JPH07280258A - Combustion controlling method for burner of industrial kiln - Google Patents

Abstract

PURPOSE:To make a temperature in a kiln uniform by equalizing a delay time to a burning time when the delay time calculated from a necessary heat quantity is longer than the burning time, maximizing an air injection amount in the case of burning of each burner and setting a fuel injection amount to a necessary combustion amount. CONSTITUTION:When an ignition delay time Td calculated from a necessary heat quantity is shorter than a burning time Ts, combustions of burners A, B, C, D are set to constant air fuel ratio combustion in the case of maximum air injection amount and fuel injection amount. When the delay time Td calculated from necessary heat quantity is longer than the time Ts, the time Td is set equally to the time Ts. The combustions of the burners A, B, C, D are set to maximum air injection amount and necessary fuel injection amount. Accordingly, since there are not OFF times of the burners A, B, C, D substantially in an entire range of necessary input heat quantity of 0-100% to an industrial kiln, gas in the kiln is always circulated. Thus, a temperature in the kiln can be made uniform.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a burner combustion control method in an industrial kiln (including a heat treatment furnace for metal materials).

[0002]

2. Description of the Related Art In recent years, heating technology for improving temperature distribution in a furnace has been advanced from the viewpoint of diversification of heat treatment technology and improvement of quality of material to be heated. In the case of a batch-type heat treatment furnace, the amount of heat required for soaking is 1/10 to that for maximum heating.
Only 1/20 heat is required. In order to ensure the uniformity of the temperature in the furnace during such low combustion, Japanese Patent Laid-Open No. 60-
The heating method of Japanese Patent No. 144516 is disclosed. In this heating method, the combustion of each burner is a constant air-fuel ratio combustion at the maximum air ejection amount and the fuel ejection amount, and a plurality of burners are ignited sequentially in sequence to efficiently heat the iron or steel heat treatment furnace. At the same time, it is a method of heating the furnace to make the temperature inside the furnace uniform.

[0003]

However, even in the above heating method, when the required amount of heat is small, there occurs a time during which all the burners are turned off, during which the gas in the furnace is not circulated and the furnace pressure is reduced. However, there is a problem that it becomes difficult to maintain the temperature of the furnace, and the air outside the furnace enters the furnace, making it difficult to make the temperature inside the furnace uniform. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a burner combustion control method in an industrial kiln in which the temperature inside the furnace can be made uniform even when the heating amount is small.

[0004]

A method according to the above-mentioned object.
The burner combustion control method in the industrial kiln described above is a combustion control method for each burner of the industrial kiln having a plurality of burners with a combustion time Ts that sequentially ignites with a delay time Td, wherein When the delay time Td is shorter than the combustion time Ts, the combustion of each burner is a constant air-fuel ratio combustion at the maximum air ejection amount and the fuel ejection amount, and the delay time Td calculated from the required heat amount is
When it is longer than the combustion time Ts, the delay time Td
And the combustion time Ts are made equal to each other, and the combustion of each burner is controlled so that the air ejection amount is the maximum and the fuel ejection amount is the required combustion amount. It should be noted that the maximum air ejection amount and fuel ejection amount of the burner do not mean only the air ejection amount and the fuel ejection amount at which the burner exerts the maximum capacity,
This includes cases where the burner is used with a capacity slightly lower than the maximum output value for reasons such as extending the life of the burner. Further, the burner in the present invention includes not only a normal burner that ejects air and fuel but also a regenerative burner that repeats combustion and exhaust.

[0005]

In the burner combustion control method for an industrial kiln according to claim 1, when the ignition delay time Td of each burner calculated from the required heat amount is shorter than the combustion time Ts of each burner, combustion of each burner is performed. Is the constant air-fuel ratio combustion at the maximum air ejection amount and fuel ejection amount.
Either burner always burns, and combustion exhaust gas can be fed into the furnace. Also, the ignition delay time Td of each burner calculated from the required heat is the combustion time Ts of each burner.
When it is longer, the delay time Td is made equal to the combustion time Ts. As a result, one of the burners is always burning, and as a result, the combustion exhaust gas can be supplied into the furnace. As a result, the circulation of the gas in the furnace can be ensured and the furnace pressure can be ensured, so that it is possible to prevent air from entering from the outside.

[0006]

Embodiments of the present invention will now be described with reference to the accompanying drawings to provide an understanding of the present invention. 1 is an explanatory view of a burner combustion control method according to an embodiment of the present invention, FIG. 2 is a plan view of an industrial kiln, and FIG.
FIG. 4 is an explanatory diagram of a combustion state of a burner according to an embodiment of the present invention.

As shown in FIG. 2, the burner control method according to one embodiment of the present invention is applied to an industrial kiln 10 provided with four burners A, B, C, and D for combustion. Examples will be described. First, as shown in FIG. 3, the required amount of heat input to the industrial kiln 10 is the entire burner A.
In the case of 25% or more (1 / the number of burners) of the maximum amount of heat when burning ~ D, the burners A to D burn with the maximum air ejection amount and the maximum fuel ejection amount. In this case, as shown in FIG. 1A, the ignition delay time of each burner A to D is Td, the combustion time of each burner A to D is Ts,
Assuming that the extinction time of each burner A to D is Ti (a function of Td and Ts), the total calorific value Q of each burner is 4
q × Ts / (Ts + Ti) (however, q is the maximum calorific value of each burner), so Ti (= 4T
By controlling d-Ts, the amount of fuel supplied can be adjusted and the amount of heat input can be controlled.

Next, the required amount of heat input to the industrial kiln 10 is 25% (1) of the maximum amount of heat when the burners A to D are burned.
1 / B), the ignition delay time Td of each of the burners A to D and the combustion time Ts of each of the burners A to D are set to be the same, as shown in FIG. Ignite D. The amount of air supplied to each of the burners A to D is constant, but the amount of fuel supplied decreases in accordance with the amount of heat required.

As a result, one of the burners A to D must always be burning in the industrial kiln 10, combustion exhaust gas is generated, the furnace gas is circulated, and the furnace temperature is made uniform. In addition, the local decrease in the furnace temperature due to the intrusion of air from the outside due to the decrease in the furnace pressure is eliminated. In addition,
One of the burners A to D is ignited,
The other three burners are supposed to be extinguished, and it is preferable to stop the combustion air for the extinguishing burners in order to prevent a local decrease in the furnace temperature, but the combustion air was preheated. If it is air, only air may be supplied to the burner.

Although the above embodiment has been described with respect to the case where four burners A to D are used, the present invention is naturally applied to an industrial kiln having a smaller number and a larger number of burners, and each burner is independent. The present invention is also applicable to the case where the burners are separately controlled to a plurality of groups, in addition to the case where the control is performed to. Further, the industrial kiln can be applied to both a batch type industrial kiln and a continuous type industrial kiln.

[0011]

As is apparent from the above description, the burner combustion control method in the industrial kiln according to claim 1 is as follows.
Since there is no time for the burner to be turned off in the substantially entire range where the required heat input to the industrial kiln is 0 to 100%, the furnace gas is constantly circulated and the furnace temperature can be made uniform. Further, since the furnace pressure can be normally maintained, it is possible to prevent local decrease in the furnace temperature by preventing air from entering the furnace from the outside.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a burner combustion control method according to an embodiment of the present invention.

FIG. 2 is a plan view of an industrial kiln.

FIG. 3 is an explanatory diagram of a combustion state of a burner according to an embodiment of the present invention.

[Explanation of symbols]

 10 Industrial kiln A burner B burner C burner D burner

Claims (1)

[Claims] 1. A combustion time T in which ignition is sequentially performed with a delay time Td.
A method of controlling combustion of each burner of an industrial kiln having a plurality of burners of s, wherein when the delay time Td calculated from the required heat amount is shorter than the combustion time Ts, the combustion of each burner is maximum. When the delay time Td calculated from the required heat amount is longer than the combustion time Ts, the delay time Td and the combustion time Ts are equalized, The burner combustion control method in an industrial kiln is characterized in that the combustion amount of each burner is the maximum air ejection amount and the fuel ejection amount is the required combustion amount.