| 摘要 |
In a process of dry cleaning using perchlorethylene solvent and a detergent and recycling the solvent after filtering, the solvent passing through the filter is maintained at a degree of water saturation of not more than 50% and an acid number of not more than 0.16. The detergent may be a petroleum sulphonate salt. Impurity may be removed from the solvent to control its acid number by distilling a portion of the solvent and/or by adding a non-caking adsorbent to the solvent before the filter. The adsorbent may be magnesium oxide, magnesium silicate, absorbent carbon, or diatomaceous earth. p In the embodiment of Fig. 1 (not shown), used solvent is discharged from coin-operated machines 10 and 12 through filter baskets 28 and 30 into a tank 26 fed with adsorbent through inlet 70. From tank 26 it is pumped to a filter tank 48 having inlet pressure gauge 60. The filtered solvent passes through an outlet pressure gauge 62 and a constant flow valve 50 to a storage tank 14 for reuse after recycling through a bed of decolorizer 54. A rise in pressure of gauge 62 to a predetermined value indicates need for renewal of the filter. Water and residual solvent are removed from hot drying air in a condenser 32 and the solvent recycled from a water separator 34. |
