The tray resting on the lifting frame is charged with fresh product, lifted to the top position, and slid into the chamber by operating a hand mechanism. The lifting frame slides down again to the middle, ready to support the tray immediately above the intermediate heater. This tray is drawn out and moved down a little further. The product on the tray is riffled nd the tray pushed back into the chamber- this time below the heating surface. The lifting frame slides down to receive the lowermost tray of the second stack. It then moves a little way upwards and is slightly tilted so that the now dried product can be discharged. The emptied tray is moved to the bottom position and the new drying cycle commences See Fig 4.1) The drying progression, therefore starts at the top of the dryer where he higher temperature prevails, and finishes in thecool zone at the bottom, from where the tray with the dried product is drawn out and discharged. steam requirements are 600kg per hr at 7 bar for maximum throughput, th electrical load is 7KW for the heater fan and 0.7KW for the lifting device Double Through-Flow Dryer Thisis a demonstrably more sophisticated through-flow dryerdesigned by Mitchell Dryers Ltd, with twice the output of the single chamberdryer, and withless labourrequirement This is a semi continuous dryer, comprising two drying chamber each housing 10 perforated trays 3m by 2m by 150mm deep. The product filled trays travel automatically through the drying chambers at a rate commensurate with optimum drying and product quality(See TABLE 4.1) The primary drying chamber is designed for total rejection of the saturated air. The circulation fan is mounted directly above the heater batteries at the rear of the chamber and discharges the heated air into a bottom plenum hamber and the air is then directed vertically upwards through the stack of trays to the top and into the discharge hood to be ducted away to atmosphere The circulation fan in the primary unit handles 400cu m of air heated to 150C maximum. The heater has a maximum heat output of 2 350, 000 BTUs r hour when using steam at 2.72atm The second chamber air circulation is provided by a fan handling 270cu m of air. The trays are automatically advanced from the bottom to the top by four hydraulic lifting jacks, connected to the lifting frame. The trays are indexed to move into their drying position automatically At the bottom and top of the main framework there is a roller conveyor system upon which the loaded trays travel from the first chamber to the second (a)to enable an operator to examine the product at the intermediate stage of drying, and riffle over the product to effect a surface change before entering the cool chamber, and (b)on the bottom roller conveyor, to dischargeThe tray resting on the lifting frame is charged with fresh product, lifted to the top position, and slid into the chamber by operating a hand mechanism. The lifting frame slides down again to the middle, ready to support the tray immediately above the intermediate heater. This tray is drawn out and moved down a little further. The product on the tray is riffled and the tray pushed back into the chamber - this time below the heating surface. The lifting frame slides down to receive the lowermost tray of the second stack. It then moves a little way upwards and is slightly tilted so that the now dried product can be discharged. The emptied tray is moved to the bottom position and the new drying cycle commences See Fig 4.1). The drying progression, therefore starts at the top of the dryer where the higher temperature prevails, and finishes in the 'cool' zone at the bottom, from where the tray with the dried product is drawn out and discharged. Steam requirements are 600kg per hr at 7 bar for maximum throughput, the electrical load is 7KW for the heater fan and 0.7KW for the lifting device. Double Through-Flow Dryer Thisis a demonstrably more sophisticated through-flow dryer designed by Mitchell Dryers Ltd, with twice the output of the single chamber dryer, and with less labour requirement. This is a semi continuous dryer, comprising two drying chambers each housing 10 perforated trays 3m by 2m by 150mm deep. The product filled trays travel automatically through the drying chambers at a rate commensurate with optimum drying and product quality (See TABLE 4.1). The primary drying chamber is designed for total rejection of the saturated air. The circulation fan is mounted directly above the heater batteries at the rear of the chamber and discharges the heated air into a bottom plenum chamber and the air is then directed vertically upwards through the stack of trays to the top and into the discharge hood to be ducted away to atmosphere. The circulation fan in the primary unit handles 4OOcu m of air heated to 150°C maximum. The heater has a maximum heat output of 2,350,000 BTUs per hour when using steam at 2.72atm. The second chamber air circulation is provided by a fan handling 270cu m of air. The trays are automatically advanced from the bottom to the top by four hydraulic lifting jacks, connected to the lifting frame. The trays are indexed to move into their drying position automatically. At the bottom and top of the main framework there is a roller conveyor system upon which the loaded trays travel from the first chamber to the second (a) to enable an operator to examine the product at the intermediate stage of drying, and riffle over the product to effect a surface change before entering the cool chamber, and (b) on the bottom roller conveyor, to discharge 71