A comprehensive study on kinetics for hydrogen generation from aquathermolysis gasification of heavy crude oil

Abstract

In-situ gasification (ISG) was considered as a promising technology for hydrogen generation and aquathermolysis is one of significant reactions during the prolonged gasification process. Therefore, it is critical to establish the kinetic model and analyze reaction routes for understanding reaction mechanisms. The aquathermolysis experiments were carried out in a closed reactor under the condition of different temperatures (200 °C, 240 °C, 280 °C) and different reaction times (12h, 24h, 48h, 72h). Then a comprehensive kinetic model involving five gas components and four liquid components was proposed to be more detailed description of the reaction process. The kinetic parameters were obtained by fitting experimental data based on Levenberg Marquardt algorithm and Runge-Kutta method, followed by calculating the activation energies by the Arrhenius equation. The rate constants were used to estimate the gases generation rates for analyzing reaction routes. The model presented a great fit suggested by the parity plot and smaller objective function values (SSE). The results showed that methane and HMWG were main from the evaporation of saturates, and asphaltenes gasification were major source of hydrogen, carbon dioxide, and hydrogen sulfide. Besides, methane and HMWG from cracking primarily came from asphaltenes. The kinetic model and its corresponding kinetic parameters could be used to predict the mass fraction of liquid and gas components in aquathermolysis in numerical simulation method, which can assist promoting the development of ISG technology.