Patent ID: 7168374
Filing Date: 2007-01-30
Classification: F23C,F23D

Abstract:
1. A method for operating a solid fuel burner comprising a fuel nozzle for ejecting a mixed fluid of a solid fuel and a transporting gas having an oxygen concentration lower than an oxygen concentration of air, an outside air nozzle for ejecting air, said outside air nozzle being arranged outside said fuel nozzle, an additional air nozzle for ejecting air into the mixed fluid inside said fuel nozzle, and a flow passage contracting member placed in said fuel nozzle, said flow passage contracting member having a first portion that forms a flow-passage cross-sectional area that decreases in a direction of gas flow and a second portion that forms a cross-sectional area that increases in the direction of gas flow, said first portion being upstream of said second portion, relative to the direction of gas flow, wherein said additional air nozzle is provided at a portion of said flow passage that has a constant cross-sectional area downstream of said second portion of said flow passage contracting member, and an inner peripheral wall of an outer side partition wall of said fuel nozzle is constant in cross-sectional area of flow passage defined thereby, from an installation position of said additional air nozzle to an outlet of said fuel nozzle, said method comprising: making both fuel concentration and oxygen concentration in a cross-sectional area at an exit of said fuel nozzle higher on the inner peripheral wall side of said fuel nozzle than fuel and oxygen concentrations in a central portion.