JPH0485392A - Heat input control in coke oven - Google Patents

Abstract

PURPOSE:To stabilize the quality of coke and lower the heat quantity of carbonization by making the temp. of discharged coke constant by a specified method using a model for predicting the temp. of coke after carbonization based on the quantity of charged coal, its water content, the oven temp. and the duration of carbonization. CONSTITUTION:In the production of shaft furnace coke in a coke oven having a plurality of kilns, a modellized correction is computed from the actual coke temp. measured at the time of discharging the coke on the basis of a model for predicting the temp. of coke after carbonization from the quantity of charged coal, its water content, the oven temp. and the duration of carbonization. Using the correction, an oven temp. necessary for attaining the intended coke temp. is determined based on the actual quantity of charged coal, its water content and the designed duration of carbonization. By controlling the heat input, the oven temp. is adjusted to the intended value, and the temp. of discharged coke is stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a combustion control method for reducing variations in coke quality and carbonization heat in a coke oven having a plurality of ovens. This invention relates to a method of controlling the amount of heat input to keep the temperature constant.

BACKGROUND OF THE INVENTION The quality of blast furnace coke has a great influence on blast furnace operation. For this reason, it is extremely important to adjust coke quality to a predetermined value and to reduce quality variations. Furthermore, in the operation of a coke oven, reducing the variation in the amount of heat of carbonization leads to stable operation and significant energy savings, so it is important to appropriately control the amount of heat input.

Blast furnace coke is generally manufactured in a coke oven having a plurality of ovens, and the coke quality is controlled by combustion control in the coke oven.

Conventional combustion control methods define the coke oven fire-off time using an index that can automatically detect the fire-off time, and adjust the amount of heat input (furnace temperature ) (Japanese Unexamined Patent Publication No. 57-1598
Publication No. 77, etc.) is - boat fishing.

As a control method to keep the fire-off time constant, the target fire-off time is determined based on the relational expression between the fire-off time, furnace temperature, charged coal amount, charged coal moisture content, and charged coal volatile content. A method is known in which the furnace temperature is calculated and the amount of heat input is controlled so as to reach the target furnace temperature (Japanese Patent Application Laid-Open No. 159877/1983).

In the operation of a coke oven, by making the fire-off time constant, the carbonization situation can be made constant, so it is possible to extend the fire-off time within the carbonization time and reduce the amount of carbonization heat by reducing the variation in the fire-off time. Moreover, by making the carbonization situation constant, variations in coke quality are also reduced.

Incidentally, "fire-off" is defined by the temperature and concentration of gas generated during the process of coking coal, but it is extremely difficult to accurately estimate the fire-off time. For this reason, it is very difficult to make the fire fall time constant, and it cannot help but be unclear.

Therefore, it is difficult to estimate accurately, and with conventional coke oven furnace temperature adjustment or combustion control methods that use the uncertain fire-off time as a controlled variable, it is difficult to estimate the The reality is that combustion management cannot be said to be adequate.

Problems to be Solved by the Invention In view of the above-mentioned actual situation, the present invention has been developed to replace the conventional combustion control method using the fire fall time as a controlled variable.
This paper attempts to propose a method for controlling the amount of heat input into a coke oven that stabilizes coke quality and reduces the amount of heat of carbonization by keeping the temperature of discharged coke constant, which is a clear index of carbonization in coke oven operation.

Means for Solving the Problems The gist of this invention is to use a model that estimates the coke temperature after carbonization from four elements: charging coal amount, charging coal moisture, furnace temperature, and carbonization time, and to measure it at the time of coke discharge. Calculate the model correction amount from the measured coke temperature value, calculate the furnace temperature to achieve the target coke temperature from the three elements of actual charging coal amount, actual charging coal moisture, and planned carbonization time, and adjust the furnace temperature to achieve the target coke temperature. This is a method of controlling the amount of heat input, and also uses the estimation model to find a certain position in the kiln where the coke center temperature reaches the target value from the planned operating conditions of the amount of charged coal, the moisture content of the charged coal, and the carbonization time. In this method, the coke temperature is determined, and the amount of heat input is controlled so as to reach the coke temperature.

In order to keep the target coke temperature after carbonization constant, a means to accurately estimate the temperature is required. Therefore,
This invention uses a model that divides the coking chamber and combustion chamber of a coke oven in the oven width direction and simulates heat transfer from the combustion chamber to coal and coke.

Figure 1 shows the heat transfer simulation model.

This model is a one-dimensional model in the furnace width direction based on one-dimensional heat flow from the combustion chamber to the coking chamber, with heat conduction within the bricks and coal seam, and radiation between the brick wall and the coal seam surface. Regarding the coal seam, the heat of vaporization of the contained moisture is taken into consideration.

Heat transfer calculations are performed using a heat transfer difference equation based on the heat balance equation for each mesh.

The heat transfer simulator can be expressed as a function as follows.

Tc=T-(w, m, T+
Temperature of discharged coke at a certain location in the kiln (e.g. surface) (C) W° Charging coal amount (ton) m, Moisture (%) Tf, Furnace temperature (C) t: Carbonization time (hr) Figure 2 shows this. 3 shows the control flow of the invention.

(I) Target discharged coke temperature calculation Calculate the flue temperature TIc at which the target discharged coke center temperature is achieved using a heat transfer simulator.

The = T++ (Te” T, (w, m, T+
, B)) Tf: Actual furnace temperature (''C) Te Target discharge coke center temperature ('C) w8: Planned coal loading (ton) m Planned moisture content (%) t Planned carbonization time (hr) .゛Furnace temperature Let the heat transfer simulator estimated discharged coke temperature T, (w", mo, Trc, t") with respect to the furnace temperature range for effect calculation (° C.) T le' be the target discharged coke temperature Tw.

(■) Modify the simulator correction amount based on the heat transfer simulator feedback meter jE results.

δ=? 10G'+f〒w −Tw (w, m, 〒t, t
) -J')δ゛Heat transfer simulator correction amount ('C) δ δ up to previous charge (''C) GI° correction gain (-) T, Radiation thermometer measurement value at coke discharge ('C) W: Actual installation Coal amount (ton) F: Actual moisture content (%) Tf: Actual furnace temperature (℃) D: Actual carbonization time (hr) (III) Target furnace temperature calculation Calculate the furnace temperature to achieve the target discharge coke temperature by heat transfer Determine based on the simulator and correction amount.

(IV) Calculation of target furnace temperature The first TI is assumed to be T++'' and calculated using the following formula.

ΣEFJ To: Target furnace temperature ('C) Target furnace temperature ('C) according to TxIj number Wj: Weighting coefficient (-) (V) Calculation of input heat amount Once the target furnace temperature is determined, use the following formula. Based on this, the amount of heat input is calculated, and the opening degree of the fuel valve of the furnace group is adjusted using the fuel valve opening adjustment device of the furnace group so that the amount of heat input is calculated.

Q = to (T"-T) + 2Σ(T" T) K3
T K4△TQ, input heat amount (kcal/hr) T, actual furnace temperature ('C) To, target furnace temperature ('C) △T: amount of increase in actual furnace temperature ('C) K r -K -: Coefficient Note that if the amount of heat input can be controlled for each kiln, it is of course not necessary to control via the above-mentioned target furnace temperature.

Examples Example 1 Figure 3 shows the in-charge accuracy of the heat transfer simulator, and shows the change in temperature in the coal from charging to extrusion.
This is the result of comparing actual values and calculated values. As is clear from this figure, the actual values and calculated values match very well.

Example 2 Figure 4 (A) shows the accuracy of estimating the temperature of discharged coke by the heat transfer simulator, and shows the changes in the center temperature of discharged coke and the surface temperature of discharged coke when operating under the operating conditions shown in Figure (B). This is the result of comparing the actual value and the estimated value, and the trends in the actual value and estimated value match very well.

Example 3 FIG. 5(A) shows the results when the furnace temperature was controlled by applying the method of this invention, and FIG. 5(B) shows the results when the furnace temperature was not controlled.

As is clear from the results shown in Figure 5, by applying the method of this invention to control the furnace temperature, the variation in temperature of discharged coke (
σ) was able to be significantly reduced from 18°C to 6°C.

From this result, it was confirmed that the temperature of discharged coke could be made constant by controlling the furnace temperature by applying the present invention.

As described in detail of the invention, according to the method of this invention, it is possible to reduce variations in the temperature of discharged coke, so it is possible to lower the surface temperature of discharged coke and the center temperature of discharged coke, and the amount of heat of carbonization can be reduced. At the same time, coke quality can be stabilized, and compared to conventional combustion control methods in which fire-off time is a controlled variable, this method has great effects in reducing carbonization heat consumption and achieving stable production.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the heat transfer simulator model of the present invention, Fig. 2 is a block diagram showing the control flow of the invention, and Fig. 3 is a diagram showing the intra-charge accuracy of the heat transfer simulator in the embodiment of the invention. , Figure 4 is a diagram showing the estimation accuracy of discharged coke temperature by the heat transfer simulator, and Figure (A)
is a diagram showing a comparison between the actual value and the estimated value, Figure (B) is a diagram showing the operating conditions in the same example, and Figure 5 (A) is the result when controlling the furnace temperature by applying this invention method. The figure shown in FIG. 2B is a diagram showing the results in the case of no control. Figure 5 (A)

Claims (1)

[Claims] 1. Using a model that estimates the coke temperature after carbonization from the amount of charged coal, the moisture content of the charged coal, furnace temperature, carbonization time, etc., the model correction amount is calculated based on the coke temperature measurement value measured at the time of coke discharge. calculation, actual amount of charged coal, actual amount of charged coal, and planned carbonization time.
A method for controlling the amount of heat input into a coke oven, characterized in that the furnace temperature for achieving a target coke temperature is determined from two factors, and the amount of heat input is controlled so as to reach the furnace temperature. 2 Using a model that estimates the coke temperature after carbonization from the amount of charged coal, moisture content of the charged coal, furnace temperature, carbonization time, etc., the coke center 1. A method for controlling the amount of heat input to a coke oven, comprising determining the coke temperature at a certain position in the oven so that the temperature reaches a target value, and controlling the amount of heat input so that the temperature reaches the coke temperature.