Biomass-mixed, pulverized coal-fired burner and fuel combustion method

A biomass-mixed, pulverized coal-fired burner, comprising:

• a biomass fuel jet nozzle having a biomass fuel jet port that jets biomass fuel conveyed by biomass fuel primary air as a biomass fuel stream;
• a pulverized coal fuel jet nozzle having a pulverized coal fuel jet port that surrounds an opening in the biomass fuel jet port, the pulverized coal fuel jet nozzle jetting pulverized coal fuel conveyed by pulverized coal fuel primary air as a pulverized coal fuel stream;
• a secondary air nozzle having a secondary air jet port that surrounds an opening in the pulverized coal fuel jet port, the secondary air jet port jetting secondary air;
• and
• a tertiary air nozzle having a tertiary air jet port that surrounds the secondary air jet port, the tertiary air jet port jetting a tertiary air swirl flow, wherein
• the biomass fuel jet nozzle includes a biomass fuel conveying pipe that forms a flow path for the biomass fuel stream, and includes a biomass fuel swirl vane that converts the biomass fuel stream to a swirl flow whirling around an axis of the biomass fuel conveying pipe to thereby make a fuel concentration lower on an axis side of the biomass fuel conveying pipe and higher on an outer circumferential wall side of the biomass fuel conveying pipe,
• the biomass fuel jet port has a pipe end extending in parallel with a pipe axis,
• the biomass fuel jet nozzle further includes a biomass fuel baffle plate disposed on a pipe inner wall upstream of the pipe end, the biomass fuel baffle plate reducing a swirl of the biomass fuel stream jetted from the biomass fuel jet port,
• the pulverized coal fuel jet nozzle includes a pulverized coal fuel conveying pipe that forms a flow path for the pulverized coal fuel stream, a pulverized coal fuel swirl vane that converts the pulverized coal fuel stream to a swirl flow whirling around an outer circumference of the biomass fuel jet nozzle to thereby make a fuel concentration higher on an outer circumferential wall side of the pulverized coal fuel conveying pipe, a flame stabilizer disposed at a pipe end of the pulverized coal fuel jet port and having a funnel-shaped widening ring including an inner face having an inner diameter larger than an inner diameter of the pulverized coal fuel convening pipe and a stepped part formed at the inner face of the widening ring and continuously extending around the entire circumference of the pulverized coal fuel jet port, and a pulverized coal fuel baffle plate disposed on a pipe inner wall upstream of the flame stabilizer, the pulverized coal fuel baffle plate reducing a swirl of the pulverized coal fuel stream jetted from the pulverized coal fuel jet port,
• a spread angle of the pulverized coal fuel stream jetted from the pulverized coal fuel jet port is reduced by the flame stabilizer having the stepped part and the pulverized coal fuel baffle plate,
• the stepped part includes a lateral face having an inner diameter larger than an inner diameter of the pulverized coal fuel conveying pipe,
• the secondary air jetted from the secondary air jet port forms a buffer stream between the pulverized coal fuel stream and the tertiary air swirl flow, and
• the pulverized coal fuel stream is formed such that the biomass fuel stream jetted from the biomass fuel jet port is enveloped by the pulverized coal fuel stream jetted from the pulverized coal fuel jet port.