Patent ID: 7740751

Claim:
A hydrocarbon conversion process, comprising: a) passing a hydrocarbon stream comprising, in percent or parts by weight based on the total weight of hydrocarbons in the hydrocarbon stream: C 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, wherein the sulfur or sulfur containing compounds and the nitrogen or nitrogen containing compounds are measured as, respectively, elemental sulfur or nitrogen; through at least one heater comprising at least one burner for producing heat, a radiant section having at least one radiant section tube, and a convection section having at least one convection section tube in fluid communication with the at least one radiant section tube, wherein, (i) without first passing through the at least one convection section tube and before exiting the at least one heater, the hydrocarbon stream passes through the at least one radiant section tube before the hydrocarbon stream enters and passes through the at least one convection section tube so that (ii) the temperature of the hydrocarbon stream entering the at least one convection section tube is substantially similar to the temperature of the hydrocarbon stream exiting the at least one radiant section tube, and (iii) the at least one convection section tube receives from about 10% to about 45% of the heat produced by the at least one burner.