JPH08246058A - Automatic combustion control method in continuous type heating furnace - Google Patents

Abstract

PURPOSE: To prevent deficiency in heating by measuring the temperature of a steel sheet at the intermediate position of a heating band, comparing the actual and planned heat patterns and raising the furnace temperature on a heating band at a temperature measuring position or a next heating band with the temperature difference. CONSTITUTION: A steel material is heated in a continuous type heating furnace capable of controlling the furnace temperature independently at each heating zone. The slub temperature t2 is measured at a point A on three bands-inlet side at the intermediate position of the heating furnace. The temperature difference t=t1-t2 between the planned slub temperature t1 and t2 is obtained. When the temperature difference (t) is equal to or higher than a prescribed value, a correcting operation is executed. The temperature rising rate is obtained from the actual slub temperature t2 and the planned slub temperature t3 at a point B on three bands-outlet side. A set temperature, at which the temperature rising rate is ensured, is calculated and is corrected as a set temperature of the furnace band. The actual temperature of the steel material is made accurately close to a target temperature, thereby improving productivity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic combustion control method in a continuous heating furnace in which each heating zone can be independently temperature controlled.

[0002]

2. Description of the Related Art Generally, a continuous steel material heating furnace is capable of heating a steel material to a predetermined rolling temperature and supplying it to a subsequent rolling line. When the temperature of the steel material heated in such a continuous steel material heating furnace does not reach the predetermined rolling temperature, it has a great influence on rolling, resulting in a large loss in rolling operation and quality, and the steel material temperature is higher than necessary. When it becomes higher, the heat loss in the continuous steel heating furnace increases, so in such a continuous steel heating furnace, it is important how to heat the steel to a predetermined rolling temperature with a minimum amount of fuel. It is an issue. Therefore, it is necessary to uniformly heat the steel material to a temperature suitable for rolling and to supply the heated steel material corresponding to the rolling pitch required by the rolling mill. Therefore, for example, Japanese Patent Publication No. 4-69209 is known as a temperature control method for a continuous heating furnace in which slabs, which are different types of materials to be heated, are simultaneously and continuously heated.

In this patent publication, the remaining residence time of each steel material in the heating furnace is calculated for the steel materials existing in the heating furnace from the operating state of the walking beam, and the upper atmosphere temperature in the furnace above the heating furnace and the furnace temperature below The inner and lower atmosphere temperature and the temperature of the cooling water in the skid cooling pipe are measured, and the thickness of each of the above steel materials is measured for each of a plurality of parts including a skid contact part of the material to be heated in the furnace by using the measured temperatures. The temperature of the material to be heated at the current time is calculated by the heat transfer model for each position in the direction, and then either the upper atmosphere temperature in the furnace or the lower atmosphere temperature in the furnace after the current time, or both set temperatures are changed. At the time when the material to be heated passes through the band, the temperature at all or at specific positions is predicted and calculated, and the difference between the predicted temperature and the target temperature is within a certain value. In the method of obtaining the air temperature and the lower atmosphere temperature in the furnace and setting the temperature as the set furnace temperature for the steel material, each steel material is calculated by calculating the set furnace temperature for all the steel materials in the heating furnace. Extraction order, distance to the strip outlet of the steel material, absolute value difference between the steel material setting furnace temperature and the current furnace temperature, and if different steel grade steel materials are mixed in the heating furnace, the weight of the steel material is calculated and this weight is used. A temperature control method for a continuous heating furnace has been proposed in which the temperature inside the heating furnace is controlled for all the steel material setting furnace temperatures.

[0004]

However, in the conventional method described in Japanese Patent Publication No. 4-69209, the heat pattern obtained by weighting and averaging the heat pattern of each steel material is obtained, and the furnace temperature is controlled according to the pattern. . Therefore, when looking at individual steel products, there are cases where the steel products are below the planned heat pattern for each steel product, which causes insufficient heating, which is a serious problem in terms of quality or operation. The present invention has been made to solve the above problems, and when heating a material to be heated, for steel materials that do not reach the target temperature, the temperature difference is compared with the furnace temperature of the heating zone at the comparison position or the furnace temperature of the next heating zone. It is an object of the present invention to provide a continuous heating furnace control method capable of accurately heating a material to be heated to each target temperature by raising the temperature.

[0005]

In order to achieve the above object, the gist of the invention is to provide a heating zone intermediate position in a continuous heating furnace in which the heating temperature of each heating zone can be controlled independently. The steel material temperature is measured with, and the actual and expected heat patterns of the heat pattern obtained by the measured values are compared.If the actual result is lower than the planned value, the temperature difference is compared with the heating zone at the comparison position or the next heating zone. An automatic combustion control method in a continuous heating furnace is characterized in that a predetermined heat pattern is corrected by raising the furnace temperature.

[0006]

The present invention will be described in detail below with reference to the drawings. The steel material rolled by the hot rolling mill needs to be heated to a predetermined temperature before rolling, so it is usually continuous in a multi-zone continuous heating furnace with easy material insertion and extraction and high production efficiency. It is heated. In recent years, the types, sizes, and heating targets of continuously heated steel products are often different as the number of rolled products decreases, and from the viewpoint of improving product quality and energy saving, the heating target temperature It is necessary to prevent insufficient heating and overheating, especially insufficient heating.
Therefore, in the present invention, when heating each of the steel materials in a multi-zone continuous heating furnace, the heating conditions for all steel materials within the heating control range of each zone (target heating temperature, skid mark, soaking degree, etc.) Further, it is necessary to calculate the furnace temperature required for each steel material from the preheated residence time and determine the heating pattern for each steel material.

FIG. 1 is a diagram showing a heat pattern setting method according to the present invention. As shown in FIG. 1, the calculation procedure is set according to the following procedure. First, the steel material temperature is measured on the side of the zone 3 at the point A, which is the intermediate position of the heating furnace, and the planned steel material temperature t ₁
And a temperature difference t between the actual steel material temperature t ₂ and the actual steel material temperature t ₂ . When this temperature difference t is equal to or more than a certain value, the following temperature difference restoration processing is performed. That is, the actual steel material temperature t ₂ and the next zone in-reactor time S
The temperature increase rate v is calculated from The furnace temperature T ₂ that can ensure the calculated heating rate v is corrected as the next zone set furnace temperature. After the set furnace temperature is corrected, the steel material thermometer etc. is recalculated to control combustion.

[0008]

EXAMPLE A slab is transferred by a walking beam and baked in a heating furnace. The heating furnace is divided into a plurality of zones in the furnace length direction and temperature control is performed. That is, the slab heating conditions in the heating furnace are calculated according to the required furnace temperature of each zone by calculating the required furnace temperature of each zone, comparing the appropriate heat pattern of each slab with the appropriate heat pattern of the front slab of each slab. Things
In the present invention, particularly in the heat pattern as shown in FIG. 1, when the slab temperature t ₂ is measured at the point 3 on the zone entrance side A corresponding to the intermediate position of the heating furnace, and the value of 800 to 900 ° C. is obtained, the heating furnace is When the planned slab temperature t ₁ calculated by the slab temperature calculation at the time of charging is set to 900 to 1000 ° C., the temperature difference t from the measured value is calculated to be 50 to 100 ° C. The correction calculation according to the present invention is performed only when the temperature difference t is 50 ° C. or more. That is, the actual slab temperatures t ₂ and 3
The planned slab temperature t ₃ of the zone 3 on the zone B on the zone side is 100.
When set to 0 to 1100 ° C, the in-reactor time S for 3 zones is 20
Since it is 30 minutes, heating rate v = (t ₃ -t ₂₎
/ S gives v of 3 to 10 ° C./min. On the other hand, the set furnace temperature T ₂ capable of ensuring the temperature rising rate v is calculated, and as a result, 1100 to 1200 ° C. is corrected as the furnace zone set furnace temperature. After the correction of the set furnace temperature, the slab temperature calculation is recalculated and combustion control is performed. By performing such combustion control, it becomes possible to correct the set furnace temperature of each zone of the heating furnace that can bring the actual temperature of the extracted steel material closer to the target temperature with higher accuracy than in the conventional technology, thus improving productivity. Could be achieved.

[0009]

As described above, according to the present invention, in the continuous heating furnace capable of independently controlling the furnace temperature of each heating zone,
Insufficient heating, major problems in quality or operation are resolved,
The steel material can be continuously heated. This makes it possible to correct the set furnace temperature of each zone of the heating furnace for a steel material which does not reach the target temperature, and has an excellent effect of improving productivity.

[Brief description of drawings]

FIG. 1 is a diagram showing a heat pattern setting method according to the present invention.

Claims (1)

[Claims] 1. A continuous heating furnace in which each heating zone can be independently controlled in temperature, the steel material temperature is measured at an intermediate position of the heating zone, and the actual heat pattern obtained by the measured value is compared with the expected heat pattern. When the actual performance is below the schedule, the temperature difference is corrected to the scheduled heat pattern by raising the furnace temperature of the heating zone at the comparison position or the next heating zone. Combustion control method.