Study On Lumping Kinetics Of Daqing Heavy Naphtha Pyrolysis

At present, with the heavy materialization of pyrolysis feedstock producing ethylene on our country, the proportion of heavy oil in feedstock increases gradually; On the other hand, with the development of computer technology and the urgent process optimization of pyrolysis feedstock producing ethylene, the technology which simulates pyrolysis process also gets great development. The components of heavy pyrolysis feedstock can't be analyzed clearly and its'pyrolysis system is complex and highly coupled. So Daqing heavy naphtha was chosen to experiment on and lumping method was used to establish lump reaction kinetic model for complex reaction in this paper. This method has been applied successful in the process of catalytic pyrolysis, catalytic cracking and catalytic reforming, but not reported in the steam pyrolysis system.In this paper, eighty experiments on Daqing heavy naphtha were done at pyrolysis temperatures from 790 to 830℃, residence time from 0.21 to 0.24s and dilution ratio within 0.45-0.75 using self-built pyrolysis experiment device. Using experiment data pyrolysis reaction rules of Daqing heavy naphtha were further studied and the data were consistent with pyrolysis reaction rules.On the base of five-lump kinetic model of Daqing naphtha pyrolysis, eight-lump kinetic model of Daqing heavy naphtha pyrolysis was established successfully. The corresponding reaction network chart and the mass balance equations among the lumps were given. Computational procedure and method to resolve kinetic parameters were established with Matlab language and Marqudart++ method, and the program was modified and debugged. Then reaction rate constants under different temperatures and frequency factors, activation energy were further calculated. Seen from data, except relative errors of some data range from 10% to 20%, most relative errors are 10% below and the data number of"three alkenes"within 10% reaches up to 98% particularly. Forecasting with this eight-lump kinetic model of Daqing heavy naphtha pyrolysis, the predicted values of the model were quite close to experimental values, so the model could forecast the pyrolysis product yields well.