Application: Test work to obtain operational conditions and basis for design of industrial size closed-cycle spray dryers.
Capacity: The evaporative capacity depends on the solvent in question, but with water as the medium it is 10-60 kg/h and the minimum feed requirement is about 200 kg.
Specification: The chamber has a 2.5 m diameter, a 2.5 m cylindrical height and a 60 degree conical bottom. The 1250 kg/h of drying gas (nitrogen with a low oxygen content) is heated by an electrical heater and has a maximum inlet temperature of 300 °C.
The feed is supplied by a Mono pump or a piston pump and atomized by one of the following:
- rotary atomizer (type FX1)
- co-current pressure nozle
- counter-current (fountain) pressure nozzle
- two-fluid nozzle.
Product is recovered by one-point or two-point collection from the chamber, cyclone and/or bag filter – after which the drying gas goes to a scrubber-condenser tray column and is returned to the heater.
The plant is equipped with Hepa filters as well as carbon filter for cleaning of exhaust gasses before emitting the surplus drying gas to the surroundings.
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General
GEA Niro has played a significant part in the application of closed-cycle spray dryers in hard metal powder manufacture and, today, the majority of the world’s cemented carbides are processed resulting from this development. For both traditional and advanced high-tech ceramics, GEA Niro has supplied a number of spray dryers in open and closed cycle concept.
All closed-cycle spray dryers for production of carbides (hard metal powders) are pre-erected and pressure tested before shipment.