GASIFICATION

Gasification is a thermo-chemical conversion process that transforms carbonaceous feedstocks, like biomass, into a combustible gas mixture known as syngas. This is achieved by partially oxidizing the feedstock at elevated temperatures (typically between 700°C to 1.500°C) in the presence of a controlled amount of an oxidizing agent (air, oxygen, steam, or carbon dioxide).

Key Stages

• Drying: The initial stage involves removing moisture from the biomass. This is crucial to prevent the formation of tars and enhance the overall gasification efficiency.

• Gasification: As the temperature rises, the biomass undergoes gasification, decomposing in almost absence of oxygen to yield char, volatile organic compounds (VOCs), and non-condensable gases.

• Gasification Reactions: The resultant char and VOCs react with the gasifying agent at high temperatures through various chemical reactions:
  

- Partial Oxidation: C + 1/2 O2 → CO

- Combustion: C + O2 → CO2

- Water-Gas Reaction: C + H2O → CO + H2

- Boudouard Reaction: C + CO2 → 2CO

- Methane Reforming: CH4 + H2O → CO + 3H2

• The complex interplay of these reactions, influenced by temperature, pressure, and the gasifying agent, generates syngas, primarily composed of carbon monoxide (CO), hydrogen (H2), carbon dioxide (CO2), and methane (CH4).

• Char Production: A portion of the carbon in the biomass remains unconverted, resulting in the formation of biochar, a carbon-rich solid product.