JPH062682B2 - Acetylene purification method and apparatus used therefor - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for purifying acetylene and an apparatus used therefor.

[Conventional technology]

Conventionally, acetylene has been used as a raw material in the field of acetylene welding and the chemical industry.

Acetylene, which is used as a raw material in the field of acetylene welding and chemical industry, is manufactured from carbide and petroleum as raw materials, and it is harmful to the human body or used for welding from crude carbide acetylene or petroleum acetylene immediately after production. PH ₃ , H ₂ S, which reduces the strength in case of
NH ₃ , ASH _3, etc., and O ₂ , PH ₃ , H _{2 which} are catalytic poisons for chemical reactions
Purified to a purity of 98% by volume or higher, as specified in JIS K 1901 and 1902, by removing S, etc.

For example, if the normal commercial carbide dissolution acetylene was raw material, acetylene has been contained from 98.0 to 99.5 volume%, such as N _2, O _2, Ar is an impurity from the air is mixed as the main impurity , NH due to other raw materials
₃ , PH ₃ , H ₂ S, H ₂ , CH _4, etc. are mixed as impurities. As an example of measurement data of the gas composition of dissolved acetylene at the Osaka Environmental Technology Center, acetylene 99.45% by volume, H ₂ 0.01% by volume, N ₂ 0.2844% by volume, O ₂ 0.0756% by volume, CO less than 0.01% by volume, CO ₂ 0.01% Less than% by volume, CH ₄ 0.1
Results of 3% by volume have been reported. Further, in the case of commercially available petroleum acetylene using petroleum as a raw material, the recovered acetylene contains about 99.5% by volume, and contains C ₂ H ₄ and CO ₂ as impurities.

With the recent technological progress, new materials have come to be produced from acetylene as a raw material.

For example, acetylene has come to be used as a raw material for a conductive organic substance such as polyacetylene and a photosensitive organic substance such as an acetylene derivative. It is also used as a carbon source for high-purity carbides as a functional material called fine ceramics, or as a raw material when producing a-SiC: H with high solar conversion efficiency, which is often used as a window-side semiconductor for solar cells. As such, highly reactive acetylene has come to be used.

In order to obtain the properties required for these new materials, it is necessary to strictly control the composition of the new materials, and acetylene as a raw material for them is required to have high purity. .

[Problems to be solved by the invention]

As a method to obtain purified acetylene for use in the production of new materials, acetylene is cooled to about -150 ° C or lower in a liquefied nitrogen bath to form solid acetylene, and the vapor phase component is evacuated to sufficiently remove the vapor component. There is a method suitable for research on a small scale, in which it is then evaporated to obtain purified acetylene, but if the pressure exceeds 1.4 kg / cm ² abs., There is a risk of decomposition and explosion, which is necessary for industrial use. The quantity cannot be supplied safely and economically.

The present invention has been made for the purpose of obtaining a safe and industrially necessary amount of purified acetylene.

[Means for solving problems]

The present invention absorbs acetylene in a solvent which selectively absorbs acetylene, and diffuses or recovers it batchwise or continuously by utilizing the difference in the amount of dissolution due to the temperature difference, at the time of producing purified acetylene, at a solvent temperature of -20 After absorbing acetylene at ~ -81.8 ° C, the temperature is raised to -10 ~ + 20 ° C and the diffused acetylene is -50
Re-cooling to ~ -81.8 ° C to condense solvent etc., and further remove coexisting solvent etc. by adsorption by passing through porous material filling section, purification of acetylene characterized by purity of 99.99% by volume or more Method, and an acetylene absorption tower that absorbs acetylene in a solvent that selectively absorbs acetylene at -20 to -81.8 ° C, an acetylene diffusion tower that diffuses acetylene that has been absorbed in a solvent that selectively absorbs acetylene at -10 to + 20 ° C, 50 acetylene that has been diffused
To a cooling tower for re-cooling to -81.8 ° C and an adsorption tower filled with a porous substance for removing impurities in the cooled acetylene, and the acetylene diffusion tower for absorbing the solvent in which the acetylene is absorbed in the acetylene absorption tower. And a means for returning the solvent in which acetylene is diffused in the acetylene stripping tower from the acetylene diffusion tower to the acetylene absorption tower.

〔Example〕

In the present invention, a solvent which selectively absorbs acetylene (hereinafter, referred to as an acetylene absorbing solvent) absorbs acetylene, and the purified acetylene is obtained by releasing the acetylene batchwise or continuously by utilizing the difference in the amount of dissolution due to the temperature difference. To be done.

Acetylene that can be absorbed in an acetylene absorbing solvent may be coarse acetylene produced by decomposing carbide or petroleum, and PH ₃ , H ₂ S, NH ₃ , A _S H ₃ etc. are removed to JIS K Acetylene purified to comply with the regulations of 1901 and 1902 may be used.In order to reduce the risk of decomposition and explosion of acetylene when transporting it, put it in a container containing a substance impregnated with a porous substance in a solvent. Dissolved acetylene may be dissolved and is not limited by its purity, raw material, or the like. However, from the viewpoint that purified acetylene can be efficiently obtained, in the case of carbide acetylene, pretreatment by a liquid acetylene purification method such as Japanese Patent No. 203622 (a method using an apparatus called "Exisei") is used. It is preferable that

Purified acetylene as used herein means that the total amount of impurities is 10
Means: acetylene 0 ppm, such as H ₂ less than _{0.5ppm, O 2 1.0~2.5ppm, N 2} 1.0~2.5ppm, CO 0.5ppm or less, CO ₂ 1.0 ppm or less, PH _3, both AsH ₃ and solvents The composition is such that it is not detected (0.1 ppm detection limit).

The temperature when absorbing the acetylene in the solvent,
Increases the amount and rate of dissolution and does not liquefy acetylene (liquefaction temperature of acetylene-81.8 ℃, 760mmH
From the viewpoint of economical absorption in g), it is necessary to be -20 to -81.8 ° C, preferably -40 to -60 ° C. If the absorption temperature exceeds -20 ° C, only acetylene with a purity of about 99.9% by volume can be obtained.

The pressure for absorbing the acetylene in the solvent is not particularly limited as long as it is 7.0 kg / cm ² abs. Or less, which is less likely to cause decomposition and explosion of acetylene when coexisting with the solvent. The range naturally depends on the source. For example, in the case of carbide acetylene or petroleum acetylene, about 1.02 to 1.5 kg / cm ² · abs., And in the case of dissolved acetylene, 1.2 to 1.5 kg / cm ² · ab.
It is common to use the pressure regulator to reduce the pressure to about s.

The acetylene absorbing solvent exists as a liquid under the conditions as described above, selectively absorbs acetylene, and acetylene can be purified by releasing acetylene at -10 to + 20 ° C, preferably -5 to + 10 ° C. There is no particular limitation as long as it is a solvent that does not react with. Specific examples of such a solvent include acetone, which has high selective absorption of acetylene, N, N-dimethylformamide (DMF), N-methylpyrrolidone, and the like, and these may be used alone,
You may use 2 or more types together.

It should be noted that selective absorption of acetylene means that there is a significant difference in solubility between acetylene and O ₂ , N ₂ , CO, H _{2 and the} like existing as impurities. For example, for DMF, the solubility is significant as shown in Table 1. It means that there is a difference, and that acetylene is released means that at least 1 acetylene of the absorbed acetylene per solvent is about 70 in the standard state.
It means that the above is emitted at -10 to + 20 ° C. DMF
About 238 of acetylene is absorbed at -40 ° C in the standard state and about 382 of 382 at -60 ° C in the standard state.

The temperature at which the acetylene absorbed by the solvent is released is -10 to +
In the case of 20 ° C., there is a large difference in solubility due to the temperature difference from the time of absorption, so the recovery efficiency is high and this is economically preferable. Particularly, from the viewpoint of heat energy efficiency, about -10 to 0 ° C is preferable, and from the viewpoint of the amount of acetylene purified, -5 to + 10 ° C is preferable.

In addition, the pressure of acetylene at the time of emission does not suck air when handled only with pure acetylene, and decomposition does not propagate even if incorrect ignitable energy is applied.
It is preferably 1.0 to 1.2 kg / cm ² · ads.

Since the solvent used for purification is mixed in the acetylene thus purified, acetylene does not liquefy,
Moreover, it is cooled to -50 to -81.8 ° C in order to reduce the content of the above-mentioned coexisting solvent as much as possible, and is passed through the porous material filling part to adsorb and remove the solvent and its condensate.

The porous material-filled part is made of activated carbon, molecular sieve, silica gel, etc. and has a pore size of about 5Å.
It is like putting a porous body of about 14 mesh in a usual coolable packed tower placed in, for example, a cylindrical tube.

The amount of acetylene passed through the porous material filling part and the residence time may be appropriately selected in consideration of the purity and the purification efficiency of acetylene, etc., but usually used per unit volume of the porous adsorbent, It is appropriate that the adsorbed gas volume is 10,000 times or less per hour.

By such a method, for example, 98 to 99.5% by volume of acetylene can be purified to about 99.99 to 99.9999% by volume.

The purified acetylene may be used as it is, may be filled in a cylinder or the like, and the method of the present invention may be applied again for further purification to obtain purified acetylene such as 9 ⁷ (seven nine) or more that has not been obtained in the past. You can get it.

The method of the present invention may be a batchwise method in which absorption and desorption of acetylene are carried out in the same tank as shown in FIG. 2, and as shown in FIG. 1, acetylene is used in one tank. May be carried out, and the solvent in which acetylene has been absorbed is continuously transferred to another tank, and acetylene can be released in this other tank.

Next, the method of the present invention will be described with reference to FIG.

(Absorption process) 1 Cool the acetylene absorption solvent (2) in the acetylene absorption tower (1) in the cooling tank (6) to -20 to -81.8 ° C, and then cool the acetylene absorption tower.
The acetylene absorbing solvent (2) in (1) absorbs acetylene. Also, when acetylene is absorbed, it generates heat,
The cooling tank (6) removes this heat and keeps the temperature of the acetylene absorbing solvent (2) at a predetermined temperature of -20 to -81.8 ° C.

The acetylene is sucked in at a portion near the bottom of the acetylene absorption tower (1), and the acetylene is absorbed when rising in the acetylene absorbing solvent (2).

2 As the acetylene absorbing solvent (2), one that dissolves acetylene is used, and it contains O ₂ , N ₂ , CO,
Most of the impurity gas such as H ₂ is not absorbed by the acetylene absorption solvent (2) and accumulates in the upper part of the acetylene absorption tower (1). This is discharged from the discharge port (10) by operating the discharge valve (11) together with a part of acetylene.

3 To cool the acetylene absorption solvent (2), dry ice is added to methanol in the cooling tank (6), or liquefied nitrogen is added dropwise to the ethylene glycol aqueous solution to form a cooled low-temperature liquid, and the acetylene absorption tower (1) It may be cooled through the wall of the above, or a cooling pipe may be installed in the acetylene absorption tower (1), and the above-mentioned low temperature liquid may be passed through the cooling pipe for cooling.

The acetylene-absorption solvent (2) that has sufficiently absorbed and dissolved acetylene at 4 -20 to -81.8 ° C does not mix the impurity gas existing in the upper gas phase of the acetylene absorption tower (1) with, for example, the acetylene-absorption solvent (2). The pressure in the acetylene absorption tower (1)> the pressure in the acetylene absorption tower (3), using the pipe that reaches the lower part of the liquid and a means consisting of a metering pump (9), or the pipe and the flow rate adjustment valve. It is transferred into the acetylene stripping tower (3) by using the above-mentioned means.

(Dissipation process) 1 Acetylene absorption solvent (2) transferred to acetylene dispersal tower (3) is heated to the range of about -10 to + 20 ° C, and acetylene corresponding to the difference in solubility of acetylene caused by this temperature difference. Are released from the acetylene absorbing solvent (2).

2 Part of the solvent used for the heating method of the acetylene absorbing solvent is acetylene absorbing solvent and acetylene absorbing solvent at -20 to -81.8 ° C introduced from the acetylene absorbing tower (1) into the acetylene releasing tower (3). In the acetylene diffusion tower (3), the acetylene absorption solvent returned to the acetylene absorption tower that was sucked up by the metering pump (8) from the acetylene that had diffused to -10 to + 20 ° C in the bottom liquid reservoir of the tower (3) If a heat exchange part is provided on the upper part of the above, and if necessary heat is exchanged together with a filler, etc., the efficiency of heat exchange between cooling of the solvent after being diffused and heating of the acetylene absorbing solvent to be introduced is improved. Is preferred.

3 It is important from the standpoint of safety that the acetylene is released from the acetylene absorbing solvent gradually and steadily in order to suppress the rise in internal pressure, and it is efficient in terms of thermo-economics. This heat exchange is performed in the acetylene stripping tower (3), and the acetylene released by the temperature rise of the acetylene absorbing solvent (2) is recovered via the cooling tower (4) and the adsorption tower (5).

4 Preferably, the acetylene absorbing solvent accumulated at the bottom via the heat exchange section provided at the upper part of the acetylene stripping tower is, if necessary, a non-freezing liquid such as 10% ethylene glycol liquid for heat exchange for heating. Heat is exchanged through the vessel (15), the temperature is raised to a predetermined temperature of -10 to + 20 ° C, and acetylene is diffused.

5 From the pipe that reaches the bottom of the liquid storage part of the acetylene stripping tower (3), most of the acetylene-dissipating part of the acetylene-absorbing solvent is sucked up by the metering pump (8), preferably the acetylene-absorbing via the heat exchange part. The upper part of the tower (1), preferably introduced into the upper part where the packing is filled to improve cooling efficiency, the acetylene absorbing solvent (2) in the acetylene absorption tower (1)
Keeping the amount of a certain amount constant so that the absorption process and the emission process can be performed continuously.

(Solvent vapor removal step) Acetylene that has been emitted by acetylene emission, etc. (3) contains approximately 30-180 ppm of solvent vapor, so the acetylene is cooled in the cooling tank (7) at -50 to -81.8 ° C. Cooling tower during cooling
(4), and preferably lead to a cooling tower (4) which is filled with a fine wire such as silica gel or SUS to improve cooling efficiency, and removes solvent vapor contained therein. Furthermore, in order to remove solvent vapors in acetylene more completely, an adsorption tower filled with a porous material such as activated carbon, molecular sieves and silica gel and cooled to -50 to -81.8 ° C.
(5) is passed.

It is preferable that two sets of the cooling tower (4) and the adsorption tower (5) are provided in parallel so that they can be switched.

By the above-mentioned procedure, about 55 to 650 acetylene can be purified per standard acetylene absorbing solvent.

The obtained acetylene is 99.99 to 99.9999% by volume of purified acetylene.

The cooling tower and the adsorption tower are not particularly limited as long as they can efficiently cool to -50 to -81.8 ° C and can collect the solvent vapor in the gas, for example, ethylene glycol or methanol. It is cooled by a method such as dropping dry ice or liquid nitrogen onto the.

In the above description, the method for producing purified acetylene by the continuous method has been described, but high-purity acetylene can be similarly produced by using a batch type apparatus as shown in FIG.

When an apparatus as shown in FIG. 2 is used, the acetylene absorbing solvent (2) in the acetylene absorption separation column (12) is cooled by the temperature control pipe (13) to absorb acetylene, or While absorbing, the impurity gas on the acetylene absorbing solvent and acetylene are discharged from the discharge port (10) by operating the valve (11), and further the vacuum pump (14).
And the impurity gas in the gas phase is removed. Then, the temperature of the acetylene absorbing solvent which has absorbed acetylene is raised by the temperature control pipe (13), and the acetylene thus diffused is passed through the cooling tower (4) and the adsorption tower (5) to obtain purified acetylene.

Next, the method and apparatus of the present invention will be described based on examples.

Example 1 An apparatus as shown in FIG. 1 was used.

The acetylene absorption tower has a diameter of 10 cm, a height of 50 cm, and an internal volume of 3925 cm.
^In the cylindrical stainless steel column of 3, the opening of the acetylene blowing line, the opening of the line for returning the acetylene absorbing solvent from the acetylene stripping tower and the opening of the line for sending the acetylene stripping tower hair acetylene absorbing solvent are 1 cm from the bottom, respectively. It was at 49 cm and 11 cm. The acetylene stripping tower has a diameter of 10 cm, a height of 50 cm, and an internal volume of 3925 cm ^3.
In the cylindrical stainless steel column of No. 3, the opening of the line for sending the acetylene absorbing solvent from the acetylene absorption tower and the opening of the line for returning the acetylene absorbing solvent to the acetylene absorption tower were located 49 cm and 1 cm from the bottom, respectively. Further, the cooling tower is a stainless steel tower having a diameter of 2.5 cm and a height of 50 cm that is filled with silica gel, and the adsorption tower has a diameter of 2.5 cm and a height of 50 cm that is filled with activated carbon. It was a stainless steel tower.

Put 500 ml of DMF, which is the acetylene absorbing solvent, into the acetylene absorption tower and the acetylene stripping tower, and apply a pressure of 0.5 kg / c
m ² G, flow rate 500 / hr Suction of acetylene, and 50 minutes later, acetylene absorption tower internal pressure> acetylene diffusion tower internal pressure became steady, so the solvent that absorbed acetylene from the acetylene absorption tower to the acetylene diffusion tower was a small flow rate control valve Through 55
The valve was opened for quantitative flow at ml / min. In addition, the acetylene absorbing solvent from which acetylene was diffused from the acetylene stripping tower to the acetylene absorbing tower was returned by a metering pump at 40 ml / min.

To cool the acetylene absorption tower, cool the refrigerant in the cooling tank (6) to -60 ° C and add 0.5 kg / cm ² G of acetylene in the molten acetylene container.
When the pressure was reduced to 500 ° C. and absorbed at a rate of 500 / hr, the liquid was cooled to about −50 ° C. in the upper liquid of the acetylene absorption tower.

The dissolution rate of acetylene is very fast, almost all acetylene is dissolved in the first about 50 minutes, and the discharge valve (11) is adjusted so that the internal pressure of the acetylene absorption tower becomes 0.2 kg / cm ² G.
The extra gas, which was boosted in pressure, was released into the atmosphere through an integrating flowmeter.

The acetylene absorbing solvent of about -50 ° C sent to the acetylene stripping tower is a 10% aqueous solution of methanol (liquid temperature: 10% in the acetylene stripping tower so that the temperature at the time of returning to the acetylene absorbing tower from the upper part of the tower is about 0 ° C). (About 15 ° C) to heat the mixture, and at that time, the acetylene released is added as a refrigerant to dry ice added to methanol and sent to a cooling tower cooled to -75 ° C to condense and remove the solvent vapor contained in it. Purified acetylene was obtained through the adsorption tower.

The obtained purified acetylene was the result of analysis using Shimadzu GC9A type gas chromatograph TCD and FID automatic switching detector,
N ₂ 3ppm or less, O ₂ 2ppm, CO ₂ 3p at the detection limit of 3.0ppm
CO is not detected below pm and P at the detection limit of 1.0 ppm
It was purified acetylene with a purity of 99.999% in which H ₃ , H ₂ S, and AsH ₃ were not detected.

The amount of acetylene purified after reaching steady state is 425.
/ Hr (standard state), and the yield based on the starting acetylene was 85%.

Example 2 An apparatus as shown in FIG. 2 was used.

The acetylene absorption and diffusion tower has a diameter of 10 cm, a height of 50 cm, and an internal volume of 39.
This is a 25 cm ³ cylindrical steel tower with a temperature control tube attached to the part where the acetylene absorbing solvent enters, and the opening of the acetylene blowing line is located 1 cm from the bottom of the acetylene absorbing / dissipating tower. It was As a cooling tower and an adsorption tower, a stainless steel tower having a 2.5 cm diameter and a height of 30 cm and filled with activated carbon was used.
Those connected in series were used.

Acetylene absorption solvent DMF which is an acetylene absorption solvent
Put 1, while cooling in DMF to be -50 ° C. using a _{coolant, NH 3, H 2 S,} PH 3, a pressure dissolution acetylene removal AsH ₃ and the pretreatment through the "humoral" It was blown with 0.5 kg / cm ² G at a flow rate of 300 / hr. At this time, the pressure of the gas phase in the acetylene absorption and diffusion tower was set to 0.2 kg / cm ² G.
The valve (11) was adjusted so that it was maintained at 1, and the extra pressure-enhanced gas was discharged into the atmosphere through the integrating flow meter.

When acetylene was blown in for about 1 hour, the acetylene absorbing solvent was almost saturated. Since a large amount of impurity gas in acetylene, which is difficult to be absorbed by the acetylene absorbent, is accumulated in the gas phase part of the acetylene absorption / desorption tower, in order to remove it, the acetylene absorption solvent is further cooled to about -60 ° C and then the vacuum pump is used. Vacuum was evacuated using (14) to 10 ^-1 Torr.
Continuously, injection of high-purity Ar and evacuation were repeated 10 times to exhaust gas phase impurity gas. After that, the acetylene absorbing solvent was emptied from the temperature control tube and gradually heated to release the dissolved acetylene.

Purified acetylene was obtained from the acetylene obtained by stripping through a two-stage adsorption tower cooled to about -75 ° C using a cooling tank in which dry ice was added to methanol as a refrigerant.

The obtained purified acetylene is the result of analysis using a Shimadzu GC9A type gas chromatograph TCD and an FID automatic switching analyzer,
Both the detection limit _{3ppm N 2, O 2, CO} 2, H 2 is 3ppm
Less than, detection limit 1ppm CO, PH ₃ , NH ₃ , AsH ₃ , H ₂ S
Was high-purity acetylene with a purity of 99.999%, which was not detected.

It takes 2 hours to purify acetylene per batch.
It was 180 (standard state), and the yield based on the raw material acetylene was about 60%.

〔The invention's effect〕

Not only high purity acetylene was not Shikae conventional laboratory scale according to the method of the present invention, the 9 ⁷ or more acetylene has not been e conventionally can sell economically on an industrial scale. Further, in the method of the present invention, since commercially available acetylene such as dissolved acetylene can be used as a raw material, the apparatus of the present invention is installed in a place where high-purity acetylene is used, and high-purity acetylene is produced by the method of the present invention. In addition, it is possible to reduce the transport ratio, prevent a decrease in purity that occurs in the case of cylinder filling, and purify and use a necessary amount of acetylene.

[Brief description of drawings]

FIG. 1 is an explanatory view of an embodiment of the apparatus of the present invention used in the method of the present invention, and FIG. 2 is an explanatory view of another embodiment of the apparatus of the present invention used in the method. (Main symbols in the drawing) (1): Acetylene absorption tower (2): Acetylene absorption solvent (3): Acetylene diffusion tower (4): Cooling tower (5): Adsorption tower

Front Page Continuation (72) Inventor Kenji Yamawaki 108-1 Hirai, Sakai City, Osaka (56) References Japanese Patent Publication No. 40-26893 (JP, B1) Japanese Patent Publication No. 37-4851 (JP, B1) Japanese Patent Publication No. 47 -19246 (JP, B1)

Claims (6)

[Claims] 1. A solvent which absorbs acetylene into a solvent which selectively absorbs acetylene, and diffuses or recovers the acetylene batchwise or continuously by utilizing the difference in the amount of dissolution due to a temperature difference to produce a purified acetylene at a solvent temperature- After absorbing acetylene at 20 to -81.8 ° C, raise the temperature to -10 to + 20 ° C and remove the emitted acetylene to -5.
A method for purifying acetylene, which comprises re-cooling to 0 to -81.8 ° C and further passing through a porous material-filled portion to obtain a purity of 99.99% by volume or more. 2. The purification method according to claim 1, wherein the solvent is acetone, N, N-dimethylformamide, N-methylpyrrolidone or a mixture thereof. 3. The pressure of acetylene at the time of absorption is 0.1 to 7.0.
The purification method according to claim 1, which is kg / cm ² · abs. 4. The pressure of acetylene during the emission is 0.1 to 1.4.
The purification method according to claim 1, which is kg / cm ² · abs. 5. The purification method according to claim 1, wherein the porous substance is activated carbon, molecular sieve or silica gel. 6. An acetylene absorption tower capable of absorbing acetylene in a solvent which selectively absorbs acetylene at -20 to -81.8 ° C., and acetylene diffusion which diffuses acetylene absorbed in a solvent which selectively absorbs acetylene at -10 to + 20 ° C. The acetylene absorption column consists of a column, a cooling column for re-cooling the diffused acetylene to -50 to -81.8 ° C., and an adsorption column filled with a porous material for removing impurities in the cooled acetylene. Means for sending the solvent that has absorbed acetylene to the acetylene stripping tower and means for returning the solvent that has stripped acetylene in the acetylene stripping tower from the acetylene stripping tower to the acetylene absorption tower is provided with acetylene Refining equipment.