JPH0587731B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a combustion heating furnace used for various purposes such as firing ceramics, and more particularly, to a means for setting a pattern of change in furnace temperature over time; , a means for detecting the temperature inside the furnace is provided, and the state of fuel supply to the furnace heating burner and the oxygen for combustion are adjusted so that the temperature inside the furnace detected by the detection means changes over time in accordance with the change pattern set by the setting means. The present invention relates to a combustion heating furnace that is equipped with a device that automatically adjusts the supply state of contained gas to control the temperature inside the furnace, thereby automating the operation of the furnace.

[Conventional technology]

Conventionally, in the above-mentioned combustion type heating furnace, the ratio between the amount of fuel supplied to the furnace heating burner and the amount of oxygen-containing gas supplied for combustion is maintained at a predetermined value, and the supply amounts are changed in synchrony. A control device was configured to control the temperature inside the furnace.
(No reference can be found.) [Problem to be solved by the invention] However, with the above-mentioned control, when the furnace temperature is controlled over a wide range, such as when firing ceramics, the burner cannot be turned off in the low temperature range. The amount of combustion gas generated in the furnace is greatly reduced, and the amount of combustion gas circulated within the furnace per unit time is greatly reduced, so the uniform heating inside the furnace in the low temperature range is greatly reduced. This caused problems such as deterioration of the quality of the object to be heated.

Furthermore, since there is inherently a limit to the range in which the burner's combustion load can be changed, when attempting to perform stable furnace temperature control over the wide range of furnace temperature control as described above, there are differences in the capabilities of each burner. Equipped with two types of burners and selectively use these burners in low temperature range and high temperature range, or equipped with a separate hot air generator that supplies hot air to the furnace and hot air supplied from that generator. Therefore, the equipment configuration, especially the control configuration, becomes significantly complicated and the equipment cost becomes high.This is especially true for equipment equipped with a hot air generator. Although uniform heating in the furnace at low temperatures can be improved to some extent, this method is particularly disadvantageous in terms of equipment cost and installation in factories, etc. since it requires the addition of separate equipment.

An object of the present invention is to rationally control the temperature inside the furnace to improve uniform heating within the furnace in a low temperature range, and to simplify the equipment configuration.

[Means for solving problems]

The characteristic configuration of the combustion type heating furnace according to the present invention is that means is provided for determining whether the furnace temperature is in a low-temperature range operating state below a first set temperature or in a high-temperature range operating state above a second set temperature. For a device that controls the furnace temperature by automatically adjusting the fuel supply state and the combustion oxygen-containing gas supply state to the furnace heating burner so that the temperature changes over time according to a setting change pattern,
Based on the determination result by the determination means, in the low temperature range operating state, the furnace temperature is controlled by changing the supply amount of oxygen-containing gas for combustion while maintaining the fuel supply amount approximately at the set minimum amount, and ,
In the high temperature range operating state, the furnace includes execution means for controlling the temperature inside the furnace by synchronizing and changing the ratio of the fuel supply amount and the combustion oxygen-containing gas supply amount while maintaining the ratio at the set value. The functions and effects are as follows.

[Effect]

In other words, in the automatic operation of a furnace that changes the temperature inside the furnace over time according to the set change pattern, the fuel supply amount and the combustion oxygen-containing gas supply amount are changed as before for high-temperature operation where there has been no particular problem in the past. The temperature inside the furnace is controlled by maintaining the ratio at the set value and changing the synchronization, but in the past there were problems in terms of uniform heating, and the addition of small capacity burners and hot air generators specifically for low temperature ranges. In low-temperature operation, where there was a problem that required combustion, the combustion oxygen-containing gas supply amount was changed while maintaining the fuel supply amount at approximately the set minimum amount. The temperature inside the furnace is controlled by changing the ratio of feed rates.

In other words, by supplying an excess amount of combustion oxygen-containing gas relative to the set minimum amount of fuel supply, the combustion calorie per unit volume of the generated combustion gas is lowered, and the temperature of the furnace atmosphere is lowered. By changing only the amount of oxygen-containing gas supplied for combustion and changing the excess rate of oxygen-containing gas for combustion, temperature control in the furnace in a low temperature range is realized.

Therefore, even in a low temperature range, a large amount of combustion gas can be generated by using excess oxygen-containing gas for combustion, and a large amount of combustion gas circulation per unit time in the furnace can be maintained, so the temperature can be lowered compared to before. It can greatly improve the uniform heating performance in the furnace in the area, and
Because of the improved uniform heating properties, the accuracy of furnace temperature control in the low temperature range can also be greatly improved.

Moreover, in the low temperature range, the fuel supply amount is maintained at almost the set minimum amount, in other words, the combustion load of the burner is maintained at the minimum load, and the width within which the burner combustion load can be changed is within the range of the furnace in the high temperature range. As long as the temperature can be controlled within a range that can be handled, there is no need to equip a small-capacity burner or hot air generator exclusively for low-temperature ranges, as in the past, in order to cope with the limits of the burner combustion load change range. The overall control configuration can be greatly simplified, and the overall equipment configuration can be made simple and compact.

〔Effect of the invention〕

As a result of the above, since the furnace has high uniform heating properties and high furnace temperature control accuracy, the finishing quality of heated products can be greatly improved, and it can also be used to expand the field of application of ceramic fired products, for example. Although it is a useful heating furnace that can contribute, it is advantageous in terms of equipment cost because of the simplified configuration, and is also advantageous in terms of installation in factories etc. due to its compact size, making it an extremely practical combustion type heating furnace.

[Example] Next, an example of the present invention will be described based on the drawings.

1 and 2 show a heating furnace for firing ceramics, in which burners 2 are arranged on each of the four side walls of the furnace 1 in two stages, upper and lower, and combustion gas is discharged from the burners 2 on each side wall. The exhaust passage 4 is connected to the furnace 1 in such a manner that a combustion gas circulation flow is formed throughout the entire area of the furnace, and an exhaust passage 4 is provided with a heat exchanger 3 for preheating combustion air.

Reference numeral 1A in the figure is a baking product mounting table which also serves as an opening/closing door of the furnace 1, and is configured so that the baking material can be taken in and out by raising and lowering the table.

As shown in FIG.
and second fuel gas supply paths 5A, 5B, and
First and second combustion air supply passages 6A and 6B branched from the combustion air main supply passage 6 are connected in parallel, respectively, and a first gas valve V ₁ for opening and closing the flow passage is connected to the first gas supply passage 5A. and a flow rate setting valve V ₂ , and a second
A second gas valve V ₃ for opening and closing the flow path is provided in the gas supply path 5B.
and a third gas valve _V4 for controlling the flow rate, and a first gas valve V4 for controlling the flow rate is installed in the first air supply path 6A.
An air valve _V5 , a second air valve _V6 for flow rate control, and the preheating heat exchanger 3 are interposed in the second air supply path 6B, respectively.

In the figure, 7 is a blower for supplying combustion air under pressure, and 8 is a device for supplying oxygen-enriched air as combustion air.

A sensor 9 for detecting the furnace temperature and a circuit 10 for setting the temporal change pattern of the furnace temperature in the firing process (see FIG. 4) are provided, and the furnace temperature t detected by the sensor 9 is set by the circuit 10. A control device 1 that automatically operates each of the gas valves and air valves to control the temperature inside the furnace so that the temperature changes over time according to a change pattern set by the control device 1.
1, and the furnace is configured to operate automatically.

In the setting change pattern shown in Fig. 4, the low temperature range A at the beginning of the furnace automatic operation is a process in which the furnace temperature t is kept below the set temperature ta to evaporate moisture and organic binder from the fired material. The high temperature region B in the middle of the operation is a step in which the furnace temperature t is made higher than the set temperature ta to sinter the fired product, and
The slow cooling zone C at the final stage of automatic furnace operation is a step in which the fired product is cooled.

To further explain the specific control configuration, the first
The flow rate setting valve V ₂ installed in the gas supply path 5A regulates the amount of fuel gas supplied only through the first gas supply path 5A to a set minimum amount such that the combustion load on the burner 2 is almost minimized. Furthermore, in conjunction with the operation of the second air valve _V6 installed in the second air supply path 6B, the third gas valve _V4 installed in the second gas supply path 5B operates in conjunction with the operation to supply the second air. The combustion air supply amount via the passage 6B and the fuel gas supply amount via the second gas supply passage 5B are synchronously changed while maintaining the set ratio. A third gas valve _V4 is linked to a second air valve _V6 .

and a circuit 11A that determines whether the operating state at each point in time is in the low temperature range A, the high temperature range B, or the slow cooling range C by comparing the elapsed time T of automatic furnace operation with the setting change pattern; Based on the determination result by the circuit 11A (see Fig. 5), (a) In the low-temperature operating state, open the first gas valve V ₁ and close the second gas valve V ₃ to supply the set minimum amount of fuel. supplying gas, and furthermore, a first air valve
While V ₅ is opened to a set opening degree and a set amount of combustion air is supplied from the first air supply path 6A, the second air valve V ₆ is automatically operated to change and adjust the overall supply amount of combustion air. (b) In the high temperature range operating state, the first gas valve V ₁
is closed and the second gas valve V ₃ is opened. Furthermore, with the first air valve VE closed, the second air valve V ₆ is automatically operated, and the third gas valve V ₄ is operated in conjunction with the fuel gas. By synchronously changing the supply amount and combustion air supply amount while maintaining their ratio at the set ratio, the furnace temperature is controlled so that it changes in accordance with the setting change pattern in high temperature range B. , (c) In the slow cooling machine C, the first and second gas valves V ₁ , V ₃ and the first and second air valves V ₅ ,
By closing V ₆ and stopping the combustion operation of burner 2, the temperature inside the furnace is lowered by natural cooling.

An execution circuit 11B is incorporated into the control device 11.

In other words, especially in the low temperature range of each firing process, control as described in (a) above is performed, and by supplying excess combustion air relative to the set minimum amount of fuel gas supply, per unit volume of generated combustion gas. The temperature in the furnace is controlled by lowering the combustion calories in the furnace to lower the temperature of the atmosphere in the furnace, and in that state, changing only the supply amount of combustion air and changing the excess rate of combustion air. As a result, the circulation amount of combustion gas in the furnace is increased to improve uniform heating in the furnace in the low temperature region A, and
Even if the furnace temperature control range is wider than the range in which the combustion load of the burner 2 can be changed, the entire control range from the low temperature range A to the high temperature range B can be handled with just one type of burner 2.

[Another example]

Next, another embodiment of the present invention will be proposed.

A low temperature range in which the furnace temperature is controlled by changing the supply amount of combustion oxygen-containing gas (for example, air) while maintaining the fuel supply amount at approximately the set minimum amount, and the fuel supply amount and combustion oxygen-containing gas supply amount. and to set each of the high-temperature ranges in which the temperature inside the furnace is controlled by changing the synchronization while maintaining their ratio at the set ratio, the control range where the temperature inside the furnace is equal to or lower than the first set temperature is set as the low-temperature range, and The control range in which the furnace temperature is equal to or higher than the second set temperature may be defined as the high temperature range, and the first and second set temperatures may be different. It is also possible to set a heating control range.

The change pattern of the temperature inside the furnace may be set as appropriate depending on the use of the furnace.

In order to determine whether the operating state is a low-temperature region operating state or a high-temperature region operating state, the furnace temperature information given from the furnace temperature detection means 9 is used instead of comparing the automatic operation with the elapsed time against the setting change pattern. The discrimination may be made based on the discrimination means 1.
Various changes can be made to the specific determination method and configuration of 1A.

The specific configuration of the execution means 11B installed in the control device 11 so as to control the furnace temperature in different control modes in the low temperature range and the high temperature range as described above is, for example, a configuration using a microcomputer or a configuration consisting of a sequence circuit. etc., various species changes are possible.

The configuration for changing the amount of fuel supply and the configuration for changing the amount of oxygen-containing gas for combustion include a fuel supply path 5 and a combustion oxygen-containing gas supply path 6 for the burner 2.
A quantity control valve is installed in each of the valves, and by simply operating these valves automatically, low temperature range furnace temperature control and high temperature range furnace temperature control, which have different control forms, can be performed. Various improvements can be made to the specific flow path configuration and valve configuration for changing the amount of fuel supplied and the amount of oxygen-containing gas supplied for combustion.

The use of the combustion type heating furnace according to the present invention is not limited.

[Brief explanation of the drawing]

1 to 5 show embodiments of the present invention,
Figure 1 is a longitudinal sectional view, Figure 2 is a planar sectional view, and Figure 3 is a longitudinal sectional view.
The figure is a system diagram showing the control configuration, FIG. 4 is a graph showing the change pattern of the furnace temperature, and FIG. 5 is a table showing the valve operation pattern. 2...Burner, 9...Furnace temperature detection means, 10
... Furnace temperature change pattern setting means, 11 ... Control device, 11A ... Discrimination means, 11B ... Execution means.

Claims (1)

[Claims] 1. Means 10 for setting a temporal change pattern of the furnace temperature and means 9 for detecting the furnace temperature are provided, and the furnace temperature detected by the detecting means 9 follows the change pattern set by the setting means 10. The combustion type heating furnace is equipped with a device 11 that automatically adjusts the fuel supply state and the combustion oxygen-containing gas supply state to the furnace heating burner 2 so that the temperature inside the furnace changes over time. A means 11A is provided for determining whether the temperature is in a low-temperature range operating state where the temperature is below the first set temperature or a high-temperature range operating state where the temperature is higher than or equal to the second set temperature. The furnace temperature is controlled by changing the supply amount of oxygen-containing gas for combustion while maintaining the fuel supply amount at approximately the set minimum amount, and in the high temperature range operation state, the fuel supply amount and the combustion oxygen Execution means 11B that controls the furnace temperature by synchronizing and changing the supply amount while maintaining the ratio to the supply amount of the contained gas at the set value.
A combustion type heating furnace comprising the control device 11.