JPH07144104A - Continuous deaerator - Google Patents

Abstract

PURPOSE:To perform deaeration treatment with high precison by providing a bottom plate and a top plate of a rotor with impact plates and giving multiple impact to liquid contg. bubbles, particularly emulsion. CONSTITUTION:Liquid contg. bubbles is fed from a feeding nozzle 1 to the central part of a rotor in a vacuum or evacuated vessel 7. Then, the liquid is accelerated by centrifugal force caused by the rotation of the rotor and moved from the central part to the centrifugal part on the bottom plate 2 of the rotor. Next, the liquid hits against a lower impact plate 3a having the shape of an inverted turncated cone of the bottom plate 2 and is further accelerated along the inner surface and is jetted. After the liquid hits against an upper impact plate 6a having the shape of a turncated cone of the top plate 5 supported by a supporting piece 4 of the bottom plate 2, it is further accelerated along the inner surface and is jetted. The liquid is transferred to impact plates 3b, 6b, 3c having lager peripheral velocity in order. After the impact, acceleration and jetting are repeated, the liquid is made to fall on the inner wall of the vessel 7 and deaerated.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a continuous defoamer for improved bubble-containing liquids, especially emulsions. Specifically, by allowing the bubble-containing liquid to pass through the rotating body having a specific structure in a vacuumed or depressurized container, it is possible to continuously and highly accurately crush and erase the bubbles in the bubble-containing liquid. The present invention relates to a defoaming device.

[0002]

2. Description of the Related Art Various liquids, especially various emulsions, are widely used in various industries such as rubber industry, coating industry, adhesive industry, etc. The air bubbles dispersed in them cause various troubles. For example,
Air bubbles contained in the pressure-fed emulsion cause cavitation and erosion of the pump and system parts, and also cause an increase in filling volume due to a decrease in liquid specific gravity. Air bubbles contained in the adhesive emulsion used for adhesive labels and tapes also cause uneven coating. On the other hand, these emulsions always have a transfer process, a stirring process, and the like in the manufacturing process, and gas is entrained in this process. This gas floats and breaks bubbles when the emulsion has a low viscosity, but it is difficult to float at medium and high viscosities and remains in the emulsion, which causes the above-mentioned troubles.

On the other hand, many emulsions have insufficient mechanical stability such that they have a property of forming a film when water content evaporates, form a lump by stirring, or break the emulsion, and thus defoam. Makes it difficult to mechanically process. Therefore, when defoaming an emulsion having many bubbles, a batch treatment has been mainly adopted in which defoaming is performed for a long time while gently stirring in a stirring tank under vacuum or reduced pressure.

Further, as a method for continuously degassing bubbles in a handling liquid with high accuracy, a method using a bottomed sieve which rotates in a vacuum container has been proposed.
For example, one proposal is made in Japanese Patent Publication No. 2-12121.

However, in the method using a bottomed sieve which rotates in a vacuum container, when an emulsion having a high film-forming property or an emulsion having insufficient mechanical stability is treated, the fixing plate and the fixing plate of the sieve are fixed. Since the cylindrical body erected on the stand is stationary, there is a part where the emulsion adheres locally and is difficult to renew, and the emulsion that adheres to that part evaporates water over time to form a deposit. In addition, due to the strong shearing force applied when the emulsion passes through the pores of the cylindrical screen, lumps are generated or the emulsion is partially broken, which makes it easier for these deposits to grow. In a short period of time, the bottom plate of the sieve, the cylindrical screen erected on the bottom plate, the fixed plate and the liquid contact part of the cylindrical body erected on the fixed plate generate an emulsion film or a deposit such as a lump. Fine grow, the pores of the screen is closed by the deposits, defoaming is significantly inhibited as a result. Further, in a cylindrical screen that has been once blocked by these deposits, it is possible to completely remove the deposits by washing and to recover the pores while installing it in the container unless there is a cleaning liquid that can dissolve the deposits. Although it is difficult to remove the deposits by mechanical cleaning such as jetting, it is necessary to stop the operation each time for cleaning, and in order to improve the accuracy of defoaming, the sieve The more complicated the structure of, the more difficult it is to deal with mechanical cleaning of the bottom plate that constitutes the sieve body, the cylindrical screen that is erected on the bottom plate, the fixed plate, and the cylindrical body that is erected on the fixed plate. It also has drawbacks. Furthermore, the emulsion dispersed in the sieving body blows out from the through holes of the fixed plate provided to discharge the degassed gas, and the adhered matter is generated and grows up to the part in the container that does not normally come into contact with the liquid. That's how problems can occur.

As described above, an emulsion film or agglomerate is unlikely to adhere to an emulsion having a high film-forming property or an emulsion having insufficient mechanical stability. A continuous defoaming device using a rotating body that exhibits accurate defoaming performance has not yet been established, and there is a great demand for it.

[0007]

DISCLOSURE OF THE INVENTION The present invention provides various bubble-containing liquids, in particular, emulsions rich in film-forming property or emulsions having insufficient mechanical stability, in which films or lumps of these emulsions adhere. (EN) Provided is a continuous defoaming device using a rotating body which is difficult and does not deteriorate the defoaming performance even when adhered, and which exhibits a highly accurate defoaming performance.

[0008]

In view of the above circumstances, the present inventors have conducted intensive studies on a continuous defoaming device for a liquid containing bubbles, and as a result, completed the present invention.

That is, according to the present invention, a disk-shaped bottom plate having a concentric lower collision plate provided upright or inclined to the circumferential side, and a lower plate colliding with the lower collision plate, and depending on the drooping or circumference. Has a concentric upper collision plate inclined to the side, and accommodates a hollow disc-shaped rotating body composed of a top plate supported by the bottom plate, and a central portion of the disc-shaped rotating body. The present invention relates to a continuous defoaming device comprising a decompression container equipped with a pipeline for supplying a liquid containing bubbles and a decompression means.

By using the apparatus of the present invention, it becomes possible to continuously and highly accurately crush and erase bubbles in a liquid containing bubbles, particularly bubbles in an emulsion as follows. That is, a bottom plate having a concentric lower collision plate that rotates in the decompression container and is provided upright or inclined toward the circumference, and a bottom plate that is supported by the bottom plate and that is positioned alternately with the lower collision plate and droops or circles. The bubble-containing liquid supplied to the central portion of the hollow disk-shaped rotating body composed of the top plate having the concentric upper collision plate inclined to the circumferential side, is superposed on a plurality of collision plates by centrifugal force. Bubbles existing in the liquid when collided are destroyed and erased.

The present invention will be described in more detail with reference to the drawings. FIG. 1 shows an embodiment of the device of the present invention. 1 shown in FIG. 1 is a supply line (nozzle) for a liquid containing bubbles, 2 is a disc-shaped bottom plate, 5 is a top plate, and 3a to 3c are circumferential sides of the disc provided on the bottom plate. 6a to 6c, each of which is a lower collision plate that is inclined to the bottom, and each of the collision plates has an inverted truncated cone-shaped structure as a whole.
Is also an upper collision plate provided on the top plate. Reference numeral 4 denotes a support piece for supporting and fixing the top plate with the bottom plate. The entire hollow disk-shaped rotating body formed by the top plate and the bottom plate is housed in a container 7 capable of vacuuming or decompressing and an external driving body. It is connected.

Continuous defoaming using this apparatus is performed as follows. The liquid containing bubbles supplied to the center of the rotating body installed in the vacuum or decompression container 7 by the supply nozzle 1 is accelerated by the centrifugal force generated by the rotation of the rotating body, and the liquid on the bottom plate 2 of the rotating body is accelerated. Move from the center to the centrifuge. Then, it collides with a lower collision plate 3a having an inverted truncated cone shape erected on the bottom plate 2 and is further accelerated and ejected along the inner surface of the collision plate 3a. Furthermore, this jetted liquid is the bottom plate 2
The upper collision plate 6a, which is erected on the top plate 5 supported by the support piece 4, is collided with the upper collision plate 6a, and further accelerated along the inner surface of the collision plate 6a to be ejected. Further, the liquid is sequentially transferred to the collision plates 3b, 6b and 3c having a higher peripheral speed, and collision, acceleration and ejection are repeatedly performed in the same process as described above, and finally ejected from the outermost upper collision plate 6c, It collides with the inner wall of the vacuum or reduced pressure container 7 and flows down, and finally accumulates in the lower part of the container and is appropriately extracted. The above operation, that is, the liquid containing bubbles is caused to collide multiple collision plates by centrifugal force,
Highly accurate defoaming can be realized by finally allowing the inner wall of the container to flow down.

The installation angle of each collision plate with respect to the bottom plate and the top plate,
The number of collision plates installed, the number of revolutions of the rotating body, the degree of vacuum in the container, etc. may be adjusted according to the physical properties such as the viscosity and mechanical stability of the liquid to be treated and the desired degree of defoaming. Defoaming with high precision can be realized. Examples of preferable ranges are as follows, for example.
That is, the installation angle of the collision plate is 50 to 85 °, and the installation number of the collision plate is two or more for each of the top plate and the bottom plate, and the upper limit is limited in terms of manufacturing and driving ability. The ratio to the cross-sectional area is 55 to 80%, the rotational speed of the rotating body is 10 to 80 m / s at the peripheral speed, the pressure in the container is 100 mmHg or less, but not less than the saturated vapor pressure of water at the temperature during operation.

The material of each part of this apparatus may be set arbitrarily in consideration of strength and corrosion resistance, but in order to more thoroughly prevent adhesion, it is preferable that the surface is coated with a fluororesin. . Examples of the fluorine-based resin include tetrafluoroethylene resin, tetrafluoroethylene-perfluoropropyl vinyl ether copolymer, tetrafluoroethylene-6 fluoropropylene copolymer, trifluoride monochloride ethylene resin, ethylene- Examples thereof include tetrafluoroethylene copolymer.

The shape and number of the support pieces for supporting and fixing the top plate with the bottom plate are not particularly limited, and may be set so that the dynamic balance during rotation can be secured. Further, as in the above, it is preferable that the surface thereof is coated with a fluororesin.

In order to further improve the defoaming effect, the bubble-containing liquid before being supplied to the rotating body in the present invention is exposed to an atmosphere kept under vacuum or reduced pressure to further expand the bubbles in the liquid. It is preferable that a pretreatment bath for that purpose is also installed. Generally, it can be said that the larger the bubble diameter than the thin film thickness of the liquid formed by the rotation of the rotating body or the flow down on the inner wall of the container, the easier it is for the bubbles to break. Since the bubbles partially expand and greatly expand the fine bubbles, the bubbles in the liquid are more easily broken in the rotating body and the inner wall of the container in the present apparatus.

A pump is installed below the decompression container 7,
By discharging the liquid flowing down the inner wall of the container, the defoamed liquid can be continuously taken out to the outside of the container with desired accuracy. Here, continuous does not mean that it is strictly steady, and it does not matter in the present invention whether the discharge amount is pulsed or intermittently discharged.

[0018]

[Function] Conventionally, bubbles in the handling liquid expanded under vacuum or reduced pressure are shredded and broken by the shearing force applied when passing through a screen having pores. Although it was considered to be an important factor for realizing the structure, the rotating body of the present invention does not have such a screen structure at all, and the collision plate provided on the bottom plate 2 and the top plate 7 of the rotating body is used. High-precision defoaming is realized by making multiple collisions of liquid containing bubbles, especially emulsion. In addition, since the rotating body in this device does not have a screen structure, solid matters originally contained in the emulsion and deposits such as emulsion coatings and lumps which are particularly problematic when processing the emulsion in the rotating body. Since there is no part that causes blockage, there is no possibility that the defoaming performance will be deteriorated due to the adhered substances as in the case of a screen body having a screen structure.

Further, the top plate 5 of the rotary body and the upper collision plates 6a to 6c standing on the top plate 5 in this apparatus are not fixed, but are supported by the support piece 4 rather than the bottom plate 2 of the rotary body. It is supported at a plurality of points and therefore rotates together with the bottom plate 2 of the rotating body. As a result, all the bubble-containing liquid contacting the top plate 5 and the upper collision plates 6a to 6c erected on the top plate 5 is moved and accelerated from the central part toward the centrifugal part by the centrifugal force. In addition to the further improvement of the defoaming effect, the water content of the top plate 5 and the upper collision plates 6a to 6c standing on the top plate 5 and the like, especially the water content of the emulsion, may be removed with time. Evaporating to generate the deposits is compared with the case where the top plate and the collision plate standing on the top plate are fixed and stationary, for example, when the sieve body described in Japanese Patent Publication No. 2121121 is used. And extremely less.

Further, the top plate 5 of the rotating body in the present apparatus
Does not need to have a through hole for discharging the degassed gas. The through hole causes a problem that the liquid dispersed in the rotating body blows out from the through hole and an adhered matter is generated and grows up to a portion in the container that is not normally in contact with the liquid. In this case, highly accurate defoaming can be realized without providing the through hole, and there is no particular need to install the through hole.

As described above, the apparatus of the present invention enables the operation in which the bubble-containing liquid is caused to collide with a plurality of collision plates by a centrifugal force under a reduced pressure, and further the inner wall of the reduced pressure vessel is caused to flow down. It has the effect of effectively eliminating bubbles in various liquids, especially emulsions.

[0022]

EXAMPLES The present invention will be described in more detail below by taking defoaming operations using this apparatus as examples, together with comparative examples, but the present invention is not limited to these examples.

The average number of bubbles / the average number of remaining bubbles in the emulsions described in these examples is a value measured by the following test method. Average Number of Bubbles in Emulsion / Average Number of Remaining Bubbles The emulsion to be measured is about 90 mm wide with a baker applicator so that the thickness is 1 mm on a transparent film.
Extend the length to about 250 mm. Two of these are prepared and naturally dried for one day. The naturally dried emulsion changes from milky white to transparent, but the transparent film has a width of 75 mm and a length of 2
Bubbles that can be visually confirmed in the range of 00 mm were counted, and the two counted values were arithmetically averaged to obtain the average number of bubbles / average number of remaining bubbles in the emulsion.

Example 1 A flask equipped with a stirrer, a thermometer, a condenser and two dropping funnels was charged with 30 parts of water and heated to 80 ° C. 59 parts of 2-ethylhexyl acrylate, acrylonitrile 3 prepared in advance
Parts, 2 parts of methyl methacrylate, and 2 parts of methacrylic acid were added as an emulsifier with 4 parts of sodium polyoxyethylene nonylphenyl ether sulfate, and the resulting monomer emulsion was emulsified with a 25% ammonium persulfate aqueous solution. Two parts were evenly dropped into the flask by the dropping funnel for 4 hours to carry out polymerization. After completion of dropping, 1
After adding 1 part of 3% ammonium persulfate and further aging at 80 ° C. for 2 hours to complete the polymerization, an antiseptic agent and an antifoaming agent were added after cooling to obtain an emulsion of an acrylic copolymer having a viscosity of 2000 cps.

Next, this acrylic copolymer emulsion was defoamed according to the flow sheet shown in FIG. First, the emulsion is charged in the tank 10, and the inside of the flow-down pipe 12 and the continuous defoaming device 13 is sucked by the vacuum pump 15 to adjust the pressure to 25 mmHg, and the rotating body installed in the continuous defoaming device 13 is rotated at the peripheral speed. Is rotated at a rate of 40 m / s, the emulsion is supplied at a flow rate of 160 kg / hr from the tank 10 by using the supply pump 11, while maintaining the liquid level in the continuous defoaming device 13 constant. A product that was continuously extracted from the extraction pump 14 was obtained.
The average number of bubbles in the emulsion supplied at this time was 123. Further, in the apparatus shown in FIG. 3, the downflow tube 3 uses a stainless steel tube having an inner diameter of 83.1 mm and a length of 500 mm, and the rotating body installed in the continuous defoaming apparatus 13 has a structure. As shown in Fig. 1, the bottom plate diameter is 360 mm, which is coated with tetrafluoroethylene-perfluoropropyl vinyl ether copolymer on the entire surface. The bottom plate and the top plate are supported and fixed with 6 support pieces at intervals of 30 mm. I used the one that was used. The average number of remaining bubbles of this treated product is shown in Table 1.

Example 2 Emulsion supply flow rate was 1
A treated product was obtained in the same manner as in Example 1 except that the amount was set to 06 kg / hr. The average number of bubbles in the emulsion supplied at this time was 112, and the average number of remaining bubbles in the treated product is shown in Table 1.

[Embodiment 3] The supply flow rate of the emulsion is 2
A treated product was obtained in the same manner as in Example 1 except that the rate was 10 kg / hr. The average number of bubbles in the emulsion supplied at this time was 115, and the average number of remaining bubbles in the treated product is shown in Table 1.

[Example 4] A processed product was obtained in the same manner as in Example 1 except that the peripheral speed of the rotating body installed in the continuous defoaming device 13 was set to 30 m / s. The average number of bubbles in the emulsion supplied at this time was 131, and the average number of remaining bubbles in the treated product is shown in Table 1.

[Embodiment 5] A treated product was obtained in the same manner as in Embodiment 1 except that the peripheral speed of the rotary member installed in the continuous defoaming device 13 was set to 50 m / s. The average number of bubbles in the emulsion supplied at this time was 130, and the average number of remaining bubbles in the treated product is shown in Table 1.

Example 6 A processed product was obtained in the same manner as in Example 1 except that the emulsion was directly supplied to the continuous defoaming device 13 without passing through the flow-down pipe 12. The average number of bubbles in the emulsion supplied at this time was 125,
The average number of remaining bubbles in the treated product is shown in Table 1.

[Comparative Example 1] The structure of the rotating body installed in the continuous defoaming apparatus 13 was such that a cylindrical screen having a pore diameter of 1.5 mm was erected on the bottom plate as shown in FIG. The same process as in Example 1 was carried out except that the treated product was obtained before the pores of the cylindrical screen were clogged with deposits.
The average number of bubbles in the emulsion supplied at this time was 107. Also, after about 30 minutes from the start of supplying the emulsion, most of the pores of the cylindrical screen came to be blocked. The average number of remaining bubbles of this treated product is shown in Table 1.

[Comparative Example 2] The same procedure as in Example 1 was conducted except that the treated product was obtained after the pores of the cylindrical screen were clogged with deposits in Comparative Example 1, and the average number of remaining bubbles was determined. It was shown to. The average number of bubbles in the emulsion supplied at this time was 114. Similar to Comparative Example 1, almost 30 minutes after the start of feeding the emulsion, most of the pores of the cylindrical screen were closed.

[0033]

[Table 1]

[0034]

INDUSTRIAL APPLICABILITY According to the present invention, it is difficult for an emulsion film or lump to adhere to various bubble-containing liquids, particularly emulsions having a high film-forming property or emulsions having insufficient mechanical stability, and even if they adhere, they may be removed. It is possible to perform a highly accurate defoaming process without lowering the foaming performance.

[Brief description of drawings]

FIG. 1 is a side sectional view of a continuous defoaming apparatus which is an embodiment of the present invention.

FIG. 2 is a side sectional view of a conventional continuous defoaming device.

FIG. 3 is a flow sheet of a continuous defoaming system using the device of the present invention.

[Explanation of symbols]

 1 ... Supply nozzle 2 ... Bottom plate 3a-3c ... Lower collision plate 4 ... Support piece 5 ... Top plate 6a-6c ... Upper collision plate 7 ... Decompression container 8 Fixed top 9 Cylindrical screen 10 Tank 11 Supply pump 12 Downflow pipe 13 Continuous removal Bubble device 14 ・ ・ ・ ・ Extraction pump 15 ・ ・ ・ ・ ・ ・ Vacuum pump 16 ・ ・ ・ ・ Liquid level gauge 17 ・ ・ ・ ・ Inverter 18 ・ ・ ・ ・ ・ ・ Vacuum gauge

Claims (1)

[Claims] 1. A disk-shaped bottom plate having concentric lower collision plates provided upright or inclined toward the circumferential side, and alternated with the lower collision plates and slanted toward the circumferential side. Has a concentric upper collision plate provided therein, and accommodates a hollow disk-shaped rotating body composed of a top plate supported by the bottom plate, and a bubble-containing liquid to the center of the disk-shaped rotating body. A continuous defoaming device, which comprises a decompression container equipped with a pipeline for supplying air and a decompression means.