STTR Phase I: Waste Torrefaction Technology

The broader impact of this Small Technology Transfer Research (STTR) Phase I project is to address sustainability by conversing waste into a clean and renewable resource. Waste incineration has been practiced for some time and brings operational difficulties and high emissions. The proposed project advances a technology to convert waste into a a solid fuel. The proposed project advances a torrefaction solution for industrial use. Torrefied waste is significantly low in hazardous components (chlorine) and can be pulverized, enabling application as a solid renewable fuel. However, waste is a feedstock that is extremely difficult to handle and convey due to low density and large inconsistencies. The chlorine content of waste can (i) cause severe corrosion and (ii) require strict emission control, with significant increase in cost. Further, it cannot be used in pulverized fuel boilers as it is not grindable. This project advances a small torrefaction system (50 kg/hr) addressing these issues by developing: (1) a waste handling unit that downsizes to 2 mm size with a unique feeding system that avoids bridging; (2) a cramming unit that can handle hard to flow and low-density materials; and (3) a cooling system for safety; and (4) a torrefaction-extrusion reactor. This reactor does the following: (i) reduces the organic chlorine to acceptable levels; (ii) decomposes long polymeric chains and makes the material friable, thus grindable; (iii) homogenizes and downsizing the material due to mechanical mixing; and (iv) uses an integrated compaction that reduces footprint and improves the economics. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.