(54g) Process Simulation of Integrated Biomass Torrefaction and Pelleting Plant

Process simulation is a useful technique to perform a detailed mass and energy balance of a system using different operating conditions. design parameters and equipment specifications. Simulation is beneficial to scale-up the process and estimation of the investment costs. The process of torrefied pellet production including different unit operations such as combustion, drying, torrefaction, grinding, and pelletizing was simulated with Aspen Plus software platform. In this study, a process simulation of converting wood chips into torrefied pelleting plant was developed. Drying section was simulated through a solid conventional dryer applying the experimental data for drying kinetics. In the torrefaction section, a two-step kinetic model consists of intermediate products was employed and the solid product, as well as volatile products, were produced at various torrefaction temperature. A volatile stream was considered as a combination of ten major components with fixed composition deriving from the torrefaction experiments of forest biomass. At last, a pinch analysis was implemented, and several scenarios were proposed based on different capacities. The size reduction section and pelletizing were also modeled based on experimental particle size distribution and industrial energy consumption data. This simulation model might be applied to a wide range of feedstock types through woody biomass to energy crops, and the effects of various process parameters on the production cost and environmental impacts can be evaluated.

Keywords: process simulation, torrefaction, drying, pelletizing, Aspen Plus