JPH08173740A - Mist removing apparatus - Google Patents

Abstract

PURPOSE: To separate mist efficiently from gas containing mist with various particle sizes and to use over a long period of time while clogging being controlled even when the gas containing mist flows intermittently. CONSTITUTION: An apparatus has an airtight chamber 5 equipped with an introduction pipe 1 for gas containing mist, the first channel pipe 2 which is aligned with the pipe 1 and the inlet of which is separated by a slit from the outlet of the pipe 1 and opened in the chamber 5, a baffle plate 7 installed in the pipe 2, the first filter 8 installed downstream from the baffle plate 7, the second channel pipe 3 the inlet of which is opened in the chamber 5, and the second filter 9 which is installed in the pipe 3 and has a smaller pressure loss than the first filter 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mist removing device for separating and removing mist, which is minute liquid droplets floating in a gas.

[0002]

2. Description of the Related Art Among droplets and mists generated in various industrial processes, droplets or mists floating in a gas such as blow-by gas of an internal combustion engine or oil mist in compressed air of an air drive unit, the particle size is about Droplets of 20 μm or more are almost completely separated by a gravity separator that collects by utilizing natural sedimentation or an inertial separator that collects by colliding with an obstacle such as a baffle plate inserted in a gas flow path. It can be removed.

However, it is difficult to separate minute droplets called mist having a particle size of 10 to 20 μm or less by a gravity separator or an inertial separator. In particular, oil mist contained in blow-by gas in an internal combustion engine such as an automobile engine cannot be separated and removed by a removing device using gravity or inertial force because the particle size is extremely fine, about 1 μm or less.

For the separation of such mist, a filtration / separation device for collecting with a filter medium, or a device for separating by causing relative motion between gas and mist, typically a separation device utilizing a centrifugal force (cyclone) ) Was used. However, in the filtration / separation device, since the furnace material such as the filter cloth or the fiber-filled layer is arranged in the gas flow path, the separation efficiency is increased, but the pressure loss is increased and clogging is likely to occur.
On the other hand, in the cyclone separator, on the contrary, the pressure loss is small and clogging is unlikely to occur, but it has a drawback that fine mist of about 1 μm or less cannot be separated unless a large centrifugal force or a sufficiently long residence time is applied.

In addition, charged particles have the property of moving in the direction of an electrode having a polarity opposite to that of the charged particles in an electric field. An electric separation device for separating mist by utilizing this electrostatic force is also known. However, although this device can separate fine mist, it has a major drawback that it cannot be used unless the mist is charged. I couldn't.

[0006]

As described above, in the conventional mist separating device for separating minute droplets or mist in the gas, if the separation efficiency is increased, pressure loss or clogging easily occurs, and conversely, pressure loss occurs. In addition, when the clogging is reduced, the separation efficiency is lowered, and it is difficult to separate and remove the mist with high separation efficiency with a relatively simple device without pressure loss and clogging.

Under these circumstances, the inventors of the present invention, in Japanese Patent Application No. 6-276022, collect mist in a gas to make it into coarse particles, and re-reproduce it in the gas as coarse mist or droplets. Proposed a coarse-grained filter that scatters, and
No. 251279 proposes a mist removing device for separating coarse particle mist or droplets re-scattered from the coarse particle filter from gas by combining the coarse particle filter with a conventional mist separating apparatus.

However, the function of the above-mentioned coarse-grained filter is exerted without any trouble while the air flow is continuously flowing by the operation of the engine or the like, but when the air flow stops due to the stop of the operation or the like, the filter adheres. The mist continues to form an oil film or a liquid film, which is difficult to separate from the fibers of the coarse-grained filter. Therefore, this oil film or liquid film easily causes clogging, and when the operation is restarted, the pressure loss rapidly increases,
There are inconveniences such as a decrease in collection efficiency.

In addition, general mist such as oil mist in blow-by gas usually contains mist of various particle sizes from fine particles to coarse particles, and further, coarse foreign matters such as sludge are included. Sometimes it is. As a result, if the flow of the air flow stops with the coarse mist adhering, the clogging becomes more severe, and the clogging also occurs due to the foreign matter adhering to the coarsening filter.

Therefore, when the flow of the mist-containing gas is intermittent, such as the blow-by gas of an automobile engine which is repeatedly operated and stopped, clogging is likely to occur, and therefore the life of the coarse-grained filter is shortened. Cheap.

In view of the above situation, the present invention is capable of efficiently separating and removing mist from a mist-containing gas containing mist of various particle diameters, and also when the flow of the mist-containing gas is intermittent. An object of the present invention is to provide a mist removing device that is unlikely to cause clogging and can be used for a long period of time.

[0012]

In order to achieve the above object, a mist removing device proposed by the present invention has an airtight chamber provided with an inflow pipe for a flow of a mist-containing gas, and the inflow pipe and the axial center line of the airtight chamber. A first flow path pipe having an inlet opening in the airtight chamber with a slit interval from the inflow pipe outlet, a baffle plate provided in the first flow channel pipe and a first filter provided downstream of the baffle plate, and an inlet being the airtight chamber And a second filter having a smaller pressure loss than the first filter provided in the second flow path pipe.

Second Embodiment Used in the Mist Removal Device of the Present Invention
Is a coarse-grained filter previously proposed by the present inventors by Japanese Patent Application No. 6-276022, that is, a plurality of single fibers or fiber yarns arranged substantially parallel to each other at intervals. It is preferable that the filter is made of a coarse particle filter that collects mist in the gas to make it into coarse particles and re-disperses it in the gas as coarse particle mist or droplets. The diameter of the single fiber or fiber thread of the coarse-grained filter is 100 μm.
It is below, and the filling rate is preferably 5% or less.

Here, the single fibers mean filaments such as silk and chemical fibers, and short fibers (staple) such as cotton, wool, and chemical fibers, and the fiber yarn is a collection of several such single fibers. It means a twisted or spun yarn. Fiber yarn consists of one type of monofilament,
It may consist of two or more types of monofilaments.

[0015]

In the mist removing device of the present invention, since the outlet of the inflow pipe and the inlet of the first flow passage pipe whose axial center line coincides with each other are arranged at a slit interval, the inflow is caused by suction or the like. The mist-containing gas stream flowing through the pipe is the first
Instead of flowing into the flow tube, most of it flows into the airtight chamber and enters the second flow tube. At that time, the mist at the center of the mist-containing gas flow goes straight into the first flow path pipe regardless of the particle size, but the mist in the other part changes its flowing direction depending on the particle size.

For the sake of simplicity, referring to FIG. 3,
The mist-containing gas flow is sucked from the first flow path pipe 2 and the second flow path pipe 3 side, flows in the inflow pipe 1, and reaches the outlet thereof.
At that time, the mist existing in the central portion of the mist-containing gas flow rides on the flow in the central portion of the gas flow regardless of the particle size, and the first flow pipe 2
However, the flow of mist that exists outside the central part differs depending on the particle size.

That is, the mist having a large particle diameter advances straight by a large inertial force and flows into the first flow path pipe 2. On the other hand, the mist having a small particle diameter flows out into the airtight chamber 5 through the slit 4 between the outlet of the inflow pipe 1 and the inlet of the first flow pipe 2, is sucked and flows into the second flow pipe 3. Further, the mist having an intermediate particle diameter often collides with the tube wall of the first flow path tube 2 in addition to any of the above flows. In order to create such a gas flow,
It is necessary to make the pressure loss of the second filter smaller than that of the first filter so that the flow rate of the second flow path pipe is higher than that of the first flow path tube.

The classification of mist due to these differences in particle size is
Inlet pipe 1 of the inner diameter D ₁ and the first flow pipe 2 of an inside diameter D ₂ (D ₁ = D ₂
Often) of the slit spacing S, and the flow rate of the mist-containing gas stream, i.e. the flow rate to Q ₁ inlet pipe 1, the flow rate Q ₂ of the first flow pipe 2, the flow rate Q ₃ of the second flow pipe 3, It is possible to control. Each flow rate of the mist-containing gas flow is adjusted depending on the degree of suction, the degree of pressure loss due to the filters arranged in the first and second flow pipes 2, 3.

Actually, the state of classification of gas streams containing mists having different particle diameters was confirmed using the apparatus shown in FIG. In this classification test, inflow pipe inner diameter D ₁ = first flow passage pipe inner diameter D ₂ = 10 mm, slit interval S = 2.3 mm, inflow pipe flow rate Q ₁ = 128.3 liter / min, first flow passage pipe flow rate Q ₂ =
The flow rate of the second flow path pipe was set to 28.3 liters / minute and Q ₃ = 100 liters / minute.

As the mist-containing gas, an oil mist generated under the conditions of an air pressure of 2.3 kgf / cm ² , an oil droplet shot rate of 4 shots / minute, and an oil temperature of 30 ° C. is obtained by using a commercially available mist generator. It includes. The median diameter d ₅₀ of this oil mist (particle diameter at which 50% of the weight is accumulated) is 1.3.
Is about 1.4 μm. The particle size and the amount of oil mist are measured by an impactor type aerosol particle size distribution measuring device (MODEL AN- manufactured by Tokyo Dylec Co., Ltd.).
2100) was used to measure the amount of particles collected by a collection plate installed for each predetermined particle size.

The results of the above classification test are shown in FIG. FIG.
In the graph, the solid line indicates the mist flowing out from the slit 4 and obtained from the second flow pipe 3, and the broken line indicates the mist obtained from the first flow pipe 2. It can be seen that the particle size of the mist entering the first flow path pipe 2 is often larger than the particle size of the mist entering the second flow path pipe 3.

According to the present invention, as described above, the mist having a large particle size can be mainly introduced into the first flow path pipe, and the mist having a small particle size can be mainly introduced into the second flow path pipe. it can. As a result, among the mists flowing into the first flow path pipe, the mist having a large particle size collides with the baffle plate by the inertial force and is removed, and the mist that has not collided with the baffle plate is collected by the first filter. It On the other hand, the mist mainly having a small particle size, which has flowed into the second flow pipe, is directly collected by the second filter.

The first filter may be an ordinary filter having a large pressure loss, and for example, a filter made of cloth or woven fabric, a filter filled with various fibers, a so-called membrane filter made of a porous membrane or the like can be used.

On the other hand, the second filter must have a smaller pressure loss than the first filter. Therefore, it is desirable that a plurality of second filters be arranged along the axial direction of the second flow path pipe. The second filter may be a cloth or woven filter having a low filling rate, a fiber-filled filter, or the like, but the above-described coarse-grained filter is preferable.

The mist having a small particle size flowing into the second flow path pipe is difficult to be completely collected by a filter having a small pressure loss, that is, a coarse mesh.
The mist having a small particle size adheres to and coalesces or coalesces on the coarse-graining filter, and becomes a coarse-particle mist having a large particle size and can be re-scattered. Therefore, even a fine mist becomes a coarse-grained mist having a large particle size, and by disposing the baffle plate downstream thereof, the mist can be completely removed.

A preferred structure of the coarse-grained filter is that a plurality of monofilaments or fiber yarns are arranged on one plane parallel to the lengthwise direction and spaced apart from each other in a comb shape, and are fixed at both ends thereof. , Or a structure in which both ends are opened and fixed by a thread-like support material composed of single fibers or fiber threads arranged substantially at right angles to each single fiber or fiber thread.

The monofilament or fiber thread constituting the coarse filter is not particularly limited, and examples thereof include natural fibers such as cotton, hemp, wool and silk, regenerated fibers such as rayon, semi-synthetic fibers such as acetate, nylon. , Organic synthetic fibers such as polyester, acrylic, polyethylene, polypropylene, and aramid, or inorganic synthetic fibers such as glass fiber, carbon fiber, metal fiber, and ceramic fiber. Of these, monofilaments or spun yarns of these fibers are preferable. The spun yarn is suitable for collecting mist because a large number of single fibers are projected around the spun yarn.

In order to improve the collection efficiency of the coarse-grained filter, the thickness of the monofilament or fiber thread constituting the collector is reduced, the packing rate is increased, or the gas flow passage speed is increased. Is effective. However, if the filling rate is increased, pressure loss increases and clogging is likely to occur. Therefore, a single fiber or a fiber yarn is used so that high collection efficiency can be achieved with little pressure loss and without causing clogging. The arrangement and the arrangement are selected in consideration of the thickness and the filling rate. Further, it is preferable to arrange or arrange the single fibers or the fiber threads of the interdigital fiber layers between the coarse-grained filters adjacent to each other so as not to overlap each other in the flow direction of the gas flow.

[0029]

EXAMPLE As a specific example of the mist removing apparatus according to the present invention, the apparatus shown in FIG. 1 was produced. This mist removing device is provided with an inflow pipe 1 for a gas flow of a mist-containing gas on one side surface of a cylindrical body 6 made of an acrylic resin, and the inflow pipe 1 and the axial center line are aligned with each other so that the first flow is introduced into the cylindrical body 6. The conduit 2 is arranged. Both the inner diameter of the inflow pipe 1 and the inner diameter of the inlet of the first flow passage pipe 2 are 10 m
The gap of the slit 4 between the outlet of the inflow pipe 1 and the inlet of the first flow passage pipe 2 was set to 2 mm.

Inside the first flow path pipe 2, a baffle plate 7 is arranged on the upstream side, and a first filter 8 made of a woven fabric is arranged on the downstream side of the baffle plate 7. The baffle plate 7 is made of a nylon resin plate, and its radius is 15 mm, which is the same as the inner diameter of the first flow path pipe 2.
And, the upper part is cut out in a semicircular shape by 3 mm from the apex. The first filter 8 has a diameter of 40 μm.
423 weft yarns / inch and two 254 warp yarns with a diameter of 40 μm made of polyester woven fabric.

The inside of the cylindrical body 6 is partitioned by a partition wall in the middle of the first flow path pipe 2, and the airtight chamber 5 on the slit 4 side of the partition wall.
The second flow path pipe 3 is open at. The inner diameter of the second flow pipe 3 is 12 mm, and the first filter 8 is provided inside the second flow pipe 3.
As the second filter 9 having a smaller pressure loss, 18 layers (50 mm in length) of coarse-grained filters are arranged.

As shown in FIG. 2, in each coarse-grain filter, nylon monofilaments 12 having a diameter of 30 μm, which are wefts, are arranged parallel to each other in a longitudinal direction on a plane at intervals of 18 μm. Each of the nylon monofilaments 12 is fixed by weaving a die rod with three thread-shaped support members 13 made of a nylon monofilament having a diameter of 30 μm and arranged in a direction perpendicular to each other.
In addition, each nylon monofilament 12 is composed of a comb-shaped fiber layer in which both ends are open, and two comb-shaped fiber layers are 5 m in length.
Parallel to each other at an interval of m and each nylon monofilament 1
Place them on one plane so that they do not overlap as much as possible,
It is fixed to a frame body 14 having a diameter of 12 mm.

Further, a suction pipe 11 having a radius of 10 mm is attached to the cylindrical body 6 so as to face the outlet of the first flow passage pipe 2. or,
At the outlet of the second flow path pipe 3 inside the cylindrical body 6, the suction pipe 11
A baffle plate 10 having a radius of 50 mm that reaches the entrance of is arranged.

The oil mist-containing gas generated by a commercially available mist generator is fed to the suction pipe 1 in the mist removing device.
It was supplied by suction from 1. The oil mist generator used was a MicronLube C manufactured by TACO.
It is a PS lubrication unit. Idemitsu Kosan Co., Ltd. as oil
Using the Daphney Super Multi 32 of No. 5, JIS Z8901 type 5 fly ash (median diameter 13 to 17 μm) was dispersed in this oil.

The conditions for generating oil mist are air pressure of 1.
5 kgf / cm ² , 4 shots / minute of oil drops,
At an oil temperature of 30 ° C., an aerosol in which dust with a median diameter of 14.6 μm and oil mist with a median diameter of 1.45 μm were mixed was generated.

This aerosol (oil mist-containing gas)
Was allowed to flow through the inflow pipe 1 of the mist removing device for 8 hours, and then a cycle of resting for 16 hours was continued for 7 days to evaluate the collection performance. The temperature in the airtight chamber 5 during the inflow of the aerosol is about 30 ° C., and the temperature in the airtight chamber 5 at rest is −1.
It was kept at 0 ° C.

In addition, as a comparative example, a flow path tube having the same 18-layer coarse-graining filter as described above and the same baffle plate as described above arranged at the outlet of the flow path tube are used as an inflow tube and a suction tube. Using the mist removing device arranged in the provided cylindrical body, the same aerosol as above was introduced into the inflow pipe under the same conditions, and the collection performance of the device was evaluated in the same cycle as above. The obtained results are shown in Table 1.

[0038]

[Table 1]

From these results, the mist removing device of the present invention for classifying mist in advance and removing it with a coarse-graining filter and an ordinary filter, etc. is compared with a device for removing mist with a coarse-graining filter etc. without classifying it. Thus, it can be seen that the collection efficiency and the pressure loss change little over time, and the life is long.

[0040]

According to the mist removing device of the present invention, all the mists can be efficiently separated and removed from the mist-containing gas containing the mist of various particle sizes. Moreover, the mist removing device of the present invention is unlikely to cause clogging even when the flow of the mist-containing gas is intermittent, and can be used for a long period of time.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing a specific example of a mist removing device according to the present invention.

FIG. 2 is a schematic front view showing a specific example of a coarse-graining filter used in the mist removing device of the present invention.

FIG. 3 is a schematic cross-sectional view of a device for explaining a classification action by the mist removing device of the present invention.

FIG. 4 is a graph showing a distribution of mist particle diameters before and after classification by the apparatus of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Inflow pipe 2 1st flow path pipe 3 2nd flow path pipe 4 Slit 5 Airtight chamber 6 Cylindrical body 7 Baffle plate 8 1st filter 9 2nd filter 10 Baffle plate 11 Suction pipe 12 Nylon monofilament 13 Filiform support material 14 Frame

Claims (5)

[Claims] 1. An airtight chamber provided with an inflow pipe for a gas flow of mist-containing gas, and a first flow path pipe having an axial center line aligned with that of the inflow pipe and having an inlet opening in the airtight chamber at a slit interval from the inflow pipe outlet. A baffle plate provided in the first flow path pipe and a first filter provided downstream of the baffle plate, a second flow path pipe having an inlet opening into an airtight chamber, and the first filter provided in the second flow path pipe And a second filter having a smaller pressure loss than the above filter. 2. The second filter is composed of a plurality of single fibers or fiber yarns arranged substantially parallel to each other in a longitudinal direction and spaced from each other, and collects mist in a gas to coarsen the particles. The mist removing device according to claim 1, wherein the mist removing device is a coarse particle filter that re-disperses in a gas as coarse particle mist or droplets. 3. A plurality of monofilaments or fiber threads of the coarse-graining filter are arranged in a comb shape in a plane parallel to the length direction and at intervals from each other, and are fixed at both ends thereof, respectively. The mist according to claim 2, wherein the mist is fixed and both ends are released by a thread-shaped support material composed of single fibers or fiber threads arranged in a direction substantially perpendicular to each single fiber or fiber thread. Removal device. 4. A plurality of the second filters are arranged along the axial direction of the second flow path pipe,
The mist removing device according to claim 1. 5. The mist removing device according to claim 2, wherein the second filter is a coarse-grained filter, and a baffle plate is arranged downstream of the coarse-grained filter. .