JPH0321809B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a combustion apparatus for an industrial furnace using gas fuel.

FIG. 1 shows a typical prior art. Gaseous fuel is premixed from a supply pipe 1 via an on-off valve 2, and combustion air is premixed from a pipe 3 via a flow control valve 4 in a bench lily mixer 5. This mixed gas is supplied from a pipe 6 to a burner 8 provided in an industrial furnace 7 . Gaseous fuel from line 1 and air from line 3 are mixed by another mixer 9 and fed to a pilot burner 10 for burner 8 . The temperature of the industrial furnace 7 is detected by a temperature detector 11. The control circuit 12 is
The opening degree of the flow rate control valve 4 is controlled so that the temperature inside the furnace detected by the temperature detector 11 is constant.

In such prior art, in order to supply a sufficient flow rate of the mixed gas to the burner 8, the diameter of the pipe line 6 must be increased, and this increases the risk of backfire.

An object of the present invention is to provide a combustion device for an industrial furnace that can prevent burners installed in the industrial furnace from backfiring to improve safety and can be downsized.

In the present invention, a solenoid valve 22 is interposed in the middle of a pipe line 21 that guides gas fuel from a gas fuel supply source, and combustion air at atmospheric pressure and gas fuel fed under pressure through the solenoid valve 22 are transported in a bench lily type. mixer 2
5, and the mixed gas from the mixer 25 is transferred to the regeneration pump 27.
The industrial furnace 37 is provided with a temperature detector 31 for detecting the temperature inside the industrial furnace 37.
A pressure detector is provided between the regeneration pump 27 and the burner 29 to detect the pressure of the mixed gas. 33, and when the pressure detected by the pressure detector 33 becomes less than a positive predetermined pressure value, the solenoid valve 22 is shut off.

FIG. 2 is a system diagram of one embodiment of the present invention. The gas fuel is passed from the pipe line 21 to the solenoid valve 22 which is an on-off valve.
is fed under pressure to a bench lily type mixer 25. Combustion air at atmospheric pressure is supplied to the mixer 25 from the pipe 23. The mixed gas from the mixer 25 is sucked through a line 26 by a regeneration pump 27 and supplied to a burner 29 through a line 28 . This burner 29 is attached to an industrial furnace 37. The temperature inside the industrial furnace 37 is detected by the temperature detector 31. This detected temperature signal is transmitted to the control circuit 32.
The rotational speed of the regeneration pump 27 is thereby controlled so that the temperature inside the furnace becomes a predetermined constant value. For example, when the temperature inside the furnace decreased, the control circuit 32 increased the rotational speed of the regeneration pump 27. This increases the flow rate of the mixed gas supplied to the burner 29. Furthermore, when the temperature inside the furnace rises above a predetermined temperature, the rotational speed of the regeneration pump 27 is reduced, thereby reducing the flow rate of the mixed gas to the burner 29. In this way, the temperature inside the industrial furnace 37 is kept constant.

The pressure of the mixed gas in the conduit 28 from the regeneration pump 27 is detected by a pressure detector 33. This pressure detection signal is given to the control circuit 34. The control circuit 34 keeps the solenoid valve 22 open when the pressure of the mixed gas in the pipe line 28 is a positive predetermined value, for example, 20 mmAq or more, and opens the solenoid valve 2 when the pressure becomes less than the predetermined value.
2 blocks it. This improves safety and
Backfire is reliably prevented.

An igniter 35 is provided for igniting the burner 29. This igniter 35 generates an ignition spark for igniting the burner 29. Thus, in this embodiment, the piping is simplified since the pilot burner 10 is not used as in the prior art described in connection with FIG.

The flow rate of the mixed gas by the regeneration pump 27 is set to a value of, for example, 30 m/sec or more during normal operation, thereby making it possible to reduce the diameters of the conduits 26 and 28, thereby making it possible to downsize.

Regeneration pump 27 is driven by, for example, an induction motor, and control circuit 32 includes an inverter for controlling the rotational speed of this induction motor.

The volume of the regeneration pump 27 is smaller than that of fans with other configurations, such as centrifugal fans.
Moreover, the pressure of the mixed gas discharged from the pipe line 28 can be made relatively high. Therefore, safety against flashback is improved, and the turndown ratio of the burner 29 can be increased.

In the embodiment described above, the flow rate of the mixed gas is controlled by the rotational speed of the regeneration pump 27, so the accuracy is high. In contrast, in the prior art described in connection with FIG. It is difficult to set the temperature inside the furnace to the desired value. The embodiments described above solve such problems.

As described above, according to the present invention, gas fuel and air are mixed in the mixer, and the mixed gas is sent under pressure to the burner by the regeneration pump, so that the mixed gas is transferred from the regeneration pump to the burner. The diameter of the pipe line for pressure feeding can be reduced, resulting in miniaturization. Furthermore, since the mixed gas is fed under pressure by the regeneration pump, safety against flashback is improved and the turndown ratio of the burner can be increased.

That is, in the present invention, the regeneration pump 27 is used to set the pressure of the mixed gas at about 200 to 1000 mmAq, and the mixed gas is transferred to the burner 2 at a relatively high pressure.
Moreover, the external size of this regeneration pump 27 can be reduced to about 1/10 of that of, for example, a centrifugal fan, and therefore the strength against flashback can be increased. As mentioned above, since the pressure of the mixed gas is high, the diameter of the pipe line 28 (see FIG. 2) that guides the mixed gas to the burner 29 can be reduced to improve explosion resistance.

Furthermore, according to the present invention, the pressurized mixed gas from the regeneration pump 27 can be easily guided not only to a single burner 29 but also to a plurality of burners in common.

Further, according to the present invention, the pressure-resistant combustion air and the gas fuel are introduced into the bench lily type mixer 25 through the solenoid valve 22, and the gas fuel is sucked by the regeneration pump 27. It is convenient that the air-fuel ratio can be controlled at a constant rate by setting the flow rates of each flow rate to the combustion air at the same ratio.

Furthermore, the pressure of the mixed gas between the regeneration pump 27 and the gas burner 29 is detected by the pressure detector 33, and the pressure detected by the pressure of the pressure detector 33 is a positive predetermined pressure. Solenoid valve 2 that supplies gas fuel when the value is less than the value
2, it is possible to more reliably prevent backfire from occurring.

This mixture of gas fuel and combustion air has properties that are completely different from those of only fuel such as gas or oil, and this mixture can be ignited by an ignition source such as a flame or spark. It ignites instantly and causes an explosion, and it is necessary to ensure safety against such explosions. In the present invention, the regeneration pump 27 is used to increase the pressure and supply it, and since the pressure is high, the regeneration pump 27
In this way, backfire is prevented by reducing the pipe diameter on the downstream side of Since the electromagnetic valve 22 for supplying gas fuel is shut off when the pressure becomes less than the pressure value, backfire can be prevented even more reliably.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of the prior art, and FIG. 2 is a system diagram of an embodiment of the present invention. 22... Solenoid valve, 25... Mixer, 27... Regeneration pump, 29... Burner, 31... Temperature detector, 33... Pressure detector, 37... Industrial furnace.

Claims (1)

[Claims] 1. A pipe line 2 for guiding gas fuel from a gas fuel supply source.
A solenoid valve 22 is interposed in the middle of the solenoid valve 1, and atmospheric pressure combustion air and gaseous fuel pumped through the solenoid valve 22 are guided to a bench lily type mixer 25, and the mixed gas from the mixer 25 is , regeneration pump 27
The industrial furnace 37 is provided with a temperature detector 31 for detecting the temperature inside the industrial furnace 37.
A pressure detector is provided between the regeneration pump 27 and the burner 29 to detect the pressure of the mixed gas. 33, and when the pressure detected by the pressure detector 33 becomes less than a positive predetermined pressure value, the electromagnetic valve 22 is shut off.