Pyrolysis Of Heavy Oil Model Compounds To Acetylene By Rotating Arc Hydrogen Plasma

Heavy oil is the strategic energy in the 21 st century. How to convert the heavy oil efficiently is an important subject of the refining industry. However, due to the complex composition, high viscosity and high content of nitrogen, sulfur and metallic element, the processing and utilization of heavy oil is difficult. At present, the best technology which could be applied to all kinds of heavy oil doesn’t exist. Thermal plasma is a non-pollution technology with high efficiency and low energy consumption to convert hydrocarbons such as natural gas, liquefied petroleum gas and oil into acetylene. Pyrolysis of heavy oil to produce acetylene is a promising way of heavy oil processing. Thus, this thesis investigated the pyrolysis of heavy oil by rotating arc plasma based on the investigation of model compound pyrolysis, kinetic model research in order to study the basic law and optimize process conditions.Pyrolysis of n-hexane and toluene are investigated by rotating-arc hydrogen plasma. The key factors such as the mole ratio of H/C (RH/c), input power and magnetic induction are studied. It is shown that n-hexane has better pyrolysis results than toluene. A low RH/c would course low yield of C2H2, low specific energy consumption and serious coking, in consideration of energy consumption, the RH/c-6 would be fine. The input power has optimum value in both n-hexane and toluene pyrolysis experiment. The magnetic induction has no significant effect on the pyrolysis of n-hexane, but it has obvious influence on the pyrolysis of toluene. The yield of C2H2 in the n-hexane pyrolysis experiment reaches 83.01% with the SEC at 13.73 kWh/kg·C2H2; the yield of C2H2 in the toluene pyrolysis experiment reaches 68.65% with the SEC at 21.40 kWh/kg·C2H2. The results of this work are better than others.The kinetic simulations of plasma pyrolysis process are made using plug flow reactor module in Chemkin-PRO. Homogeneous kinetic model and heterogeneous kinetic model are used in the simulations. Comparing with the experimental data, the simulation results of heterogeneous kinetic model are closer to the experimental value than homogeneous kinetic model. This model could predict the influence of H/C and input power to select better experimental conditions. The product distribution in the reactor can be analyzed by the model. The maximum acetylene concentration is 15.22% at 81.34 mm under arc (residence time 2.73 ms) in n-hexane pyrolysis; in toluene pyrolysis, the maximum acetylene concentration is 13.82% at 35.30 mm under arc (residence time 0.90 ms).Pyrolysis of modelling vacuum residuum and vacuum residuum solution are investigated by rotating-arc plasma reactor. The modelling vacuum residuum has the same ratio of aromatic carbon with the vacuum residuum. In the pyrolysis gas the concentration of acetylene reaches 10.21%, the yield of acetylene is 72.87% with the SEC at 16.29 kWh/kg·C2H2. In the pyrolysis experiment of vacuum residuum solution, the acetylene yield is reduced with the increasing concentration of vacuum residuum the best value increased with the increase of concentration of vacuum residuum. After fitting the experimental results, the equation for maximum acetylene yield changing by residuum concentration in the feedstock as follow: y= 83.532-79.33736x Where the x is the concentration of the vacuum residuum, y is the acetylene yield. The equation shows that the contributions of vacuum residuum to the acetylene yield is very low under the present conditions. Preheating the vacuum residuum to improve the mixing effect, reducing the residence time and speeding the quenching rate could improve the result.