A PYROLYSIS FURNACE WITH REACTOR TUBES OF ELLIPTIC CROSS-SECTION

Circular tubes suspended in pyrolysis furnaces suffer from significant nonuniformities in heat flux, tube skin temperature, and coking rate profiles around the tube perimeter, due to the presence of ''front'' s ides and ''shadow'' sides on the tubes. Simulation results for an etha ne cracker with cracking tubes of elliptical cross section reveal that smoother circumferential heat flux, tube skin temperature, and coking rate profiles are obtained as the eccentricity of the elliptical tube s increases. The circumferential maximal values in coking rates are re duced by 30%. The more uniform tube skin temperature distributions and coke layers in tubes of elliptical cross section favor the run length of the furnace and the tube metal life.