JPS5931374B2 - Gas-liquid contact method - Google Patents

Description

[Detailed description of the invention] The present invention relates to a gas-liquid contact method.

More specifically, the present invention relates to a method in which a superficially porous hollow fiber is used to separate gas components by absorption or chemical reaction through contact between a liquid phase and a gas phase.

A method for separating a specific component gas from a mixed gas or a method for obtaining a gas reaction product is generally an absorption method, and systems such as a packed column, a tray column, a spray column, a wet wall column, and a bubble column are used.

All of these methods involve gas-liquid contact, but each has advantages and disadvantages, and is used industrially depending on the purpose.

The present inventor has further improved these methods and has arrived at the present invention as a result of intensive studies to reduce construction costs, reduce facility area and volume, improve product purity, improve productivity, and simplify repairs. It is something.

In other words, this was made possible by using superficially porous hollow fibers in order to maintain a large capacity coefficient of the liquid phase and improve the contact efficiency between the gas and the liquid phase.

That is, the present invention maintains the surface of a porous hollow fiber in contact with a solvent, and allows the mixed gas to be treated to permeate from the inside of the hollow fiber to the outside, so that a specific component in the mixed gas to be treated can be absorbed into the solvent. This is a gas-liquid contact method characterized in that the remaining components are collected or released by absorption with the solvent or reaction with the solvent.

The use of hollow fibers in accordance with the method of the present invention provides an increased surface area/volume ratio compared to conventional fillers such as Raschig rings, and significantly reduces weight and equipment costs.

In addition, it is easy to control the size and size of the device.

The quality of the treated gas is determined by the fact that the gas passes from the inside of the hollow fiber to the outside, which also serves as a filter, and impurities in the gas are completely removed to obtain a high-purity product. It becomes possible.

The porous hollow fibers used in the present invention include polyethylene, polypropylene, polyac IJ O nitrile, polyester, polybutylene terephthalate, fluorine-based vinyl polymers such as Teflon, nylon, aromatic polyamide, polysulfone, and other commercially available synthetic fiber raw materials. Manufactured using

The hollow fibers can be made porous by a method such as stretching heat treatment as described in Japanese Patent Application No. 110996/1982,
No. 135171, a method is known in which one component is dissolved and removed from a hollow fiber obtained by a coagulation method or a blending method.

Hollow fibers without pores or hollow fibers with an active layer with ultrafine pores used as semipermeable membranes can be used in some applications, but their gas permeability coefficients are too low, making them unsuitable for normal applications. , preferably with a gas permeability coefficient of 5
It is economically effective that it is 10-8 crA/crit-sec, mHfi or more.

If the pore size is too large, the liquid will penetrate into the hollow fibers, clogging the fibers, requiring a large amount of pressure to supply air, and causing large leaching of gas, which will cause problems in the liquid phase. Absorption becomes insufficient.

Therefore, the average pore size on the hollow fiber surface is 50A° in terms of diameter.
It is preferable that it is in the range of 5.0 μm from 100 A′ to 10 μm.

The inner diameter of the hollow fiber must have a small pressure loss, and should be 50
The upper limit of the thickness is preferably μ or more, and there is no particular restriction on the upper limit of the thickness, but when considering increasing the surface area within a certain volume, it is not efficient to be too thick, and it is difficult to From the viewpoint of strength as well, it is preferable that the thickness be several milliJ meters.

The hollow fibers can be bundled and bonded using a suitable adhesive and sealed to prevent air leakage.

It is necessary to select materials for the hollow fibers and adhesive that will not be soaked in the solvent of the system used.

The bundled hollow fibers can be directly immersed in the liquid phase, or the liquid phase can be flowed along the surface layer of the hollow fibers, and the permeated gas oozes or blows out from the inside of the hollow fibers to the surface through the small holes. , in contact with the solvent''.

Gas absorption or reaction takes place there, part of the gas being absorbed and the remaining part passing through the liquid phase or space to the outlet.

The gas is extremely purified because the pores on the surface of the hollow fibers are small, so that impurities are filtered out.

Is this gas collected and used for other purposes as necessary?
Or it is released as is.

The solution phase that has absorbed or reacted with components considered to be effective substances or impurities from the gas is taken out of the system through the hollow fibers or from the solution discharge pipe.

The method of the present invention has a large capacity coefficient of the liquid phase and is characterized by being able to obtain a higher concentration than conventional industrial methods.

In this method, since the fibers are thin, the hollow fibers with an outer diameter of 300 microns have a surface area of 900 mj even if the volume filling factor is 30 in a volume of 1 m'.

This value means that the surface area of the filling material per 1rT13 such as Raschig ring is 100 to 300rr? /m'', it can be seen that it is quite large.

Also, the weight of the Rashig ring alone is 400 to 2000.
kg/nT3, but if hollow fiber is used, it is only 1
It only weighs between 00 and 60 kg.

This reduction in weight also simplifies the exterior packaging and significantly reduces the cost of the device.

Hollow fibers are synthetic polymers, so they don't rust like metal and don't break like ceramic or glass Raschig rings.

In addition, it can be handled by disposing of it as appropriate, making it safe for work and easy to handle.

Regarding productivity, it has a surface area of 900 m and a gas permeability coefficient of 5 x 10-” crJ,/cytt-sec,
Using the H& hollow fiber filled device, approximately 300 m'/hr of permeate gas can be processed at 3 atmospheres.

The method of the present invention includes a method for recovering alcohols such as ethanol and methanol from a gas containing vapor, a method for removing alcohol from a gas containing ammonia, hydrogen sulfide,
Methods for removing or recovering these components from sulfur compounds such as sulfur dioxide, methods for absorbing oxygen in the air into solvents, methods for removing these components from gases containing nitrogen oxides, acetone, low-molecular hydrocarbons, etc. Gases containing organic compounds are effectively used as a gas-liquid contact method in methods for removing or recovering these compounds.

The details will be explained below using examples, but the scope of the present invention should not be limited by the examples.

Example 1 A polypropylene hollow fiber having minute holes penetrating the hollow fiber surface and inner surface was prepared, the fibers were bundled, both ends were bound together with an epoxy adhesive, and the fibers were placed in a container as shown in FIG. 1.

The gas permeability coefficient of this polypropylene hollow fiber in water is 5.3 x 10-8 (J/cr?t ・5ec-cr
It was rtH&.

The total surface area of the hollow fibers is 20 m'.

This device was used to recover ethanol with water from CO2 gas containing ethanol vapor emitted from the ethanol production process by precision fermentation, and to reuse the recovered cotanol aqueous solution for fermentation.

When CO2 gas containing 0.8 molar ethanol vapor was supplied into water at a rate of 30 m'/hr and treated using this method, ethanol was completely recovered.

An aqueous ethanol solution was obtained from the solution recovery port, the amount of recovered ethanol was approximately Q, 5 kg/h, and the ethanol concentration in the aqueous solution was 5% on average.

Example 2 A device similar to that used in Example 1 was used for the purpose of removing NH3 in the air by absorbing it into water. Air was fed at 1 atm and 10 lT13/hr was processed.

Water was allowed to flow along the sides of the hollow fibers at a rate of 10 kg/hr.

This completely removed NH3 from the air.

The gas pressure drop was almost ignored because the thickness of water flowing on the fiber surface was small.

Example 3 Using the same apparatus as used in Example 1, a gas containing hydrogen sulfide was treated.

Using an alkaline aqueous solution as the solvent, it was found that almost no hydrogen sulfide was present in the recovered gas.

No damage was observed to the polypropylene hollow fibers even after prolonged contact with the alkaline aqueous solution.

[Brief explanation of the drawing]

The drawing shows a perspective cross-sectional view of an example of an apparatus for carrying out the invention. 1... Raw material gas supply port, 2... Hollow fiber, 3... Solvent inlet, 4... Recovery gas outlet, 5...・Collected solution outlet, 6...
·container.

Claims (1)

[Claims] 1. A gas-liquid contact method characterized by keeping the surface of a porous hollow fiber in contact with a solvent and supplying and permeating a gas from the inside of the hollow fiber to the outside. 2 Claims characterized in that a mixed gas containing multiple components is used as a supply gas, a specific component in the mixed gas is absorbed into a solvent or reacted with the solvent, and the remaining gas is collected or released. The method described in paragraph 1. 43 Gas permeability coefficient as porous hollow fiber is 5×1
The method according to claim 1 or 2, characterized in that 0-8 crA/cri·sec, cmH9 or more is used. 4 Using gas containing alcohol vapor as the supply gas,
The method according to claim 1, 2 or 3, characterized in that water is used as a solvent. 5 Claim 1 characterized in that a gas containing ammonia is used as the supply gas and water is used as the solvent.
3. The method described in Section 2, Section 2, or Section 3. 6. The method according to claim 1, 2 or 3, characterized in that a gas containing a sulfur compound is used as the supply gas and a liquid containing a component reactive with the sulfur compound is used as the solvent. 7. The method according to claim 1, 2 or 3, characterized in that air is used as the feed gas and oxygen is absorbed into the solvent.