controlling the opening degree of a water supply control valve inserted in the water supply piping of the recovery boiler equipment is connected to a signal from a water supply flowmeter inserted in the water supply piping, A signal from a drum water level detector installed in the drum, a signal from a steam flow meter inserted in the steam pipe of the exhaust heat recovery boiler device, a flow rate change signal of the exhaust gas of the gas turbine, and a signal of the rate of change of the exhaust gas of the gas turbine. It is characterized in that the opening degree of the water supply control valve is controlled by five-element control based on a temperature change rate signal.

[Embodiments of the Invention] Next, the present invention will be described in detail with reference to Fig. M1. NaJ'
3. J3 in FIG. 1, the same parts as in FIG. 4 are given the same reference numerals, and only the differences will be explained.

In FIG. 1, an exhaust gas duct 16 of a gas turbine 14
An exhaust gas flow m detector 60 for detecting the exhaust gas flow m from the gas turbine 14 is inserted. Further, the exhaust heat recovery boiler device 2 is equipped with an exhaust gas temperature detector 70 that detects 8 degrees (exhaust gas).

The output signals of these n1 gas flow detectors 60 and exhaust gas temperature detectors 70, along with signals from the drum water level detector 28, steam flow meter 29, and feed water flow meter 43, are transmitted to the feed water 11.
4 is input to i1+control device 6.

This water supply system 12II device 6 is configured as a five-point control unit, calculates each flow rate 31 and input number 13 from the detector, and controls the opening degree of the water supply control valve 42.

FIG. 2 shows a specific example of the configuration of the water supply control device 6 shown in FIG.
The output signal from 43 is boosted by a Kato device 50, and the result is input to an lI2 difference calculator 51. This difference calculator calculates the required water supply flow rate at that time based on the deviation between the drum water level detection 28 and its level setting value and the signal input from the adder 50. ttiO outputs a deviation signal to the proportional integrator 52.

In the conventional three-element control system, the water supply control valve 42 was controlled by the output of the proportional integrator 52, but the drum water level control device of the present invention has a configuration in which five elements are controlled by adding two additional elements. has been done.

That is, the exhaust gas flow detector 601. :J, the detected exhaust gas flow rate is input to the flow ω change rate calculation unit 61 to calculate the change rate, and the output is given a predetermined gain by the amplifier 62, and then input to the upper and lower limit limiter 63. It is input to the adder 53 through.

On the other hand, the exhaust gas temperature signal detected by the exhaust gas temperature detector B70 is input to a temperature change rate signal device 71 to determine the rate of change, and its output is input to an adder 53 through an amplifier 72 and an upper/lower limit limiter 73. Ru.

The adder 53 includes the aforementioned proportional integrator 52 and upper and lower limit limiter 63.
J5 J: Adds the signals from 73 and 1-. The output signal of this increase/stop device is supplied through the upper and lower limit limiter 54 (!-
:l i! ii valve/I2 and controls its opening degree n+
+-yru.

By using a water supply control IT table device with such a configuration, it is possible to detect in advance changes in the volume of steam bubbles generated in the evaporator due to changes in the flow rate and preparation of exhaust gas from the gas turbine. The opening degree of the water supply control valve 42 can be controlled in advance of the case using the three-element system described above.

Next, a modification of the present invention will be explained.

In the embodiment shown in FIG.
The output signal of 1 is input to the comparator 81 and compared with the υ1 gas flow m change rate setting vessel. This comparator 81 outputs a signal of level "1" when an input exceeding a set change rate of exhaust gas flow is received, and otherwise outputs a signal of level "Ort".

Similarly, the output signal of the exhaust gas (temperature change rate calculator 71) is input to the comparator 82 and compared with the 4 degree change rate setting field.

This comparator 82 outputs a signal of level "1" if there is an input exceeding a set rate of temperature change, and otherwise outputs a signal of level "O".

The output signals of comparators 81 and 82 are multiplied by U Fi 83, and the output thereof is input to relay circuit 84. The proportional integrator 52 and J
:The output of the function generator 85 is switched by a switch 86.

Therefore, when the rate of increase in the exhaust gas flow rate and the exhaust gas temperature both exceed their respective set values, a forced closing command is passed from the function generator 85 to the water supply control valve 42 through the switch 86.

Note that the switching contact output of the relay circuit 84 is connected to the proportional integrator 5.
It is also used for the auto balance of 2. This is done so that when the forced close command from the function generator 85 is released, the output of the proportional integrator 52 matches the opening degree of the water supply control valve 42 at that time, and the sudden change in the opening degree of the water supply control valve at the time of switching occurs. To prevent this, an autobalance signal 87 is output from the function generator 85 to the proportional integrator 52.
When the water supply control valve 42 follows the output of the function generator 85, the output of the proportional integrator 52 also follows, making bumpless switching possible.

According to the water supply control device having such a configuration, the exhaust gas flow f
f1-1') Even if the temperature rises rapidly, it is possible to prevent the drum water level from rising rapidly due to an increase in the body σ1 of vapor bubbles generated in the evaporator.

In the embodiment shown in FIG. 1, the IJI gas diversion of the gas turbine 14 is measured using the gas flow darkness detector 60, but if this is difficult or impossible,
The exhaust gas flow rate detector 60 is omitted and the fuel distribution 'fp is used instead.
At the same time, the fuel detection device is connected to the air pipe 17 of the compressor 11.
detection'! A device may be provided to augment the output signals of these detection devices into an exhaust gas flow rate signal of the gas turbine and input this signal to the water control III device 6.

[Effects of the Invention CA] As explained above, in the present invention, the feed water flow m is controlled prior to the three-line control O11 according to the rate of change of the temperature of the exhaust gas flow m)b of the gas turbine. Fluctuations in the drum water level due to exhaust gas compensation and changes in the volume of steam bubbles generated within the evaporator due to temperature changes can be prevented, and a highly reliable drum water level control device can be obtained.

[Brief explanation of drawings]

FIG. 1 is a system diagram showing an embodiment of a composite Nicle plant to which the present invention is applied, and FIGS. Figure 4 is a system diagram showing a conventional combined cycle plant. 1... Gas turbine device 2...
......Exhaust heat recovery boiler device 3...
...Steam turbine device 5.6 ... Water supply control device 11 ... Compressor 12 ...
・・・・・・・・・Fuii + Piping 13・・・・・・・・・
...Combustor 14 ...... Gas turbine 15.38
...Power generation 1G...Exhaust gas duct 17...
・・・・・・・・・Air piping 21・・・・・・・・・・
...Water supply pipe 22...Economizer 23...Drum 24...Focuser 25 .........Superheater 26...Steam pipe 27...Boiler outlet valve 28...
......Drum water level detector 29...
・・・・・・Steam flow meter 31・・・・・・・・・・・・
Steam turbine 32...Steam header 33...Steam control valve 34...
......Condenser 3 5......Bypass steam pipe 36...
......Bypass valve 37...
...Desuperheater 4 1...Water pump 42...
......Water supply control valve 43...
・Water supply flow i″t1 total 50.53... numbing device 51...... difference calculating unit 52...
......Proportional integrator 54.63.73...Upper/lower limit limiter 60...Exhaust gas flow rate detector 61.
・・・・・・・・・Flow m change rate calculator 62.72・
...Amplifier 70...Exhaust gas temperature detector 71.
・・・・・・・・・1 degree change rate calculator 81.82・
... Comparator 83 ...... Multiplier 84 ...... Relay circuit 85 ...
......Function generator 86...
...Switcher 87... Autobalance signal representative Patent attorney Sa Suyama - Figure 2 Figure 3

Claims (5)

[Claims] (1) In a combined cycle plant comprising a gas turbine device, an exhaust heat recovery boiler device that generates steam using the exhaust gas as a heat source, and a steam turbine device driven by the steam from the exhaust heat recovery boiler device, A water supply control device that maintains a constant water level in the drum by controlling the opening degree of a water supply regulating valve inserted in a water supply pipe of the exhaust heat recovery boiler device receives a signal from a water supply flow meter inserted in the water supply pipe, and A signal from a drum water level detector installed in the drum, a signal from a steam flow meter inserted in the steam pipe of the exhaust heat recovery boiler device, a flow rate change signal of the exhaust gas of the gas turbine, and a signal of the rate of change of the exhaust gas of the gas turbine. A drum water level control device characterized in that the opening degree of the water supply control valve is controlled by five-element control based on a temperature change rate signal. (2) The feed water control device includes an adder that adds the output signals of the feed water flow meter and the steam flow meter; inputs the output of this adder, the output of the drum water level detector, and the level setting value, and calculates the required feed water flow rate. a deviation calculator that calculates; a proportional integrator that proportionally integrates the signal from the deviation calculator; a flow rate change calculator that calculates the time rate of change in the exhaust gas flow rate based on the output of the exhaust gas flow rate detector; a temperature change rate calculator that calculates the time rate of change in exhaust gas temperature based on the output of the temperature detector; an addition that adds signals from the proportional integrator, the flow rate change calculator, and the temperature change rate calculator; 2. The drum water level control device according to claim 1, further comprising: a container; and; (3) The drum water level control device according to claim 2, wherein the output of the adder is guided to the water supply control valve through the upper and lower limit limiters. (4) The feed water control device includes an adder that adds the output signals of the feed water flow meter and the steam flow meter; inputs the output of this adder, the output of the drum water level detector, and the level setting value, and calculates the required feed water flow rate. A deviation calculator that calculates; a proportional integrator that proportionally integrates the signal from the deviation calculator; a flow rate change calculator that calculates the time rate of change in the amount of exhaust gas based on the output of the exhaust gas flow rate detector; a temperature change rate calculator that calculates the time rate of change in exhaust gas temperature based on the output of the temperature detector; a comparator that compares the output of the flow rate change rate calculator with a flow rate change rate set value; and the temperature change A comparator that compares the output of the rate calculator with the temperature change rate set value; A multiplier that multiplies the outputs of both of the comparators; The output of this multiplier operates a switch, and a function generator or proportional integral 2. The drum water level control device according to claim 1, further comprising: a relay circuit for inputting the output of the drum to the water supply control valve. (5) The drum water level control device according to claim 4, wherein the autobalance signal from the function generator is input to the proportional integrator.