JPH11116536A - Reactor for continuous esterification - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a thermosiphon type reactor for continuous esterification which is capable of preventing short passage of unreacted matter which is contained in an esterified product to send the next step. SOLUTION: The reactor, which allows circulation of the reaction mixture in an esterification reactor 1 by equipping a heat exchanger for heating 2 outside the reactor by the thermosiphon effect, is obtained by fitting a plurality of separation plates 3 which are spirally linked along the vertical axis of the reactor in the esterification reactor 1 in such a way that adjacent separation plates overlaps when viewed from the top (or bottom).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous esterification reaction apparatus capable of preventing a short path of an unreacted substance contained in an esterification reactant to be sent to a next step.

[0002]

2. Description of the Related Art In recent years, a thermosiphon type reactor having a heat exchanger for heating outside has been used as a reactor for a reaction requiring a large temperature rise or a reaction with a large heat load such as an endothermic reaction.
It is used in many manufacturing processes and has the following advantages. 1. Since stirring is performed by thermal driving, mechanical stirring is not required, and energy costs can be reduced. 2. Since the heat exchanger is provided outside the reaction tank, the heat transfer area can be freely designed. 3. The structure of the reaction tank can be simplified as compared with a method in which heating is performed by a jacket or an internal coil.

When such a reactor is used as a continuous esterification reactor, for example, when terephthalic acid and ethylene glycol are continuously esterified and then polycondensed to produce polyethylene terephthalate. If the number of complete mixing type reaction tanks is small, a large amount of unreacted raw material is discharged from the reaction product outlet, and there is a problem that the operability of the next process and the quality of the final product are deteriorated.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a thermosyphon type continuous esterification reactor having an external heat exchanger for short-circuiting unreacted substances contained in an esterification reactant sent to the next step. An object of the present invention is to provide a continuous esterification reactor capable of preventing a pass.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems. The gist of the present invention is to provide a heat exchanger for heating outside and circulate the reactants in the esterification reaction tank by the thermosiphon effect. In the continuous esterification reaction device, two or more partition plates spirally connected around the vertical central axis of the reaction tank are connected to the esterification reaction tank, and the adjacent upper and lower partition plates are vertically aligned. A continuous esterification reaction apparatus provided with an overlapping portion.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic explanatory view showing an example of the continuous esterification reaction apparatus of the present invention, wherein 1 is an esterification reaction tank, 2 is a heat exchanger, 3 is a partition plate, 4 is a supply pipe for a heat medium, and 5 is A heat medium discharge pipe, 6 is a raw material supply pipe,
Reference numerals 7 and 8 denote pipes for circulating the reactants, 9 denotes a pump for extracting the reactants, and 10 denotes a distillation column.

The raw material supplied from the raw material supply pipe 6 merges with the reactant circulating in the reactant circulation pipe 7 and is heated in the heat exchanger 2, and then the ester is supplied from the reactant circulation pipe 8. Into the reaction tank 1. In the esterification reaction tank 1, the reactant flows through a flow path formed by two or more partition plates 3 while reacting, and is sent out to a reactant circulation pipe 7. Then, a part of the reactant is withdrawn by the reactant withdrawal pump 9 and sent to the reactor in the next step. At this time, by setting the position where the reactant is withdrawn away from the material supply position,
Short paths for unreacted substances can be eliminated.

In the apparatus according to the invention, the circulation of the reactants is
Heating to a temperature higher than that of the esterification reaction tank 1 in the heat exchanger 2 causes a decrease in the density of the reactant, generation of bubbles, and the like, which occurs when the reactant flows upward.

In the present invention, the esterification reactor 1
In addition, two or more partition plates spirally connected around the vertical central axis of the reaction tank, provided so that the adjacent upper and lower partition plates have a portion vertically overlapped,
Since the reactants flow down spirally from the top to the bottom between the partition plates, the circulation cycle becomes longer.

The partition plate 3 needs to be installed so that the flow path extending to the bottom of the esterification reaction tank 1 below the connection portion of the reactant circulation pipe 8 is long.

The sectional area of the partition plate 3 in the horizontal plane is preferably at least 70% of the sectional area of the reaction tank. If it is less than this, the effect of extending the circulation cycle by the partition plate becomes insufficient.

It is necessary that the upper and lower partition plates have overlapping portions. If the reactants do not have overlapping parts, regardless of the compartments separated by the partition plate,
It flows directly from the connection between the reactant circulation pipe 7 and the reaction tank 1 to the bottom of the reaction tank 1, and the effect of the partition plate is lost.

Further, it is necessary that two or more partition plates are spirally connected. If the number of the partition plates is less than this, the effect of extending the circulation cycle by the partition plates becomes insufficient.

The device according to the invention is particularly suitable for terephthalic acid (TP
It is preferably used for a continuous esterification reaction between A) and ethylene glycol (EG).

[0015]

According to the present invention, in a thermosiphon-type esterification reactor having a heat exchanger for heating outside, two or more partition plates spirally connected to an esterification reaction tank are overlapped with each other in a vertical direction. Since it is installed so as to have, the circulation cycle, that is, the reaction time can be lengthened, and a short path of unreacted substances contained in the esterification reactant to be sent to the next step can be prevented.

[0016]

Next, the present invention will be described in detail with reference to examples. In addition, the measuring method of a characteristic value etc. is as follows. (a) Unreacted TPA amount The esterification reaction product was dissolved in hexafluoroisopropanol, the undissolved material was separated, and the weight was measured. (b) Esterification reaction rate An acid value AV and a saponification value SN were determined by the following method, and were calculated by the following formula. Esterification reaction rate (%) = (1-AV / SN) × 100 AV: The esterification reaction product was dissolved in dioxane and titrated with a methanol solution of sodium hydroxide. SN: The esterification reaction product was saponified with an ethanol solution of sodium hydroxide under reflux for 2 hours, and the excess sodium hydroxide was determined by back titration with hydrochloric acid. (c) Circulation cycle Inject dye at a certain point in the raw material supply pipe during raw material supply,
The time required for the coloring of the extracted reaction product to be visually confirmed was measured.

Examples 1 to 4 and Comparative Examples 1 to 2 In the apparatus shown in FIG. The cross-sectional area in the horizontal plane was set so as to have a ratio (area ratio) shown in Table 1 with respect to the cross-sectional area of the reaction tank 1. In the esterification reactor 1 where bis (β-hydroxyethyl) terephthalate and its low polymer are present, TPA 1
A slurry having a ratio of 00 mol / h and 120 mol / h of EG was continuously supplied, and an esterification reaction was carried out at a temperature of 260 ° C. and a residence time of 7 hours. At this time, the temperature of the heat medium supplied to the heat exchanger 2 was set to 270 ° C. Table 1 shows the circulation state of the reactants and the characteristic values of the esterification reactants.

[0018]

[Table 1]

[0019]

According to the present invention, in a thermosiphon-type esterification reactor having a heat exchanger for external heating, short paths of unreacted substances contained in the esterification reactant to be sent to the next step are prevented. A continuous esterification reactor is provided.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing one example of a continuous esterification reaction apparatus of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Esterification reaction tank 2 Heat exchanger 3 Partition plate 6 Raw material supply piping 7, 8 Reactant circulation piping 9 Reactant extraction pump

Claims (1)

[Claims] 1. A continuous esterification reactor in which a heat exchanger for heating is provided outside and a reactant in an esterification reaction tank is circulated by a thermosiphon effect. A continuous esterification reaction apparatus comprising two or more partition plates spirally connected around an axis so that adjacent upper and lower partition plates have a vertically overlapping portion.