‘Sounds’ Like The Perfect Spray Dryer
OK because I am Irish I am an ardent tea drinker, not that I do not like coffee. Did you know that spray dried coffee was invented in 1901, in Chicago by a Japanese scientist called Satori Kato? Since then spray drying of a wide range of ingredients has now become possible with advances in spray dryer design and operation. Today spray dryers in various design formats are used to dry such materials as milk powder, spices, flavourings, pigments, ceramic materials, enzymes and catalyst supports.
Spray drying involves evaporation of the moisture from the atomised liquid or slurry by spraying this material into a drying medium, usually hot air. There are three basic techniques employed for such rapid drying.
Co-Current – in which the material is sprayed in the same direction as the flow of hot air through the vertical vessel.
Counter-Current – in which the material is sprayed in the opposite direction as the hot air flow. The hot air flows upwards and the product falls through increasingly hot air to the base of the vessel.
Combined Current – in which the advantages of both types of drying are combined. The product is sprayed upwards and only remains in the hot zone for a short time to remove the residual moisture. Gravity then allows the product to fall into the cooler zone.
In all cases the exiting dry materials (which in some cases can have an extremely small particle size) exit the cone base of the dryer and are then passed into either a cyclone or bag filter to separate the material from the air stream.
However these spray drying systems are not without their problems which mainly centre around:-
Spray drying involves evaporation of the moisture from the atomised liquid or slurry by spraying this material into a drying medium, usually hot air. There are three basic techniques employed for such rapid drying.
Co-Current – in which the material is sprayed in the same direction as the flow of hot air through the vertical vessel.
Counter-Current – in which the material is sprayed in the opposite direction as the hot air flow. The hot air flows upwards and the product falls through increasingly hot air to the base of the vessel.
Combined Current – in which the advantages of both types of drying are combined. The product is sprayed upwards and only remains in the hot zone for a short time to remove the residual moisture. Gravity then allows the product to fall into the cooler zone.
In all cases the exiting dry materials (which in some cases can have an extremely small particle size) exit the cone base of the dryer and are then passed into either a cyclone or bag filter to separate the material from the air stream.
However these spray drying systems are not without their problems which mainly centre around:-
- Material building up on the vertical side walls of the dryer, then falling off in lumps, so blocking the outlet
- Material building up and blocking over the base outlet
- Fine particles blocking the filter bags and also the filter discharge hopper. These serious problems which used to cause major and costly down time can easily and economically be eliminated with the installation of suitable models of Primasonics Acoustic Cleaners.
Should you wish to enquire about a particular spray dryer application just click on the following link and complete our Spray Dryer Questionnaire
Photo left:
Acoustic cleaner installed to prevent spray dryer material build-up.
Labels: material build up, spray dryers
posted by Don Cameron at
9:13 AM
