JPH0133767Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention is directed to a plurality of gas turbine power generation devices each consisting of a gas turbine and a generator driven by the gas turbine, and multiple heat recovery boilers that generate steam using heat recovery boilers, a steam header that aggregates the steam generated by these heat recovery boilers, and steam driven by the steam supplied from the steam headers. The present invention relates to a control device for a steam turbine in a combined cycle power generation facility including a steam turbine power generation device including a turbine and a generator driven by the steam turbine.

[Technical background of the invention]

In a combined cycle power generation facility having a plurality of gas turbine power generation devices, each gas turbine power generation device can be operated individually. Therefore, the amount of steam generated by each heat recovery boiler attached to each gas turbine is determined by the load of each gas turbine, and the steam turbine is operated with steam commensurate with the sum of the amounts of steam generated by each individual gas turbine. It turns out.

On the other hand, in this type of combined cycle power generation equipment, if a problem occurs on the heat recovery boiler side and steam generation becomes impossible, cold water from the heat recovery boiler flows into the steam turbine via the steam header, and the steam There is a risk of damage to the turbine. In order to prevent cold water from flowing into the steam turbine, in general thermal power turbine equipment, the steam pressure at the inlet of the steam turbine is detected, and if the detected pressure drops below a predetermined value, a steam regulator installed at the turbine inlet side is activated. The inlet steam pressure drop prevention device restricts the valve to its no-load opening to prevent cold water from flowing into the steam turbine.

[Problems with background technology]

In the above-mentioned inlet steam pressure drop prevention device, one boiler is provided for one steam turbine.
Normal thermal power generation equipment with one unit per unit can fully perform its functions, but the above-mentioned combined cycle power generation equipment, which operates multiple heat recovery boilers in parallel, cannot fully perform its functions. .

[Purpose of invention]

The present invention was developed in consideration of the above circumstances, and its purpose is to provide a steam turbine equipped with an inlet steam pressure drop prevention function that prevents cold water from flowing into the steam turbine due to problems with the heat recovery boiler in combined cycle power generation equipment. The purpose of this invention is to provide a control device for

[Summary of the idea]

In order to achieve the above object, the present invention includes a calculation means for calculating the total output by summing the output of each gas turbine power generator, and a calculation means for calculating the generated steam pressure of the heat recovery boiler for the total output calculated by the calculation means. A heat recovery boiler characteristic circuit to simulate and an inlet steam pressure drop prevention calculation circuit to control the steam pressure at the inlet of the steam turbine using the generated steam pressure simulated by the heat recovery boiler characteristic circuit as a pressure set value are provided. It is characterized by this.

Multiple gas turbines, heat recovery boilers, 1
When operating a steam turbine in a combined cycle power plant in combination with a steam turbine, in order to increase plant efficiency, constant pressure operation is performed at low loads, and at other times the steam control valve is fully opened. It is common to operate at variable pressure.

FIG. 1 shows an example of such an operation system, with the horizontal axis showing the power generation output and the vertical axis showing the steam turbine inlet steam pressure B. In this diagram,
Until the low load point a, the steam turbine inlet steam pressure B is controlled to a constant value x by the inlet steam pressure control circuit built into the steam turbine control device, and the steam control valve reaches full open at point a. There is no pressure control function after point a when the heat recovery boiler reaches full opening, and as the amount of steam generated by the heat recovery boiler increases, the steam pressure at the inlet of the steam turbine increases, and the output of the steam turbine increases accordingly. do. Point b is the 100% load point, and at this output point the steam turbine inlet steam pressure also reaches the rated pressure y.

It is clear that the inlet steam pressure drop prevention device described in the above technical background is inappropriate for a steam turbine that performs variable pressure operation as described above. Further, it is known that variable pressure operation is performed even in thermal power generation equipment of one unit and one can, and an inlet steam pressure drop prevention device suitable for this is known.

The steam turbine inlet steam pressure drop prevention device according to the present invention is characterized in that its pressure setting value is determined in consideration of the characteristics of the heat recovery boiler based on the actual load of the gas turbine.

[Example of idea]

FIG. 2 shows an embodiment of the present invention.
Here, as an example, a combined cycle power generation facility consisting of a combination of three gas turbines, three heat recovery boilers, and one steam turbine is shown. Compressors 1a, 1b, 1c and generators 3a, 3b, 3c are connected to the three gas turbines 2a, 2b, 2c, respectively, thereby forming three sets of gas turbine power generation devices. Compressed air is supplied to the gas turbines 2a, 2b, 2c from their respective compressors 1a, 1b, 1c, and fuel mixed therewith is supplied to the gas turbines 2a, 2b, 2c through fuel stop valves 4a, 4b, 4c and fuel control valves 5a, 5b,
5c. Each gas turbine 2a,
Output control of the fuel pumps 2b and 2c is performed by controlling the flow rate of the incoming fuel to match the required load using the fuel control valves 5a, 5b, and 5c. The exhaust gas from each gas turbine 2a, 2b, 2c is guided to its own heat recovery boiler 6a, 6b, 6c, where steam is generated using the thermal energy contained in the exhaust gas. Heat recovery boilers 6a, 6b,
The steam generated in 6c is passed through check valves 7a and 7, respectively.
b, 7c and stop valves 8a, 8b, 8c, and are collected in a steam header 9. The collected steam is guided from the steam header 9 through the main steam stop valve 10 and the steam control valve 11 to the steam turbine 12 to drive it. A generator 3d is connected to the steam turbine 12, and both constitute a steam turbine power generation device. Exhaust steam from the steam turbine 12 is condensed in a condenser 13.

The output control of the gas turbines 2a, 2b, 2c is performed by controlling the fuel control valves 5a, 5b, 5c, but since this is not directly related to the gist of the present invention, illustration of the control device is omitted here. . Output control of the steam turbine 12 is performed by controlling the steam control valve 11. The control device will be explained below.

The rotational speed of the steam turbine 11 is detected as a frequency signal proportional to the rotational speed by a gear 14 directly connected to the turbine rotor and an electromagnetic pickup 15 disposed opposite the gear. This detection signal is converted into a voltage signal by a frequency/voltage converter 16. The actual rotational speed signal of the steam turbine 12 output from the frequency/voltage converter 16 is sent to the adder 17.
It is compared with the setting signal from the speed setter 18 and calculated. The speed deviation signal output from the adder 17 is input to the speed control calculation circuit 19, where a speed control signal is generated in accordance with the speed adjustment rate so as to make the speed deviation zero. This speed control signal is input to a first input of a low value priority circuit 20 having three inputs. A limit signal from a load limiter 21 is input to a second input terminal of the low value priority circuit 20 . Third
At the input end of the regulator valve no-load opening limiter 35, which will be described later.
A limit signal is input from. Low value priority circuit 20
compares the three inputs and outputs the signal with the lowest value as the steam control valve opening request signal. This opening request signal is compared with the control valve actual opening signal in an adder 22, and the deviation signal is subjected to gain adjustment in accordance with the characteristics of the control system in a preamplifier 23, and then power amplified in a power amplifier 24. It is input to the electro-hydraulic converter 25. The electro-hydraulic converter 25 converts the control valve opening degree deviation signal output from the power converter 24 into a mechanical displacement signal, and converts the control valve opening degree deviation signal outputted from the power converter 24 into a mechanical displacement signal,
The opening degree of 1 is adjusted so as to be interposed in the steam control valve opening degree request signal. The mechanical displacement signal of the electro-hydraulic converter 25 is negatively fed back to the adder 22 via the differential transformer 27 and the demodulator 28.

On the other hand, the outputs of the generators 3a, 3b, 3c driven by the gas turbines 3a to 3c are detected by generator output detectors 29a, 29b, 29c, and the sum of the detected outputs is added to the adder 30. It is determined by The total output signal of the generators 3a, 3b, 3c determined by the adder 30 is input to a heat recovery boiler characteristic circuit 31, where the characteristics of the heat recovery boilers 6a to 6c are simulated. That is, the heat recovery boiler characteristic circuit 31 calculates the delay in the change in steam pressure of the heat recovery boiler that occurs when there is a change in the output of the gas turbine, and calculates the generated steam pressure of the heat recovery boiler corresponding to the output of the gas turbine. , is simulated by calculation taking into account the delay in gas turbine output change, and is output as the set pressure of the inlet steam pressure drop prevention calculation circuit 34. The reason for doing this is that, for example, a failure of the heat recovery boiler causes a drop in the steam pressure at the inlet of the steam turbine, so it is necessary to determine the pressure setting value based on the output of the gas turbine. The pressure detector 3 detects the main steam pressure on the inlet side of the main steam stop valve 10.
2, the heat recovery boiler characteristic circuit 31
The adder 33 performs a comparison operation with the pressure signal from the adder 33.
The deviation is input to the inlet steam pressure drop prevention calculation circuit 34 as a pressure deviation signal. The inlet steam pressure drop prevention calculation circuit 34 generates a steam control valve opening signal in accordance with the pressure regulation rate in accordance with the input pressure deviation. This steam control valve opening signal is inputted to the third input terminal of the low value priority circuit 20 via the control valve no-load opening limiter 35.

The inlet steam pressure of the steam turbine 12 changes depending on the output state of the gas turbines 2a to 2c, and the no-load opening degree of the steam turbine 12 also changes depending on the output of the gas turbine. The no-load opening limiter 35 provides this characteristic, an example of which is shown in FIG. In FIG. 3, the horizontal axis shows the main steam pressure X, the vertical axis shows the steam control valve opening Y, and the characteristic line C is the steam control valve no-load opening limit signal. It can be seen that this limit signal becomes smaller as the main steam pressure X becomes higher.

[Effect of idea]

As mentioned above, the inlet steam pressure drop prevention device in the present invention determines the pressure setting value by simulating the characteristics of the heat recovery boiler from the output of the gas turbine. For example, even if the main steam pressure decreases due to a failure of the heat recovery boiler, the system can quickly respond to it and prevent a situation where cold water flows into the steam turbine and causes damage to the steam turbine. can be prevented. moreover,
By adjusting the no-load opening degree of the steam control valve according to the state of the main steam pressure, it is possible to prevent the opening degree from being reduced below the no-load opening degree.

[Brief explanation of the drawing]

Fig. 1 is a characteristic diagram showing the characteristics of the steam turbine inlet steam pressure during variable pressure operation in a combined cycle power generation facility, Fig. 2 is a block diagram showing an embodiment of the present invention, and Fig. 3 is the device shown in Fig. 2. FIG. 3 is a characteristic diagram showing the no-load opening characteristic of the inlet steam pressure drop prevention calculation circuit in FIG. 2a, 2b, 2c...gas turbine, 3a, 3
b, 3c, 3d... Generator, 6a, 6b, 6c...
...Heat recovery boiler, 9...Steam header, 11...
Steam control valve, 12... Steam turbine, 15... Speed detection electromagnetic pickup, 16... Frequency/voltage converter, 17, 22, 30, 33... Adder, 1
8...Speed setter, 19...Speed control calculation circuit,
20...Low value priority circuit, 21...Load limiter, 2
5...Electro-hydraulic converter, 26...Adjustment valve oil cylinder, 27...
... Differential transformer, 28 ... Demodulator, 29 ... Generator output detector, 31 ... Heat recovery boiler characteristic circuit,
32...Pressure detector, 34...Inlet steam pressure drop prevention calculation circuit, 35...Adjustment valve no-load opening limiter.

Claims (1)

[Claims for Utility Model Registration] 1. Multiple sets of gas turbine power generation devices each consisting of a gas turbine and a generator driven by the gas turbine, and generating steam by using the exhaust heat of each of the gas turbines. A steam header that collects the steam generated by these heat recovery boilers, a steam turbine that is driven by the steam supplied from the steam header, and a steam turbine that is driven by the steam supplied from the steam header. In a steam turbine control device for a combined cycle power generation facility comprising a steam turbine power generation device consisting of a generator driven by a gas turbine generator, the control device for a steam turbine in a combined cycle power generation facility includes a calculation means for calculating the total output by summing the output of each gas turbine power generation device; A heat recovery boiler characteristic circuit that simulates the generated steam pressure of the heat recovery boiler for the total output determined by the calculation means, and the generated steam pressure simulated by this heat recovery boiler characteristic circuit as the pressure setting value. 1. A control device for a steam turbine in a combined cycle power generation facility, comprising: an inlet steam pressure drop prevention calculation circuit for controlling steam pressure at an inlet of the steam turbine. 2 Utility Model Registration Scope of Claims 1. In the control device according to claim 1, a no-load opening is provided on the output side of the inlet steam pressure drop prevention calculation circuit to provide a no-load opening limit value proportional to the supply steam pressure of the steam header. A control device for a steam turbine in a combined cycle power generation facility, characterized by being equipped with a temperature limiter.