Building Delayed Coking Kinetic Model With Structure Oriented Lumping New Method And Study On Its Application

Optimization of delayed coking is a main method to meet the problem that crude oil becoming heavier and worse and increase the heavy oil processing level. Optimizing with lumped kinetic model is convenient and reliable; it is an effective way to process optimization. Structure Oriented Lumping (SOL) new method achieved molecular level lumping with new concept. Build kinetic model with SOL method will increase applicability and commodity of the model largely.Firstly, the molecular composition of delayed coking feedstock has been simulated. After doing some modifications to original structure vectors,92 kinds of single-core and 46 kinds of multi-core seed molecules, totally 7004 kinds of molecular lumps were proposed to represent the molecular composition of delayed coking feedstock. Combining with optimizing algorithm and molecular lump database, the paper proposed a new method to calculate the molecular composition of heavy oil. The method reflected the composition and contents of molecular lumps of heavy oil. The calculation bulk properties of simulated heavy oil agreed with true values well.Secondly, paper used 92 kinds of reaction rules to describe the reaction behaviors of delayed coking, used computer software and regress algorithm to estimate the reaction rate constants of delayed coking, built a delayed coking SOL model with the function of predicting product distribution as the form of solving kinetic simultaneous differential equations, and compiled the interface and processing package. The model reflected real molecular reaction behaviors well, and had a good material flexibility and product distribution predict functions. To ensure the rationality of model test and next calculation, paper checked the reliability of DVS-JHJL-1130 delayed coking experimental device. The reliability of delayed coking experimental device was proved by the comparison of experimental data and industrial statistics data from Sinopec. Based on this, paper checked the reliability of the proposed model on different feedstock under different operating conditions with experimental data and industrial data. The results shows that, model predict results agreed with experimental results and industrial average results well. The relative errors are less than 10%.Thirdly, the effects of feedstock properties on liquid yields of delayed coking were analyzed by the proposed model, and do delayed coking materials composition optimization. Under the operating condition of 480℃,0.15MPa and 0.3 recycle ratio, model calculation and experiments on different material residues mix have been done. The results show that:mix 2# with 4# residue (7:3) will increase liquid yields 1.22% than sum of them coking independent under industrial operating conditions.Fourth, paper analyzed the possibility of recycling waste road asphalt as delayed coking new feedstock with the proposed model. The results shows that:recycling waste asphalt has saturates and aromatics, and the long side chains in resins and asphaltenes could also be break in delayed coking process, so it could be a new mix feedstock of delayed coking. However, coke yields were high to 70% when recycling waste asphalt as delayed coking feedstock directly. It is hard to satisfy the requirements of delayed coking and easy to block up. So, it is better to mix with residues. After calculating the results of residue and recycling waste asphalt co-coking with the SOL model, liquid yields of co-coking were decreased with the increasing of asphalt mixing ratio while gas and coke increasing, coke yields of co-coking were decreased with the increasing of reaction temperature and time while gas and liquid yields increasing. In view of device blocking and safety, the upper limit of asphalt mixing ratio was 20% and temperature and reaction time of co-coking also needed to be limited when do residue and asphalt co-coking experiments on the delayed coking experimental device.Lastly, experiments of residue and asphalt co-coking were carried out on the experimental device under the conditions of 470℃,0.15MPa and 0 recycle ratio. Recycling waste road asphalt was simulated by RTFOT experiments. Asphalt mixing ratio was 20%. Comparing with 80% residue coking, gas, liquid and coke yields of after-mixing were increased 2.3%,2.91% and 14.79% respectively. Economic benefit estimate shows that:residue and asphalt co-coking is helpful for environmental protection and economic benefit. After mixing, olefins in gas were increased. The quality of gasoline and diesel were similar. The quality of wax oil and coke were decreased. Carbon residue, heavy components, sulfur, nitrogen and metal content in wax oil were increased; ash and sulfur content in coke were increased. The wax oil from after-mixing was still accord with the standard of catalytic cracking feedstock. The coke turned to 3B from 3A, but it still could be used as fuel. This developed a new way to deal with the problem how to used recycling waste asphalt well and extend the material of delayed coking.