The well-known steam cracking is the major olefin production process worldwide. Light feedstock supply deficient and propylene/ethylene ratio imbalance impels the development of catalytic cracking processes to join the olefin production ranks. Catalytic cracking route based on different reaction mechanism is expected to raise the propylene/ethylene ratio. DCC is a commercialized technology using heavy hydrocarbons through mainly catalytic reaction differed from the solely thermal reaction in steam cracking. Its product propylene/ethylene ratio is 3.6 at a propylene yield of 24.8m% using an atmospheric residue under a reaction temperature of 829K. A new technology named CPP modified from DCC takes the advantages of both thermal and catalytic reactions for maximizing both ethylene and propylene production. A commercial trial with a throughput of 80kt/a showed that a propylene/ethylene ratio of 0.9 at an ethylene yield of 20.4m% under a cracking temperature of 913K with an atmospheric residue feedstock. Its propylene/ethylene ratio is adjustable in the range of 0.6–0.9, which is higher than that of steam cracking. CPP technology can be heat balance operated in a fluidized reaction/regeneration system.
The traditional steam cracking possesses the features of using light hydrocarbon feedstock, yielding a propylene/ethylene ratio of 0.5 and through solely thermal reaction. The increasing demand of virgin naphtha as feedstock will cause an unavoidable imbalance in supply from crude oil. Although ethane is attractive for its high ethylene yield in natural gas enriched countries, but its propylene/ ethylene ratio is less than 0.1. Since the world demand for propylene is expected to increase in the coming 20 years and the expected annual growth percentage of propylene is even higher than that of ethylene, so attention is paid to regulating propylene/ethylene ratio for keeping the propylene/ ethylene balance in olefin production. Olefin production from heavy hydrocarbons is also be concerned.
The expected world ethylene and propylene capacity and demand, feedstock options for steam cracking and their propylene/ethylene ratios are deliberated. Alternative cracking technologies using heavy hydrocarbons, especially newly developed catalytic cracking processes, DCC (Deep Catalytic Cracking) and CPP (Catalytic Pyrolysis Process), are introduced. The commercial experience of the former was reported in 16thWPC and the latter is highlighted in the present paper. Their reaction mechanisms, technology characteristics and commercial results are presented. Discussion is also made on the possibility of adjusting the propylene/ethylene ratio in olefin production.
BLOCK 2 - - FORUM 9 205 OLEFIN PRODUCTION