Investigation of factors affecting performance of a downdraft fixed bed gasifier using optimized MLP neural networks approach

A review of the thermochemistries of biomass gasification and utilisation of gas products

“…22 Some relatively new and innovative gasiers such as entrained ow gasiers, 23 plasma gasiers 24 and fountain enhanced spouted conical gasiers 28 appear to be promising in terms of gasication efficiencies as shown in Tables 2-4. [23][24][25][26][27][28] Fluidized bed gasiers, including bubbling and circulating uidized bed reactors, have gained popularity in biomass gasication research and industrial applications. [25][26][27] These gasiers provide several advantages, including efficient mixing of biomass with the gasifying agent, high throughput processing, uniform temperature distribution throughout the reactor, and enhanced heat transfer between the solid biomass particles and the gas phase.…”

“…[23][24][25][26][27][28] Fluidized bed gasiers, including bubbling and circulating uidized bed reactors, have gained popularity in biomass gasication research and industrial applications. [25][26][27] These gasiers provide several advantages, including efficient mixing of biomass with the gasifying agent, high throughput processing, uniform temperature distribution throughout the reactor, and enhanced heat transfer between the solid biomass particles and the gas phase. These features contribute to improved gasication kinetics by promoting rapid reactions and maximizing the utilization of biomass feedstock.…”

“…The co-current ow pattern ensures that the desired gasication reactions occur in the optimal temperature range, enabling higher conversion of the biomass into syngas, promoting efficient tar cracking, leading to cleaner syngas production. [23][24][25] For updra xed bed gasiers (biomass ows from the top and gasifying agent from the bottom), like the downdra type, well-dened zones for biomass drying, pyrolysis, reduction and combustion can be observed. [25][26][27] Hence, as the main feature, updra gasiers have high thermal efficiency due to the positioning of the combustion zone at the bottom bed, while hot gases sequentially pass through the reduction, pyrolysis and drying zones.…”

“…[23][24][25] For updra xed bed gasiers (biomass ows from the top and gasifying agent from the bottom), like the downdra type, well-dened zones for biomass drying, pyrolysis, reduction and combustion can be observed. [25][26][27] Hence, as the main feature, updra gasiers have high thermal efficiency due to the positioning of the combustion zone at the bottom bed, while hot gases sequentially pass through the reduction, pyrolysis and drying zones. The main disadvantage of the updra xed bed gasier is the excessive formation of a complex and oen corrosive mixture of condensable vapours known as tar.…”

“…The formation of tar varies with the type of gasier used. [25][26][27][28] Downdra xed bed gasiers produce low tar yields in the range of 1%, while updra xed bed gasiers can produce between 10 and 20% tar. 16 For uidised bed gasiers, tar yields range from about 1 to 5%.…”