Airless Drying

Re-circulates the heated dryer atmosphere which eliminates energy losses to the flue whilst generating a high humidity atmosphere allowing raised heating cycles.

Introduction

Energy efficiency in process operations is increasingly important to manufacturers in terms of both their competitiveness and their environmental conservation commitments. Substantial benefits can be obtained in ceramic processing if a conventional dryer is replaced by an airless dryer.

The energy demands of a conventional dryer are a result of the energy required to evaporate the moisture from the product and the heating of the air flowing through the dryer and eventually to atmosphere.

Principle

Airless drying re-circulates the heated dryer atmosphere which eliminates energy losses to the flue whilst generating a high humidity atmosphere which allows raised heating cycles without causing damage to the product.

Benefits

Compared with a conventional dryer, airless dryers can provide numerous advantages. The extent of these will vary with individual types of application and installation; however, the following are typical of the potential benefits which may be taken into consideration when specifying a dryer.

Manufacturing flexibility: The speed of drying makes it possible to adopt more flexible manufacturing systems in addition to using the airless dryer as a more economic direct replacement for conventional dryers. This flexibility enables small batches to be produced, allowing the manufacturer to satisfy customer requirements, for example, special products with short delivery lead times.

Reduction of the effective gas cost for drying: Savings of up to 95% have been recorded in trials to date, with an airless dryer consuming 6 therms/tonne of dried product instead of the previous requirement of 80 therms/tonne. In this case, the heat was first used for drying and then used to produce around 4 tonnes of boiling water per tonne of moisture removed from slurry with a moisture content of around 50%.

Recovery of evaporated moisture in the form of distilled water: This may assist in the production of purer products if used for final rinsing, etc.

Approximately halving drying times: This speeds up product time to delivery, reducing working capital and freeing floor space which would otherwise be required for dryers.

Improved product quality: For certain products dried in an airless dryer, removal from the trays and subsequent pulverisation may be easier.

Reduced space requirements: As airless dryers are smaller than conventional dryers, they occupy less space in the factory.

Enhanced manufacturing versatility: The speed of drying offers increased flexibility in production programmes as smaller batch sizes become more economically effective.

We welcome the opportunity to discuss the application of the airless dryer concept in any industrial environment.