Effect of Gasification Temperature on Synthesis Gas Production and Gasification Performance for Raw and Torrefied Palm Mesocarp Fibre

Abstract

Biomass gasification is widely used for converting solid biomass into synthesis gas for energy applications. Raw biomass is commonly used as feedstock for the gasification process but it usually contains high moisture content and low energy value which lowering synthesis gas production. Thus, torrefaction as a pre-treatment process is necessary in order to upgrade the properties of feedstock for producing more synthesis gas production and improving gasification performance. The objective of this work is to study the effect of gasification temperature on the synthesis gas production and gasification performance using raw and torrefied palm mesocarp fibre (PMF). The gasification process is conducted using bubbling fluidized bed using steam as gasifying agent. Based on experimental work, by increasing gasification temperature from 650 – 900 °C, the compositions of hydrogen and carbon monoxide gases were enhanced greatly while carbon dioxide and methane gases were decreased for both raw and torrefied PMF. In terms of gasification performance, synthesis gas yield for raw and torrefied PMF is increased from 0.91 to 1.23 Nm3/kg and 1.10 to 1.35 Nm3/kg respectively. Besides, lower heating value (LHV) of torrefied PMF is 0.04 MJ/Nm3 higher than raw PMF at 900 °C. The result showed that the percentage of cold gas efficiency (CGE) reached maximum of 67% for raw PMF while carbon conversion (CC) at 85.6% for torrefied PMF at a gasification temperature of 900 °C. The higher CC obtained by torrefied PMF is because of the increment of carbon content from 45.2% to 53.7% as a result of torrefaction. Gasification temperature of 800 °C showed the best performance of the PMF gasification since the maximum performances of LHV is achieved and started to decrease once the gasification temperature is operated beyond 800 °C.

Effect of Woody Biomass Gasification Process Conditions on the Composition of the Producer Gas

“…The behavior is consistent with what Almeida et al [39] found during the gasification experiments at 700-950 • C using olive kernels, waste, and bagasse as feedstock, where a significant increase in H 2 , CO, and CH 4 concentrations was observed up to 850 • C, while CO 2 levels decreased. Similarly, the present results agree with the findings of Halim et al [40] of palm fiber gasification at 650-900 • C, where it was found that with increasing temperature, H 2 concentrations and CO concentrations increased, but CH 4 concentrations decreased. The results of Yahaya et al [41] also agree with the current results, which indicate that increasing the temperature from 700 to 900 • C increased CO and H 2 .…”

“…This behavior was also observed by Emami et al [44]. Likewise, CH 4 consumption in R 4 and R 5 reduced its concentration at higher temperatures in the gasification of palm fibers [40] and palm kernel shells [41].…”

“…As the temperature increased, reactions R 2 , R 4 , and R 5 moved toward the production of products, including H 2 and CO. This was also observed by Huang et al [38] and by Halim et al [40], where an increment in H 2 occurred at higher temperatures due to methane dry and steam-reforming reactions (R 4 and R 5 ). This effect on the yield of H 2 was also noticed by Ahmad et al [7] due to the water-gas and steam-reforming reactions (R 2 and R 5 ).…”

“…Some studies have observed the same behavior in CO production as the gasification temperature increases, with a remarkable increase in CO in the gasification of coconut and palm kern shells [41] and empty fruit bunches [42]. Some other studies have reported an equilibrium peak in CO production at 900 • C [40]. Meanwhile, CO has also been observed to decrease with temperature rise, owing to the exothermic oxidation reactions, such as char partial combustion [7].…”