Reception hoppers

The cattle manure with about 25 p.c. dry matter content and the litter is transported by trailer to the reception hopper for manure and solid organic wastes. From here manure will be delivered by a bucket elevator, with the help of feed screw conveyor into the digester tower made of anticorrosive steel. The slurry and the sewage water mixed with faeces will be pumped into the digester. 

The reception hopper into which road and rail waggons deliver should be sited under cover (e.g. within a structure with three walls, a roof and a curtain on the open side to assist in containing dust during discharge). It should be constructed from mild steel or concrete and, for safety reasons, should be covered with a grid. Its capacity should be at least equal to that of the largest delivery vehicle. 

The discharge mechanism from the hopper should be fast enough to ensure that the hopper can be emptied before the next delivery. Where the lime is to be reduced in size, a crusher should be installed immediately after the reception hopper so that subsequent handling equipment can be kept as small as possible. A tramp-metal detector should be fitted before the crusher to prevent damage. 

Where the consumption of lime is insufficient to justify reception hoppers and storage bunkers, the product should be stored on a concrete base, preferably in a separate bay within a building to prevent excessive air slaking. 

Pneumatic conveying is frequently a cost effective option, using a Rootes-type blower and a rotary blowing seal. Alternative proprietary units are available. Pipelines should normally have a nominal bore of at least 50 mm and bends should have a radius of at least 1 m. The reception hopper should be fitted with an air-pressure relief valve. Powder pumps are also used successfully. They tend to use less air than pneumatic conveying systems. 

Numerous devices have been developed to feed materials into pipelines, as well as to disengage materials from the conveying air at the reception point. In vacuum systems the material feed is invariably at atmospheric pressure and so the pipeline can either be fed directly from a supply hopper or by means of suction nozzles from a storage vessel or stockpile. Pressure capability, control and air leakage are important points to consider... 

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