JPS6048104A - Defoaming process and apparatus - Google Patents

Abstract

PURPOSE:To remove bubbles contained in liquid through a pipe wall with high efficiency while the liquid is passed through the pipe by using a pipe comprising a gas permeable porous material but impermeable to the liquid to be passed. CONSTITUTION:Liquid 4 contg. fine bubbles is fed through a liquid transporting pipe 1 at an inlet side. The liquid 4 passes a defoaming section comprising a gas permeable porous pipe 2 for defoaming. In this stage, a throttling device 7 attached to the top of a liquid transporting pipe 3 at the outlet side is adjusted to provide a flow rate necessary for defoaming. Bubbles in the liquid are removed through gas permeating pores in the pipe wall of the gas permeable porous pipe 2 while the liquid passes through the defoaming section, and defoamed liquid 5 is transferred to the next stage through the liquid transporting pipe 3 at the outlet side. Drawn porous polytetrafluoroethylene is preferred as the material for the gas permeable porous body.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a defoaming device that efficiently removes air bubbles contained in a liquid, particularly fine air bubbles that take time and effort to remove, during the process of transporting the liquid through a pipe.

Conventionally, there has been a need to efficiently and sufficiently remove microbubbles in liquids. Examples include injection of a drug solution into a blood vessel, injection of a reagent for liquid chromatography, and delivery of a film stock solution by a casting method. Since the presence of fine bubbles has a large negative effect on these, it is necessary to thoroughly remove them. Although it is possible to remove these microbubbles by allowing the solution to stand still for a long time or by reducing the pressure, it is complicated to perform such a process during the infusion process. Particularly when defoaming is required during a continuous infusion process, it is desirable to remove bubbles efficiently in a short time in the infusion tube. Furthermore, if there is a stirring process or a pump connected in front of the continuous infusion pipe, there is an even greater chance of air bubbles being mixed in, so rapid and efficient defoaming is desired. .

However, until now, there has been no method for sufficiently efficiently removing such air bubbles, particularly during passage through an infusion tube.

The inventors of the present invention have arrived at the present invention as a result of various studies on methods to satisfy such demands.

That is, the present invention uses a tube made of an air-permeable porous material that is impermeable to the target liquid, and removes air bubbles contained in the liquid while the liquid passes through the continuous porous tube. It is removed through the wall of the tube.

In order for any liquid to be impermeable to the breathable porous body, it is necessary that the liquid has a contact angle of 90 degrees or more with respect to the substance constituting the breathable porous body. Examples of such combinations include, when the liquid is water, combinations with polytetrafluoroethylene, polypropylene, polyethylene, etc.

In order for air bubbles to pass through the walls of the infusion tube and be removed from the infusion tube while the liquid is flowing through the infusion tube, the bubble pressure inside the tube made of breathable porous material must be higher than the pressure outside the tube. The larger the pressure difference, the better the efficiency. Therefore, it is also effective to reduce the pressure outside the tube to below atmospheric pressure. Note that if the internal pressure of the tube becomes too high, even a liquid that is originally impermeable to the air-permeable porous body made of this material will eventually permeate through the continuous pores. This critical pressure becomes higher as the continuous pores become smaller. Therefore, the internal pressure of the pipe is increased within a range that does not cause this liquid leakage, the continuous pores of the pipe wall are made large, the porosity of the pipe wall is increased,
Furthermore, the thinner the porous tube wall is, the better the defoaming efficiency becomes. Generally, when the pressure in the infusion tube is low, sufficient pressure may not be obtained for defoaming, but in this case, it is necessary to take measures to increase the pressure in the tube of the defoaming section to the required level. This can be effectively achieved by making the diameter of the outflow pipe from the air-permeable porous defoaming pipe smaller than the diameter of the inflow pipe to the limb canal.

This can also be achieved by tapering the defoaming tube so that it becomes narrower in the direction from the inlet to the outlet of the defoaming liquid. This can also be achieved by attaching a throttling device to the tip of the outflow pipe, thereby adjusting the outflow cross-sectional area of the outflow pipe.

Note that the thinner the breathable porous tube is, the better the defoaming efficiency is, but if it is too thin, there will be problems in terms of strength. In this case, it is desirable to laminate a reinforcing porous layer with almost no ventilation resistance. Further, as for the pipe diameter, a smaller one is preferable from the viewpoint of improving the defoaming efficiency.

Furthermore, when the liquid to be degassed is a solution, the vent holes in the tube wall of the ventilated porous tube for defoaming may become clogged with solute due to evaporation of the solvent during long-term use. There is. In such cases, it is effective to immerse a defoaming section using an air-permeable porous tube in the solvent of the solution to prevent blockage due to solute precipitation.

A typical embodiment of this defoaming device is shown in Figure 1.2.3. The present invention will be described in detail by taking the example shown in FIG. 3 as an example. A bubble-containing liquid 4 containing fine bubbles 6 is sent through the inflow side infusion pipe 1. This passes through a defoaming section consisting of an air-permeable porous defoaming tube 2, but this pressure is adjusted by adjusting the throttle of the throttle device 7 attached to the tip of the outflow side infusion tube 3 to ensure the required flow rate. The level is set to the level required for defoaming.

Thus, while the bubbles in the liquid shell pass through the defoaming section, they are removed to the outside of the tube through the vents in the tube wall of the ventilated porous tube 2 for defoaming.

The bubble removing liquid 5 is thus sent to the next step through the outflow side infusion pipe 3. In FIG. 1, the pressure necessary for the defoaming section is applied using an outflow infusion tube having an inner diameter smaller than that of the inflow infusion tube 1. Further, in FIG. 2, this pressurization is performed using a gas-permeable porous pipe for defoaming which has a taper that becomes gradually thinner in the direction from the inlet to the outlet of the defoaming liquid.

One of the particularly effective breathable porous materials used in this defoaming device is stretched porous polytetrafluoroethylene, which is composed of a large number of nodules 8 and countless fibrils 9 that connect them, as shown in FIG. be. This can be produced, for example, by a method as detailed in Japanese Patent Publication No. 51-18991. This is the contact angle to water of 10
8 degrees and is impermeable to water or aqueous solutions, making it particularly effective for defoaming.

Examples will be described below.

〔Example〕

With the configuration shown in Figure 1, water mixed with microbubbles is transported through 7 recontubes with an inner diameter of 3 tar and an outer diameter of 2, and a stretched porous polytetrafluoroethylene tube with a length of 40++II+1 is placed on the outflow side. Connected. This tube has a structure in which fibrils are arranged in the longitudinal direction, nodes are arranged in the longitudinal direction at right angles to this, and the nodes are connected by many fibrils, and is known as a Voretex tube. The physical properties of this material are as follows.

Inner diameter 2.0 ■ Wall thickness 04 Porosity 50 Invasion pressure 0.9 Ky/cr1 Next, connect a silicone tube with an inner diameter of 0.2 mm and an outer diameter of 2 to the tip of the Vore Tex tube, and The length of the flow path was set to 30 +++ m.

Microbubbles in the water were completely removed while passing through the Voretex tube, and no air bubbles were observed in the water flowing out from the precon tube with an inner diameter of 0.2 mm.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing one embodiment according to the invention. The numbers in the figure are as follows. DESCRIPTION OF SYMBOLS 1...Inflow side infusion pipe, 2...Air permeable porous pipe for defoaming, 3...Outflow side infusion pipe, 4...Bubble-containing liquid, 5...
Air bubble removal liquid, 6. Air bubbles, 7. Squeezing device, 8. Nodules, 9. Fibrils. FIG. 2 is a schematic diagram showing another embodiment according to the present invention. FIG. 3 is a schematic diagram showing another embodiment according to the present invention. FIG. 4 is a diagram showing the fine structure of a stretched porous body of polytetrafluoroethylene suitable for a defoaming tube used in this device.

Claims (1)

[Claims] 1. Using a tube made of an air-permeable porous material that is impermeable to any liquid, the liquid passes through the continuous porous material tube to remove air bubbles contained in the liquid. A defoaming method characterized in that the degassing is carried out through the pipe wall of the pipe. 2. Claim 1, characterized in that the static pressure of the bubble-containing fluid within the air-permeable porous tube for defoaming is configured to be higher than the pressure outside the tube. Defoaming method described in. 3. Claim 1.2, characterized in that the pressure inside the tube is increased by making the diameter of the outflow tube from the air-permeable porous tube for defoaming smaller than the diameter of the inflow tube into the tube. Defoaming method described in. 4. Claim 1.2.3. The breathable porous material constituting the defoaming tube is made of open-pore polytetrafluoroethylene, polypropylene, or polyethylene. An apparatus for carrying out the defoaming method described in . 5. The wall of the defoaming tube is composed of two or more layers, at least one of which is within the scope of claim 1.4, 5.6.
．． Claim 1.2. is a breathable porous body according to claim 1.2, characterized in that the tube wall is breathable as a whole.
3. A device for carrying out the degassing method described.