JPH10263380A - Surface reforming of powder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively use a combustion gas and to decrease the running cost by forcedly sending air heated by a heat exchanger in a high temp. furnace to eject the air through a hot air ejection nozzle into a reaction tank, while ejecting and dispersing a composite material comprising mother particles with deposition of smaller particles in the ejection hot air. SOLUTION: LPG in a gas cylinder 1 is changed into a combustion gas by a vaporizer 2 and combusted by a combustion burner 4. The produced gas is used to heat a heat exchanger 6 in a high temp. furnace 3 and to heat external air passing through the heat exchanger 6 to produce a hot air. The hot air is ejected through a hot air ejection nozzle 14 into a reaction tank 15. A composite material is also supplied to a nozzle header 16 of the reaction tank 15 and is ejected into the flow of the hot air so as to disperse the composite material by collision of the hot air flow and to integrate the mother particles with smaller particles. When the melting point of the mother particles is higher than that of the smaller particles, the surface of the mother particle melts to form a sphere, on which the smaller particles deposit. If the melting point of mother particles is higher than that of the smaller particles, the smaller particles melt and form a film on the surface of the mother particle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for modifying the surface of a powder.

[0002]

2. Description of the Related Art In order to improve various physical properties such as fluidity, dispersibility, and magnetic properties of various powders such as electronic toner, FIG.
As shown in (4), it is known to form a composite A by adhering fine child particles b to the surface of a base particle a serving as a nucleus by triboelectric charging, and then perform a fixing treatment or a film forming treatment.
No. 897, the applicant has already proposed.

In the surface modification method described in the above-mentioned publication, a composite A composed of a base particle a and a child particle b attached to the surface is dispersed and jetted in hot air jetted from a hot air jet nozzle. After instantaneously melting at least one of the child particles b and the surface layer of the base particles a, the cooling is performed.

[0004] In the above-mentioned powder surface reforming method, an electric heater is incorporated in a hot air passage connected to the hot air injection nozzle to supply hot air to the hot air injection nozzle, and the air forcedly fed into the hot air passage is used as the electric heater. A method in which a hot air is formed by heating with a heater, and the hot air is sent to a hot air injection nozzle, and a mixture of liquefied petroleum gas and air is sent to a combustion burner and burned, and the combustion gas is sent to the hot air injection nozzle. The method is known.

[0005]

By the way, in the method of generating hot air using an electric heater, it is possible to easily form a stable and controlled hot air flow. There is a disadvantage that power consumption increases and running costs increase.

On the other hand, the method of generating hot air using liquefied petroleum gas as a fuel is characterized in that running costs are low and a large amount of hot air can be easily formed. In addition, there is an inconvenience that the powders having been subjected to the surface modification treatment tend to adhere to each other or to adhere to each other in a powder transfer path to form a mass. Also,
There is a possibility that the properties (physical properties) of the obtained product may change due to the influence of the generated moisture.

Further, the combustion flame formed by the combustion burner becomes an ignition source, and there is a danger of fire of fine powder or explosion of dust.

An object of the present invention is to provide a method for modifying the surface of powder at a low running cost, capable of continuously and efficiently treating a large amount of a complex.

[0009]

In order to solve the above-mentioned problems, according to the present invention, a mixture of liquefied petroleum gas and air is supplied to a combustion burner provided in a high-temperature kiln, and the mixture is burned. The air is forcibly blown into the heat exchanger heated by the gas, and the hot air formed by the heat exchange is injected into the reaction tank from the hot air injection nozzle, and fine child particles adhere to the surface of the core mother particles. The configuration is adopted in which the composite is diffused and injected into the hot air to melt at least one of the child particles and the surface layer of the base particles, and then cooled by contact with cold air sent into the reaction tank. doing.

[0010] Here, by using the combustion gas heated in the heat exchanger for heating the outside air introduced into the high-temperature kiln, the combustion gas can be effectively used and the running cost can be further reduced.

Further, by controlling the electromagnetic valve provided at the outside air inlet of the high-temperature kiln by the temperature detected by the temperature sensor provided in the hot air passage, the amount of outside air taken in is controlled, thereby injecting hot air at a constant temperature into the hot air. Since it can be supplied to the nozzle, the surface melting treatment of the composite can be stabilized, and a uniform treated product can be obtained.

Further, a valve is attached to the air inlet of the heat exchanger, and the opening of the valve is controlled based on the detected flow rate of a flow meter provided between the heat exchanger and the blower, so that the hot air injection nozzle Since the amount of hot air to be injected can be kept constant, the surface melting treatment of the composite can be stabilized in the same manner as described above, and a uniform treated product can be obtained.

[0013]

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

As shown in FIG. 1, the liquefied petroleum gas LPG filled in the gas cylinder 1 is sent to a vaporizer 2 where it is vaporized to form a fuel gas.

The fuel gas is fed toward a combustion burner 4 provided at the bottom of the high-temperature kiln 3 and mixed with combustion air sent from a first blower 5 before the combustion burner 4. The mixture is sent to the combustion burner 4 and burned.

The combustion gas rises in the high-temperature kiln 3 and heats a heat exchanger 6 provided above the kiln. On the other hand, outside air is blown into the heat exchanger 6 by driving the second blower 7.
The outside air exchanges heat when flowing through the heat exchanger 6, and the hot air formed by the heat exchange flows along the hot air passage 8.

The combustion gas that has heated the heat exchanger 6 flows into the heat exchanger 11. The third blower 10 is connected to the heat exchanger 11, and the outside air is introduced by driving the third blower 10. This outside air is heated by the exhaust heat of the combustion gas passing through the heat exchanger 11 and is introduced into the high-temperature kiln 3. As described above, in order to uniformly heat the wide heat exchanger 6, an indirect heating method using a large amount of high-temperature gas is excellent.

The air inlet 10a of the third blower 10
It is opened and closed by the first valve V _1. First valve V ₁
Opening is PI control based on the first temperature detected temperature of the sensor T ₁ provided in the hot air passage 8.

That is, when the temperature of the hot air flowing through the hot air passage 8 is higher than a preset temperature, the opening of the first valve V ₁ increases, and the opening decreases as the temperature of the hot air decreases. Is controlled so that

The above control of the first valve V ₁ controls the flow rate of the combustion gas flowing into the high-temperature kiln 3 from the air inlet 10a, and the temperature of the hot air exchanged by the heat exchanger 6 becomes a predetermined temperature. Will be managed.

A second valve V ₂ is attached to the air inlet 12 of the second blower 7, and the second valve is based on a detected flow rate of a flow meter 13 provided between the second blower 7 and the heat exchanger 6. The opening degree is controlled by PI.

That is, the second valve V ₂ is connected to the hot air passage 8
When the amount of hot air flowing through the hot air is larger than a preset flow rate, the opening is reduced, and the opening is controlled to increase as the amount of hot air decreases. Therefore, the amount of hot air is always sent to the hot air passage 8 by a fixed amount.

The hot air flowing through the hot air passage 8 is injected downward into the reaction tank 15 from a hot air injection nozzle 14 shown in FIG.

The reaction tank 15 has a tapered shape having a small diameter at a lower portion, and an annular nozzle header 16 having a hot air injection nozzle 14 as an axis is provided at an upper portion thereof.

The nozzle header 16 has an annular passage 17,
The lower portion of the inner diameter surface is formed as a tapered surface 18.
Are provided with a plurality of composite injection nozzles 19 at equal intervals.

The composite A shown in FIG. 3I is supplied to the annular passage 17 of the nozzle header 16. Here, as shown in FIG.
6, an air supply pipe 20 is connected to the air supply pipe 20, an outlet of the hopper 21 is connected to the air supply pipe 20, and the composite air supplied into the hopper 21 by the ejector action of the compressed air supplied to the air supply pipe 20 is connected. The body A is sent into the annular passage 17 shown in FIG.

The composite A supplied to the annular passage 17 turns in the annular passage 17 and is jetted from each of the composite jet nozzles 19. At this time, the composite A is injected toward the hot air stream jetted from the hot air jet nozzle 19, is dispersed by the collision of the hot air stream, is heated, and the mother particles a and the child particles b are integrated. You. In this case, when the melting point of the base particles a is lower than the melting point of the child particles b, the surface layer portion of the base particles a melts and becomes spherical, and the child particles b adhere to the surface. It melts to form a film on the surface of the base particles a.

During the heat treatment of the composite A, the hot air jet nozzle 1
The hot air injected from 4 is managed so that the temperature and the air volume are constant, and the composite A is dispersed and supplied to the hot air, so that a large number of the composites A are heated substantially uniformly. For this reason, a uniform heat-treated product having a constant quality is formed.

The temperature and air volume of the hot air are based on the base particles a
Alternatively, it is appropriately set according to the material of the child particles b.

The heat-treated composite A ′ is supplied to the reaction tank 15.
To move down. Cool air is supplied to the upper part in the reaction tank 15.

As the cool air supply device 22, here, a fourth end of a cool air passage 24 connected to a cool air injection nozzle 23 is provided.
A blower 25 is connected, a heat exchanger 26 is connected to the discharge side of the fourth blower 25, a part of a cooling water pipe 27 is inserted into the heat exchanger 26, and the cooling air is driven by the fourth blower 25. When the outside air sent into the passage 24 flows in the heat exchanger 26, cold air cooled by contact with the cooling water pipe 27 is injected into the reaction tank 15 from the cooling nozzle 23.

The cool air blown from the cool air spray nozzle 23 is sprayed in a direction tangential to the outer periphery in the reaction tank 15. For this reason, the cool air is swirled in the reaction tank 15, and the complex A 'after the heat treatment is rapidly cooled by contact with the swirled cool air.

Here, a fourth electromagnetic valve V ₄ is connected to the outside air intake 28 of the fourth blower 25. 4th
The opening of the electromagnetic valve V ₄ is controlled based on the flow rate detected by a flow meter 29 provided between the blower 25 and the heat exchanger 26, and the flow rate of the cool air injected from the cool air injection nozzle 23 is set at a preset flow rate. Will be managed.

Therefore, the complex A ′ after the heat treatment is effectively cooled, and the complex A ′ after the cooling treatment is cooled in the reaction tank 15.
The product is sucked and conveyed to the cyclone separator 30 from the lower outlet of the cyclone separator 30 to be separated into a product and a gas.
From the lower exit of On the other hand, the gas is suctioned and conveyed to a bag filter (not shown), and the powder contained in the gas is collected.

If the cooling of the complex A 'is incomplete, the complex A' may be removed from the reaction tank 15, the transport passage 31 connecting the reaction tank 15 and the cyclone separator 30, or the inside of the cyclone separator 30. Because it may adhere to the circumference,
It is necessary to control the temperature and the flow rate of the cool air to the optimum temperature for cooling the composite A '.

[0036]

The present invention is configured as described above.
The following effects are obtained.

According to the first aspect of the present invention, liquefied petroleum gas is used as fuel, and the heat exchanger is heated by the combustion gas of the liquefied petroleum gas to raise the temperature of the air sent into the heat exchanger. In addition, a large amount of dry hot air with low moisture can be formed. Since the composite is heated and melted by contact with this dry hot air, the composite is melted without containing moisture, and there is no inconvenience that the composite after cooling adheres to the passage, and a large amount of the composite is produced. Can be continuously and efficiently processed. Further, there is no possibility of dust explosion, and the treatment can be performed safely.

According to the second aspect of the present invention, the combustion gas heated in the heat exchanger is reused for heating the outside air flowing into the high-temperature kiln, so that the combustion gas is not wasted and the running cost is reduced. Can be planned.

According to the third aspect of the invention, since the temperature of the hot air can be controlled to a predetermined temperature, a uniform product of uniform quality can be obtained without uneven heating of the composite.

In the invention according to claim 4, since the flow rate of the hot air can be controlled to a predetermined flow rate, a uniform product can be obtained as described above.

According to the fifth aspect of the present invention, it is possible to easily form a large amount of cold air and to control the temperature of the cold air at a predetermined temperature in order to circulate air in the heat exchanger through which the cooling pipe is inserted. Therefore, the heat-melted composite can be uniformly cooled throughout, and a product of excellent quality can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a surface modification apparatus used in a method according to the present invention.

FIG. 2 is a cross-sectional view showing details of a hot-air jet unit according to the first embodiment;

FIG. 3 (I) is a cross-sectional view of the composite, and (II) is a cross-sectional view showing the composite after heat treatment.

[Explanation of symbols]

a mother particle b child particle 3 high temperature kiln 4 combustion burner 6 heat exchanger 8 hot air passage 10 blower 10a outside air intake 11 heat exchanger 13 flow meter 14 hot air injection nozzle 23 cold air injection nozzle 24 cold air passage 25 fourth blower 26 heat exchange vessel 27 coolant pipe 29 flow meter V ₁ first valve V ₂ second valve V ₄ 4th valve T ₁ first temperature sensor

Claims (5)

[Claims] An air-fuel mixture of liquefied petroleum gas and air is supplied to a combustion burner provided inside a high-temperature kiln and burned, and air is forcibly blown into a heat exchanger heated by the combustion gas to exchange heat. The hot air formed by the hot air injection nozzle is injected into the reaction tank from the hot air injection nozzle, and a composite in which fine child particles are adhered to the surface of the core particles serving as the nucleus is diffused and injected into the above-described hot air to be injected, and A method for modifying the surface of a powder, characterized in that at least one of the surface layer portions of the base particles is instantaneously melted and then cooled by contact with cold air sent into the reaction tank. 2. The method for modifying the surface of a powder according to claim 1, wherein the outside air introduced into the high-temperature kiln is heated by the heat-exchanged combustion gas that has heated the heat exchanger. 3. The temperature of hot air supplied to the reaction tank by controlling the opening of a valve for opening and closing the outside air intake of the outside air introduced into the high temperature kiln based on the temperature detected by a temperature sensor provided in a hot air passage. The surface modification method according to claim 2, wherein the temperature is controlled to a set temperature. 4. A valve is connected to the air inlet of the heat exchanger, and the degree of opening of the valve is controlled based on the detected flow rate of a flow meter provided between the heat exchanger and the blower and supplied to the reaction tank. 4. The method for modifying the surface of powder according to claim 1, wherein the amount of hot air is controlled to a set amount. 5. A supply means for supplying cold air to the reaction tank,
A cool air passage is connected to a cool air injection nozzle connected to the reaction tank, a blower is connected to an end of the cool air passage, and a heat exchanger having a cooling water pipe inserted on the discharge side of the blower is provided, and the blower is provided. The surface of the powder according to any one of claims 1 to 4, wherein when the outside air sent into the cold air passage by the drive of the fluid flows in the heat exchanger, the outside air is cooled by contact with a cooling water pipe. Reforming method.