JP2876943B2 - Combustion control method at boiler startup - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion control method at the time of starting a boiler for preventing misfiring when the boiler is stopped for a long time, such as at night, and then restarted.

[0002]

2. Description of the Related Art After stopping a boiler for a long time, such as at night,
At the time of restart, misfire often occurs.
This is mainly due to the condensation of dew water on the ignited portion. That is, if the dew water adheres to the ignited portion, the spark does not occur at the correct place during the ignition trial, and is generated in another place short-circuited by the dew water, or the spark itself does not fly. .

[0003] In the case where non-ignition occurs due to the above-mentioned causes, in many cases, it is possible to smoothly shift to combustion by performing an ignition trial again. Therefore, in recent years, a combustion control having a recycle function has been adopted, in which a retry is performed when a misfire occurs. However, this combustion control with a recycling function is only used in oil-fired boilers, and in gas-fired boilers, the addition of a recycling function is not allowed for safety reasons.

[0004]

SUMMARY OF THE INVENTION The present invention provides
An object of the present invention is to provide a combustion control method at the time of starting a boiler, which can surely prevent non-ignition occurring when the boiler is stopped for a long time and then restarted, while ensuring safety.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problem, and measures the time from when the boiler is stopped to when the boiler is started again. When the time exceeds a preset time, at least one of a pre-purge operation and a pre-ignition operation accompanying a boiler start-up operation is performed by extending the normal set time.

[0006]

[Operation] The time from the operation of stopping the boiler to the operation of starting the boiler is measured again, and the measured time is compared with a preset value. When it is, start control for preventing misfiring is performed. That is, at least one of the pre-purge operation and the pre-ignition operation accompanying the start operation of the boiler is performed by extending the normal set time.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. The boiler (1) includes a heating burner (2), and combustion air is sent to the burner (2) by a blower (3). A fuel supply line (4) is connected to the burner (2), and a fuel pump (5) and a fuel valve (6) are inserted into the fuel supply line (4). The burner (2) is provided with a flame detector (7), and the presence or absence of a flame is detected by the flame detector (7).

The operation and stop of the burner (2) are controlled according to the load condition. That is, based on the signal from the pressure detector (8) that detects the internal pressure of the boiler, the combustion controller
According to (9), control is performed in accordance with a preset control procedure. If the internal pressure of the can exceeds the preset pressure value,
A stop instruction signal is sent to the burner (2), and a combustion instruction signal is sent to the burner (2) when the internal pressure of the can falls below a set value. A water level detector (10) for detecting the water level in the boiler can is connected to the side of the boiler (1) .Based on a signal from the water level detector (10), a water supply line (11 )
The feed pump (12) inserted inside operates ON-OFF,
The water level in the boiler can is kept at a certain level.

The determiner (13) is electrically connected to the combustion controller (9), and after stopping the boiler, again.
A function to measure the time until the boiler is started,
It has a function of comparing the measurement time with a preset value and a function of outputting a start control command signal for preventing misfiring when the measurement time exceeds the set value. As start-up control to prevent misfiring, the pre-purge operation and pre-ignition operation accompanying the boiler start-up operation are performed by extending the pre-purge operation from the normal set time or extending the pre-ignition operation from the normal set time. Or both the pre-purge operation and the pre-ignition operation are performed longer than a normal set time.

The operation of the present invention will be described below with reference to the above-described embodiment. FIG. 2 shows a comparison between the start control according to the present invention and the normal start control. In normal start control, a pre-purge operation of about 15 seconds is performed by the operation of the blower,
Next, for about 4 seconds, the ignition transformer (IGT) is activated and the fuel valve is opened, and an ignition attempt is performed. At this time, in the case of an oil-fired boiler, a pre-ignition operation (an operation in which the ignition transformer operates and only the spark flies before the fuel valve opens) for about one second is performed. The preignition operation of the gas-fired boiler is usually set to 0 seconds. This is because gas is superior in ignitability to oil.

Although three embodiments are shown as embodiments of the start-up control according to the present invention, the first embodiment is such that the pre-purge operation is performed longer than a normal set time. In the second embodiment, the pre-ignition operation is performed longer than a normal set time. In the third embodiment, both the pre-purge operation and the pre-ignition operation are performed by extending the normal set time.

Whether or not to perform these activation controls depends on the following determination procedure. First, in order to determine whether the boiler is restarted after being stopped for a long time, such as at night, the time from when the boiler is stopped to when the boiler is restarted is measured. . Then, the measured time is compared with a preset value, and when the measured time exceeds the set value, it is determined that a restart has been performed after a long stop, and the above-described method for preventing misfiring is performed. Start control. That is, at least one of the pre-purge operation and the pre-ignition operation accompanying the start operation of the boiler is performed by extending the normal set time. By doing so, even if dew water has adhered to the ignition portion, it can be sufficiently dried, and non-ignition can be prevented beforehand. When blowing air, it is more effective to send air heated by a heater.

[0013]

Since the present invention has the above-described structure, it is possible to reliably prevent non-ignition occurring when the boiler is stopped for a long time, such as at night, and then restarted, while ensuring safety. can do. Further, the present invention is also applicable to a gas fired boiler, and can use a common combustion control program for a gas fired boiler and an oil fired boiler.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an embodiment of a boiler to which the present invention is applied.

FIG. 2 is a time chart showing an embodiment of startup control in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Boiler 2 Burner 3 Blower 4 Fuel supply line 5 Fuel pump 6 Fuel valve 7 Flame detector 8 Pressure detector 9 Combustion controller 10 Water level detector 11 Water supply line 12 Water supply pump 13 Judgment device

Claims (1)

(57) [Claims] After performing a stop operation of a boiler, again
The time until the boiler start operation is measured, and when this measured time exceeds a preset time, at least one of the pre-purge operation and the preignition operation accompanying the boiler start operation is set to a normal setting. A combustion control method at the time of starting a boiler, wherein the combustion control method is performed for an extended period of time.