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FBR March 2016

34 | MARCH 2016 | FOOD & BEVERAGE REPORTER www.fbreporter.com VAPOUR CURSE ... Continued from previous page Abbott recommends that a coalescing filter be installed upstream from the dryer to remove any compressor oil and other contaminants that may still be trapped in the compressed air. Another option is a membrane dryer, which use hollow fibers through which water vapour passes easily, but is difficult for air (oxygen and nitrogen) to pass through. When humid compressed air reaches the membrane, the water vapour permeates it and is drawn to the outside due to a pressure differential in the the hollow fibers. The compressed air becomes dry and flows out. The system allows for continuous de- humidification. By altering the air flow rate and membrane configurations, pressure dew points up to -60°C can be achieved, says Abbott. Desiccant dryers, on the other hand, pass air through beds of desiccant, an absorbent material such as silica gel or activated alumina, which adsorb water vapour to its surface to effectively lower dew points to temperatures well below that which a refrigerated dryer can achieve. Heatless regenerative models use a pair of desiccant beds which alternate in service; while the one bed is operational, the off-line bed is regenerated via a pressure swing adsorption process. Pressure dew points from a standard -30°C to an optional -50°C and beyond can be achieved with a desiccant dryer. Both membrane and desiccant dryers are adversely affected by the presence of oils or liquid water and must be protected with a quality coalescing filter. What is the appropriate dew point? Abbott says over-specifying an applicationor a facility dew point can be very expensive due to high energy costs, just as the maintenance costs for water vapour damage to product lines can be for an under-specified dew point. He says drying the entire factory’s compressed air supply to -30°C dew point is unnecessary and wasteful. It is more sensible to dry the compressed air to a dew point -10°C lower than the factory’s lowest ambient temperature and then subdivide the compressed air supply by application, using zone or point-of-use membrane or desiccant dryers to provide the appropriate level of dryness. The costs of energy, downtime, replacing components, end product defects or even loss of brand value are just a few factors to consider when determining an appropriate dew point. For more info on dryers, visit www.smcpneumatics.co.za Exclusive supplier info@heatandcontrol.com Cape Town +27 21 948 5934 ® www. U R S C H E L .com SPRINT 2™ DICER ®Urschel&DiversaCutSprintareregisteredtrademarksofUrschelLaboratories,Inc.U.S.A.™Sprint2trademarkpending. Merging the Cutting Advances and Features from the DiversaCut Sprint® and the Model G The Sprint 2™ Dicer combines the legendary Model G Dicer footprint and similar infeed/discharge heights with the cutting advances offered by the popular DiversaCut Sprint® Dicer. The dicer offers a convenient solution for food processors seeking to replace their existing Model G, G-A, GK-A, H, or H-A Dicer. The Sprint 2 Dicer produces a wide variety of dices, granulations, slices, and strips of vegetables, fruits, bakery products, meats, and seafood. The cutting principle is based on the DiversaCut Sprint technology turned at an adjusted angle. Meet us @B31 Cape Town +27219485934

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