Performance evaluation of different combined systems of biochar gasifier, reformer and CO2 capture unit for synthesis gas production

•Different combined systems of biochar gasifier, reformer and CO2 capture are considered.•Performances (various efficiencies and environment) are compared for syngas production.•Combined gasifier and reformer with Pre-CO2 recycle offers highest cold gas efficiency.•Combined gasifier and reformer with Post-CO2 recycle produces syngas with low H2/CO.

The performance of different combined systems of biochar gasifier and reformer, with and without CO2 recycle, was evaluated and compared in terms of cold gas efficiency (CGE), hydrogen content in syngas product, gasification system efficiency (GSE), total net heat, and CO2 emission ratio (CO2EMR). Effects of various operating parameters such as feed ratio and operating temperature were investigated. The biochar, represented by mangrove tree charcoal, steam, O2 and CO2 were used to produce syngas product. The results revealed that the performance of the conventional systems were inferior to the ones with reformer. Increasing operating temperature offered higher CGE and could reduce CO2EMR. Amount of CO2EMR was increased with an increase in O2/C feed ratio but it was an opposite direction at O2/C feed ratio higher than 0.2. Higher S/C feed ratio offered higher H2 content in the syngas product with the limitation of S/C at 1.2. The use of CO2 in the feed produced the syngas product with lower H2/CO. The combined gasifier and reformer with Pre-CO2 recycle (CBGR-Pre-reCO2) was the most suitable process to produce syngas with high CGE while the combined gasifier and reformer with Post-CO2 recycle (CBGR-Post-reCO2) produced syngas with low H2/CO.