JP2002022163A - Method for controlling combustion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for controlling a combustion device capable of reliably generating a spark and reliably effecting ignition by keeping an ignition electrode in a constantly clean state. SOLUTION: A combustion device 2 has a spark type ignition device 7, and the spark type ignition device 7 is operated during waiting time of the combustion device 2.

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 a combustion device having a spark ignition device, and more particularly to a method for controlling a combustion device capable of maintaining spark performance of the spark ignition device.

[0002]

2. Description of the Related Art Combustion devices are provided as heating means for thermal equipment such as boilers and incinerators. Generally, a spark ignition device is used as an ignition device in this combustion device. The spark ignition device generates a spark by applying a predetermined AC voltage between two ignition electrodes or between one ignition electrode and a combustion device, and ignites fuel by the spark. It is configured as follows.

[0003] The above-mentioned combustion apparatus, particularly, the combustion apparatus using liquid fuel has the following problems. That is, in the combustion device, the liquid fuel from the fuel injection nozzle adheres to the tip of the ignition electrode,
The liquid fuel attached to the ignition electrode is heated by heat during combustion by the combustion device or residual heat after the combustion device is stopped, so that the film changes to a strong film. Further, the unburned portion of the liquid fuel also adheres to the ignition electrode as soot. Such dirt such as film and soot has high electrical insulation properties and is one of the factors that hinder the generation of sparks in the ignition device.

[0004]

The problem to be solved by the present invention is to keep the ignition electrode clean at all times.
An object of the present invention is to provide a control method of a combustion device that can reliably generate sparks and reliably perform ignition.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and the invention according to claim 1 is a control method for a combustion device having a spark ignition device, The spark type ignition device is operated when the combustion device is on standby.

Further, the invention according to claim 2 is a control method of a combustion device provided with a spark ignition device and a blower, wherein the amount of air blown from the blower is reduced when the combustion device is not burning. In this state, the spark type ignition device is operated.

[0007]

Next, an embodiment of the present invention will be described. The control method for a combustion device according to the present invention can be suitably performed in a combustion device having a spark ignition device, and can be particularly suitably performed in a combustion device used for thermal equipment such as a boiler or an incinerator. it can.

[0008] The combustion apparatus includes a fuel supply means,
The air conditioner includes a blower, a spark ignition device, and a controller for controlling these in accordance with predetermined control contents. First, the fuel supply means includes, for example, a fuel injection nozzle and a fuel supply line to the injection nozzle. The spark ignition device includes two ignition electrodes and voltage applying means between the ignition electrodes. The voltage applying means applies a high AC voltage between the ignition electrodes by using, for example, an ignition transformer. Here, the spark ignition device may be configured to use one ignition electrode by using a part of the combustion device as one ignition electrode, but in the following, two ignition electrodes are used. The configuration will be described.

The controller controls the fuel supply means, the blower, and the spark-type ignition device (hereinafter, referred to as an "ignition device"), and purges the interior of the thermal device prior to combustion, and a combustion device. And a post-purge step of purging the interior of the thermal device after the combustion is completed. Thus, the controller operates the blower during the pre-purge, combustion and post-purge phases.

[0010] Further, the controller operates the ignition device to perform an ignition operation over the period between the pre-purge stage and the combustion stage. In this ignition operation stage, a period from the start of the operation of the ignition device to the start of the operation of the fuel supply means is referred to as a "pre-ignition step". The interval is called the “ignition try stage”. The ignition of the fuel is performed in this ignition try stage. Here, in the following description, the pre-purge stage, the combustion stage, and the post-purge stage are collectively referred to as “during operation”. In addition, a state in which the entire combustion apparatus including the controller is stopped is referred to as “stop”, and a state other than the operation and the stop is referred to as “standby”.

[0011] In the control method of the combustion device according to the present invention, the ignition device is operated when the combustion device is on standby, that is, before the start of the pre-purge step or after the end of the post-purge step. Each of the ignition electrodes is cleaned. As described above, when the ignition device is operated at the time of standby of the combustion device, a strong spark can be generated at the tip end of each ignition electrode as compared with the preignition stage, and the energy of the spark allows Since dirt such as a film and soot is removed, each of the ignition electrodes can be reliably cleaned in a short time.

That is, if the wind speed between the ignition electrodes is high, only a weak spark is generated between the ignition electrodes, and if the wind speed is higher, no spark is generated. On the other hand, when the wind speed is low or not, a strong spark is generated. Therefore, as described above, when the ignition device is operated while the combustion device is on standby, that is, while the drive of the blower is stopped, there is no wind speed between the tips of the ignition electrodes. A stronger spark can be generated than in the preignition stage, and the energy of the spark removes dirt such as a film and soot, so that the ignition electrodes can be reliably cleaned in a short time. In addition, since the dirt attached to each of the ignition electrodes in the combustion stage can be removed while the combustion device is on standby, a spark can be reliably generated between the ignition electrodes during the next ignition operation. Therefore, reliable ignition can be performed.

Here, it is preferable that the cleaning of the ignition electrodes is performed as early as possible after the completion of the post-purge step. The reason will be described below. First, the controller terminates the post-purge step by outputting a stop signal to the blower.However, even if the fan of the blower receives the stop signal, it immediately loses its inertia due to its inertia. It does not stop but stops after gradually reducing the rotation. Therefore, between the time when the stop signal is output and the time when the fan stops, the ignition device is operated for a predetermined time to clean the ignition electrodes. More preferably, the ignition device is activated when a predetermined time elapses after a stop signal is output to the blower and the amount of air blown from the blower decreases by a predetermined amount. Then, since the amount of air blown from the blower is smaller than in the post-purge stage, and the wind speed between the ignition electrodes is also reduced, a strong spark is generated between the ignition electrodes and adheres to the ignition electrodes. It is possible to remove the stains in a short time. In addition, since a spark is generated between the ignition electrodes in a state where air is blown from the blower, even if unburned gas remains in the heating device, the unburned gas is generated by the spark. The danger of gas explosion can also be avoided.

Further, in the control method of the combustion device according to the present invention, the ignition device is operated in a state where the amount of air blown from the blower is reduced when the combustion device is not burning. That is, during the pre-purge stage (including the pre-ignition stage) or the post-purge stage, the amount of air blown from the blower is reduced for an appropriate time, and the ignition device is operated in this state, whereby Clean the ignition electrode. With such a control method, between the tips of the ignition electrodes,
As compared with the pre-ignition stage, a strong spark can be generated, and dirt can be surely removed in a short time.

Here, as described above, when cleaning the ignition electrodes, the amount of air blown from the blower can be reduced by reducing the amount of air blown by the blower itself. It is also possible to provide a blower volume adjusting means, for example, a damper, downstream of the blower, and to reduce the blower volume by using this damper. Further, in the case of using an air volume adjusting means such as the damper, the air volume can be reduced only between and around the ignition electrodes.

In the above description, the cleaning of the ignition electrodes is performed in a state where the air flow from the blower is reduced. In other words, the wind speed between the ignition electrodes is reduced. It is done in a state. That is, the wind speed between the ignition electrodes changes according to the amount of air blown from the blower. Therefore, when cleaning each of the ignition electrodes after the end of the post-purge step, it is preferable to operate the ignition device when the wind speed between the ignition electrodes becomes equal to or less than a predetermined value. Further, when cleaning each of the ignition electrodes when the combustion device is not burning, the amount of air blown from the air blower itself is reduced, or the amount of air blown from the air blower is adjusted by air flow amount adjusting means such as the damper. It is also preferable that the ignition device is operated in a state in which the wind speed between the ignition electrodes is decreased by decreasing the ignition speed.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is an explanatory view showing a schematic configuration of a first embodiment of the present invention, FIG. 2 is an enlarged explanatory view of an ignition electrode portion of FIG. 1, and FIG. 3 is a control content in the first embodiment. FIG. 4 is an explanatory diagram showing a time chart of FIG. Here, the first embodiment is an embodiment applied to a boiler as a heat device, and a combustion device in this boiler is a combustion device for liquid fuel. In addition, the combustion device in the first embodiment, for simplification of the description,
It is an on / off control type combustion device.

In FIG. 1, a combustion device 2 is provided above a boiler 1. This combustion device 2
The apparatus includes a liquid fuel injection nozzle 3 and a blower 4 for supplying combustion air. A fuel supply line 6 having a fuel valve 5 is connected to the injection nozzle 3.

Further, the combustion device 2 includes a spark ignition device (hereinafter, referred to as an "ignition device") 7. The ignition device 7 includes two ignition electrodes 8 and 8 and voltage applying means 9 between these ignition electrodes 8. Each of the ignition electrodes 8 has its tip end opposed to each other. It is attached to the combustion device 2 in a state where it is in a closed state.

Further, the combustion device 2 is provided with a controller 10 which is connected to each of the blower 4, the fuel valve 5 and the ignition device 7 via a line 11. . The controller 10 controls the combustion device 2 by controlling the blower 4, the fuel valve 5, and the ignition device 7 based on the steam pressure in the boiler 1, and controls the pre-purge stage and the combustion. Step and post-purge step are performed.

Next, the function of the controller 10 will be described.
This will be described with reference to FIG. First, when starting the combustion of the combustion device 2, the controller 10 first performs the pre-purge step. In the pre-purge stage, the blower 4 is operated to purge the inside of the boiler 1 prior to the combustion stage. Next, the ignition device 7 is operated and the fuel valve 5 is opened to inject fuel from the injection nozzle 3 to start the combustion stage. On the other hand, when stopping the combustion of the combustion device 2 and ending the combustion stage, the controller 10 closes the fuel valve 5 and stops the injection of the fuel from the injection nozzle 3. After the completion of the combustion step, the controller 10 performs the post-purge step. In the post-purge stage, by operating the blower 4 subsequent to the combustion stage,
The post-purge step is completed by purging the inside of the boiler 1 and outputting a stop signal to the blower 4 after a predetermined time has elapsed.

As shown in FIG. 3, the controller 10 performs an ignition operation step between the pre-purge step and the combustion step, and operates the ignition device 7 in this ignition operation step. Let it. Here, during the ignition operation stage, the fuel valve 5
Is called the "pre-ignition stage"
The period from the opening of the fuel valve 5 to the end of the operation of the ignition device 7 is referred to as an "ignition try stage". The ignition of the fuel is performed in the ignition trial stage.

In the following description, the pre-purge stage, the combustion stage, and the post-purge stage are collectively referred to as "operating". In addition, including the controller 10,
A state in which the entire combustion device 2 is stopped is referred to as “stop”, and a state other than the operation and the stop is referred to as “standby”.

The controller 10 is configured to clean the ignition electrodes 8 during the standby. That is, as shown in FIG. 3, after the end of the post-purge step, the ignition device 7 is operated for a predetermined time.
Specifically, at the end of the post-purge phase,
The controller 10 outputs a stop signal to the blower 4. The drive of the blower 4 is stopped by this stop signal, but the fan (not shown) of the blower 4 does not stop immediately due to inertia, but stops after its rotation gradually decreases. After a lapse of a predetermined time, when the rotation speed of the fan decreases and the amount of air blown from the blower 4 becomes equal to or less than the predetermined amount, the controller 10 outputs an operation start signal to the ignition device 7. . Then, the ignition device 7 is immediately activated by the operation start signal, and generates a spark between the ignition electrodes 8.

Then, the controller 10 keeps the ignition device 7 operated for a predetermined time until the fan stops. In this state, since the amount of air blown from the blower 4 is reduced and the wind speed between the ignition electrodes 8 is also reduced, a strong spark can be generated between the tips of the ignition electrodes 8. it can. Then, since the energy of the spark removes dirt such as a film and soot adhered to the tip of each of the ignition electrodes 8, it is possible to reliably clean the tip of each of the ignition electrodes 8 in a short time. it can. Therefore, in the next ignition operation stage of the combustion device 2, a spark can be reliably generated between the ignition electrodes 8, so that ignition of the fuel can be reliably performed.

Furthermore, since the cleaning of each ignition electrode 8 is performed after the post-purge step is completed and before the fan stops, the cleaning of each ignition electrode 8 can be performed safely. The reason is as follows. First, when the shut-off of the liquid combustion is incomplete due to the failure or deterioration of the fuel valve 5, the liquid fuel leaks from the injection nozzle 3 into the boiler 1, and this liquid fuel is May evaporate due to residual heat. In this case, with the fan stopped, the ignition device 7
Is activated, the vaporized liquid fuel is applied to each of the ignition electrodes 8.
Explosions can occur due to sparks in between. But,
As in the first embodiment, after the end of the post-purge stage and before the fan stops, even if the liquid fuel is vaporized in the boiler 1, the vaporized fuel is purged. Because of the state, the risk of explosion as described above can be avoided.

In the above description, the cleaning of the ignition electrodes 8 is performed after the end of the post-purge step, that is, when the combustion device 2 is on standby, but when the combustion device 2 is not burning, that is, the pre-purge step. In the middle or during the post-purge stage, the process can be performed with the amount of air blown from the blower 4 reduced. Next,
A second embodiment in which each of the ignition electrodes 8 is cleaned during the pre-purge step will be described with reference to FIG. FIG. 4 is an explanatory diagram showing a time chart of control contents and a change in the amount of air blow in the second embodiment of the present invention.

In the second embodiment, each of the ignition electrodes 8 is cleaned during the pre-purge step and before the pre-ignition step. In the second embodiment, a damper 12 as a blower amount adjusting means is provided downstream of the blower 4, and when cleaning the ignition electrodes 8, the damper 12 is squeezed by reducing the damper 12. The air volume has been reduced. Therefore, at the time of cleaning the ignition electrodes 8, since the wind speed between the ignition electrodes 8 is also low, a strong spark is generated between the tips of the ignition electrodes 8, and the energy of the sparks is increased. As a result, it is possible to reliably remove stains such as films and soot adhering to the tips of the ignition electrodes 8 in a short time. Therefore, at the time of the ignition operation performed following the cleaning of the ignition electrodes 8, the ignition of the liquid fuel can be reliably performed.

Further, a case where the ignition electrodes 8 are cleaned during the post-purge stage will be described. In this case, it can be performed in the same manner as in the second embodiment. That is, the damper 12 is located downstream of the blower 4.
When cleaning each of the ignition electrodes 8 during the post-purge stage, the damper 12 is throttled to reduce the amount of air to be blown. Also in this case, when cleaning each of the ignition electrodes 8, a strong spark is generated at the tip of each of the ignition electrodes 8, and dirt attached to the tip of each of the ignition electrodes 8 is reliably removed in a short time. be able to. Further, in this case, since each of the ignition electrodes 8 is cleaned during the post-purge step, the liquid fuel attached to each of the ignition electrodes 8 due to residual heat of the combustion device 2 and the boiler 1 is strongly. It is possible to prevent the formation of a natural film.

In the above description, the air flow from the blower 4 is adjusted by the air flow adjusting means such as the damper 12, but instead of providing such an air flow adjusting means, the blower 4 itself is adjusted. It can be performed by adjusting the amount of air to be blown. In this case, means for adjusting the rotation speed of the fan, such as inverter means, is provided.

[0031]

According to the present invention, the spark-type ignition device is operated when the combustion device is on standby, so that the ignition electrode of the spark-type ignition device can be reliably cleaned in a short time. Further, according to the present invention, the spark type ignition device is operated in a state where the amount of air blown from the blower is reduced when the combustion device is not burning. Can be reliably performed in a short time.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a schematic configuration of a first embodiment of the present invention.

FIG. 2 is an enlarged explanatory view of an ignition electrode portion of FIG.

FIG. 3 is an explanatory diagram showing a time chart of control contents and a change in air flow rate in the first embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a time chart of control contents and a change in a blowing amount in a second embodiment of the present invention.

[Explanation of symbols]

 2 Combustion device 4 Blower 7 Ignition device (spark ignition device)

Claims (2)

[Claims] 1. A method for controlling a combustion device 2 having a spark ignition device 7, wherein the spark ignition device 7 is operated when the combustion device 2 is on standby. 2. A method for controlling a combustion device 2 including a spark ignition device 7 and a blower 4, wherein the blower 4 reduces the amount of air blown from the blower 4 when the combustion device 2 is not burning. A method for controlling a combustion device, comprising: activating a spark ignition device.