JPH08143948A - Oxygen burner combustion method in heating furnace - Google Patents

Abstract

PURPOSE: To restrain the highest furnace temp. and to secure the uniform furnace temp. distribution by alternately and intermittently generating the longest flame in the width direction of a heating furnace in order to uniformly heat a material to be heated. CONSTITUTION: In an oxygen burner combustion method of the heating furnace for heating the material to be heated with plural oxygen burners 3a, 3b, the whole oxygen burners 3a, 3b in a zone 1 are burnt at the rated combustion quantity until the actual measured furnace temp. in zone 1 of the heating furnace reaches the setting furnace temp. After the actual measured furnace temp. in the zone 1 reaches the setting furnace temp., the oxygen burners 3a, 3b mutually faced in the width direction of the furnace in the zone 1 are alternately and intermittently changed over in the condition near the rated combustion quantity to execute the combustion of the oxygen burners in the heating furnace.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for burning an oxygen burner in a heating furnace for heating a material to be heated such as a slab, billet or strip to a predetermined target temperature with an oxygen burner.

[0002]

2. Description of the Related Art Conventionally, in this type of heating furnace, an air burner has been generally used to burn a fuel with air to heat a material to be heated. Recently, however, the fuel has been changed to oxygen or oxygen-enriched air. Oxygen burners that burn and heat the material to be heated are drawing attention. Compared with the conventional air burner, this oxygen burner has a combustion gas amount of about 1/4 and a high carbon dioxide (CO ₂ ) and water vapor (H ₂ O) concentration. Also, in addition to the low fuel consumption rate due to the heat transfer promotion effect due to the increase in radiant heat transfer in the furnace, it also has the advantage that carbon dioxide, a global warming substance, can be easily recovered.

On the other hand, the oxygen burner is different from the air burner in that
Since the flame temperature is high and the amount of combustion gas is small, there is a problem that the temperature distribution in the furnace becomes non-uniform, and the material to be heated cannot be heated uniformly. This tendency is particularly remarkable in the low burn rate region of the oxygen burner. . On the other hand, there is an operating method of a heating furnace having a side burner, that is, a combustion method, as disclosed in, for example, JP-A-60-50113.

The feature of this technique is to uniformly heat the material to be heated while controlling the temperature in the width direction of the furnace by controlling so that the flame length of the burner does not change even if the burning rate of the burner changes. Figure 5 to aim and achieve this
In the high burn rate region, the burner flame length is controlled by using a two-fuel variable burner length variable burner as shown in Fig. 4, and it becomes impossible to control the burner flame length. In the low burning rate region, the specified burner is thinned out,
The technical means is to control the flame length by increasing the burning rate of other burners.

[0005]

However, the above-mentioned method is premised on the use of a two-fuel variable-length variable-length burner, but the oxygen burner has a higher combustion speed and a smaller amount of combustion gas than an air burner. With a burner, the flame becomes an extremely high-temperature short flame, making it difficult to construct a variable-flame length burner such as an air burner with an oxygen burner itself, and burners other than the thinning burner burn continuously. Therefore, the material to be heated is locally overheated by the high temperature flame of oxygen combustion,
There was a problem of melting and melting. The present invention was devised to solve the above problems, and its purpose is to uniformly heat the material to be heated, by alternately generating the longest flame in the furnace width direction of the heating furnace, An object of the present invention is to provide an oxygen burner combustion method for a heating furnace that suppresses temperature and ensures a uniform furnace temperature distribution.

[0006]

SUMMARY OF THE INVENTION The present invention has the following structure. (1) In the oxygen burner combustion method of a heating furnace in which a material to be heated is heated by a plurality of oxygen burners, all oxygen burners in the zone are rated until the actually measured furnace temperature in the heating furnace zone reaches the set furnace temperature. After burning with the combustion amount and the measured furnace temperature in the zone reached the set furnace temperature, the opposing oxygen burners in the furnace width direction in the zone were switched alternately intermittently in a state close to the rated combustion amount. To burn.

(2) In the alternate intermittent switching combustion method of the oxygen burner, the time zone in which the measured furnace temperature is equal to or higher than the set furnace temperature is set as the combustion interruption time of all oxygen burners, and the time zone in which the measured furnace temperature is lower than the set furnace temperature. Be the combustion time of either one of the oxygen burners provided facing each other. (3) In the alternate intermittent switching combustion method of the oxygen burner, the mode of the alternate intermittent switching combustion of adjacent oxygen burners in the furnace length direction in the zone is set to the reverse mode.

[0008]

In the method for burning an oxygen burner in a heating furnace according to the present invention, the burning oxygen burner is always burned at or near the rated burning amount, so that the longest flame having straightness in the furnace width direction is formed. Thus, the furnace temperature distribution in the furnace width direction becomes uniform. In addition, after the measured furnace temperature reaches the set furnace temperature, the oxygen burners facing each other in the furnace width direction of the heating furnace are intermittently switched and burned in a state close to the rated combustion amount. Flames are alternately formed in the furnace width direction of the heating furnace, and the furnace temperature distribution becomes uniform, and the measured furnace temperature is controlled to the set furnace temperature by intermittent combustion, so the high temperature flame of oxyfuel combustion is suppressed, Melting damage due to overheating of the material to be heated can be prevented.

[0009]

EXAMPLE FIG. 1 is a plan view of one zone of a side burner type heating furnace for explaining an oxygen burner combustion method for a heating furnace of the present invention, and FIG. 2 is an AA of the side burner type heating furnace of FIG. It is a longitudinal cross-sectional view in a plane. As shown in FIGS. 1 and 2, the outer shell of the zone 1 of the side burner type heating furnace is provided with furnace walls 2a, 2 of refractory.
b, 2c, and an oxygen burner 3a, on the side walls 2a, 2b on both sides in the furnace length direction of the zone 1 of this heating furnace.
A plurality of pairs of 3b are arranged so as to face each other, and fuel and oxygen are supplied to the oxygen burners 3a and 3b through pipes not shown in the figure to oxy-combust the fuel.
The material 5 to be heated is heated with a and 4b.

Usually, the heating furnace is a zone 1 as shown in FIG.
Are connected in the furnace length direction of the heating furnace,
The material to be heated 5 is loaded into the heating furnace through a charging door on one end side in the furnace length direction of the heating furnace, and the pusher, walking hearth,
While being moved in the zone of the heating furnace by a carrying device such as a walking beam, it is heated to a predetermined temperature and extracted from the extraction door on the other end side.

FIG. 3 is a conceptual diagram showing the heating time, the measured furnace temperature, the set furnace temperature, the temperature of the material to be heated, and the combustion state of the oxygen burners 3a, 3b in the oxygen burner combustion method for the heating furnace according to the present invention. In FIG. 3, the time zone θab until the actually measured furnace temperature reaches the set furnace temperature of 1200 ° C. is that the oxygen burners 3a and 3b in the zone 1 of the heating furnace are simultaneously burned at the rated combustion amount to obtain the zone 1 of the heating furnace. The longest flames 4a and 4b of high temperature having straightness in the furnace width direction are simultaneously generated.
The low-temperature material 5 is rapidly heated by a and 4b.

On the other hand, after the measured furnace temperature reaches the set furnace temperature of 1200 ° C., a plurality of pairs of oxygen burners 3a and 3b facing each other in the zone 1 of the heating furnace are alternately turned on and off in a state close to the rated combustion amount. Then, switching combustion is performed, and the longest flames 4a and 4b of high temperature having straightness are alternately intermittently generated in the furnace width direction of the zone 1 of the heating furnace.

That is, in the time zones θ1, θ2, ... Where the measured furnace temperature is 1200 ° C. or higher, the oxygen burners 3a, 3b are used.
The combustion is controlled so that the measured furnace temperature becomes the set furnace temperature, and local overheating of the heated material 5 due to the high temperature flames 4a, 4b, that is, melting loss is prevented. Further, in the time zones θa1, θb1, ... where the measured furnace temperature is equal to or lower than the set furnace temperature 1200 ° C,
The oxygen burners 3a and 3b are alternately switched and burned in a state close to the rated combustion amount, and the longest flames 4a and 4b of high temperature are alternately generated intermittently in the furnace width direction of the zone 1 of the heating furnace, and the furnace temperature distribution is The material to be heated 5 is homogenized and uniformly heated. In addition,
The measured furnace temperature referred to here is the average furnace temperature or the representative furnace temperature in the zone 1 of the heating furnace measured by a thermometer such as a thermocouple, and the set furnace temperature is used for instrumentation control for combustion control. It is the control furnace temperature.

Next, the effect of the present invention is obtained by using a combustion experimental furnace having an inner diameter of 0.9 m and a length of 4.0 m in a combustion amount of 250,000 Kcal / h.
The coke oven gas (true calorific value 4200 Kcal / Nm ³ ) burning oxygen (oxygen concentration 99.9% or more) was installed and confirmed. As a result, in the conventional combustion control method using only the burner burning rate, The temperature control range of the actually measured furnace temperature was ± (20 to 40) ° C. with respect to the set furnace temperature, whereas the temperature control range of the oxygen burner combustion method of the present invention was ± (10 to 40) ° C.
20) It was possible to reduce the temperature to half. Further, the maximum furnace temperature difference in the burner shaft length direction (= maximum furnace temperature-minimum furnace temperature) is about 90 ° C. in the conventional method of controlling combustion only by the burner burning rate, and 50 ° C. or less in the oxygen burner burning method of the present invention. Could be reduced to

FIG. 4 shows another embodiment of the method for burning an oxygen burner in a heating furnace according to the present invention, which is an alternating intermittent switching combustion mode of adjacent oxygen burners in the furnace length direction of zone 1 of a side burner type heating furnace. The oxygen burners 3a and 3b are alternately arranged in the furnace length direction so that
A more uniform furnace temperature distribution can be obtained for the above embodiment.

The present invention is not limited to the above-mentioned embodiment. For example, (1) the oxygen burner is an oxygen-enriched air burner, (2) an axial flow type continuous heating furnace and batch type heating. It is of course possible to apply it to a combustion method of an adjacent oxygen burner such as a furnace, and of course various modifications can be made without departing from the gist of the present invention.

[0017]

EFFECTS OF THE INVENTION According to the method for burning an oxygen burner in a heating furnace of the present invention, (1) the oxygen burner is burned at a rated combustion amount or in a state close to the rated combustion amount to form a longest flame having straight running. , After the measured furnace temperature reaches the set furnace temperature, the opposing oxygen burners in the furnace length direction of the heating furnace are alternately intermittently switched and burned, so that the high temperature flame of oxyfuel combustion moves in the furnace width direction of the heating furnace. The non-stationary structure makes the furnace temperature distribution uniform, and as a result, the material to be heated can be uniformly heated. (2) Further, in the alternate intermittent switching combustion of the oxygen burner, the time when the measured furnace temperature is equal to or higher than the set furnace temperature is set as the combustion interruption time of the oxygen burner. By controlling the set furnace temperature, it is possible to obtain an excellent effect such that melting loss due to overheating of the material to be heated can be prevented.

[Brief description of drawings]

FIG. 1 is a plan view of a side burner type heating furnace for explaining an oxygen burner combustion method for a heating furnace of the present invention.

FIG. 2 is a vertical cross-sectional view taken along the line AA of the side burner type heating furnace of FIG.

FIG. 3 is a conceptual diagram showing an embodiment of an oxygen burner combustion method for a heating furnace according to the present invention.

FIG. 4 is a plan view of a side burner type heating furnace showing another embodiment of the oxygen burner combustion method for the heating furnace of the present invention.

FIG. 5 is a conceptual diagram of a gas two-flow type variable flame length type air burner.

[Explanation of symbols]

1 Zone 2a, 2b, 2c Furnace wall 3a, 3b Oxygen burner 4a, 4b Flame 5 Heated material 6 Fuel nozzle for long flame 7 Fuel nozzle for short flame 8 Combustion air flow passage 9 Long flame outlet 10 Short flame outlet 11 Swirling blade θab Time zone until the measured furnace temperature reaches the set furnace temperature θ1, θ2, ... Time zone when the measured furnace temperature is equal to or higher than the set furnace temperature θa1, θa2, ... Oxygen burner when the measured furnace temperature is equal to or lower than the set furnace temperature Combustion time zone of 3a θb1, θb2, ... Combustion time zone of oxygen burner 3b when the measured furnace temperature is below the set furnace temperature

Claims (3)

[Claims] 1. An oxygen burner combustion method for a heating furnace in which a material to be heated is heated by a plurality of oxygen burners, the total oxygen burner in the zone until the actually measured furnace temperature in the zone of the heating furnace reaches a set furnace temperature. After the measured furnace temperature in the zone reaches the set furnace temperature, the opposite oxygen burners in the furnace width direction in the zone are alternately turned on and off in a state close to the rated combustion amount. A method for burning an oxygen burner in a heating furnace, which is characterized by carrying out switching combustion. 2. In the combustion method of alternately switching the oxygen burner, the time zone in which the measured furnace temperature is equal to or higher than the set furnace temperature is set as the combustion interruption time of all oxygen burners, and the time zone in which the measured furnace temperature is lower than the set furnace temperature is set. 2. The combustion time of one of the oxygen burners provided facing each other is set.
A method for burning an oxygen burner in a heating furnace as described. 3. The alternating intermittent switching combustion method for oxygen burners, wherein the mode of the alternating intermittent switching combustion of adjacent oxygen burners in the furnace length direction in the zone is a reverse mode. A method for burning an oxygen burner in a heating furnace as described.