JPH02398B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method of controlling furnace temperature when switching the type of fuel used in coke oven operation.

Prior Art Generally, in a coke oven at a steelworks,
A plurality of different types of fuel are often used while switching depending on the supply and demand balance of various types of fuel. In coke ovens with this type of operation, separate combustion devices are installed for each type of fuel.
The height and shape of the flame in the combustion chamber vary depending on the mounting position of the combustion device, such as the burner, and the calorie content of the fuel. On the other hand, the temperature of the combustion chamber, that is, the furnace temperature, is normally measured using a thermocouple attached to the upper part of the combustion chamber, as described in Japanese Patent Publication No. 53-21001, and therefore the temperature of the combustion chamber is measured using a thermocouple attached to the upper part of the combustion chamber. If the values are different, even if the furnace temperature itself is the same, the measured value will be different due to the difference in the height and shape of the flame in the combustion chamber.

By the way, the many combustion chambers that make up a coke oven are divided into two groups, and when one group is used for combustion, the other group is used for exhausting smoke, and the heat in the exhaust gas is The smoke is stored in the bricks of the heat storage chamber, and combustion and exhaust smoke are switched at regular intervals.
When the combustion side is switched next, the heat stored in the heat storage bricks is given to the fuel and air supplied to the combustion side. The switching of the fuel type is performed at the time of switching from combustion to exhaust smoke (from exhaust smoke to combustion).

Figures 1 a to c are diagrams showing changes in furnace temperature, etc. before and after switching the fuel type, where the horizontal axis indicates time, period B (times _t1 to _t4 ) is the fuel switching period, and period C ( Time t ₄ ~
_t5 ) indicates a transition period, and period A (before time _t1 ) and period D (after time _t5 ) indicate a stationary period. Curve A in FIG. 1A shows the measured furnace temperature, curve B in FIG. 1B shows the fuel flow rate before switching, and curve C in FIG. 1C shows the fuel flow rate after switching. As shown in curve A in Figure 1a, the measured furnace temperature begins to change from the time the fuel type switch starts.
It stabilizes in the stationary phase.

Generally, furnace temperature is inversely proportional to coal carbonization time under the same operating conditions. In other words, increasing the furnace temperature shortens the coal carbonization time.
Further, since the furnace temperature is proportional to the fuel flow rate, it is necessary to adjust the fuel flow rate so that the furnace temperature becomes the temperature for a predetermined coal carbonization time.

However, in the past, operators manually set the furnace temperature and adjusted the fuel flow rate during the transition period, which resulted in variations in coal carbonization time due to individual differences and unnecessary extension of the transition period, resulting in poor coke oven operation. It was difficult to maintain the In addition, in order to avoid the effect of variations in coal carbonization time on coke production, there is a tendency to set fuel flow rates so that the furnace temperature is higher, and the amount of heat consumed for carbonization per ton of coal is usually higher. It was hot.

OBJECTS OF THE INVENTION The present invention aims to provide a furnace temperature control method for solving the above-mentioned problems when switching fuel types in a coke oven, particularly a method for controlling furnace temperature setting and fuel flow rate adjustment during a transition period. .

Constituent Effects of the Invention The method of the present invention for this purpose is to switch one group of a large number of combustion chambers of the coke oven from combustion to flue gas, and to switch the other group from combustion to flue gas in a coke oven that operates by switching between a plurality of different types of fuel. Switching the fuel type at the time of fuel switching to switch the group from exhaust smoke to combustion, and determining the starting point of the transition period after switching the fuel type from the signal indicating the fuel switching state and the signal indicating the fuel type, At the time of the determination, calculate the average value of the furnace temperature measurements within a certain period of time before switching the fuel, and based on the calculated average furnace temperature value, set the furnace temperature under the fuel after switching the fuel type. Calculate a set furnace temperature for a transition period at which the furnace temperature measurement value becomes the furnace temperature set value after a certain period of time from the start point of the transition period;
This is a furnace temperature control method when switching the type of fuel in a coke oven, characterized in that the fuel flow rate is controlled by calculating the fuel flow rate for the set furnace temperature during the transition period.
The present invention will be described in detail below based on examples.

FIG. 3 is a block diagram showing the configuration of an apparatus in an embodiment of the present invention. In the figure, 1 is the starting point (time
t ₄ ), 2 is a circuit that calculates the average value of the furnace temperature measurements within a certain period of time before fuel switching according to the signal from the judgment circuit 1, and 3 is a circuit that determines the setting in the transition period c This is a circuit for calculating the furnace temperature, and 4 is a circuit for calculating the fuel flow rate corresponding to the set furnace temperature.

Next, the operation of the apparatus having the above configuration will be explained. A certain sequence is determined in advance for turning on and off the fuel when switching from combustion to exhaust smoke (or from exhaust smoke to combustion) in the combustion chamber mentioned above, including reducing and increasing the flow rate, and the sequence is determined in advance. As a result of this work, a signal indicating the state of fuel switching as shown in FIG. 2 is obtained. Time t ₁ in the figure is the start point of the reduction in the amount of fuel currently being burned, and at the same time as the reduction starts, the signal indicating "combusting" up to that point changes to a signal indicating "switching" based on an input from the operator. After a certain period of time (there may be some delay depending on the furnace condition, etc.), fuel supply after switching is started at the discretion of the operator, and at the same time, the operator inputs the start of fuel supply. The amount of fuel is increased at a constant rate from the fuel supply start time _t3 to time _t4 , which is a certain period of time later. The signal D indicating the state of fuel switching changes from "switching" to "combusting" again after a certain period of time from time _t3 . On the other hand, the signal indicating the fuel type is, for example, a "signal" indicating the fuel type before fuel switching.
is set as "+1", and the signal indicating the different fuel type after switching is set as "0", and as shown in _FIG . The signal is switched to 0''.

The fuel switching operation in the present invention is performed according to such a sequence, but in conventional operation, after switching the fuel type at time t3, the fuel switching operation is performed at time _t3 .
The furnace temperature setting and fuel flow rate adjustment during the transition period from t ₄ to t ₅ were all manually operated by the operator, but in the present invention, these are automatically controlled.

In the present invention, first, the starting point _t4 of the transition period when the fuel type is switched is detected using the signal D indicating the fuel switching state and the signal E indicating the fuel type. In this embodiment, the determination circuit 1 samples the signal indicating the fuel type at short intervals (for example, every 5 minutes) from the time when the signal 2 indicating the fuel switching state changes from "combusting" to "switching". , the previous fuel type signal (Fl) and the current fuel type signal (Fc)
When Fl≠Fc, it is determined that the fuel type has been switched at the same time as the combustion in the combustion chamber is switched to exhaust smoke (exhaust smoke to combustion), and the fuel switching status signal N during this switching period is determined to have occurred. The time of change from "switching" to "combusting" is determined to be the starting point _t4 of the transition period. Then, a detection signal at the start point of this transition period is output to the average furnace temperature calculation circuit 2. Next, when the start point of the transition period is detected, the average value of the furnace temperature measurements before switching the fuel type is calculated.

The average furnace temperature calculation circuit 2 temporarily stores the measured value signal A from the furnace temperature measuring device, and upon receiving the transition period start point detection signal from the determination circuit 1, calculates the value at time t ₁ .
Calculate the average value _A of the furnace temperature measurements over a certain period of time (for example, the last 3 hours) during the previous steady period A, and calculate the average furnace temperature _A before fuel type switching.
is output to the set furnace temperature calculation circuit 3. Next, the set value of the furnace temperature after the fuel type switching corresponding to the average furnace temperature before the fuel type switching is calculated, and the end point of the transition period (the time after a predetermined period of time from the start point _t4 of the transition period) is calculated.
At t ₅ ), the set furnace temperature in the transition period C is calculated so that the measured value of the furnace temperature becomes the calculated furnace temperature set value. The set furnace temperature calculation circuit 3 calculates the set furnace temperature in the transition period C using the following formula.

θ _i = θ _t4 + θ _B −θ _t4 /Tc・i ...(1) θ _i : Set furnace temperature at the i-th time from the transition period start point t ₄ θ _t4 : Measured value of the furnace temperature at the transition period start point t ₄ θ _B : Calculated using the following formula with the furnace temperature setting value in the steady period D after switching the fuel type θ _B = k ₁ · _A + k ₂ k ₁ and k ₂ are constants determined by the type of fuel to be switched Tc: Time of the transition period C The set furnace temperature for the transition period C calculated at this point, that is, the starting point _t4 of the transition period C, is as shown in FIG. FIG. 4 shows an example of the set furnace temperature calculation results when the transition period is 5 hours. This example is an example in which the set furnace temperature is calculated every hour and a stepped temperature gradient is given, but the time interval for calculating the set furnace temperature is not limited to every hour, and the temperature gradient is continuously calculated. You can also give it to someone. Next, the set furnace temperature θ _i calculated by the above equation (1) is input to the fuel flow rate calculation circuit 4, and the fuel flow rate corresponding to the temperature gradient is calculated and output to a combustion control device (not shown). Thus, by controlling the fuel flow rate in accordance with the temperature gradient shown in FIG. 4, the furnace temperature becomes the temperature corresponding to the switched fuel at the end of the transition period, and a smooth transition to the steady state is achieved.

In addition, in the present invention, the furnace temperature for the above-mentioned transition period is not only set at the start point of the transition period, but also at appropriate time intervals (for example, 60 minutes) during the transition period based on the furnace temperature measurement at that point _in time. The following formula θ _j = θ _to + θ _B −θ _to /Tcn・j ...(2) θ _j : Set furnace temperature at j-th hour from the current time t _o θ _to : Measured value of the furnace temperature _at the current time t Tcn: From the current time By sequentially correcting the temperature gradient shown in Fig. 4 based on the time until the end of the transition period and sequentially correcting the fuel flow rate, it is possible to further increase the accuracy rate of the furnace temperature set point at the end of the transition period. .

Effects of the Invention As described above, the present invention suppresses the variation in coal carbonization time by automatically controlling the combustion during the transition period when switching fuel types in a coke oven that uses multiple types of fuel while switching. It has the excellent effect of lowering the amount of heat consumed per carbonization and maintaining stable coke oven operation.

[Brief explanation of drawings]

FIG. 1 is a diagram showing changes in furnace temperature, etc. when switching fuel types in a coke oven, FIG. 2 is a diagram showing fuel switching state signals and fuel type signals, and FIG. 3 is a diagram showing the configuration of an embodiment of the apparatus of the present invention. The diagram shown in FIG. 4 is a diagram showing the set furnace temperature during the transition period in the embodiment of the present invention. 1: Transition period start point determination circuit, 2: Average furnace temperature calculation circuit, 3: Set furnace temperature calculation circuit, 4: Fuel flow rate calculation circuit.

Claims (1)

[Claims] 1 In a coke oven that operates by switching between multiple types of different fuels, fuel switching involves switching one group of the coke oven's many combustion chambers from combustion to flue gas, and switching the other group from flue gas to combustion. At the time, the fuel type is switched, the start point of the transition period after the fuel type switching is determined from the signal indicating the fuel switching state and the signal indicating the fuel type, and at the time of the determination, the start point of the transition period after the fuel type switching is performed. Calculates the average value of the furnace temperature measurements at , and calculates the furnace temperature set value under the fuel after the fuel type switching based on the calculated furnace temperature average value, and calculates the furnace temperature set value under the fuel after the fuel type switching, and calculates the furnace temperature set value under the fuel after the fuel type switching A coke oven characterized in that a set furnace temperature in a transition period in which a measured value of the furnace temperature later becomes the furnace temperature set value is calculated, and a fuel flow rate is calculated for the set furnace temperature in the transition period to perform fuel flow rate control. Furnace temperature control method when switching fuel types.