In the manufacture of sugar, the container of the sugarcane juice is connected to a vacuum pump. Why?
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Abstract: Rotary drum vacuum filters have been widely used in sugar and a variety of other industries for
many years. They are well suited to applications where both dewatering and washing are required and appear to be the best of the available equipment for the treatment of cane sugar muds. In this article discussed about vacuum filter description, its operational parameters and also explained optimization of filter cake pol (sugar loss from vacuum filter).
Mud Mixer or bagacillo mixerThe mud to filters flows by gravity from the clarifier to mixer or by pump. In mixer fitted with sttirrer, bagacillo from mill baggase carrier is fed continuously to the mixer. The mixture of mud and bagacillo is continuously feed to the mud trough of filter. The RPM of the mixer is around 20 to 25.Mud Trough & Agitator
The mud and bagacillo mixture is continuously feed to mud trough from the mud mixer. It is a semi cylindrical in shape. In order to avoid allowing the muds in the filter tank to settle out, they are kept in movement by an agitator oscillating to and fro, pivoted on the axis of the filter, and driven by a separate small motor.Rotary Filter DrumThe filter drum rotates around horizontal axis is always partially submerged in the mud trough. It is horizontal cylinder with corrugated surface. Which is covered by fine copper or s. s. screens. The screen has 625 perforations per sq. inch. with 0.5mm dia and 23% clear opening area.Filtrate Receiving VesselAll segment tubes are united in trunnion valve through which filtrate withdrawal pipes are drawn and led to filtrate connecting vessels under vacuum. One vessel for heavy and other for light filtrate. Low vacuum maintained through control valve. Top side is connected to vaccum pump for extraction of air and vapour to create vacuum. Bottom side pipes are immersed in the sealing tank.Vacuum Pump & CondenserVaccum pump create vaccum inside the system. it’s capacity is about 18 meter cu air suction per square meter of filter area. The condenser condenses the vapour sucked from the filtrate the pump located near treated juice receiving tank.As per Peter Rein Approximately for 100m2 filter area required Vacuum pump capacity – 520 to 680L/sec and Condenser cross section area- 0.48m2 required. Entrainment Separator
Entrainment into the filter condenser is not normally a problem if the filtrate tank cross-section area is sufficiently large, the filtrate entries directed tangentially downwards into the tank, and the gas vent to the condenser taken from the highest point in the tank. However, vacuum Leaks in the filtrate pump seals and tanks have to be avoided. Some sources recommend that filtrate pipes be of corrosion-resistant material, and that a generous head drop be
arranged between the filtrate receivers and the filtrate pumps.