JP5068720B2 - Spherical particle production equipment - Google Patents

Description

  The present invention relates to a spherical particle manufacturing apparatus that melts raw material particles with a flame.

  An apparatus for obtaining spherical particles by melting an inorganic powder as a raw material through a flame is known. For example, in order to melt lime-based inorganic powder, a flame of 1200 ° C. or higher is required, and the conventional spherical particle manufacturing apparatus has a furnace body made of a refractory material such as brick.

  In the spherical particle manufacturing apparatus described in Patent Documents 1 and 2, cooling air is injected along the inner wall of the furnace body, the inner wall is cooled to 800 ° C. or less, and the molten raw material adheres to the inner wall (clinker). Is suppressed.

  If the maximum temperature of the furnace body is 800 ° C. or less, it is possible to reduce the cost by making the furnace body made of metal such as SUS316L. However, since it is not easy to supply sufficient cooling air to the entire inner wall of the furnace body, and the furnace body is likely to be locally hot, the spherical particle production apparatus described in Patent Documents 1 and 2 It is dangerous to make the furnace body of a metal body.

  Further, in order to increase the processing capacity of the spherical particle manufacturing apparatus, it is necessary to enlarge the furnace body in order to secure a flame space. In that case, in order to cool the inner wall of the furnace body, it is necessary to introduce a large amount of cooling air, and the amount of exhaust gas increases, so there are large facilities such as a dust collector and a processing tower for treating the exhaust gas. Necessary and costly.

  Further, such a spherical particle manufacturing apparatus is also required to improve thermal efficiency by collecting exhaust heat. In the spherical particle manufacturing apparatus, the temperature of the combustion exhaust gas cooled to below the melting point of the particles is further reduced to the heat resistance temperature of the spherical particle recovery apparatus such as a bag filter (for example, about 250 ° C. for bag filters coated with Teflon (registered trademark)). Dilution air is introduced to make the following. For this reason, effective heat recovery is no longer possible from the exhaust gas after separating the spherical particles.

In addition, since a convection heat exchanger such as a multi-tube type or a plate type is used to recover heat from combustion exhaust gas containing spherical particles, there is a high risk of occurrence of problems such as clogging and wear. Even when a radiant heat exchanger is used, there is a problem that sufficient heat recovery cannot be performed or the apparatus becomes large. In addition, it is necessary to periodically remove particles adhering to the heat exchanger, and there is a problem that maintenance costs are increased.
Japanese Patent Laid-Open No. 11-337042 JP 2002-166161 A

  In view of the above problems, it is an object of the present invention to provide a spherical particle manufacturing apparatus that can easily recover exhaust heat and can suppress equipment costs.

In order to solve the above-mentioned problem, a spherical particle manufacturing apparatus according to the present invention includes a metal inner cylinder, an outer cylinder surrounding the inner cylinder, and a flame combustion apparatus disposed on the upper part of the inner cylinder. The cooling air is inserted into the gap between the inner cylinder and the outer cylinder, and the cooling air that has passed through the gap between the inner cylinder and the outer cylinder is used as the combustion air of the flame combustion apparatus .

  According to this structure, by making the furnace body into a jacket structure, the cooling air can be supplied and cooled throughout the entire outer surface of the metal inner cylinder, so that the furnace body can be kept below the service temperature. Since the furnace body is made of metal, the cost can be reduced and the installation space can be reduced. Further, since the cooling air is separated from the combustion gas, heat energy can be recovered by exchanging heat through the inner cylinder and reusing the cooling air that has reached a high temperature. Further, since cooling air is not introduced into the combustion gas, the amount of exhaust gas does not increase, and the capacity of powder recovery equipment (such as a cyclone separator or bag filter) and exhaust gas treatment equipment can be reduced.

Further , according to this configuration, since heat is exchanged between the high-temperature combustion gas and the cooling air, the temperature of the cooling air becomes high. The temperature of the flame can be increased by reusing the high-temperature cooling air as combustion air. Thereby, the spheroidization rate of particles can be increased without consuming excess energy (fuel).

  Further, in the spherical particle manufacturing apparatus of the present invention, a part of the cooling air that has passed through the gap between the inner cylinder and the outer cylinder is discharged to the outside, and the amount of air supplied to the flame combustion apparatus is adjusted. You may have an air quantity adjustment means.

  According to this configuration, since the air-fuel ratio can be optimally maintained by adjusting the amount of combustion air while maintaining the optimal flow rate of cooling air for cooling the inner cylinder, high combustion efficiency can be obtained.

  Moreover, the spherical particle manufacturing apparatus of this invention may have a partition plate which divides | segments the clearance gap between the said inner cylinder and the said outer cylinder helically.

  According to this configuration, the flow path of the cooling air can be narrowed to increase the flow velocity, and thereby the inner cylinder can be sufficiently cooled.

  Moreover, the spherical particle manufacturing apparatus of this invention WHEREIN: The said inner cylinder or the said outer cylinder may have an expansion-contraction member which can be expanded-contracted in the vertical direction.

  According to this structure, the difference in the expansion coefficient due to the temperature difference between the inner cylinder and the outer cylinder can be absorbed.

  In the spherical particle manufacturing apparatus of the present invention, the cooling air may be supplied via an annular buffer chamber that communicates with the inner cylinder, the outer cylinder, the gap, and the entire circumference.

  According to this configuration, the flow of the cooling air cannot be biased, and the inner cylinder can be uniformly cooled in the circumferential direction.

  In the spherical particle manufacturing apparatus of the present invention, the cooling air may be supplied to the upper part of the gap between the inner cylinder and the outer cylinder and discharged from the lower part.

  According to this configuration, cooling air having a low temperature can be supplied from the upper part where a large amount of heat is transferred to the inner cylinder close to the flame, so that efficient heat exchange is possible and the maximum temperature of the inner cylinder is lowered. And the flow rate of cooling air can be reduced.

  As described above, according to the present invention, it is possible to keep the furnace body below the service temperature by providing the furnace body with a metal jacket structure and providing a heat exchange mechanism. In addition, since the cooling air is separated from the combustion gas and is not introduced into the furnace body, the amount of exhaust gas can be reduced and efficient heat recovery can be achieved by secondary use of the cooling air.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In FIG. 1, the spherical particle manufacturing apparatus 1 of one Embodiment of this invention is shown. The spherical particle manufacturing apparatus 1 has a substantially cylindrical furnace body 3 in which a flame combustion apparatus 2 is disposed at the upper end and the lower end is reduced in diameter.

  The furnace body 3 includes an upper body 5 that forms a melting chamber 4 that contains the flame of the flame combustion apparatus 2, and a lower body 7 that forms a cooling chamber 6 that communicates with the melting chamber 4. The upper main body 5 has, for example, a jacket structure made of a double pipe of an inner cylinder 8 made of SUS316L and an outer cylinder 9 made of SUS304L that surrounds the inner cylinder 8, with an inner diameter of 1100 mm, an effective height of 1800 mm. For example, the gap between the inner cylinder 8 and the outer cylinder 9 is 18 mm, and the inner cylinder 8 or the outer cylinder 9 has two strip-shaped partitions that spirally divide the gap between the inner cylinder 8 and the outer cylinder 9. A plate 10 is provided.

  Further, the upper body 5 has an upper end that is reduced in the shape of an umbrella in accordance with the diameter of the flame combustion apparatus 2, and an upper end of the inner cylinder 8 that is formed in a bellows shape so as to surround the flame combustion apparatus 2. A flexible bellows (expandable member) 11 is provided. The bellows 11 absorbs the difference in thermal expansion due to the temperature difference between the inner cylinder 8 and the outer cylinder 9. Here, the bellows 11 is arranged around the flame combustion device 2 so that the diameter is small and is not directly exposed to the flame. In the present embodiment, a shielding plate 12 is further arranged inside the bellows 11 to block radiant heat from the flame, prevent powder from entering the bellows 11, and protect it so that its expansion and contraction function is not impaired. Yes. Further, a partition wall 13 extending upward to surround the bellows 11 is provided at the reduced diameter upper end of the outer cylinder 9.

  The upper body 5 is disposed so as to surround the reduced diameter portion at the upper end of the outer cylinder 9, and extends over the entire circumference via the upper end of the gap between the inner cylinder 8 and the outer cylinder 9 and the gap between the bellows 11 and the partition wall 13. An annular intake buffer chamber 14 that communicates with each other is provided. The intake buffer chamber 14 is provided with an intake pipe 17 for introducing cooling air for cooling the upper main body 5, in particular, the inner cylinder 8, from the blower 15 through the adjustment valve 16. The opening of the adjustment valve 16 is adjusted based on the inner cylinder 8 detected by the temperature detector 18 so that the temperature of the inner cylinder 8 becomes the set temperature.

  The upper body 5 further includes an annular exhaust buffer chamber 19 that further surrounds the lower end portion of the outer cylinder 9 and communicates with the lower end of the gap between the inner cylinder 8 and the outer cylinder 9 over the entire circumference. The exhaust buffer chamber 19 has an exhaust pipe 20 for exhausting the cooling air inserted through the gap between the inner cylinder 8 and the outer cylinder 9.

  The lower body 7 has a water cooling jacket 21 through which cooling water is inserted on the outer periphery, and the manufactured spherical particles are mixed with carrier air at the lower end to form a powder recovery device (not shown) such as a bag filter. A transport pipe 22 is provided for transport.

  The flame combustion device 2 has a substantially triple tubular structure, is supplied with raw material inorganic powder, fuel gas, and combustion air, forms a flame vertically downward in the melting chamber 4, and has a high temperature. Inorganic powder can be heated in a flame. The spherical particle manufacturing apparatus 1 heats and melts the inorganic powder by supplying it into the flame in the melting chamber 4, and cools it below the melting point together with the combustion gas in the cooling chamber 6. A powder spheroidized by tension is obtained.

  As the combustion air supplied to the flame combustion apparatus 2, the cooling air that has passed through the gap between the inner cylinder 8 and the outer cylinder 9 is reused. The cooling air needs to ensure a constant flow rate in order to keep the inner cylinder 8 below the service temperature. On the other hand, the flow rate of combustion air is determined from the optimum air-fuel ratio corresponding to the flow rate of fuel gas. In this embodiment, the required flow rate of combustion air is smaller than the lower limit flow rate of cooling air. For this reason, excess air is discharged to the outside through the bleed valve 23. Specifically, the mass flow rate of the air supplied to the flame combustion apparatus 2 is detected by the flow rate detector 24, for example, by calculating from the differential pressure before and after passing through the orifice and the air temperature. Based on the detected value, the opening of the bleed valve 23 is adjusted, for example, PID controlled (combustion air amount) so that the flow rate becomes a value calculated from the optimum air-fuel ratio according to the flow rate of the fuel gas. Adjusting means).

For example, when the flame temperature is required to be about 1200 ° C. for melting the inorganic powder, LPG (calorific value: 21800 kcal / m ³ N) is required as the fuel gas, and 12 m ³ N / h is required for the combustion. The working air is 287 m ³ N / h.

Further, in the present embodiment, for example, in order to maintain the inner cylinder 8 below the service temperature under normal conditions from the blower 15 through the intake pipe 17, the cooling for 390 m ³ N / h is performed as follows. Designed to be supplied with air. The intake buffer chamber 14 temporarily reduces the flow rate of the supplied cooling air, and supplies the cooling air to the entire upper end of the gap between the inner cylinder 8 and the outer cylinder 9 at a substantially uniform flow rate. Thereby, the cooling air can be inserted evenly in the circumferential direction along the outer surface of the inner cylinder 8.

  In the present embodiment, the presence of the partition wall 13 forms a cooling air passage along the outer periphery of the bellows 11. Thereby, the cooling air is inserted from the intake buffer chamber 14 to the periphery of the bellows 11 at a uniform and sufficient flow velocity, and the bellows 11 can be cooled.

  Furthermore, in this embodiment, since the partition plate 10 is provided in a spiral shape in the gap between the inner cylinder 8 and the outer cylinder 9, the cooling air flows evenly on the outer side of the inner cylinder 8, and the flow velocity of the cooling air Can be high. By increasing the flow rate of the cooling air, heat exchange between the inner cylinder 8 and the cooling air can be promoted.

In this embodiment, the speed of the cooling air in the gap between the inner cylinder 8 and the outer cylinder 9 divided by the partition plate 10 is about 8.9 m / sec when the average temperature of the cooling air is 200 ° C. . At this flow rate of 8.9 m / sec, the heat transfer rate per unit area between the combustion gas of the flame combustion apparatus 2 and the cooling air via the inner cylinder 8 is calculated according to the heat transfer model of the cylindrical wall. About 32.8 kcal / m ² · h · ° C.

  FIG. 2 shows changes in the combustion gas temperature in the melting chamber 4, the inner surface temperature of the inner cylinder 8, and the cooling air temperature in the gap between the inner cylinder 8 and the outer cylinder 9 depending on the height of the upper body 5. . As shown in the figure, under this condition, the maximum temperature of the inner cylinder 8 is about 650 ° C., and is a temperature that can sufficiently withstand the structure even in consideration of the safety factor and the like.

  In the present embodiment, the combustion air and the cooling air are supplied from the same side by supplying the cooling air to the upper end of the gap between the inner cylinder 8 and the outer cylinder 9 and exhausting it from the lower end. Therefore, the maximum temperature of the inner cylinder 8 is lowered by lowering the temperature of the combustion gas earlier.

  As described above, since the furnace body 3 of the spherical powder manufacturing apparatus 1 of the present invention can be composed entirely of metal, it can be installed at a lower cost than using a refractory, and maintenance is easy.

  Further, as shown in FIG. 2, the temperature of the cooling air exhausted from the exhaust pipe 20 is about 430 ° C., and it is sufficiently reused as the combustion air of the flame combustion apparatus 2 to sufficiently save energy. Can contribute. That is, in the present invention, the cooling air exchanges heat with the high-temperature combustion gas via the inner wall 8, so that efficient heat recovery is possible. This is a great advantage in that it is unnecessary to install and maintain a heat exchanger having a large heat transfer area, which has been conventionally required for heat recovery from the exhaust gas cooled below the melting point of the powder. Moreover, in the spherical powder manufacturing apparatus 1 of the present invention, since the combustion exhaust gas is cooled by heat exchange, it is not necessary to introduce cooling air into the combustion exhaust gas. Thereby, since the volume of the final exhaust gas does not increase, the spherical powder production apparatus 1 of the present invention has a great merit in that the capacity of the spherical particle collection facility (such as a bag filter) can be small.

In this embodiment, the flow path length of the cooling air in the gap between the inner cylinder 8 and the outer cylinder 9 is about 5 m, and the pressure loss of the cooling air is only about 50 mmH ₂ O. For this reason, the blower 15 for supplying the cooling air can be used for a normal burner device, and the inner cylinder 8 and the outer cylinder 9 are not structurally burdened.

1 is a schematic cross-sectional view of a spherical powder production apparatus according to one embodiment of the present invention. The graph which shows the temperature change of the combustion gas, the inner cylinder, and the cooling air in the spherical powder manufacturing apparatus of FIG.

Explanation of symbols

1 ... Spherical particle production apparatus.
2 ... Flame combustion device 3 ... Furnace body 4 ... Melting chamber 5 ... Upper body 6 ... Cooling chamber 7 ... Lower body 8 ... Inner tube 9 ... Outer tube 10 ... Partition plate 11 ... Bellows (expandable member)
DESCRIPTION OF SYMBOLS 12 ... Shielding plate 13 ... Bulkhead 14 ... Intake buffer chamber 15 ... Blower 17 ... Intake pipe 19 ... Exhaust buffer chamber 20 ... Exhaust pipe 23 ... Bleed valve (combustion air adjustment means)

Claims (6)

A metal inner cylinder, an outer cylinder surrounding the inner cylinder, and a flame combustion device disposed on the upper part of the inner cylinder,
Insert cooling air into the gap between the inner cylinder and the outer cylinder ,
An apparatus for producing spherical particles , wherein cooling air that has passed through a gap between the inner cylinder and the outer cylinder is used as combustion air for the flame combustion apparatus. And characterized in that it has a combustion air amount adjusting means for a part of the cooling air passing through and emitted to the outside to adjust the amount of air supplied to the flame combustion apparatus the gap between the outer cylinder and the inner cylinder The spherical particle manufacturing apparatus according to claim 1 . Spherical particle production apparatus according to claim 1 or 2, characterized in that it has a partition plate for partitioning the gap between the outer tube and the inner tube in a spiral shape. The spherical particle manufacturing apparatus according to any one of claims 1 to 3 , wherein the inner cylinder or the outer cylinder includes a stretchable member that can be stretched in a vertical direction. The spherical shape according to any one of claims 1 to 4 , wherein the cooling air is supplied through an annular buffer chamber communicating with the inner cylinder, the outer cylinder, the gap, and the entire circumference. Particle production equipment. The cooling air is supplied to the upper portion of the gap between the outer cylinder and the inner cylinder, spherical particle production apparatus according to claim 1, characterized in that discharged from the bottom 5.

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