JP2000161009A - Method and device for controlling steam turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To operate a steam turbine at the maximum operating point by always supplying the available maximum steam flow to the steam turbine. SOLUTION: Means 51-53 are arranged which measure steam flow extracted from each stage of a steam turbine middle stage, a set value of a steam turbine inlet steam flow is corrected based on the total value of a correction value by the linear function of the total value of the steam flow and the set value of the steam turbine inlet steam flow, and steam turbine inlet steam flow control means is controlled according to deviation between the corrected set value and the actually measured value of the steam turbine inlet steam flow.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for controlling a steam turbine, and more particularly, to a method for extracting steam from a middle stage of a steam turbine, which is suitable for use in a steam turbine power generation facility in a power plant. The present invention relates to a method and an apparatus for controlling a turbine.

[0002]

2. Description of the Related Art FIG. 1 shows a five-can boiler 11 to 1 using coke oven gas (C gas) and blast furnace gas (B gas) as fuel.
5 shows a system diagram of a steam turbine power plant constituted by No. 5. In each of the boilers 11 to 15 of this power plant, a gas in which C gas and B gas are mixed is burned, and water is converted into steam using the heat to generate high-pressure steam for rotating the steam turbine 22. are doing.

[0003] In the drawing, reference numeral 16 denotes a forced air ventilator (FDF) for feeding combustion air into the boiler, and 18 denotes
An induction ventilator (IDF) 20 for guiding the exhaust gas after being burned in each of the boilers 11 to 15 to a chimney (not shown) includes:
The steam receiver 24 for receiving the high-pressure steam generated in each of the boilers 11 to 15 is a generator that is directly connected to and driven by the turbine 22 that is rotated by the high-pressure steam supplied from the steam receiver 20. Turbine 22
Condenser for returning steam that has lost energy in water to water, 30
Is a deaerator for removing gas from the water generated by the condenser 28 and supplying it to the boilers 11 to 15;
Reference numeral 2 denotes a steam control valve for controlling the flow rate of steam (turbine inlet steam flow rate) supplied from the steam receiver 20 to the turbine 22, and reference numeral 34 denotes a governor for controlling the opening of the control valve 32. (Governors) and 36 are power generation controllers for controlling the governor 34 to adjust the turbine inlet steam flow rate.

There are various methods of controlling the steam turbine power generation equipment. When it is desired to secure an arbitrary power generation, a governor for controlling the turbine inlet steam flow by the power generation controller 36 is used. The power generation amount control for maintaining the power generation amount at an arbitrary constant value is performed by controlling the set value of No. 34.
If it is not necessary to maintain a constant power generation amount, and if it is desired to always generate power at the maximum power generation capacity that is full of the equipment capacity, the valve opening of the governor 34 is fixed at full open and the turbine inlet steam flow rate is reduced. Maximize power generation by maximizing. For these, various control methods have been devised depending on the operation method of the equipment.

[0005] For example, Japanese Patent Application Laid-Open No. 53-90544 discloses that a power fluctuation of a power generation plant using a bleed-type turbine in which steam is extracted from a middle stage of a steam turbine is detected, and the detected value is set to a predetermined output setting. A deviation value is determined by comparing the deviation value with the value, and the deviation value is input to the governor 34 as a flow control signal for the steam flowing into the turbine. It is described that the power generation output is kept constant by adjusting the amount.

[0006] Japanese Patent Application Laid-Open No. 3-31882 discloses that the maximum bleed pressure is always controlled regardless of the bleed flow rate used in the factory by controlling the last-stage bleed control valve opening to the maximum constant opening during maximum power generation. It is described that the maximum generator output that can be obtained in accordance with the bleed air flow rate at that time is obtained while keeping it constant.

In Japanese Patent Publication No. 61-20686, there are provided a bleed control valve control signal and a steam control valve control signal system, and these signals are used to determine the fluctuation of the bleed flow to avoid the fluctuation of the turbine output. In the case of the main steam flow rate maximum operation, the steam control valve control signal system constant is set to zero, and the decrease of this constant is added to the bleed air control valve control signal. The bleed control valve control signal system constant is set to zero, and the decrease of this constant is added to the steam control valve control signal. At the time of the water flow minimum operation, all the fluctuations of the bleed air flow are the fluctuations of the main steam flow, so that even in the fluctuation of the bleed air flow, only the main steam flow or the condensate flow is changed. It is described that allows the constant flow rate operation.

In Japanese Patent Publication No. 61-53528, power transmission / reception is controlled by controlling the flow rate of steam generated by the boiler or the opening of the bleed control valve so as not to exceed the upper and lower limits.
It describes that stable power transmission and reception power control and stable supply of steam into a factory can be performed.

[0009]

Normally, when it is not necessary to maintain the power generation amount at an arbitrary value and it is desired to generate the maximum power as an operation, the governor valve opening is fixed at full open and the turbine inlet steam is fixed. Although the flow rate is kept at a maximum, the turbine inlet steam flow rate is set by the processing capacity of the condenser 28, and basically the steam flow rate that can be processed by the condenser 28 is passed through the turbine 22. be able to.

However, in general, in the condensing steam turbine, in order to improve the turbine efficiency, some bleeding is performed from the middle stage of the turbine, and the steam is used as steam for the deaerator 30 and steam for the feed water heater. , Improving the efficiency of the entire plant. For this reason, the amount of steam that works until the end and finally returns as water to the condenser 28 is not always constant, but constantly changes depending on the turbine bleed flow rate. Since the turbine bleed flow rate varies depending on the load conditions of the entire plant, it is difficult to calculate its quantitative value by calculation, and is usually determined by the load of the entire plant. Therefore, when the steam turbine is operated, the steam turbine is operated at a value obtained by correcting the empirically known fluctuation amount of the turbine extraction flow rate from the maximum value of the turbine inlet steam flow rate. For this reason, there is a problem that the plant in which the load fluctuation is severe cannot always be operated at the operating point of the maximum efficiency of the steam turbine.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and always supplies a steam turbine with a maximum steam amount which can be processed by a condenser so that the steam turbine can be operated at a maximum operating point. The task is to

[0012]

SUMMARY OF THE INVENTION The present invention relates to a method for controlling a steam turbine in which steam is extracted from a middle stage of a steam turbine. The above problem is solved by correcting the set value of the steam flow control so as to always supply the maximum steam amount that can be supplied to the steam turbine.

Further, the flow rate of the extracted air from each of the middle stages of the steam turbine is measured, the total value is corrected by a linear function to obtain a correction value, and the correction value is added to the set value of the turbine inlet steam flow control. It is something to do.

Further, the correction coefficient of the linear function is changed by manually changing the turbine inlet steam flow to keep the turbine rotation speed constant, and performing a linear regression from the data of the turbine inlet steam flow and the turbine extraction flow at that time. Is to ask for it.

According to the present invention, there is further provided a steam turbine control apparatus for extracting steam from a middle stage of a steam turbine, wherein a turbine inlet steam flow rate measuring means for measuring a turbine inlet steam flow rate, and the turbine inlet steam flow rate measuring means. A turbine inlet steam flow rate controlling means for controlling the turbine inlet steam flow rate in accordance with the deviation between the turbine inlet steam flow rate measured in step 1 and the set value, and a bleed air flow rate for measuring the bleed air flow rate from each of the middle stages of the steam turbine. Measuring means, adding means for adding the bleed air flow rate measured by the bleed air flow rate measuring means to obtain a total value, and correcting the total value by a linear function to obtain a correction value, wherein the turbine inlet steam flow rate adjusting means A bleed air flow rate correction calculation means for correcting a set value, wherein the maximum steam amount that can be supplied to the steam turbine is always supplied to solve the above problem. A.

In the present invention, in order to solve the above problem, the turbine inlet steam flow rate adjusting means (for example, a turbine inlet steam flow rate regulator) is used so that the value of the turbine inlet steam flow rate can be controlled to be constant. In addition, the value of the turbine extraction flow rate of each stage is measured, and a correction value obtained by correcting the sum of the values by a linear function is added to the set value of the turbine inlet steam flow controller to correct the value. The maximum steam amount that can be processed by the condenser is always supplied to enable operation at the maximum operating point.

In the correction of the linear function based on the flow rate of the turbine bleed air, there are various error factors such as an error in the flow rate measuring method and an error due to the pressure fluctuation, and therefore cannot be corrected by simple addition and subtraction. Therefore, the turbine inlet steam flow rate is manually changed, and the load driven by the turbine, for example, the output of the generator is kept constant.From the data of the turbine inlet steam flow rate and the turbine bleed flow rate at that time, a linear regression is performed to obtain a linear function Can be obtained.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 2 is a system diagram showing a control system in a steam turbine control device according to an embodiment of the present invention.

The steam for power generation produced by a boiler (not shown) passes through a steam control valve 32 and passes through a steam turbine 22.
Supplied to The steam turbine 22 drives a generator 24 to generate power. The turbine inlet steam that has passed through the steam turbine 22 performs the work of driving the steam turbine 22, returns to the condenser 28, becomes condensed water, and is circulated and used again in the power plant. At this time, part of the turbine inlet steam flow rate becomes the turbine bleed flow rate, is extracted from the middle stage of the turbine, and is effectively used as steam for the deaerator and steam for the feed water heater, thereby improving the steam turbine efficiency. ing.

However, the flow rate of the turbine bleed air constantly varies depending on the load of the plant, and is not constant. For this reason, the amount of steam returned to the condenser 28 fluctuates according to the change in the turbine bleed flow rate, and satisfies the maximum processing capacity of the condenser 28, and the processing capacity of the condenser 28 has a margin. There is.

Accordingly, in the present invention, a turbine inlet steam flow transmitter 40 for measuring the turbine inlet steam flow is provided.
And a turbine inlet steam flow controller 42 for controlling the turbine inlet steam flow according to the deviation between the turbine inlet steam flow measured by the turbine inlet steam flow transmitter 40 and the set value. One-stage bleed flow transmitter 5 for measuring the bleed flow from each stage
1. Two-stage bleed flow transmitter 52 and three-stage bleed flow transmitter 5
3, an adder 56 that adds the bleed flow rates measured by the bleed flow transmitters 51 to 53 to obtain a turbine bleed flow total value X, and corrects the total value X with a linear function (correction coefficients a and b). And a bleed flow correction arithmetic unit 58 for determining the turbine inlet steam flow correction value Y and correcting the set value of the turbine inlet steam flow controller 42.

The turbine inlet steam flow transmitter 40 is
The turbine inlet steam flow rate is measured and input to the actual measured value (PV value) of the turbine inlet steam flow controller 42, and the set value (SV
After the PID calculation is performed on the deviation from the control value, the set value of the governor 34 is increased or decreased by the output value, and the steam control valve 32 is operated by the output of the governor 34 to control the turbine inlet steam flow at a constant value. I do.

The bleed flow transmitters 51 to 53 installed at each turbine bleed stage measure the value of the turbine bleed flow, add the values by an adder 56, and add the result to the total turbine bleed flow. The value X is input to the bleed flow correction calculator 58.

The bleed flow correction calculator 58 corrects the total value X by a linear function having correction coefficients a and b, and outputs a turbine inlet steam flow correction value Y. This correction value Y is added to the SV value of the turbine inlet steam flow controller 42 to correct the set value. As a result, the variation of the turbine extraction flow rate is corrected, and the steam flow rate supplied to the steam turbine 22 is always set to the full capacity of the condenser 28.

At this time, since the correction coefficients a and b of the bleed flow correction arithmetic unit 58 have various error factors such as errors in the flow rate detection method and errors due to pressure fluctuations, they cannot be corrected by simple addition and subtraction. A test was conducted to manually change the turbine inlet steam flow rate and keep the output of the generator 24 constant by keeping the rotation speed of the turbine 22 constant. At that time, the data of the turbine inlet steam flow rate and the turbine extraction steam flow rate were used. First, perform a first-order regression and find it.

With the above operation, the steam turbine 22
Is a value that takes into account the turbine bleed air flow rate, it is possible to pass the full steam flow rate of the condenser 28 into the steam turbine, and the steam turbine can be operated at the maximum operating point. . As a result, the steam turbine power generation equipment is always supplied with the maximum amount of steam that can be processed, and it is possible to perform maximum power generation.

In the above embodiment, the present invention is applied to a steam turbine power generation facility, but the present invention is not limited to this.
Obviously, the invention can be similarly applied to a blower plant in which a blower is rotated instead of the generator 24 according to FIG.

[0029]

According to the present invention, the maximum amount of steam that can be supplied to the steam turbine can always be supplied, and the steam turbine can be operated at the maximum operating point. Therefore, it is possible to maintain the amount of power generated by the power plant and the amount of air blown by the blowing plant to the maximum.

[Brief description of the drawings]

FIG. 1 is a system diagram showing the overall configuration of a steam turbine power plant to which the present invention is applied.

FIG. 2 is a system diagram showing a control system of a steam turbine power plant to which the present invention is applied.

[Explanation of symbols]

 Reference Signs List 22 steam turbine 24 generator 28 condenser 32 valve governor 40 turbine inlet steam flow transmitter 42 turbine inlet steam flow controller 51-53 extraction air flow transmitter 56 adder 58 … Bleed flow correction calculator

Claims (4)

[Claims] 1. A method for controlling a steam turbine in which steam is extracted from a middle stage of a steam turbine, wherein a flow rate of bleed air from the middle stage of the steam turbine is measured, and a set value of turbine inlet steam flow control is corrected using the measured value. A method for controlling a steam turbine, characterized in that the maximum steam amount that can be supplied to the steam turbine is always supplied. 2. The steam flow control according to claim 1, wherein the flow rate of the extracted air from each of the middle stages of the steam turbine is measured, and the total value is corrected by a linear function to obtain a correction value. A control method for a steam turbine, characterized in that the control value is added to a set value of the steam turbine. 3. The correction coefficient of the linear function according to claim 2, wherein the turbine inlet steam flow rate is manually changed, the turbine rotation speed is kept constant, and the turbine inlet steam flow rate and turbine bleed air flow rate data at that time are maintained. A method for controlling a steam turbine, wherein the method is performed by performing a first-order regression. 4. A steam turbine control device adapted to extract steam from a middle stage of a steam turbine, wherein a turbine inlet steam flow rate measuring means for measuring a turbine inlet steam flow rate, and the steam flow rate is measured by the turbine inlet steam flow rate measuring means. Turbine inlet steam flow rate, a turbine inlet steam flow rate adjusting means for controlling the turbine inlet steam flow rate in accordance with a deviation from the set value, a bleed air flow rate measuring means for measuring a bleed air flow rate from each stage of the steam turbine middle stage, Adding means for adding a bleed air flow rate measured by the bleed air flow rate measuring means to obtain a total value; correcting the total value by a linear function to obtain a correction value; and correcting a set value of the turbine inlet steam flow rate adjusting means. A control device for a steam turbine, comprising: a bleed air flow rate correction calculating means for supplying a maximum amount of steam that can always be supplied to the steam turbine.