JPS607921A - Apparatus for gas separation membrane - Google Patents

Abstract

PURPOSE:To obtain high separation efficiency with a single gas separation operation by providing two membranes for separating a mixed gas by the difference in permeation velocity, and also providing a discharging means for discharging a part of a permeated gas from between said membranes. CONSTITUTION:A mixed gas charging means 1 for charging the mixed gas, two membranes 1A and 1B which are installed so that one surface of each membrane may be kept in contact with the passage of the mixed gas capable of separating the mixed gas by the difference in permeation velocity, a permeated gas discharging means 5 capable of discharging a part of the permeated gas from between the two membranes 1A and 1B, a separated gas discharging means 3 for taking out the separated gas after permeating the two membranes 1A and 1B, and a discharging means 4 for discharging the mixed gas which do not permeate the membranes 1A and 1B are provided to constitute the apparatus.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gas membrane separation device for separating and concentrating a mixed gas.

Conventional methods for separating mixed gases using membranes have been used for a long time, such as in the separation of uranium isotopes from nuclear fuel, but in recent years new membrane materials have been developed, and the fields of their use are expanding.

Specific examples of its use include oxygen enrichment devices and the recovery of hydrogen from exhaust gas in industrial processes, as well as attempts to use it to adjust the concentration of reactants in chemical reaction processes.

The principle of separation of mixed gases using this membrane is to utilize the difference in raw coal permeated in the membrane for each component, and the component with a high permeation rate is concentrated.

Therefore, in a conventional single-membrane gas separation device as shown in FIG. Further, a gas exhaust means 4 is provided for exhausting the mixed gas that has not passed through the membrane, and the principle thereof will be explained below.

First, consider a mixed gas of two components whose permeation rates in the membrane 1 struggle.

The composition before permeation is xX, and the composition after permeation is 2, which shows a high permeation rate.

The pre-permeation and post-permeation compositions of those exhibiting a small permeation rate are lx and 1-.2, respectively.

Next, when the pressure tpl of the mixed gas inflow section 7 and the pressure of the final permeation section 8 are Pl, Pl>Pl.

For those showing a large permeation rate and those showing a small permeation rate, the respective permeation rates are calculated as QA + QB (mol/y
+/, sec, atm'), and the area of membrane 1 is S, and the membrane permeation flow rate FA in FIG.
FβCmol/sec:] is as follows.

FA=S, QA(Plx-P2Z)...
...(1)Fn=S,QB(Pt (1x) Pl
(1-Z))・・・・・・(2) The composition ratio after passing through is
Since it is shown in equations (1) and (2) and is equal to the ratio of the respective permeation flow rates, "QAPlx -P2Z □-□, □... 1-X) Pl (IZ).

Now, in general, in gas separation, the separation coefficient α, which indicates the degree of separation, is expressed by the following equation as a ratio of the composition ratio before and after separation.

Using equation (3), equation (4) becomes as follows.

Now, in a separation operation using a membrane, the separation coefficient when the low pressure side pressure P2 is set to zero, that is, when the bank pressure effect that reduces the degree of separation is set to zero, is called the ideal separation coefficient α'' and shows the maximum value. .

In equation (5), by setting Pl-0, the ideal separation coefficient α'' can be expressed as follows using QA and Qs.

QA αfuki = □ ... Song (6) QB In general, operating conditions in membrane separation, that is, initial composition of component A, X1 operating pressure PlfP2, and component A.

When the permeation rates QA and QB of B are given, the composition 2 of component A after separation is given by the relationship of equation (3).

Further, the maximum value of the separation coefficient is QA/Qrr, as shown in equation (6).

The above membrane separation technology is very simple in principle and is an excellent technology that can be used to separate any mixed gases as long as the gas permeation rates are different.However, conventional gas separation equipment requires only one separation operation. There is a limit to the degree of separation, and therefore, in order to separate the target component to a predetermined concentration, a multi-stage device is required, and pressurization is required for each stage, making the device large-scale. In order to alleviate this drawback, there is a demand for an apparatus that can achieve a high degree of separation in -separation operations.

SUMMARY OF THE INVENTION The present invention has been made in order to eliminate the drawbacks of conventional gas membrane separators, and its object is to provide a gas membrane separator that can obtain a high degree of separation in -times of separation operations. .

That is, the gas membrane separation device of the present invention is arranged such that the mixed gas inlet means for introducing the mixed gas and one surface of the flow path for the mixed gas are in contact with each other, and the gas membrane separation device is arranged so that the mixed gas inlet means for introducing the mixed gas into the mixed gas is in contact with one surface of the flow path for the mixed gas, and the gas membrane separation device is arranged such that the mixed gas inlet means for introducing the mixed gas into the mixed gas is in contact with one surface of the flow path of the mixed gas, and the gas membrane separation device is arranged such that the mixed gas inlet means for introducing the mixed gas into the mixed gas is in contact with one surface of the flow path of the mixed gas, and the two membranes that can separate the mixed gas, a permeated gas exhaust means that can exhaust a part of the permeated gas from between these two membranes, and a separated gas extraction means that takes out the separated gas that has permeated these two membranes. and a gas exhaust means for exhausting the mixed gas that has not passed through these membranes.

An embodiment of the present invention will be described below with reference to FIG.
The gas membrane separator of the present invention in the principle diagram of FIG. 2, which is shown using the same symbols and numbers as the conventional example in FIG. two membranes iA, jB that are arranged so that their surfaces are in contact with each other and that can separate the mixed gas by the difference in the permeation rate of these individual gases; and these two membranes 1A and 1B.
A permeated gas exhaust means 5 that can exhaust a part of the permeated gas from between the two membranes 1A and 1B, a separated gas extraction means 6 that extracts the separated gas that has permeated through these two membranes 1A and 1B, and It is constructed by providing a gas discharge means 4 for discharging the mixed gas that has not been mixed.

Therefore, the principle of the gas membrane separator of the present invention having the above-mentioned configuration is that by continuously discharging a part of the medium concentration component from between the two membranes 1A and 1B by the permeate gas discharging means 5, the final A high-concentration gas is obtained as a permeate gas, and if the pressure of the intermediate discharge part 6 is Pl and the composition of component A there is y, then the composition of component B in the intermediate discharge part B is 1-y.

Mixed gas inflow section 7, intermediate discharge section 6, and intermediate discharge section 6
and the final transmission section 8, the following two equations similar to equation (3) are obtained.

Y QAPlx -P'y □=-0・River...(7) 1 y QBPH(1-x)-P'(1-y)Z QA
P'y-P2Z □=-・・・・・・・・・・(8) 1-Z Qn P'(1-y) P2 (1-Z) Operating conditions, namely Pt + P', P21 X, QA
, QB are given, the composition Z of the component A of the final permeated gas can be determined by solving equations (7) and (8) simultaneously.

Next, a specific example using this gas membrane separation device and a case using the conventional single membrane shown in Fig. 1 will be explained using equation (3) and (7),
The results calculated using equation (8) are shown in the table below.

(Margins below this page) In addition, here, membrane 1. IA and IB are made of porous glass, and the hydrogen permeation rate is set to 4.72 x 10' (mo115
ec, m'.

atm ), and - carbon oxide permeation rate of 1.38
X 10 (mol/see, rr?, atm
).

As seen in the above table, the separation of mixed gases by the gas membrane separation device of the present invention shows higher separation than the conventional method in all cases.

The gas membrane separation device of the present invention can be effectively applied to any membrane that separates mixed gases based on differences in permeation rate.

Therefore, the gas membrane separator of the present invention can obtain a highly concentrated gas in - times of separation operations, and can obtain a highly concentrated gas with a lower pressure operation than a conventional gas separation device using a single membrane. The same resolution as membrane devices can be obtained.

Furthermore, when using a membrane separation device in multiple stages, the gas membrane separation device of the present invention has the advantage of being able to reduce the number of stages in the device.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a conceptual diagram showing the principle of a conventional single membrane gas separation device, and FIG. 2 is a conceptual diagram showing the principle of a gas membrane separation device in an embodiment of the present invention. IA, IB... Membrane, 2... Mixed gas inflow means, 3.
... Separated gas extraction means, 4... Gas discharge means, 5...
・Permeate gas exhaust means.

Claims (1)

[Claims] A mixed gas inlet means for introducing the mixed gas, and a membrane arranged so that one surface is in contact with the flow path of the mixed gas and capable of separating the mixed gas based on the difference in permeation rate of each gas. , a permeated gas discharge means capable of discharging a part of the permeated gas from between these two membranes, and a separated gas extraction means that extracts the separated gas that has permeated through these two membranes;
A gas membrane separation device characterized by having a gas discharge means for discharging the mixed gas that has not passed through these membranes.