Constructing Catalytic Cracking Kinetic Model Based On Structure Oriented Lumping New Method And Study On Its Application

Kinetic model for catalytic cracking can give a guide for optimizing the composition offeedstock and the operating conditions of catalytic cracking unit to increase the economicbenefit significantly in reifnery plant. Based on the molecular lump of petroleum andcarbenium ion mechanism, catalytic cracking kinetic model with Structure Oriented Lumping(SOL) method can describe the process of catalytic cracking reaction on molecular level andpredict product distribution and quality to improve the utilization efficiency of crude oil andenhance the level of informationization in catalytic cracking unit.686kinds of single-core and623kinds of multi-core molecules have been selected todescribe molecular composition for vacuum gas oil and residue through modifying22structure vectors in SOL method. True boiling point distillation unit was used for cuttingvacuum gas oil and residue. A variety of advanced analysis methods such as GC-MS,NMR，FT-IR and GPC have been conducted for obtaining detailed composition, structure andproperties of narrow fractions. Nonlinear regression method has been used to calculaterelative content of every single molecular lump. Structure vector matrix describing formolecular composition of catalytic cracking feedstock has been constructed.112catalytic cracking reaction rules have been formulated to describe catalytic crackingbehaviors according to carbon ion reaction mechanism. Catalytic cracking kinetic model withstructure oriented lumping method has been constructed combining with structural feature ofriser reactor and catalytic performance of CARC-1type of catalyst. Modiifed Runge-Kuttaalgorithm was used to solve the kinetic model. According to the product distribution of typicalfeedstock catalytic cracking, and the rate constants through theoretical calculation for purehydrocarbon and classical linear free energy relationship theory, kinetic parameters have beencalculated by beding divided into tiers and genetic algorithms optimization. UNIFAC methodwas taken to divide calculated product matrix into fractions. Matlab sotfware has been used todevelop sotfware package for catalytic cracking kinetic model with SOL method.Experiments have been carried out on the new riser reactor unit to evaluate the accuracyof catalytic cracking kinetic model with SOL method. The reliability of riser reactor wasverified by comparing with the industrial operating conditions and product distribution data of1#catalytic cracking unit in Sinopec Shanghai GaoQiao Petrochemical Company. Throughthe comparison of constructed SOL method and traditional lumping method of catalytic cracking kinetic model with experimental data on small riser reactor catalytic cracking unit, itshows the SOL model is superior to traditional lumping method on calculated precision. Inaddition. SOL model can obtain molecular composition information of product. As thefeedstock composition, reaction temperature, catalyst/oil ratio (C/O) and retention timechanged, the predicted results by SOL kinetic model agreed well with the experimental results.The relative errors were less than7%. The correction coeiffcient can be added into theconstructed SOL model for predicting industrial product distribution and properties. Thesimulated results also agreed well with the industrial data, with the relative errors less than dry gas and coke yield, the optimized catalytic cracking temperature was500。C, C/O ratio=...