JPS62294413A - Collecting device for fine particle - Google Patents

Abstract

PURPOSE:To mold and remove scattering fine particles without allowing them to fly off out of a system, by providing a molding device to separate fine particles charged through a nozzle together with a carrier gas by means of a filter, and pile up into a fixed shape. CONSTITUTION:An upstream chamber 5 and a downstream chamber 6 are communicated with each other through a nozzle 1, and the downstream chamber 6 is communicated with a molding device 4. The molding device 4 can rotate in the horizontal direction in a collecting tank 9, forming a filter 3 on its peripheral side. Fine particles 2 discharged through a nozzle 1 are fed into the molding device 4 by the injection from the nozzle 1 without diffusing much. Accordingly, fine particles 2 are diffused between the nozzle 1 and the molding device 4 to be prevented from scattering off out of the system. The fine particles 2 fed into the molding device 4 are molded in the molding device 4 and removed, and so they can be handled easily after having been removed therefrom.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an apparatus for collecting fine particles that are easily scattered. Furthermore, L< can be produced by gas phase reaction methods such as in-gas evaporation method, plasma evaporation method, and gas phase chemical reaction method, and by liquid phase reaction methods such as colloidal precipitation method and solution spray pyrolysis method. Ultra-fine particles (generally 0.5 μm particle size) are expected to be applied to the formation of composite materials and fine ceramic materials.
The following) relates to a device suitable for collecting fine particles (generally referred to as "ultrafine particles").

[Prior Art] Conventionally, as particulate collecting devices, there are known devices that utilize a cyclone and devices that spray a dispersion medium in a shower in order to also collect floating particles.

[Problems to be solved by the invention] However, with conventional collection devices, the amount of particles that cannot be completely collected and is used outside the system increases, especially when it comes to small particles such as ultrafine particles. There is a problem. This increase in lost particulates not only reduces the amount of collected particulates, but also causes the particulates to drift in the air.
Causes adverse effects on the human body.

In the case of ultrafine particles, effective collection has not yet been established because their particle size is extremely small and their history is relatively short.

[Means for Solving the Problems] The means purchased to solve the above problems will be explained with reference to FIG. 1, which corresponds to an embodiment of the present invention. The above-mentioned problem is solved by using a particulate collecting device having a molding device 4 on the side that separates the particulates 2 sent together with the carrier gas through the nozzle 1 with a filter 3 and deposits them in a predetermined shape. It is.

[Function] The fine particles 2 sent out through the nozzle 1 are ejected from the nozzle 1 and sent into the molding machine 4 without significant diffusion. Therefore, it is possible to prevent the fine particles 2 from diffusing between the nozzle 1 and the molding machine 4 and easily scattering out of the system. In addition, since the fine particles 2 fed into the molding machine 4 are molded by the molding machine 4 and then taken out, the handling properties after taking them out from the molding machine 4 are good, and the fine particles 2 are easy to handle when taken out from the molding machine 4 and afterward. It is also possible to prevent the fine particles 2 from scattering.

[Example] As shown in FIG. 1, the L flow chamber 5 and the downstream chamber 6 are communicated through the nozzle 1, and the downstream chamber 6 is connected to the molding machine 4.
is communicated with.

The molding machine 4 is connected to a pump 8 via a valve 7 and housed in a collection tank 9, and the water 1 is collected in the collection tank 9.
It is rotated in one direction. In addition, a filter 3 is provided around the molding machine 40, and a collection tank 9 is connected to the pump 8.
By eliminating air inside the molding machine 4, the pressure inside the molding machine 4 and further inside the downstream chamber 6 can be reduced through the filter 3.

The upstream chamber 5 is configured to eject the lIk particles 2 to the downstream chamber 6 side through the nozzle 1 due to a pressure difference between the upstream chamber 5 and the downstream chamber 6 side due to the operation of the pump 8 . This upstream chamber 5 may also serve as a generating device for the fine particles 2, or may receive the fine particles 2 generated by another generating device.

The fine particles ejected from the upstream chamber 5 to the downstream chamber 6 through the nozzle L are fed into the molding device 4 which faces the nozzle 1 and communicates with the downstream chamber 6, and is filtered by the rotation of the molding device 4. The fine particles 2 are uniformly deposited on the inner surface of the
The carrier gas that has flowed together passes through the filter 3 and is discharged by the pump 8. The fine particles 2 deposited and molded on the inner surface of the filter 3 in this way are transferred to the lid 1 of the molding machine 4.
It is taken out by opening 0.

As the filter 3 of the molding machine 4, fluoride resin, aluminum sintered material, etc. can be used. In order to improve the moldability of the fine particles 2, it is preferable to provide a binder supply device 11 in the downstream chamber 6, which jets out a binder such as a coagulant that is sent into the molding machine 4 together with the fine particles 2 flowing through.

The binder is preferably supplied in the form of mist or vapor. In addition, fine particles 2 ejected from the nozzle 1
It is preferable to provide a shutter 12 that can move forward and backward with respect to the flow path, since this makes it easier to control the start and stop of supply of the fine particles 2 to the molding device 4.

Although the nozzle 1 may be a parallel nozzle or a tapered nozzle, it is preferably a contracting/expanding nozzle as shown in an enlarged view in FIG. This contracting/expanding nozzle is one in which the opening area is gradually narrowed from the inlet 1a to become the throat IC, and the opening area is expanded again to become the outlet 1b.

The contraction/expansion nozzle controls the pressure P of the upstream chamber 5. By adjusting the pressure ratio P/PO of the pressure P of the downstream chamber 6 and the ratio A/A'' of the opening area A' of the throat portion 3c and the opening area A of the outlet 1b, the amount of fine particles 2 ejected can be adjusted. The flow can be sped up.

If the pressure ratio P/PO in the upstream chamber 5 and the downstream chamber 6 is greater than the critical pressure ratio, the outlet flow velocity of the contraction-expansion nozzle becomes subsonic flow or less, and the fine particles 2 are decelerated and ejected. Further, if the pressure ratio is equal to or lower than the critical pressure ratio, the outlet flow velocity of the contraction/expansion nozzle becomes supersonic, and the fine particles 2 can be ejected at supersonic speed.

Here, if we assume that the velocity of the flow is U, the sound velocity at that point is a, the specific heat ratio of the flow is γ, and the flow is a compressible one-dimensional flow with adiabatic expansion, the Matsuha number M reached by the flow is It is determined by the following formula from the pressure Po in the chamber 5 and the pressure P in the downstream chamber 6. In particular, when P/PO is less than the critical pressure ratio, M is less than l-4.
It becomes two.

Note that the speed of sound a can be determined by the following equation, where 'ro is the local temperature and R is the gas constant.

, r〒11 Also, the following relationship exists between the opening surface viA of the outflow port 1b, the opening surface tiA' of the throat portion 1c, and the Matsuha number M.

Therefore, the pressure P in the upstream chamber 5. The opening area ratio A/A'' is determined according to the Matsuha number M determined from equation (1) by the pressure ratio P/Po of the pressure P of the downstream chamber 6, and MK determined from equation (2) by A/A◆. By adjusting P/POt-, the flow ejected from the enlargement/reduction nozzle can be ejected as a properly expanded flow.The speed U of the flow at this time can be determined by the following equation (3).

When the fine particles 2 are ejected in a fixed direction as a properly expanded flow of supersonic speed as described above, the fine particles 2 travel straight while maintaining almost the jet cross section immediately after being ejected, and are formed into a beam. As a result, the fine particles 2 are ejected through the space within the downstream chamber 6 with minimal diffusion, in a spatially independent state without interference with the wall surface of the downstream chamber 6, and at supersonic speed. Therefore, waste caused by fine particles -r-2 adhering to the inner wall of the F flow chamber 6 can be reliably prevented.

When using a contraction/expansion nozzle as the nozzle 1, as shown in Fig. 2 (
As shown in a), it is preferable that the inner circumferential surface is substantially parallel to the central axis at the position of the outlet 1b. This is because the flow direction of the ejected fine particles 2 is influenced by the direction of the inner circumferential surface of the outflow rllb, so the purpose is to make parallel flow as easy as possible. However, Fig. 2(b)
As shown in FIG.
If the angle is less than 1°, the separation phenomenon will hardly occur and the flow of ejected particles will be maintained almost uniformly, so in this case, it is not necessary to make them parallel as in 1- above.

By omitting the formation of the parallel portion, it becomes easy to manufacture the contraction/expansion nozzle.

Here, the separation phenomenon refers to a phenomenon in which when there is a protrusion etc. on the inner surface of the contraction/expansion nozzle, the boundary layer between the inside of the contraction/expansion nozzle and the flowing fluid becomes large and the flow becomes non-uniform. , the higher the speed of the jet flow, the more likely it is to occur. In order to prevent this peeling phenomenon, it is preferable that the above-mentioned angle α is made smaller as the inner surface finishing precision of the contraction/expansion nozzle is inferior. The inner surface of the contraction/expansion nozzle preferably has three or more, most preferably four or more, inverted triangular marks indicating surface finish accuracy as defined in JIS B 0801. In particular, the peeling phenomenon at the enlarged part of the condensing/expanding nozzle greatly affects the subsequent flow of the film-forming gas, so by determining the finishing accuracy above with emphasis on this enlarged part, the fabrication of the constricting/expanding nozzle can be made easier. can.

In addition, in order to prevent the occurrence of peeling phenomenon, the throat portion 1c is made a smooth curved surface, and the differential coefficient of the cross-sectional area change rate is
It is necessary to make sure that this does not happen.

Materials for the contraction/expansion nozzle include iron, stainless steel, and other metals, as well as synthetic resins such as tetrafluoroethylene, acrylic resin, polyvinyl chloride, polyethylene, polystyrene, and polypropylene, and ceramic materials.
, quartz, glass, etc. can be widely used. The material may be selected in consideration of non-reactivity with the fine particles -f-2, workability, gas release properties in a vacuum system, and the like. Also,
The inner surface of the contraction/expansion nozzle may be plated or coated with a material that is less likely to cause adhesion and reaction of the fine particles 2. Specific examples include coatings of polyfluoroethylene and ceramic materials.

[Effects of the Invention] According to the present invention, fine particles that are easily scattered can be taken out after being molded in a series of systems, and scattering of the fine particles outside the system can be prevented, thereby reducing collection efficiency due to scattering. It can prevent deterioration of the surrounding environment. Moreover, since it is molded and taken out, it is easy to handle it afterwards and it can also prevent it from scattering at that time. Further, by using a contraction/expansion nozzle as a nozzle, the diffusion of the particle flow can be minimized, and the collection efficiency and time can be significantly improved.

From the above, the present invention not only improves the collection efficiency of fine particles and facilitates handling, and can be applied to ceramic technology, but also has the potential to be used in the production of new materials.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of an embodiment of the present invention, FIG. 2(a),
(b) is a sectional view showing an example of each nozzle. 1: nozzle, 2: fine particles, 3: filter. 4: Forming machine, 5: Upstream chamber, 6: Downstream chamber, 7: Valve, 8
: Pump, 9: Collection tank, 10: Lid, 11: Binder supply device, 12: Shutter.

Claims (1)

[Claims] 1) A particulate collection device comprising a nozzle and a molding machine downstream of the nozzle that separates the particulates sent together with the carrier gas through the nozzle with a filter and deposits them in a predetermined shape.