Studys On 10-lumped Kinetic Model For Heavy Feedstock Pyrolysis

Ethylene is one of the most important basic feedstocks in the petrochemical industry. At present, the lack of feedstocks lead to ethylene industry becomes a bottleneck of constraint to the development in domestic resources of China. How to reduce the cost of ethylene production and improve the market competitiveness of petrochemical products as a issue need to be solved of ethylene industry in China. The development and use of heavy pyrolysis feedstocks become the key to solve this problem. This article established 10-lumped kinetic model by analysis and improvement of some problems and established method of lumped kinetic of 8-lumped kinetic model according to steam pyrolysis of Daqing heavy naphtha.Firstly, using self-built pyrolysis experiment device to experiment on Daqing heavy naphtha and obtained 80 datas. Through the analysis experiment datas, these datas can reflect the prolysis rules of Daqing heavy naphtha, and can used as kinetic regression basic datas.Secondly, taking into account the diversity in the performance of pyrolysis of Daqing heavy naphtha's n-paraffin, i-paraffin, 5-cyclanes and 6-cyclanes, a 10-lumped kinetic model with 4 stock-lump and 6 product-lump is proposed of Daqing heavy naphtha pyrolysis, and the corresponding reaction network chart and the material balance equations among the lumps were given. Its reaction rate constants were determined by combining the layered-method with the stepwise-method, and using Matlab language and Marquardt++ method to modified and debugged the program of 10-lumped model, and further obtained the activation energy and the exponential gene.Due to large number of reactions of 10-lumped model, so the reactions were divided into upper(material layer) and lower(product layer). Upper's reaction rate constants, belonged in 4 material lumps of n-paraffin i-paraffin, 5-cyclanes and 6-cyclanes, were determined by the stepswise-method. The conception of shallow pyrolysis is introduced in lower's calculate. Obtained the components of lower by combining the experiment and the simulation, and further obtained the reaction rate constants, the activation energy and the exponential gene.Compared 10-lumped model with 8-lumped model, and analyzed the error of the experimental data and the count results. Absolute error of all lumps yields of 10-lumped model account for 98% within 0.5. And relative error account for 95% within 10%, and account for 90% within 5%.The analysis shows 10-lumped model has a better accuracy than 8-lumped model.