JPH034901A - Method and apparatus for removing dissolved water in halogen organic solvent - Google Patents

Abstract

PURPOSE:To effectively remove dissolved water in solvents by feeding solvents containing dissolved water into a distillation device equipped with plates therein, thereby cooling and condensing the evaporated gases thereof in an outer cylinder of said device to separate the condensate of initial fraction from the mother liquid of distillation. CONSTITUTION:One or a plurality of plates 2 and a condenser 5 are provided in an outer cylinder 1 of a distillation device, wherein each of the plates 2 is equipped with a heating means 9 to evaporate solvents and a fluid passage 10 to allow the solvents fed from the upper side to flow downward, while a continuous gas flow space 12 extending vertically between the cylinder 1 and the plates 2 is provided and the condenser 5 encircling the plates 2 comprises a plurality of rows of cooling tube 3 and a liquid collecting trough 4 disposed at the lower end of the tube 3 to collect the condensate falling in drops. Solvents containing dissolved water are continuously fed to the distillation device provided with the plates 2, where a part thereof is evaporated so that the evaporated gas is cooled and condensed in the cylinder 1 to separate the condensate of initial fraction from the distillation mother liquid. As a result, dissolved water in the solvents can effectively be removed.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to halogenated organic solvents, namely 1°1.1-
)! The present invention relates to a method and apparatus for removing dissolved water dissolved in a chlorinated organic solvent such as dichlorothane or a fluorinated organic solvent such as fluorocarbon.

[Conventional technology]

Conventionally, free water in the solvent is removed by phase separation,
Dissolved water is removed using an adsorbent such as zeolite, silica, or ion exchange resin. However, this method has problems such as the adsorption power of the adsorbent gradually decreasing, requiring time and effort to regenerate and replace the adsorbent, and fine powder of the adsorbent being easily mixed into the solvent.

As a method for solving the above-mentioned problems, the inventors of the present application previously disclosed in Japanese Patent Application No. 137154/1982 that a solvent containing dissolved water is subjected to simple distillation, and the dissolved water is removed from the distillation mother liquor together with its initial distillate. A method for removing dissolved water in halogenated organic solvents was proposed.

[Problem to be solved by the invention]

This invention further improves the method for removing dissolved water described above, and provides a method for removing dissolved water in halogenated organic solvents that achieves even higher dehydration performance, and a dissolved water removal device that is inexpensive, compact, and has excellent dehydration performance. There are suggestions.

[Means to solve the problem]

The method for removing dissolved water in a halogenated organic solvent of the present invention is a method in which the halogenated organic solvent containing dissolved water is simply distilled, and the dissolved water is separated and removed from the distillation mother liquor together with the condensate of the initial distillate. The solvent containing dissolved water is continuously fed into a distillation device equipped with one or more trays inside.
It is characterized by evaporating a part of it, cooling and condensing the evaporated gas within the outer cylinder of the device, and separating the condensate of the initial distillate from the evaporated mother liquor.

Another dissolved water removal device according to the invention is a device that removes dissolved water in a halogenated organic solvent as a condensate of the initial distillate, and has one or more shelves in the outer cylinder of the device. Each shelf has a heating means for evaporating the solvent, a flow path for allowing the solvent sent from above to flow downward, and between the outer cylinder and each shelf, the upper and lower parts of the shelf are provided. The condenser has a gas flow gap continuous in the direction, and the condenser is characterized by having a plurality of rows of cooling pipes surrounding the shelf and a liquid collection groove below the cooling pipes to collect dripping condensate.

〔Example〕

The method for removing dissolved water and the apparatus for removing dissolved water used in this example will be described in detail below.

This dissolved water removal device consists of an outer cylinder 1 with a square (or circular cross-section) open top surface, three shelves 2 inside the cylinder, a condenser 5 consisting of a cooling pipe 3 and a liquid collection groove 4, and a bottom part. It consists of a liquid storage section 6.

The shelf 2 has an open dissolution space 8 in which the solvent 7 stays on the upper surface.
, a steam space 9 closed at the bottom (an electric heater may be used as the heating means). It has a cylindrical flow path 1o that allows the solvent to flow downward.

In the solvent space 8, a partition plate 11 is disposed between an inlet and an outlet of a flow path 10, and a bent flow path is formed. Note that the inlet of the flow path 10 opens to the liquid level of the solvent 7, and the outlet opens into the solvent 7 of the lower shelf 2. Further, the outlet of the liquid flow path 10 of the lowermost shelf 2 is open to the outside of the outer cylinder 1.

The dimensions of this shelf 2 are smaller than the cross section of the outer cylinder 1, and the outer cylinder l surrounding the shelf 2 (or may be partially closed)
A vertically continuous evaporative solvent gas circulation gap 1 between
2 is formed. The cooling pipe 3 of the condenser 5 extends from above to below the top and bottom shelves 2, 2,
Surrounding the shelf 2, piping is arranged in multiple rows in a spiral shape within the circulation gap 12, and the cooling water is fed in from the upper end and discharged from the lower end (the flow direction of the cooling water is reversed from the bottom to the top). ).

The liquid collection groove 4 has a rectangular cross section, and is arranged in a square ring shape along the inner surface of the outer cylinder 1 below the cooling pipe 3 to collect condensed liquid. In this liquid collection groove 4, there is a cooling pipe 3 at the lowest stage.
A condensate discharge pipe 13 extending from the liquid collection groove 4 to the outside of the outer cylinder 1 is attached.

The bottom of the outer cylinder 1 is a liquid storage part 6, and the uppermost shelf 2
A liquid feed pipe 14 and a pump 15 for feeding the solvent upward, and a supply pipe 19 for introducing the solvent from the outside are provided.

In addition, in the drawing, 16 is a cooling water pipe, 17 is a steam pipe, and 18 is a cooling water pipe.
is a steam trap. Further, although the upper part of the outer cylinder 1 is open, a lid is appropriately attached to prevent dust from entering.

This dissolved water removal device has the above configuration.

The method for removing dissolved water using this device will be described in detail below.

The solvent 7 containing dissolved water in the liquid storage section 6 is continuously fed to the uppermost shelf 2 at a predetermined flow rate via the liquid feed pipe 14, and at the same time steam is transferred from the steam pipe 17 and the cooling water pipe 16. and cooling water are sent into the steam space 9 and the cooling pipe 3, respectively.

The solvent 7 sent to the shelf 2 flows through the bent solvent space 8, falls from the flow path 10, and in the process of flowing through the three shelves 2, a part of it evaporates, and some of the initial distillate is Almost all dissolved water is removed. The remaining evaporated mother liquor becomes a solvent from which dissolved water has been removed, and is continuously taken out of the outer cylinder 1 through the lowermost flow path 10. The water-containing solvent gas evaporated on each shelf has a high density and passes through the gas circulation gap around the shelf, but is cooled by the plurality of rows of cooling pipes surrounding the shelf, becomes a condensed liquid, and is collected in the liquid collecting groove 4. The condensed liquid in the liquid collection groove 4 is taken out to the outside of the outer cylinder 1 through the discharge pipe 13 and separated into an upper water layer and a lower solvent layer by phase separation, and the solvent layer containing dissolved water is transferred to the liquid seed storage section 6. and then returned to the dehydration process.

In this device, at least the lowest cooling pipe 3 is arranged below the solvent liquid level of the lowest shelf 2,
The liquid collecting groove 4 is located further below. Therefore, the solvent gas evaporated from the lowest stage can also be efficiently condensed and collected in the liquid collecting groove 4.

In this invention, when a halogen-based organic solvent in which a small amount of water is dissolved, when distilled, the water percentage in the gas phase becomes significantly higher than the water percentage in the solvent liquid phase, and almost all of the water is present in the condensate at the initial stage of distillation. This is based on the new knowledge that dissolved water distills out. For example, 1.1.1-trichloroethane (pure product containing no stabilizers) with a boiling point of 74°C has a boiling point of about 250°C at 20°C.
ppm of water, but when 1,1.1-)lichloroethane containing this amount of dissolved water is simply distilled, water with a high boiling point is concentrated in the initial distillate, and 15% of the liquid volume is It is certain that by removing a certain amount of the initial distillate, the residual solvent in the evaporator, that is, the water content in the distillation mother liquor, can be reduced to almost zero.

That is, in this example, in order to remove dissolved water from water-saturated 1,1.1=trichloroethane, an initial distillate equivalent to 15% of the fed solvent was removed in one or more trays. The device should be operated under conditions that allow separation.

The halogenated organic solvents to be treated in this invention are 1,
1.1-) Lichloroethane, trichloroethylene, perchloroethylene, methylene chloride, Freon 113, etc. The amount of saturated dissolved water varies depending on the chemical structure of the solvent, but commercially available solvents have some stabilizer added, and the type, amount, and temperature of the stabilizer have many effects.
Contains dissolved water in the range of ~11,000 pp.

The rate at which the initial distillate is separated varies depending on the type of solvent, the type and amount of stabilizer, and the moisture content of the stock solution. The ratio increases as the moisture content of the stock solution increases, as the amount of saturated dissolved water increases, and as the amount of water-soluble stabilizer increases. - For boat fishing, the ratio to be removed as initial distillate is 5 to 5 to the amount of supplied liquid.
60%, but 1.1.1) For Lichloroethane 5-40% For Trichlorethylene 5-20 For Perchlorethylene 5-10% For Methylene Chloride 40-6
By setting the ratio to 5 to 30 for 0 Freon 113, a solvent containing almost no water can be obtained as a distillation mother liquor.

[For production]

This invention consists of the above configuration. In this method for removing dissolved water, a water-containing solvent is continuously supplied, evaporated in one or more trays, water is removed together with the initial distillate, and a dehydrated solvent can be obtained continuously. Since the solvent gas containing evaporated water is cooled and condensed in the same outer cylinder as the shelf, the residence time of the gas is shorter than when it condenses outside the outer cylinder. Condensation is difficult to occur and dehydration performance is significantly improved. Therefore, by combining evaporation using one or more trays and condensation within the same outer cylinder, dissolved water can be removed extremely efficiently.

This dissolved water removal device is equipped with a condenser consisting of one or more shelves in the outer cylinder of the device, and multiple rows of cooling pipes and liquid collecting grooves surrounding the shelves, and the solvent gas evaporated on each shelf is is condensed in a short time, and the dewatering performance can be significantly improved compared to the case where a condenser is provided outside the outer cylinder. Furthermore, there is no need for piping to connect the evaporator and condenser, and there is no need to consider pressure loss due to the connecting piping, and since the outer cylinder is shared, compactness and cost reduction can be achieved.

〔Effect of the invention〕

The present invention is as described above, and the method and apparatus for removing dissolved water can efficiently remove dissolved water in a solvent. Furthermore, the device can be made more compact and cost-effective.

[Brief explanation of drawings]

FIG. 1.2 is a sectional view and a plan view, respectively, of an apparatus for removing dissolved water in a halogenated organic solvent according to an example. 1...Outer cylinder, 2...Shelf, 3...Cooling pipe, 4...
・Liquid collection groove, 5... Condenser, 6... Liquid storage side part, 7...
・Solvent, 8... Solvent space, 9... Steam space, 1
0... Liquid flow path, 11... Partition plate, 12... Gas circulation gap, 13... Discharge pipe, 14... Liquid feeding pipe, 15
Pump, 16... Cooling water pipe, 17... Steam pipe, 18... Steam trap, 19... Supply pipe. 1 applicant: Asahi Kasei Industries, Ltd.

Claims (3)

[Claims] (1) This is a method in which the halogenated organic solvent containing dissolved water is simply distilled and the dissolved water is separated from the distillation mother liquor together with the condensate of the initial distillate and removed. Alternatively, it is continuously fed into a distillation device equipped with multiple trays, a part of it is evaporated, the evaporated gas is cooled and condensed in the outer cylinder of the device, and the condensate of the initial distillate is extracted from the distillation mother liquor. A method for removing dissolved water in a halogenated organic solvent, the method comprising separating water. (2) A device that removes dissolved water in a halogenated organic solvent as a condensate of the initial distillate, and is equipped with one or more trays and a condenser inside the outer cylinder of the device, and each tray is equipped with one or more trays and a condenser. It has a heating means for evaporating the solvent, a flow path for causing the solvent sent from above to flow downward, and a gas circulation gap that is continuous in the vertical direction of the shelf between the outer cylinder and each shelf, An apparatus for removing dissolved water in a halogenated organic solvent, characterized in that the condenser has a plurality of rows of cooling pipes surrounding the trays and a collection groove located below the cooling pipes to collect dripping condensate. (3) The cooling pipe in the lowermost stage is equal to or lower than the solvent liquid level in the lowest shelf. Dissolved water removal equipment.