Study On Atmospheric Residue Catalytic Pyrolysis Process For Maximizing Yields Of Propylene And Ethylene(MPE)

Propylene and ethylene are the major raw chemical materials for organic chemical industry, which are mainly derived from hydrocarbon steam cracking process. Along with the rapid development of world economy, propylene and ethylene's market demands are increasing significantly. In view of steam cracking process with the characteristics of high energy consumption, low propylene/ethylene ratio, lack of feedstock, study on the heavy oil catalytic pyrolysis to maximize yields of propene and ethene is of far importance.The atmospheric residue with high content of hydrogen and saturates is very good potential resource for FCC producing light olefins. So, this paper chooses Daqing atmospheric residue as raw material to explore the optimum operation conditions for maximizing yields of propylene and ethylene, and the effects of different factors on the reaction progress and product quality are also analyzed. On the basis of systemic case study, the author suggest that catalytic pyrolysis process needs higher reaction severity than conventional FCC unit to achieve the goal of higher propylene and ethylene yields, and controlling the forming of low-value product simultaneously, such as appropriate reaction temperature and residence time, large catalyst/oil ratio.C4 and light FCC naphtha (LN) distillate are both light feedstocks with high olefin content, as a result they can be availably used for manufacturing light olefins. This paper definitudes operation conditions impacting olefin yield through detailed investigation, and gets optimized conditions for C4 and LN, that is, high reaction temperature, appropriate residence time, large catalyst/oil ratio.With the purpose of maximizing the yields of propylene and ethylene, this paper adopts a proper feeding method-combinatorial injection(stratified injection), which includes stratified injection/stratified control, light component recycling, light hydrocarbon over-cracking to generate light olefin, large catalyst/oil operation, and so gets high propylene and ethylene yields and good product distribution. In experiment study, C4, LN, atmospheric residue, these three feeds are stratified injected into the riser and successively contact with catalyst to bring about the cracking reaction. The amount of C4 and LN feed is determined according to the generation from atmospheric. Under two operation pressures, the yields of propylene and ethylene are both higher, which are 48.16wt%(atmospheric pressure) and 41.87wt%(0.25 Mpa).