JP3022250B2 - Blow control method for three-position combustion control 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 method for controlling the air flow of a boiler which adjusts the air flow by combining a blower whose rotational speed is adjusted and a damper which adjusts the air flow from the blower.

[0002]

2. Description of the Related Art In the case of a boiler performing three-position combustion control, the supply amount of combustion air is adjusted according to the fuel supply amount. In the past, the amount of air blown from a blower was constant, and the amount of air blow was adjusted by adjusting the degree of opening of a damper provided in the middle of the wind path. A method has been proposed in which the speed is adjusted and the air flow rate is adjusted. In the case of adjusting the rotation speed of the blower, when the rotation speed is reduced, the effect of reducing power consumption and noise can be obtained. Combining the adjustment by the blower rotation speed and the adjustment by the damper opening as described in, keep the blower rotation speed at a high combustion air flow rate from prepurge to ignition, first low combustion, first high combustion, and A method has been proposed in which the damper opening is set to the low combustion side only during the first low combustion after ignition.

[0003] Further, the boiler is controlled so that the combustion is started when the steam pressure is reduced. However, when the boiler starts the combustion, it is dangerous if there is an unburned mixed gas in the boiler. It is necessary to send a certain amount of air into the furnace and perform pre-purge to ventilate the furnace,
The start of combustion is delayed by that time. If the time until the start of the combustion becomes longer, the steam pressure is greatly reduced, and the followability to the load is deteriorated. Therefore, it is desired to start the combustion as soon as possible.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to reduce the pre-purge time and the time from when the steam pressure decreases until the start of combustion.

[0005]

Means for Solving the Problems In a boiler which has a blower whose rotation speed is adjusted and a damper which adjusts the amount of air flow from the blower, the combustion control is performed at three positions of high combustion, low combustion and stop. When the blower is operated, the rotation speed is set in three stages: the air volume for purge, the air volume for high combustion, and the air volume for low combustion. The opening of the damper is also adjusted to the high combustion opening and the low combustion opening. In advance, when the pre-purge is performed, the rotation speed of the blower is set to the purge air volume, the damper opening is set to the high combustion opening, and at the time of ignition, the opening of the damper is changed to the low combustion opening to perform ignition.

[0006]

[Function] It is necessary to adjust the amount of air to be blown during combustion so that appropriate combustion can be performed with respect to the amount of fuel supplied. However, since the purpose of pre-purge is to send a certain amount of air for ventilation, There is no need to limit the pre-purge, and the pre-purge time can be reduced if the pre-purge is performed with a purge air flow rate higher than the normal blower rotation speed. Using a powerful blower, setting the opening for purging at the opening of the damper, and controlling the ventilation volume with the damper even during high combustion can shorten the pre-purge time, but in this case the air flow from the blower other than pre-purge Is wasted. However, when the rotation speed is increased only during the pre-purge, no waste occurs, and only the pre-purge time can be reduced.

[0007]

An embodiment of the present invention will be described with reference to the drawings.
FIG. 1 relates to claim 1 and FIG. 2 relates to claim 2.
The upper part is a control chart of the fan rotation speed, the middle part is a control chart of the damper opening, and the lower part is a description of the operating state of the boiler. Burner combustion is controlled at three positions: high combustion, low combustion, and stop. At the start of combustion, prepurge is performed for ventilation in the furnace, and low combustion is performed until the flame stabilizes after ignition of the burner. High burn after being done. The rotation speed of the blower is set in addition to the stoppage, such as purge air flow, high combustion air flow, and low combustion air flow. Is set. The air volume at this time is the air volume for purging> the air volume for high combustion> the air volume for low combustion,
High combustion opening> low combustion opening.

A description will be given with reference to FIG. When the combustion of the burner is stopped, the rotation speed of the blower is stopped, and the damper opening is also fully closed. When the start of combustion is output, the blower rotation speed is set to the maximum air flow for purging and the damper opening is set to the maximum opening for high combustion. Sent into
Prepurge is completed in a shorter time than usual.

Since the change of the rotation speed of the blower takes a longer time than the change of the air volume by the damper, the change of the blower speed during the pre-purge before the time set for the pre-purge elapses.
An output to change the fan rotation speed to a high combustion air volume is performed.
When the time set as the prepurge time elapses, the blower rotation speed is changed to the high combustion air flow, and the damper opening is changed to the low combustion air opening, so that the air flow is reduced and ignition is performed. During the first low burn after ignition, the fan speed
Keep the damper opening as it is to stabilize the flame. When shifting the combustion to high combustion, the blower rotation speed is maintained at the high combustion air flow rate, the damper opening is increased to the high combustion air flow rate, and the air flow rate is increased. Maintain the high combustion position and adjust the fan speed according to the combustion condition.

When the boiler stops burning, a post-purge is performed. When the post-purge is completed, the blower is stopped and the damper is fully closed to prevent the boiler from cooling.

FIG. 2 is a chart in the air blowing control method according to the second aspect. FIG. 2 shows that the blower rotation speed is maintained at the purge air flow rate after ignition and after a low combustion period after the end of pre-purge, and the air flow at the time of ignition is stabilized by adjusting the air flow sent to the burner by the damper. . During the pre-purge, the rotation speed of the blower is set to the purge air volume, and the damper opening is set to the high combustion opening. After the elapse of the time set for the pre-purge, the opening of the damper is changed to the low-combustion opening while the rotation speed of the blower is maintained at the purging air volume, and ignition is performed. During that time, the rotation speed of the blower and the opening of the damper are maintained. Thereafter, when the combustion amount is changed from low combustion to high combustion, the rotation speed of the blower is changed from the air flow for purge to the air flow for high combustion, and the damper opening is changed from the opening for low combustion to the high combustion. Change to degree.

In these control methods, even if the output to the blower is changed from the purge air volume to the high combustion air volume at the time of ignition, it takes a long time for the actual air volume to change from the purge air volume to the high combustion air volume. This is effective for the problem that the air volume at the time of ignition is not stable.

[0013]

By implementing the present invention, the pre-purge time can be shortened, and the time from when the steam pressure decreases to the time when steam is generated is shortened, so that the load followability can be improved.

[Brief description of the drawings]

FIG. 1 is a control chart of an embodiment of the present invention.

FIG. 2 is a control chart of another embodiment of the present invention.

Claims (2)

(57) [Claims] An air blower whose rotation speed is adjusted and a damper which adjusts the amount of air flow from the air blower have a high combustion performance.
In a boiler in which combustion control is performed at three positions of low combustion and stop, the rotation speed when the blower is operated is set to three stages of a purge air volume, a high combustion air volume, and a low combustion air volume, and the damper is opened. The opening degree for high combustion and the opening degree for low combustion are set in advance, and when performing pre-purge, the rotation speed of the blower is set to the air flow for purging and the damper opening is set to the opening for high combustion, and set to pre-purge. During the pre-purge before the time elapses, an output to change the fan rotation speed to a high combustion air volume is performed, the fan rotation speed is set to a high combustion air volume, and the damper opening is set to a low combustion air opening. An air blowing control method for a three-position combustion control boiler, wherein ignition is performed by changing the ignition. 2. It has a blower whose rotation speed is adjusted, and a damper which adjusts the amount of air flow from the blower, and has a high combustion and
In a boiler in which combustion control is performed at three positions of low combustion and stop, the rotation speed when the blower is operated is set to three stages of a purge air volume, a high combustion air volume, and a low combustion air volume, and the damper is opened. The opening degree for high combustion and the opening degree for low combustion are set in advance, and when performing pre-purge, the rotation speed of the blower is set to the air flow for purging and the damper opening is set to the opening for high combustion, and set to pre-purge. After the elapse of time, the opening speed of the damper is changed to the low-combustion opening while the blower rotation speed is maintained at the air flow for purging, and ignition is performed. When the combustion amount is changed from low combustion to high combustion for the first time after ignition, the rotation speed of the blower is changed from purge air flow to high combustion air flow, and the damper is opened. Degree from low combustion opening to high combustion opening 3 air blow control method positions combustion control boiler, characterized by.