JP2962541B2 - Ventilation pressure control device for ventilation line for multi-can boiler - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ventilation pressure control device for a ventilation line for a multi-can boiler, which combines and discharges combustion exhaust gas discharged from a multi-can boiler.

[0002]

2. Description of the Related Art When a plurality of boilers are installed and the number of operating boilers is controlled in accordance with a load, exhaust pipes for exhausting combustion exhaust gas generated in each of the boilers are provided through separate ventilation lines and joint ventilation lines. , And is exhausted outside from the collective exhaust pipe.
In the case of multi-can installation, the number of boilers to be burned changes according to the load, and some boilers are burning and some are not. When air is blown by a blower and combustion is performed in the boiler, the pressure in the boiler increases, and the pressure in the exhaust stack to which combustion exhaust gas is sent also increases, but the pressure in the boiler that does not perform combustion does not change. However, there has been a problem that the combustion exhaust gas flows backward through a boiler that does not perform combustion with a pressure difference. Further, when the number of combustion boilers changes, the amount of combustion gas also changes. When the change in the amount of combustion gas changes the pressure in the collective exhaust cylinder, the air-fuel ratio in the boiler shifts, resulting in poor combustion. Therefore, as shown in FIG. 2, as the number of installed boilers increases, the size of the exhaust stack is increased, and the pressure in the exhaust stack is maintained at no pressure to prevent backflow and poor combustion. Increasing the size of the exhaust stack raises the problem that equipment costs increase.

[0003] As a method of preventing backflow at the time of combustion stoppage,
It was conceivable to provide a ventilation prevention device that shuts off the flow of gas in the individual ventilation line of each boiler, but even in that case, the pressure in the exhaust stack fluctuates due to the amount of combustion exhaust gas that varies with the number of combustion units, and the air-fuel ratio Problems such as the generation of black smoke due to poor combustion due to the displacement remained.

[Problems to be solved by the invention]

An object of the present invention is to prevent combustion exhaust gas from flowing back to a stopped boiler without increasing the size of an exhaust stack, and to keep the air-fuel ratio of a boiler performing combustion constant. Another object of the present invention is to provide a ventilation line for a multi-can boiler capable of stabilizing combustion.

[0005]

[MEANS FOR SOLVING THE PROBLEMS] A plurality of boilers for performing combustion by introducing combustion air into a boiler by a blower and further introducing fuel into the boiler are installed, and the combustion exhaust gas from each boiler is collected into an exhaust stack. In the ventilation line of a multi-can boiler that exhausts after merging, in the individual ventilation line before reaching the collective exhaust tube, a ventilation prevention device that can block the flow of gas, downstream from the individual exhaust line connection part of the collective exhaust tube The boiler is provided with a flow control device for adjusting the flow rate of the combustion exhaust gas that has been joined to the boiler, and when the boiler has stopped combustion, the individual ventilation line of the boiler is cut off by a ventilation prevention device, and the flow control device of the collective exhaust cylinder By adjusting the flow rate of the combustion exhaust gas, the inside of the collective exhaust cylinder is maintained at a constant pressure.

[0006]

A ventilation prevention device for blocking the flow of gas is provided in the individual ventilation line of each boiler and closed when the boiler combustion is stopped, thereby preventing the backflow of the combustion exhaust gas. If the backflow of the combustion exhaust gas can be prevented, it is not necessary to maintain the pressure in the exhaust stack at no pressure, and a positive pressure may be used. Although it is difficult to keep the pressure at no pressure, to maintain a constant positive pressure, it can be implemented by a simple method of adjusting the flow rate of the combustion exhaust gas of the exhaust stack. By keeping the pressure positive, the pressure is kept constant and the combustion is stabilized.

[0007]

An embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows an outline of the present invention, in which a boiler A (1
A) ・ Boiler B (1B) ・ Boiler C (1C) The three boilers are blower A (8A), blower B (8B), blower C (8C), respectively.
And a combustion device A (9A), a combustion device B (9B), and a combustion device C (9C), and perform combustion by introducing combustion air and fuel into the boiler. The exhaust stack that exhausts the combustion exhaust gas generated by the combustion is provided with an individual exhaust pipe A (3A), an individual exhaust pipe B (3B), and an individual exhaust pipe C (3C) in each boiler.
Each individual exhaust pipe is connected to one collective exhaust pipe, and a ventilation line is provided from the blower to the boiler and the individual exhaust pipe to the collective exhaust pipe. A ventilation prevention device A (4A), a ventilation prevention device B (4B), and a ventilation prevention device C (4C) for shutting off the flow of the combustion exhaust gas by closing the blade are provided in each individual exhaust cylinder. Each ventilation prevention device is opened and closed according to the combustion state of each boiler, and ventilation prevention devices (4A) and (4B)
・ (4C) is the boiler controller A (6A) ・ Boiler controller B (6B)
Opening / closing is performed by a signal from the boiler control unit C (6C). Each exhaust stack (3A), (3B),
Downstream from the portion to which (3C) is connected, a flow rate adjusting device (5) for adjusting the opening by rotating the blades and adjusting the flow rate of the combustion exhaust gas is provided. The flow control device is connected to a pressure detecting device (7) for detecting the pressure in the collective exhaust tube, and controls the opening of the flow control device (5) so as to keep the pressure in the collective exhaust tube constant.

For example, boiler A (1A) and boiler B
When (1B) performs combustion, the boiler control units A (6A) and B
A boiler combustion signal is sent from (6B) to the ventilation prevention devices A (4A) and B (4B), the ventilation prevention devices A (4A) and B (4B) are opened, and the individual exhaust cylinders A (3A) and B (4B) are opened. The flow of the combustion exhaust gas in (3B) is made possible so that the combustion exhaust gas generated in the boiler can be exhausted. In addition, boiler C (1
C), a boiler stop signal is sent to the ventilation prevention device C (4), the ventilation prevention device C (4C) is closed and the individual exhaust pipe C (3C) is closed.
The flow of the combustion exhaust gas is shut off, and the backflow of the combustion exhaust gas is prevented. The pressure in the boiler performing combustion is increased by about 20 mmAq, and the pressure in the exhaust stack (2) is also increased by the combustion exhaust gas being fed. Collective exhaust stack
The amount of pressure rise in (2) differs depending on the amount of flue gas, and when the number of boilers performing combustion changes, the amount of flue gas also changes. Therefore, the opening degree of the flow control device (5) is adjusted, and the internal pressure of the collective exhaust pipe (2) is maintained at a set value of not less than 0 and less than the internal pressure of the boiler, for example, 10 mmAq. By keeping the pressure in the exhaust cylinder constant, each boiler can keep the air-fuel ratio constant, and can obtain stable combustion.

Since the pressure in the exhaust stack is determined by the amount of combustion exhaust gas, and the amount of combustion exhaust gas varies depending on the number of boilers burned, the flow control device (5) depends on the number of boilers burned. The same effect can be obtained by adjusting the opening degree of.

[0010]

According to the present invention, even in the case where multiple boilers are installed and the combustion exhaust gas is exhausted from the collective stack, there is no fear of the backflow of the combustion exhaust gas, and the combustion can be stabilized. Therefore, it is not necessary to increase the size of the exhaust stack, and the equipment cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an embodiment of the present invention.

FIG. 2 is a schematic diagram of a conventional case.

[Description of Signs] 1A, 1B, 1C Boiler 2 Collective Exhaust 3A, 3B, 3C Individual Exhaust 4A, 4B, 4C Ventilation Prevention Device 5 Flow Rate Adjuster 6A, 6B, 6C Boiler Controller 7 Pressure Detector 8A, 8B・ 8C blower 9A ・ 9B ・ 9C Combustion device

Claims (1)

(57) [Claims] 1. A plurality of boilers, which perform combustion by introducing combustion air into a boiler by a blower and further introducing fuel into the boiler, are installed, and the combustion exhaust gas from each boiler is exhausted after merging into a collective exhaust stack. In the ventilation line of a multi-can boiler, a ventilation prevention device that can shut off the flow of gas in the individual ventilation line before reaching the collective exhaust, combustion that merges downstream from the individual vent line connection of the collective exhaust A flow control device for adjusting the flow rate of the exhaust gas is provided, and when the boiler is stopping combustion, the individual ventilation line of the boiler is blocked by a ventilation prevention device, and the flow rate of the combustion exhaust gas is controlled by the flow control device of the collective exhaust cylinder. A ventilation pressure control device for a ventilation line for a multi-can boiler, wherein the inside of a collective exhaust cylinder is maintained at a constant pressure by adjustment.