running sludge drying unit

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We strongly recommend consideration be given to running a drying unit in continuous mode, at least over a 5- day period. In the case of drying units with a high evaporation capacity (above 3 t · h–1), operating the unit continuously at the rate of 7,500 h·annum–1 effective running time would be regarded as reasonable. Depending upon the plant's operating routine (shifts, on-call night duty, presence of personnel at the weekend, etc.) the length of time of operation may be lowered.

Drying unit operation organisation will vary considerably depending on whether or not the unit has been designed with a pelletisation unit. Without post-pelletising units, it is often accepted that this drying unit can be automated to the point where it no longer has to be manned continuously, particularly during night shifts. In this case, an efficient call-out system needs to be set up. This type of system works well in Naratherm and Innodry installations.

With a post-pelletisation unit, this principle only applies when the pelletisation unit capacity is over-designed so that it can only be operated under supervision (e.g. day shift). In this case, the drying unit must include a buffe storage system between the dried products outlet and the post-pelletisation unit intake.

When the post-pelletisation unit is directly in line with the dryer and even if the pelletisation unit capacity is backed up 100%, we do not recommend running this system without permanent manning. The same applies to intensive recirculation units.