Residue vitrification plant with regenerative heat recovery system

摘要

The parent patent (P4435166.6) describes a plant for vitrifying residues (e.g. clarification sludge, contaminated muds or soils, slags and filter dusts, esp. from waste incineration plants), consisting of a residue prepn. unit, a blending unit for mixing and dosing the prepd. residues and glass-former, a glass melting unit with a system for regenerative heat recovery from the flue gases, and a cleaning unit for the flue gases. A device (esp. a rotary hearth furnace), heated by fossil and/or other fuels and supplied with preheated combustion air, is provided between the blending unit and the glass melting unit for drying, degassing, oxidising and sintering the dosed batch. First regenerators are provided for preheating the combustion air in counter-current to off-gas from the glass melting unit at an off-gas temp. maintained such that condensate formation is avoided. The regenerators are followed by a recuperator, through which the off-gas flows and in which the condensate is sepd. and supplied to the prepn. unit, the combustion air being preheated in the recuperator for the rotary hearth furnace. The novelty is that (a) the furnace off-gas is supplied to a fossil fuel-fired off-gas post-combustion stage having an outlet connected to second regenerators; (b) the off-gas from these regenerators is combined with off-gas from the first regenerators and fed into the recuperator; and (c) the combustion air, preheated in the recuperator, for the post-combustion stage is fed in counter-current to the off-gas through the second regenerators, in the same manner as the combustion air for the rotary hearth furnace, at an off-gas temp. maintained to avoid condensate formation.