Drying residuals at ambient temperature with the Dry-Rex(TM) dryer - A patented process combined with a waste heat recovery system

The Dry-Rex(TM) dryer is a two-step, integrated, wet granulation-drying pro cess that uses a low-vacuum, forced-air stream at temperatures above 5 degr ees C as the main driving force. The process has been demonstrated in over 25 pulp and paper mills in North America on most types of residuals such as sludges (primary, biological and combinations, deinking), bark (alone or m ixed with wet biosolids) lime and wood chips, as well as fibrous products l ike bleached pulp, bagasse and peat. High-energy drying efficiencies (50 to 150 kWh/t of evaporated water) are achieved by combining the patented proc ess with a waste-heat recovery system. The heat recovery system captures ef ficiently and economically the excess thermal energy contained in existing waste streams (effluent, flue gases, building HVAC, etc.) and re-utilizes i t to pre-heat the fresh make-up air to the optimum drying condition. The Dr y-Rex(TM) dryer offers pulp and paper mills new opportunities to improve re siduals quality and dryness and reduce the environmental and economic impac t associated with their management. The process can also be designed to ope rate at higher than ambient temperatures with the addition of an external h eat source.