External preheating of fresh air in solid material furnaces

Abstract

The invention relates to a method for utilizing the heat in the lower temperature range of up to 1000° C., preferably up to 500° C., for preheating fresh air which is added to a solid material furnace, preferably designed as a grate furnace with sub-stoichiometric combustion and supply of fresh air in several stages, or to a circulating fluidized-bed furnace.

1 . A method of using heat in the low-temperature range below 1000° C. to preheat fresh air that is fed to a solid-material firing system, implemented as a grate firing system with substoichiometric combustion and the addition of fresh air in multiple stages, or that is added to a circulating fluidized-bed combustion system. 
     
     
         2 . The method according to  claim 1 , wherein the heat introduced into the combustion process is used together with fuel-based energy to superheat steam of a third process or of the same process of the waste heat source. 
     
     
         3 . The method according to  claim 1  wherein biomass, industrial or municipal waste, coal, or mixtures of the above-mentioned materials are combusted. 
     
     
         4 . The method according to  claim 1  wherein fresh air preheated in a maximum of five stages is added to the grate firing system. 
     
     
         5 . The method according to  claim 1  wherein geothermal heat, solar-thermal heat, heat from refuse incineration, nuclear energy, or waste-heat energy from exothermic processes is used to preheat the fresh air. 
     
     
         6 . The method according to  claim 1  wherein the air is preheated to 350° C.-1000° C. 
     
     
         7 . The method according to  claim 1  wherein thermal oil or molten salt is used as the heat transfer system to effect subsequent fresh-air preheating.