Effect of steam addition for energy saving during CaCO3 calcination of auto thermal biomass gasification

Abstract

Auto thermal biomass gasification produces syngas more energy-efficiently by utilizing the heat released from the reaction between CaO and CO2. The auto thermal gasification process also reduces CO2 emissions and gasification temperature. However, the high temperature required for the regeneration of spent CaO consuming large amounts of energy is a challenge for this process. This paper investigated the effect of steam on the regeneration of spent CaO during biomass gasification from an energy-saving perspective. The modelling results indicated that the regeneration temperature could be lowered with the introduction of steam while maintaining the same 60% CaCO3 calcination efficiency. For example, the introduction of 10 ml h−1 of steam can reduce the regeneration temperature by 50 °C compared to the regeneration under air environment. In addition, SEM and BET analysis confirmed that the steam flow rate needs to be precisely controlled to prevent it from diminishing the surface area of the sorbent and reducing the adsorption capacity of the regenerated CaO.