JPS6365230A - Burning control method for hot air furnace - Google Patents

Abstract

PURPOSE:To accurately respond to conditions of following hot air blowing to a blast furnace and perform an efficient burning control in the furnace by determining the feed rates of and feed ratio between fuel gas and burning air based on the predicted flame temperature so as to control the burning in the furnace. CONSTITUTION:The dome temperature in the ending stage of air blowing and hot air supply conditions to the blast furnace (blowing temperature, blowing rate, blowing time) up to the preceding operation are memorized in a CPU as process data. Meanwhile, the regression coefficient is determined by performing multiple-regression analysis. In the CPU by using certain flame temperature predicting formulae. Next, the target flame temperature for the following operation is predicted based upon hot air supply conditions to a blast furnace desired for the following operation and the dome temperature in the ending stage of the preceding operation. Further, the required quantity for the burning is computed from the burning time period of the furnace and the hot air supply conditions to the blast furnace, and the fuel gas quantity, burning air quantity and air/fuel ratio are determined from the target flame temperature and the required calorific value for the burning. These values are taken into account to make an overall judgment before the following burning. This way, the accuracy of prediction of the flame temperature can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for controlling the operation of a hot blast furnace for supplying hot air blown from the tuyere of a blast furnace. The present invention also relates to a method capable of efficiently and accurately controlling the supply amount and supply ratio of combustion air.

[Prior Art] FIG. 2 is an explanatory diagram showing an example of the configuration of a hot blast furnace 1. The hot blast stove 1 is configured by connecting a combustion chamber 2 and a heat storage chamber 3, and usually there are 3 to 3 units per blast furnace. A four-tower hot air stove is also installed. A checker brick is incorporated inside the heat storage chamber 3, and the combustion gas generated in the combustion chamber 2 is brought into contact with the checker brick to store heat. The piping connected to the heat storage chamber 3 and the combustion chamber 2 is divided into the following systems (a) to (d).

(a) Cold air system Cold air forced from a blower (not shown) is introduced into the heat storage chamber 3 through the cold air pipe 9, and is brought into contact with checker bricks that have high heat to remove heat! M- Warm and supply to the hot air system described below. The mixed cold air pipe 10 is provided for the purpose of bypassing cold air from before the hot blast furnace 3, feeding it to the hot air system via the plasto mixer 11, and adjusting (adjusting in the direction of lowering) the temperature of the air blown to the blast furnace. .

(W) Hot air system High temperature air sent from the aforementioned cold air system via the heat storage chamber 3 is sent to the blast furnace via the hot air pipe 8.

(c) Fuel dregs supplied from the combustion system fuel gas pipe 6 and the combustion air pipe 5
Combustion air supplied from the combustion chamber 2 is guided to the combustion chamber 2 and combusted, and the hot air (combustion gas) generated by the combustion is introduced into the heat storage chamber 3 to store heat in the heat storage chamber 3.

(d) Heat is applied to the waste gas system checker brick, and the waste gas whose temperature has been lowered is discharged from the flue pipe 4.

In the operation management of a hot blast furnace, the amount of heat generated in the combustion system shown in (c) above is controlled by taking into account the amount and temperature of hot air required for blowing into the blast furnace. This is generally done by the method described below.

In other words, as shown in Figure 3, the blast furnace situation (actual results, actual situation).

Calculate the required amount of accumulated heat in the hot air furnace 1 of one tower from the next hot air blowing amount, blowing time, and air blowing temperature, which are determined based on the management goals, etc. Determine the temperature. Next, the amount of fuel gas, amount of combustion air, and fuel gas/air supply ratio (hereinafter simply referred to as air-fuel ratio) are calculated so that the target dome temperature can be achieved within a specified time, and the target dome temperature is measured using the thermometer 7b. This is a conventional and common method of conducting combustion in the combustion chamber 2 under controlled conditions.

[Problems to be Solved by the Invention] When combustion is performed for the next hot air injection according to the fuel gas amount and air-fuel ratio determined according to the flowchart shown in FIG. Since residual heat in the dome at the end of the combustion period is not taken into account, the accuracy of predicting the next target dome temperature is poor, and the amount of heat stored by combustion is either too much or too little, making it impossible to perform efficient combustion control.

Therefore, the inventor of the tree conducted various research with the aim of accurately responding to the next blast furnace hot air blowing conditions and performing efficient combustion control in the combustion chamber without causing waste. The method of the present invention has been completed.

[Means for Solving the Problems] The method of the present invention that achieves the above object has the following advantages:
The target flame flame temperature for the next combustion is predicted using the blast temperature and the dome temperature at the end of the blast as variables, and the respective supply amounts of fuel gas and combustion air are determined based on the predicted amount of heat required during the combustion period and the flame flame temperature predicted value. The gist is to determine the supply ratio and control combustion in the combustion chamber.

[Function] Every time hot air is blown from a certain hot blast furnace to the blast furnace, the amount of air blown, the air temperature, and the hot air dome temperature at the end of the blowing are collected and stored in a computer, and the information is stored in the computer. The flame flame temperature during combustion in the combustion chamber is
It is calculated from the fuel gas amount, air-fuel ratio, and gas calories and stored in the same way.

Next, with flame flame temperature (FT) [t] as an independent variable, air volume (BV) [Nm'/H] and air temperature (BT).
[t] and the hot air stove dome temperature (DTD) at the end of the blowing period [
t] as a dependent variable, multiple regression analysis is performed using the data of the N times, and regression coefficients are determined for each. For example, the flame flame temperature prediction formula FT=8+・DTD +a2'
Calculate the regression coefficients a1 to a4 from BT+a3@BV+a4 from N times of data, and calculate the regression coefficients a1 to a4.
The flame flame temperature (FT) is calculated using the previous hot blast furnace dome temperature and the next hot air blast volume and blast temperature.
Calculate and predict. Then, in order to achieve this predicted flame flame temperature, combustion is performed by controlling the amount of fuel gas to the combustion chamber, the amount of combustion air, and the air-fuel ratio while taking into account fuel gas calories, etc., and heat storage in the heat storage chamber. Do this.

Therefore, regarding the prediction of the flame flame temperature mentioned above, since the final dome temperature of the previous blast is input as process data, it is possible to make highly accurate predictions that take into account the influence of the residual heat in the heat storage chamber, and to prevent over-combustion of fuel gas. It can be precisely controlled without any shortage. In addition, flame flame temperature prediction is performed for each combustion process, and the regression coefficients are updated one after another, so accurate combustion control can be performed by following operational changes in hot air injection into the blast furnace. Can be done.

[Example 1] FIG. 1 is a flowchart showing an example of combustion control of a hot blast stove according to the present invention.

First, the dome temperature at the end of the blasting period up to the immediate inlet and the hot air supply conditions to the blast furnace (blast temperature, blast flow rate, blasting time) are stored in the CPU as process data, and then the flame temperature prediction formula described in the previous section is used to store the hot air supply conditions to the blast furnace in the CPU. Perform multiple regression analysis to find regression coefficients. Then, the next target flame flame temperature is predicted from the next desired hot air supply conditions to the blast furnace and the dome temperature at the end of the previous blast.

In addition, the required amount for the combustion period is calculated from the scheduled combustion time in the combustion chamber and the hot air supply conditions to the blast furnace, and the amount of fuel gas, amount of combustion air, and air-fuel ratio are determined from the target flame temperature and the required amount of heat for the combustion period. However, the administrator makes a comprehensive judgment based on these values and performs the next combustion operation.

The prediction accuracy of the flame flame temperature by the above method is ±0.01° C. or less compared to the actual estimated value, and it is known that highly accurate calculation prediction is possible.

For example, in the method of determining the target dome temperature according to the flowchart shown in Figure 3, the difference between the predicted flame temperature and the actual calculated value is as much as 18.5 degrees Celsius on average.
When the flame flame temperature is predicted by the method of the present invention shown in FIG. 1, the average difference between the predicted value and the actual calculated value can be made highly accurate to 0.07° C. or less.

Furthermore, the prediction accuracy ratio (predicted value/actual value) of the mixed gas flow rate calculated by the method of the present invention is on average 1.00°: 0
．． 03 can be achieved.

[Effects of the Invention] By the method of the present invention, it has become possible to predict the flame flame temperature with high accuracy, and it has become possible to accurately control combustion in the combustion chamber without excess or deficiency.

Furthermore, since the flame flame temperature can be predicted over time, it is now possible to accurately follow changes in blast furnace operation, ensuring highly accurate combustion.

[Brief explanation of drawings]

FIG. 1 is a flowchart showing a combustion control method according to the present invention, FIG. 2 is an explanatory diagram showing the structure of a hot air stove, and FIG. 3 is a flowchart showing a conventional combustion control method. 1... Hot air stove 2... Combustion chamber 3... Heat storage chamber 4... Flue pipe 5... Combustion air pipe
6...Fuel gas pipe 78-7c...Thermometer 8.
...Hot air pipe 9...Cold air pipe 10...Mixed cold air pipe 11...Plast mixer

Claims (1)

[Claims] In a method for controlling the supply of fuel gas and combustion air in a combustion chamber for storing heat by supplying combustion gas to a heat storage chamber, the next combustion is controlled using the air volume to the blast furnace, the air temperature, and the dome temperature at the end of the air blowing as variables. Predicting the target flame flame temperature in the combustion period, determining the supply amount and supply ratio of fuel gas and combustion air based on the predicted value of required heat during the combustion period and the predicted value of the flame flame temperature, and controlling combustion in the combustion chamber. Characteristic combustion control method for hot air stoves.