A method of combustion of sludge,and a furnace for use in the method

摘要

1,080,318. Sludge consuming furnaces. VON ROLL A.G. Nov. 11, 1964 [Nov. 11, 1963], No. 46056/64. Heading F4B. A furnace for oombusting partially dewatered sewage sludge comprises a predrying compartment 3, separated by a wall 4 from a following combustion compartment 5 incorporating a drying zone 14, a primary combustion zone 15 and a burn out zone 16, and a conduit 10 to lead vapours from the predrying compartment 3 to mingle with combustion gases passing from the combustion compartment 5. A layer 8 of pressed sludge from shoot 2 is predried in compartment 3 by recycling flue gases at 250-300‹ C. from rear flue 11a through conduit 9, controlled by valve 9a, to the inclined bar grate 7. The vapours at 100‹ C. so evolved pass via line 10 to flue 11 to mingle with combustion products at 750-800‹ C. for deodorization. The fuel bed 8a passes under common wall 4 and layer thickness regulating slide 6 to combustion compartment 5 on grate 13. In drying zone 14 where the grate is protected by a cold air supply, the remaining vapours evolved by radiant heat from baffle wall 12, keep wall 4 cool. In primary combustion zone 15 and burn-out zone 16 the volatile and fixed combustible components respectively are burnt by a primary undergrate air supply at 250-300‹ C., through conduits 17 and 18, controlled by valves 17a1, 18a1. Both of these zones may be constituted by two subzones. A supplementary fuel burner 19 and secondary air ducts are provided. The combustion products are utilized in waste heat boiler 60. In a modification (Fig. 2) the prodrying compartment is heated by an air blast at 250-300‹ C., the resultant air/vapour mixture at 100‹ C. being used to provide part of the primary combustion air for zone 15.