Energy recovery from pyrolysis and gasification of mangrove

Mangrove is a biomass material that grows in wetland sea waters and is often used to produce charcoal due to its unique characteristics of long and sustained burning and negligible residue. High temperature pyrolysis has been conducted for mangrove biomass in a laboratory scale semi-batch reactor. The effect of reactor temperature on syngas yield and syngas characteristics has been investigated. Reactor temperature was varied from 600 to 900 °C in 100 °C intervals. The increase in reactor temperature resulted in increased syngas yield, hydrogen yield and energy yield. Evolutionary behavior of the syngas characteristics has also been investigated. The increase in reactor temperature increased the peak value of syngas flow rate, hydrogen flow rate and output power. The increase in reactor temperature decreased the time duration of pyrolysis. Cumulative yield of syngas, hydrogen and energy was calculated based on the time dependent relationship. Higher reactor temperatures shortened the time duration required for 99% release of syngas, hydrogen and energy. For example, time duration required for 99% yield of hydrogen was approximately 73 min at 600 °C and only about 26 min at 900 °C. Required time duration for 99% yield of energy was ∼62 min at 600 °C and ∼15 min at 900 °C. The gasification of the same material at 900 °C has been carried out to determine the role of gasifying agent on the fate of material and resulting syngas properties. The results showed gasification yielded more syngas, hydrogen and energy than that obtained from pyrolysis.

► The increase in reactor temperature increased the hydrogen yield and energy yield.
► The increase in reactor temperature increased the peak value of syngas flow rate.
► Cumulative yield of energy was calculated based on the time dependent results.
► Higher reactor temperatures shortened the time duration for 99% release of syngas.
► Gasification yielded more hydrogen and energy than that obtained from pyrolysis.