JPS6126764Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a safety device for a combustor using a high limit switch.

[Conventional technology]

Conventional combustor burner controllers rely on signals from a safety circuit that shuts off the circuit when a high-limit switch or anti-seismic switch operates, and a combustion detection circuit that detects when the combustor can shift to stable combustion. This is to control valves, fan drive motors, etc. in an optimal manner, and various types have been proposed, including Utility Model Application No. 52-27642.

The main configuration of a safety circuit is generally a series connection of a reset switch, a self-holding relay, a high limit switch, or an anti-seismic switch, and a parallel connection of the contacts of the self-holding relay and the reset switch, and a combustion detection circuit. A common configuration is to detect the temperature of the combustion part as a temperature rise, and to detect the completion of preliminary combustion based on the temperature rise.

[Problem that the invention attempts to solve]

By the way, the high limit switch in the conventional safety circuit and the pre-combustion completion detector in the combustion detection circuit operate completely independently, and when the high-limit switch is activated, the pre-combustion completion detector is activated. It was thought that the high-limit switch would activate after the pre-combustion, but in rare cases, if abnormal combustion occurs during pre-combustion, there is a possibility that the high-limit switch will activate before the pre-combustion completion detector activates. In such a case, the safety circuit will act on the burner controller to cut off the power, so the fire will be extinguished with flammable gas or fuel remaining in the burner, and if the combustor is subsequently restarted, it will be extremely dangerous. There is a strong possibility that a deflagration phenomenon may occur.

[Means for solving problems]

This invention is intended to improve the above-mentioned problems, and the drawing is an overall diagram of an electric circuit of an embodiment of this invention, where A is a combustion detection circuit block, B is a safety circuit block, and C is a burner controller block. 1 is a pre-combustion completion detector constituted by a temperature switch; 2 is a relay connected in series with the pre-combustion completion detector 1; the relay 2 is made conductive by the pre-combustion completion detector 1;

4 is a reset switch, 5 is a self-holding relay,
Reference numeral 6 denotes a high limit switch that opens in the event of an abnormality, and the reset switch 4, self-holding relay 5, and high limit switch 6 are connected in series. Reference numeral 7 denotes a contact point of the self-holding relay 5, which is connected in parallel with the reset switch 4. 9 is an operation switch, 3 is a blower fan drive motor that supplies combustion air, 8 is a solenoid valve that opens and closes the fuel flow path to the burner, 11 is a switching solenoid valve that changes the flow rate of fuel flowing into the fuel flow path, and 10 is an ignition valve. Each electrical component is turned on and off in a sequence suitable for each burner.

12 is a contact point of relay 2 of the combustion detection circuit;
The blower fan drive motor of the burner controller is forcibly connected to a power source through a relay contact 12. Further, the high limit switch 6 uses a switching energization type, and a high limit contact that closes when an abnormality occurs is connected in parallel with the preliminary combustion completion detector 1.

[Effect]

A pre-combustion completion detector 1 consisting of a temperature switch detects the temperature of the burner, and when the burner ignites and rises to a certain temperature, the pre-combustion completion detector 1 is activated and the relay 2 is made conductive.

The safety circuit operates as follows: when the reset switch 4 is closed, the self-holding relay 5 is conductive and the contact 7 is closed; even when the reset switch 4 is opened, the self-holding relay 5 continues to be conductive, and the high limit switch 6 is activated. When this happens, the circuit will open.

The operation of the burner controller block in this embodiment is as follows: first, when the operation switch 9 is closed, the igniter 10, the solenoid valve 8, and the blower fan drive motor that supplies combustion air are energized, and the flow rate switching solenoid valve 11 is de-energized. A small flow rate suitable for ignition is flowing.
For this purpose, the burner is supplied with combustion air and fuel, and combustion is started by the igniter 10. The signal from the pre-combustion completion detector 1 switches the relay contact a-2 to stop the igniter 10 from energizing, and also switches the switching solenoid valve 11.
Since the burner is energized, the burner can perform combustion at a preset fuel flow rate.

To extinguish the burner, it is sufficient to open the operation switch 9, and the solenoid valve 8 stops the fuel to the burner.
Further, since the blower fan motor 3 is forcibly connected to the power source by the relay contact 12 of the pre-combustion completion detector 1, it continues to rotate for a while even after the operation switch 9 is opened, and the fire is extinguished normally.

Also, since the burner controller block is energized from the safety circuit, high limit switch 6
If activated, the fire will be extinguished in the same way as when the operating switch 9 is opened.

On the other hand, the high limit switch 6 is constructed of a switching energization type and is connected in parallel with the high limit contact that closes in the event of an abnormality and the preliminary combustion completion detector 1, so that the safety circuit is opened and the relay 2 is energized in the event of an abnormality. For this reason, even if the operation switch 9 is closed and the high limit switch 6 detects an abnormality before the completion of preliminary combustion, the blower fan motor 3 is forcibly connected to the power source and continues to rotate. The fuel continues to burn until the fire is extinguished and is discharged outside the burner as exhaust gas, and since the burner is not in a flammable atmosphere when restarted, no deflagration occurs.

〔effect〕

As mentioned above, conventional burners with a safety circuit using a self-holding relay were completely defenseless against abnormal combustion during the period from ignition to pre-combustion, but this invention is extremely capable of dealing with abnormal combustion during pre-combustion. This is a practical idea.

[Brief explanation of the drawing]

The drawing is an electrical circuit diagram of a combustor that can use this invented device. 1...Preliminary combustion completion detector, 2...Relay, 3
...Blower fan motor, 4...Reset switch, 5...Self-holding relay, 6...High limit switch, 7...Self-holding relay contact, 12...
relay contact.

Claims (1)

[Scope of utility model registration request] A safety circuit is constructed by connecting the reset switch 4, the self-holding relay 5, and the high limit switch 6, which opens in the event of an abnormality, in series, and connecting the contact 7 of the self-holding relay 5 and the reset switch 4 in parallel. 2 and a preliminary combustion completion detector 1 are connected in series to form a combustion detection circuit, the high limit switch 6 is of the switching energization type and has a high limit contact that closes in the event of an abnormality and a preliminary combustion completion detector. 1 are connected in parallel, and the blower fan motor 3 is directly connected to a power source via a relay 2 contact 12.