JPH034902A - Method and device 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 the captioned 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. And 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, while a water separator 15 is provided to separate water from the condensate which is separated into an upper and lower layer. As the result, dissolved water in the solvents can effectively be removed and at the same time a compact device can be provided at low cost.

Description

[Detailed description of the invention] [Industrial application field] This invention uses halogenated organic solvents, namely l.

1.1-)! This invention relates to a device for removing dissolved water dissolved in chlorine-based organic solvents such as J dichlorothane, or fluorine-based organic solvents such as fluorocarbons.

[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. 137154/1986 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. We proposed a method for removing dissolved water in halogenated organic solvents.

[Problem to be solved by the invention]

This invention is directed to the method for removing dissolved water described above, which can exhibit high dehydration performance, and is compact and compact.
An object of the present invention is to propose an apparatus for removing dissolved water in a halogenated organic solvent, which can reduce costs.

[Means to solve the problem]

This device for removing dissolved water in halogenated organic solvents is a device that removes dissolved water in halogenated organic solvents 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 a condenser is provided between the outer cylinder of the apparatus and each shelf. The condenser has gas circulation gaps that are continuous in the vertical direction, and the condenser has multiple rows of cooling pipes surrounding the shelves and a collection groove below them that collects the condensate that drips. It is characterized by being equipped with a water separator that separates a water layer and a solvent layer, which are divided into two upper and lower layers. Another 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 the device has one or more trays and a condensate in an outer cylinder. Each shelf has a heating means for evaporating the solvent, a flow path for allowing the solvent sent from above to flow downward, and a space between the outer cylinder of the device and each shelf is provided. The condenser has gas circulation gaps that are continuous in the vertical direction, and the condenser has multiple rows of cooling pipes surrounding the shelves and a collection groove below them that collects the condensate that drips. Comes with a water separator that separates the water layer and solvent layer, which are divided into upper and lower layers, and the water outlet of the water separator is connected to the outside of the device, and the solvent outlet that separated the water layer is connected to the liquid storage tank at the bottom of the device. It is characterized by:

〔Example〕

The present invention will be explained below with reference to illustrated embodiments.

1st. Figure 2 shows the removal device according to the present invention.

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

The shelf 2 has an open solvent space 8 in which the solvent 7 stays on the upper surface.
, a closed steam space 9 on the lower surface (an electric heater may be used as the heating means), and a cylindrical liquid flow path 10 through which the solvent flows 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 is the solvent/agent 7.
The outflow port opens into the solvent 7 on 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 1 surrounds 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 sent in from the top and end, and is discharged from the bottom (the flow direction of the cooling water is from the bottom). (may be reversed 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.

The collected condensate is separated into an upper water layer 13 and a lower solvent layer 14 due to the difference in specific gravity within the liquid collecting groove 4. This condenser 5 has a water separator 15 and a solvent outlet pipe 16 attached to two diagonal corners of the liquid collecting groove 4. The water separator 15 has a separating plate 17 of a predetermined height arranged between it and the liquid collecting groove 4, from which the upper water layer of the condensate overflows, and a water reservoir 18 where the overflowing water is retained, and the outside of the outer cylinder 1. A drain pipe 19 that opens to the drain pipe 19 and a roofed shielding plate 20 that straddles and covers the upper surface of the liquid collecting groove 4 are provided.

The solvent extraction pipe 16 attached to the opposite corner is located in the enlarged part of the liquid collecting groove 4 closer to the center than below the cooling pipe 3, and a shielding pipe 21 is arranged on the outside of the upper end, and its height is Separation plate 17
The lower end penetrates the bottom of the liquid collection groove 4 and extends downward, so that the solvent overflowing into the take-out pipe 16 is sent to the liquid storage tank 6 at the bottom of the device. There is a configuration to send and one without.

The liquid storage tank 6 is provided with a liquid feeding pipe 22 and a pump 23 for feeding the internal solvent onto the uppermost shelf 2, and a supply pipe 28 for introducing the solvent from the outside. In the drawings, 24 is a cooling water pipe, 25 is a steam pipe, and 26 is a steam trap. In addition, although the upper part of the outer cylinder 1 is open,
A lid is attached as appropriate to prevent dust from entering.

To remove dissolved water using this device, the solvent 7 containing dissolved water in the liquid storage tank 6 is continuously sent to the uppermost shelf 2 at a predetermined flow rate via the liquid sending pipe 22. At the same time, steam and cooling water are sent from the steam pipe 25 and the cooling water pipe 24 to 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 separated into an upper water layer 13 and a lower solvent layer 14 due to the difference in specific gravity between water and solvent, so the water layer 13 is separated by a water separator 15 and the discharge pipe 19 is taken out of the device via the The solvent containing the dissolved water from which the aqueous layer has been separated falls into the liquid storage tank 6 via the solvent extraction pipe 16 and is 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 is also efficiently condensed and collected in the liquid collecting groove 4.

Further, a cooling pipe 3 is also installed in the liquid collection groove 4 to suppress the temperature rise of the condensed liquid.

In this embodiment, a roofed shielding plate 20 is placed on the upper surface of the water separator 15 so as to straddle the liquid collection groove 4 , and the lower edge of the periphery of the shielding plate 20 extends into the water layer 13 .

This shielding plate can prevent fine droplets of the solvent falling from above and floating on the surface of the water layer 13 from entering the water separator 15 together with the water layer.

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 contains this amount of dissolved water 1, 1.1-)! When J chloroethane is simply distilled, water with a high boiling point is concentrated in the initial distillate, resulting in 15% of the liquid volume.
It has been confirmed that by removing a certain amount of the initial distillate, the water content in the solvent residue in the evaporator, that is, the distillation mother liquor, can be reduced to almost zero.

That is, in order to remove dissolved water from water-saturated 1,1,1-trichloroethane in this example, an initial distillate amount equivalent to 15% of the fed solvent was added 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 a certain amount of stabilizer added, and the type, amount, and temperature of the stabilizer have many effects;
Contains dissolved water in the range of ~1000 ppm.

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% for 1,1,1-trichloroethane, trichlorethylene, perchlorethylene, methylene chloride, and Freon 113 for 1,1,1-trichloroethane, 5-20 5-10 40-60 5-30. A solvent containing almost no alcohol can be obtained as a distillation mother liquor.

As shown in FIG. 3, this dissolved water removal device may not include a liquid storage tank at the bottom of the device, and the tip of the solvent extraction pipe 16 may be opened outside the device. In this case, the solvent containing dissolved water in the liquid collecting groove 4 from which the aqueous phase has been separated passes through the take-out pipe 16 and is stored in a storage tank outside the apparatus (not shown), and is sent from this storage tank to an upper shelf inside the apparatus. and then returned to the dehydration process.

In addition to the above-mentioned embodiments, this device also includes, for example, a fourth
A phase separator 27 in which a water separator 13 and a solvent extraction pipe 16 are combined as shown in the figure can be attached to the liquid collecting groove 4.

[For production]

This dissolved water removal device has the above-mentioned configuration, and is equipped with one or more shelves in the outer cylinder of the device, a condenser consisting of multiple rows of cooling pipes and liquid collecting grooves surrounding the shelves, and a condenser on each shelf. The solvent gas evaporated on the stage is condensed in a short time, and compared to the case where a condenser is provided outside the outer cylinder, gas-liquid mixing and re-condensation on the stage surface are less likely to occur, and dehydration performance can be significantly improved. In addition, because the shelves, condenser, and water separator are housed in the outer cylinder of one device, the outer cylinder cost is low, the number of connecting pipes is reduced, and it can be made compact, resulting in lower costs. It can be achieved.

In addition, the removal device in item (2) houses the trays, condenser, water separator, and liquid storage tank section for storing the water-containing solvent from which the aqueous layer has been separated from the condensed liquid in one common outer cylinder. So,
- It is possible to reduce the cost and compactness of the layer height.

〔Effect of the invention〕

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

[Brief explanation of the drawing]

Figure 1.2 is an AA cross-sectional view and a plan view of the dissolved water removal device of the example, Figure 3 is a cross-sectional view of the device of another example, and Figure 4 is a combination of a water separator and a solvent extraction pipe. FIG. 2 is a cross-sectional view of a phase separator. 1...Outer cylinder, 2...Shelf, 3...Cooling pipe, 4...
・Liquid collection groove,...5...Condenser, 6...Liquid storage tank, 7
... Solvent, 8 ... Solvent space, 9 ... Steam space, 10 ... Liquid flow path, 11 ... Partition plate, 12 ... Gas circulation gap, 13 ... Water layer, 14...solvent layer, 1
5...Water separator, 16...Solvent extraction pipe, 17...
Separation plate, 18... Water reservoir section, 19... Drain pipe, 20.
・・Shielding plate, 21 ・・Shielding tube, 22 ・・Liquid pipe, 2
3... Pump, 24... Cooling water pipe, 25... Steam pipe, 26... Steam trap, 27... Phase separator, 28... Supply pipe.

Claims (2)

[Claims] (1) This is a device that removes dissolved water in a halogenated organic solvent as a condensate of the initial distillate.
Equipped with a stage or multiple stages of shelves and a condenser, each stage has a heating means for evaporating the solvent, a flow path for causing the solvent sent from above to flow downward, and the outer cylinder of the device and each stage are connected to each other. The condenser has a gas circulation gap that continues in the vertical direction of the shelf between the two, and the condenser has multiple rows of cooling pipes surrounding the shelf and a liquid collecting groove below the cooling pipe to collect dripping condensate. An apparatus for removing dissolved water in a halogenated organic solvent, characterized in that it is equipped with a water separator that separates a collected condensate into two upper and lower layers: a water layer and a solvent layer. (2) A device that removes dissolved water in a halogenated organic solvent as a condensate of the initial distillate.
Equipped with a stage or multiple stages of shelves, a condenser and a liquid storage tank,
Each shelf has a heating means to evaporate the solvent, a flow path that allows the solvent sent from above to flow downward, and gas flow continues between the device outer cylinder and each shelf in the vertical direction of the shelf. The condenser has a gap, and the condenser has multiple rows of cooling pipes surrounding the shelves and a liquid collection groove below the cooling pipes to collect dripping condensate,
A water separator is attached to separate the collected condensate into two upper and lower water layers and a solvent layer, and the water outlet of the water separator is located outside the device.
1. An apparatus for removing dissolved water in a halogenated organic solvent, characterized in that a solvent outlet from which a water layer has been separated is connected to a liquid storage tank at the bottom of the apparatus.