JP2003238615A - Method for washing chlorinated vinyl chloride resin and apparatus therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for washing chlorinated vinyl chloride resin slurry with small amount of water in a small-scale apparatus. <P>SOLUTION: This method for washing a chlorinated vinyl chloride resin comprises a first step of forming a cake layer by feeding the chlorinated vinyl chloride resin slurry to a washing tank equipped with a filtering device and filtering the slurry, a second step of feeding washing water to the cake layer from above the washing tank to wash and filter to form the cake layer again, and a third step of feeding water to the vicinity of upper part of the washed cake layer to make the chlorinated vinyl chloride resin at the lower part of the cake layer into slurry state, and thereafter taking out the washed chlorinated vinyl chloride resin slurry from the washing tank while feeding water from above the washing tank. <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 method for cleaning chlorinated vinyl chloride resin and an apparatus therefor.

[0002]

2. Description of the Related Art Chlorinated vinyl chloride resins are generally produced by chlorinating vinyl chloride resins in a water suspension state, but when chlorinating, hydrochloric acid is by-produced.

The hydrochloric acid produced as a by-product can be removed in a drying process which is a post-process, but a hydrochloric acid corrosion resistant facility and a dry exhaust hydrochloric acid treatment facility are required, which is an expensive facility. When hydrochloric acid is neutralized with a neutralizing agent, the residual metal salt after neutralization adversely affects the quality of the product, and the neutralizing agent becomes expensive, so hydrochloric acid is generally washed and removed with water. ing.

Conventionally adopted cleaning methods are a fluidized cleaning method and a decanter cleaning method. The fluidized cleaning method is a method in which the chlorinated vinyl chloride resin slurry is supplied to the cleaning tank, the cleaning water is passed from the lower part, and the hydrochloric acid drainage is overflowed from the upper part.The decanter cleaning method is the chlorinated vinyl chloride method. This is a method in which the system resin slurry is supplied to a cleaning tank, and water cleaning and centrifugation are repeated.

[0005]

However, in the case of the above-mentioned cleaning method, there is a drawback that the cleaning apparatus is large and the equipment cost is very high, and a large amount of cleaning water is required for cleaning.

In view of the above-mentioned drawbacks, an object of the present invention is to provide a cleaning method and a cleaning apparatus capable of cleaning a chlorinated vinyl chloride resin slurry with a small apparatus with a small amount of cleaning water.

[0007]

[Means for Solving the Problems] That is, the present invention provides a first step of forming a cake layer by supplying and filtering the chlorinated vinyl chloride resin slurry into a washing tank having a filtering means, and washing the cake layer. The second step of supplying washing water from the upper part of the tank, washing and filtering, and again forming a cake layer, and supplying water to the vicinity of the upper part of the filter means of the washed cake layer to chlorinated vinyl chloride at the lower part of the cake layer. After making the system resin slurry,
A method for cleaning a chlorinated vinyl chloride resin, comprising a third step of extracting a chlorinated vinyl chloride resin slurry that has been cleaned while supplying water from the upper part of the cleaning tank, from the cleaning tank.

Further, according to the present invention, the chlorinated vinyl chloride resin slurry supply pipe and the cleaning water supply pipe are installed near the upper end, and the cleaning water removing pipe is installed near the lower end in the lower part of the cleaning tank. Therefore, the filter means is installed above the cleaning water removal pipe, and the chlorinated vinyl chloride resin slurry transfer pipe having an opening is installed near the upper part of the filter means. The present invention provides a cleaning device for chlorinated vinyl chloride resin, characterized in that a water supply pipe is connected to.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION A method of cleaning a chlorinated vinyl chloride resin according to claim 1, wherein a chlorinated vinyl chloride resin slurry is supplied to a cleaning tank having a filtering means and filtered to form a cake layer. In the first step, the washing water is supplied to the cake layer from the upper portion of the washing tank, and the cake layer is washed and filtered to form the cake layer again. A chlorinated vinyl chloride resin in the lower portion of the cake layer is made into a slurry, and the third step is to extract the washed chlorinated vinyl chloride resin slurry while supplying water from the upper portion of the washing tank from the washing tank. To do.

The chlorinated vinyl chloride resin slurry used in the present invention is a slurry obtained by supplying chlorine to a suspension of the vinyl chloride resin to chlorinate the vinyl chloride resin, and is generally chlorinated. Consists of vinyl chloride resin, hydrochloric acid and water.

The above vinyl chloride resin is mainly composed of vinyl chloride monomer homopolymer or vinyl chloride monomer (5
It is a copolymer of vinyl chloride monomer and copolymerizable vinyl monomer.

Examples of the vinyl monomer include vinyl esters such as vinyl acetate and vinyl propionate; alkyl (meth) acrylate monomers such as methyl (meth) acrylate and ethyl (meth) acrylate; olefins such as ethylene and propylene; (Meth) acrylic acid,
Examples thereof include maleic anhydride, acrylonitrile, styrene and vinylidene chloride.

The first step in the present invention is a step of forming the cake layer by supplying and filtering the above chlorinated vinyl chloride resin slurry into a washing tank having a filtering means.

A filter medium is generally used as the filtering means. Any filter medium may be used as long as it can filter the chlorinated vinyl chloride resin, for example, woven fabric, non-woven fabric,
Examples thereof include glass fiber, wire mesh, perforated metal plate, and ceramic porous body.

In the above washing tank, it is preferable that the filtering means is provided below the washing tank. Since hydrochloric acid is present in the slurry, it is preferable that the washing tank is made of an acid resistant material.

When the chlorinated vinyl chloride resin slurry is supplied to the washing tank, it is filtered by the filtering means to remove water and hydrochloric acid, and a cake layer is formed on the filtering means.

The second step in the present invention is to form a cake layer,
This is a process of supplying washing water from the upper part of the washing tank, washing and filtering, and forming a cake layer again. This step is performed once or multiple times until the hydrochloric acid in the cake layer is removed.

When filtered, the water level in the cake layer gradually decreases. If the washing water is supplied when the water level of the cake layer is high, the hydrochloric acid in the cake layer diffuses into the washing water and the washing effect decreases, so the water level in the cake layer is 5
It is preferable to supply the washing water after the water has dropped by not less than cm.

In the third step of the present invention, water is supplied near the upper part of the filter means of the washed cake layer to make the chlorinated vinyl chloride resin in the lower part of the cake layer into a slurry, and then water is washed from the upper part of the washing tank. Is a step of extracting the chlorinated vinyl chloride resin slurry that has been washed from the washing tank while supplying.

The washed chlorinated vinyl chloride resin needs to be extracted and dried, but since the caked chlorinated vinyl chloride resin cannot be easily extracted,
Slurry again and extract.

If water is supplied to the caked chlorinated vinyl chloride resin from the upper portion, it takes time to form the slurry and it is difficult to extract it. Therefore, water is supplied near the upper portion of the cake layer filtering means to lower the cake layer. After making the chlorinated vinyl chloride resin of (1) into a slurry form, water is supplied from the upper part of the washing tank to make a slurry form and the slurry is extracted.

In order to extract the chlorinated vinyl chloride resin in the form of a slurry, it may be extracted with a pump or pressurized from the upper part of the washing tank, but the extraction pipe is provided near the upper part of the filtering means. That is, it is preferable that the chlorinated vinyl chloride resin at the bottom of the cake layer is opened and extracted at a position where the resin is slurried.

In the cleaning device for chlorinated vinyl chloride resin according to claim 2, a chlorinated vinyl chloride resin slurry supply pipe and a cleaning water supply pipe are installed near the upper end, and a cleaning water removal pipe is installed near the lower end. In the cleaning tank in which the filter is installed, the filtering means is installed in the lower part and above the cleaning water removing pipe, and the chlorinated vinyl chloride resin slurry transfer pipe having an opening is installed in the vicinity of the upper part of the filtering device. The water supply pipe is connected to the chlorinated vinyl chloride resin slurry transfer pipe.

The cleaning device for chlorinated vinyl chloride resin is a cleaning device suitable for carrying out the cleaning method according to the first aspect. The cleaning apparatus of the present invention will be described with reference to the drawings. FIG. 1 is a schematic view showing an example of the cleaning device of the present invention.

In the figure, reference numeral 1 is a cleaning tank having an inner surface coated with titanium. A chlorinated vinyl chloride resin slurry supply pipe 2 connected to a chlorinated vinyl chloride resin reaction tank (not shown) through a valve 21 at the upper end of the cleaning tank 1, and a washing water through a valve 31. The supply pipe 3 is connected.

Reference numeral 4 is a cleaning water removing pipe installed at the lower end of the cleaning tank 1, and a valve 41 is installed in the middle of the cleaning water removing pipe 4. 5 is a filter medium, and a cleaning tank 1
Inside, it is installed above the cleaning water removal pipe 4.

Numeral 6 is a chlorinated vinyl chloride resin slurry transfer pipe installed so that the opening 62 is located in the vicinity of the upper portion of the filter medium 5. The chlorinated vinyl chloride resin slurry transfer pipe 6 is provided with a valve 61. Connected to a drying device (not shown).

Reference numeral 7 is a water supply pipe connected to the washing water supply pipe 3 via a valve 71 and to the opening 62 side of the chlorinated vinyl chloride resin slurry transfer pipe 6 from the valve 61.

Reference numeral 8 denotes a nitrogen supply pipe installed in the upper part of the cleaning tank 1, and is connected to a nitrogen cylinder (not shown) via a valve 81.

Next, a method of cleaning the chlorinated vinyl chloride resin with the above cleaning device will be described. First, the valves 31, 6
1 and 81 are closed, valves 21 and 41 are opened, and the chlorinated vinyl chloride resin slurry supply pipe 2 is connected to the cleaning tank 1.
A chlorinated vinyl chloride resin slurry is supplied to.

The supplied chlorinated vinyl chloride resin slurry is filtered by the filter medium 5, a cake layer is formed on the filter medium 5, and the filtered water is removed from the cleaning water removing pipe 4. At this time, it is preferable to open the valve 71 a little so that the hydrochloric acid water does not enter the chlorinated vinyl chloride resin slurry transfer pipe 6 and continue to flow the cleaning water little by little.

Next, the valve 21 is closed and the valve 31 is opened, washing water is supplied from the washing water supply pipe 3 to the cake layer to wash the chlorinated vinyl chloride resin, and the cake layer is formed again by filtration. To do. The washing water is supplied once or plural times until the hydrochloric acid is removed from the chlorinated vinyl chloride resin.

As described above, it is preferable to supply the wash water after the water level in the cake layer has dropped from the surface of the cake layer by 5 cm or more. During this step, the chlorinated vinyl chloride resin slurry transfer pipe 6 is also provided. It is preferable to open the valve 71 a little and keep flushing water flowing little by little so that it does not enter into.
Further, in order to carry out filtration quickly, the valve 81 may be opened to supply nitrogen and pressurize.

The washed chlorinated vinyl chloride resin is transferred to a drier and dried. To transfer the chlorinated vinyl chloride resin, first close valves 31 and 41 and loosen valve 71 to increase the supply amount of cleaning water. The cake in the vicinity of the opening 62 of the chlorinated vinyl chloride resin slurry transfer pipe 6 is slurried.

Next, the valve 71 is closed and the valve 31 is opened to supply washing water to make the entire cake layer into a slurry. Simultaneously with or immediately after opening the valve 31, the valve 61 is opened to transfer the reslurried chlorinated vinyl chloride resin slurry to the drying device through the chlorinated vinyl chloride resin slurry transfer pipe 6.

The slurry may be transferred by providing a pump in the chlorinated vinyl chloride resin slurry transfer pipe 6 or by opening the valve 81 and pressurizing with nitrogen.

[0037]

Since the method for cleaning a chlorinated vinyl chloride resin according to claim 1 is as described above, the chlorinated vinyl chloride resin slurry can be cleaned with a small amount of cleaning water in a small apparatus. it can.

Since the cleaning device for chlorinated vinyl chloride resin according to claim 2 is as described above, the device is small and the equipment cost is low, and the cleaning can be efficiently performed with a small amount of cleaning water. You can

[0039]

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a cleaning device of the present invention.

[Explanation of symbols]

1 cleaning tank 2 Chlorinated vinyl chloride resin slurry supply pipe 3 Wash water supply piping 4 Cleaning water removal piping 5 filter media 6 Chlorinated vinyl chloride resin slurry transfer pipe 7 Water supply piping

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Claims (2)

[Claims] 1. A first step of supplying and filtering a chlorinated vinyl chloride resin slurry into a washing tank having a filtering means to form a cake layer, the washing water is supplied to the cake layer from the upper part of the washing tank, Second step of washing and filtering to form a cake layer again, and water is supplied to the washed cake layer near the upper part of the filtering means to make the chlorinated vinyl chloride resin in the lower part of the cake layer into a slurry, and then washed. A method for cleaning a chlorinated vinyl chloride resin, comprising a third step of extracting from the cleaning tank a chlorinated vinyl chloride resin slurry that has been cleaned while supplying water from the upper part of the tank. 2. A cleaning water which is a lower part of a cleaning tank in which a chlorinated vinyl chloride resin slurry supply pipe and a cleaning water supply pipe are installed near the upper end and a cleaning water removal pipe is installed near the lower end. The filtration means is installed above the removal pipe, and the chlorinated vinyl chloride resin slurry transfer pipe with an opening is installed near the upper part of the filtration means. Water is supplied to the chlorinated vinyl chloride resin slurry transfer pipe. Cleaning equipment for chlorinated vinyl chloride resin, which is characterized by connecting pipes.