CN212758588U - Device for adding dispersing agent during production of PVC resin - Google Patents

Abstract

The utility model discloses a device for adding dispersant during PVC resin production, which comprises a dispersant storage tank, a dispersant outlet pipeline, a conveying pipeline and a return pipeline, wherein the bottom of the dispersant storage tank is provided with a dispersant outlet, the dispersant outlet is connected with the first end of the dispersant outlet pipeline, and the second end of the dispersant outlet pipeline is respectively connected with the first end of the conveying pipeline and the first end of the return pipeline through a tee pipe; be equipped with the circulating pump on the return line, the second end of return line is connected with the top of dispersant storage tank, makes dispersant solution beat the top of dispersant storage tank through the circulating pump from the bottom of dispersant storage tank, so circulate just can accomplish with the stirring paddle leaf contact in the dispersant storage tank, no dead angle to make the concentration of dispersant solution even, avoid appearing concentration layering phenomenon, and then make the particle diameter evenly distributed of the PVC resin of producing, reduce the appearance of large granule PVC resin.

Description

Device for adding dispersing agent during production of PVC resin

Technical Field

The utility model discloses the totality belongs to polyvinyl chloride industry technical field, more specifically relates to a device of adding dispersant when producing PVC resin.

Background

Polyvinyl Chloride (PVC) resin is a polymer compound obtained by polymerizing Vinyl Chloride (VCM) Monomer. PVC resin is a synthetic material that is currently well appreciated, popular and also widely used, and polymerization methods thereof generally include solution polymerization, bulk polymerization, emulsion polymerization and suspension polymerization. Each polymerization method has different application ranges due to the technical improvement and the change of objective requirements, and suspension polymerization is a main production mode of PVC resin due to simple production process, convenient control, convenient large-scale production and strong product adaptability, and the PVC resin produced by the suspension polymerization method accounts for about 80 percent of the total yield.

The suspension polymerization is characterized in that a dispersing and heat transfer medium is acted by water, auxiliary agents such as a dispersing agent and an initiator and vinyl chloride monomer are added into an aqueous solution system, reactants are dispersed at high degree under the action of stirring of reaction raw materials to form stable emulsion, the vinyl chloride monomer is dispersed in tiny liquid drops, each liquid drop is equivalent to a polymerization system, the initiator dissolved in the monomer is decomposed into free radicals at the polymerization temperature to initiate the polymerization of the vinyl chloride monomer, the whole polymerization process comprises unit reactions such as chain initiation, chain growth, chain termination and the like, and a terminator is added to stop the polymerization reaction after a preset conversion rate is reached, so that the stable PVC resin is obtained.

The dispersing agent has the functions of reducing the interfacial tension of the VCM monomer and water and being beneficial to dispersing the VCM monomer under the stirring action on the one hand, and the dispersing agent is adsorbed on the surface of the liquid drops to play a role in protection and prevent the mutual aggregation or combination of the liquid drops when the liquid drops are formed on the other hand. The dispersant generally consists of a multi-component dispersion system compounded by hydroxypropyl methyl cellulose and one or more polyvinyl alcohols with different alcoholysis degrees, and the main properties of the PVC resin product, such as apparent density, porosity, particle shape, particle size distribution, fish eye disappearance speed, hot processing melting time, monomer residual content and the like, are influenced by the combined components, the combined proportion and the solution concentration of the dispersant.

Qinghai salt lake magnesium industry Co, Ltd PVC&The potash plant adopts suspension polymerization to produce SG5 (wherein S represents suspension polymerization, G represents general-purpose resin, and 5 represents viscosity classification number) type PVC resin, including acetylene method PVC device and ethylene method PVC device, wherein the acetylene method PVC productivity is 46 ten thousand tons/year, two production lines are provided, each production line has 3 pieces of 143m³The polymerization kettle is a single kettle.

However, since the material feeding and trial production, the particle size distribution of the produced PVC resin is not uniform enough, and the particle size is large, which seriously affects the quality of the PVC resin. In order to ensure the product quality of the PVC resin and guarantee the high-quality rate, the first-class rate and the qualified rate, the influence reasons of people, machines, raw materials, methods and the like in the production process of the PVC resin are analyzed one by a brain storm analysis method according to a fishbone diagram, and the fact that the particle size distribution of the produced PVC resin is not uniform enough due to the fact that the concentration of the added dispersing agent is not uniform when the PVC resin is produced is determined.

The synthesis of PVC resin is carried out in a polymerization kettle, and before the dispersing agent is added into the polymerization kettle, a dispersing agent solution with a specific concentration needs to be prepared in a dispersing agent storage tank, and then the dispersing agent solution is input into the polymerization kettle according to needs. However, in the prior art, the dispersant storage tank is designed to be stirred at the upper part, and cannot be changed into stirring at the lower part from the structure, and the stirring paddle is arranged at the central position of the dispersant storage tank, so that a dead angle which is difficult to stir exists in the dispersant storage tank, the dispersant solution cannot be completely contacted with the stirring paddle, and the concentration stratification phenomenon occurs. The concentration of the dispersant solution has a layering phenomenon, which can cause that the concentration of the dispersant is still uneven when the dispersant solution is input into a polymerization kettle, thereby causing the problems that the particle size distribution of the produced PVC resin is not uniform enough and the particle size is larger.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a device of dispersant adds during production PVC resin to among the solution prior art, dispersant solution has the phenomenon of concentration layering in the dispersant storage tank, and the PVC resin of the production that leads to appears particle size distribution not enough even, the great problem of particle diameter.

In order to solve the technical problem, the utility model adopts the following technical scheme: a device for adding a dispersing agent during production of PVC resin comprises a dispersing agent storage tank, a dispersing agent outlet pipeline, a conveying pipeline and a return pipeline, wherein a stirring paddle is arranged in the dispersing agent storage tank and used for stirring a dispersing agent solution in the dispersing agent storage tank; a solution delivery pump is arranged on the delivery pipeline, and the second end of the delivery pipeline is connected with the polymerization kettle so as to input the dispersant solution in the dispersant storage tank into the polymerization kettle; and the return pipeline is provided with a circulating pump, and the second end of the return pipeline is connected with the top of the dispersing agent storage tank, so that a closed loop is formed between the return pipeline and the dispersing agent storage tank to circulate the dispersing agent solution in the dispersing agent storage tank.

Preferably, the dispersant storage tank consists of a cylindrical barrel body positioned at the upper part and a conical barrel bottom positioned at the lower part and connected with the bottom of the cylindrical barrel body, and the dispersant outlet is arranged at the tip part of the conical barrel bottom.

Preferably, an outlet valve is arranged on the dispersant outlet pipeline, an output valve is arranged at the position in front of the pump of the conveying pipeline, and a return valve is arranged at the position in front of the pump of the return pipeline.

Preferably, a sampling branch pipe is arranged on the dispersant outlet pipeline, and a speed regulating valve is arranged on the sampling branch pipe.

Compared with the prior art, the utility model provides a pair of add device of dispersant when producing PVC resin has following advantage: through the outside at the dispersant storage tank increase return line and circulating pump, make dispersant solution beat the top of dispersant storage tank through the circulating pump from the bottom of dispersant storage tank, so the circulation just can accomplish with the stirring paddle leaf contact in the dispersant storage tank, no dead angle to make the concentration of dispersant solution even, avoid appearing concentration layering phenomenon, and then make the particle diameter evenly distributed of the PVC resin of producing, reduce the appearance of large granule PVC resin.

Drawings

Fig. 1 is a schematic structural diagram of a first embodiment of the present invention.

Fig. 2 is a schematic structural diagram of a second embodiment of the present invention.

Detailed Description

The preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, wherein like reference numerals refer to like elements and techniques of the present invention so that advantages and features of the present invention may be more readily understood when implemented in a suitable environment. The following description is an embodiment of the present invention, and other embodiments related to the claims that are not explicitly described also fall within the scope of the claims.

Fig. 1 shows a schematic structural diagram of a first embodiment provided by the present invention.

The device is used for preparing a dispersant solution required by PVC resin production, and the dispersant solution needs to be input into a polymerization kettle to participate in polymerization reaction after being configured in the device in advance.

As shown in fig. 1, this device of dispersant is added during production PVC resin, including dispersant storage tank 1, dispersant outlet pipeline 2, conveying line 3 and return line 4, be equipped with stirring paddle 5 in the dispersant storage tank 1, a dispersant solution for in the dispersant storage tank 1 stirs, the upper portion of dispersant storage tank 1 is equipped with the motor 6 of drive stirring paddle 5, the bottom of dispersant storage tank 1 is equipped with dispersant export 11, dispersant export 11 is connected with the first end of dispersant outlet pipeline 2, the second end of dispersant outlet pipeline 2 is connected with conveying line 3's first end and return line 4's first end respectively through tee bend pipe fitting 7.

The delivery pipe 3 is provided with a solution delivery pump 81, and a second end of the delivery pipe 3 is connected with a polymerization kettle (not shown in the figure) to deliver the dispersant solution in the dispersant storage tank 1 into the polymerization kettle. The circulating pump 82 is arranged on the return pipeline 4, and the second end of the return pipeline 4 is connected with the top of the dispersing agent storage tank 1, so that a closed loop is formed between the return pipeline 4 and the dispersing agent storage tank 1, and the dispersing agent solution in the dispersing agent storage tank 1 is circulated.

In this embodiment, through increase return line 4 and circulating pump 82 in the outside of dispersant storage tank 1, make dispersant solution beat the top of dispersant storage tank 1 through circulating pump 82 from the bottom of dispersant storage tank 1, at configuration dispersant solution in-process, this circulating pump 82 can be launched always, so the circulation just can make the stirring paddle leaf contact in dispersant solution and the dispersant storage tank 1, no dead angle, thereby make the concentration of dispersant solution even, avoid appearing the concentration layering phenomenon, and then make the particle size evenly distributed of the PVC resin of producing, reduce the appearance of large granule PVC resin.

Dispersant storage tank 1 comprises the cylindrical barrel 12 that is located upper portion and the conical barrel head 13 that is located the lower part and is connected with the bottom of cylindrical barrel 12, and the tip of conical barrel head 12 is located to dispersant export 11, and this kind of design can make things convenient for dispersant solution thoroughly to discharge, and then promotes the circulation of dispersant solution, avoids appearing the dead angle phenomenon.

An outlet valve 91 is provided in the dispersant outlet line 2, an outlet valve 92 is provided in the delivery line 3 at a position before the pump, and a return valve 93 is provided in the return line 4 at a position before the pump.

At the beginning of preparing the dispersant solution, the outlet valve 91 is closed, the dispersant and a specific proportion of water are added into the dispersant storage tank, and the stirring motor 6 is started to drive the stirring blade 5 to start stirring. After the dispersing agent is suspended in the water, the output valve 92 is closed, the outlet valve 91 and the reflux valve 93 are opened, the circulating pump 82 is started, the dispersing agent solution in the dispersing agent storage tank 1 is circulated, the dispersing agent is uniformly mixed, and then the dispersing agent solution with consistent concentration is prepared. Before the dispersant solution is fed into the polymerization reactor, the dispersant solution in the bottom of the dispersant storage tank 1 is sampled and analyzed for the concentration within the normal index range, and after the concentration is determined to be within the normal index range, the output valve 92 is opened, the solution feed pump 81 is started, and the feeding operation is started.

Fig. 2 shows a schematic structural diagram of a second embodiment provided by the present invention.

As shown in FIG. 2, in order to facilitate sampling, a sampling branch pipe 10 is additionally provided to the dispersant outlet line 2, and a speed control valve 94 is additionally provided to the sampling branch pipe 10. Before feeding, the speed regulating valve 94 is opened, and the dispersant solution flows out from the water outlet of the sampling branch pipe 10 for sampling analysis.

After the reaction of each kettle is finished, taking the slurry to analyze the particle size distribution. According to the national standard GB/T5761-2006 suspension method universal polyvinyl chloride resin, different types of PVC resins are included, in this embodiment, only SG5 type PVC resin is taken as an example, and the comparison table of the mass fraction of PVC screen wastes and the product grade is shown in the following table.

The above lists show that the screened material fractions of the obtained PVC resin reach the excellent grade after 10 times of tests, and the expected effect is achieved. Through the improvement of a device for adding the dispersing agent, the quality high-grade product rate of the produced PVC resin is obviously improved, the reject rate is reduced to 1 percent from 10 percent, 4.185 million tons of unqualified products can be reduced according to the annual output of 46.5 million tons, and the economic profit can be increased by 8370 million yuan.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

Claims (4)

1. A device for adding a dispersing agent during the production of PVC resin is characterized by comprising a dispersing agent storage tank (1), a dispersing agent outlet pipeline (2), a conveying pipeline (3) and a return pipeline (4),

a stirring paddle (5) is arranged in the dispersing agent storage tank (1) and is used for stirring dispersing agent solution in the dispersing agent storage tank (1), a motor (6) for driving the stirring paddle (5) is arranged at the upper part of the dispersing agent storage tank (1), a dispersing agent outlet (11) is arranged at the bottom of the dispersing agent storage tank (1), the dispersing agent outlet (11) is connected with a first end of a dispersing agent outlet pipeline (2), and a second end of the dispersing agent outlet pipeline (2) is respectively connected with a first end of a conveying pipeline (3) and a first end of a return pipeline (4) through a tee pipe fitting (7);

a solution delivery pump (81) is arranged on the delivery pipeline (3), and the second end of the delivery pipeline (3) is connected with the polymerization kettle so as to input the dispersant solution in the dispersant storage tank (1) into the polymerization kettle;

be equipped with circulating pump (82) on return line (4), the second end of return line (4) is connected with the top of dispersant storage tank (1), makes form a closed loop between return line (4) and dispersant storage tank (1), in order to right dispersant solution in dispersant storage tank (1) circulates.

2. The apparatus for adding a dispersing agent in the production of PVC resin according to claim 1, wherein the dispersing agent storage tank (1) is composed of a cylindrical tub body (12) at an upper portion and a conical tub bottom (13) connected to the bottom of the cylindrical tub body (12) at a lower portion, and the dispersing agent outlet (11) is provided at a tip of the conical tub bottom (13).

3. The device for adding the dispersing agent in the production of the PVC resin according to claim 2, wherein the outlet valve (91) is arranged on the dispersing agent outlet pipeline (2), the output valve (92) is arranged at the position before the pump of the conveying pipeline (3), and the return valve (93) is arranged at the position before the pump of the return pipeline (4).

4. A device for adding dispersant in the production of PVC resin according to any of claims 1-3, characterized in that a sampling branch pipe (10) is provided on the dispersant outlet pipeline (2), and a speed regulating valve (94) is provided on the sampling branch pipe (10).

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