Abstract: In order to reduce the fuel oil yield and increase the propylene yield, light gasoline distillates with high olefin content can be sent back to MIP unit for reprocessing. There are four ways of light gasoline refining methods: light gasoline is refined in a separate riser, light gasoline is used as quench oil into MIP reactor, light gasoline is recycled to the bottom of pre-lifting zone of the riser, and light gasoline is refined in a separate refining nozzle (below the heavy oil nozzle). After comparison and analysis, it was found that the reaction time and depth could be adjusted by adding a new light gasoline recycling nozzle under the heavy oil nozzle, the product distribution of light gasoline reaction was reasonable, the negative impact on MIP product properties was small, and the economic benefit was good.

Key words: FCC, MIP, light gasoline, proplyene