Sludge drying system with recycling exhaust air

A sludge drying system for drying wet sludge to produce pellets of a predetermined size, comprising:

• a furnace having an exhaust air chamber, a first inlet for providing recycled exhaust air into said exhaust air chamber, a first outlet for discharging hot exhaust air from said exhaust air chamber as system air to dry the sludge, and a first passageway extending between said inlet and said outlet for passing the recycled exhaust air through said exhaust air chamber;
• a burner coupled to said furnace for producing a flame within said furnace to heat the recycled exhaust air;
• a deodorizing chamber for deodorizing off-gases to be discharged to the environment, and having a second inlet for providing the off-gases into said deodorizing chamber, a second outlet for discharging the off-gases from said deodorizing chamber to the environment, and a second passageway extending between said second inlet of said deodorizing chamber and said second outlet of said deodorizing chamber for maintaining the off-gases passing through said deodorizing chamber for a predetermined period of time, said second passageway being separate from said first passageway to maintain the off-gases to be discharged separate from the exhaust air to be recycled as system air, and said deodorizing chamber being coupled to said furnace adjacent the flame produced by said burner to heat the off-gases passing through said deodorizing chamber;
• a dryer fluidly coupled to said furnace's outlet for receiving the system air from said furnace, said drying including means for receiving the system air and wet sludge therein and means for discharging the system air and sludge pellets produced by said dryer from the wet sludge;
• separating means, fluidly coupled to said dryer, for separating the system air from the sludge pellets;
• and
• dividing means, fluidly coupled to said separating means to receive the system air, for dividing the system air into two streams with one stream being fluidly coupled to said first inlet of said furnace and the other stream being fluidly coupled to said second inlet of said deodorizing chamber.