Performance analysis of a co-gasifier for organic waste in agriculture

Agricultural waste has been proposed as an alternative energy resource to meet fossil fuel crisis, green house emission, and other environmental impacts worldwide. In Iran, rice husk and bagasse are main resources of biomass which can be used to produce syngas. This paper deals with a simplified model of combined gasification of coal and biomass processes considering chemical equilibrium.

It should be noticed that the CO2 which is produced from agricultural waste gasification is natural because the biomass absorbs CO2 from nature and gives it back after gasifying; however, mixing agricultural waste with coal leads to enrich syngas quality and gasifier efficiency.

In this regard, an advanced coding was developed to simulate the thermodynamics of the co-gasifier and to find the produced syngas composition. The effects of moisture content, steam-to-biomass ratio, and gasifier temperature are then discussed on the system performance. Additionally, co-gasification of rice husk/coal was compared with co-gasification of bagasse/coal. The results indicated that adding coal to biomass increases lower heating value of syngas from 4,694 kJ/Nm3 to 5,321 kJ/Nm3 and gasifier efficiency from 71.29% to 77.85%.