JPH05180574A - Device for controlling atmosphere inside furnace - Google Patents

Abstract

PURPOSE:To obtain a device for controlling the atmosphere inside a furnace which makes it easy to control flow-regulating valves for air and fuel gas and makes it possible to control the atmosphere minutely and is highly reliable. CONSTITUTION:To gas burners 2 attached to a kiln 1 air is supplied through an air-feeding line 21 and fuel gas, through a fuel gas-feeding line 23. In this fuel gas-feeding line 23 an equalizing valve 22 is provided. Loading pressure which can be removed from the air-feeding line 21 is channeled into a loading- pressure chamber at the equalizing valve 22 by a loading pressure-channel 27. With decrease of the pressure in the loading-pressure chamber, a diaphragms partitioning the inside of the housing of the equalizing valve 22 into the loading- pressure chamber and an atmospheric-pressure chamber increases the opening of the equalizing valve 22 by counteracting the force of a coil spring. Since the diaphragm functions to automatically control the air-fuel ratio between the air and the fuel gas, it is easier to initially set the opening of the respective flow-regulating valves for the air and the fuel gas.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discontinuous kiln, and more particularly to atmosphere control of a discontinuous kiln.

[0002]

2. Description of the Related Art Conventionally, when firing a ceramic body, it has been desired to properly control the atmosphere such as gas components, temperature and pressure in the furnace. This is because the change of the atmosphere in the furnace has a great influence on the quality of the product to be fired, such as the color and baking. As a control device for controlling the atmosphere in the furnace, a burner 2 is attached to the side wall of the kiln 1 as shown in FIG. 7, for example. Air from the blower blower 3 is supplied to the burner 2 according to the opening degree of the air damper 5 driven by the motor 4, and the fuel gas cylinder 7 is driven according to the opening degree of the fuel gas damper 9 driven by the motor 10.
The fuel gas whose pressure is reduced by the pressure reducing valve 8 is supplied to the burner 2. In the burner 2, air and fuel gas are mixed,
It is ignited as a mixed gas which is almost close to the theoretical air-fuel ratio, and the ignited high temperature combustion gas is blown out into the furnace.

[0003]

However, according to the conventional furnace atmosphere control device, since the operator manually adjusts the opening degree of the air damper and the opening degree of the fuel gas damper, the initial opening degree settings of both dampers are set. Since it is difficult to adjust the temperature and the opening degree in the middle, the work of adjusting the atmosphere in the furnace is complicated. If the opening degree of the adjusting valves such as two dampers is not proper, the atmosphere in the furnace becomes unstable due to excess and deficiency of air and fuel, resulting in uneven firing of the product to be fired and deterioration of the quality of the product to be fired. There is a problem.

The present invention has been made to solve such a problem, and facilitates the adjustment of the flow control valve for air and fuel gas, and has a highly reliable furnace atmosphere capable of precise atmosphere control. An object is to provide a control device.

[0005]

A furnace atmosphere control device according to a first aspect of the present invention for achieving the above object is a gas burner attached to a furnace body, an air passage for supplying air to the gas burner, and A fuel gas passage for supplying a fuel gas to the gas burner, a valve body of a flow rate control valve for opening and closing the fuel gas passage, a biasing means for biasing the valve body of the flow rate control valve in a closing direction, and an air passage from the air passageway. A diaphragm that divides a taken-out loading pressure into a loading pressure chamber that introduces it through a loading pressure introduction passage and an atmospheric pressure chamber that introduces atmospheric pressure, and resists the urging means as the pressure in the loading pressure chamber decreases. A diaphragm for driving the valve body in a direction of increasing the opening degree of the flow rate control valve.

The in-furnace atmosphere control device of the first aspect of the present invention can be provided with a loading pressure relief control valve for controlling the loading pressure in the loading pressure introduction passage, and controls the opening of the loading pressure relief control valve. An air-fuel ratio controller can be provided.

[0007]

According to the in-furnace atmosphere control device of the present invention, since the mixing ratio of air and fuel gas is automatically controlled by the diaphragm means, the initial setting work of the opening of the air flow control valve and the fuel gas flow control valve is performed. Will be easier.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. An embodiment in which the present invention is applied to a shuttle kiln is shown in FIG.
And shown in FIG. A gas burner 2 and a temperature sensor 12 for detecting the temperature in the furnace chamber are provided on the side wall of the kiln 1. Air from the blower blower 3 passes through the air damper 5 and is supplied to the gas burner 2 from the air passage 21. Further, the fuel gas from the fuel gas cylinder 7 is supplied to the gas burner 2 from the fuel gas passage 23 through a pressure equalizing valve 22 as a flow rate control valve described later. In the gas burner 2, air and fuel gas are mixed, and this air-fuel mixture is combusted and becomes combustion gas, which is blown into the furnace chamber.

The amount of air supplied is controlled by the temperature controller 14. The motor 4 driven by a command from the temperature controller 14 adjusts the opening degree of the air damper 5. The supply amount of air is adjusted according to the opening degree of the air damper 5. The air-fuel ratio controller 16 controls the mixing ratio of air and fuel gas. That is, the loading pressure taken out from the air passage 21 is introduced into the loading pressure chamber 29 of the pressure equalizing valve 22 shown in FIG. The loading pressure in the loading pressure introducing passage 27 is controlled by the loading pressure relief valve 20 shown in FIG. The opening of the loading pressure relief valve 20 is adjusted by the motor 18 driven by the command of the air-fuel ratio controller 16.

As shown in FIG. 2, the pressure equalizing valve 22 is divided into a loading pressure chamber 29 and an atmospheric pressure chamber 31 by a diaphragm 26 inside the housings 24 and 25. A valve body 32 is provided at the tip of a rod 28 that is integrally attached to the diaphragm 26. The valve body 32 controls the flow rate of the fuel gas flowing through the fuel gas passage 23. At the rear end of the rod 28, a coil spring 30 presses the rod 28 in the closing direction in the direction of closing the valve element 32. As a result, the valve body 3
The position 2 is the pressure Px introduced to the loading pressure chamber 29.
And the sum of the set pressure of the coil spring 30 and the atmospheric pressure chamber 3
It comes to a position where the atmospheric pressure Po guided to 1 is balanced. Therefore, when the pressure Px in the loading pressure chamber 29 decreases as the air flow rate increases, the diaphragm 26 rises in FIG. 2, increasing the opening degree of the valve body 32 and increasing the fuel gas flow rate.

Next, the relationship between the output of the temperature controller and the air-fuel ratio is shown in FIG. Even if the output of the temperature controller changes, the air-fuel ratio is controlled to, for example, the stoichiometric air-fuel ratio. When the opening degree of the relief valve 20 is increased and the pressure Px introduced into the loading pressure chamber 29 is increased, the air-fuel ratio is increased. Figure 4
Shows the relationship between the output of the temperature controller and the air flow rate.
When the motor 4 increases the opening degree of the air damper 5 according to a command from the temperature controller 14, the flow rate of the air flowing through the air passage 21 gradually increases. The setting of the air flow rate is fixed or programmed in the temperature controller 14 at the position of the dotted line or the solid line shown in FIG.

FIG. 5 shows the relationship between the opening of the loading pressure relief valve and the fuel gas flow rate. When the opening degree of the loading pressure relief valve 20 increases, the pressure Px in the loading pressure introducing passage 27 increases. Then, as shown in FIG. 2, as the pressure Px of the loading pressure chamber 29 increases, the opening degree of the valve body 32 integrated with the diaphragm 26 becomes smaller, so that the fuel gas flow rate gradually decreases.

FIG. 6 shows the relationship between the elapsed time during firing, the oxygen concentration in the furnace, and the temperature in the furnace. The oxygen concentration in the furnace is relatively high at the initial stage, but then gradually decreases and rises again immediately before the fire is stopped. The temperature inside the furnace gradually increases from the initial stage and reaches the maximum temperature immediately before the fire is stopped. After that, the temperature in the furnace gradually decreases. The in-furnace temperature characteristic and the in-furnace oxygen concentration can be appropriately changed according to the control programs of the temperature controller 14 and the air-fuel ratio controller 16,
The air flow rate and the fuel gas flow rate are controlled according to a time schedule based on the above-described operation based on a desired control program.

[0014]

As described above, according to the furnace atmosphere control device of the present invention, the fuel gas flow rate in the fuel gas passage is automatically controlled by the pressure equalizing valve which is the diaphragm means by the loading pressure introduced from the air passage. Therefore, it becomes easy to set the initial opening degree of the air flow rate control valve and the fuel gas flow rate control valve, and the workability of the control valve becomes good. Therefore, since the atmosphere control in the furnace chamber can be precisely controlled, there is an effect that the characteristics of the product to be fired such as color and tightness can be finished with high quality.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a furnace atmosphere control device according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing a pressure equalizing valve used in FIG.

FIG. 3 is a characteristic diagram showing a relationship between an output of a temperature controller and an air-fuel ratio.

FIG. 4 is a characteristic diagram showing the relationship between the output of the temperature controller and the air flow rate.

FIG. 5 is a characteristic diagram showing the relationship between the opening of the loading pressure relief valve and the flow rate of fuel gas.

FIG. 6 is a characteristic diagram showing the relationship between the elapsed time during firing, the oxygen concentration in the furnace, and the temperature in the furnace.

FIG. 7 is a circuit diagram showing a conventional furnace atmosphere control device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 kiln (furnace body) 2 gas burner 16 air-fuel ratio controller 20 loading pressure relief valve (loading pressure relief control valve) 21 air passageway 22 pressure equalizing valve (flow control valve) 23 fuel gas passageway 26 diaphragm (diaphragm means) 27 loading pressure introduction Passage 28 Rod (diaphragm means) 29 Loading pressure chamber 30 Coil spring (biasing means) 31 Atmospheric pressure chamber 32 Valve body

Claims (3)

[Claims] 1. A gas burner attached to a furnace body, an air passage for supplying air to the gas burner, a fuel gas passage for supplying fuel gas to the gas burner, and a valve body of a flow control valve for opening and closing the fuel gas passage. An urging means for urging the valve body of the flow rate control valve in a closing direction, a loading pressure chamber for introducing a loading pressure taken out from the air passage through a loading pressure introduction passage, and an atmospheric pressure chamber for introducing atmospheric pressure. And a diaphragm means for driving the valve body in a direction to increase the opening degree of the flow rate control valve against the biasing means in accordance with the pressure drop of the loading pressure chamber. In-furnace atmosphere control device. 2. The in-furnace atmosphere control device according to claim 1, further comprising a loading pressure relief control valve for controlling a loading pressure in the loading pressure introducing passage. 3. The in-reactor atmosphere control apparatus according to claim 2, further comprising an air-fuel ratio controller that controls the opening of the loading pressure relief control valve.