JPH0226640A - Adsorbent and method for diluting gas concentration - Google Patents

Abstract

PURPOSE:To permit a solid adsorbent to be handled as a liquid without impairing its adsorptive characteristics by suspending said solid adsorbent in the liquid. CONSTITUTION:A solid adsorbent such as zeolite and molecular sieve carbon is suspended in a liquid such as silicone oil. This liquid is made more difficultly adsorbable by the solid adsorbent than a separably recovered gas (e.g., ammonia, various hydrocarbon gases and tricholrofluoromethane). The solid adsorbent has a particle diameter of not more than 500mum. A dilute gas is concentrated and recovered from the adsorbent resulting from the suspension of the solid adsorbent in the liquid in a distilling column consenser 15 by making the pressure of the dilute gas lower or the temperature thereof higher after collection in a collection column 1 than at the time of the collection. Such adsorbent permits the collection of the separably recovered gas in a large amount, resulting in an efficient recovery thereof in a short time by a simple continuous method.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an absorbent and a method for concentrating a dilute gas using the absorbent.

(Prior art and problems to be solved by the invention) As a method for separating and recovering gas or concentrating dilute gas, a solid adsorbent is used to absorb and absorb by swinging the pressure or temperature.
Methods of desorption and methods of absorbing and expelling by swinging the pressure or temperature using an absorbing liquid are known.

When using a solid adsorbent, you can either switch the gas flow and change the pressure and temperature conditions to achieve the adsorption/desorption conditions for multiple fixed beds of adsorbents, or continuously apply powder adsorbent. It is common to operate so that the adsorption/desorption area is circulated. However, the former case has the disadvantage that the fixed bed capacity is large and the switching operation between adsorption and desorption is complicated. In the latter case, it is necessary to move the powder in a fluidized bed or a moving bed, or to circulate it between them.
It may cause powdering.

There are many problems in actual operation due to clogging, and the adsorbent also needs to have physical properties that are difficult to powder and easy to flow.
There are many restrictions.

When using an absorbing liquid, the partial pressure of the absorbent under the absorption operating conditions must be low because the absorbent having the same property as the exhaust gas will be lost during absorption.

Of course, the amount of absorbed gas changes depending on the pressure and temperature, and the difference must be practical or stable.

There are many conditions and it may be difficult to find an absorption liquid suitable for the gas to be absorbed.

(Means for Solving the Problems) The present invention has been made to solve the above-mentioned problems, and is an absorption method for separating and recovering gas, which is characterized by suspending a solid adsorbent in a liquid. The present invention provides an absorbent (hereinafter simply referred to as the absorbent of the present invention) and a method of concentrating a dilute gas using the absorbent. The details will be explained below.

Taking advantage of the properties of solid adsorbents, we can achieve a simple continuous adsorption/desorption system by suspending the solid adsorbent in a liquid, without impairing the adsorption properties of the solid adsorbent. Moreover, it can be handled as a fluid.

Solid adsorbents are suspended in a liquid and can be treated as a fluid, and if they are easy to handle as a slurry, they can be in the form of granules,
Particle size is 500 to 100 without any limitation such as lumpy or fibrous
JL or less, preferably 5 (1g or less, more preferably 10JL or less), the solid adsorbent may be selected from activated carbon, especially moncular sieve carbon, zeolite, silica gel, alumina, etc., or composites thereof. The adsorption power of the liquid is preferably smaller than the adsorption power of the gas to be separated and recovered by the absorbent of the present invention (hereinafter simply referred to as recovered gas), or the adsorption power of the liquid is preferably one that does not substantially dissolve in the liquid. It is appropriate that the solid adsorbent has an adsorption pore size that does not adsorb the gas.Furthermore, although the liquid used has the role of a carrier for the solid adsorbent, it is appropriate that the liquid used does not interfere with the adsorption of the recovered gas onto the solid adsorbent. It is preferable to select the adsorption of the recovered gas and liquid onto the solid adsorbent □.
For example, if the molecular diameter of the liquid is 20 and the molecular diameter of the recovered gas is 5, an adsorbent with a pore size in the range of 5 to 20 should be used, or an adsorbent between the recovered gas and the liquid should be used. It can be obtained by selecting a liquid that has polarity or not, or has a polarity of strength or weakness.

When a dilute gas is collected using the absorbent of the present invention, the remaining inert gas after the collected gas is collected and removed is discharged as a gas having a concentration equivalent to the vapor pressure of the liquid. If the vapor pressure of the liquid is high.

Even if it is discharged at a temperature as low as possible, it is a liquid with an inherently low vapor pressure, that is, a partial pressure at room temperature of 10X 1G-”~
IOX 10-coTO "The following is preferable.

Specific types of liquids include fluorine oils such as tetrafluoroethylene-based, chlorotrifluoroethylene-based, perfluorocarbon-based, and perfluoropolyether-based oils, and silicone oils such as dimethylsiloxane and diphenylsiloxane.

Or fluorosilicone oil or polyolefin type,
These include hydrocarbon oils such as polyether-based, carboxylic ester-based, and phosphoric ester-based oils.

Methods for separating the gas trapped by the absorbent of the present invention from the absorbent include recovering hot air using a heated inert gas (e.g., nitrogen gas, air, etc.) or separating the collected gas and liquid by distillation. Of course, it is sufficient to adopt a method of separating by raising the temperature to a higher temperature than at the time of collection, or a method of separating by lowering the pressure to a lower pressure than at the time of collection, such as collecting under reduced pressure using a vacuum pump etc. Of course, these methods may be used. By passing through such separation means, which may be used in combination, the collected dilute solution can be concentrated. In this case, in addition to concentrating a single gas, if a selective adsorbent is used as a solid adsorbent, it is also possible to concentrate only a specific component in a mixed gas.1 The gas collected by the absorbent of the present invention is Most of the gas is adsorbed on the solid adsorbent in the absorbent, but it may be partially absorbed in the liquid, and the absorbed gas can be recovered by distillation or the like.

The gas to be separated and recovered by the absorbent of the present invention, or the gas to be concentrated by separation after being collected by the absorbent of the present invention, is more easily adsorbed by the solid adsorbent than the liquid in the absorbent, and is desorbed by the absorbent. If possible, without any limitation, ammonia, hydrogen sulfide, sulfur dioxide gas, various hydrocarbon gases, chlorine compounds such as trichlorethylene, perchlorethylene, methylene chloride, methyl chloroform, trichlorofluoromethane, dichlorodifluoromethane, chlorodifluoro Examples include chlorinated fluorinated compounds such as methane, tetrachloro-1,2-difluoroethane, 1,1.2-)lichlorotrifluoroethane, and 1,2-dichlorotetrafluoroethane.

An example of a method for concentrating a dilute gas using the absorbent of the present invention will be explained below with reference to FIG.

In the figure, 1 is a collection column, 2 is a distillation column, 3 is a liquid pump after collection,
4 is a liquid pump after discharge, 5 is a collection tower supply cooler, 6 is a raw material diluted gas supply line, 7 is an exhaust gas line after removal of the collected gas, and 8 is a liquid line for the absorbent containing the collected gas (distillation 9 is the liquid line after discharge (absorption column feed liquid line), 10 is the collection gas collection line, 1 is the concentrated gas line, 12 is the reflux liquid line, 13 is the distillation column reboiler,
] 4 is a raw material diluted gas feeding fan, and 15 is a distillation column condenser.

The raw material diluted gas passes through line 6 and is blown to 1 by 14 blowers.
Flows from the bottom of the collection tower to the top of the tower.

- The absorbent invented by Rikiki is cooled to a predetermined temperature in the cooler 5, is supplied to the top of the column 1 through the line 9, and flows down to the bottom of 1, where it comes into contact with the diluted gas from the bottom in an alternating current manner. It is mainly adsorbed on the scavenging gas and the solid adsorbent in the absorbent of the present invention. The adsorbent containing the solid adsorbent that has adsorbed the collected gas is supplied to the top of the distillation column recovery section 16 through the line 8 and the pump 3 to gasify the collected gas. The released gas is rectified in the rectification section 17 of the distillation column, passes through line 10, and is fractionated in a condenser 15. The condensate is returned to the top of the rectification section through line 12, and the collected gas is It is taken out as a concentrated gas through line 11. The absorbent containing the solid adsorbent that has desorbed the collected gas is circulated through line 9 and pump 4 to the top of the collection column.

[Example] Silicone oil (Shin-Etsu Silicon Co., Ltd. KF) as a liquid
-98-50C3) and activated carbon [
Osaka Gas Co., Ltd. manufactured fiber female activated carbon pulverized product (particle type approx. 30
0μ)] at the mixing ratio shown in Table 1. Add 1, 1.
2-Trichlorotrifluoroethane (hereinafter referred to as R-113) was adjusted to the values shown in Table 1, mixed in a sealed container, and the content of R-113 in the gas phase was measured. The results are shown in Table 1. R-113 was added to 1 kg of R-113-free absorbent of sample number 1 at room temperature at 1100%
R-113 was absorbed through a gas containing 0 pp. The R-113 concentration in the obtained absorbent was 0.85 wt%. R-1
13 were recovered. The concentration of R-113 in the obtained gas was 3
5% by volume, and the amount recovered was about 6g. In addition, the R-113 concentration in the absorbent obtained when performing the same operation using a comparative example absorbent that does not contain activated carbon was O.10 wt%.
The concentration of the recovered gas was 32% by volume, and the amount recovered was about 1 g.

Table 1 [Effects of the invention] The absorbent of the present invention, which is made by suspending a solid adsorbent in a liquid, has the following properties:
Since a very large amount of gas to be separated and recovered can be collected, efficient recovery is possible in a short period of time. Furthermore, since the absorbent of the present invention can be handled as a liquid using an adsorption/desorption system, it can be separated and recovered using a simple continuous system.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a method for concentrating dilute gas using the absorbent of the present invention. DESCRIPTION OF SYMBOLS 1... Collection column, 2... Distillation column, 5... Collection column feed liquid cooler, 15... Distillation column condenser

Claims (1)

[Claims] 1. An absorbent for separating and recovering gas, characterized in that it is made by suspending a solid adsorbent in a liquid. 2. The absorbent according to claim 1, wherein the liquid is less easily adsorbed by the solid adsorbent than the gas to be separated and recovered. 3.Claim 1, wherein the solid adsorbent has a particle size of 500μ or less.
Absorbent as described. 4. After collecting the diluted gas in an absorbent made by suspending a solid adsorbent in a liquid, the diluted gas is concentrated and separated from the absorbent by applying a lower pressure or higher temperature than during collection. A method for concentrating dilute gas.