JPH0413001A - Method for controlling steam temperature - Google Patents

Abstract

PURPOSE:To facilitate the control in a system with a plurality of dampers by determining the sum of the openings of all the dampers or the opening of a specially fixed damper on the basis of the value of the boiler load univocally and by adjusting the openings of specific dampers in such a way as to control the outlet-steam temperatures of the individual units of equipment under control. CONSTITUTION:A function generator 19 receives a load signal 11s, W and outputs a signal 14s, A representing the sum of the damper openings. On the other hand, a damper 5-3 has its opening adjusted by a damper-opening signal 16s, A1 from a controller 18a, and similarly a damper 5-4 has its opening adjusted by a damper-opening signal 17s, A2 from a controller 18b. The opening of a damper 5-2 is adjusted by a damper-opening signal 15s, [A-(A1+A2)] outputted by an adder-subtractor 20. Thus, while the load on the boiler is met in its totality, the control maintains the outlet-steam temperature of the first-step reheater 15-3 and that of the second-step reheater 15-4 at their respective specified values.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a boiler steam temperature control method.

[Conventional technology]

The conventional method will be explained with reference to FIGS. 4 and 5.

As shown in FIG. 4, the gas in the boiler furnace 1 is divided into a superheater 2 and a reheater 8, and passes through each damper 5-2.5.
-8 and then mixed in the mixing device 6, and then discharged from the boiler outlet lower.

Conventionally, the opening degree of the damper 5-8 was controlled to maintain the reheated steam temperature of the reheater 8 at the rated value.

This damper opening degree program is as shown in FIG. As shown above, it is uniquely determined.

[Problem to be solved by the invention]

The conventional control method described above has the following problems.

(1) Conventionally, there was only one object to be controlled.If the rear flue of a reheat furnace is divided into three or more paths, and there are two or more objects to be controlled, the conventional method uses a damper. The opening degree becomes unstable.

(2) In the conventional method, the damper opening degree is uniquely determined, for example, in order to control the reheat steam temperature. For example, when it is desired to set the damper opening slightly open in order to suppress pressure loss on the gas side under a certain load, such control cannot be performed.

[Means to solve the problem]

The present invention takes the following measures to solve the above problems.

In other words, as a steam temperature control method, the rear flue section is divided into multiple paths, and the amount of gas flowing through each path is changed by changing the opening degree of the damper installed in each path. In a boiler that controls temperature and reheat temperature M, the sum of all damper opening degrees or a certain damper opening degree is uniquely determined based on the boiler load value, and the predetermined damper opening degree is determined by each damper opening degree. Adjust to control the outlet steam temperature of the controlled equipment.

[Effect]

With the above means, for example, when the path in the rear flue section is divided into three and there are two objects to be controlled, the sum of three damper openings or one damper opening is determined based on the boiler load value. , the two damper opening degrees for the controlled devices are determined to control the outlet steam temperature of each controlled device. In this way, the opening degree of each damper is adjusted so as to correspond to the boiler load and to control the outlet steam temperature of the equipment to be controlled.

〔Example〕

An embodiment of the method of the present invention will be described with reference to FIGS. 1 to 3 in the case where there are three flue paths. In FIG. 1, the flue of the boiler furnace 1 is divided into three, and a superheater 2, a recuperator rG3, and a two-stage reheater 4 are provided in each path. In addition, these wakes are each damped by a damper 5-2.
．． It is connected to the mixer 6 via 5-3.54. In the figure, 7 indicates the boiler outlet. In the above configuration, as shown in FIG. 2, each damper 5-25-
3.5-4. Damper opening degree A1. The sum A of Ax and As is determined, and - the damper 5 for the role reheater 3 and the two-stage reheater 4
-3.5-4, the opening degree thereof is controlled and adjusted so as to maintain the outlet steam temperature of the first-stage reheater 3 and the outlet steam temperature of the second-stage reheater 4 at predetermined values.

FIG. 3 shows a block diagram of a control system that automatically performs the above method. - Deviation signal 12s of steam temperature at the outlet of the recuperator 3
is sent to the damper 53 via the controller 18a. Further, a deviation signal 13s of the outlet steam temperature of the two-stage reheater 4 is sent to the damper 5-4 via the controller 18b. Furthermore, the load signal IIs is a function generator F;
Electricity is input to. The adder/subtractor 20 further includes a controller 1
The outputs of 8a and 18b are inputted with reduced voltage and their own output is sent to the damper 5-2.

In the above configuration, as described above, the function generator 19 receives the load signal 11s, W and outputs the sum signal 14s, A of the damper opening shown in FIG. On the other hand, the opening degree of the damper 5-3 is set to iJJ by the damper opening signal 16s, A from the controller 18a. Similarly, the opening degree of the damper 54 is adjusted by the damper opening degree signals 17s and At from the controller 18b. Furthermore, the damper 5-2 receives the output of the adder/subtractor 20, the damper opening signal 15s, (A-(A++At)
) to adjust the opening degree. In this way, the load on the boiler can be met as a whole, and the load on the boiler can be met.
-3 and the outlet steam temperature of the two-stage reheater 15-4 are controlled and maintained at predetermined values, respectively.

According to this method, for example, when there are a plurality of boilers, it is possible to select an arbitrary combination of the sum of the damper opening degrees for each boiler load, that is, a combination at the designer's discretion.

In addition, above, a method was described in which the sum of the damper openings of all paths is specified by the boiler load, but this can also be done by specifying the damper opening of one path, for example, the opening of the damper 52, by the boiler load. However, the same effect can be obtained.

According to the above method, it is possible to control the objects in a case where there are two or more objects to be controlled and three or more means to control them in a very simple manner. Further, even when there is only one object to be controlled, the control conditions can be changed under different conditions. Furthermore, it becomes possible to set more optimal control conditions.

(Effects of the Invention) As explained above, according to the method of the present invention, the sum of the opening degrees of a plurality of dampers or a certain damper opening degree is determined according to the boiler load value, and the control target equipment The opening degree of each damper is controlled to maintain the outlet steam temperature at a predetermined value.In this way, control when there are multiple dampers becomes extremely easy.Also, more optimal control conditions can be achieved. You will be able to set it.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of one embodiment of the method of the present invention;
3 is a block diagram of the damper control system of the same embodiment. FIG. 4 is a system diagram of the conventional example.
The figure is an explanatory diagram of the operation of the conventional example. ■... Boiler furnace, 2... Heat exchanger 3...
-Reheater, 4...Two-stage reheater 5~2.5-
3.5-4...Damper. Agent: Patent attorney Akira Sakama and two others Figure 1

Claims (1)

[Claims] The rear flue section is divided into multiple paths, and the amount of gas flowing through each path is changed by changing the opening degree of the damper installed in each path, thereby controlling the main steam temperature and reheat steam temperature. In a boiler that operates, the sum of all damper openings or a specific damper opening is uniquely determined based on the boiler load value, and the predetermined damper opening controls the outlet steam temperature of each controlled device. A steam temperature control method characterized in that the steam temperature is adjusted as follows.