Torréfaction of Mangrove Wood by Introducing Superheated Steam for Biochar Production

Abstract

Torréfaction by superheated steam was carried out over mangrove wood in a rotary kiln carbonizer. The mangrove wood was obtained from Kuala Sepetang, Malaysia. The current biochar production process still applies the traditional carbonization method, which requires 30 days in hot air. The torrefaction process using superheated steam was performed by manipulating the operating time at 30, 60, 90, and 120 min operating at 300°C. The high heating value (HHV) for raw mangrove wood to solid char product raised from 16.7 MJ/kg up to about 30 MJ/kg. The HHV was 29.7 MJ/kg after 60 min torrefaction. The carbon percent increases from 47.4% to above 70%. For bio-oil products, the superheated steam torrefaction produces various acids, alcohols, ketones, and aldehydes range from 249 ml to 335 ml. In contrast, torrefaction products via hot air carried-out in Kuala Sepetang have a liquid that contains acetic acid, butanoic acid, and phenol. Torrefaction of mangrove wood by superheated steam significantly reduced the biochar production period from 30 days to one-hour operation.