(424j) Simulation and experiments of biomass pyrolysis for fuel gas with calcium oxide

In this study, the technical route of biomass pyrolysis in-situ CO₂ absorption with CaO has been proposed in order to get high-quality fuel gas. The optimum operation parameters were investigated with combination of experiments and simulating calculations, which will be the foundation of the large-scale application of this technology.

Through the simulations of thermodynamic equilibrium, the effects of temperature, pressure, mass ratio of CaO to sawdust (Ca/B) on the products distribution of the biomass pyrolysis in-situ CO₂ absorption were investigated. It indicated that atmospheric pressure, 700 ℃ and Ca/B of 0.65 would be the suitable operating conditions to produce the high quality fuel gas with good economic prospects. Based on the results of calculation, one system of a moving bed pyrolyzer coupled with a fluid bed combustor (MFS) has been used to produce high quality fuel gas. With the operating conditions of pyrolysis temperature of 700℃, 0.65 of Ca/B and atmospheric pressure, the experiments were carried out in MFS system. The average contents of H₂ and CH₄ were about 40 vol.% and 26 vol.%, while those of CO and CO₂ were about 17 vol.% and 4 vol.%, respectively. LHV of the produced fuel gas was above 16 MJ/Nm³. Cold gas efficiency of the system reached 51.2% through the analysis of system energy. Therefore, with high efficiency and simple operation, this technology may be a promising route to achieve high quality fuel gas for biomass utilization.