Studies On Two-Stage Riser Catalytic Cracking With Stratified Injections Of Various Feeds For Maximizing Propylene

Because of the shortage of petroleum resource and the light oil resource in our state, the catalytic cracking of heavy oil has become an important part in refining industry. Along with the trend of refining and chemical becomes more and more evident, propylene as one of the petro-chemical material, the conflict between supply and demand become more and more acuity. Propylene maximum put forward an austere requirement for catalytic cracking units around the world. Two-stage riser fluid catalytic cracking (TSRFCC) technology can carry out catalytic relay, short reaction time, large catalytic to oil ratio operation because of subsection reaction, favoring the production of propylene with heavy oil."High temperature, large catalyst to oil, short resident time"are favorable conditions for converting C4 mixture and light gasoline to propylene, while"low temperature, large catalyst to oil, fitting resident time"are favorable conditions for converting heavy oil to propylene. Based on TSRFCC technology, stratified injection technology for maximizing propylene are studied, which is TSR-Maximizing Propylene (TMP) technology. The C4 mixture gas, light catalytic cracking gasoline (i.e light gasoline, LCG) and cycle oil (or heavy feedstock oil) produced from the first stage riser are injected into the second stage riser reactor for further refining, realizing the aim that different feedstocks react under"fitting reaction temperature, fitting resident time and large catalyst to ratio". The technology can maintain gasoline yield and octane number, decrease olefin content in gasoline, produce more propylene while decrease low-value products just like dry gas and so on. The experiment utilizes pilot unit to simulate the TMP technology. The reaction conditions, the stratified injection position and the matching catalysts are primary researched.The experiment results show that using TSRFCC technology and stratified injection technology, with Daqing AR as feedstock, the total conversion can reach above 90wt%, the dry gas yield can be restricted to 5.18wt%, propylene yield can reach 21wt%, gasoline and diesel yield are 24wt% and 16wt%, respectively. The olefin content in gasoline can decreased to 33wt%, the octane number is higher, exploiting an effective approach for maximizing propylene with heavy oil and TSRFCC technology.