JP4921689B2 - Method for removing residual organic solvent in solid substance - Google Patents

Description

[0001]
[Technical field to which the invention belongs]
The present invention relates to a method for removing a non-hydrophilic solvent remaining in a solid substance such as a filter cake.
[0002]
[Prior art]
Examples of the method for removing and washing the organic solvent remaining in the filter cake after the filtration operation include a method of removing the residual organic solvent molecules from the crystal structure of the bulk material, and replacing the residual organic solvent molecules with water vapor molecules. There are known methods for removing residual aeration solvent molecules that include vacuum hydration of bulk material. (See Patent Document 1)
[0003]
It is also known to use a filter having a rotary filter and wash the filter cake with hot water or steam. (See Patent Document 2)
[0004]
[Patent Document 1]
JP-A-11-147844 [Patent Document 2]
Japanese Patent No. 2895084 [0005]
[Problems to be solved by the invention]
However, although the above-described method is effective for removing the hydrophilic solvent, it is not necessarily effective for removing the non-hydrophilic solvent. In addition, there are disadvantages such as that it takes time to remove the solvent or that the solvent cannot be completely removed. In the suction method under reduced pressure, the filter cloth repeatedly moves up and down due to filtration, cake washing, drying, etc. over a long period of time, and the fixing part of the filter cloth fixed to the filter plate is gradually damaged and filtered. The cake leaks to the filtrate side.
In addition, when vacuum decompression operation is performed to remove non-hydrophilic solvent by azeotropy by adding water, the filter cake becomes dusty and the vacuum system piping is blocked, or when the filter cake is discharged, dusting is severe. Or the filter cloth was raised and the filter cake leaked.
In addition, there is a problem in that the filter is a rotary type and the apparatus becomes complicated, and sufficient cleaning cannot be performed for a long time with high pressure.
[0006]
An object of the present invention is to provide a method for completely removing a non-hydrophilic solvent remaining in a solid substance such as a filter cake by using a relatively simple solid-liquid separator.
[0007]
[Means for Solving the Problems]
As a result of intensive studies to solve the above problems, the present inventors have been able to efficiently remove the non-hydrophilic organic solvent in a short time by washing the solid substance with water vapor under pressure. As a result, the present invention has been completed.
[0008]
That is, the present invention
(1) A method for removing a residual organic solvent in a solid substance, wherein the solid substance containing a non-hydrophilic organic solvent is washed with water vapor under pressure,
(2) The method for removing a residual organic solvent in a solid material according to (1), wherein the solid material is a filter cake on a filter plate filtered by a filter,
(3) The method for removing a residual organic solvent in a solid substance according to (1) or (2), wherein the temperature of the water vapor is in the range of 70 to 110 ° C.
(4) The method for removing a residual organic solvent in a solid substance according to any one of (1) to (3), wherein the non-hydrophilic solvent is a solvent azeotropic with water,
(5) The present invention relates to the method for removing a residual organic solvent in a solid substance according to any one of (1) to (4), characterized by washing with an inert gas during or after washing with water vapor.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The method for removing a residual organic solvent in a solid substance of the present invention is characterized in that a solid substance containing a non-hydrophilic organic solvent is washed with water vapor under pressure. The solid substance used in the method of the present invention is not particularly limited, but is preferably a filter cake on a filter plate that has been filtered by a filter.
The filter to be used is not particularly limited, and a filter according to a known filter can be used, and will be specifically described with reference to FIG.
The filter has a Nutsche type structure, and the filter plate (or filter plate) (1) has a horizontal circular hole and is provided with a bell-like mirror (2) covering the top, A filter medium (3) such as a filter cloth is installed in the filter panel (1).
A supply pipe (4) for the suspension to be filtered is provided on the inner upper part of the mirror part (2) so that the suspension can be supplied to the filter plate (1). Similarly, water vapor pipes (5) are installed independently or in combination. Furthermore, an inert gas introduction pipe (6) for drying the cake is installed on the inner upper part of the mirror part (2).
[0010]
A collecting pipe (11) is piped to the lower part of the filter plate (1) and connected to the transfer pipe (12), and the filtrate (mother liquid) that has passed through the filter plate and the used water or drain are treated afterwards. In order to do this, it is transported from the filter to the target location.
Furthermore, the filter used in the present invention can be used by adding various well-known and commonly used functions. Specifically, when filtering with the pressure inside the filter under pressure, the filter cloth adheres to the filter board and the filtration speed deteriorates, so the filter cloth is floated, so a support mesh (metal mesh) ( 7) is inserted.
[0011]
In addition, the filter is provided with a stirring blade (8) and a discharge rod (9) for discharging the filter cake after completion of the filtering operation.
The stirring blade (8) can be moved up and down in the filter and has a structure that can be lifted and retracted so as not to come into contact with the filtrate or the filter cake during the filtration operation. At the upper part of the filter mirror part, a filter aid charging rod (10) for charging the filter aid is attached.
[0012]
Next, the implementation method of this invention is demonstrated.
A liquid in which a filter aid such as activated clay or cellulose is suspended is directly supplied from the filter aid input (10) onto the filter medium (3) in the filter and pre-coated with the filter medium (3) or filtered. A filter aid is added to the suspension in advance and mixed, and the mixture is supplied from the suspension supply pipe (4) onto the filter medium (3) in the filter to pre-coat the filter medium (3). Thereafter, the suspension to be filtered is supplied from the suspension supply pipe (4), and the stirring blade (8) is appropriately moved up and down to adjust the thickness of the cake on the filter medium (3). Usually, the thickness of the filter cake is 20 to 30 mm, but the thickness of the filter cake can be appropriately determined by selecting the physical properties of the filter cake and the subsequent treatment conditions with water vapor.
[0013]
The filtrate (mother liquor) passes through the filter medium (3) and the filter plate (1), is collected by the collecting pipe (11), and is carried to the target place through the transfer pipe (12).
Steam is supplied from the pipe (5) to the entire surface of the filter cake. In the case of water vapor, water vapor and drain are dispersed on the filter cake. The temperature of the water vapor at this time is 70 to 110 ° C., and the pressure in the filter is maintained at 60 to 180 kPa (gauge pressure), preferably 60 to 150 kPa (gauge pressure). When the pressure is 60 kPa or less, pressure filtration does not proceed at a sufficient speed, and even if the pressure is increased by 180 kPa or more, no advantageous effect can be expected. The water vapor supplied into the filter passes through the filter cake, moves the non-hydrophilic solvent in the cake from the cake, flows along with water such as drainage to the collecting pipe (11), and passes through the transfer pipe (12). Carried to the destination location. Since the filtrate (mother liquor) contains a non-hydrophilic organic solvent, the filtrate is separated into an aqueous layer and an organic layer, and the organic layer is recovered by dehydration after washing with water.
[0014]
The non-hydrophilic organic solvent contained in the solid substance subjected to the method of the present invention is not particularly limited as long as it is an organic solvent that is not mixed with water, but in particular, azeotropic with water such as benzene, toluene, xylene and the like. An organic solvent is preferred.
Water and steam are supplied for 2 to 5 hours. When the supply of water or water vapor is completed, an inert gas is passed through the filter, the water and drain remaining in the cake are discharged, and the filter cake on the filter medium is dried. As the inert gas, a gas that does not react with the components of the filter cake is selected, and nitrogen gas is usually used for economic reasons. After drying, the filter is slowly lowered while rotating the stirring blade to scrape off the filter cake and scrape it out of the discharge pan.
[0015]
EXAMPLES Hereinafter, although this invention is demonstrated further in detail using an Example, this invention is not limited to an Example.
[0016]
【Example】
Example 1
Same as shown in FIG. 1 having a circular filter with a diameter of 2 m, pre-coated with 1700 kg of toluene solution containing the catalyst used in the reaction, crystals of by-produced salt, etc., and the reaction product with a filter aid. The mixture was filtered with a simple filter and further washed with 300 kg of toluene. The filtrate was directly used for the next step.
To the filter cake, steam at 100 ° C. was further supplied to the filter plate for 3 hours. The pressure in the filter was 150 KPa. By this operation, toluene contained in the filter cake was further recovered. Thereafter, nitrogen gas was passed through the filter cake for 30 minutes to dry, slowly lowered while rotating the stirring blade, scraped off the filter cake, and the crystals were scraped from the discharge.
Toluene contained in the obtained crystals of X was below the reference value that can be treated as waste.
[0017]
【Effect of the invention】
As described above, by using the method of the present invention, it is possible to easily remove a non-hydrophilic organic solvent from a solid substance to a concentration below the detection limit or below that does not cause a practical problem. When disposing of unnecessary solid substances, it can be efficiently recovered and reused without discharging organic solvents into the environment, and it can be said that the industrial utility value is high.
[Brief description of the drawings]
FIG. 1 shows a conceptual diagram of a filter used in the method of the present invention.
[Explanation of symbols]
1. Filter board 2. Mirror part 3. Filter medium 4. 4. Suspension supply pipe Steam piping 6. 6. Inert gas introduction pipe Support mesh8. 8. Stirring blade Ejection 10. 10. Add filter aid Collective piping 12. Transfer pipe

Claims (3)

The toluene solution containing the reaction product solid shape material Ru Ah in the filter cake on the plate filtration obtained by filtration by filter, water vapor was washed with a pressure of 60～180KPa (gauge pressure), solid A method for removing a residual organic solvent in a solid substance, wherein toluene contained in the shaped substance is recovered as a filtrate through a filter board . The method for removing a residual organic solvent in a solid substance according to claim 1, wherein the temperature of the water vapor is in the range of 70 to 110 ° C. The method for removing a residual organic solvent in a solid substance according to claim 1 or 2, wherein washing with an inert gas is performed during or after washing with water vapor.

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