JPH0223489B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for operating a melting furnace for mineral raw materials used in the production of mineral fibers such as rock wool and slag wool. mineral raw materials such as fuel coke are intermittently introduced from above,
When implementing a mineral fiber manufacturing method in which mineral melt is continuously tapped from the lower part of the furnace and directly supplied to the fiberizing process, the amount of combustion air supplied to the melting furnace is adjusted at the time of inputting the mineral raw materials. By rapidly reducing the amount of melted metal, the amount of melted metal supplied to the fiberizing process is stabilized by suppressing the temporary increase in the amount of melted metal.

Conventionally, mineral fibers such as rock wool and slag wool were produced using a cupola-type vertical melting furnace, in which mineral raw materials and fuel coke were intermittently introduced from the top of the furnace, and combustion air was supplied into the furnace at a constant flow rate. The coke is burned to melt the mineral raw material, which is continuously tapped from the bottom of the furnace and collided with the surrounding surface of a high-speed rotating spinner, forming fibers and blowing them in one direction, and then spraying a thermosetting resin adhesive. The adhesive is dried and hardened to a certain thickness while being lightly pressed during the transfer process, and cut into a predetermined size to make a plate-shaped mat product or wound around a mandrel to form a cylindrical shape. Manufactured using a continuous manufacturing process such as turning into products.

In the above continuous manufacturing process, the amount of combustion air blown was always constant during the operation of the melting furnace.
When mineral raw materials are introduced, the ventilation resistance inside the furnace increases, which causes an increase in the pressure inside the furnace, causing a temporary sudden increase in the flow rate of molten metal extruded from the sprue in the lower part of the furnace, and this fluctuation causes fiber formation. There was a problem that the process became unstable.

In particular, fluctuations in the amount of hot water supplied to the fiberization process are
The amount of fiber released from the spinner fluctuates, causing density unevenness in the product. To avoid this, the transfer speed of the cotton collection conveyor is changed in response to spinner load fluctuations, thereby increasing the thickness of the fiber layer deposited on the conveyor surface. However, since the amount of hot water that comes out when mineral raw materials are put into the furnace increases rapidly, it is difficult to increase the conveyor speed accordingly, and it is difficult to increase the conveyor speed accordingly. I couldn't suppress it enough.

The present invention solves the above-mentioned conventional problems, and aims to reduce the amount of melt discharged from the cupola vertical melting furnace.
In order to maintain the combustion air at a substantially constant level even when the mineral raw materials are being input, the amount of combustion air blown is suddenly reduced in connection with the mineral raw material input operation, and after the mineral raw material input is completed, the air blown rate is gradually increased to the specified air flow rate. Thereafter, control is performed to maintain the specified air flow rate until the next time the raw material is added.

The combustion air to the furnace needs to be blown at a specified amount to ensure good combustion of the fuel coke, but if it is 5 to 15% less than the specified air amount, it may be necessary to blow for a short period of time, e.g. 1 to 5 minutes, depending on the extent of the blow. Therefore, in the present invention, the sudden reduction in the air flow rate at the time of raw material input is appropriately determined within the range of 5 to 15% of the specified air flow rate, and the time for maintaining the reduced air flow rate is determined depending on the raw material input. The time is usually about 0.5 to 1.5 minutes, and the time for gradually increasing the amount of air blowing to the specified amount is appropriately determined to be about 2 to 5 minutes.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an explanatory schematic side view of the main parts of the apparatus for manufacturing mineral fiber mat according to the present invention, with only the cupola-type vertical melting furnace in cross section, showing the arrangement of peripheral equipment. It is something.

In the figure, 1 is a cupola-type vertical melting furnace, with a furnace lid 2 at the top of the furnace, a tuyere 3 for blowing combustion air on the lower peripheral wall of the furnace, a sprue 4 slightly above the furnace bottom, and an exhaust passage on the upper wall of the furnace. 5 is provided.

A blower fan 7 is connected to the tuyere 3 via a blower duct 6.
is connected. The blower duct 6 is provided with a furnace pressure measuring device 8 and an orifice 9 for measuring air flow rate, and a differential pressure transmitter 10 is connected to the orifice 9. Also,
A damper 12 is installed in the intake duct 11 of the blower fan 7.
The damper 12 receives the signal from the differential pressure transmitter 10 and the signal from the raw material input signal device 15, and controls the air volume regulator 13 so that a predetermined air flow rate is achieved according to a predetermined air flow rate-time program. is connected, controls the damper actuator 14, and controls the damper 1
The opening degree of No. 2 is adjusted.

20 is a spinner with a horizontal rotation axis provided below the sprue 4; 21 is a constant speed motor that drives the spinner 20 to rotate at high speed; 22 is a current value transmitter for the constant speed motor 21; 23 is a current value transmitter 22 a conveyor speed controller that operates in response to a signal from
24 is a cotton collecting conveyor. Note that 30 is the molten metal flowing down from the sprue, 31 is mineral fiber, and 32 is mineral fiber mat.

The above apparatus is used to produce mineral fiber mat by carrying out the operation method of the melting furnace of the present invention as described below.

When the furnace pressure measuring device 8 detects that the top surface of the mineral raw material in the cupola type vertical melting furnace 1 has decreased as the metal is tapped out and the furnace pressure has decreased to a constant pressure, the furnace lid 2 is opened. , At the same time as a certain amount of coke and mineral raw materials are introduced into the furnace, a raw material input signal 15 is activated.
A signal from the damper actuator 14 is inputted to the air volume controller 13, and the damper actuator 14 is controlled by an air volume-time program as shown in FIG.

That is, at the same time as the raw material is introduced, the damper 12 suddenly operates in the closing direction, the differential pressure detected at the orifice 9 decreases to a certain value, and the air flow becomes a predetermined value below the specified air flow. Damper 12 after being maintained for a short time until the end of raw material input
The damper is gradually opened in the opening direction, and when the specified air flow rate is reached, the damper opening degree is adjusted to maintain that value. During this time, the furnace lid 2 is closed.

The molten metal accumulated at the bottom of the furnace continuously flows out from the sprue 4 according to its level and the internal pressure of the furnace, falls and collides with the circumferential surface of the spinner 20 that is rotating at high speed. The fibers are blown away in 24 directions and fall onto the conveyor surface to form a mineral fiber mat 32.

The molten metal 30 flowing out from the sprue 4 is suppressed from a sudden increase in large amount at the time of inputting the raw material by controlling the air flow rate described above, and is accompanied by the usual slight and gentle fluctuation in the flow rate. Since the current increases or decreases as the load on the high-speed drive motor 21 of the spinner 20 changes, the current value transmitter 22 gives the signal to the conveyor speed controller 23 to increase or decrease the conveyor speed and adjust the thickness of the mineral fiber mat 32. is kept approximately constant.

FIG. 2 is a graph showing a specific example of temporal control of the amount of combustion air blown.

In other words, when manufacturing mineral fiber mat by melting mineral raw materials at a rate of 6 tons per hour using a cupola-type vertical melting furnace with an internal volume of 4 ^m3 , the melting rate is approximately every 12 minutes.
This shows the change in air flow rate when 1.2 tons of blast furnace sludge, silica stone, and 150 kg of coke are put into a melting furnace, and the raw materials are charged at point A and at point B.
The air flow rate is rapidly increased to point D, maintained at that value for about 1 minute until point C, when raw material input ends, and then gradually increased for about 3 minutes to maintain the specified air flow rate at point D. With the next input of raw materials, A′,
This indicates that similar air flow control is performed as in B', C', and D'.

When a mineral fiber mat was manufactured using the above-mentioned method of operating the melting furnace and as explained in Fig. 1, the range of fluctuation of the spinner current was the same as in the conventional method.
This has decreased from 25% to only 3%, and as a result, the range of variation in conveyor speed has decreased from 8% to 3%, and the range of density variation of product mats has decreased by 20%.
The reduction was improved.

As explained above, according to the present invention, it is possible to significantly reduce fluctuations in the continuous output amount of melt in a cupora type vertical melting furnace for producing mineral fibers, and therefore, the method for producing mineral fibers can be carried out in a stable state. Extremely excellent effects can be obtained, such as preventing problems such as breakdowns in manufacturing equipment, reducing operating costs, and improving product quality.

[Brief explanation of drawings]

FIG. 1 is an explanatory schematic side view of the main parts of the apparatus for producing mineral fiber mat according to the present invention, and FIG.
The figure is a graph showing an example of temporal control of the amount of combustion air blown to a cupora type vertical melting furnace. 1... Cupora type vertical melting furnace, 2... Furnace lid, 3... Tuyere, 4... Sprue, 5... Exhaust path, 6... Air duct, 7
...Blower fan, 8...Furnace pressure measuring device, 9...Orifice, 10...Differential pressure transmitter, 11...Intake duct, 12
... damper, 13... air volume regulator, 14... damper actuator, 15... raw material input signal, 20... spinner, 24... conveyor, 30... molten metal, 32... mineral fiber mat.

Claims (1)

[Claims] 1 In a mineral fiber manufacturing method in which mineral raw materials are intermittently introduced from above into a cupora-type vertical melting furnace and the melt is continuously flowed out from below and supplied to the fiberizing process, combustion air is supplied to the melting furnace. At the beginning of mineral raw material input, the air flow rate is suddenly reduced to 5 to 15% of the specified air flow rate, and the reduced air flow rate is maintained until the end of mineral raw material input, and then gradually reduced over a period of 2 to 5 minutes. A method for operating a melting furnace for producing mineral fibers, which comprises increasing the amount of air to a specified amount and thereafter maintaining the specified amount of air.