JPH02169918A - Air flow rate control device - Google Patents

Abstract

PURPOSE:To keep the combustion state stable as well as prevent the generation of unburnt matter by compensating the leak from a nonoperating burner and the increased portion of the leak air from an extinguished burner and supplying air for combustion burners of a burner group. CONSTITUTION:Leak air volume from unoperating burners can be created by a function generator 18 on the basis of the differential pressure signal detected by a furnace/wind box differential pressure detector 17. Then, a total signal of leak air volume of a burner group is produced by multiplying the leak air volume by the signal 16 of the number of nonoperating burners by means of a multiplier 19. The total signal of leak air volume is sent to an adder 13 to be added to the signal of necessary combustion-air flow rate in accordance with the fuel flow rate. The difference between this signal and the output of a detector 15 of air flow rate supplied to the burner group is created by a subtracter 14, and this deviation signal is converted to the operating signal of damper opening by a proportional integrator 20 in order to adjust an adjusting damper 22 through an automatic/manual operation switcher. In this way, the shortage of air for combustion of burners during combustion is prevented, and the optimum state of combustion is always maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an air flow control device that divides a plurality of burners into at least two or more burner groups and has an air flow rate adjusting damper for each burner group.

[Conventional technology]

Figure 3 shows a diagram of the ventilation system around the burner.
The figure shows a cross-sectional view taken along line A-A.

The burner 6 is vertically divided into multiple stages (1 to n-1) and horizontally divided into multiple stages (four divisions) as shown in FIG. 4. In this figure, three burners 6 and one An example in which there are 4×n combinations with the air flow rate adjusting damper 4 will be explained.

Each air flow rate adjusting damper 4 is basically controlled to supply the air necessary for burning the target burner 6 in accordance with the amount of fuel input to the burner 6 .

In the figure, l is a forced draft fan, 2 is an air preheater, and 3 is a forced draft fan.
is an air flow rate detector, 5 is an air shutoff damper, 7 is a furnace, and 8 is a wind box.

[Problem to be solved by the invention]

However, in the above control method, if there is a burner 6 that is inactive among the three burner groups, the air flow rate leaking from the inactive burner 6 is not supplied to the burner 6 that is actually burning, so when the actual fuel is input. There were problems such as insufficient combustion air for the amount of combustion and unstable combustion.

In addition, regarding this type of device, Utility Model Application No. 56-
119344 etc.

An object of the present invention is to add the air flow rate leaking from idle burners to the air flow rate necessary for combustion in proportion to the number of idle burners in the above-mentioned combustion air flow rate adjustment device for a plurality of burner groups. The purpose is to create an air flow rate request signal and control the air flow rate based on this signal.

[Means to solve the problem]

For the above purpose, let α be the amount of leakage from the number of idle burners in the same air adjustment W/B (α can be expressed as a function of the furnace/W/B differential pressure), and let J be the number of idle burners. J×
Since α enters the furnace without contributing to combustion, this is achieved by adding J×α to the combustion air flow rate signal and controlling the air flow rate control damper.

[Effect]

The air flow rate adjustment damper supplies extra air flow leaking from the idle burner, so the required air to the burner during combustion is stably supplied without too much or too little, so there is no reduction in combustibility due to lack of air. This will solve the problem of fuel generation.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. still,
The ventilation system diagram around the burner is exactly the same as in Figures 3 and 4.

FIG. 1 is a system diagram of an air flow rate control device according to one embodiment of the present invention, and FIG. 2 is a system diagram of the same according to another embodiment.

In FIG. 1, first, an air flow rate signal is created by a function generator 12 to obtain a necessary air ratio with respect to a detection signal by a fuel flow rate detector 11, and based on this, an air flow rate signal for combustion is supplied to a plurality of burner glues. Air is controlled.

On the other hand, the amount of leak air from the burner that is inactive is determined by the furnace/wind box differential pressure detector 1 in the wind box.
function generator 18 for the differential pressure signal detected by 7.
By multiplying this signal by the number signal 16 of burners inactive using the multiplier 19, it becomes the total leak air amount signal for the burner group, and by sending this signal to the adder 13, it corresponds to the fuel flow rate. is added to the required combustion air flow signal. The difference between this signal and the air flow rate detector 15 supplied to the burner group is created by the subtractor 14, and this deviation signal is sent to the proportional integrator 2.
0, it is converted into a damper opening operation signal, and the adjustment damper 22 is adjusted via the automatic manual switch 21.

In the above configuration, the flow rate of combustion air is supplied to the burner group by correcting the amount of leak air from the burner while it is not in use, so the combustion state may deteriorate due to the lack of combustion air in the burner during combustion due to the leak air. Optimum combustion conditions are always maintained without deterioration.

Another embodiment of the invention is shown in FIG.

The basic circuit configuration is the same as that in FIG. Generally, when a burner is extinguished, the air shutoff damper (air register damper, etc.) closes at a slower rate than the closing speed of the burner inlet valve. The amount of air flowing into increases. on the other hand,
Since the air flow signal is created by the fuel flow rate, when the burner inlet valve closes, the air flow rate will decrease by the amount of the idle burner, but as the damper is not yet closed as described above, the leak air will cause more combustion than necessary. There will be a shortage of air. Therefore, in this embodiment, even when the burner extinguishing operation is started, the rate of change limiter 23 is added to restrict the air flow rate in response to changes in the air-side shutoff damper, thereby stabilizing the burner during combustion. It measures the

〔Effect of the invention〕

According to the present invention, in an air flow control device having n air conditioning devices for a plurality of burner groups, it is possible to compensate for leakage from idle burners in the group, increase in leakage air when burners are extinguished, etc. Since it is possible to supply air for the combustion burners of the burner group, and an appropriate air ratio can always be maintained, it is possible to maintain a stable combustion state. Further, since the operation can be performed with load changes without deteriorating the combustion state, it is possible to prevent the generation of unburned substances.

[Brief explanation of the drawing]

Fig. 1 is a system diagram of an air flow control device according to one embodiment of the present invention, Fig. 2 is a system diagram of the same according to another embodiment, and Fig. 3 is a general ventilation system diagram around a burner. Figure 4 is A-A.
FIG. 11...Fuel flow deposit detector, 12...Function generator, 1
3...Adder, 14...Subtractor, 15...Air flow rate detector, 16...Number of idle burners, 17...Furnace/wind box differential pressure detector, 18...Function generation device, 19... multiplier, 20... proportional integrator, 21...
・Automatic manual switch, 22...adjustment damper. Diagram

Claims (1)

[Claims] In an air flow control device that supplies combustion air to a burner group consisting of a plurality of burners using one air flow adjustment damper, there is provided a means for adding up the air flow rate leaking from a burner that is not burning in the burner group, An air flow rate control device comprising means for creating an air flow rate request signal to a flow rate adjustment damper and adjusting air supplied to the remaining burners during combustion.