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METHOD FOR PRESSURE AND RESIDUE DEGASSING OF A PVC-WATER MIXTURE IN THE POLYMERIZATION AUTOCLAVE AT THE HIGHEST POSSIBLE SEPARATION DEGREE OF THE TRANSMISSION IN A ADDITIONAL SEPARATOR AND RETURN OF THE TRANSMISSION TO THE RESTOURY
METHOD FOR PRESSURE AND RESIDUE DEGASSING OF A PVC-WATER MIXTURE IN THE POLYMERIZATION AUTOCLAVE AT THE HIGHEST POSSIBLE SEPARATION DEGREE OF THE TRANSMISSION IN A ADDITIONAL SEPARATOR AND RETURN OF THE TRANSMISSION TO THE RESTOURY
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机译:在附加分离器中以最大可能的分离度将聚合高压釜中的PVC-水混合物进行压力和残渣脱除的方法
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摘要
In the process for reducing the residual vinyl chloride monomer in an aqueous polyvinylchloride dispersion comprising the steps of depressurizing an aqueous polyvinylchloride dispersion containing emulsifiers and/or protective colloids as obtained from pressure polymerization in a polymerization zone, subjecting the same to a vacuum with heating, passing the gasses and foam of liquid constituents resulting from said depressurizing step and said vacuum treating step to a confined space wherein said gasses are separated from liquid constituents, and recovering an aqueous polyvinylchloride dispersion having a reduced residual vinyl chloride monomer content, the improvement consisting in passing said gasses and foam of liquid constituents to a confined space having a volume of not more than 331/3% of the volume of said polyvinylchloride dispersion and returning said foam of liquid constituents to said polyvinylchloride dispersion in said polymerization zone through an elongated zone of small cross-section below said confined space and at such a rate that said confined space is never completely filled with said foam of liquid constituents. According to the invention, the amount of liquid or foam accumulating in the confined space is pumped back into the degassing (polymerization) autoclave by means of a pump arranged underneath the confined space. The advantages consist in a better utilization of the separating capacity, a better and more uniform degassing of the product, and shorter degassing cycles.
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