The applicability of the fluid bed incineration process for the disposal of petroleum refinery generated spent caustic and oily sludge in a commercial scale unit has been demonstrated. Operating problems have been studied. Design and operating procedural changes are suggested. The major process limitation stems from the loss of bed fluidity due to high particle size growth rate. Particle size growth rate is directly proportional to the particle diameter and rate of dissolved solid material charged and inversely proportional to the mass of material in the bed. The average particle diameter can be controlled by collecting and continuously returning fine material to the bed, utilizing an effective attriting system, and limiting superficial space velocity to avoid elutriation of fines. (Author Modified Abstract)