Thermal plasma waste treatment

Abstract

Plasma waste treatment has over the past decade become a more prominent technology because of the increasing problems with waste disposal and because of the realization of opportunities to generate valuable co-products. Plasma vitrification of hazardous slags has been a commercial technology for several years, and volume reduction of hazardous wastes using plasma processes is increasingly being used. Plasma gasification of wastes with low negative values has attracted interest as a source of energy and spawned process developments for treatment of even municipal solid wastes. Numerous technologies and approaches exist for plasma treatment of wastes. This review summarizes the approaches that have been developed, presents some of the basic physical principles, provides details of some specific processes and considers the advantages and disadvantages of thermal plasmas in waste treatment applications.

A critical review on biomass gasification, co-gasification, and their environmental assessments

“…Thermal Plasma treatment has been employed for pyrolysis, gasification, and compaction of waste materials as illustrated in Figure 3 (Heberlein and Murphy, 2008). For the gasification process, plasma is applied: 1) as a heat source during gasification and 2) for tar cracking after standard gasification.…”

Thermal Plasma Gasification of Municipal Solid Waste (MSW)

“…Heberlein and Murphy [32] described that a typical plasma system for the treatment of solid wastes consists of (a) the plasma furnace, with a metal and the slag collection at the bottom that periodically tapped and cast into some usable form and power supply, cooling water supplies, gas supplies, and control and data acquisition equipment; (b) a secondary combustion chamber for allowing sufficient residence time at elevated temperatures to assure complete reactions and gasification of soot; this secondary combustion chamber can be fired either by a burner or by a low power non-transferred plasma torch; (c) depending on the waste, a quenching chamber (usually water quencher) to avoid formation of dioxins and furans; (d) a cyclone or bag-house for particulate removal; (e) a scrubber for eliminating acidic gases; (f) if necessary a hydrogen sulfide absorber; (g) high efficiency filters or precipitators for small particulate removal; (h) an activated carbon filter for removal of heavy metals; (i) finally a fan for generating sub-atmospheric pressure in the entire installation. Additionally, various forms of waste preparation and feeding systems have to be integrated with the furnace.…”

“…The major disadvantage of thermal plasma gasification processes mentioned by many scientists and engineers is the use of electricity, which is an expensive energy source [32]. The economics of thermal plasma gasification processes have many variable parameters such as regional characteristics, types of solid wastes to be processed, capacity, and others.…”

3D static and time-dependent modelling of a dc transferred arc twin torch system

“…The twin torch configuration is schematically represented in figure 2 and refers to a 1 MW mobile twin torch plant dedicated to asbestos inertization from Centro Sviluppo Materiali (CSM) S.p.A, Rome, Italy [2,3]. The computational domain does not extend to the whole reactor, since the simulation of the complete 3D configuration would be too computationally expensive.…”

“…Twin torch generated arcs differ from the other transferred arcs since the anode is not the workpiece, as shown in figure 1, while the arc may or may not pass through a bath of molten material, depending on the specific application or design. This kind of device has been used mainly in reactors for waste treatment incineration and inertization, or for metallurgical applications [2][3][4], while on the patent side also some other applications are claimed [5]. The advantages of such device are: − the arc can be elongated and the energy is exerted directly on the process material or on the surface of the component, the powder, gas or dispersed liquid, not in the torch; − enhanced convection leading to a more homogeneous temperature in the reactor; − electrodes can be protected by inert shrouding gas (e.g.…”