AbstractThis thesis examines the combustion of coal-oil slurries in the unusual low-recirculation conditions obtaining in the blast furnace tuyere raceway.
A computer-controlled combustion rig was built which would simulate, as nearly as possible, the conditions of air velocity (typically 200 m/s) air preheat temperature (typically 1000°c) and oxygen enrichment (up to 26% oxygen content by volume) obtaining on a modern blast furnace.
The results from this rig were used to calibrate a mathematical model of the mixing and combustion processes taking place. A theory of atomisation is proposed whereby the smaller coal particles are retained within the larger oil droplets, leaving the larger coal particles to combust separately. Using error analysis of the mathematical model, the size of coal particle which can remain within an oil droplet was found to have a ratio of less than 0.14.
The apparatus was not as accurate in the delivery of slurry as it was in the delivery of preheated, oxygenated air. The total accuracy was found to have a 95% probability of less than 10% error.
The mathematical model, however, was found to have a 95% probability of less than 5% error. When the work of other investigations - into the degree of recirculation obtaining in the tuyere raceway - is complete, the model will provide a satisfactory basis for prediction of maximum injection rates of coal-oil slurries into the tuyeres of a blast furnace, given the conditions of air blast obtaining.
|Date of Award||1983|