Prevention of dust emissions from drying

Dryers usually have very high airflowrates (typically some 10000 m /tonne of PVC) with a low 

Due to the difference in particle size between emulsion and suspension PVC, the dried resin is separated from the air by multiple bag filters in the case of emulsion PVC or by cyclones in the 

Bag filters are most efficient in powder removal, but bags can split from time to time, thus it is important that the exit air is monitored for dust content either continuously or effectively in order to ensure that such split bags can be detected and replaced immediately. Another method for efficient final powder removal is water scrabbing. 

The stripped suspension is normally dewatered as much as possible by mechanical processes (e g. centrifugation) in order to reduce the consumption of energy used for drying. Effective drying is then ensured by one of several drying steps in equipment of miscellaneous designs, but all with the aim of optimising the combination of temperature, airflow and residence time. 

The spraying nozzles can be blocked if coarse PVC particles are present in the latex, and thus latex is often filtered prior to drying to optimise dryer throughput. 

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