GB1475036A - Disposal of wet waste material by combustion in a fluidized bed - Google Patents

Abstract

1475036 Incinerators; consuming smoke A AHLSTROM OSAKEYHTIO 5 Feb 1975 4814/75 Heading F4B In a fluidized bed incinerator 1 for burning sewage sludge and comprising a combustion chamber 2, a predrying chamber 8 utilizing a portion of the waste gases from said combustion chamber 2 for drying the incoming wet sludge, and an afterburner 23, waste gases leaving the top of the predrying chamber 8 are admixed with waste gases leaving the afterburner 23 in a mixing chamber 18. The predrying chamber, which is fed with wet sludge through a feeder 7, includes a pair of vertical shafts 10 and 11 rotated in opposite directions by means of gearing 12 and an adjustable speed motor 13. The shafts are provided with inclined blades 14 which, when rotated, act as conveyors to advance the wet sludge downwardly towards the opening 9 in the top of the chamber 2 while disintegrating the sludge and mixing it with the gases from the combustion chamber 2. Relatively cool waste gases discharged from the top of the predrying chamber are fed to the mixing chamber 18 and/or to the inlet of the afterburner 23 via a fan 16 and ducts 17, 34. Hot gases from an auxiliary oil burner 19 can be selectively delivered to the mixing chamber 18, the inlet end of the afterburner, combustion chamber 2 and windbox 3 via ducts 22, 24, 25 and 33 respectively. Combustion air, preheated in a heat exchanger 31 downstream of the mixing chamber 18, can be supplied to the windbox 3 via duct 6, to the auxiliary burner 19 via duct 20, and to the afterburner 23 via duct 26 and branches 27, 28 and 29 having radial or tangential nozzles 30. The temperature of the fluidized bed 5 can be controlled by means of fuel oil supplied through a duct 32.