One exemplary embodiment of the present invention can be a hydrocarbon conversion process. The process may include passing a hydrocarbon stream through at least one heater including at least one burner, a radiant section, and a convection section. Generally, the stream passes through the radiant section and then through the convection section before exiting the heater. Desirably, the hydrocarbon stream includes, in percent or parts by weight based on the total weight of hydrocarbons in the stream: C.sub.4 or less: less than about 0.5%, sulfur or sulfur containing compounds: less than about 1 ppm, and nitrogen or nitrogen containing compounds: less than about 1 ppm. Preferably, the sulfur or sulfur containing compounds and the nitrogen or nitrogen containing compounds are measured as, respectively, elemental sulfur or nitrogen.