Abstract: This paperanalyzed the causesfor the biomass leakage in the second section of preheating pipeline in convection section of pyrolysis furnace instandby process. It highlighted the corrosion mechanism of the feed elbow in the second section outlet pipeline of preheating convection section of pyrolysis furnace under the conditions of operation, coke burning and standby. The process operation scheme was optimized. The paper also proposed the measures for continuous feeding of dilution steam into the outlet pipeline of the second section of feeding preheating when the pyrolysis furnace is in the states of standby and coke burning.

Key words: pyrolysis furnace; convection section; feed elbow; corrosion; mechanism; dilution steam; standby and coke-burning