JP2003226703A - Polymerization reaction vessel and production method of polyvinyl chloride resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polymerization reaction vessel enabling to enhance productivity by largely shortening polymerization reaction time through largely increasing cooling capacity of a reflux heat exchanger which is made to manifest performance almost close to the overall heat transfer coefficient originally possessed by the reflux heat exchanger resulting in its down-sizing, to provide a method for producing polyvinyl chloride resin by using the polymerization reaction vessel to conduct suspension polymerization or emulsion polymerization of a vinyl chloride-based monomer. <P>SOLUTION: The polymerization reaction vessel is equipped with a reflux heat exchanger the bottom and top parts of which are both connected with the vessel via each separated piping. Preferably the reflux heat exchanger is of a vertical type and multi-tube type. A condensable monomer gas in the vessel is introduced to the top part of the reflux heat exchanger passing through the piping connecting the top part of the heat exchanger and the top part of the vessel, condensing while moving downward from the top part of the heat exchanger to return to the vessel. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polymerization reaction vessel for polymerizing a condensable monomer using a reflux heat exchanger, and a chloride reaction for carrying out suspension polymerization or emulsion polymerization of a vinyl chloride monomer using the polymerization reaction vessel. The present invention relates to a method for producing a vinyl resin.
More specifically, the counterflow of the condensate flowing down and the rising condensate in the multiple tubes of the reflux heat exchanger is prevented, and a smooth flow of the condensate is prevented to prevent the overall heat transfer coefficient from decreasing. The present invention relates to a polymerization reaction vessel equipped with a reflux heat exchanger capable of downsizing and increasing cooling capacity, and a method for producing a vinyl chloride resin in which suspension polymerization or emulsion polymerization of a vinyl chloride monomer is carried out using the polymerization reaction vessel. .

[0002]

Although the present invention is not limited to the polymerization of vinyl chloride-based monomers, for example, in suspension polymerization, the vinyl chloride-based polymer is oil-soluble in an aqueous medium while stirring the vinyl chloride-based monomer. It is produced by suspension polymerization using a radical initiator. In recent years, in order to improve productivity by shortening the reaction time, a method has been adopted in which a reflux heat exchanger is installed above the polymerization reaction vessel to remove a part of the reaction heat.

The structure of the reflux heat exchanger is generally a vertical type,
It is a multi-tube type and is directly connected to the gas phase part of the polymerization reaction vessel or is connected by a pipe, and the gas to be condensed and the condensate are in the same hole or the connecting pipe, and the ascending gas flow and the descending condensate are Or a pipe that raises only the gas to be condensed is connected to the lower body cover (channel cover) of the vertical / multitubular reflux heat exchanger, and the condensed liquid is returned to the polymerization vessel without countercurrent flow. Is taken. However, in these methods, it is unavoidable that the gas to be condensed and the condensate flow in the tubes of the reflux heat exchanger, and the condensate causes liquid clogging (flooding) in the multiple tubes to reduce the adiabatic area and overall transfer. Since this causes a decrease in the heat coefficient, it is necessary to increase the size of each tube in the reflux heat exchanger, or to increase the number of tubes.

[0004]

Under the present circumstances,
The problem to be solved by the present invention is to achieve performance close to the overall heat transfer coefficient originally possessed by the reflux heat exchanger, downsize the reflux heat exchanger, and significantly increase the cooling capacity, thereby increasing the polymerization reaction time. To provide a method for producing a vinyl chloride resin in which suspension polymerization or emulsion polymerization of a vinyl chloride-based monomer is performed using the polymerization reaction vessel and the polymerization reaction vessel capable of significantly shortening the productivity. It is in.

[0005]

That is, the first invention of the present invention is a polymerization reaction vessel equipped with a reflux heat exchanger, wherein the lower part and the top part of the reflux heat exchanger are polymerized by different pipes. The present invention relates to a polymerization reaction container connected to a reaction container. A second aspect of the present invention relates to a method for producing a vinyl chloride resin, which comprises suspension-polymerizing or emulsion-polymerizing a vinyl chloride-based monomer using the above-mentioned polymerization reaction vessel.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The reflux heat exchanger of the present invention includes:
A vertical and multitubular reflux heat exchanger can be used.
The top of this reflux heat exchanger and the top of the polymerization reaction vessel are connected by a pipe (hereinafter this pipe is referred to as a gas introduction pipe). When the polymerization reaction is carried out in the polymerization reaction vessel of the present invention, the condensable monomer gas in the polymerization reaction vessel passes through the gas introduction pipe and is introduced at the top of the reflux heat exchanger, and from the top to the bottom of the reflux heat exchanger. It is condensed while moving to and is refluxed to the polymerization reaction vessel.

The circulation in which the condensable monomer gas passes through the gas introduction tube, is condensed in the reflux heat exchanger, and is returned to the polymerization reaction vessel is connected to the polymerization reaction vessel of the gas introduction tube and reflux heat exchange. When the pressure difference between the top of the reflux heat exchanger and the connection between the top of the reflux heat exchanger and the polymerization reaction vessel at the bottom of the reflux heat exchanger is smaller than that, the operation is smoothly performed. In this case, the gas introduction pipeline has a pipeline differential pressure of 20 KPa or less, preferably 10 KPa or less when the gas to be condensed flows, or the ratio L / D of the pipe length (L) to the pipe diameter (D) is set to 30 to 100. It is the preferred form.

The polymerization reaction container of the present invention is not particularly limited in other structure, shape and the like as long as the above conditions are satisfied. Usually, it is a vertically long stainless steel container having a jacket for passing cooling water to the outside or inside of the container to remove the heat of polymerization reaction. A tube-type reflux heat exchanger is installed to pass the gas to be condensed into the tube of the reflux heat exchanger, and cooling water is passed through the shell to remove heat. A pressure vessel comprising a stirrer for uniformly mixing an aqueous medium, a monomer and an oil-soluble radical initiator and a plurality of baffles from the top or bottom of the vessel.

The polymerization reaction vessel of the present invention can be used if it is a condensable monomer. Examples thereof include vinyl esters such as vinyl acetate and vinyl propionate, alkyl vinyl ethers such as methyl vinyl ether and ethyl vinyl ether, α-olefins such as ethylene and propylene, and acrylic acid copolymerizable with vinyl chloride and acrylic. Acid esters can also be used.

When used as a polymerization reaction container for suspension method of vinyl chloride monomer, vinyl chloride monomer, an aqueous medium, an oil-soluble radical initiator and the like are charged in the container and stirred to heat the polymerization reaction to the container jacket and The reaction is advanced while removing heat by a reflux heat exchanger which is an auxiliary cooler to obtain a vinyl chloride polymer. Usual polymerization conditions are a reaction temperature of 40 ° C. to 75 ° C. and a reaction time of 3 hours to 10 hours.

The position at which the condensed gas is taken out of the gas introduction pipe is
The center of the top semi-elliptical portion of the polymerization can is preferably used, but any location may be used as long as it is the top semi-elliptical portion. There may be a valve for shutting off the gas flow in the introduction pipe. The gas introducing pipe may be a double pipe through which cooling water is passed to form a liquid thin film inside the gas introducing pipe to prevent the adhesion of the polymer. Equipped with a nozzle for spraying anti-adhesion agent at the gas inlet pipe inlet,
It is effective to prevent the adhesion of the polymer even if the anti-adhesion agent is sprayed in the washing step after the polymerization, or deionized water is intermittently or continuously sprayed during the polymerization.

The finishing accuracy of the inner surface of the gas introduction pipe is electrolytic polishing E
Although it may be P-6, it may be in the state of a drawn steel pipe when the pipe is manufactured.

The polymerization reaction vessel equipped with a reflux heat exchanger in which one end of the gas introduction pipe of the present invention is connected by piping to the top of the reflux heat exchanger and the gas phase portion of the polymerization reaction vessel is Since the flow of the monomer liquid condensed in the pipe and the flow of the gas to be condensed can be made to flow in one direction without counterflowing, the condensate generated by preventing the rising gas to be condensed from trying to flow down Can be prevented from clogging in the pipe. As a result, it is possible to exhibit performance close to the overall heat transfer coefficient originally possessed by the reflux heat exchanger, downsizing the reflux heat exchanger, greatly increasing the cooling capacity, and significantly increasing the polymerization reaction time. It has become possible to improve the productivity of the resin by shortening it.

[0014]

Example 1 The bottom part of the reflux heat exchanger and the vapor phase part of the polymerization vessel were connected by a pipe having an inner diameter of 800φ, and the vapor phase part of the reactor and the top part of the reflux heat exchanger were nominally 200 A (8 inches) in length and 12 m in length. Chloride in a 100 m ³ reactor equipped with a vertical multi-tube reflux heat exchanger having a tube diameter of 25.4 mm, a number of tubes of 485, and a heat transfer area (outer diameter standard) of 150 m ² connected with a gas introduction pipe of Vinyl monomer 39m ³ , demineralized water 42.5m ³ , dispersant 750ppm
(To the monomer) and 500 ppm of the oil-soluble initiator (to the monomer) are added and stirred, and the reaction proceeds while adjusting the reaction temperature to 57 ° C, and the non-condensation in the reactor is reached before the polymerization rate reaches 25%. Open the inert gas vent valve provided at the top of the reflux heat exchanger for a certain period of time to move the gas (mainly nitrogen gas) from the polymerization reaction container and the reflux heat exchanger to the outside of the system, and prepare for the start of cooling the reflux heat exchanger. It was Then, when the polymerization rate reaches 25%, cooling water is passed through the jacket of the reflux heat exchanger,
Cooling was started. After 30 minutes from the start of cooling, the cooling amount is 80
The target value was 10,000 Kcal / Hr, and the target value of 1,400,000 Kcal / Hr was reached 20 minutes later. The amount of cooling water of the reflux heat exchanger during the reaction was 175 m ³ / Hr, the inlet water temperature was 30 ° C., the outlet water temperature was 38 ° C., and the heat removal amount of 1,400,000 Kcal / Hr was continued until 30 minutes before the reaction was stopped. , The load calorific value was gradually reduced and stopped. The reaction time was 4.5 hours. The overall heat transfer coefficient of the reflux heat exchanger was 410 Kcal / m ² · Hr · deg.

Comparative Example 1 No Gas Introducing Pipe The bottom of the reflux heat exchanger and the vapor phase of the polymerization vessel were connected by a pipe having an inner diameter of 800φ, and the pipe diameter was 25.4 m.
m, number of tubes 485, heat transfer area (outer diameter standard) 150 m ² , vertical type multitubular reflux heat exchanger with a volume of 100 m
Vinyl chloride monomer 39m ³ and demineralized water 42.5 in ³ reactors
m ³ , dispersant 750 ppm (to monomer) and oil-soluble initiator 500 ppm (to monomer) were added and stirred, the reaction proceeded while adjusting the reaction temperature to 57 ° C., and the reaction was performed before the polymerization rate reached 25%. Non-condensable gas in the vessel (mainly nitrogen gas)
The inert gas vent valve provided at the top of the reflux heat exchanger was opened for a certain period of time to move it from the polymerization reaction container and the reflux heat exchanger to the outside of the system to prepare for cooling of the reflux heat exchanger. Then, when the polymerization rate reached 25%, cooling water was passed through the jacket of the reflux heat exchanger to start cooling. Start cooling 30
After 20 minutes, the cooling amount reached 800,000 Kcal / Hr, and after another 20 minutes, the target of 14,000,000 Kcal
/ Hr to set the reflux water heat exchanger jacket cooling water amount to 1
Although increased to 75 m ³ / Hr, quantity of heat removed is 900,0
The amount of cooling water in the reflux heat exchanger changes to 175 m ³ / Hr, the inlet water temperature is 30 ° C, the outlet water temperature is 35.1 ° C, and the heat removal amount is 900,000 Kcal / hour until 30 minutes before the reaction is stopped. It was the same as Hr. After that, the amount of heat applied was gradually reduced to stop. The reaction time was 4.5 hours. The overall heat transfer coefficient of the reflux heat exchanger was 246 Kcal / m ² · Hr · deg.

[0016]

As described above, according to the present invention, by making the reflux heat exchanger exhibit a performance almost close to the general heat transfer coefficient originally possessed, downsizing the reflux heat exchanger, and greatly increasing the cooling capacity. , Greatly shortening the polymerization reaction time,
It has been possible to provide a polymerization reaction container capable of increasing productivity and a method for producing a vinyl chloride resin for carrying out suspension polymerization or emulsion polymerization of a vinyl chloride monomer using the polymerization reaction container.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a polymerization reaction vessel equipped with a reflux heat exchanger of the present invention.

[Explanation of symbols]

1: Inert gas vent line 2: Reflux heat exchanger top cover 3: Gas introduction pipe shutoff valve 4: Gas introduction pipe 5: Reflux heat exchanger 6: Polymerization can Reflux heat exchanger connection piping 7: Reflux heat exchanger Cooling water piping 8: Reflux heat exchanger bottom cover 9: Polymerization can Gas phase semi-elliptical part

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Akio Okada             Sumitomo Chemical Co., Ltd. 1-5 Anezaki Kaigan, Ichihara City, Chiba Prefecture             Business (72) Inventor, Teruyuki Suzuki             Sumitomo Chemical Co., Ltd. 1-5 Anezaki Kaigan, Ichihara City, Chiba Prefecture             Business F-term (reference) 4J011 AA01 AB03 AB15 DA01 DA03                       DB12 DB14 DB23 DB27 DB36                       JA01 JB02 JB07 JB15 KA00                       KB00

Claims (6)

[Claims] 1. A polymerization reaction container equipped with a reflux heat exchanger, wherein the lower part and the top part of the reflux heat exchanger are connected to the polymerization reaction container by different pipes. 2. The polymerization reaction container according to claim 1, wherein the reflux heat exchanger is a vertical and multitubular reflux heat exchanger. 3. A condensable monomer gas in the polymerization reaction vessel passes through a pipe connecting the top of the reflux heat exchanger and the top of the polymerization reaction vessel and is introduced to the top of the reflux heat exchanger,
The polymerization reaction container according to claim 1 or 2, wherein the reflux reaction heat exchanger is condensed from the top to the bottom while being condensed and refluxed to the polymerization reaction container. 4. The differential pressure in the pipe connecting the top of the reflux heat exchanger and the top of the polymerization reaction vessel is the connecting portion between the top of the reflux heat exchanger and the polymerization reaction vessel below the reflux heat exchanger. The polymerization reaction container according to any one of claims 1 to 3, which has a pressure difference smaller than the differential pressure. 5. The polymerization reaction container according to claim 4, wherein the differential pressure in the pipe connecting the top of the reflux heat exchanger and the top of the polymerization reaction container is 20 KPa or less. 6. A method for producing a vinyl chloride resin, which comprises suspension-polymerizing or emulsion-polymerizing a vinyl chloride-based monomer using the polymerization reaction container according to claim 1.