Numerical modeling of a 500 kW air-blown cyclone gasifier

Abstract

Cyclone gasification of biomass in combination with a gas engine has been considered as a process for combined heat and power production. In this work a numerical model of the cyclone gasification process of wood powder was developed intended to be used as a tool for future engineering design of cyclone gasifiers. The model is based on an Euler–Lagrange formulation for the multiphase flow where the biomass powder was treated as a dispersed phase and the gas as a continuous phase. The results from the simulation are compared with experimental measurement in a 500 kWth cyclone gasifier that uses wood powder as fuel. The model was able to predict the gas composition change with increasing equivalence ratio. The relative error for the main gas component was between 2.5 and 4.4%, 2.8 and 5.4%, and 2.6 and 17.3% for CO2, CO and H2. CH4 was predicted with a relative error of between 3.8 and 19.2%. Also the model was able to predict the char amount out from the gasifier with reasonable accuracy. The obtained lower heating value from the model was between 3.5 and 5.2 MJ/Nm3 whereas the calculated based on measurement was 4.0–5.3 MJ/Nm3.