JP2003183309A - Vinyl chloride polymerization reactor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vinyl chloride polymerization reactor capable of preventing scale accumulation inside and thereby dispensing with the labor of removing the accumulated scale for manufacturing a high-quality polyvinyl chloride smoothly. <P>SOLUTION: The reactor wherein a polyvinyl chloride is manufactured by suspension polymerization has (A) a fixed structure inside, (B) a water spraying unit to be inserted into the reactor for cleaning all inner walls, capable of three-dimensional spraying of water with the sprayer capable of vertical movement, and (C) another water spraying unit to be inserted into the reactor for cleaning the structure referred to in (A), capable of two-dimensional spraying of water with the sprayer capable of vertical movement. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reaction vessel for producing a vinyl chloride monomer by suspension polymerization. More specifically, the present invention is excellent in that scale accumulation in a polymerization reaction vessel can be prevented, and thus the work involved in cleaning and removing accumulated scale can be eliminated, and a high-quality vinyl chloride can be produced smoothly. The present invention relates to a vinyl chloride polymerization reaction vessel having features. [0002] A vinyl chloride polymer is produced by subjecting a vinyl chloride monomer to suspension polymerization in an aqueous medium using an oil-soluble radical initiator while stirring. here,
Structures such as a baffle, a stirring shaft, a capacitance type liquid level meter, and an additive pipe are installed in the polymerization reaction vessel, and scale adheres to such structures and accumulates over time. The accumulated scale peels off during the polymerization and is mixed as a foreign substance into the vinyl chloride product, which causes a problem of deteriorating the quality of the product. Therefore, it is necessary to periodically clean and remove the scale, but in order to sufficiently remove the scale, it is necessary to take time to wash with water or to remove the scale manually, which is problematic in terms of work efficiency. [0003] Under such circumstances,
The problem to be solved by the present invention is to prevent the accumulation of scale in a polymerization reaction vessel, thereby eliminating the work involved in cleaning and removing the accumulated scale, and enabling smooth production of high-quality vinyl chloride. It is an object of the present invention to provide a reaction vessel for producing a vinyl chloride polymer having excellent characteristics. That is, the present invention relates to a reaction vessel for producing a vinyl chloride monomer having the following features (A) to (C) by a suspension polymerization method. is there. (A): having a structure fixed inside the container (B): a water spray device inserted into the container and for cleaning all wall surfaces inside the container, wherein water is three-dimensionally (C): a water spray device for cleaning the structure of (A) above, which is inserted into the container and cleans the structure of (A) above. The present invention has a device for spraying water and moving a spray portion up and down. DETAILED DESCRIPTION OF THE INVENTION The polymerization reaction vessel of the present invention has a structure fixed inside the vessel. Examples of the structure include a baffle, a stirring shaft, a capacitance type liquid level meter, an additive pipe, and the like. [0006] The polymerization reaction vessel of the present invention is a water spray apparatus inserted into the inside of the vessel, for cleaning the entire wall surface inside the vessel, and sprays water three-dimensionally, and the spray portion is vertically moved. Which has a device that moves to Spraying water two-dimensionally means rotating 360 degrees in the horizontal direction. Sprays suitable for such use are commercially available. The number of nozzles from which water is ejected may be one to a plurality of six. In order to move the spray part up and down,
For example, the hose winder may be driven to drive the spray nozzle attached to the tip of the hose up and down, or the spray nozzle at the rod end of a cylinder driven by water pressure, hydraulic pressure or air pressure may be attached and driven up and down. [0008] The polymerization reaction vessel of the present invention satisfies the above conditions, and there are no other restrictions on the structure, shape, etc., but usually it is as follows. That is, it is a vertical cylindrical container made of stainless steel, which has a jacket through which cooling water passes inside or outside the container to remove polymerization reaction heat, or a reflux type that supplementarily removes reaction heat. A pressure vessel equipped with a heat exchanger and equipped with a stirrer (wings and shaft) and a plurality of baffles from the top or bottom of the vessel to uniformly mix the aqueous medium, monomer and oil-soluble radical initiator. A capacitance level meter that detects the foaming height of the contents generated during the reaction and a pipe for injecting additives are also provided at the top of the container, while the polymer adhering to the container after polymerization is sprayed using a high-pressure water spray nozzle. An apparatus for washing with water is also provided at the top of the container. The polymerization vessel of the present invention is a polymerization vessel for suspension polymerization of a vinyl chloride monomer. That is, a vinyl chloride-based monomer, an aqueous medium, an oil-soluble radical initiator, and the like are charged into the container, and the reaction is carried out while removing the heat of the polymerization reaction under stirring with a jacket to obtain a vinyl chloride-based polymer. The usual polymerization conditions are a reaction temperature of 40 ° C. to 75 ° C. and a reaction time of 3 hours to 10 hours. The greatest feature of the present invention resides in that a two-dimensional spray and a three-dimensional spray are combined, and a structure for intensively cleaning the vicinity of a structure where scale is easily accumulated by the two-dimensional spray is employed. In the three-dimensional spray, it takes about 5 minutes to return to the original position because the trajectory of the cleaning point moves. Therefore, although the number of times spray water is applied to the location where the scale has accumulated is small, the entire inner surface of the polymerization vessel is washed in a mesh form. The two-dimensional spray is stopped on the horizontal plane where the scale has accumulated, and by selecting an appropriate number of nozzles and rotation speed, spray water can be applied to the place where the scale adheres at least 20 times per minute. With such a structure, the problem to be solved by the present invention can be completely solved. The jet pressure of the spray is usually 15 MPa
３５35 MPa. Cleaning inside the container by spraying
It is preferably carried out each time the polymerization of each batch is completed. [0012] EXAMPLE 1 baffle 4 a, volume 100 m ³ reactor of vinyl chloride monomer 39m ³ provided with a reflux heat exchanger as an auxiliary cooler having an inner jacket, deionized water 42.5M ³ , Dispersant 7
00 ppm (based on monomer) and 500 pp of oil-soluble initiator
m (with respect to the monomer), and the mixture was stirred. The reaction was completed in 4.5 hours while controlling the reaction temperature to 57 ° C., and the unreacted monomer and polymer were taken out of the reactor to a subsequent step. 3D nozzle with nozzle and 2 with 2 nozzle
The reactor was washed with water using a water spray washing device combined with a D nozzle. The 3D nozzle was sprayed with water by concentrating the baffle support and the gas-liquid interface so that the trajectory of the sprayed water was reticulated from the nozzle over the entire inner surface of the container. The time required for the water spray cleaning was 15 minutes. After the washing, the operation was shifted to the preparation operation of the next batch, and the operation of causing the polymerization reaction to proceed as described above and then washing again with water spray was repeated. As a result, the reaction vessel could continuously produce 1200 batches for one year without stopping production for local removal of polymer. [0013] Comparative Example 1 four baffles, volume 100 m ³ reactor of vinyl chloride monomer 39m ³ provided with a reflux heat exchanger as an auxiliary cooler having an inner jacket, deionized water 42.5M ^3, dispersant 7
00 ppm (based on monomer) and 500 pp of oil-soluble initiator
m (with respect to the monomer), and the mixture was stirred. The reaction was completed in 4.5 hours while controlling the reaction temperature to 57 ° C., and the unreacted monomer and polymer were taken out of the reactor to a subsequent step. The reactor was washed with water using two sets of 3D nozzle-equipped water spray washer. The two sets of 3D nozzles were sprayed with water so that the water sprayed from the nozzles hit the entire inner surface of the container in a checkerboard shape and washed. After the washing, the operation was shifted to the preparation operation of the next batch, and the operation of causing the polymerization reaction to proceed as described above and then washing again with water spray was repeated. As a result, a local polymer remains on the baffle support of the reaction vessel, and grows to repeat the polymerization reaction operation.
After 200 batches per month, the particle size distribution of the polymer began to change, and after 250 batches over 2.5 months, fisheye in the product increased. Therefore, the production was stopped, the reactor was opened to remove the deposits, and a manual removal operation was performed. The removal operation lasted for 48 hours, and the weight of the removed polymer was 250 kg. Although the production was resumed after removing the deposits, the 200A ball valve at the bottom of the reactor was clogged with polymer lumps during the production after 300 batches for three months, and the polymer slurry could not be removed from the container.
The removal operation required 12 hours. As described above, according to the present invention, the accumulation of scale in the polymerization reaction vessel can be prevented, and the work involved in cleaning and removing the accumulated scale can be eliminated. Thus, a vinyl chloride polymerization reaction vessel having an excellent feature that it can be produced was provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an example of a diagram showing an overview of a polymerization reaction vessel of the present invention. [Description of Signs] 1 Container body 2 2D spray 3 3D spray 4 Baffle

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Akio Okada             5-1, Anesaki Beach, Ichihara City, Chiba Prefecture Sumitomo Chemical             Industry Co., Ltd. (72) Inventor Kenichi Shinohara             5-1, Anesaki Beach, Ichihara City, Chiba Prefecture Sumitomo Chemical             Industry Co., Ltd. F term (reference) 4J011 DA03 DB24 EA06 EC02 JB24                       JB26

Claims (1)

Claims: 1. A reaction vessel for producing a vinyl chloride monomer having the following features (A) to (C) by a suspension polymerization method. (A): having a structure fixed inside the container (B): a water spray device inserted into the container and for cleaning all wall surfaces inside the container, wherein water is three-dimensionally (C): a water spray device for cleaning the structure of (A) above, which is inserted into the container and cleans the structure of (A) above. Have a device for spraying water and moving the spray part up and down