Analysis of sorption-enhanced gasification for production of synthetic biofuels from solid biomass

Abstract

Anthrophonic greenhouse gas emissions have led to climate change. The transportation sector is one of the most significant greenhouse gas emitters. Mitigation of carbon dioxide (CO2) emissions from transportation is a great challenge. Fossil CO2 emissions of the transportation sector can be mitigated with the help of synthetic biofuels. Synthetic biofuels can be produced from biomass by combining the gasification process with the biofuel synthesis process. Sorption-enhanced gasification (SEG) is a promising indirect gasification process for the production of synthetic biofuels. The process has been demonstrated at a pilot-scale. However, a thorough understanding of the physical operation of the reactor still lacks. Establishing modelling capability is an essential step in the studying of new processes. Modelling enables cost-effective techno-economic feasibility evaluation of the process in different size scales before manufacturing the physical equipment.

In this thesis, the SEG is studied for the production of synthetic biofuels from biomass. The thesis consists of the development of modelling tools, a study of the physical operations of the process and the development of an industrial-scale reactor concept for the process. The goal of this thesis is to develop an industrial-scale SEG process for biofuel production. This goal is achieved by studying the process at a pilot-scale before the development of the industrial-scale reactor. A one-dimensional fluidised bed model frames were created for the pilot-scale and the industrial-scale processes. The models combine conservation of mass and energy with semi-empirical model equations for physical phenomena.

The model frame for the pilot-scale process was successfully validated against data from a 200kWth pilot process and other studies in the literature. The model was applied to study balances of a dual fluidised bed SEG process. A quantitative understanding of the physical operation of the SEG process was obtained from the model validation. Based on this knowledge, an industrial-scale process concept was developed for synthetic dimethyl ether production. The designed industrial-scale reactor provides practical information to support industrial-scale plant design and assessing operational performance and cost.