Patent GB-690874-A (GB)
Title: Improvements in or relating to dry cleaning apparatus
IPC: D06F43/08
Filed: 1950-04-04
Abstract: <PICT:0690874/III/1> In a dry cleaning process wherein residual solvent is recovered from the drained cleaned goods by steam-distillation under reduced pressure, the supply of steam to the vessel containing the drained goods is automatically controlled, e.g. by pressure-responsive electrical switch, to maintain the pressure in the vessel at the desired low value, e.g. 5" Hg. absolute. The temperature of the cooling water supplied to the condenser, and the pump withdrawing condensate from the condenser, may also be controlled by the same pressure-responsive means.  The soiled goods are introduced into perforated drum 14 mounted in a casing 12 which is connected by pipe 64 to jet condenser 66.  The solvent is supplied to the drum 14 and casing 12 through pipes 48, 46. The drum is rotated in bearings 38, 42 by motor 28, the direction of rotation being periodically reversed.  Longitudinal ribs 26 are mounted on the inner cylindrical surface of the drum to lift and tumble the goods. When the washing has been completed, the solvent is pumped out through pipe 58, and the speed of rotation of the drum is increased to cause additional solvent to separate from the goods by centrifugal action.  After solvent has been drained off in this manner, valve 60 is closed and the system is evacuated by pump 90.  The speed of rotation of the drum is now reduced to a value sufficient to distribute the goods uniformly therein.  When the casing 12 has been evacuated down to the desired level, diaphragm-operated control switch 104 closes automatically; and steam is admitted to the casing through pipes 52 and 46, the solenoid-operated steam-valve 56 being energized and opened by the closing of switch 104.  This switch 104 also starts up pump 72 which withdraws condensate and cooling water from condenser 66, and energizes thermostat 107 which controls the temperature of the cooling water supplied to to the condenser through pipe 68.  The steam vaporizes the residual solvent from the goods in drum 14, and the mixed vapours are passed to the condenser.  The condensed solvent is withdrawn from separator 78 through pipe 80.  A portion of the water from separator 78 is returned through pipe 68 to the condenser, and the remainder is discharged through pipe 84. Fresh cooling water is admitted to pipe 68 from pipe 86, the quantity being regulated by valve 88 which is governed by thermostat 107.  If for any reason the pressure within casing 12 rises above the value that causes switch 104 to open, the steam-valve 56 and water-valve 88 are automatically closed, and pump 72 is shut down.  The condenser (see Fig. 2) contains a cylindrical condensing chamber 122 in which are mouted three water-sprays 124.  The condenser is connected to vacuum pump 90 through pipe 92.  The vapours to be condensed are introduced into the top of the condenser through pipe 64.  The water supply pipe 68 is connected with the sprays 124 via pipe 126 and channel 128.  The lower end of pipe 126 is provided with a valve 130 which is controlled by float 142 which floats in a layer of liquid at the bottom of the condenser. Liquid is discharged from the condenser through connection 156. The float 142 limits the liquid-content of the condenser, and acts as a safety-device to prevent liquid passing through pipe 92 to the vacuum pump.  In order to prevent the building-up of excessive differences between chamber 122 and space 127, and the accumulation of water in space 127, when the condenser is first brought into operation and discharge pump 72 is not in operation, a liquid-seal 146 is provided between them by an open-top chamber 150 containing water, and a baffle 152 extending down into the water.  Chamber 150 communicates with the interior of chamber 122 through an opening 148, and is continuously supplied with water from one of the sprays 124 so as to maintain the surface of water in chamber 122 level with the bottom of opening 148, when the condenser is operating normally.  During the initial period of evacuation, a large volume of air is sucked into the condenser, but when a relatively small pressure difference has been built up between chamber 122 and space 127, the water is blown out of seal-chamber 150 and the air flows through opening 148, and thence through pipe 92 to the vacuum-pump.  Specification 649,785 is referred to.