OPERATION OF A FLUID BED DRYER

SYSTEM CONTROL

1.1 Fluid bed Dryers are quite hazardous from explosion point of view. Drying of hybrid mixtures in the equipment makes it more hazardous. Such dryers must therefore be properly designed and suitably located as to facilitate free venting from explosion relief zone in event of a dangerous situation.

1.2 High air velocities for fluidization, attribute to high electro-static changes on the material being dried and dryer bags. The dryer must therefore be adequately earthed. Synthetic cloth have capacity to accumulate electro-static charges to a dangerous level. Proper risk assessment has to be made, if such cloth are to be used as an exception.

1.3 Every fluid bed dryer must have an explosion relief device of the required size.

1.4 In case of hybrid mixture, concentration of the vapours in the air must not exceed 25% of L.E.L (Lower Explosion Limit), of the solvent at any givven time during drying operation. Drying characterists must be duly monitored periodically with respect to concentration of vapour in Initially, cold air must be blown for atleast 15 minutes before switching on to heating.

1.5 Electrically heating must not be allowed in fluid bed dryer.

1.6 All the electrical fittings in the room must conform to ISI specifications of Flameproof Electrical fittings.

1.7 Fluid Bed Dryers produce high noise levels. Necessary engineering controls are required to be exercised.