| 摘要 |
<p>In hot air drying chamber for food prods. a set of horizontal conveyor bands, spaced one above another, carry the prod. between a chamber feed port and a chamber discharge port. Within the chamber, hot air is blown into contact with the prod. The conveyor bands are permeable to the current of hot air. The side edges of the bands form a moving seal against the side walls of the chamber so that a recycled air flow can be blown through the bands but not around their side edges. The compartment between adjacent bands is made leak-proofat the ends of the bands. This is achieved by using band gullies with flat end faces and delivering from each band through a channel fitted with a rotary seal valve. Pref. freshly heated air is introduced, hot and dry, beneath the lowest of the conveyor bands and an equivalent vol. of cooler, moist air is extracted above the top band. The quantity of freshly heated air pref. represents less than 10% of the quantity of air recycled in closed circuit in a given period. The drying chamber is for drying food prods. e.g. fruits, vegetables, cereals, mushrooms, etc., esp. for drying plums to produce prunes. All the prod. is dried to the same extend so no sorting is required to eliminate inadequately dried prod. with air blowing through the conveyor bands, the prod. can be carried in thicker layers, so output is higher for a given dryer size. Air temp. drop is over a very low range, which improves prod. flavour.</p> |
