Drying equipment film dryers

Fig. 2. Double-drum dryer (uttiiospheriei. Dryers of this type handle a variety of food products of widely varying densities and viscosities dilute solutions, heavy liquids, or pasty materials. A number of products can be dried successfully with this kind of configuration, inasmuch as exposure to temperature above the boiling point is restricted to just a few seconds. The movable dram permits effective control over product film thickness. Feed may be hy perforated lube mrngh. pendulum, or various special configurations. (Bufiovah Division. Blau -Knox hunt dc Chemical Equipment, Inc)...

The wiped-film evaporator is a special type of evaporator that permits evaporation to a much higher concentration of solids than do other evaporators. Liquid is fed into a heated cylinder that contains rotating blades or wipers to reduce the liquid to a film, thereby improving the heat-transfer efficiency. Wiped-film evaporators can also be operated as dryers. Other equipment that can be used for drying and calcining non-high-level waste is the same as for HLW, e.g., spray calciners, fiuidized-bed calciners, and rotary kilns. 

According to Nijhuis et al. (1996), freeze drying (known as a suitable dehydration process for pharmaceutical and food products) is not suitable for the production of homogeneous films because the films obtained are generally very spongy. Also, a freeze-dried product tends to be porous and the problem of rapid rehydration may arise once the product is exposed to a more humid environment. Moreover freeze drying is very energy intensive. The equipment is also more expensive than atmospheric pressure dryers. It is best suited for heat-sensitive materials, or when solvent recovery is required, or if there are risks of fire and/or explosion. 

Solvent is recovered in two steps. 90% of the solvent is recovered in a scraped film evaporator (FI). The remaining 10% of the volatiles are recovered by a degassing extruder (El) equipped with a pelletizer. The pellets are cooled with water. The cooling water is removed by filtration and the pellets are dried in two centrifugal dryers. 

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