JPS5852301A - Method and device for preventing scale adhesion to the inner walls of polymerization vessels, etc. - Google Patents

Abstract

PURPOSE:To apply antiscales onto the inside wall or a like area of a polymerization vessel so as to secure easy and safe application by use of a small amount of the coating solution, by applying the antiscales onto the inside wall by spraying them by means of an applicator provided within the upper portion of the polymerization vessel. CONSTITUTION:From a two-fluid (liquid/gas) spray nozzle-fitted applicator 2 provided within the upper portion of a polymerization vessel 1 equipped with an agitator, antiscales (liquid) stored in a tank 3 and passed therefrom via a pump 4, a valve 5 and a pressure control valve 6 are sprayed so as to coat the inside wall, agitator, etc., of the vessel with them. On the other hand, a gas is supplied via a valve 7 and a pressure control valve 8. Examples of the gas which can be suitably used include air, nitrogen, ethane, propylene, methyl chloride and Freon 13. As the antiscales there can be mentioned those having a scale preventing effect, such as dyes and polar organic compounds. These compounds are used after dissolution in a suitable medium.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for applying a scale inhibitor to the inner wall of a polymerization vessel, etc., and a polymerization apparatus in which a scale inhibitor coating device is incorporated in the polymerization vessel.

Conventionally, known methods for combining monomers such as vinyl monomers or diene monomers include turbidity polymerization, emulsion polymerization, solution polymerization, gas phase polymerization, and bulk polymerization. However, in all of these polymerization methods, there was a melting point during the polymerization process scale adhesion on the inner wall of the polymerization vessel and other parts of the stirring device.

In other words, when vinyl monomers are polymerized using these methods, 1-coal scale is deposited on the inner wall of the polymerization vessel, the stirring device, and other parts that come into contact with the monomers, which reduces the yield of the polymerization method and the cooling capacity of the polymerization vessel. In addition to this, this scale flakes off and mixes into the product, reducing the quality of the product. On the other hand, it takes excessive effort and time to remove this scale. Not only is this scale necessary, but unreacted monomers are adsorbed in this scale, so there is a risk of injury to the human body due to monomers (vinyl chloride, etc.), which has become a very serious problem in recent years. There is a disadvantage.

In order to solve the problem of melting point during scaling, it has been known to apply a scale preventive agent to the inner wall of the polymerization vessel, the stirring device, etc. A method of applying a polar organic compound, dye, pigment, etc., a method of applying a polar organic compound or dye treated with gold cormorant salt, a method of applying a mixture of an electron-donating compound and an electron-accepting compound, or A method is known in which an aqueous solution in which an alkali metal or ammonium salt of a sulfonic acid type or carboxylic acid type dye is dissolved is adjusted to pH 7Pl and then applied.

However, as specific means for implementing these coating methods, there are methods such as filling a container with the coating liquid and then drawing it out, and spraying the coating liquid, but the former method does not cause polymerization. This has the disadvantage that it is impossible to use it repeatedly in large numbers because it gets mixed into the drying fabric liquid filled with water and the like. On the other hand, with the spray application method, the coating solution is not contaminated by residual compounds or water, so the coating solution can be constantly applied according to the prescription, and there is no need to waste. Pigeon advantages.

However, this spray application is carried out from a manhole or the like of one container. Therefore, in today's world where the danger of human injury caused by monomers has become a major problem, opening manholes is problematic and there is a strong demand for closed system operation, or at least for operation using an automatic dispensing method. In order to define this, the present inventors previously developed a polymerization device incorporating a coating device that can automatically and uniformly apply a scale inhibitor to the inner wall of the polymerization vessel, stirring device, etc.; proposed that the droplets ejected from the nozzle have a diameter of 1,000 μm or more and should be applied in a squall-like manner, so a large amount of coating agent would be used, and excess coating liquid or its cleaning water should be disposed of. There is a drawback that wastewater treatment must be carried out due to coloration or BOD. Furthermore, since this coating device uses a single-fluid spray, there is a problem in that if the diameter of the droplets is made into a fine spray, the flying distance will be lost and the coating efficiency will be reduced.

The present invention has solved these drawbacks. Let's prevent scale from forming on the inner walls of the chassis! The purpose is to provide a fabric method and a polymerization device incorporating a scale prevention IFII coating device in the polymerization vessel, and the gist is as follows.

1. Liquid installed at the top of a 1-mixer with a stirrer.
Apply the scale preventive agent #J111 from a coating device with a two-flow spray nozzle to apply the scale preventive agent to the inside of the polymerization reactor, stirrer, etc. #Method of applying anti-scaling agent to the inner wall of the polymerization vessel, etc. where mold grows.

2. A polymerization apparatus that incorporates a scale inhibitor coating device equipped with a liquid-gas two-fluid pays nozzle in the upper part of the polymerization vessel equipped with a stirrer.

According to the present invention, the scale preventive agent can be applied uniformly with a small amount of coating liquid without leaving any uncoated area, and the coating time is automatically applied within a few seconds to several tens of seconds. Therefore, the operation of applying the scale preventive agent to each polymerized patch or every few patches can be performed very easily and safely, and the desired excellent scale preventive effect can be obtained.

The present invention will be explained in detail below.

In the present invention, a scale preventive agent (liquid) is sprayed as fine atomized droplets of 1 to 100 microns from a liquid-gas two-fluid spray nozzle coating device installed in the upper part of the polymerization vessel with a stirrer, and is applied to the inner wall of the polymerization vessel. , agitator, etc., and instantly dries on the coated surface to form an anti-scaling coating.

Figure 1 shows the outline of a polymerization apparatus incorporating such a coating device, where 1 is a 1-coating vessel, 2 is a coating device installed in the upper part of the polymerization vessel 1, and 8 is a storage for scale preventive agent (coating liquid). 4 is a pump, 5゜7 is a pulp, 6 is a coating liquid pressure adjustment valve, 8 is a gas pressure adjustment valve, 9 is a water injection pump for preventing clogging of the nozzle hole of the coating device during application, 10 is a valve that is kept closed when applying scale prevention III. Is the coating device in Figure 2? This is a sugar schematic diagram showing one embodiment of the present invention, in which a two-fluid spray nozzle 11 is installed to finely atomize the scale inhibitor (@heavy liquid) with gas.

゛The structure of the coating device V2 is not limited to the annular one illustrated in the drawing, but the important thing is to uniformly apply the scale preventive agent to the inner wall of the polymerization vessel, the stirrer, etc., as well as the blind areas of the jar 7 plate, etc. For spraying of the coating liquid, use the siphon spray method in which the scale preventive agent (G body) is sucked up through a nozzle or fed by gravity. However, 1 ton of scale preventive material (M body) is fed into the nozzle under pressure, and the scale preventive agent and gas are mixed inside to create a finely atomized spray.By the pressure spray method, the inner wall of the polymerization vessel, the stirring shaft, etc. on the surface of! It will be revealed. Pressure sprayers are industrially preferred because they can transport liquid in a stationary manner.

Finely atomized spray can be flown at any distance depending on the gas pressure, so by arranging the spray nozzle so that it can coat the entire interior of the container, it can be applied to blind spots where it was previously difficult to apply. The coating can be applied all over the back side of the jammer plate or the stirring shaft.

The fine spray needs to be dried instantly on the inner wall of the polymerization vessel, and for this purpose a method is used in which the inner wall of the polymerization vessel is heated in advance. Although heating depends on the type of solvent used in the scale inhibitor, it is usually carried out at a temperature in the range of 40 to 95°C. In addition, in order to perform these processes more efficiently, a method of spraying under reduced pressure is also used.

When the coating solution is completely dried, it is carried out by aeration after coating or by drying under reduced pressure.

As a result of the above method, the present invention improves coating efficiency, resulting in a significant reduction in the amount of coating required. Therefore, there is no need for drainage treatment for excess coating liquid, and after spraying, preparation can be started without draining.

One of the other features of the present invention is scale prevention JIJ17)
In order to fully demonstrate the scale prevention effect, the scale inhibitor must be sprayed dissolved in the solvent. Therefore, the severity of the gas depends on the N type of the solvent for the scale inhibitor, but it is usually sprayed at temperatures between room temperature and 95°C. The temperature of the coating solution is such that the anti-scaling compound 1 is dissolved in the solvent, and is usually in the range of room temperature to 95°C.

Suitable gases used for the above purpose include: gust, l[
, -M carbonized carbon collection, ammonia, methane, ethane, butane,
Isobutane, ethylene, propylene, butadiene, acetylene, vinyl chloride, methyl chloride, freon 13. Examples include Freon 12, Freon 22, methyl ether, and methylamine.

The present invention is advantageously applied to the polymerization of vinyl chloride, etc., and in this case, the use of vinyl chloride as the gas has the advantage that the first reaction operation can be easily carried out in a closed system. It will be done.

-1. The scale inhibitor that can be used in the present invention may be any conventionally known one, including dyes, polar organic compounds, sulfur compounds, and polymer compounds that have been proposed to exhibit scale prevention effects. All of these are included, and one or more of these can be used by dissolving one or more of them in a suitable medium in advance. This medium (solvent)
For closing, L type solvents or a mixture of two or more types of solvents such as water, alcohol solvents, ester solvents, ketone solvents, hydrocarbon solvents, and chlorinated hydrocarbon solvents are used. The dissolved concentration of scale inhibitor in these media is 0.01 to 3
It is desirable that the amount of N be approximately 0.1-1%, particularly around 0.1-1%.

The desired coating is carried out by supplying the above-mentioned gas and scale pressure agent (!? fabric heavy liquid) to the coating device, and the gas supply pressure at this time is usually preferably in the range of 2 to 20 IF/+? is preferably 3 to 109/j, and the supply pressure of the coating liquid is set in relation to the coating amount, but is usually in the range of 2 to 20 KP/-, preferably 3 to 8 KP/j.
- is better. The amount of coating solution applied varies depending on the concentration of the scale inhibitor, but is generally 0.01 J/nI.
Or 1. Oj/TII, preferably 0.03j/T
d to 0.2 J/l#. By doing this, a scale-preventing coating film is formed on the surface of the inner wall of the polymerization vessel, etc.

The coating device with a two-fluid spray nozzle is installed in the upper part of the polymerization vessel, and although it is important to avoid contacting the nozzle opening with the liquid in the merging phase, it is necessary to
In order to prevent blockage of the IJJ theory nozzle, send water,
It is desirable to let the water come out little by little from the nozzle opening. This water injection starts when the polymerization raw materials are charged,
After the 1° polymerization is completed, the reaction is preferably carried out continuously until the combined slurry is taken out. In a general industrial-scale polymerization reactor, the amount of water at this time is approximately 0.0117 min to 1 min.
0! / divided.

After the coating of the scale preventive agent on the inner wall of the polymerization vessel and other areas where the car body comes into contact is completed, add the water liner, vinyl or diene monomer to this vessel in the usual manner, and start the process. and other necessary additives, such as monomer dispersion aids, are charged and polymerized.

Specific examples of the above monomers include vinyl chloride, vinyl acetate, vinyl propionate, acrylic acid, methacrylic acid or their esters or salts, maleic acid or fumaric acid, and their esters or anhydrides, butadiene, chloroprene. ,.

Examples include isoprene, ethylene, acrylonitrile, vinylidene halide, and vinyl ether.

Further, conventionally known dispersion aids, polymerization initiation agents, etc., which are added to the polymerization system, are used.

Next, specific examples will be shown.

Example 1 Acid Black 14 was made into an aqueous solution of 0.3% by weight, and the pH was adjusted to 2.5 with futic acid to prepare a scale inhibitor coating solution.

The jacket humidity of a polymerization vessel made of Step 3 with an internal volume of 130 mm was raised to 50°C, and the internal pressure was 1600 smHg.
Reduce the pressure until it reaches the figure below, and place a
Install the device I (with a two-fluid spray nozzle) and send the scale prevention coating liquid at a pressure of 6 (/-).
7Kp/cd of vinyl chloride monomer heated to gasification at ℃
It was atomized by sending it at a pressure of 10 J.

After coating, without drying or washing with water, prepare the following weight ratio (total amount of preparation: 11011/
), polymerization was carried out at 57°C for 7 hours.

Chloride and nil monomer 100 parts by weight water
130 #Partially saponified polyvinyl alcohol 0.04 -Hydroxypropyl methylcellulose 002 〃G2-1CHA'
V''<0.04 During one cup of #-oxyv dicarbonate, water was supplied to the coating device at a rate of 2 rpm according to FIG. 1, and polymerization was carried out while pouring water from the nozzle port.

After the completion of the first polymerization, the contents of the polymerization vessel were taken out, and the interior of the polymerization vessel was washed with water while the system remained closed.

The above polymerization operation is considered as one patch, and polymerization is repeated 600 times.
When patching was carried out, no blockage of the nozzle was observed, and no scale was observed on the inner wall of the polymerization vessel, the stirrer, or the jammer plate.

Example 2 Oil black was made into a 0.2% by weight trichlorethylene solution, and this was made into a scale prevention It coating solution.

The coating device shown in Figures 1 and 2 was installed in the upper part of the stainless steel coating container with contents fill 0001, and the above scale prevention coating liquid 0.2! was applied from the coating nozzle. 4IP/
When the mixture was fed at a pressure of - and applied using a sudden blast of air at a pressure of 5/d, the inner surface of the polymerization vessel was coated uniformly. After this coating, the jacket temperature was raised to 90° C. and dried for 5 minutes.

Spray water from the nozzle of the applicator to 0. OtJ! The operation of pouring water into the polymerization vessel at a rate of 1/min was started.

Next, charge the following weight ratio into this polymerization vessel (
Total amount of preparation (9007), heated at 70℃ for 7 hours and further at 80℃
I let it run for 2 hours.

Styrene 70 Lid Acrylonitrile 30 #Water
120 #Hydroxyapatite 0.5 #Sodium lauroyl sulfate 0.01 It Prauyl peroxide 0.35 #After the reaction was completed, the contents of the polymerization platform were taken out and the interior of the polymerization vessel was washed with water, but no scale was observed.

When the above operation was performed as one batch and polymerization was repeated, no scale adhesion or nozzle clogging was observed even after 30 batches were performed.

[Brief explanation of the drawing]

wllllJ schematically shows a coating device incorporating a coating device, and FIG. 2 is a schematic diagram showing one embodiment of the coating device. DESCRIPTION OF SYMBOLS 1...Polymerization vessel, 2...Holly cloth device, 8...Scale prevention 11J (coating liquid) storage tank, 4...Pump, 5.7...' Pulp, 6...Coating Liquid pressure adjustment valve, 8...Gas pressure adjustment valve, 9...Water injection pump, 10...Valve kept closed when anti-scaling agent is clouded, 11...Two-fluid spray nozzle.

Claims (1)

[Claims] 1. Liquid installed in the upper part of the polymerization vessel equipped with a stirrer.
The scale preventive agent is sprayed from a gaseous two-fluid spray nozzle coating device to the inner walls of the polymerization reactor and the inner walls of the polymerization reactor, etc. Fabric method 1 Scale prevention 1lF11a equipped with a liquid-gas two-fluid mist nozzle at the top of the polymerization vessel with a stirrer
Polymerization equipment incorporating 15 devices