JPS63143955A - Gas separation method - Google Patents

Abstract

PURPOSE:To increase separation rate of a gas separating membrane, by ionizing mixed gas and increasing the concentration of a substance to be separated on the surface of the gas separating membrane. CONSTITUTION:The gas separation method is carried out by a gas separating membrane 17 and a device with an ionization device with an electrode, close to the gas separating membrane 17, consisting of an electric discharge pole 21 and a grounding pole 19, to which voltage is applied. When negative voltage is applied to an electric source for discharging 23, corona discharge is generated between the electric discharge pole 21 and the grounding pole 19 to ionize the gas around the electric discharge pole 21. At that time, in case of a substance with much of electronic affinity and easily converting into negative ion, for instance, air constituted with a mixture of oxygen and nitrogen, oxygen is selectively ionized. The ionized oxygen monocules charged as negative are attracted to the grounding pole 19 by static to increase highly the oxygen concentration around the surface of the gas separating membrane 17 and also increase separation rate to a great extent.

Description

Detailed Description of the Invention Technical Field The present invention relates to a method of separating gases using a gas separation membrane, and in particular, to a method of separating gases by applying ionization to a mixed gas using an electrode consisting of a discharge electrode and a ground electrode. It concerns the method of separation.

Conventional technology The method of separating a specific gas in a mixed gas using a gas separation membrane has a simple structure, and its use is increasing dramatically as the performance of separation membranes improves (magazine). “Chemistry Equipment 4 September 1985 issue.

112-117).

This membrane separation method utilizes the difference in the membrane permeation rate of each gas component in a mixed gas, and uses a non-porous membrane in which the gas dissolves and diffuses, and a porous membrane in which the gas is passed through by Knudsen flow. Porous membranes are known.

FIG. 3 is an explanatory diagram of a conventional gas separation system. When air (mixed gas), which is a mixture of nitrogen molecules 41 and oxygen molecules 43, is brought into contact with the gas separation membrane 17, the oxygen molecules 43, which are the substance to be separated, selectively pass through the gas separation membrane 17,
Oxygen-enriched air (oxygen-enriched gas) with a high oxygen concentration can be obtained.

The permeation rate of a gas separation membrane, that is, the rate of separation of substances to be separated, is determined by the difficulty of movement of substances in the membrane (diffusivity) and the extent to which substances to be separated (oxygen molecules) exist on the surface of the membrane (
The former depends on the physical properties of the gas separation membrane. In order to improve solubility, it is necessary to increase the supply of the substance to be separated to the membrane surface. Since the substances to be separated are uniformly present in the mixed gas to be processed, it is necessary to increase the supply rate of the gas to be processed in order to increase the supply of the substances to be classified to the membrane surface. becomes. However, if the gas velocity is increased too much, it will lead to destruction of the membrane, so there is a natural limit to this.

OBJECTS OF THE INVENTION The present invention aims to improve the separation rate by a gas separation membrane by subjecting a mixed gas to ionization treatment to increase the concentration of a substance to be separated on the membrane surface.

The gas separation method of the present invention is a separation process in which a mixture to be treated is brought into contact with a gas separation membrane, and the substance to be separated in the mixed gas is selectively passed through the gas separation membrane. In the method, an electrode consisting of a discharge electrode and a ground electrode to which a voltage is applied is provided near the gas separation membrane, and the mixed gas is subjected to ionization treatment to selectively charge the substance to be separated and supplied to the gas separation membrane, It is characterized by increasing the concentration of the substance to be separated near the gas by electrostatic attraction.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

The gas separation method of the present invention can be carried out using an apparatus equipped with a gas separation membrane and an ionization device in which an electrode including a discharge electrode and a ground electrode to which a voltage is applied is provided near the gas separation membrane. FIG. 1 is an explanatory diagram showing an example of the basic configuration of such a system. Air (mixed gas to be treated) is sent to a membrane module 15 via a filter 13 by a blower 11. The membrane module 15 is a gas separation membrane 17
A supply chamber 31 and a recovery chamber 33 are formed by partitioning. The pressure in the recovery chamber 33 is reduced by a pressure reduction pump 35, and a pressure difference is set between the supply chamber 31 and the recovery chamber 33. When air is sent to the supply chamber 31, oxygen selectively permeates through the gas separation membrane 17, enters the recovery chamber, and is recovered as oxygen-enriched air via the filter 37. In the present invention, in a gas separation system as shown in FIG.

Furthermore, ionization processing means consisting of an electrode provided near the gas separation membrane 17 and to which a voltage is applied is provided.

FIG. 2 is an explanatory diagram showing an example in which a discharge device is provided in close proximity to a gas separation membrane to perform electrostatic separation as an ionization treatment means. A discharge electrode 21 is provided in the supply chamber 31, and a screen-shaped ground electrode 19 is provided near the gas separation membrane 17. z3 indicates a discharge power source.

When a negative voltage is applied to the discharge power source 23, a corona discharge occurs between the discharge electrode 21 and the ground 19, and the gas near the discharge electrode 21 is ionized. At this time, ionization does not uniformly occur for various gases, but as is well known in the field of discharge technology, substances that have a large electron affinity and tend to become negative ions are selectively ionized. for example.

In the case of air, which is a mixed gas of oxygen and nitrogen, nitrogen is hardly ionized and oxygen is selectively ionized. The ionized and negatively charged oxygen molecules are attracted to the ground electrode 19 by Coulomb force (electrostatic force), and can dramatically increase the oxygen concentration near the surface of the gas separation membrane 17, thereby increasing the separation rate. Significant improvements are possible.

In addition, in the configuration shown in FIG. 2, by providing a screen-shaped ground electrode 19 in front of the gas separation membrane 17, it is possible to effectively prevent foreign substances entrained in the gas to be treated from being blown into the gas separation membrane. The life of the gas separation membrane can be improved.

In the above explanation, we have explained the separation (concentration) of oxygen from the air, but it is also possible to separate gases other than oxygen.
Differences in electron affinity between various gas components make it possible to concentrate specific gas components near the surface of the separation membrane. With the conventional technology, it is impossible to increase the concentration of the substance to be separated on the membrane surface to a level higher than the concentration of the mixture gas to be treated. Therefore, if an attempt is made to increase the supply of the substance to be separated to the membrane surface, it becomes inevitable to increase the supply rate of the mixed gas to be treated, which may lead to destruction of the membrane. On the other hand, according to the method of the present invention, the membrane surface concentration of one substance to be separated can be made equal to or higher than the component ratio, so that the gas separation rate is improved.

Further, in the above embodiments, it has been explained that the difference in electron affinity of each component is used to electrostatically separate and ionize the gas by corona discharge, but the method of ionizing the gas to be treated is not limited to this, for example, Ionization may be performed using an electron beam or the like.

In this case as well, an electrode is provided near the gas separation membrane, and a voltage is applied to the electrode to apply a bias to attract the charged substance to be treated.

The concentration at the surface of the gas separation membrane can be increased.

According to the present invention, a mixed gas to be treated is subjected to ionization treatment, and the substance to be treated is selectively ionized and charged by utilizing the difference in electron affinity of each component in the mixed gas. Seshime,
An electrode to which a voltage is applied is installed near the gas separation membrane, and the charged target substance to be separated is drawn toward the gas separation membrane by the electrostatic attraction between the electrode and the concentration of the target substance to be separated on the surface of the gas separation membrane. By increasing the separation rate of the gas separation membrane, the separation speed of the gas separation membrane can be improved.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are explanatory diagrams showing the gas separation method of the present invention. FIG. 3 is an explanatory diagram showing the principle of a gas separation membrane. 11...Blower 15...Membrane module 1
7... Gas separation membrane 19... Ground electrode 21...
Discharge electrode 35...Reducing pump patent applicant Sumitomo Heavy Industries Co., Ltd. Representative Patent Attorney 9 Masanobu Fuji -- and 1 other person 1・J,゛・l,...,j I' Figure 1 Cause 2 0 fox air

Claims (1)

[Claims] 1. In a gas separation method in which a gas mixture is brought into contact with a gas separation membrane and the target substance in the gas mixture is selectively separated by passing through the gas separation membrane, a discharge electrode and a ground electrode are connected near the gas separation membrane. An electrode to which a voltage of A gas separation method characterized by: