Relationships Between Air Ratio and Furnace Performance in M. H. F.

Abstract

The thermal processing has become one of indispensable processes of sewage sludge treatment in Japan. However, it is the most energy consuming process of sewage sludge treatment processes. Therefore, energy saving is now the most important subject in this field.
As the equipment of sludge thermal processing, Multiple Hearth Furnace (M.H.F.) is mostly used in Japan. M.H.F. has hitherto been operated at high air ratio of 2.0-3.0. The main operating factor which influences energy consumption of M.H.F, is air ratio for combustibles. So, low air ratio operation is the most effective method for energy saving of M.H.F. Low air ratio operation is defined as the operation at lower air ratio of 1.2-1.5. Due to reduction of waste gas volume followed by reduction of sensible heat carried from M.H.F., auxiliary fuel for the furnace is reduced.
A study on relationships between air ratio and furnace performance in M. H. F Was conducted. Material balance model of M.H.F.with some assumptions was chosen and the above relationships was simulated.
This simulation verified how furnace performance is influenced by air ratio.