THERMODYNAMIC EQUILIBRIUM ANALYSIS OF RICE HUSK PYROLYSIS

Pyrolysis of biomass materials can implement the efficient conversion of biomass to gaseous, liquid and solid energy products. Compared with experimental research which needs massive apparatus and funds and also takes long time, the computer simulation of biomass pyrolysis is more convenient and flexible to achieve the main characteristics of the process. Simulation of thermodynamic equilibrium for the pyrolysis of rice husk was studied in this paper. Based on the minimization of Gibbs free energy, MATLAB was used to calculate thermodynamic equilibrium for the pyrolysis of rice husk in the temperatures ranges from 523 K to 1723 K at intervals of 100 K. The results showed that the contents of H-2 and CO increased rapidly with the temperature from 723 K to 1223 K, while the contents of H2O, CH4, CO2 and C decreased sharply. When the temperature was higher than 1223 K, the yields of H-2 and CO reached the maximum of 51 mol% and 4 mol% respectively, and then kept stable. In order to be closer to experimental results, the constrain conditions of element C in tar was introduced in the calculations. The results indicated that, in the main components of tar from 523 K to 1223 K, the contents of naphthalene and toluene both decreased and then toluene vanished gradually. However, the content of benzene increased with increasing temperature and finally became the dominant product when the temperature was above 1300 K.