| 摘要 |
1337312 Dissolving residues from equipment GAF CORP 2 July 1971 [24 July 1970] 31185/71 Heading F2N [Also in Division B1] Residues accumulated on the surfaces of chemical apparatus, e.g. polymeric residues on the surfaces of polymerization equipment, are contacted with a residue-solvent comprising N-methyl pyrrolidone at a temperature of between 70‹ C. and 150‹ C., the residue-containing solvent then being discharged from the apparatus. The apparatus may be filled with the solvent, which is agitated until the residues are dissolved. Alternatively, the solvent may be streamed over the residue-bearing surfaces of the apparatus. Alternatively, the solvent may be discharged from spray heads located in the upper regions of the apparatus, dissolved residue and dislodged particles of residue then collecting with the solvent in the lower part of the apparatus, where the dislodged particles dissolve. The collected residue-containing solvent may then be pumped back to the spray heads. Recirculation continues until all the residue is dissolved. The apparatus may be heated during the cleaning time. The temperature of the solvent is preferably between 80‹ and 125‹ C. and ideally between 90‹ and 105‹ C. The volume of solvent used is at least 10%, e.g. 25%, of the volume of the apparatus. After treatment with the solvent, the apparatus may be sprayed with water. The solvent is used until the dissolved residues reach a certain concentration; the solvent is then regenerated. Regenerating the solvent.-In a first stage evaporator, the solvent and water are boiled off. The remaining viscous solution is treated in a second stage evaporator, which is mechanically aided to permit the removal of further amounts of solvent and water. The water is then separated from the solvent in a fractionating column. Before the evaporating stages, the residues may be precipitated by adding the residue-containing solution to 20-50% by volume of water. |
