Closed circuit heating of roasting furnace which uses hot gases - involves use of heat exchanger with double circuit

摘要

Roasting machine is described in which a hot gas is used to process the contents of the machine and in which the off gases are processed in an after-burner. The heat content of the off-gases leaving the after burner are utilised to preheat the incoming gas to the roasting machine. The after-burner has a main chamber from which hot gases are directed to one circuit of a heat exchanger from which they exit as cold off-gas for discharge into the atmosphere. The heat content passes to a second circuit in the heat exchanger from which heated fresh gas is withdrawn and used to process the contents of the roasting machine. The system avoids recycling the harmful or odorous constituents of the gas.