Abstract
The present paper examines the air distribution mode for a novel arch called the double herringbone arch to improve the thermal efficiency of travelling grate boilers. The influences of the three air distribution modes on coal bed combustion are first studied by measuring the gas species distributions along the grate length above the coal bed. The test result is inputted as the boundary condition of the numerical simulation, which compares the gas combustion features in the furnace of a common arch boiler with those of a double herringbone arch boiler under different air distribution modes. The results show that the cooperation of the rear enhanced air distribution mode and the double herringbone arch not only promotes the burnout of the coal bed but also reduces the combustible gas loss. Finally, industrial retrofit indicates that the thermal efficiency of a common arch boiler can be improved by about 5–10% using a double herringbone arch with the aid of the rear enhanced air distribution mode.