Numerical modeling of rice husk gasification in fluidized bed gasifier for sustainable biofuel production

Abstract

Currently, there is a growing interest in various alternative energy sources due to the global energy scenario and rising crude oil prices. Renewable sources of energy like biomass can be exploited to produce energy-rich syngas. The biomass gasification process converts energy-rich solid fuel into syngas by partial combustion. In the present study, rice husk gasification using steam and, a mixture of steam and CO2 at temperatures ranging from 650°C to 750 °C and steam to biomass ratio of 0.5–2 is studied. Steam gasification enhances hydrogen production, and mixing with CO2 helps optimizing the H2/CO ratio. The study uses the Euler-Euler method in combination with kinetic theory granular of flow which is modeled using the computational fluid dynamics approach implementing user-defined functions for heterogeneous char reactions. The increased particle diameter harms the gasification performance due to the lower heating value of the syngas. As the steam to biomass ratio is increased, there is a positive effect on syngas quality, while temperature has a negative effect. The addition of CO2 increases the CO conversion in the syngas. The heterogeneous reaction rate vanishes close to zero after a height of 0.4 m, where all solid carbon is consumed.