JPS6365930A - Light gas purifier - Google Patents

Abstract

PURPOSE:To obtain a high-purity light gas at high yield by introducing gas fed from a compressor of material gas into both a purifier equipped with a gas separation membrane and a pressure swing absorber and combining the permeated gas and purged exhaust gas to a front flow of the compressor of the material gas. CONSTITUTION:A material gas in compressed with a compressor 8 and one part is introduced into a purifier 3 equipped with a gas separation membrane, and light gases such as He permeating through a separation membrane 11 is led to an introduction pipe 2 of the raw material, and also nonpermeating impure components are discharged to the outside of the system through an exhaust pipe 7. On the other hand, the residual part of the material gas is introduced into pertreating adsorption towers 10a, 10b to absorb and remove water content and CO2 and thereafter led to a pressure swing absorber 5 to absorb impure components in adsorption towers 12a, 12b, and light gas is recovered in a product tank 13. Absorbed impure components are desorbed by using light gas purge gas is discharged from the adsorption towers 12a, 12b and thereafter returned to the feed pipe 2 of the raw material via a pipe 25 for circulating purge gas.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a purification and recovery device for light gases such as helium and hydrogen, and more specifically, an apparatus for purifying and recovering light gases such as helium and hydrogen. The present invention relates to a light gas purification device that is simple in itself and whose operation is easy to control.

[Conventional technology]

Practical methods for purifying and separating one type of light gas component from a mixed gas include the low temperature adsorption method, the coagulation method, the separation membrane method, and the pressure swing adsorption method. The swing adsorption method has the advantage of being more versatile than other methods because it can be operated at room temperature. However, since it is not possible to satisfy both high purity and high recovery rate by implementing the above-mentioned separation membrane method and pressure swing adsorption method alone, they are used as a supplementary role to the low-temperature adsorption method and coagulation method, or are used as a combination of both methods. Often used in combination. In particular, the combination of separation membrane method and pressure swing adsorption method has in common that both methods can be operated at room temperature, and they also complement each other's strengths and weaknesses.
This is considered the most ideal combination. FIGS. 2 and 3 are schematic explanatory diagrams of a heel cord manufacturing apparatus (Japanese Patent Application Laid-Open No. 1271509/1982) according to the above combination example previously proposed by the present inventors. FIG. 2 shows a system in which a gas separation membrane purification device 3 and a pressure swing adsorption device 5 are connected in series.
, 10b to remove N2 and CO2 components, and then introduced into the gaseous membrane purifier M3 via the inlet pipe 21. Among the raw material gases introduced under pressure into the purification device 3, light gas (He) that exhibits permeability to the molecular s membrane 11 is sent from the separation pipe 22 to the next stage compressor 8b, and is passed through the separation membrane 1.
Impurity components (02, N2, etc.) that are impermeable to 1 are discharged from the system through the discharge pipe 7.

The processed gas (hereinafter also simply referred to as semi-finished product gas) of the gas separation membrane purification device 3 pressurized by the compressor 8b is transferred to either the adsorption tower 12a or 1 of the pressure swing operator device 5.
2b, impure components in the semi-finished product gas are adsorbed by an adsorbent such as activated carbon, and the product gas that has passed through the adsorption tower 12a or 12b is recovered into the product tank 13 via the recovery pipe 23. Note that when the impurity component adsorption capacity of the adsorption tower 12a or 12b reaches saturation, the product gas from the product tank 13 is used as a purge gas and is transferred from the purge pipe 24 to the adsorption tower 1.
2a or 12b and purge gas containing impure components (
(hereinafter also simply referred to as circulation gas) is the purge gas circulation pipe 2.
5 and is returned to the raw material gas supply pipe 2 for reuse.

The device shown in FIG. 3 is the one in which the arrangement order of the gas separation membrane purification device 3 and the pressure swing adsorption device surface 5 shown in FIG. It is used for purposes. Therefore, although the product purity of the light gas is inferior, the load on the separation membrane 11 is slightly reduced. Helium and hydrogen purification devices using these devices have succeeded in obtaining the components to be recovered with high purity and high recovery rate.

[Problems to be solved by the invention] In the apparatus shown in FIG. is also at low pressure, and when these gases are then supplied to the pressure swing adsorption snowmaking 5 or gas separation membrane purification device 3 provided in series,
A separate compressor must be installed in front of each device to regulate or increase the pressure. Furthermore, since the above-mentioned circulating gas will be intermittently discharged from the pressure swing operator sound system 5, a buffer M for equalizing the gas pressure must be separately provided in the purge gas circulating pipe 25. There must be.

Therefore, in order to operate the above-mentioned equipment continuously, the gas pressure on the inlet and outlet sides of the compressor must be controlled using numerous control devices in accordance with the operating conditions of the entire equipment. It becomes necessary to set up a complicated control system, and
This requires complicated pressure control operations.

Therefore, the present inventors provide a purification device that is easy to operate and control, and is a B-type equipment, based on the idea of purifying light gas by using a gas separation membrane purification device and a pressure swing adsorption device in combination. As a result of various studies aimed at achieving this goal, the device of the present invention has been completed.

[Means for Solving the Reversal Points] The purification apparatus of the present invention, which has achieved the above object, branches the outlet side of the raw material gas compression 1 and the inlet side of the gas separation membrane purification apparatus and the inlet side of the pressure swing adsorption apparatus. The main feature is that the permeate gas outlet side of the gas separation membrane device and the purge gas outlet side of the pressure swing adsorption device are connected to the raw material gas introduction section on the compressor inlet side. .

[Function] In the present invention, the compressor provided before the gas separation membrane purification device and the pressure swing adsorption device is shared, that is, there is only one compressor, and the raw material gas pressurized by the compressor is shared between the two devices. The configuration is such that the feed is branched and fed to each of the above. Therefore, as long as the supply ratio of the raw material gas to both of the above devices is maintained appropriately, the raw material gas can be simultaneously supplied to the gas separation membrane purification device and the pressure swing adsorption device using equipment with a simple structure. Pressure control can also be easily performed.

The light gas that has passed through the separation membrane in the gas separation membrane purification device is circulated to the inlet side of the compressor via the separation pipe to increase the light gas concentration and gas concentration in the raw material gas. In this device, heavy gas components that do not pass through the separation membrane are discharged out of the system as usual.

Therefore, since the @ quality gas component in the raw material gas supplied to the pressure swing adsorption device is increased in advance, the light gas purified and recovered by the device can achieve a high concentration. The purge gas used for purging the adsorption tower is configured to be returned from the pressure swing adsorption device to the input side of the compressor via a circulation pipe to prevent wasteful discharge of the components to be recovered. With the above configuration, the light gas to be recovered can be obtained with high purity and high recovery rate.

[Example] FIG. 1 is a schematic explanatory diagram showing a typical example of the present invention, which will be described below based on an example in which He is recovered and purified from a mixed gas of He and air. A compressor 8 is installed in the raw material gas supply pipe 2.
is connected to compress the raw material gas. The compressed pressurized gas is distributed to branch pipes 27a and 27b via pressurizing pipe 26. One branch pipe 27a is connected to the inlet side of the gas separation membrane purification device 3, and the He component that permeates through the separation membrane 11 of the device 3 is guided to the raw material gas supply pipe 2 via the separation pipe 22.
Impurity components that do not pass through the separation membrane 11 are discharged from the system through the discharge pipe 7.

On the other hand, pretreatment adsorption towers 10a and 10b for removing H2O and CO are connected to the branch pipe 27b, and the adsorption towers 10a,
The H2O and CO2 components adsorbed in 10b are desorbed and released by the suction blower 9 at appropriate times. The raw material gas from which H2O and Co2 components have been removed by the pretreatment adsorption towers 10a and 10b is led from the introduction pipe 21 to the pressure swing adsorption device 5, and the pressurized raw material gas is introduced into either of the adsorption towers 12a and 12b. , impurity components in the raw material gas are adsorbed by an adsorbent, and He, which is a component to be recovered, is recovered from the recovery pipe 23 into the product tank 13. In addition, adsorption towers 12a and 12b
The impurity components adsorbed on the product tank 13 are desorbed using the recovered He, and the purge gas is supplied to the 8 compressors through the purge pipe 24, the adsorption tower 12a or 12b, and the purge gas circulation pipe 25. Returned to tube 2. Since the purge process of the adsorption tower described above is performed intermittently, the amount of gas flowing through the raw material gas supply pipe 2 will fluctuate, but the raw material gas and the gas separation membrane purification device 3 will be supplied in a constant amount. Since a large amount of semi-finished product gas circulated from the compressor m8 is constantly supplied to the raw material gas supply pipe 2, fluctuations in the gas amount due to the circulating gas (purged gas) on the compressor m8 side are small. It does not have a large effect on the compression performance.

The supply ratio of raw material gas from the pressurizing pipe 26 to the branch pipes 27a and 27b is 10 to 40% on the branch pipe 27a side;
It is preferable to set it to about 90 to 60% on the 7b side, and the means for adjusting the supply ratio employs automatic control mechanisms such as pressure adjustment, flow rate adjustment, and concentration adjustment. For example, minute I! A concentration adjustment mechanism is provided on the membrane purification device 3 side, a flow rate adjustment mechanism is provided on the pressure swing adsorption device 5 side, and a pressure adjustment mechanism is provided on the compressor side to adjust gas distribution to each branch pipe 27a, 27b.

Example 1 In the purification device M shown in FIG. 1, He: 80% by volume, air = 2
A raw material gas of 0% by volume (H2O and CO2 have been processed in the pretreatment adsorption tower) is supplied from the introduction pipe 21, and after being pressurized to 20 kg/cm2G by the compressor 8, it is sent to the gas separation membrane purification device 3 side. 20% and 80% were distributed to the pressure swing adsorption device 5 side. Gas content I! Polyester was used for the Ill membrane, activated carbon was used as the adsorbent for the adsorption towers 12a and 12b, and the switching period in the pressure swing adsorption apparatus was set to 5 minutes per cycle. As a result, the average He purity in the recovery tube 23 is! The He recovery rate reached 19.9995%, and the He recovery rate was 98%.

Example 2 An experiment was conducted under the same conditions as in Example 1, changing the composition of the raw material gas in the introduction pipe 21 to He: 93% by volume and air near volume%. The purity was 99.9997%, and the He recovery rate was 9.
9.3% was obtained. In the above example, the He1i product was explained, but the apparatus of the present invention can also be used in the purification of other light gases in the same manner as in the above example.

[Effects of the invention] By using the device of the present invention, light gas purification with high purity and high recovery rate can be performed only by operation at room temperature, and the device requires simple equipment and operation control can be easily performed. It became like that.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram showing a typical embodiment of the apparatus of the present invention, and FIGS. 2 and 3 are schematic explanatory diagrams showing an example of a conventional purification bag M. 1... Pretreatment section 2... Raw material gas supply pipe 3.
... Gas separation membrane purification device 4 ... Product gas extraction pipe 5 ... Pressure swing adsorption device 7 ... Discharge pipe 8, 8a, ~8d ... Compressor 9 ... Suction blower lOa, IQb. ...Pretreatment adsorption tower 11 ...min Bt n5 12 a
, 12 b = IIA landing tower l3... Product tank 14-20... Three-way valve 21... Inlet pipe
22...Separation pipe 23...Recovery pipe
24... Purge pipe 25... Purge gas circulation pipe

Claims (1)

[Claims] A light gas purification device consisting of a gas separation membrane purification device and a pressure swing adsorption device, in which the outlet side of the raw gas compressor is branched and connected to the inlet side of the gas separation membrane purification device and the pressure swing adsorption device, respectively. A light gas purification apparatus characterized in that the permeate gas outlet side of the gas separation membrane device and the purge gas outlet side of the pressure swing adsorption device are configured to merge into the raw material gas introduction section on the compressor inlet side.