AC Plasma Arc System for Pyrolysis of Medical Waste and POPs

摘要

Plasma technology is an environmentally friendly method to destruct hazardous wastes. Using the arc discharge with the plasma gas like hydrogen, the temperature can attain 7000°C in arc zone and above 1200～1500°C in reaction zone. Due to such high temperature, the chemical bonds of organic compounds are broken up, and then the process achieves high destruction and removal efficiency (DRE) and avoids the emission of NO_x, CO and dioxins. As the additives such as CaO and SiO_2 are mixed with the wastes, solid by-product of the process is the vitrified slag with some heavy metals in it.In this paper, a pilot-scale AC plasma arc system was designed and installed in the Wastes Treatment Technology lab, Institute of Mechanics, Chinese Academy of Sciences (CAS-IMECH) to investigate the capacity of plasma arc technology for medical waste treatment. The plasma system, with the capacity of 5 ton/day, includes a feed-in subsystem, a 250 kW plasma arc furnace, a monitoring/controlling subsystem, an plasma gas supply subsystem, a water-cooling subsystem, and an off-gas treatment subsystem that consists of a secondary combustion chamber, a fast off-gas cooling heat exchanger, an active carbon-fiber adsorbing box, a wet acid-gas scrubber and an off-gas reheater. The performance characteristics of this plasma arc system has been tested and evaluated. Moreover, cooperating with Mega-Green Environmental Science and Technology Co., Ltd, CAS-IMECH is developing a demo plant for the treatment of Persistent Organic Pollutants (POPs), medical waste and other toxic organic wastes in Xianyang, Shaanxi Province, China.