JPS62110727A - Separating method for gas - Google Patents

Abstract

PURPOSE:To increase gas separation efficiency and to improve economicity by rising gaseous raw material in temp. at liquid crystal critical point or above of liquid crystal contained in a liquid crystal-contg. type gas separation membrane and bringing it into contact with the liquid crystal-contg. type gas separation membrane. CONSTITUTION:Air raw material introduced into the inside of a heating chamber 12 by means of a blower 11 is directly heated with a petroleum burner 13 and risen in temp. at liquid crystal critical point or above of liquid crystal contained in a gas separation membrane and thereafter introduced into a gas feed chamber 14 arranged with a module M. Herein oxygen-enriched air is taken out from air and fed to a combustion furnace 16 via a blower 15 and made to an oxygen source of a combustion burner 13 or the like. In such a way, high combustion efficiency can be obtained in the combustion furnace 16. On this occasion, an aimed gas such as oxygen-enriched air can economically be obtained by increasing remarkably gas separation efficiency.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention covers a wide range of applications. Regarding the gas separation method using 1llllI,
Specifically, the present invention relates to a gas separation method that has high separation efficiency and can perform gas separation economically.

[Prior Art] There are various gas separation methods for extracting a specific component gas from a mixed gas. For example, in various combustion devices, it is necessary to supply combustion air, but in addition to 02,
Since it contains a large amount of non-flammable gas such as N2 and CO2, the combustion efficiency of the device is low, and the non-flammable gas is also heated during combustion and is emitted along with the exhaust gas, so there is a disadvantage that there is a large loss of heat. . Furthermore, since the amount of air supplied increases by the amount of nonflammable gas, the load on the feed blower also increases. Therefore, in order to improve the economic efficiency of combustion, it has been considered to eliminate the above drawbacks by using oxygen-enriched air instead of air, and various gas separation technologies have been proposed to obtain oxygen-enriched air from air. . Common gas separation technologies include cryogenic separation and pressure swing methods that utilize the selective adsorption properties of zeolite, but these methods require high operating costs and equipment depreciation costs, making it difficult to achieve economical combustion. Can not do it. Therefore, an economical gas separation technology is needed, and the gas separation membrane method has the potential to meet this demand. In other words, the gas separation membrane method is a method of obtaining a target gas by bringing a mixed gas into contact with a separation membrane and utilizing the difference in membrane permeability of each mixed gas component to increase or decrease the concentration of a specific gas after permeation. Compared to the above two methods, this method is simple in principle and does not involve a phase change, so it is said that it is possible to achieve economical waste separation. However, conventionally existing gas separation membranes have a permeability coefficient that indicates whether 1, ν constant gas permeates well or not, or a gas temperature ratio after permeation of two or more components in the mixed waste, or a gas temperature ratio before permeation. Subtraction 1 showing the value divided by 51 degrees
1 coefficient and the durability of the membrane are still insufficient, and the economy (1
+J It can't be said that it was borrowed that much, and there is still room for improvement °
[There is.

[Problems to be Solved by the Invention] The present invention has been made in view of the above circumstances, and improves the efficiency of waste separation in the gas separation membrane method, and improves the efficiency of the gas separation membrane method. There are also attempts to further improve economic efficiency, which is one of its strengths.

[Means for Solving the Problems] However, the uninvented method that achieves the above purpose is that when gas separation is performed using a liquid crystal-containing gas separation membrane, the source gas is separated from the liquid crystal contained in the separation membrane. The gist lies in that A is heated above the liquid crystal limit point and brought into contact with a liquid crystal-containing gas component 11[1]u.

[Function] In the present invention, a liquid crystal-containing gas separation membrane having a relatively high gas separation ability is employed as the gas separation membrane. There are various types of separation membranes. Typical examples include a polymer-liquid crystal membrane prepared by a solvent evaporation method from a mixed solution of a polymer and a liquid crystal material, and a polymer-liquid crystal film prepared by adding fluoride to a mixed solution of a polymer and a liquid crystal material. There is a polymer-liquid crystal film in which a small amount of carbon (fluorocarbon monomer) is dispersed.There is a fluorocarbon ternary composite film, but generally the polymer is vinyl chloride and the liquid crystal is polyvinyl chloride.
-Ethoxybenzylidene-4-butylaniline (hereinafter E
Examples include BBA) and 4-cyano-4-penderbiphenyl, but there are no particular restrictions on the materials.

However, the gas separation performance of the liquid crystal-containing gas separation membrane described in Section 2 cannot be said to be particularly outstanding, and this alone does not mean that it has the gas separation performance that was the goal of the wood invention. Improvements to agent 1 performance are required.

The present invention has been made in response to these demands by discovering that the gas separation performance of a liquid crystal-containing gas separation membrane is temperature-dependent, and utilizing this property to further improve the gas separation performance. It is.

That is, as an example of a liquid crystal-containing gas separation membrane, a gas separation membrane in which EBBA is included in the gaps of a network structure of vinyl chloride [
Vinyl chloride: EBBA=40:60 (weight ratio)], N2. He, CH4゜C3HB, isobutane, n-
When butane and other gases were brought into contact with each other and their permeability coefficient curves were examined, the results shown in FIG. 1 were obtained. Note that Tm is the melting point, Tc
means the liquid crystal limit point, the liquid crystal becomes a crystal below Tm,
It becomes a liquid crystal (flowable crystal) in a temperature range of Tm or more and Tc or less, and becomes a pure liquid in a temperature range of Tc or more.

As shown in Figure 1, there is a marked difference between the permeability coefficient curve in the temperature range below Tm and the permeability coefficient curve in the temperature range above Tc, and an outstanding permeability coefficient is obtained in the temperature range above Tc. I'll figure it out. That is, if the operating temperature range of the liquid crystal-containing gas separation membrane is set to be above the Tc point of the liquid crystal, a high transmission coefficient can be obtained.

By the way, various methods can be considered to increase the temperature range of the gas separation membrane itself to the Tc point or higher.Whatever method is used, the gas separation membrane is brought into contact with the raw material gas to be separated, so the raw material gas If the temperature is low, the gas separation membrane temperature will become equal to the raw material gas temperature after long-term use. For these reasons, in the present invention, the temperature of the raw material gas is raised above the Tc point and brought into contact with the gas separation membrane. As a result, the gas separation membrane temperature is also raised above the Tc point and maintained at this temperature, so that an excellent permeability coefficient can be obtained. There are no particular restrictions on the means for raising the temperature of the raw material gas, such as an oil burner or a gas burner.

Means such as an electric heater, heating with high-temperature steam, and temperature raising by adiabatic compression can be used.

[Example] Fig. 2 is a perspective view showing a module containing a rolled-up separation membrane unit, and Fig. 3 is a partially cutaway explanatory view showing the structure of the membrane unit in the rolled-up type portion 11. Separation membrane unit, 2 is a steel pipe housing, 3 is an air supply port, 4 is a residual gas discharge port, 5 is an oxygen-enriched air outlet pipe, 6 is a blind plate, 7 is a polymer membrane, 8 is a liquid crystal-containing gas Separation membrane (hereinafter referred to as rat) and 9 indicate a crude membrane, respectively.

The separation membrane unit 1 is a strip-shaped thin film laminate formed by laminating a gas component 1tllfllua,a on both sides of a coarse membrane 9 for permeated gas passages, and further laminating polymer membranes 7 and 7 for supply gas passages on both sides thereof. , 1f! Gas passage hole 10 in a part of the part
One end of the oxygen-enriched air take-off pipe 5 is sealed with a blind plate 6, and the other end is connected to a combustion device (not shown). ing. Further, both axial end faces and the outer center end face of the rough membrane 9 and the gas separation membrane 8 are sealed with a suitable sealing material, and the inner center end face and the outer center end face of the polymer membrane 7 are also sealed with a sealing material. The module M houses such a separation membrane unit 1 in a steel pipe housing 2 whose one end is closed, and the open side of the steel pipe housing 2 is sealed by a flange F. Further, an air supply port 3 is opened in the flange side space of the steel pipe housing 2, and a residual gas discharge port 4 is opened in the inner space.

When raw air is blown into the gas separation membrane module M having the above configuration from the air supply port 3, the air enters the unit from the side of the polymer membrane 7 of the gas separation membrane unit 1, and then the permeability of the gas separation membrane in the air increases. High oxygen selectively permeates the gas separation membrane 8 and reaches the crude membrane 9, flows inward through the crude 11U9, flows into the extraction pipe 5 through the hole 10 of the extraction pipe 5, and is collected and sent to the combustion device. supplied to On the other hand, gas separation membrane 8
The residual gas that does not pass through the polymer membrane 7 reaches the inner space of the steel housing 2 and is discharged from the residual gas outlet 4 to the outside of the system.

FIG. 4 is a schematic diagram showing a specific example device (combustion system) for carrying out the method of the present invention incorporating such a gas separation membrane module. The supply gas chamber 14 in which the module M is placed is heated directly by the burner 13 to raise the temperature to the liquid crystal limit point 10 of the liquid crystal contained in the gas separation membrane or higher.
to be introduced. Here, oxygen-enriched air is taken out from the air, and the oxygen-enriched air is supplied to a combustion furnace 16 via a blower 15 and serves as an oxygen source for a combustion burner or the like. Thus combustion furnace 1
6, high combustion efficiency can be obtained. 17 is the fuel tank, and 16 is the chimney.

Reference numeral 19 indicates a dilution air inlet.

In the method of the above embodiment, since the raw material air above the Tc point is fed to the module, the high separation function of the liquid crystal-containing gas separation membrane is exhibited, and oxygen-enriched air can be efficiently obtained.

In the above, an entrained gas membrane unit was used, but a unit of any shape such as a flat plate unit or a hollow fiber unit may be used.

Further, there is no particular restriction on the means for raising the temperature of the raw material air, and in addition to heating using a gas burner, electric heater, high-temperature steam, or combustion furnace exhaust heat, the temperature may be raised by adiabatic compression. Furthermore, the target gas obtained by the gas separation method of the present invention is not limited to oxygen-enriched air; on the contrary, nitrogen-enriched air may be used, or various gases such as those mentioned in the explanation of FIG. It may be used.

[Effects of the Invention] The present invention is configured as described above, and by dramatically increasing gas separation efficiency, it has succeeded in economically obtaining a target gas such as oxygen-enriched air.

[Brief explanation of drawings]

Fig. 1 is a graph showing permeability coefficient curves with the horizontal axis representing the temperature of various gases, Fig. 2 is a partially cutaway perspective view showing a gas component 1i11 membrane module, and Fig. 3 shows the structure of the gas separation membrane unit. FIG. 4, a partially cutaway perspective view, is a schematic diagram showing an apparatus according to an embodiment of the present invention. 1st eup

Claims (1)

[Claims] When performing gas separation using a liquid crystal-containing gas separation membrane, the raw material gas is heated to a temperature higher than the liquid crystal limit point of the liquid crystal contained in the separation membrane and brought into contact with the liquid crystal-containing gas separation membrane. gas separation method.