Experimental Gasification of Biomass in an Updraft Gasifier with External Recirculation of Pyrolysis Gases

Abstract

The updraft gasifier is a simple type of reactor for the gasification of biomass that is easy to operate and has high conversion efficiency, although it produces high levels of tar. This study attempts to observe the performance of a modified updraft gasifier. A modified updraft gasifier that recirculates the pyrolysis gases from drying zone back to the combustion zone and gas outlet at reduction zone was used. In this study, the level of pyrolysis gases that returned to the combustion zone was varied, and as well as measurements of gas composition, lower heating value and tar content. The results showed that an increase in the amount of pyrolysis gases that returned to the combustion zone resulted in a decrease in the amount of tar produced. An increase in the amount of recirculated gases tended to increase the concentrations of H2and CH4and reduce the concentration of CO with the primary (gasification) air flow held constant. Increasing the primary air flow tended to increase the amount of CO and decrease the amount of H2. The maximum of lower heating value was 4.9 MJ/m3.

Thermodynamic Model for Updraft Gasifier with External Recirculation of Pyrolysis Gas

“…Modeling starts with the approach to the process of experiments that have been carried out by Surjosatyo et al [4] as shown in Figure 1. Furthermore, the approaches are used to facilitate the simulation process.…”

“…The updraft gasifier has many advantages but, on the other hand, produced high level of tar [1]. Several modifications to gasifier with recirculation of pyrolysis gas have been conducted to reduce the tar [2][3][4]. In previous study, we have modified type of updraft gasifier with pyrolysis gas recirculated externally to the combustion zone.…”

“…In previous study, we have modified type of updraft gasifier with pyrolysis gas recirculated externally to the combustion zone. Furthermore, the produced gas exits at the reduction zone (side stream) to reduce the tar [4].…”

“…In this study, we use a model using two processes of decomposition (decomposition of fuel and char) using the ultimate analysis of fuel and char. The model is implemented on updraft gasifier with external recirculation of pyrolysis gas [4].…”

Air Intake Modification for Pyrolysis Optimization on Rice Husk Fixed Bed Downdraft Gasifier with Maximum Capacity of 30 Kg/hour

“…In this experiment, a reactor design with low tar content and high efficiency gas was obtained by adjusting the exit position of producer gas from the gasifier (Surjosatyo et al, 2014). Another experiment was conducted in Plered, Purwakarta using coconut shell, wood and rice husk as fuel.…”