| FCC as the typical technology of secondary processing to make the heavy oil light plays an important part in improving cracking depth of crude material and optimizing the products distribution. The booming of light olefins such as polypropylene provides broad space for FCC technologies which is one of the most important sources of small molecular olefins. FCC devices gradually has turned into Fuel-chemical type and multifunctional device with high conversion rate, multiple products and high olefin content quality. The yield and propylene concentration of Craking Gas was increased. Wehther absorption-stabilization system and gas fractionation could obtain propylene economically and efficiently has been the important indicator to measure economic benefit of FCC with Fuel-chemical type.This paper proved that C2content in LPG is major factor in limiting propylene yield by calculating material balance and process simulation. Optimizing conditions of gas fractionation could reduce C2content and lessen the propylene loss in deethanizer. When the ratio of C2-/C3=(χ) was lowered to0.004, the qualified propylene yield could over99%are without deethanizer, which is double-tower process. When the ratio of C2-/C3=(χ) was lowered to0.0024futher, the load scope of Depropanizer, propylene rectification and other heat exchangers in the trandittional process still meet device requires of double-tower process.To apply double-tower process, C2content in LPG must be adjusted in absorption-stabilization system.Based on practical production data, The simulation results show that temperature, pressure and liquid in the bottom of desorber effects C2content LPG in cold feeding process of desorber. C2-/C3=(χ) was lowered to0.0024by optimizing conditions. The total yield of propylene by combination of absorption-stabilization system and gas fractionation device improved to98.5%from96.6%, and economic benefit of refining enterprise was improved effectively. |
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