Techno-economic and scalability analysis of nitrogen plasma gasification of medical waste

Abstract

Plasma gasification by which high-temperature plasma jets can be used to rapidly kill various pathogens and produce syngas and other valuable products, is among the most promising technologies for medical waste treatment. Due to the oxidizing and ablative effect of oxidizing gases on plasma torches, this study uses nitrogen as the working gas for plasma torches. This work introduces a hybrid model implemented in Aspen to assess the impact of temperature and gasifying agent flow rate ratios on the molar fractions of constituents in the syngas generated from four types of medical waste: plastic, rubber, fiber, and biomass. Thereafter, the optimal gasification temperatures and flow ratio of gasifying agent were determined. Furthermore, two scalable systems based on nitrogen plasma gasification of medical waste were proposed, one is syngas to power system and the other is syngas to hydrogen system, which realize profitability while harmlessly treating medical waste. Energy and economic analyses were carried out to promote nitrogen plasma technology as a viable and sustainable waste-to-energy technology. Economic analysis shows that considerable returns can be achieved in a relatively short period of time for both systems (2.57 years of waste-to-hydrogen), which demonstrated the economic viability of nitrogen plasma gasification of medical waste system. A comparison of the two scalable systems reveals that both systems have their own appropriate application scenarios.