The tuyere combustion zone has been studied on an experimental furnace by measuring dimensions and temperature in the raceway.
The effects of variables such as the blast velocity, tuyere diameter, and coke size are studied. Expressions are derived for estimating the length, width, and height of the raceway in terms of the velocity and density of the blast air, tuyere diameter, and coke properties such as the size, density, and shape factor.
Discussion is carried out according to the idea that the compressive force of blast to the coke bed is balanced with tendency of collapse of the raceway wall, and that coke in the raceway is fluidized by raceway gas.
Measurements of operating blast furnaces by rod test are shown to be generally in good agreement with those on the experimental furnace.