Production of highly concentrated propylene and propane fractions at the FCC AGFU

The propane-propylene fraction is widely used in industry, for example in the large-scale process of alkylation of benzene with propylene in the production of phenol-acetone. At the same time, the rectification concentration of propylene from the propane-propylene fraction produced at an absorption gas fractionation plant as part of a fluid catalytic cracking plant is of practical interest. In order to obtain a fraction with a high propylene content, it is shown that an additional distillation column can be included in the technological scheme of the FCC AGFU to separate propylene (propylene content 99.5% by weight) and propane (propane content 98.1% by weight) fractions from propane-propylene. fractions. The research was carried out using the Honeywell UniSim Design modeling system. The parameters of the fraction components were calculated using the Peng-Robinson method. To estimate the actual number of plates of the projected distillation column, the number of the optimal feeding plate and the corresponding phlegm number, the process of separation of propylene and propane fractions in the Short Cut Distillation column was simulated. The results obtained were reproduced on a distillation column containing 90 three-flow valve plates (the efficiency of the contact device was assumed to be 0.8). The optimal technological and structural parameters of the distillation column, which ensure a clear separation of propylene and propane fractions, have the following values: pressure of the top and bottom of the column Rer= 1600 kPa and Rniz = 1650 kPa; temperature in the condenser Tkon = 38.87 °С and in the reboiler Treb =48.52 °С; phlegm number R = 11; power plate Np =34; the distance between the plates is 500mm. The temperature profile of the column height is given. The rectification column model can be used to evaluate the operating and structural parameters in its industrial design. The inclusion of the proposed column in the technological scheme of the FCC AGFU will allow additional economic benefits to be obtained at the enterprise.