JPH10226808A - Method for controlling combustion of hot stove - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize the control of charged calory in developing trouble in an equip ment and to hold a prescribed blasting temp. by obtaining the necessary combustion gas quantity to supplement the shortage of combustion time in the following process with calculation to execute the combustion when the measured value of the changing time from the completion of blasting to the start of combustion is shorter than the usual charging time. SOLUTION: The changing time t2 from the completion of blasting to the start of combustion, is measured and this measured value and the usual charging time t1 are compared and at the time of being t1 <t2 , in order to supplement the shortage of the combustion time in the following process caused by the changing time difference, the necessary combustion gas quantity to obtain the required charging calory, is obtd. from the equation by using the changing time difference to execute the combustion. At the time of being the normal time without any trouble in the equipment, t1 =t2 . In the case of developing the trouble in the equipment, usually, since an operator takes the counter-measure to the trouble, the changing time becomes longer than the usual time, i.e., t1 <t2 , and the changing time difference is considered as a negative factor to the necessary combustion time in the following process. Then, the negative factor of the necessary combustion time is supplemented with the increase of the combustion gas quantity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling combustion in a hot blast stove of a blast furnace, and more particularly to a method for controlling combustion when equipment trouble occurs.

[0002]

2. Description of the Related Art In the operation of a hot blast stove, if the amount of heat input during the combustion period is insufficient, the specified blast temperature cannot be maintained during the blast period, which hinders the smooth operation of the blast furnace. Conversely, if an excessive amount of heat is input, the amount of heat that can be effectively used as blast furnace air will be input, and the heat loss associated with the exhaust gas will increase, the heat loss from the furnace body will increase, and the thermal efficiency will increase. Causes a decrease in

[0003] Therefore, various methods have been proposed for maintaining a predetermined blowing temperature to protect the furnace body and improve the thermal efficiency. For example, Japanese Patent Publication No. 64-9375 discloses a combustion control method for protecting a furnace body and improving thermal efficiency by measuring the temperature of a brick portion of a hot blast stove and supplying a fuel so as to exceed a control lower limit temperature. Proposed. This method calculates the required combustion gas amount by controlling the temperature measurement value of the brick portion at the time of the completion of the ventilation, controls the amount of heat input, and
In this method, calorie control is performed at regular intervals to adjust the amount of combustion gas during combustion in order to prevent a change in the amount of heat input due to a change in the calorie value of the combustion gas.

[0004]

However, conventional combustion control techniques, including the above-described method for controlling the combustion of a hot stove, have a shortfall in the amount of heat input when a required set combustion time cannot be secured due to equipment troubles in the hot stove. Is not provided with a system for automatically correcting For this reason, in the past, the operator corrected the combustion time to ensure the set blast temperature at the time of equipment trouble.However, appropriate correction may not be performed due to individual differences, and the thermal efficiency of the hot blast stove and the control of input heat quantity May worsen.

The equipment trouble of the hot stove occurs when the hot stove is switched because most of the valve malfunctions occur. For example, no. (1) If a malfunction of the valve occurs when switching from blowing the hot stove to combustion, the operator rushes to the site to take measures against the equipment trouble, and as a result, the switching time is longer than usual (about 10 minutes) That would be. If this switching time is long, the combustion time of the next process is shorter than usual, insufficient combustion occurs, and the set blowing temperature cannot be secured when the blowing process is started, and the silica brick seam temperature at the end of the blowing is the lower limit value ( 530 ° C.). In order to prevent this, the operator switches the operation of the hot blast stove from automatic to manual to perform the furnace operation. However, as described above, there is a case where an appropriate correction is not performed because there is an individual difference in a method of operating a furnace by an operator.

The present invention has been made in view of the above-mentioned problems of the prior art. By automating the furnace operation when a trouble occurs in the hot stove, the hot stove can be inserted even when the trouble occurs. Stabilize heat control,
An object of the present invention is to propose a combustion control method for a hot blast stove capable of maintaining a predetermined blast temperature.

[0007]

SUMMARY OF THE INVENTION A method of controlling combustion in a hot stove according to the present invention is a method for compensating for a shortage of combustion time due to the occurrence of equipment trouble in a hot stove by increasing the amount of combustion gas in the next step. the switching time t ₂ from the blower complete until the start of combustion is measured, and compared with the measured values and the normal switching time t _1, t 1 _<to compensate for burn time shortage of the next step by the switching time difference at t ₂ Using the switching time difference, the amount of combustion gas required to obtain a required amount of input heat is obtained by the following equation 1, and combustion is performed.

[0008]

During the operation of the hot blast stove, t ₁ = t ₂ in a normal state without any equipment trouble. However, when an equipment trouble occurs, the switching time is longer than usual because the operator takes the trouble treatment as described above, and t ₁ <t ₂ , and the switching time difference is the required combustion time of the next process. It will be minus minutes. In the present invention, the minus part of the required combustion time is supplemented by an increase in the amount of combustion gas.

In the present invention, the switching time t _{2 to be} measured is
Is only the switching time from the completion of the ventilation to the start of combustion for the following reason. If equipment trouble occurs during switching from the completion of combustion to the start of blowing, and the switching time becomes longer, the blowing time in the next process becomes shorter, resulting in a margin of heat input. However, if the switching time from the completion of combustion to the start of air blowing becomes longer, the single air blowing time of another hot air stove becomes longer during this time, and the calorific value of the hot air stove is used considerably during this time. When the equipment trouble measures that occurred during the switching from the completion of combustion to the start of ventilation are completed, and when the ventilation is switched to parallel ventilation at the completion of switching, the switching time from combustion completion to the start of ventilation becomes longer, resulting in a longer single ventilation time Since the shortage of the calorific value of the hot stove is almost compensated for by the calorific value of the hot stove with sufficient heat, the switching time from the completion of combustion to the start of the blow is not measured in the present invention.

[0011] As described above, by measuring the switching time t ₂ until the start of combustion from blowing completed, by comparing the normal switching time t _1, by deterioration of the switching time due to equipment trouble required heat input in the combustion of the next step Since the minus portion can be grasped, by automatically correcting the minus portion with the amount of combustion gas, even if an equipment trouble occurs, the combustion control can be automatically performed without the operator intervening in the combustion control. Therefore, in the combustion control in the hot blast stove, stable combustion control can be performed even if disturbance due to equipment trouble occurs.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic diagram showing an outline of a hot blast stove for a blast furnace and a system for controlling the amount of input heat, and FIG. 2 is an explanatory view showing a combustion control method for the hot blast stove according to the present invention.
Is a hot blast stove, 2 is a blast furnace, 3 is a blower, 4 is a computer, 5 is a fuel supply controller, 6 is a thermometer, 7 is a calorie meter, and V ₁
Gas (fuel) valve, _{V 2} is the air valve, _{V 3} are blowing valve, _{V 4}
The mixing cold air valve, _{V 5} is Neppuben, _{V 6} is a flue valve.

As is well known, the hot blast stove 1 performs combustion with M gas and air in a combustion chamber, heat generated by the combustion is stored, and when the temperature in the heat storage chamber rises to a predetermined value and the combustion process is completed, blow valve V _3, open the Neppuben V _5, through the cool air sent from the blower 3 in a hot-air oven 1, and sends the hot air to the blast furnace 2 is adjusted by mixing cool air valve V ₄ to blast temperature setting.

The heat quantity control of the hot blast stove is performed by measuring the temperature of the silica seam at the time of completion of the air blowing with the thermometer 6, taking the value into the computer 4, and comparing it with the lower limit value of the silica seam temperature (530 ° C.). calculates the next amount of combustion gas, via a fuel supply amount adjusting meter 5 for controlling the gas (fuel) valve V _1. The setting of the combustion gas amount is set immediately before the start of combustion, and thereafter, the calorie of the combustion gas is taken into the computer 4 in a one-minute cycle, and the calorie counter 7
The calorie control is performed by comparing and correcting the calorie actually measured.

The set blowing temperature is ensured by the operator arbitrarily setting the combustion time and the blowing time. For example, when the set air temperature is high, the combustion time is lengthened, and when the air temperature is low, the combustion time is shortened.

In the operation of a hot-blast stove in which combustion control is performed by the above-described method, for example, when a malfunction of a valve occurs at the time of switching from blowing of a hot-blast stove to combustion, an operator has conventionally rushed to the site to deal with the problem. Therefore, the switching time is longer than usual, and as a result, the combustion time of the next process becomes shorter than usual, resulting in insufficient combustion. In order to prevent difficulty in securing the temperature, the operator switched the operation of the hot blast stove from automatic to manual, and corrected the combustion time for securing the set blast temperature. However, in this conventional method, an appropriate correction may not be performed due to an individual difference of an operator, and the thermal efficiency of the hot blast stove and the control of the input heat quantity may be deteriorated.

Therefore, in the present invention, as shown in FIG. 2, the switching time from the completion of the ventilation to the start of combustion (the charging time of the hot-blast stove and the switching time of the valve) are set as shown in FIG. the combined means the time) t ₂ is measured using a timer, determines the difference (t ₂ over t ₁₎ between the switching measured time t ₂ and the normal switching time t _1, the required heat input by the formula 1 Is calculated by the computer 4 to secure the combustion gas amount. When t ₁ = t ₂ , the equipment trouble is zero. However, when t ₁ <t ₂ , the switching time becomes longer due to equipment trouble, and the required combustion time becomes insufficient. Therefore, the shortage of the required combustion time is eliminated by increasing the amount of combustion gas. I do. That is, the combustion gas in the next step a combustion gas amount obtained by the equation (1) using the difference between the switching measured time t ₂ and the normal switching time t ₁ from the blower complete until the start of combustion during equipment trouble in the present invention Set as quantity. When the combustion gas quantity in the next step is set this way, the gas valve V ₁ through a fuel supply amount adjusting meter 5 is controlled. Therefore, even in the case of equipment trouble, the control of the amount of heat input to the hot stove is stabilized, so that the silica seam temperature can be stabilized and the blowing temperature can be stabilized.

In the automatic control, the switching time from the completion of the ventilation to the start of the combustion and the switching time from the completion of the combustion to the start of the ventilation are fixed values, and the combustion time in the combustion process and the ventilation time in the ventilation process are fixed. , And is variable by a series of cycle time set values with values from the schedule control. The cycle time is determined by obtaining the required combustion time from the set air temperature.

[0019]

FIG. 3 is a diagram showing an example of a transition of a silica stone joint temperature (at the time of completion of blowing) in an actual hot blast stove in a normal state. The silica seam joint temperature, which is the control temperature for controlling the amount of heat input to the hot blast stove, is controlled at or above the lower limit (530 ° C.), and the temperature at the time of completion of blowing is the lowest. The right side in the figure is the latest data, and the data on the left side is the past data. Normally, stable control is performed without much lowering than 530 ° C. as shown in FIG. 3 by controlling the amount of heat input to the hot blast stove.

FIG. 4 shows an example of transition of the quartzite seam temperature at the time of occurrence of equipment trouble, in which equipment trouble has occurred, and further, the furnace operation by the operator has failed. In other words, because the switching time from the completion of the air supply to the start of combustion is increased due to equipment trouble, a shortage of combustion time occurs, and the shortage of combustion cannot be compensated for, resulting in the completion of the next process. This is an example in which the quartzite seam temperature is significantly lower than the lower limit.

Thereafter, recovery was attempted by the conventional control of the amount of input heat. However, it takes seven cycles counted from the occurrence of equipment trouble until the silica seam temperature stabilizes, and the hot blast stove schedule is usually about 180 minutes per cycle. It takes 21 hours (3 hours x 7) to recover. Thus, once the temperature falls below the lower limit, recovery takes a considerable amount of time, and the amount of gas used for the recovery becomes enormous. Further, in a state where the temperature of the silica stone seam is lowered, the required blowing temperature cannot be secured.

FIG. 5 shows a case where the same equipment trouble occurs as described above.
It is an example of transition of the silica stone joint temperature comparing the case where this invention method is implemented, and the case where it is not implemented. As is clear from this figure, when the present invention method was not carried out, the next silica seam temperature was significantly lower than the lower limit control value (530 ° C.). Is stable without deterioration. That is, it can be seen that when the present invention method is not performed, the input heat amount control is deteriorated, whereas when the present invention method is performed, the input heat amount control can be stabilized.

[0023]

As described above, according to the method of the present invention, equipment trouble occurs because the minus amount of required heat input in combustion in the next process due to deterioration of switching time due to equipment trouble is automatically corrected by the amount of combustion gas. This not only stabilizes the thermal efficiency of the hot-blast stove and the control of the amount of heat input, but also allows the operator to automatically control the combustion without intervening in the combustion control, greatly reducing the workload of the operator. It has a great effect of being performed.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an outline of equipment of a hot blast stove for a blast furnace and an input calorific value control system.

FIG. 2 is an explanatory diagram showing a combustion control method for a hot blast stove according to the present invention.

FIG. 3 is a diagram showing an example of transition of a normal silica seam temperature (at the time of completion of blowing) in a hot blast stove.

FIG. 4 is a diagram showing a transition example of a silica stone joint temperature when a facility trouble occurs in a hot blast stove, showing an example in which a facility trouble has occurred and a furnace operation procedure by an operator has failed.

FIG. 5 is a diagram showing an example of transition of a silica stone seam temperature comparing a case where the present invention method is performed with a case where the present invention method is not performed when a facility trouble occurs in a hot blast stove.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 hot blast stove 2 blast furnace 3 blower 4 calculator 5 fuel supply controller 6 thermometer 7 calorie meter V ₁ gas (fuel) valve V ₂ air valve V ₃ blower valve V ₄ mixed cold air valve V ₅ hot air valve V ₆ flue valve

Claims (1)

[Claims] 1. A combustion control method at the time of equipment trouble occurs in a hot air furnace blast, the switching time t ₂ from the blower complete until the start of combustion is measured, the measured values and the normal switching time t ₁
In order to compensate for the shortage of combustion time in the next step due to the switching time difference when t ₁ <t ₂ , the switching gas difference is used to calculate the amount of combustion gas necessary to obtain the required heat input by the following equation. A combustion control method for a hot blast stove, wherein the combustion is performed.