JPS6133215A - Gas refining method - Google Patents

Abstract

PURPOSE:To take out a prescribed gaseous component with high purity in a gas refining method by capturing the pure gas components moving in prescribed holding time by making use of the difference in the developing speed by the selective adsorption of a multi-component gaseous mixture. CONSTITUTION:The gaseous raw material is supplied from a gaseous raw material supply device 1 to a developer type separating column 7 (8) at one time to develop the gaseous raw material in the separating column. The impurity component preceding to the intended component, the intended component and the impurity component succeeding to the intended component are successively discharged from said column. A selector valve 22 is changed over to an impurity component discharge path 25 to discharge the impurity components through a discharge path when a detector 24 detects the impurity components. The selector valve is changed over to a capturing device to capture the intended component when the intended component is detected. A raw material supply column 5 is provided to the raw material supply device. The operation is started only after the residual components of the previous operation are removed under the reduced pressure by a vacuum pump 4.

Description

Detailed Description of the Invention <Industrial Application Field> The present invention relates to a method for separating and purifying desired gas components from a multi-component mixed gas, for example, selectively separating and purifying acetylene, pervapebutane, carbon dioxide gas, silane gas, etc. To provide something that can be purified automatically to extremely high purity using adsorption.

<Prior art and its problems> Conventionally, methods for purifying raw material gas by purifying and separating desired gas components from a multi-component mixed gas and removing trace impurities include separation by condensation and liquefaction of vapor, basic or acidic absorption, etc. Removal of impurity components by agents (e.g. S removal from waste gas)
There were several methods, such as ○ process, removal of NOx), and separation methods using semipermeable membranes.

For example, acetylene is used for cutting metals due to its high calorific value and excellent combustibility, and it also has active properties such as having a triple bond in its molecule and being easily attacked by electrophilic agents.
It has occupied an important position as a starting material for acetylene chemistry.

However, in the current state of industrial supply of acetylene, acetylene gas is usually sold after being dissolved in legal solvents such as acetone, so the acetylene gas taken out of the container inevitably contains several percent of solvent vapor. Therefore, it is not suitable for producing high-quality carbon black or for research materials for physics and chemistry, and high-purity acetylene gas is required in various industrial fields.

Furthermore, since the carbon dioxide gas used in carbonated drinks is used for food, it is better to have as few impurities as possible, but industrially supplied carbon dioxide gas contains sulfur compounds such as sulfur dioxide, mercaptans, and hydrogen sulfide. It is contained in a small amount, has an odor, and may have an adverse effect on the human body, so carbon dioxide with a high M content is desired.

Furthermore, silane gas, which is the main raw material for silicon-based semiconductors, needs to be highly pure in order to improve the quality of semiconductors, but currently Moasilane 5iHa contains a small amount of disilane 5i2He, which lowers the purity and lowers the purity. ,
Since this disilane has the property of spontaneously igniting and is dangerous when it comes into contact with the atmosphere, there is a demand for the removal of disilane as an impurity.

As described above, although there are many fields in the industry that require the purification of raw material gas, there have been few methods to easily and accurately increase the purity of raw material gas that can be applied to all gases. .

Means for Solving Problems〉 The present invention separates a multi-component mixed gas into gases by utilizing the difference in deployment speed due to selective adsorption, and selectively purifies a predetermined component gas therein. This is a separation method that utilizes the principle of so-called gas chromatography to capture pure component gases that move over a predetermined retention time and extract target components with high purity.

Originally, gas chromatography was applied to analysis technology, but in recent years, the diameter of the separation tube has become smaller (1 mm or less) and the length Currently, they are designed to be longer (about several tens of meters).

The present invention differs from this current state of affairs by using gas chromatography not as an analysis technique but as a purification technique, and has a configuration that enables analysis by capturing target components and automatically removing other impurity components. To provide a method in which a target component can be purified and separated to a high degree of purity by adding a selective capture configuration that is light in exclusion.

That is, a separation column 7 (8) filled with a developing agent, an impurity component discharge passage 25, and a separation column 1! ! 28 (30) Nyo)
A switching valve 22 is arranged downstream of the separation column 7 (8) in conjunction with the component detector 2-t.
The downstream side is branched, and one side is connected to the trap 28 (30), and the other side is connected to the impurity component discharge path 25, respectively.

Then, the raw material gas is supplied all at once from the raw material gas supply device 1 to the developer-type separation column 7 (8), and the developer-type separation column 7 (8)
The raw material gas is expanded in the chamber, and the preceding impurity component preceding the target component, the target component, and the subsequent impurity component connected to the target component are sequentially flowed out, and when the detector 24 detects the preceding impurity component and the subsequent impurity component, switching is performed. The valve 22 is switched to the impurity component discharge path 25 to discharge the impurity component from the discharge path 25, and if the target component is detected by the detector 24, the switching valve 22 is switched to the trap 2.
8 (30), and capture the target component in the trap 28 (30).
) and extract the target component from the target component capture device 28 (30) (the reference numerals are shown in FIGS. 1 to 8 as reference examples).

The above-mentioned separation column is preferably a cylindrical tube with a large diameter and short length. For example, one with a diameter of 10-20 mm and a length of about 0.5 m is used to purchase raw materials approximately 100 times the amount of samples normally used for analysis. We are able to supply the quantity.

In addition, as the developing agent packed in the separation tower, silica gel,
Adsorptive solid powders such as activated carbon, activated alumina, and synthetic zeolite are impregnated with low-volatility liquids such as DMF and PEG. Due to the difference in the molecular weight of the components and the difference in the magnitude of the intermolecular force between the component and the molecules constituting the developing agent, the component is separated into each component through repeated adsorption, desorption, absorption, and evaporation in the separation column. .

On the other hand, a raw material gas component detector detects, as a signal, the difference in thermal conductivity between the carrier gas from the separation column and the eluate gas, which is a mixture of the carrier gas and the raw material gas, and this detection time is determined in advance. By comparing the set time for the target component to appear (i.e., retention time) and the time for separation to end, the switching valve can be operated to transfer the target component to the trap, or to control impurities before or after the target component. The components are automatically switched to be conveyed to the impure component discharge path.

<Example> A gas purification apparatus for carrying out the method of the present invention will be described below.

1 to 8 are schematic system diagrams of the present purification apparatus. The purification apparatus consists of a raw material supply apparatus 1 and a separation apparatus 6. The raw material supply apparatus 1 is connected to a transport path 2 for raw material gas and carrier gas.
3 and a vacuum pump 4 are connected to a raw material supply tower 5, and the separation device 6 includes two separation towers 7.8, a target component capture device 28.30, an impure component discharge path 25, and a collection cylinder 35. (See Figure 4).

The raw material gas transport path 2 and the carrier gas transport path 3 are connected via a four-way valve 13, and a pressure reducing valve 14 is interposed in the middle of the raw material gas transport path 2, and a needle valve 15 is interposed in the middle of the carrier gas transport path 3. At the same time, the downstream side of the four-way valve 13 is branched, and one side is connected to the raw material supply tower 5 and the other side is connected to the four-way valve 16.

Further, the vacuum pump 4 is connected to the raw material gas transport path 2 via the three-way valve 17, and the transport path 2 connects the three-way valve 17 and the four-way valve 13.
A three-way valve 18 is interposed at the top, and its branch passage 19 is connected to the lower end of the raw material supply tower 5.

On the other hand, the downstream side of the four-way valve 16 connecting the raw material supply device 1 and the separation device 6 is branched into three directions, and two of the two directions are connected to a separation column 7.
．． 8 are connected in parallel, and the remaining one direction is connected to the atmosphere discharge path 20.

Both lower ends of the separation tower 7.8 are connected via a four-way valve 21, and a four-way switching valve 22 for capture and discharge operations is located downstream of the four-way valve 21.
The four-way valve 21 is connected to the four-way valve 21 by a bifurcated transport path, and a component detector 24 is interposed in one of the branch paths 23 to convert the switching four-way valve 2 to the four-way valve 21.
2, and the other side is connected to impurity component discharge path 25.
shall be.

The four-way switching valve 22 receives the signal from the component detector 24 and connects the impurity component discharge path 25 and the target component capture device 2B, which will be described later.
(30).

Then, the downstream side of the switching four-way valve 22 is branched, and the four-way valve 26 is connected to one side, and the three-way valve 27 is connected to the other side, and two of the three-way branch paths of the four-way valve 26 are connected to two. The inlets of the target component traps 28 and 30 are each connected in parallel,
The raw material extraction path 31 is connected to the remaining one.

In addition, each upper outlet of the trap 28, 30 is connected to the three-way valve 27.
Re-main line 32.33 that connects to the carrier gas and conveys the carrier gas.
shall be.

Both of the traps 28 and 30 are configured to circulate liquefied nitrogen to cool the inside of the container to, for example, around -196° C., so that the target component in the raw material gas and the carrier gas can be separated into a gas-liquid or a gas-solid. .

As shown in the PTFJ8 diagram, the raw material take-out passage 31 is connected to the collecting cylinder 35 through an inlet/off valve 34 on the downstream side thereof.
Further, the collection cylinder 35 is connected to a vacuum pump 37 via an on/off valve 36, thereby making it possible to reduce the pressure in the raw material extraction passage 31.

In addition, a carrier gas discharge passage 38 is branched from the raw material take-out passage 31 upstream of the inlet/off valve 34, and this discharge passage 38 is assembled into the raw material supply device 1 via the inlet/cut valve 39. Connect to the vacuum pump 4 installed.

The process of purifying and separating target components using a gas purification apparatus having such a gas purification system will be sequentially explained using purification of acetylene gas as an example.

That is, as mentioned above, commercially available dissolved acetylene
Or, in addition to legal solvents such as acetone, methane, hydrogen, -
Since it contains several percent of impurity components such as carbon oxide, carbon dioxide, oxygen, and nitrogen, it is intended to be purified using this purification apparatus.

The carrier for developing the raw material gas into each component in the separation column is preferably an inert gas such as hydrogen, helium, nitrogen, or argon. was used.

(1) Vacuuming step As shown in FIG. 1, the three-way valves 17 and 18 are switched, the raw material supply tower 5 is connected to the vacuum pump 4, and the residual components from the previous operation in the raw material supply tower 5 are removed. Eliminate vacuum.

In addition, if the gas flow in this process is indicated by the symbols in the figure, it is 5 → 19.
→18→17→4.

(2) Process for supplying raw material acetylene gas As shown in FIG. A fixed amount of acetylene gas is supplied to the raw material supply tower 5 at a low pressure.

In addition, the flow of the raw material gas in this process is 14 → 17 → 18 → 1
9→5.

(3) Process of supplying raw material acetylene gas to the separation column by conveying carrier gas As shown in FIG. A gas supply source is communicated with the raw material supply tower 5, and the gas is continuously supplied to the raw material supply tower 5 while maintaining a predetermined flow rate through the needle valve 15.

At this time, when the four-way valve 16 is switched to the separation column 7, the four-way valve 1
By the above-mentioned switching operation in step 3, the raw material supply tower 5 is communicated with the separation tower 7, so that the raw material acetylene in the supply tower is introduced into the separation tower 7 while being carried by the carrier gas.

The flow of carrier gas in this process is 15 → 3 → 13
→18→19→5→13→16→7, and the flow of raw material acetylene gas becomes 5→13→16→7.

(4) Pre-cut process As shown in FIG. 4, when the raw material acetylene gas is introduced into one of the separation towers 7, the four-way valve 21 is switched to the branch path 23, and the acetylene component of the raw material gas is expanded before the acetylene component. Preliminary impurity components such as oxygen, nitrogen, carbon dioxide, and methane are bricuted.

That is, since the separated gas led out from the outlet of the separation column 7 is tracked by the component detector 24, while the impure components preceding the target acetylene component are flowing through the branch path 23, the gas from the detector 24 is In response to the signal, the four-way switching valve 22 is automatically switched to the impurity component discharge path 25 side.

In this case, by the above-mentioned switching operation of the four-way valve 21, the impurity component discharge path 25 is communicated with the other separation column 8, and the separation column 8 is connected to the other separation column 8.
is communicated with the atmospheric discharge passage 20 by the switching operation of the four-way valve 16 in the main process, so the preceding impurity components are removed from the separation column 8.
will be released into the atmosphere through

(The flow of impure component gas in this process is 7 → 21 → 24 → 2
2→25→21→8→16→2o.

In addition, in this step, as the expansion of the separation column is progressing, the carrier gas is continuously conveyed within the separation column 7 (the same applies in the following steps), and therefore the carrier gas is the same as the impure component gas. released through a channel.

(5) Capture process As shown in FIG. 5, when the separation tower 7 progresses and acetylene gas, which is the target component, flows out from the outlet into the branch passage 23, the signal from the detector 24 is sent to the four-way switching valve 22. Then, the four-way valve 22 is switched to the trap maze.

At this time, the four-way valve 26 is switched to one of the traps 28, and the three-way valve 27 is switched to the on/off four-way valve 2-2, so that the high-purity acetylene component is transferred to the trap 28.
8 and is cooled by liquid nitrogen at an extremely low temperature (around -i96°C) to solidify (by the way, the melting point of acetylene at normal pressure is -82°C).

On the other hand, since the carrier gas (hydrogen gas) conveyed to the trap 28 has a boiling point of 1253'C (normal pressure), it maintains a soot-like state and is easily separated into gas and plane from acetylene. .

Then, from this carrier or trap 28, it passes through the impure component discharge passage 25, enters the separation tower 8 which is not being expanded, and is discharged into the atmosphere from the atmosphere discharge passage 2°.

At this time, since pure carrier gas is conveyed from below to above to the separation column 8, the impurity components remaining in the developing agent in the separation column can be removed in the pre-purification step to regenerate the separation column. can.

The flow of high-purity acetylene gas in this process is from 7 to 21.
→24→22→26→28, and the flow of carrier gas is 7→21→24→22→26→28→27→22
→25→21→8→16→20.

(6) Backfluge unit process As shown in FIG. 6, when the separated components from the separation column 7 become impure components that follow the acetylene gas, a signal from the detector 24 is sent to the four-way switching valve 22, and the corresponding The four-way valve 22 is switched to the impurity component discharge path 25, and the same operation as in the pre-cut process described above is performed to discharge subsequent impurity components, such as water and 7 setone, into the atmosphere.

The flow of impurity components in this process is 7 → 21 → 24 →
22→25→21→8→16→20.

(7) Carrier gas removal process from the trap As shown in FIG.
Open the cutout 39 to communicate with the hnn container 28 and the vacuum pump 4. At this time, the connection between the trap 28 and the separation column 7 is cut off by the switching operation of the four-way valve 26.

In this way, the carrier gas stored in the trap 28 is removed from the exhaust passage 38, so there is no possibility that the carrier gas will be mixed in as impurities when taking out the high-purity acetylene gas.

(8) Removal process of high purity acetylene As shown in Fig.
5 to bring the inside of the cylinder into a reduced pressure state, then close the in/out turn 36 and open the in/out turn 34.

Then, by returning the trap 28 to room temperature, the solidified acetylene component is turned into a gas and taken out into the collection cylinder 35.

The flow of high-purity acetylene is 28 → 26 → 31
→It becomes 35.

In this acetylene refining process, when one of the separations is completed after the backflipping process, the regeneration of the other separation tower ends at the same time, so that the raw material previously supplied to the raw material supply tower is The gas (that is, the next refining cycle has already progressed to the raw material supply step (2)) is started to be supplied to the separation column where regeneration has been completed, and the process proceeds to the capture step.

That is, before one purification process is completed, the next purification process is performed in parallel to utilize vacant separation columns and traps, thereby increasing purification efficiency.

The cycle operation described above is actually fully automated using a program controller based on the indications from the component detector and a pneumatically operated valve. Safety operations are incorporated to facilitate safety and management of refining operations.

FIG. 9 is a separation chromatogram obtained by batchwise continuation of the raw material acetylene gas using the above-mentioned purification device. Of the symbols indicating the retention time range, part A corresponds to the impurity component preceding the target component, and the pre-cutting step Part B corresponds to the target acetylene component and is the range in which the capture process should be performed. Part C corresponds to the impurity components following the target acetylene component, and the back 7 latching steps are performed. This is the scope of implementation.

Experimental examples in which this purification method is applied to various raw material gases will be described below.

(Experiment Example 1) Book N51! When the composition of the high-purity acetylene gas extracted by applying the method to commercially available dissolved acetylene gas was analyzed, the following results were obtained.

For comparison, the composition of commercially available acetylene gas without being purified is also shown.

According to the above results, the acetylene subjected to this purification method is 99.9999% (so-called six nine)
By achieving the above-mentioned high purity, it is not only suitable as a research material for pure physics and chemistry, but also can be indispensable for the production of high-quality black carbon.

Also, according to the table above, the main residual impurity is oxygen (0
, 2 ppm) and nitrogen (0.5 ppm), and it is clear that these are air components remaining in the system of the equipment that implements this purification method.
It is expected that acetylene gas of even higher purity can be obtained.

(Experimental Example 2) The compositions of normal butane and isobutane purified and separated by applying this purification method to commercially available industrial butane were analyzed, and the following results were obtained.

In the above purification operation, the developing material packed into the separation column was DMF 26% supported on activated alumina, and the separated normal butane and isobutane were liquefied and captured in a trap cooled with liquefied nitrogen. .

For comparison, the composition of industrial butane without being purified is also shown.

(Left below) One of the new uses of butane that is attracting attention is the propellant used in near-sol cans. has been attempted to be used as an encapsulated drug in place of a mixture of normal butane, isobutane and propane having a predetermined vapor pressure.

However, as shown in the table above, industrial butane is a mixture of normal butane and isobutane, and since it is not possible to obtain an appropriate injection pressure with the current mixing ratio, each butane isomer is separated from the mixture and the prescribed ratio is adjusted. It is desired to adjust the vapor pressure by mixing with

Therefore, if industrial butane is purified using this purification method, normal butane can be extracted with a purity of 99.99% and isobutane with a purity of 99.96%, as shown in the table above, and the appropriate injection pressure can be obtained. It can be obtained simply and quickly by mixing unit components.

° Moreover, according to this purification method, the sulfur compounds that are originally contained in industrial butane and usually cause bad odors can be eliminated to 0.01pp+n or less, so the high purity butane component obtained can be used for aerosol cans. It is suitable as a propellant.

<Effects of the Invention> The present invention has an object of separating a raw material gas containing impure components into a target component and an impure component using selective adsorption, using a component detector and a switching valve interlocked therewith.

(1) By utilizing selective adsorption by a developing agent and passing the raw material gas through it, each component in the raw material gas is separated based on the difference in development speed, so the purity of the extracted target component can be extremely high. .

In other words, although separation by condensation and liquefaction, which is a conventional separation and purification method, can be applied to mixed gases containing large amounts of each component, it is difficult to apply to raw gas containing trace amounts of impure components. However, since impurity components are removed through a neutral reaction, it cannot be applied to all raw material gases, and there is also a limit to the solubility of impurity component gases, so it is not suitable for removing trace impurities.

However, in this purification method, the raw material gas is chemically adsorbed on the developer and developed, so even trace components can be developed accurately and it can be applied to all kinds of raw material gases.

(2) In this purification method, a component detector is used to track and confirm the target component and impure components that are developed and separated in a separation column, and a switching valve linked to this detector allows automatic capture of only the target component. Therefore, it is easy to take out the target component, and by automating the purification of the raw material gas, it is possible to quickly and easily take out the high-purity component.

(3) This shows that the present purification method can be applied to other than the dissolved acetylene gas in the above example.

For example, industrial liquefied carbonic acid contains odor components such as sulfur compounds as impurities, so if these purification methods remove impure odor components and obtain highly pure carbon dioxide gas, this can be used to make carbonated drinks. Can be used.

In addition, industrially supplied monosilane gas contains pyrophoric disilane as an impurity component, so if this purification method removes the disilane component and obtains high-purity moasilane gas, high-quality silicon Not only can semiconductors be easily manufactured, but the danger of fire can be smoothly eliminated. 6 Sarishiko contains industrial propane. Nakashiko contains paraffin components such as 7yn, ethane, and methane, and sulfur compounds as impurity components. 1-, so if this purification method removes impurity components and obtains high-purity propane, Experimental Example 2
As mentioned above, it can be applied to a propellant agent for aerosol cans to obtain the specified injection pressure, and it also provides odorless propane by eliminating sulfur compounds, so it has added value as a propellant agent. can be increased.

[Brief explanation of the drawing]

1 to 8 are schematic diagrams of a purification apparatus showing each step of the present purification method, and FIG. 9 is a chromatogram when raw material acetylene gas is purified and separated. 1... Raw material gas supply device, 6... Separation device, 7/8
Separation tower, 22... Switching valve, 24... Component detector, 25... Impure component discharge path, 28, 30... Target component capture device.

Claims (1)

[Claims] 1. In a gas purification method in which a raw material gas is supplied from a raw material gas supply device 1 to a separation device 6, and a target component is separated and taken out from the raw material gas in the separation device 6, a separation column filled with a developing agent is used. 7
(8), impurity component discharge path 25 and target component capture device 28 (
30) constitutes a separation device 6, and a switching valve 22 interlocked with a component detector 24 is arranged on the downstream side of the separation column 7 (8),
The downstream side of the switching valve 22 is branched and one side is connected to the trap 28 (30
), and the other end is connected to the impurity component discharge path 25, and the raw material gas is supplied all at once from the raw material gas supply device 1 to the developer type separation column 7 (8), and the raw material gas is connected in the developer type separation column 7 (8). The raw material gas is expanded, and the preceding impurity component preceding the target component, the target component, and the subsequent impurity component following the target component are sequentially flowed out, and when the detector 24 detects the preceding impurity component and the subsequent impurity component, the switching valve 22 is switched to the impure component discharge path 25 to discharge the impure component from the discharge path 25, and if the target component is detected by the detector 24, the switching valve 22 is switched to the trap 28 (30) to capture the target component. A gas purification method 2 characterized in that the target component is captured in a vessel 28 (30) and the target component is taken out from the target component trap 28 (30).
), and when capturing the target component, the target component capture device 28
(30) Cool the inside of the target component capture device 28 with a cooling means.
(30), while leaving the carrier gas mixed in with the target component as a gas, and while this carrier gas flows out of the target component trap 28 (30), the solidified target component is removed from the trap. After being stored in the target component trap 28 (30), the target component trap 28 (30) is heated by a heating means to turn the solidified target component into a gaseous state and taken out from the trap 28 (30). In the gas purification method 3 as set forth in claim 1, a plurality of separation columns 7 (8) are provided, a carrier gas is supplied to one of the plurality of separation columns 7 (8), and this After the raw material gas is developed in the separation tower 7 (8), the carrier gas flowing out from the trap 7 (8) when capturing the target component is transferred to the separation tower 7 (8) other than the one that is performing the development separation operation. Claim 1 or 2, characterized in that the separation column 7 (8) is regenerated with a carrier gas by passing through the separation column 7 (8).
Gas purification equipment described in section