The impact of bed material cycle rate on in-situ CO2 removal for sorption enhanced reforming of different fuel types

A dual fluidized bed reactor system produces a nitrogen-free product gas by using steam as gasification agent. Additionally, the usage of limestone as bed material allows for the in-situ removal of carbon dioxide out of the product gas. Hence, a hydrogen-rich product gas with a high reduction potential for the steel industry can be generated. This so-called “sorption enhanced reforming” process has already been proven applicable for wood as fuel, but since the costs for biomass like wood have increased significantly during the last years, cheaper fuels are of interest. The experimental results of three different biogenic fuel types (soft wood, rice husk and bark) and one fossil fuel type (lignite) are discussed in detail. In the past, research mainly focused on temperature dependency of the process since it seemed to be the main factor for carbon dioxide sorption in the gasification reactor and therefore product gas composition. Within this work, it is shown that the bed material cycle rate should not be disregarded and is a key factor within the process. The presented findings allow a detailed understanding of “sorption enhanced reforming”, the influence of bed material cycle rate, and the influence of volatile matter in the fuel.