JPH0532447B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a method of controlling a continuous heating furnace.

[Conventional technology]

Conventionally, computer control of the baking temperature of a steel billet in a heating furnace has been carried out by controlling the temperature of the steel billet at each position in the furnace from charging to extraction, as shown in, for example, Japanese Patent Application Laid-open No. 75527/1983. is determined by heat transfer calculation based on the temperature distribution in the furnace, the size of the steel billet, physical property values, and actual furnace time, and a method is adopted in which the temperature in the furnace is set to follow a certain temperature increase pattern. ing.

[Problem that the invention seeks to solve]

In the conventional continuous heating furnace control method described above, the steel billet charged into the heating furnace is controlled by a combination of size, physical properties, and type of steel to be heated (upper/lower limits of extraction temperature of the steel billet, limits on soaking degree). However, due to high-mix, low-volume production, there may be several dozen types of billet groups in the furnace, and even if a preferable temperature increase pattern for each billet could be determined from the perspective of energy saving, etc. However, it was difficult to bake each piece of steel exactly as specified.

This invention was made to solve this problem, and the purpose of this invention is to set the furnace temperature at which various steel pieces in the furnace can be fired on average or preferentially according to each temperature increase pattern. The purpose of this invention is to obtain a control method for a continuous heating furnace that can determine set values.

[Means for solving problems]

The method for controlling a continuous heating furnace according to the present invention is to set the furnace temperature of each steel billet in order to bake various steel billets in the furnace averagely or preferentially to a certain steel billet in accordance with each temperature increase pattern. The value is multiplied by a weighting coefficient for furnace temperature setting, and the weighted average value is set as the set furnace temperature.

[Effect]

In this invention, the furnace temperature set value of each slab is multiplied by the furnace temperature setting weighting coefficient and the weighted average value is set as the set furnace temperature. It becomes possible to bake evenly or preferentially a certain piece of steel using a temperature increase pattern.

〔Example〕

The control method of the present invention will be explained below. As shown in Figure 1, the heating furnace is divided into j parts in the furnace length direction, and based on the actual fuel flow rate, a heat balance formula that takes into account heat generation, radiation, convection, and heat transfer is created, and an unsteady nonlinear The simultaneous equations are convergently calculated using Newton's method, and the furnace temperature distribution is determined.

Based on this temperature, a known heat transfer difference equation is solved for all the steel materials present in the furnace to determine the temperature of the steel billet. Once the target temperature is determined based on the temperature increase pattern determined from the viewpoint of energy saving, etc., the furnace temperature setting value at a certain position for each billet is determined from the above-mentioned current billet temperature, target temperature, etc. could be done. In this way, the required furnace temperature setting value for each billet at a certain position was determined, but in general, in a heating furnace, the fuel flow control device is only attached to each control zone, and the required furnace temperature setting value for each billet is determined. The set temperature is just a set value for each zone into which each control band is divided. So, do the following,
It is necessary to convert this set value to the set value of the zone where the control thermometer is located.

T _gA ′=T _gA + (T _g (j)−T _g (k)) …(1) However, T _gA ′: Converted set furnace temperature T _g (j): Inside of the furnace in the furnace temperature setting zone Temperature T _g (k): Furnace temperature in the zone where the control thermometer is located in the control zone including the furnace temperature setting zone In the above equation (1), the values in parentheses indicate the furnace temperature distribution determined above. Therefore, it corresponds to the correction term for the set value, and by doing so, the necessary furnace temperature for a certain slab can be reliably obtained. The furnace temperature setting value for each steel billet was determined by the method described above, and based on this setting value, the setting value for each control band was determined by the following formula.

T _gk = Σc(i)T _gA ′(i)/Σc(i) …(2) Here, c(i) is the weighting coefficient for baking for each steel slab, and if c(i) is the same for all If you do so, each billet will be baked to the target temperature on average, and if you want to bake a certain billet preferentially during operation, you can achieve this by increasing the weight of c(i) for that billet. It becomes possible. FIG. 2 shows this state.

Next, heating furnace control based on an embodiment of the present invention will be explained with reference to FIG.

In FIG. 3, 101 is a heating furnace, 102 is an operation information management section, 103 is a fuel flow control section, and 104
1 is a furnace temperature measuring part such as a thermocouple, 105 is a burner, 1
06 is a furnace temperature setting function section. Furnace temperature setting function section 1
06 is roughly divided into four functions: current temperature calculation 1, future temperature calculation 2, temperature increase pattern calculation 3, and furnace temperature setting calculation 4. Logics 1 and 2 have almost the same logic, and have functions for calculating furnace temperature, billet temperature, and billet movement. First, the current furnace temperature and billet temperature are calculated by the current temperature calculation 1 in the furnace temperature setting function section 106 by inputting the billet information and actual fuel flow rate from the operation information management section 102 and the fuel flow rate control section 103. do. Based on these, predict the future furnace temperature and billet temperature, and in temperature increase pattern calculation 3, determine the temperature increase pattern taking into consideration energy saving, etc., and calculate the furnace temperature setting using the calculation results of 1, 2, and 3 as input. 4 to determine the furnace temperature setting. In this way, the furnace temperature setting function section 106 gives the determined set value to the fuel flow rate control section 103, and the furnace temperature measurement section 104 is heated by the burner 105 and the fuel flow rate is adjusted so as to reach the set value.

〔Effect of the invention〕

As explained above, in this invention, the furnace temperature setting value of each slab is multiplied by the weighting coefficient for furnace temperature setting, and the weighted average value is set as the set furnace temperature. There are effects such as being able to bake averagely or preferentially a certain piece of steel with a targeted temperature increase pattern.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram showing the division of furnace temperature calculation zones in the heating furnace, Figure 2 is a conceptual diagram of determining the correction value for the furnace temperature set value,
FIG. 3 is an overall configuration diagram showing one embodiment of the present invention. 1...Current temperature calculation, 2...Future temperature calculation, 3
... Temperature increase pattern calculation, 4 ... Furnace temperature setting calculation, 1
06... Furnace temperature setting function section.

Claims (1)

[Scope of Claims] 1. A continuous heating furnace composed of a plurality of zones, which has a function of calculating the furnace temperature of each zone and the temperature of the steel pieces in the furnace, and In order to bake on average or preferentially the required number of billets according to the temperature increase pattern of each billet determined from the viewpoint of energy saving, etc., a weighting coefficient for furnace temperature setting is added to the furnace temperature setting value of each billet. A control method for a continuous heating furnace, characterized in that a multiplicative weighted average value is set as a set furnace temperature. 2. In order to determine the furnace temperature setting value for each slab, the position of the control thermometer and the furnace temperature setting position of the slab are taken into consideration, and the furnace temperature setting at that position is reconverted and the new furnace temperature for each slab is determined. A method for controlling a continuous heating furnace according to claim 1, characterized in that the furnace temperature is set to a set value.