JPS5867812A - Operation of cold blast mixing-stop valve in hot stove - Google Patents

Abstract

PURPOSE:To elevate the thermal efficiency of a hot stove at the parallel operation by the plural hot stoves equipped to a blast furnace by a method in which when a cold blast mixing butterfly-valve is fully closed, a cold blast mixing stop valve is also fully closed, and when the degree of opening of the cold blast mixing butterfly valve is controlled, the cold blast mixing stop valve is fully opened. CONSTITUTION:When blast temperature exceeds a predetermined value and the pressure difference between cold blast and hot blast exceeds the controlled value, a cold blast mixing butterfly valve 24 is changed from fully closing to controlled opening and is linked to a cold blast mixing stop valve 22, which is fully opened. When the hot blast- temperature is within the predetermined value, and the pressure difference between cold blast and hot blast is within controlled value, the valve 24 is fully closed and is linked to the valve 22, which is also closed. Thus, according to the above manipulation, following operation is carried out so that when the valve 24 is closed, the valve 22 is also closed, thereby preventing the leakage of the valve 24. Then, when the opening degree of the valve 24 is controlled, the valve 22 is fully opened, so the difficulties such as the temperature control in blast operation by single hot stove and the necessity for a safety device against error-signal remaining in former skills are eliminated, and the controlled opening may be achieved. In figure, number 20 is a blast furnace, 2 is a combustion chamber, 4 is a accumulator and 18 is a cold blast mixing chamber respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for operating a mixed cooling cutoff valve for a hot air stove, and more particularly to a method for operating a mixed cooling cutoff valve for increasing the thermal efficiency of a hot air stove.

A hot blast furnace of a blast furnace will be explained with reference to FIG. The hot air stove is composed of a combustion chamber 2 and a heat storage chamber 4, and the combustion process is performed by a combustion gas valve 6 and #! The first combustion air valve 8 is controlled and the generated combustion gas is released into the atmosphere through the heat storage chamber 4 and the flue valve 10, and the sensible heat of the combustion gas is transferred to the checker in the heat storage chamber 4. Heat is stored in bricks.

The blowing factory passes the cold air from the blower 11 through the cold air butterfly valve 12 and the cold air valve 14 into the heat storage chamber 4, and supplies it to the blast furnace 20 as hot air through heat exchange through the hot air valve 16 and the mixed cooling 1i1B. In order to supply cold air to the mixed cooling chamber 18 and control the temperature of the hot air, the cold air supply path is partially branched and is supplied to the mixed cooling chamber 18 via a mixing cutoff valve 22 and a hot/cold butterfly box 24 that controls the cold air. There is.

Generally, four hot blast furnaces are installed per blast furnace, and in normal operation, a so-called parallel blowing method (staggered parallel method) with two #am process and two blower blowers is carried out.

In this case, the blast furnace temperature - node is cold air butterfly square 1
2, the amount of air passing through the hot-blast stove that sent air to the first hot-blast and the hot-blast hot-blast that sent air to the second hot air is adjusted to the temperature of the passing air, and it is possible to roughly control it with only the cold air butterfly square 12. . Therefore, the mixed cooling butterfly valve 24 is warm IiL! It is almost completely closed except for temperature control when switching over to the hot air stove, which is problematic, and it is rarely activated.

However, due to the characteristics of the mixed cooling butterfly valve 24, there is considerable leakage even in the fully closed state, and since it is a movable valve body, this leakage is unavoidable, and the leaked cold air is used to supply air from the hot air stove. The temperature of the heated air decreases, and the blowing temperature is around 1250'C, which corresponds to a drop of about 20 degrees Celsius.

To prevent this from happening, the mixed cooling butterfly valve 24 is located upstream of the mixed cooling butterfly valve 24 and is used in a fully open state except when the AiF body is in use. A so-called "mixed cooling shutoff valve fully closed operation" in which the cutoff valve 22 is fully closed has been proposed, but when operated using a conventional remote manual circuit (with air blow maintenance interlock included), the following problems arise.

(4) When switching from a hot-blast furnace to a single-air blower temporarily, the blower temperature fluctuates and the cold-air butterfly valve 1
Since control cannot be performed with only 2, control using mixed cold air is required, but if the mixed cooling cutoff valve 22 is fully open, the mixed cold air system cannot be used for control.

@ The cold air safety circuit, which is a safety device against false signals, cannot be used. In other words, in a hot-blast stove, the blower maintenance circuit is not activated except when the air is at rest, and the "blow RIM hold interlock" is activated to control one hot-blast stove so that the cold-air valve 14 and the hot-air valve 16 are always kept fully open. is being carried out. This air blow maintenance inter 4-circuit circuit was created for the purpose of preventing blower nursing failures, symbolic air reduction, depressurization, and prevention of accidents caused by blast furnace tuyeres turning over due to body wind. It is essential for However, even with this ventilation maintenance mechanism, if the opening/closing signals of the cold air valve 14 and hot air valve 16 issued by the operation of the limit switch are false signals, the valve body will close and there is a risk that the above accident will occur. be. Therefore, as a safety device for No. The mixed cooling butterfly valve 2 opens the provided mixed cooling butterfly valve 24 to ensure a minimum air volume through the mixed cooling chamber 18 to prevent accidents caused by the above-mentioned erroneous signals.
4 cold air safety circuits, but if the "mixed cooling cutoff valve fully closed operation" is adopted, this safety device 11 circuit will be destroyed and cannot be used.

In other words, if a conventional remote manual circuit is operated with a fully closed mixed shutoff valve, it will not be possible to respond quickly when mixed cold air is required. It had the disadvantage of being unusable.

An object of the present invention is to solve the problems of the prior art described above and to provide a method of operating a mixed-cooling bell shutoff valve for a hot-air stove, which increases the thermal efficiency of a hot-air stove.

The gist of the present invention is as follows.

That is, in parallel blowing operation of a hot blast furnace, which is provided with a plurality of units for one blast furnace and has a mixed cooling butterfly valve for mixing cold air and a mixed cooling cutoff valve, when the mixed cooling butterfly valve is fully closed, the mixed cooling butterfly valve is closed. When the cold cutoff valve is fully closed and the mixed cooling butterfly valve is controlling the opening, the m? This is a method of operating a hot blast furnace mixed cooling cutoff valve, which is characterized by fully opening a qt cutoff valve.

The operation of the mixed cooling cutoff valve 22 of the present invention can be realized as follows by adding an automatic circuit to the conventional remote manual circuit.

That is, the operation of the mixed cooling butterfly valve 24 is switched from fully closed to opening control when the blowing temperature exceeds the set value and when the pressure difference between the I9 wind pressure and the hot air pressure exceeds the control value,
As described below, the mixed cooling butterfly valve 24 and the mixed cooling cutoff valve 22 are interlocked, and the mixed cooling cutoff valve 22 is fully opened.

On the other hand, when the air temperature is within the set value and the pressure difference between the cold air pressure and the hot air pressure is within the pipe field value, the mixed cooling butterfly valve 24 is fully closed, and the mixed cooling cutoff valve 22 is interlocked and fully closed as shown below. Closed.

The present invention prevents leakage of the mixed cooling valve by following the operation so that the mixed cooling butterfly valve is fully closed when the mixed cooling butterfly valve is closed. At the time of control transition, the mixed cooling cutoff valve is fully opened, so that the problem of safety equipment due to the temperature fIIll# and d4 signal when blowing air from the hot air stove alone in the conventional technique is solved, and the opening degree can be controlled.

Embodiment: Qg - Figure 2 shows a circuit diagram of a solenoid valve provided in the operating pressure circuit of the valve actuating cylinder that operates the mixed cooling cutoff valve. In other words, in addition to the independent air blowing when switching over the hot air stove, the opening and closing of the square provided in the mixed cooling butterfly valve opens only when the temperature is lower than the set temperature, and closes when the air blowing temperature is controlled by opening degree control. Relay AX is installed in each circuit that has contact &-4, which is operated by the limit switch that detects closing, and contact Jl-5, which is activated when air is blown individually, in parallel.

BX is arranged, and each relay contact JIx, which is operated by each relay AX%BXK, controls a pressure air circuit for operating a mixed cooling lf'' 1r square in the circuit covered by each relay contact JIx, bxik.
L-magnetic valves MA and MY are provided, and ■ indicates an automatic/manual switching circuit, and ■ indicates a manual mixed cooling/disconnection switch.

Therefore, when blowing air independently, contacts 1-5 of the 0 circuit are activated, relay contact bx is activated by relay BX, and each solenoid valve M
By energizing A and MY, pressure air is supplied from a pressure air circuit (not shown) to the drive cylinder of the mixed cooling cutoff valve, and the mixed cooling cutoff valve is fully opened. Note that when the mixed cooling shutoff valve is fully open, the contact b-2 is actuated by the open detection of the lift switch that detects whether the valve is open or closed, and the solenoid valve MA is demagnetized to exhaust the above-mentioned supply pressure.

In addition, contact a-4 is activated by the closing signal of the reverse Ka cold butterfly cell.
is activated, relay contact 1x is activated by relay AX, and solenoid valve MA is energized, and the mixed cooling cutoff valve is fully closed by the drive cylinder. Contact b-3 is activated by the detection of mixed cooling cutoff valve closure, and solenoid valve MA is activated. is demagnetized and the supplied pressure air is discharged in the same way as when the valve was opened.

Furthermore, when controlling the opening degree of the mixed cooling butterfly valve, the mixed cooling butterfly 7
') The closing signal of the limit switch that detects the opening and closing of the valve A is released, that is, the closing signal due to the transition to opening control opens the contact a-4, energizes the solenoid valves MA and MY, and starts mixed cooling. is fully opened, and the drive cylinder supply pressure air is exhausted by the operation of b7 point 2.

In addition, in the case of manual operation, by setting the automatic manual switching circuit ■ to the manual side and operating the two switches 00 for operating the mixed cooling cutoff valve, 111m squares MA and MY are excited, and the rest of the squares are opened. The valve is closed by operating a switch, but in order to avoid one operation during manual and automatic operation, the contact heat-1 is connected to the manual circuit and the line b-1 is connected to the automatic circuit. Cast.

In this experiment, the temperature of the hot air blown with high PK increases by about 20℃, and the reduction power per furnace is approximately 6 x 10 degrees Kca 1.180 x 1 per month.
0'KcaJ! It became a big number 1 ward.

As is clear from the above examples, the method of the present invention
By operating the mixed cooling cut-off valve, which connects the masu to the mixed cooling butterfly valve, we were able to increase the thermal efficiency of the hot blast stove and contribute to the improvement of sparrow energy.

[Brief explanation of the drawing]

Figure 1A1 is a system diagram of a hot air stove, and Figure 2 is a mixed cooling cutoff valve operation circuit diagram of a fire embodiment of the present invention.

Claims (1)

[Claims] (1) In the parallel blowing operation of a hot blast furnace, in which multiple units are provided for one blast furnace and each unit has a mixed cooling butterfly tank for mixing cold air and a mixed cooling cutoff valve, when the mixed cooling butterfly valve is fully closed, A method of operating a hot blast furnace mixed cooling cutoff valve, characterized in that the mixed cooling cutoff valve is fully closed, and the mixed cooling cutoff valve is fully opened when the mixed cooling butterfly box is controlling the opening.