JP3028474B2 - Method and apparatus for producing fine hollow glass spheres - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic ball medium internal combustion type fluidized bed furnace type fine-grained hollow glass sphere which is heat-treated by mixing powder of raw material for a fine-grained hollow glass sphere with a mixed gas of air and fuel gas. A method and apparatus for producing a body.

[0002]

2. Description of the Related Art Japanese Patent No. 848394 discloses a method for starting and controlling the temperature of an internal combustion type fluidized bed furnace used as an apparatus for producing a shirasu balloon or the like.
In this method, a mixed gas of air and a fuel gas is blown into a sand medium (brick powder) heated in advance to the flash point of the used fuel to form a high-temperature fluid state and maintain the temperature. This temperature is maintained by controlling the fuel gas by a motor-operated valve by a controller connected to a thermocouple, and is at a set temperature of about ± 5 ° C.

[0003]

In THE INVENTION Problems to be Solved by the internal combustion fluidized bed furnace of the prior art, a flash point below the state of the temperature of the fuel gas sand medium, when a mixed gas of the same air-fuel ratio at a high temperature fluidized sand The gas mixture will misfire because the medium does not serve as an ignition source. As a countermeasure against the misfiring, it was necessary to heat the sand medium to a temperature higher than the flash point with an attached preheating device before introducing a mixed gas of air and fuel gas. Therefore, as shown in Hokkaido Industrial Development Laboratory Report 42, (1987), it was necessary to open a side hole near the center of the flowing part and heat it vigorously. Since this preheating burner is not used at the time of high-temperature fluidization, the backflow of sand occurs, and the amount of sand to be fluidized changes with time.
In addition, there is a disadvantage that a portion having a low temperature of 10 ° C. or more is generated in the fluidized bed due to heat loss near the attachment port of the preheating burner during the flow, and the heating of the object to be heated becomes uneven. Also,
Although brick powder and silica sand in sand media are used, it is so well fracturing during flow, the debris fine hollow moth
There is a drawback of mixing in lath spheroid products (for example, shirasu balloon). Further, regarding temperature maintenance, since only the fuel gas is fully opened and fully closed using an electrically operated valve having relatively slow controllability, the fluctuation of the optimum combustion air-fuel ratio becomes a disturbance factor, and the set temperature becomes about ± 5 ° C. Poor temperature controllability.

[0004]

In order to solve the above-mentioned problems, a fluidized bed furnace using a ceramic ball as a medium without using a preheating burner has been developed. After careful examination , we came to the invention with the following structure.
Was. (1) Ceramic boa as a medium in an internal combustion type fluidized bed furnace
Of fuel gas and air on the ceramic ball
The mixed gas is supplied, and the ceramics
Temperature to 900 ° C or higher,
Of raw material powder for fine hollow glass spheres
Is supplied along with the mixed gas to form fine hollow glass.
Fine-grained hollow glass sphere characterized by producing spherical body
How to make the body . (2) Production of the fine hollow glass spheres according to the above (1)
Method, without using the attached preheating burner,
Air flow controller and fuel gas flow controller
The ceramic is controlled by the double cross limit control that gives a constant value.
Grass ball is gradually heated by the heat of gas combustion to fluidize it at high temperature.
Immediately before, the PID output of the fluidized bed temperature controller was forcibly reduced.
Sudden temperature by switching to direct control
Mixing air and fuel gas after preventing rise and fluidizing at high temperature
Adjust the total gas volume to the volume preset for high temperature fluidization.
Performed pollock Ru variable air-fuel ratio control, further fluidized bed temperature controller
Variable PID control to change the PID setting of
By performing this together with the double cross limit control,
And the ceramic body below the flash point of the mixed gas
Temperature to 900 ° C or more with gas combustion heat,
In fine particles characterized by automatic temperature control within 3 ° C
A method for producing an empty glass sphere. (3) Having ceramic balls as a fluidized bed medium
An internal combustion type fluidized bed furnace and the same ceramic balls with fuel gas
Mixed gas supply means for supplying a mixed gas with air
And heat the ceramic balls by 900 ° C or less
Temperature that rises to the top and performs temperature control within the set temperature ± 3 ° C
Degree control means and simultaneously with said temperature control, fine hollow glass spheres
To supply the raw material powder in the form of a solid with the mixed gas
Characterized by being provided with a powder supply means.
Equipment for manufacturing empty glass spheres. (4) Production of the fine hollow glass spheres according to the above (3)
When the temperature rises, the air flow controller and the fuel gas flow
Double cross limit to provide the controller with appropriate flow settings
Control means and the ceramic balls gradually with the heat of gas combustion
Immediately before fluidization at a high temperature.
Direct control means for forcibly reducing the D output;
The total gas mixture of gas and fuel gas is used for high-temperature fluidization in advance.
Variable air-fuel ratio control means for adjusting to the amount set in
Variable PI to change the PID setting of the floor temperature controller from when the temperature is raised
D control means and double cross limit
Control means for controlling the temperature below the flash point of the mixed gas.
Ramix ball heated to 900 ° C or more by gas combustion heat
And perform automatic temperature control within the set temperature ± 3 ° C.
An apparatus for producing fine hollow glass spheres.

[0005] The inventors of the present invention have made ceramic media as described above.
Developed a fluidized-bed furnace using hot-ball
A close examination of the optimal combustion conditions during operation revealed that the optimal combustion conditions differed between when the temperature was raised and when the fluid flowed at a high temperature, and that there was a high risk of a sudden rise in temperature immediately before the fluidization at a high temperature. Therefore, as a result of repeating experiments on these solutions , ceramic balls were used for the fluidized bed furnace medium.
In addition, by setting the optimum output of the temperature controller by variable air-fuel ratio control, direct control, variable PID control and double cross limit combustion control that precisely corresponds to the combustion conditions, automatic startup can be performed safely and in a short time. It found that can be achieved, also fine high-precision temperature control during hot flow
We succeeded in developing a method and an apparatus for producing a hollow glass sphere .

[0006] The difference between the latent heat and the radiant heat of the medium (ceramic ball) between the time of temperature rise and the time of high-temperature flow is the optimum combustion P.
Since the ID control condition and the air-fuel ratio are different, the control condition must be changed. If the change is neglected, the fusion of the medium or flashback occurs due to a rapid rise in the furnace temperature, and a dangerous state occurs, and the fluidized-bed furnace is consumed and damaged, resulting in loss of control. Therefore, at the temperature lower by 50 ° C. from the set temperature, the PID control condition is automatically changed and the variable air-fuel ratio control is switched, and the rate of change of the temperature is recognized. By programming the circuit for setting the output in advance, it has become possible to avoid a sudden rise in temperature, and to achieve a safe and quick high-temperature fluidization.

If the air-fuel ratio is made constant during high-temperature flow, the amount of air fluctuates in accordance with the fuel gas flow rate that fluctuates with the control output of the temperature controller, so that the amount of combustion gas passing through the fluidized bed fluctuates. In this case, the object to be heated ( fine-grained hollow glass sphere
Heat history of the raw material powder) is fluctuated and the quality of fine hollow particles
Since a spherical product was not obtained, variable air-fuel ratio control was performed in which the air-fuel ratio was varied to control the fuel gas flow rate in order to keep the amount of combustion gas substantially constant. Important to this temperature control is accurate control and measurement of the fuel gas flow rate and the air flow rate.
For this purpose, air-operated control valves (for fuel gas and air) that can control the flow rate with high precision were used. Further, in order to improve the accuracy, a self-acting pressure reducing valve (for fuel gas and for air) for stabilizing the supply pressure is employed. A high-precision digital gas flow meter was used for flow measurement. As a safety measure, a system is adopted that shuts off the fuel gas in the event of an abnormality in the temperature under the furnace, air pressure, inverter and control temperature.

Further, since the apparatus of the present invention does not include a preheating burner, the fluidized bed portion has a completely cylindrical shape and has a structure suitable for uniform temperature distribution. By combining these devices and structures with high-performance temperature controllers, fuel gas controllers, air flow controllers, and air-fuel ratio setting devices, highly accurate temperature control has become possible. By automating the above operations, a stable high-temperature fluidized state was successfully formed in a short time. Furthermore, in order to prevent mixing of the medium fragments into the product, silicon carbide balls and cordierite balls having excellent thermal shock resistance were used as the medium. Thereby, the crushing of the medium during the high temperature fluidization was almost eliminated, and the production of a high quality product became possible. Used in the present invention
Raw materials for inorganic foaming materials include vitreous volcaniclastics and gas.
There is natural glass such as lath volcanic rock and has foam source
Artificial glass can also be foamed.

[0009]

EXAMPLE A ceramic ball (silicon carbide) having a diameter of 1.5 mm was placed on a fluidized bed portion having an inner cylinder having an inner diameter of 132 mm.
Are charged at 1750 g. After introducing a mixed gas of propane gas and air into the fluidized bed and igniting, the PID is maintained at a constant air-fuel ratio.
Under control, the temperature of the ceramic balls is raised by the heat of combustion. Then, when the temperature of the ceramic ball is lowered by 50 ° C. (950 ° C.) from the set temperature (1000 ° C.), the PID
As the control conditions were changed, the air conditioner was switched to variable air-fuel ratio control and stabilized at a set temperature of 1000 ° C. ± 3 ° C. or less. The time required from ignition to stabilization at the set temperature was 12 minutes. As the powder of the material to be heated, fine shirasu powder having an average particle diameter of 4 μm (produced by Yoshida-cho, Kagoshima Prefecture) was supplied to the fluidized bed at 1.0 kg / h in association with the mixed gas before combustion. To produce a fine and lightweight shirasu balloon having an average particle size of 6.2 μm and a bulk specific gravity of 0.3. Even when supplying fine Shirasu powder, variable PI
The D temperature control and the variable air-fuel ratio control maintained the temperature at or below the set temperature ± 3 ° C., and a high-quality shirasu balloon free of impurities could be manufactured.

[0010]

According to the present invention, fine particles such as shirasu balloons can be used.
Granular hollow glass spheroidal products, conventional brick powder and silica sand
Debris and impurities child contamination case of sand Courier equal
And almost no. In addition, the furnace temperature as in the conventional method
There is no fusion of the medium due to the sudden rise,
The risk of damage or loss of control can be avoided. Furthermore, high-temperature fluidization can be automatically performed in a short time, and fluidized-bed temperature control can be performed with high precision. As a result, high-quality products can be manufactured with automation and labor saving.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an internal combustion type fluidized bed furnace using ceramic balls as a medium.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshitaka Kamino 1445-1, Oda, Hayato-cho, Aira-gun, Kagoshima Prefecture Inside the Kagoshima Industrial Technology Center (72) Kazuto Hamaishi 1445-1, Oda, Hayato-cho, Aira-gun, Kagoshima Kagoshima Prefectural Industrial Technology Center (72) Inventor Keinori Yoshimura 1049 Kawahara Iwasaka, Kokubu-shi, Kagoshima Prefecture (72) Inventor Shunji Tone 2--15-12 Katano, Kokurakita-ku, Kitakyushu City Examiner Hideo Tokunaga (56) References Special JP-A-6-2811 (JP, A) JP-A-7-315869 (JP, A) JP-A-50-47880 (JP, A) JP-A-61-96115 (JP, U) JP-B-51-22922 ( JP, B2) JP-B 61-6289 (JP, B2) JP-B 63-65842 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) C03B 19/08 C03B 19/10 F23C 10/18

Claims (4)

(57) [Claims] A ceramic ball is used as a medium in an internal combustion type fluidized bed furnace .
Supplying a mixed gas of air, ceramic in the gas combustion heat
The temperature was raised to 900 ° C. or higher Suboru original temperature control line Utodojini fine hollow glass within a set temperature ± 3 ° C.
The powder mixture is supplied along with the mixed gas to provide fine hollow particles.
A method for producing a fine hollow glass sphere, comprising producing a glass sphere. 2. The method for producing a fine hollow glass sphere according to claim 1 , wherein the temperature is raised without using an attached preheating burner.
Sometimes an appropriate flow rate for air flow controllers and fuel gas flow controllers
The ceramic ball is gradually heated by the heat of gas combustion by the double cross limit control to give the set value,
Pressure of PID of fluidized bed temperature controller immediately before
Sudden temperature by switching to direct control
Temperature rise and fluidized at high temperature, then mix air and fuel gas.
Combined gas volume to the amount set in advance for high-temperature fluidization
Performs variable air-fuel ratio control for adjusting further fluidized bed temperature controller
Before variable PID control, which changes the PID setting of the gauge to that at the time of temperature rise
This can be performed in conjunction with the double cross limit control.
The temperature of the ceramic balls having a flash point less than the flash point of the mixed gas is raised to 900 ° C. or more by the heat of gas combustion, and the temperature is set at ± 10 ° C.
A method for producing a fine-grained hollow glass sphere, characterized by performing automatic temperature control within 3 ° C. 3. A ceramic ball as a fluidized bed medium.
With an internal combustion type fluidized bed furnace and fuel on the ceramic balls
Mixed gas supply for supplying a mixed gas of gas and air
Means and a ceramic ball 900
Temperature rise to over ℃, and temperature control is performed within ± 3 ℃ of set temperature.
Temperature control means;
Spherical raw material powder is supplied along with the mixed gas.
And a raw material powder supply means . 4. A method for producing a fine hollow glass sphere according to claim 3.
Air flow meter and fuel gas flow
Double cross limit that gives the flow controller an appropriate flow setting
And Tsu DOO control means, Xu ceramic balls in the gas combustion heat
The temperature of the fluidized bed temperature controller is increased immediately before fluidization at high temperature.
Direct control means for forcibly reducing ID output;
High-temperature fluidization of the total gas mixture of air and fuel gas in advance
Variable air-fuel ratio control means for adjusting to the amount set for
Variable P that changes the PID setting of the moving bed temperature controller to that when the temperature rises
ID control means and double cross limit at high temperature flow
Comprising a Tsu DOO control means, the ceramic balls is less than the flash point of the mixed gas was raised to above 900 ° C. In the gas combustion heat, so as to perform automatic temperature control within a set temperature ± 3 ° C.
An apparatus for producing a fine hollow glass sphere.