PURPOSE: To enable burning gaseous fuel in a manner of multifuel combustion in safety, without raising environmental problems, and highly efficiently in a circulating, fluidized bed type combustion chamber with a two-stage supply of air by a method wherein gaseous fuel is fed through a pipe provided inside a secondary air-feeding pipe and a specific relationship is maintained between the amount of secondary air fed through a lower-level inlet and the flow-rate of gaseous fuel.
CONSTITUTION: Granular coal 1 and limestone 3 are fed into a fluidized bed combustion chamber 6 by a feed pipe 5 and primary air blown into the fluidized bed combustion chamber 6 by a primary air-feeding pipe 8, which is connected to the bottom of the fluidized bed combustion chamber 6, keeps the granular coal 1, limestone 3, etc., in a fluidized state. A secondary air upper-level feed pipe 9 and a secondary air lower-level feed pipe 24 are connected to the fluidized bed combustion chamber 6 and a gaseous fuel feed pipe 25 is connected to the fluidized bed combustion chamber 6 in a concentric arrangement inside the secondary air lower-level feed pipe 24. Under this piping arrangement the feeding of air and gaseous fuel is made to maintain a relationship between Q1 representing the amount of secondary air at the lower level, i.e., the stream through the secondary air lowerlevel feed pipe 24, and Q2 representing the flow-rate of the gaseous fuel, i.e., the stream through the gaseous fuel feed pipe 25, expressed as Q1/Q2≥0.3A0 where A0 represents a threoretical amount of air for combustion against gaseous fuel.
HARAJIRI HACHIRO
KAMIYA JUNICHI
FURUTA MASAKAZU
HIURA FUMIAKI
TANAKA YUKIMASA
NITTETSU PLANT DESIGNING CORP