Upgrading agricultural wastes using three different carbonization methods: Thermal, hydrothermal and vapothermal

Area of Science:

• Biomass energy conversion
• Thermochemical processing of lignocellulosic materials

Background:

• Agricultural waste, such as oil palm empty fruit bunches, mesocarp fibers, palm kernel shells, and rubber seed shells, presents a significant disposal challenge.
• Developing high-quality solid fuels from biomass is crucial for sustainable energy production and waste valorization.

Purpose of the Study:

• To experimentally compare the effectiveness of thermal (TC), hydrothermal (HTC), and vapothermal (VTC) carbonization for producing high-quality solid fuel from various biomass feedstocks.
• To evaluate the energy densification and fuel properties achieved by each carbonization method.

Main Methods:

• Utilized a custom-made batch-type reactor for TC, HTC, and VTC processes.
• Employed a novel single reactor design integrating a steam generator and raw materials for efficient operation.
• Analyzed biomass feedstocks including oil palm empty fruit bunches, mesocarp fibers, palm kernel shells, and rubber seed shells.

Main Results:

• Vapothermal carbonization (VTC) yielded the highest energy densification, followed by TC and HTC.
• Heating value enhancement in VTC and TC was attributed to increased fixed carbon content and reduced volatile matter.
• HTC hydrochar exhibited spherical components, indicated by a sharp peak at 340°C in DTG curves, contributing to increased energy content.

Conclusions:

• VTC is the most effective method for enhancing the energy density of solid fuels derived from the tested biomass.
• The distinct characteristics of hydrochar produced via HTC influence its energy content.
• Efficient solid fuel production from agricultural waste is achievable through optimized thermochemical processes.