JPS62254809A - Separation of water in organic solvent - Google Patents

Abstract

PURPOSE:To reduce the equipment and operating cost and to separate the water in an org. solvent by cooling the water-contg. org. solvent, and then passing the solvent through a porous sheet made of fluoroplastics. CONSTITUTION:An org. solvent such as pentane contg. water is cooled in a decanter 5 by a refrigerant passing through a cooling coil 4, and water is separated. Large particulate water is discharged from the lower part of the decanter 5, and the org. solvent contg. misty water overflows into the adjacent intermediate tank 6. The org. solvent stored in the intermediate tank 6 is transferred by a pump 1 from the bottom part, and passed through a filter 2 and then the porous sheet 3 made of fluoroplastics. The misty water is not passed through the sheet 3 with only the org. solvent passed, and hence water and the solvent are separated. The separated water is returned to the decanter 5. Meanwhile, the org. solvent is sent to a solvent tank 7 and recovered.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a method for separating water in organic solvents.

(Prior Art) Organic solvents are used in large quantities in various processes such as painting, printing, and cleaning. These organic solvents are generally recovered and reused from an economic standpoint.

Its recovery is usually distilled M! ! ! method, activated carbon adsorption method, etc. are used, but the recovered organic solvent generally contains water, and depending on the purpose of use, it may be necessary to remove such water. Fixed-bed dehydration equipment filled with adsorbents such as silica gel and zeolite is used to remove water from organic solvents, but this method requires high equipment costs for explosion-proofing of flammable solvents. However, inert gas and a large amount of heat are required to regenerate the adsorbent, resulting in high operating costs.

(Problems to be Solved by the Invention) An object of the present invention is to provide a method for separating water in an organic solvent by a method that is significantly inexpensive in terms of equipment costs and operating costs.

(Means for Solving the Problems) The present invention relates to a method for separating water in an organic solvent, which is characterized in that the organic solvent containing water is cooled and then passed through a porous sheet made of fluororesin.

The solubility of water in organic solvents rapidly decreases as the temperature decreases, and water with a solubility higher than the equilibrium solubility at the cooling temperature is separated into two types: large particle water and small mist water.

The former large particle water can be separated by gravity, but the latter mist water is cloudy and emulsified in fine particles, so normal gravity separation is impossible.

In the present invention, the organic solvent is cooled, and if the separated water contains large particulate water, it is separated by specific gravity, and then the organic solvent containing the water in the form of a mist is passed through a fluorine (oil-made porous sheet). The mist-like water does not pass through the porous sheet, but only the organic solvent passes through it, thereby making it possible to separate the mist-like water from the organic solvent.

The organic solvents targeted by the present invention are liquids that pass through the porous sheet made of the above-mentioned 7-carbon resin RR6, such as pentane, hexane, tecane, dodecane, cyclohexane, petroleum,
Hydrocarbons such as petroleum ether, solvent naphtha, benzene, toluene, xylene; chloroform, tX tetrachloride
, perchloroethylene, trichlorethylene, Guyfuron-113, Gui70 solvent) 33; halogenated hydrocarbons such as methanol, ethyl, propyl,
Alcohols such as butanol; Ketones such as acetone and methyl ethyl ketone; Ethers such as ethyl ether, methyl ethyl ether, trimethyl ether, and tetrahydro-7rane; Organics such as ethyl acrylate, butyl acrylate, methacrylic acid, acetic acid, and methyl acetate Acids and esters; Examples include amines such as diethylamine and triethylamine.

In the present invention, the cooling temperature of the organic solvent containing water is higher than the condensation temperature of the mixture of organic solvent and water and the solidification temperature of the mixture.

The porous sheet made of fluororesin used in the present invention may be, for example, one made of paper, cardboard, etc. using a powder of a tetrafluoroethylene polymer, dried and heat-treated, or one obtained by extruding a paste and rolling it. Examples include porous sheets made by stretching unfired films of tetrafluoroethylene polymers. Such porous sheets can be selected from a variety of types, but typically have a thickness of about 0.05 to 31 RIIl.
, porosity is approximately 40-85 vol%, maximum pore diameter is approximately 1-85 vol.
One with a pupil of 100μ is preferable.

An apparatus to which the water separation method of the present invention is applied will be described below. Figure 1 shows an apparatus used when the specific gravity of an organic solvent is lower than that of water.The organic solvent containing water is cooled in a decanter 5 by a refrigerant passed through a cooling coil 4, and the water is removed. To separate. Large particulate water is drained from the lower part of the decanter 5, and a mist of organic solvent containing water overflows into the adjacent intermediate tank 6.

The organic solvent stored in intermediate M6 is pumped from the bottom to pump 1.
After passing through filter 2, fluorine O (
It is passed through a porous oil sheet 3, where the mist-like water does not pass through the transfer sheet 3, but only the organic solvent passes, so that the two are separated. The separated water is returned to decanter 5,
On the other hand, the Ariso solvent is sent to the solvent M7 and recovered.

Figure 12 shows an apparatus used when the specific gravity of an organic solvent is greater than that of water, and Figure 2 shows an apparatus for draining, drying and washing articles using a solvent whose specific gravity is in this relationship. In FIG. 2, 8 is a solvent storage tank, 9 is a water separation tank, 10 is a draining tank, and 11 is a steam tank. The solvent used is, for example, Freon-113 (trichlorotriple olethane) or a small proportion (usually 10% or less) of a water-soluble solvent (ethanol, acetone, impropatol, etc.) to improve the drainage effect. It is a mixture of
Articles to which water has adhered due to washing are immersed in a draining tank 10 to remove adhering water and at the same time to perform solvent cleaning. The solvent in the draining tank 10 overflows the partition wall while containing the water released from the surface of the article and enters the adjacent moisture #l tank 9, where most of the water rises to the surface due to the difference in specific gravity, forming a layer of water on the surface. make. This water is discharged from the ice outlet 12 through the discharge pipe 1.
3 and is discharged out of the system. However, as a solvent, Freon-
If water-soluble liquid is used in addition to 113, this waste water contains a large amount of water-soluble solvent, so in this case, the waste water is subjected to distillation to recover the water-soluble liquid. It is necessary to return it to the system. If this return fabrication is not performed, the water-soluble liquid is lost to the outside of the system along with the water, and the concentration composition of the solvent system immediately collapses, making it impossible to maintain the stability of the system.

As the treatment time progresses, water gradually dissolves into the solution, and as the water content of the solution in the device increases, the draining and cleaning effects decrease. Therefore, in order to reduce the solubility of water in the water draining tank, Ariiso Youtai is cooled in the water separation tank 9 and the water in the liquid is released, thereby reducing the water in the system and increasing the draining and cleaning effect. can.

The solvent from which water has been removed in this way is transported to the storage tank 8, and then returned to the draining tank 10 via the pump 1, the filter 2, and the fluorine O (oil porous sheet 3) from the pipe line 14, where it is again subjected to draining and cleaning. At the same time, a part of the solvent is transferred to the evaporation tank 11.
and is heated and evaporated here. The evaporated solvent vapor is condensed and liquefied in the cooler 15 and is conveyed to the water separation tank 9 through a pipe 16. The reason why this condensed solvent is returned to the water separation tank 9 is that the steam is in contact with the outside air in the upper layer, and the water vapor in the tank mixes here, condensing and the solvent contains water. Note that 17 and 18 in the figure are heaters, and the heater 17 is preferably used normally from the viewpoint of draining and cleaning effects, but is not necessarily necessary.
Reference numerals 9 and 20 indicate flow control valves that control the flow rates of the solvent to the draining tank and the evaporation tank, respectively.

FIG. 3 shows a case in which the solvent is supplied to the evaporation tank directly from the storage tank through the conduit 21 without passing through the filter 2 or the fluororesin porous sheet 3 in the apparatus shown in FIG. An inlet 22 for introducing the solvent into the pipe line 21 is opened to the liquid level of the storage tank. In other words, the inlet 22 controls the liquid level of the storage tank. In the apparatus shown in FIG. 3, a draining tank 10, a storage tank 9, a drainage gf
13. The filter 2 and the porous sheet 3 made of fluorine resin are connected in a closed circuit, and the water in the entire circuit is continuously removed by the tank 9 and the porous sheet 3 while the water is being cooled. The water content of the solvent in the storage tank is relatively low as it is also a part of the water. Therefore, there is no problem in introducing some of the solvent into the evaporation tank, and fjS
Compared to the case where a part of the route 14 is divided and introduced into the water separation tank 9 and the evaporation tank 11 as shown in Fig. 2, the device shown in Fig. 3 is more practical in that the liquid volume can be easily controlled. I can say that.

By using the apparatus shown in Figures f51 to 3, it is possible to continuously and effectively separate water from a water-containing organic solvent, and its industrial effects are exceptional.

(Example) A detailed explanation will be given below using examples.

Example 1 Using the apparatus shown in Fig. 1, toluene containing 600 ppm of water was cooled to 0°C, and then the mist of water was separated and the toluene containing water was passed through a porous sheet made of polytetrafluoroethylene. ) [Jg-sa], 01, porosity 75VO1%, maximum pore diameter 20μm, Daikin Industries (
When the toluene was passed through Polyflon Paper PA-101 (manufactured by Co., Ltd.), the toluene after passing contained only 245 pp+a of water. When this toluene was returned to a temperature of 7 m, the water in the toluene was sufficiently below its equilibrium solubility and could be effectively reused.

Example 2 Using the apparatus shown in Figure 3, 0.270% water was
An azeotrope mixture of 4% ethanol and 96% Freon 113 was cooled to 0°C, and then the azeotrope mixture containing water in the form of a mist was separated into a porous sheet made of polytetrafluoroethylene [thickness: 0.551, porosity 75vo
1%, maximum pore diameter 45 μm, manufactured by Daikin Industries, Ltd., Polyflon paper PA-5L) was passed through.
The azeotrope after passage contained only 0.192% water. When this azeotrope was returned to room temperature, the water in the azeotrope was well below its equilibrium solubility and could be effectively reused.

[Brief explanation of drawings]

1 to 3 are schematic diagrams of an apparatus to which the water separation method of the present invention is applied. 1 is a pump, 2 is a filter, and 3 is a 7-wire fj (a porous sheet made of fat.

Claims (1)

[Claims] (1) A method for separating water in an organic solvent, which comprises cooling an organic solvent containing water and then passing it through a porous sheet made of fluororesin.