JPH04193302A - Solvent removal method - Google Patents

Abstract

PURPOSE:To surely remove the solvent or the low boiling point component in the product solution and to attain the improvement of the product recovery rate by heat-evaporating the solvent with a heat evaporator, subsequently discharging into a tank, etc., at a lower pressure than a pressure in the heating evaporator and removing the solvent. CONSTITUTION:The hexane solution of a high molecular compound is steam- heated in the centrifugal film evaporator 1 under an atmospheric pressure and a residual rate of hexane in the high molecular compound is reduced and it is discharged into a evacuated tank 11 with an intermediate pump. As a result, the solvent or the low boiling point component in the product solution of the high boiling point compound or the high molecular compound, etc., is surely removed and the major part of the solvent or low boiling point component can be condensed in a high pressure state, so the recovery rate is high and the total cost can become advantageous.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a desolvation method for removing as much of the solvent or low-boiling point components as possible from a solution of a high-boiling point compound or polymer compound and a solvent or low-boiling point component. It is related to.

[Conventional technology]

Conventional ** uses only one stage of heating evaporator to heat and evaporate under pressure that can remove the solvent or low boiling point components, or connects two or more stages of heating evaporators in series and lowers the pressure in the latter stage than in the first stage. , to remove solvents or low-boiling components.This will be explained below with reference to the drawings.

Figure 2 shows an example in which a centrifugal thin film evaporator is used as a heating evaporator.The stock solution is converted to IIM by centrifugal force in a vacuum and heated with steam from the outside in an attempt to remove as much of the solvent in the product as possible. It is something. The product is extracted by the product pump 4, while the evaporated solvent is removed from the condenser 2 due to the vacuum.
It is often cooled and condensed using a refrigerant that is colder than water.

In FIG. 3, the solvent is evaporated in the heating evaporator 6 operated at atmospheric pressure in the first stage, and can be condensed with water in the k-group unit 7. 2
In the case of JiN, the solvent is removed using a centrifugal thin film evaporator l in a vacuum similar to that shown in Figure 112.

Note that related devices of this type include, for example,
Tokusushi Sho 63-132850 is listed.

[Problem to be solved by the invention]

Does the above conventional technology have a lower product recovery rate? If you try to remove the solvent or low-boiling point components with only one stage of heating Ji generator without considering the equipment price, you will need a low-temperature refrigerant because the pressure is low to recover the evaporated solvent or low-boiling point components. Therefore, if the pressure is a vacuum, some of it will be released into the atmosphere, and the recovery rate will be a. In addition, if two or more stages of heating evaporators are connected in series and the pressure is lowered in the stage after the pouring to remove the solvent or low boiling point components, the recovery rate is better than with one stage of heating evaporators, but the equipment cost is higher. There were problems such as high-pitched sound.

An object of the present invention is to provide an inexpensive solvent removal method that can reliably remove the solvent or low-boiling point component from a product solution and improve the product recovery rate.

[Means to solve the problem]

Considering the purpose of evaporating and recovering solvents or low-boiling components in product solutions such as high-boiling compounds and polymer compounds, it is advantageous to have a high pressure in the evaporator. On the other hand, for the purpose of removing the solvent or low boiling point components, it is advantageous that the pressure in the evaporator is low. In order to achieve both of these objectives, the pressure of the heating evaporator that evaporates and recovers most of the solvent or low-boiling point components is high, and by increasing the temperature of the product solvent, the solvent or low-boiling point components can be recovered by increasing the temperature of the product solvent. Evaporate as much as possible and release the hot product solution to the lower pressure tank of the heating 1A generator or cyclone to self-evaporate the small amount of solvent or low boiling point components remaining in the product solution without heating. Let me, solvent! or low boiling point components efficiently.

In addition, in the present invention, the M flowing down to the high-pressure heating evaporator
Using a 1ll belly evaporator or a centrifugal thin film evaporator can increase the temperature of the product solution to more efficiently evaporate the alkaline agent or low-boiling components.

In history, product #l! If you select a pressure that allows the solvent or low-boiling components in the solution to be removed to 1-1 or less with a heating evaporator, the pressure will be lowered by self-evaporation of the solvent or low-boiling components remaining in the product solution after being released into a low-pressure tank, etc. The temperature of the product solution is negligible, and therefore the residual rate of solvents or low-boiling components is also reduced.

[For production]

By raising the temperature of a high-boiling point compound or product solution containing high-boiling point compounds, the solvent or low-boiling point components in the product can be easily removed even under high pressure. However, if the remaining rate is not far from the specified value,
If the dish is discharged into a low-pressure tank or the like, the solvent or low-boiling point components can be removed using its own thermal energy. 20S
Since the remaining solvent or low-boiling point components are small, the product temperature hardly decreases even without external heating, and therefore a product with low residual carbon content in terms of IIi+ is obtained.

On the other hand, since most of the evaporated solvent or low boiling point components are in a high pressure state, they can be condensed with cooling water.

The amount on the lower pressure side is small, so vacuum it! You can also exhaust the air with all.

〔Example〕

Below is an example of the present invention. This will be explained using IvA. In the figure, when a hexane solution of a certain polymer compound was steam-heated in a centrifugal thin film generator at atmospheric pressure and heated to 150°C, the residual rate of hexane in the high-boiling point compound decreased to 0.211. . This is pumped to a pressure of 1 by the intermediate pump 10.
When the mixture was discharged into a vacuum tank U at 104 Pa, the residual rate of hexane in the polymer compound was 0.01- or less. The temperature of this wild product polymer compound is 149°C.
The product was removed from the product pump 4 after only a drop in temperature. In addition, a sufficient degree of vacuum was obtained using a water ejector for evacuation.

According to this embodiment, the condensation of hexane by the condenser 2 can be carried out under atmospheric pressure, so that the cooling water produced by the ordinary cooling tower is sufficient. Furthermore, since the decompression tank (2) has a simple structure, it is inexpensive in terms of cost.

〔Effect of the invention〕

According to the present invention, it is possible to reliably remove solvents or low-boiling point components in product solutions such as high-boiling point compounds and polymer compounds, and most of the solvents or low-boiling point components can be condensed under high pressure. , the recovery rate is high, no particularly low-temperature refrigerant is required, and the overall cost is advantageous.

[Brief explanation of the drawing]

JIIIC is a flow sheet diagram showing an example of the solvent removal method of the present invention, IS2 diagram, J83 diagram - is a flow sheet diagram showing an example of the solvent removal method according to the prior art. l...Centrifugal thin film evaporator, 2,7...Condenser, 3゜8...Solvent receiver, 4...Product pump, 5.9 ...solvent pump, 6...
... Heating evaporator, 10 ... Intermediate pump, 11
・・・・・・Reduction tank, confirmation ・・・・Water ejector
Agent Patent Attorney tJ-Katsuo Kawa-7-'o l
Figure t ----L%: Usushisho planning z ----; vLl#I each j-111 lacquer receiving each 4----! ! A-product pump 2 5-----Ikkaku Po〉lθ---One-inch inspection bomber-I/----Pressure button 7 12----IF-Eze 7 ter

Claims (1)

[Claims] 1. In a method for removing a solvent or a low-boiling point component from a product solution such as a high-boiling point compound or a polymer compound, after the solvent or low-boiling point component is heated and evaporated in a heating purifier, heating is performed. A desolvation method characterized by removing the solvent or low boiling point components by discharging the solvent into a tank or cyclone having a pressure lower than the pressure inside the evaporator. 2. The solvent removal method according to claim 1, wherein a falling thin film evaporator or a centrifugal thin film evaporator is used as the heating evaporator. 3. The method for removing solvent according to claim 1, wherein the solvent or low boiling point component in the product solution is removed to 1% or less using a heated evaporator.