JPH06317304A - Steam temperature controller with automatic bias circuit - Google Patents

Abstract

PURPOSE:To make possible the holding of the balance of an outlet steam temperature of 4-systems of superheaters automatically. CONSTITUTION:Metal temperatures of superheaters A1, A2, B1 and B2 are detected separately. Deviation signals 13A of the A1 and A2 are inputted into a PI controller 15A through a dead band 14A to obtain A1/A2 bias signals 8. The bias signals 8 are added to an opening command signal 5b to generate an opening command signal 16b while being subtracted from an opening command signal 5a to generate an opening command signal 16a. Thus, superheater spray control valves 1 and 2 controlled so that the opening thereof increases on the high temperature side to lover the metal temperature and it decreases on the low temperature side to raise the metal temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steam temperature control device using an automatic bias circuit, which is applied to a steam temperature control circuit of a boiler automatic control device.

[0002]

2. Description of the Related Art A conventional steam temperature control circuit is shown in FIG.
In this control circuit, 4 consisting of A1, A2, B1 and B2
Opening degree command signals 5a, 5b, 5c of superheater spray control valves 1, 2, 3, 4 provided for each superheater of the system,
By adding or subtracting the bias signals set by the superheater metal temperature bias setters 6 and 7 to 5d,
The balance of the outlet steam temperature of each system is controlled by manual operation. That is, the superheater metal temperature bias setter 6 sets the A1 and A2 bias signals 8 and adds or subtracts the bias signals to the opening degree instruction signals 5b and 5a to thereby set the superheater spray control valves 1 and A2 of A1. The opening degree of the superheater spray control valve 2 is controlled. Further, the superheater metal temperature bias setting device 7 receives the B1 and B2 bias signals 9
Is set, and the bias signal is added to or subtracted from the opening signals 5d and 5c to control the opening of the superheater spray control valve 3 of B1 and the superheater spray control valve 4 of B2. Reference numeral 10 denotes a superheater outlet temperature bias setting device, which can set an A / B bias signal 11 for the outlet temperature.

[0003]

By the way, in the above-mentioned conventional steam temperature control circuit, by manually operating each bias setting device, the balance of the outlet steam temperature of each system of A1, A2, B1 and B2 is made uniform. It was controlled to keep it at. As a result, the controllability is poor and there is the inconvenience that the operator needs to be skilled in the operation.

Therefore, an object of the present invention is to provide a steam temperature control device by an automatic bias circuit, which can automatically keep the balance of the outlet steam temperature of each system.

[0005]

The present invention is to solve the above-mentioned problems and is a control device for automatically controlling the steam temperature of a boiler, which is a four-system superheater consisting of A1, A2, B1 and B2. Of each of the four systems, the output signals obtained by respectively detecting the metal temperatures of the above and inputting the signals of the deviation between A1 and A2 and the deviation between B1 and B2 to the PI controller, respectively. Bias circuit for automatically biasing the steam temperature at the outlets of the four systems so that the temperature distribution of each superheater outlet becomes uniform by adding or subtracting a bias to the opening command of the reactor spray control valve Is a steam temperature control device.

[0006]

According to the above-mentioned means, a signal having a large transient deviation due to a dead band is removed from the signal obtained by subtracting the metal temperature of the superheater A1 from the metal temperature of the superheater A2, and the resulting signal is input to the PI controller. Create a superheater bias signal between and. This bias signal becomes a positive (+) A1 · A2 bias signal when the metal temperature of the superheater A2 is higher than the metal temperature of the superheater A1, and increases the opening degree of the superheater spray control valve (A2 system). And, it acts so as to reduce the opening degree of the superheater spray control valve (A1 system). As a result, the metal temperature of the superheater A1 rises and, conversely, the metal temperature of the superheater A2 falls,
As a result, the steam temperature difference between the A1 system and the A2 system becomes small, and the steam temperature imbalance is improved. Also, B1
The steam temperature difference between the system and the B2 system also acts in the same manner to improve the imbalance.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described with reference to FIG. Sensors are attached to the superheaters consisting of four systems of A1, A2, B1 and B2 to detect the superheater metal temperature. A plurality of superheater metal temperatures (for example, 6 points) are detected for one superheater, and the highest detected value is selected from among them to select the temperature signals 12a, 12b, 12c, 1 of the respective superheaters.
2d.

The A1 and A2 superheater system will be described below. The temperature signals 12a and 12b described above, that is, the temperature signal 12a of the superheater A1 and the temperature signal 12 of the superheater A2.
The difference (12b-12a) is calculated from b, and the deviation signal 1
Pass dead band 14A as 3A. This deviation signal 1
3A is sent to the PI controller 15A after the signal having a large deviation is transiently removed by the dead band 14A,
It becomes the 1 · A2 bias signal 8. In the present embodiment, when the metal temperature of the superheater A2 is higher than the metal temperature of the superheater A1, that is, when the temperature signal difference (12b-12a) is positive, the A1 · A2 bias signal 8 also becomes positive (+).

Bias signal 8 thus obtained
Is added to the opening command signal 5b for the superheater spray control valve 2 of the superheater A2, and is subtracted from the opening signal 5a for the superheater spray control valve 1 of the superheater A1. Therefore, if the A1 and A2 bias signals 8 are positive, the opening command signal 16b after the bias addition to the superheater spray control valve 2 changes in the direction of increasing the opening, so the spray injection amount increases and the superheater increases. Although the metal temperature of A2 decreases, the opening command signal 16a after the bias subtraction for the superheater spray control valve 1 changes in the opposite direction to decrease the opening, so the spray injection amount decreases and the superheater A1 Metal temperature rises. As a result, the steam temperature difference at the outlet of the superheater between both systems of the superheaters A1 and A2 becomes small, and the imbalance is automatically corrected. Further, if the A1 and A2 bias signals 8 are minus (-), the metal temperature of the superheater A2 is raised and the metal temperature of the superheater A1 is controlled to be lowered. The difference becomes smaller and the imbalance is automatically corrected.

The same control as that of A1 and A2 described above is performed between both systems of the superheaters B1 and B2.
3B is a deviation signal, 14B is a dead band, and 15B is a PI.
Controller, 9 is B1 and B2 bias signal, 16c,
Reference numeral 16d indicates the opening degree instruction signal after the bias addition or subtraction.

The deviation signal 17 between the superheater outlet temperature (A) and the superheater outlet temperature (B) is also sent to the PI controller 18 between the superheater A1 and A2 systems and the superheater B1 and B2 systems. By outputting the A / B bias signal 11, the balance between the two is controlled.

[0012]

According to the present invention described above, the superheater A1
When a difference occurs between the metal temperature of (or B1) and the metal temperature of the superheater A2 (or B2), the opening command signals for the respective superheat spray control valves undergo bias addition or subtraction according to the temperature difference. , The spray injection amount is increased or decreased to control the temperature difference automatically. Therefore, good controllability can be obtained, and the effect of facilitating the management of the steam temperature can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing a steam temperature control circuit according to an embodiment of the present invention.

FIG. 2 is a diagram showing a conventional steam temperature control circuit.

[Explanation of symbols]

5a, 5b, 5c, 5d Opening command signal 8 A1 · A2 bias signal 9 B1 · B2 bias signal 11 A / B bias signal 12a, 12b, 12c, 12d Temperature signal 13A, 13B Deviation signal 15A, 15B PI controller 16a, 16b, 16c, 16d Opening command signal (after bias addition / subtraction)

Claims (1)

[Claims] 1. A controller for automatically controlling the steam temperature of a boiler, which detects the metal temperatures of four superheaters consisting of A1, A2, B1, and B2, and detects the deviation between A1 and A2 and B1. Bias addition or subtraction of the output signal obtained by inputting the signal of the deviation from B2 to the PI controller to or from the opening command of the superheater spray control valve provided for each of the four superheaters, A steam temperature control device using an automatic bias circuit for automatically biasing the steam temperatures at the outlets of the four systems so that the temperature distributions at the outlets of the respective superheaters become uniform.