The mainly advantage of this system is the possibility to adjust the Moisture level in the soap. This is used to obtain finished soap with the required TFM. The Vacuum Drying Plant, also called soap dryer, was invented in Italy in the middle of the last century; this system revolutionized the soap industry, allowing large productions with little manpower.
The soap that come out from a saponification plant, after being filtered, is pumped to the Vacuum Drying Plant through the Heat exchanger by means of Soap feed pump. Production rate of the plant is determined by the speed of this pump. This soap is sprayed on the wall of the Atomizer. Conditions inside are such that the sprayed soap dries, cools down, and is immediately scraped off the wall. Evaporated moisture is conveyed through vapor ducts and cyclones to the Barometric condenser, by means of a Vacuum Pump, where all the vapours are condensed by direct contact with the water from cooling tower. All this waterfall, through barometric leg, into the Hot Well. Eventual un-condensable, such as air, are sucked by a Liquid ring Vacuum Pump group. During passage through the Cyclones, vapours are separated from entrained soap dust which is gathered at the bottom of the Cyclones and transferred from second to first cyclone by Fines Screw Conveyor. From there it is recycled into the Atomizer by another Fines Screw Conveyor. Some Vacuum Drying Plant works with only one cyclone.
Scraped soap falls at the worms of the Plodder that can be simplex or duplex, and is extruded in the form of noodles.
In case of pure or filled laundry soap production Heat Exchanger is by passed since it is not necessary to pre evaporate any moisture. For this type of soap the vacuum levels obtainable by this vacuum group are not enough. It becomes necessary to use a Booster,hat will guarantee ulterior pressure drop.
Booster is also necessary if cooling water available exceeds 26°C.
In laundry soap manufacturing the Atomizer is assembled on duplex vacuum plodder; the first stage refines the soap, while the second stage extrude a soap bar that is cut & printed by means of a soap cutter.
The moisture % is adjusted playing with the temperature of the heat exchanger and the vacuum level. A neat soap (semi-boiled or full boiled) with a TFM of 58-60% can be easily concentrated up to 78-80%, removing many points of moisture inside the neat soap.