Gas cleaning from Gasification for Production of Biofuels and Biochemicals
Gas cleaning is a crucial step in the gasification process to producing high qaulity biofuels and biochemicals.
In a gasification process, biomass is converted into ‘producer gas’, which is a mixture of carbon monoxide, hydrogen, methane, and other gases. This raw gas still contains impurities such as tar, sulphur compounds, ammonia, particulates, and heavy metals, etc. which can hinder downstream processing, damage catalysts, and reduce efficiency in fuel and chemical synthesis. Effective gas cleaning ensures high-purity syngas, improving process reliability, maximizing yield, and reducing environmental impact.
Advanced cleaning technologies, including filtration, scrubbing, and catalytic reforming, are essential for achieving the quality standards required for biofuel and biochemical production.
Following the cleaning and conditioning stages, producer gas is upgraded to synthesis gas, or syngas. This refined gas is versatile and can be used in various applications. It can be combusted in internal combustion engines or gas turbines to produce heat and electrical power. Beyond energy generation, syngas serves as a key feedstock for several chemical synthesis processes, including the production of synthetic natural gas, the Fischer-Tropsch process for liquid fuels, hydrogen, methanol synthesis, and further products.
Each of these synthesis processes imposes strict requirements on syngas purity. Impurities such as sulphur, tar, particulates, and other contaminants must be controlled within specified limits to avoid catalyst poisoning, inefficiencies, or equipment damage during processing. These permissible impurity levels are critical for ensuring the effectiveness and longevity of the systems involved and vary depending on the specific catalytic process or chemical conversion being targeted.
A new report by Task 33 (Biomass Gasification) presents a structured review of various syngas cleaning technology. The review concludes with an examination of recent advancements in gas cleaning technologies, with a focus on innovative methods for selectively optimizing syngas quality. These cutting-edge approaches aim to enhance the efficiency and effectiveness of gas purification and conditioning processes.
Biomass-to-liquid route representation, with emphasis on the gas cleaning sequence. The continuous green arrow represents the simplest route. The tar reforming route is marked with a yellow dotted line (the dashed one is an alternative path).
Source: de Oliveira, D. C., et al. (2023). Gas cleaning systems for integrating biomass gasification with Fischer-Tropsch synthesis – A review of impurity removal processes and their sequences. Renewable and Sustainable Energy Reviews, 172, Article 113047. https://doi.org/10.1016/j.rser.2022.113047