GB470419A - Improvements in or relating to cleaning the interiors of enclosed spaces by volatilegrease solvents - Google Patents

Abstract

The interior surfaces of tanks, condensers and similar enclosed spaces are cleaned with volatile solvents, by introducing the solvent into the space in both vapour and liquid form, and subsequently removing the liquid solvent containing the impurities. A fuel-tank car 4 containing bituminous and tarry deposits is first treated with steam to loosen the deposit to some extent to permit, removal through an outlet. Solvent vapours are then admitted through a line 15 having discharge nozzles 16, from a vaporizer 14 connected to a tank of <PICT:0470419/III/1> trichlorethylene 9. The condensed solvent and impurities are pumped into a sump 24 and after removal of supernatant water are pumped through a line 29 to jets 60, 61 in the tank car which may be tilted if desired. Air containing some vapour which is initially displaced from the tank car passes through a condenser 20 to the atmosphere. The jets of liquid solvent and solvent vapour may be supplied simultaneously or alternately after which a final vapour rinse is effected. A proportion of the used solvent passes from the sump 24 into a still 51 from which solvent vapours may be returned to the tank car during the cleaning operation or pass to a condenser 20 to recover the solvent which returns to the storage tank 9. Any liquid solvent in tank car is removed by tilting and draining. Solvent vapours contained in the warm tank car, are forced into the condenser 20 by a blower 46 from which air is forced through a heater 14 and pipe 15. During this stage the car may be heated internally or externally. Final traces of solvent may be removed by steam. After passing through the condenser the heated air may be treated with an adsorbent such as silica, silica gel or alumina gel. In a modification, two stills and condensers are employed, whereby solvent recovery proceeds simultaneously with the generation of solvent vapours, and a gas holder to contain the initially displaced air is provided. Trichlorethylene may be replaced by carbon tetrachloride, ethylene dichloride, perchlorethylene, or b -trichlorethane. Specification 315,930, [Class 91], is referred to.