GB756744A - Continuous process for drying, preheating, and devolatilization of carbonaceous materials - Google Patents

Abstract

756,744. Distilling solid carbonaceous materials. SILVER ENGINEERING WORKS, Inc. Aug. 4,1953[auk. 12, 1952], No. 21513/53. Class 55( 1 ). In a process of distilling low rank carbonaceous fuels the dried finely divided fuel is passed in a hot carrier gas containing free oxygen upwardly through a zone where gases, tars and light oils are distilled from the fuel, the residence time of the fuel in the distillation zone being limited so that it is subjected to partial but incomplete combustion. In Fig. 2 crushed low rank fuel, e.g. lignite containing about 30 per cent moisture, is fed by a conveyer 15 from a hopper 12 to a drier 16 where it is entrained in hot gases from a combustion chamber 17. The mixture passes into a separator 40 and the separated dried fuel collects in a hopper 25 and a bin 41 before passing by line 46 and feeders 47 and 50 into line 49 for transfer by preheated air from line 52 to the carbonization zone 53, Fig. 3. The gases from separator 40 pass off by line 42 and are in part recirculated through the drier by lines 31 and 34 and ports 36 and 37 or treated in further separators 44 for removal of fines. The separated fines collect in a hopper 24 and are passed with further fuel fed from hopper 25 by line 51 to a burner 22 and combustion chamber 17 for producing hot gases for the drier 16. Air for the burner 22 is fed by fan 20 into an annular jacket 21 surrounding the combustion chamber 17. Fuel for starting the process may be supplied to the burner 22 by line 30. The carbonization zone 53 is heated externally by combustion gases from a burner 63 to which coal gas is supplied by header 64 and a mixture of air (from line 56) and recirculated flue gases (from line 57) via line 59, preheater 60, chamber 61 and line 62. Flue gases from the burner 63 not recirculated pass out through preheater 60, a preheater 67 and then either to stack by line 74 or by line 88 to a scrubber 89 to supply cleaned flue gases for transporting char from a feeder 85. Preheater 67 preheats air admitted through fan 69 and line 68 for supply to line 52. Dried fuel from line 49 and preheated air from line 52 pass with coal gas supplied from header 64 by line 7 la into the carbonization zone where the fuel is distilled at about 900‹F., the residence time in the zone being about 10-15 minutes. Char, distillation gases, tar and light oils pass by line 77 to insulated separators 82, the char falling by line 80 to feeder 85 and thence by line 87 to a boiler and the gases, tars and light oils leave by line 84 for further treatment. In a modified form of the apparatus the carbonization zone comprises a double-walled vessel the bottom of the inner shell being provided with a grid through which the line feeding dried fuel from the drier extends. In operation the outer shell of the carbonization zone is externally heated by combustion gases and combustion gases are circulated downwardly between the two shells of the zone and pass upwardly through the grid into the carbonization zone.