JPS63217104A - Economizer steaming preventive controller - 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 [Industrial Application Field] The present invention relates to a steaming prevention control device for a steam saver applied to automatic control of transformer once-through in a thermal power plant.

[Conventional technology]

Conventionally, in the l@4 diagram, the function generator 2 receives the power generation amount command (
MM)) Create the main steam pressure setting signal by inputting
There is a system in which this is input to the first-order delay element (60 seconds) 5 in the entire load range, and the resulting main steam pressure setting signal 7 is used to control a variable voltage commutation boiler. In such a configuration, the following configuration is adopted as a measure to prevent steaming of the economizer (hereinafter referred to as ECO).

Normal water supply flow rate control is (boiler input demand signal) (BI
D) 27 and the actual water supply flow rate t22 are added in an adder 23, and the deviation signal thereof is inputted to a condenser 24, so that a water supply flow rate command signal 25, which is an output from this, is given to the operating end. .

On the other hand, as an ECO steaming monitor, a temperature deviation signal is calculated by a subtractor 12 from a signal generated by a function generator 10 that generates a saturation temperature by multiplying the ECO outlet feed water concentration I3 and the ECO rising water feed water pressure signal 11. is corrected by the adjuster 26 and input to the adder 23.

In such a configuration, if the sum temperature of the ECO Ichiji water supply pressure 1 and the ECO Ichiji water supply water temperature 13 become low, the correction signal of the regulator 26 is added by the adder 23, and the result is The water supply command signal is temporarily increased 5, which is intended to contribute to raising the ECO water supply temperature 13.

[Problem that the invention seeks to solve]

Conventionally, variable pressure once-through boilers have been operated under DSS and WS3 with high load change rates. In this process, in the low load area when the load decreases from the high load area to the low load area, in order to reduce the load 15 at a high rate of change as shown in Figure 2, the ECO output and water supply pressure are lowered by 1 no. For speed, E
The CO outlet feed water temperature 13 has a slow temperature drop rate due to the residual heat of the boiler. Therefore, the difference between the ECO output water supply pressure 1 sum temperature 16 and the ECO output water supply water temperature 13 degrees becomes smaller, and the amount of water supplied temporarily increases, but the effect does not appear immediately because the temperature time constant is long. Furthermore, depending on the settings of the regulator 26, there is a drawback that disturbance factors such as main steam pressure, main steam temperature, etc. may occur due to changes in the amount of water supplied.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a control device for preventing steaming of a steam saver, which has a tolerance for the temperature difference between the ECO outlet water supply temperature and the saturation temperature of the ECO outlet pressure, and is capable of preventing steaming of the steam saver. shall be.

[Means for solving problems]

In order to achieve the above object, the present invention generates a main steam pressure setting signal using a function generator that uses a function generator to control the boiler, and is provided in parallel on the upstream side of the boiler. Large and small first and second primary delay elements are provided between the first and second delay elements and the function generator. A switching means for switching to the next lag element and switching to the second first lag element in a state other than a load drop state, and a saturation temperature and the economizer outlet water supply based on the outlet water supply pressure of the economizer provided on the downstream side of the boiler. It consists of means for detecting the difference between the temperature and the main steam pressure setting signal and holding the main steam pressure setting signal when the detected value becomes equal to or less than a predetermined value.

[Effect]

By configuring the present invention as described above, the pressure drop is alleviated since the time of the first-order delay element becomes long in a load drop state of 50% load or less. Furthermore, when the temperature difference between the water supply temperature at the outlet of the economizer and the saturation temperature depending on the water supply pressure at the outlet of the economizer becomes small, the main steam pressure setting signal is held to prevent the temperature difference from becoming small. Therefore, the economizer steaming can be prevented.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a professional diagram showing an embodiment of the present invention.
The function generator 2 inputs the output command (detachment) 1, creates a main steam pressure setting signal, and transmits this to the primary delay element (60 seconds) 5 or the primary delay element via the changeover switch 3 or 4. (12
0 seconds) 6, and the main steam pressure setting signal 7 is output from the primary delay element 5 or 6.

The changeover switch 3 is used to switch the first-order delay element 5 to 6 when the output signal of the AND circuit 8 is ON, that is, when the load is 50% or less and the load is not increasing, and when the load is decreasing. be. The changeover switch 4 is switched when an output signal (set signal) B from the flip f70f9 described below is generated. That is, function generator 1
0, the saturation temperature is created by inputting the economizer outlet water supply pressure (in the figure, it is the ECO rising water supply pressure) 11. The subtractor 12 inputs the saturation temperature created by the function generator 1° and the economizer outlet water supply temperature (N13, which is the ECO sunrise water supply temperature in the figure), subtracts the two, and then switches the monitor switch (H/ L) A reset signal is output when the temperature difference resulting from the subtraction in step 14 is α°C or more, and a set signal is output when the temperature difference resulting from the subtraction is less than 1°C.

With this configuration, when the subtraction result of the subtracter 12 becomes 1°C or less, the changeover switch 4 is switched by the flip 70 f9 signal B, and the first-order lag element 5 is turned off. Also, the main steam pressure setting signal is held until the subtraction result of the subtracter 120 becomes α0 or more. Therefore, ECO steaming can be prevented.

This will be explained below with reference to FIGS. 2 and 3. Fig. 2 is for explaining the operation of the conventional device. In a variable pressure boiler, when the load 15 drops, due to variable pressure operation, the boiler pressure (ECO supply water pressure 16
As the ECO outlet pressure decreases, the saturation temperature 16 of the ECO outlet pressure decreases, whereas the ECO outlet feed water temperature 13 causes a time delay in decreasing due to the residual heat of the boiler.
The ECO rising water supply temperature is 13 degrees and approaches the saturation temperature 16 times.

On the other hand, as shown in FIG. 3, the device of the present invention has a load of 15
1 of the main steam pressure setting signal when falling (load 50% or less)
2 By switching to 120 seconds based on the dynamic characteristics, the drop in boiler pressure (ECO output water supply pressure 11) is alleviated, and the drop in the saturation temperature 16 of that pressure (ECO outlet pressure) is also reduced. Since there is no time delay between the ECO outlet water supply temperature 13 and the lower side, a margin of ΔT is created between the saturation temperature 16 and the ECO outlet water supply temperature 13, and the two do not approach each other. As a result of experiments on this matter, it has been confirmed that the temperature difference tolerance has increased by +5 to 6 degrees Celsius compared to the conventional device.

Note that since the water supply flow rate control is the same as the conventional device described above, the explanation thereof will be omitted here.

〔Effect of the invention〕

According to the present invention described above, the first-order delay of the main steam pressure setting signal is switched in two stages, and the main steam pressure setting signal is temporarily held at the temperature difference between the economizer feed water temperature and the saturation temperature. Therefore, it is possible to provide a control device for preventing steaming of the economizer, which has a margin for temperature difference and can prevent steaming of the economizer.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the steaming prevention control device for a economizer according to the present invention, FIGS. It is a block diagram showing an example of the steaming prevention control device of the economizer. Applicant's agent Patent attorney Takeshi Suzue 2 Figure 2
Third [4

Claims (1)

[Claims] In a system that uses a function generator to create a main steam pressure setting signal based on the power generation command, and controls the boiler based on this signal,
First and second primary delay elements of large and small sizes are provided in parallel on the upstream side of the boiler, and between the first and second delay elements and the function generator, the load When the load drops below 50%, it switches to the first primary delay element,
In addition, in a state other than a load drop state, the switching means switches to the second primary delay element, and detects the difference between the saturation temperature based on the outlet water supply pressure of the economizer installed downstream of the boiler and the temperature of the water economizer outlet water supply. and means for holding the main steam pressure setting signal when the detected value becomes less than or equal to a predetermined value.