JPH0478413A - Method and device for separating gaseous mixture - Google Patents

Abstract

PURPOSE:To separate gaseous carbon dioxide and to efficiently transport the carbon dioxide on an industrial scale by providing a heating means capable of making the temp. of the membrane surface layer of the liq. film on the raw gas chamber side lower than the temp. of the membrane surface on the permeated gas chamber side. CONSTITUTION:A gaseous mixture consisting of carbon dioxide, oxygen and the balance nitrogen and kept at room temp. is passed through a raw gas chamber 3, a permeated gas chamber 4 is filled with the gas of the same composition, a valve 7 is closed, a valve 8 is opened, and a tungsten lamp about 10cm from the surface of a light transmission window 2 is turned on. The valve 7 is opened immediately after the lamp is turned off to supply the raw gas to the chamber 4, the gas discharged through the valve 8 while the lamp is turned on is replaced by the raw gas, and the obtained gas is collected. The valve 7 is again closed, the lamp is again turned on, and the process is repeated. Consequently, about 5.7ml of the gas of the same composition contg. almost 52vol.% carbon dioxide is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a mixed gas separation apparatus and method for separating a specific component gas from a mixed gas and actively transporting the separated gas.

[Prior Art] A method of separating a specific component of a mixed gas using a specific separation membrane is gaining ground as an industrial process.

Porous membranes made of glass, inorganic substances such as alumina, and organic polymers such as polyimide and polysulfoshi are known as such separation membranes for mixed gases.

Furthermore, a so-called liquid membrane is also known, which uses an inorganic or organic porous support and a liquid held therein as the separation membrane. Such liquid membranes have a wide range of material selection and are highly selective to the gas to be separated, so they are considered promising as gas separation membranes. For example, a liquid membrane in which a polyhydric alcohol solution of a cobalt dihistidine complex is held on a porous support such as polyethylene has been proposed as a liquid membrane for separating oxygen from a mixed gas of oxygen and nitrogen.
JP-A-1-242124).

[Problems to be Solved by the Invention] The separation of substances using the liquid film is based on the difference in chemical potentials of the substances, and usually the material gas side (
Since the pressure on the permeate gas side (before treatment) is lower than the pressure on the permeate gas side (after treatment), it is necessary to increase the pressure on the raw material gas side or reduce the pressure on the permeate gas side to perform it on an industrial scale. On the other hand, the separation of substances by biological membranes is attracting attention because active transport, which transports substances against the chemical potential, is possible.

Thus, there are great expectations for the realization of industrial-scale separation and active transport of mixed gases. In particular, separation technology is attracting attention because it separates and collects carbon dioxide from waste gas as part of measures to prevent global warming.

An object of the present invention is to provide a mixed gas separation device that makes it possible to separate and actively transport a mixed gas, particularly carbon dioxide gas, on an industrial scale, and a separation method using the separation device.

[Means for Solving Problem 11] The gist of the present invention for achieving the above object is as follows.

(1) A porous support, a liquid membrane formed by holding a liquid in the support, and a raw material gas chamber and a permeated gas chamber separated by the membrane, and a membrane on the raw material gas chamber side of the liquid membrane. A mixed gas separation device characterized in that it is equipped with a heating means that can raise the temperature of the membrane surface layer on the side of the permeated gas chamber higher than the temperature of the surface layer.

(2) It has a porous support, a liquid membrane formed by holding a liquid in the support, a source gas chamber and a permeation gas chamber separated by the membrane, and the gas chamber contains the gas to be separated. A source gas is introduced, and the temperature of the membrane surface layer on the permeate gas chamber side of the liquid membrane is made higher or lower than the temperature of the membrane surface layer on the source gas chamber side, and a specific component of the source gas is separated. Method for separating gas mixtures.

As the porous support for the liquid film, an inorganic material or an organic polymer material is used. Particularly preferred are organic polymer materials such as polyethylene, polypropylene, polytetrafluoroethylene, polyvinylidene fluoride, polyvinyl acetate, or acetyl cellulose. Particularly preferred are those reinforced with metal plates, wire mesh, plastic mesh, or the like.

The liquid held by the porous support is as follows:
In separating carbon dioxide gas, a solution containing alkanolamines such as monoethanolamine and jetanolamine, or an alkali metal carbonate such as potassium carbonate and sodium carbonate can be used. For gases other than carbon dioxide, for example, oxygen, a cobalt complex aqueous solution, especially a fluoramine solution, is selected, and for separation of I(, S), a solution such as 2CO, an aqueous solution, or an alkanolamine aqueous solution is selected.

The concentration of the solution used is 10 to 80% by weight, preferably 10 to 50% by weight.

As the heating means, a heater is provided on the surface of the liquid film on the permeation gas chamber side to heat it. Surplus electricity at night or solar power can be used as energy for the heater. In particular, it is preferable to provide a light transmission window through which light can be irradiated on the surface of the liquid film on the permeation gas chamber side, and to utilize sunlight as thermal energy.

Note that the heater is preferably made of a material that can also be used as a reinforcing member for the porous support.

In addition, in the present invention, in order to actively transport the separated gas, the permeate gas chamber side of the liquid membrane is heated with energy such as sunlight to reduce the interaction between the membrane material on the permeate gas chamber side and the permeate gas. let

However, even if the temperature on the permeate side of the liquid membrane is increased by irradiating the membrane surface on the permeate side with sunlight, the heat is transferred to the source gas chamber side by thermal conduction, and the temperature distribution within the membrane changes over time. homogenization, and the active transport capacity of the separated gas decreases accordingly. As a method for preventing this, when sunlight is used as thermal energy, it can be solved by providing a temperature difference by intermittently irradiating sunlight.

Further, even if the thermal energy is other than light, the object of the present invention can be achieved by periodically applying a temperature difference to both sides of the liquid film.

FIG. 1 shows one embodiment of the present invention.

liquid! l! A light transmitting window 2 is formed on the permeable gas side of the window 2, which can irradiate sunlight as thermal energy.

By intermittently irradiating the light, the separated gas separated by the liquid film can be actively transported to the permeation gas chamber side.

In addition, as shown in the schematic diagram of FIG. 4, a light absorbing agent 9 is dispersed in the liquid film to efficiently perform local heating so that the light energy from the sun or the like is absorbed by the surface layer on the light irradiation side. The efficiency of active transport can be increased by this.

[Effect] The operation of the present invention will be explained with reference to FIGS. 2 to 4.

First, we will explain the mechanism of normal transport (passive transport) based on differences in chemical potential.

In Figure 2, the pressure on the supply side of the transport component A of the liquid film 1 is expressed as (PA
)s and the concentration on the supply side is (CA)s, the following equation (1) generally holds between them.

(PA)fi = (H)fi X (CA)g ・
(1) Here, (HL is a coefficient that relates the two.

When the values of (PA)i and (CA)s are small, they are not affected much and can be treated as constants.

Also, even if it cannot be treated as a constant, it is generally a positive value,
As (pA)g increases, (CA)s also increases.

Similarly, if the pressure on the permeate side of transport component A is (FA)T and the concentration on the permeate side is (CA), r, then the following equation (2) holds between them.

(PA)T = (H)rX (CART...
(2) Here, if the material and temperature of the liquid film are the same, there is no big mistake in thinking that (H)g = (H)T.

Therefore, in the case of (CA)s〉(CA)T, substance A is liquid due to the concentration difference! It passes from the feed side to the permeate side via III. That is, membrane separation of substance A is performed.

However, due to the above relationship, (PA), ≧(PA)T always exists. That is, the pressure (PA)T on the permeate side of substance A does not exceed the pressure (FA)S on the feed side.

By the way, the magnitude of (H) varies depending on the temperature. The solubility of a gas in a liquid decreases as the temperature increases.

Therefore, (H) increases as the temperature increases, and it becomes possible to make the pressure (PA)T on the permeate side higher than the pressure (PA)s on the supply side.

In FIG. 3, it is second
This is the same as the case shown in the figure.

Now, if the surface layer temperature on the permeation side of the liquid film 1 is made higher than the surface layer temperature on the supply side, (H), < (H)T... (3), (PA)S < (pA), ... (
4) becomes possible.

In FIG. 4, as described above, the light absorbent 9 is dispersed on the surface of the liquid film 1 in order to improve the efficiency of active transport.
Equations (3) and (4) above also hold true.

[Example] The present invention will be explained in detail using an example of separation of carbon dioxide gas in a mixed gas.

[Embodiment 1] FIG. 1 is a cross-sectional view of a membrane separator according to an embodiment of the present invention.

Raw material gas (supply gas) separated into two by liquid membrane l
It consists of a chamber 3 and a permeate gas chamber 4. The raw material gas chamber 3 and the permeate gas chamber 4 have a gas supply duct 5 and a gas discharge duct 6.
and valves 7, 8 are provided. In addition, the permeation gas chamber 4
A glass light transmitting window 2 for irradiating light onto the surface of the liquid film on the side of the permeation gas chamber 4 is provided in the mural portion constituting the wall.

The liquid membrane 1 is an acetylcellulose-based porous membrane (porosity 60
A sheet with an effective area of 200 cm 2 impregnated with a 12% by weight aqueous solution of monoethanolamine is used.

At room temperature, the carbon dioxide concentration in the raw material gas chamber 3 is 12% by volume.
, a mixed gas with an oxygen concentration of 2% by volume and a balance of nitrogen is passed through, the permeation gas chamber 4 is filled with a gas of the same composition, and with the valve 7 closed and the valve 8 open, a gas is passed through the surface of the light transmission window 2. 10c
A 400W tungsten lamp placed at position m was turned on for 20 seconds.

When the gas discharged through the valve 8 while the lights were on and the gas obtained by opening the valve 7 and supplying the raw material gas to the permeation gas chamber 4 immediately after the lights were turned off were collected, the carbon dioxide concentration was 5.
5.7me of 2% by volume gas was obtained.

The valve 7 was closed again, the lamp was turned on again 40 seconds after it was turned off, and the same operation as above was repeated to obtain a gas having the same composition and a carbon dioxide concentration of 52% by volume and a volume of 5.7 mA.

By repeating the above-mentioned turning on and off and the accompanying opening and closing operations of the valves 7 and 8, a gas with a high carbon dioxide concentration having approximately the same composition and volume was obtained.

[Embodiment 2] FIG. 5 is a sectional view of a separation device according to another embodiment of the present invention.

The difference from FIG. 1 is that the light transmitting window 2 is arranged close to the liquid film 1.

The source gas chamber 3 is provided with a duct 5 for gas supply and a duct 6 for gas discharge, and the light transmission window 2 is provided with a duct 6 for discharge of transmitted gas.

The liquid membrane was the same acetyl cellulose porous membrane (porosity 60%) as in Example 1, and monoethanolamine 12
A sheet with an effective area of 200 cm 2 impregnated with a wt % aqueous solution was attached.

Furthermore, as in Example 1, the raw material gas chamber 3 at room temperature
Carbon dioxide concentration 12% by volume, oxygen concentration 2% by volume 5 remaining I!
A mixed gas having a composition of iS nitrogen was circulated, and a 400W tungsten lamp provided at a position 10 cm from the surface of the light transmission window 2 was turned on for 20 seconds. When the light is on, the light transmitting window 2
When the gas discharged through the permeated gas discharge duct 6 installed in the
Met.

After 20 seconds, the lamp was turned on again for 20 seconds, and the same operation was repeated to obtain gas of the same composition and volume, with a carbon dioxide concentration of 95% by volume and a volume of 5 ml.

By repeating turning on and turning off the tungsten lamp, gas having approximately the same high carbon dioxide concentration was obtained.

[Example 3] Separation operation was performed using sunlight instead of the tungsten lamp as a light source 6. The separation membrane, separation device, and supplied raw material gas composition were the same as in Example 2.

By irradiating sunlight near midday on a clear day at a right angle for 75 seconds through the light-transmitting window 2, the carbon dioxide concentration was 93% by volume.
, a gas with a high carbon dioxide concentration and a volume of 5.1 mN was obtained.

After repeating 75 seconds of irradiation and 30 seconds of non-irradiation,
During irradiation, a gas with approximately the same carbon dioxide concentration as above was obtained.

[Example 4] An effective area of 200 cm was obtained by impregnating an acetylcellulose-based porous membrane (porosity 60%) with a 121% aqueous solution of monoethanolamine and 31% by mass of charcoal powder dispersed therein.
m'' sheet was used as a liquid membrane, and the separation device and the composition of the supplied raw material gas were the same as in Example 3.

By irradiating sunlight near solar midpoint on a clear day for 50 seconds at a nearly right angle through the light-transmitting window 2, a carbon dioxide gas concentration of 94% by volume and a volume of 5.
．． 1mj! Gas with high carbon dioxide concentration was obtained.

Irradiation for 50 seconds and non-irradiation for 30 seconds were repeated, and during irradiation, a gas with almost the same high carbon dioxide concentration and volume as above was obtained.

[Example 5] A polypropylene porous membrane (porosity 70%) was used as the liquid membrane.
, film thickness 0.15 nm) was treated with methanol to make it hydrophilic,
A sheet with an effective area of 200 cm'' impregnated with a 20% by weight aqueous solution of jetanolamine was attached to the separation apparatus shown in FIG.

As in Example 3, gas having a carbon dioxide concentration of 12% by volume, oxygen concentration of 2% by volume, and the balance being nitrogen was passed through the raw material gas chamber 3 at room temperature, and sunlight near mid-sunlight on a clear day was transmitted. 97% carbon dioxide by volume by irradiating the window at right angles for 75 seconds
, volume 14.4mj! Gas with high carbon dioxide concentration was obtained.

Irradiation for 75 seconds and non-irradiation for 30 seconds were repeated, and during irradiation, a gas with almost the same high carbon dioxide concentration as above was obtained.

Next, another specific example of the mixed gas separation device of the present invention will be described in the sixth section.
- Shown in Figure 9.

FIGS. 6 and 7 show reinforcement members 11° 11' of the liquid film.
This is a separation device that uses diagonal mesh made of polypropylene.

Further, in FIG. 8, a wire mesh is used as a reinforcing member 11 on the side of the permeated gas chamber, and a part of the wire mesh is exposed outside the gas chamber to also serve as a heat radiation fin. This makes it easier to control the temperature of the surface layer of the liquid membrane 1 on the side of the permeated gas chamber, thereby increasing the active transport efficiency of the separated gas.

Furthermore, FIG. 9 shows a case where a polytetrafluoroethylene (PTFE) based polymer porous membrane is used as the porous support of the liquid membrane 1.

Since the PTFE membrane cannot be impregnated with an aqueous solution, a liquid membrane is formed by providing a space capable of holding an aqueous solution between the two liquid holding sheets [113].

[Effects of the Invention] According to the present invention, a mixed gas separation device capable of actively transporting separated gas can be provided. In particular, it is extremely economical because it can use energy such as sunlight and surplus electricity at night as energy for active transportation.

Further, the mixed gas separation device of the present invention is particularly effective for selective separation and active transport of carbon dioxide gas.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view of a separation device of the present invention, FIGS. 2 to 4 are diagrams of the principle of separation phenomenon, and FIGS. 5 to 9 are schematic sectional views of other separation devices of the present invention.

Claims (1)

[Scope of Claims] 1. A porous support, a liquid membrane formed by holding a liquid in the support, and a raw material gas chamber and a permeable gas chamber separated by the membrane; A mixed gas separation device characterized in that it is equipped with a heating means that can raise the temperature of the membrane surface layer on the permeate gas chamber side higher than the temperature of the membrane surface layer on the gas chamber side. 2. The mixed gas separation device according to claim 1, wherein the liquid membrane has a porous support made of an organic polymer material and a reinforcing member having ventilation holes for reinforcing the support. 3. The mixed gas separation apparatus according to claim 1, wherein a heating element is provided on the side of the permeated gas chamber as the heating means. 4. The mixed gas separation device according to claim 3, wherein the heating element also serves as the reinforcing member. 5. The mixture according to claim 1, wherein the heating means is provided with a light transmitting window formed of a light transmitting material so as to irradiate the surface of the liquid film on the permeation gas chamber side with light energy. Gas separation equipment. 6. A light absorbing agent is contained in the surface layer of the liquid film on the permeation gas chamber side, and the liquid film is formed of a light-transmitting material on the permeation gas chamber side so that light energy for heating the surface layer can be irradiated. 2. The mixed gas separation device according to claim 1, further comprising a light transmitting window. 7. The gas mixture according to claim 1, wherein the liquid held in the porous support of the liquid film is selected from an alkanolamine solution or an alkali metal carbonate solution. Separation device. 8. A raw material comprising a porous support, a liquid membrane in which a liquid is held in the support, a raw material gas chamber separated by the membrane, and a permeable gas chamber, the gas chamber containing the gas to be separated. Mixing characterized by introducing a gas and increasing the temperature of the membrane surface layer on the permeation gas chamber side of the liquid membrane relative to the temperature of the membrane surface layer on the raw material gas chamber side to separate specific components of the raw material gas. Gas separation methods. 9. The method for separating a mixed gas according to claim 8, characterized in that the heating of the membrane surface layer on the permeation gas chamber side of the liquid membrane is intermittent. 10. A porous support, a liquid membrane in which a liquid selected from an alkanolamine solution or an alkali metal carbonate solution is held in the support, and a raw material gas chamber and a permeation gas chamber separated by the membrane. , characterized in that a raw material gas containing carbon dioxide gas is introduced into the gas chamber, and the carbon dioxide gas in the raw material gas is separated by intermittently irradiating sunlight on the membrane surface layer on the permeation gas chamber side of the liquid membrane. A method for separating gas mixtures.