JP2004290762A - Method and apparatus for separating fine particles - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fine particle separating method capable of efficiently separating and recovering fine particles contained in gas and capable of facilitating the effective recycling of the recovered fine particles, and a fine particle separator therefor. <P>SOLUTION: The fine particle separating method has a gas mixing process for mixing the fine particle-containing gas with a condensible gas, a fine particle separating process for separating fine particles from the fine particle-containing gas by cooling the mixed gas produced in the gas mixing process to the condensation temperature or below of the condensible gas to condense the condensible gas using fine particles as nuclei, and a recovery process for separating the condensate condensed in the fine particle separating process using the fine particles as the nuclei and the gas from which the fine particles are removed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for separating fine particles from a gas containing fine particles by utilizing the condensation of a condensable gas and a fine particle separation apparatus.
[0002]
[Prior art]
As a method for separating and recovering fine particles from a gas containing fine particles, a method using a bag filter is a general method for recovering particulate matter.
[0003]
However, the size of the eye of the bag filter is around 1 μm, and the self-coating of dust can capture particles that are slightly smaller than the eye of the filter. However, compared to the size of the eye, the size of nanoscale particles is smaller. Since it is 1/10 to 1/1000 in size, it is difficult to recover it with a sufficient yield.
[0004]
As a method of collecting nano-scale particles, there is a method of capturing and collecting fine particles with a liquid such as water like a scrubber.However, a large amount of liquid such as water is required, which is a large economical burden, and Since it is very difficult to extract and concentrate the resulting fine particles from a large amount of liquid such as water, it is not practical.
[0005]
To cope with such a problem, Japanese Patent Application Laid-Open No. 2000-64818 (Patent Document 1) introduces an apparatus that removes soot and harmful components by condensing and liquefying exhaust gas using soot in combustion exhaust gas as a nucleus. ing.
[0006]
Japanese Patent Application Laid-Open No. 8-196851 (Patent Document 2) discloses that exhaust gas having a relative humidity of about 100% is brought into contact with a cooling liquid having a temperature lower than the exhaust gas temperature, and water vapor in the exhaust gas is introduced into the exhaust gas. A technique is described in which the contained dust is condensed as a nucleus and the removal of the dust is promoted using a mist eliminator or the like.
[0007]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 2000-64818
[Patent Document 2]
JP-A-8-196851
[Problems to be solved by the invention]
However, in the invention described in Patent Document 1, as described in the embodiment, merely reducing the exhaust gas temperature to 150 ° C. or lower may reduce the case where acidic components such as hydrochloric acid and sulfuric acid are present in the exhaust gas. As they reach the dew point, a small amount of acids condense, which is not sufficient to trap particulates in the exhaust gas. In general, the concentration of water vapor as a condensable component contained in exhaust gas ranges over a wide range of several percent to about 20%. In this temperature range, condensation of steam cannot be expected. Therefore, in the case of the invention described in Patent Document 1, it can be said that the condensable component is an acid to the last, and it is not considered that the water vapor is sufficiently condensed.
[0010]
Further, the invention described in Patent Document 2 requires the use of a cooling liquid in order to lower the temperature of exhaust gas, and the effect is sufficiently exerted if contact mixing of the dust-containing gas and the cooling liquid is not performed smoothly. Can not do it. Also, the use of a large amount of coolant to increase the contact ratio between the coolant and the dust-containing gas results in dispersing fine particles dilutely in a large amount of cooling liquid as in the case of using a scrubber. Therefore, there is a great problem in collecting and utilizing the fine particles thereafter.
[0011]
The present invention has been made in order to solve the above problems, and a fine particle separation method and fine particles capable of efficiently separating and recovering fine particles contained in a gas and facilitating effective use of the fine particles after the recovery. It is an object to provide a separation device.
[0012]
[Means for Solving the Problems]
The above problem is solved by the following invention.
[1] A method for separating fine particles from a gas containing fine particles, wherein a gas mixing step of mixing the fine particle-containing gas and a condensable gas, and a condensing of the mixed gas generated in the gas mixing step with the condensable gas Cooling to a temperature or less, a fine particle separation step of separating fine particles from the fine particle-containing gas by condensing the condensable gas with the fine particles as nuclei, and a condensate and fine particles obtained by condensing fine particles as nuclei in the fine particle separation step A recovery step of separating and recovering the removed gas.
[2] In the above [1], adding at least one of an electric field, a magnetic field, a temperature field, a centrifugal force, gravity, ultrasonic waves, and a liquid flow to the liquid condensate recovered in the recovery step. And a fine particle collection step of separating and collecting the fine particles from the condensate.
[3] In the above [1] or [2], the method of cooling the mixed gas in the fine particle separation step to a temperature equal to or lower than the condensation temperature of the condensable gas is performed by adiabatically expanding the mixed gas to a temperature lower than the condensation temperature of the condensable gas. A method for separating fine particles, which comprises cooling.
[4] An apparatus for separating and recovering fine particles from a gas containing fine particles, comprising: a gas mixing means for mixing the fine particle-containing gas and the condensable gas; and condensing the mixed gas generated by the gas mixing means into a condensable gas. An apparatus for separating fine particles, comprising: a cooling means for cooling to a temperature not higher than a temperature; and a collecting means for separating and collecting a condensate cooled by the cooling means and condensed with fine particles as nuclei, and a gas from which the fine particles have been removed.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a schematic configuration diagram showing one embodiment of a particle separation device according to the present invention.
[0014]
A particle separation apparatus 1 shown in FIG. 1 includes a gas mixing means 2 for mixing a fine particle-containing gas and a condensable gas, and a cooling means for cooling the mixed gas generated by the gas mixing means 2 to a temperature not higher than the condensation temperature of the condensable gas. And a recovery means 4 for separating and recovering a condensate cooled by the cooling means 3 and condensed with the fine particles as nuclei, and a gas from which the fine particles have been removed.
[0015]
In the gas mixing means 2, the fine particle-containing gas and the condensable gas are mixed. Here, as the condensable gas, a gas that is condensed and liquefied by lowering the gas temperature to a specific temperature, for example, steam, alcohol, ether, acetone, vapor of another organic solvent, or easily by adiabatic expansion. Liquefied or condensed carbon dioxide gas or the like can be used.
[0016]
The gas mixed in the gas mixing means 2 is then introduced into the cooling means 3. In the cooling means 3, the temperature of the mixed gas is cooled to a temperature lower than the condensation temperature of the condensable gas contained in the mixed gas. Here, as the cooling means 3, for example, a means for performing a process such as adiabatic expansion of a mixed gas and lowering the temperature to a temperature equal to or lower than the condensation temperature of the condensable gas can be used. Also, carbon dioxide gas can be used as the condensable gas.
[0017]
When the condensable gas condenses, the fine particles contained in the mixed gas are condensed as nuclei. As described above, by condensing the condensable gas with the fine particles as nuclei and recovering the condensed gas, the fine particles can be separated from the fine particle-containing gas.
[0018]
FIG. 2 shows an image diagram when the condensable gas is condensed by using fine particles contained in the mixed gas as nuclei.
[0019]
In FIG. 2, (a) shows a state in which a condensable gas is mixed with a gas containing fine particles. (B) shows a state in which the condensable components of the condensable gas aggregate with the fine particles contained in the mixed gas as nuclei in the cooling process. (C) shows a state in which the condensable components are aggregated and separated from the gas.
[0020]
As described above, in the present invention, a condensable gas such as water vapor is preliminarily mixed with the fine particle-containing gas, and the temperature of the mixed gas is reliably reduced to a temperature equal to or lower than the dew point of the condensable component in the condensable gas by the cooling means 3. By lowering, the condensable components in the condensable gas are condensed with the fine particles in the gas as nuclei, and the fine particles are aggregated together with the condensable component, and separated from the gas as a condensate to efficiently reduce the fine particles in the gas. Can be collected.
[0021]
In the invention of the present application, with the above configuration, it is possible to easily control the amount of the condensable gas mixed with the fine particle-containing gas and the cooling temperature of the cooling means 3. This makes it possible to easily control the amount of condensate liquefied, so that it is possible to efficiently recover the liquid state in which the fine particles are aggregated.
[0022]
The mixing ratio of the condensable gas mixed with the fine particle-containing gas is 30% or more of the amount of the fine particle-containing gas, and in some cases, several times as much. This requires the mixing of a condensable gas of 30% or more in order to allow the condensation to proceed easily and uniformly.
[0023]
For example, when water vapor is used as the condensable gas mixed with the fine particle-containing gas, the condensing ratio of the water vapor in the cooling step is set to about 20 to 80%. It is desirable that the temperature is not higher than 10.degree.
[0024]
The amount of the condensable gas mixed with the fine particle-containing gas and the cooling temperature of the cooling means 3 can be appropriately selected in consideration of the fine particle concentration in the fine particle-containing gas and the like.
[0025]
The collecting means 4 separates and collects the gas from which the condensate and fine particles have been removed. Here, the condensate is recovered by the condensate recovery means 4a, and the gas from which the fine particles have been removed is recovered by the gas recovery means 4b.
[0026]
The condensate collecting means 4a may be constituted by, for example, a condensate outlet provided at a lower portion of the fine particle separation device 1, a storage tank for storing the condensate, a pipe connecting the condensate outlet and the storage tank, and the like. Can be. Further, the gas recovery means 4b may be constituted by, for example, a gas outlet provided on a side wall of the particle separation device 1, a storage tank for storing gas, a pipe connecting the gas outlet and the storage tank, and the like. it can. In addition, by mixing the gas discharged from the gas discharge port with the condensable gas again and returning the mixed gas to the inside of the fine particle separation device 1, it is possible to more effectively remove the fine particles in the gas.
[0027]
In the liquid condensate recovered by the condensate recovery means 4a, fine particles separated from the gas exist in a suspended state. By adding one or more of electric field, magnetic field, temperature field, centrifugal force, gravity, ultrasonic wave and liquid flow to this liquid condensate, the fine particles are laminated and other generally regular forms are added. Can be aggregated (arranged). By evaporating and removing the liquid condensed component in a state in which the fine particles are aggregated (arranged), or by using a resin for fixing the aggregate, a low melting point substance, an adhesive, a binder, or the like. By fixing and separating the fine particles, the separated and collected fine particles can be used as a material for a functional material as it is.
[0028]
The liquid condensate recovered by the condensate recovery means 4a needs to be maintained at a temperature equal to or higher than the melting point of the condensable component. If necessary, a heating means is provided in a storage tank for storing the condensate. It may be provided.
[0029]
Here, by applying an electric field when the fine particles are a substance having high conductivity, or applying a magnetic field when the fine particles have magnetic properties, not only separation from a liquid as a solvent is facilitated, but also Alternatively, the fine particles to be aggregated can be collected in a certain regular arrangement or lamination depending on the direction of application of the magnetic field.
[0030]
In addition, since the specific gravity is generally different between the liquid serving as the solvent and the collected fine particles, the sedimentation or flotation is further promoted by adding an inertial force such as a temperature field, centrifugal force, or gravity. Becomes possible.
[0031]
Further, by applying the ultrasonic wave under the condition that cavitation is not generated, the fine particles aggregate, so that the separation due to the difference in specific gravity can be promoted. On the other hand, in the case of uniformly laminating or arranging the fine particles, the fine particles need to be uniformly dispersed in the solvent, so that the solvent is evaporated while applying the ultrasonic wave under the condition that cavitation occurs. The fine particles can be recovered in a dispersed state.
[0032]
It is also possible to utilize the promotion of migration of fine particles by using a temperature field as one of the means for controlling the flow of the liquid.
[0033]
In this way, the collected liquid condensate is given an electric field, a magnetic field, a temperature field, a centrifugal force, gravity, ultrasonic waves, or a liquid flow alone or in combination, so that the fine particles to be collected are laminated, and the like. Aggregation (arrangement) into a generally regular form is possible.
[0034]
In addition, as the above-mentioned collecting means 4, a gas from which condensate and fine particles have been removed can be separated and collected by a cyclone, a bag filter, or other ordinary dust removing means. When the particle size of the condensate has been condensed to at least 0.1 μm or more, desirably 1 μm or more, dust is removed by a filter type dust removing device such as a bag filter to separate and collect the fine particle condensate and gas. can do. When the condensate has a particle diameter of at least 10 μm or more, preferably 20 μm or more, and more preferably 40 μm or more, the dust is removed by a cyclone dust remover to separate and collect the fine particle condensate and gas. Can be.
[0035]
The fine particles that are nanomaterials can be efficiently and inexpensively recovered according to the above-described embodiment. Therefore, the fine particles recovered as electronic device equipment, paint, medical use, and other functional materials can be used, and the economic effect is large. .
[0036]
【The invention's effect】
As described above, according to the present invention, there is provided a particle separation method and a particle separation apparatus capable of efficiently separating and collecting fine particles contained in a gas and facilitating effective use of the collected fine particles. Is done.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing one embodiment of a particle separation device according to the present invention.
FIG. 2 is an image diagram when the condensable gas according to the present invention is condensed with fine particles contained in a mixed gas as nuclei.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Particle separation apparatus 2 Gas mixing means 3 Cooling means 4 Recovery means 4a Condensate recovery means 4b Gas recovery means

Claims (4)

A method for separating fine particles from a gas containing fine particles,
A gas mixing step of mixing the fine particle-containing gas and the condensable gas,
Cooling the mixed gas generated in the gas mixing step to a condensation temperature of the condensable gas or lower, and condensing the condensable gas with the fine particles as nuclei, thereby separating the fine particles from the fine particle-containing gas;
A method for separating and collecting a condensate obtained by condensing fine particles as nuclei in the fine particle separation step and a gas from which the fine particles have been removed. By adding one or more of an electric field, a magnetic field, a temperature field, a centrifugal force, gravity, an ultrasonic wave, and a liquid flow to the liquid condensate recovered in the recovery step, fine particles in the condensate are reduced. An aggregation step of aggregating,
2. The method for separating fine particles according to claim 1, further comprising a fine particle collecting step of separating and collecting the aggregated fine particles from a condensate. 2. The method of cooling a mixed gas to a temperature not higher than the condensation temperature of the condensable gas in the fine particle separation step, wherein the mixed gas is cooled to a temperature lower than the condensation temperature of the condensable gas by adiabatically expanding the mixed gas. Alternatively, the method for separating fine particles according to claim 2. An apparatus for separating and recovering fine particles from a gas containing fine particles,
Gas mixing means for mixing the fine particle-containing gas and the condensable gas,
Cooling means for cooling the mixed gas generated by the gas mixing means to a temperature not higher than the condensation temperature of the condensable gas,
A fine particle separation apparatus comprising: a collecting means for separating and collecting a condensate cooled by the cooling means and condensed with the fine particles as nuclei, and a gas from which the fine particles have been removed.

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