Plasma Gasification Process...

Plasma gasification is a multi-stage process which starts with feed inputs – ranging from waste to coal to plant matter, and can include hazardous wastes. The first step is to process the feed stock to make it uniform and dry, and have the valuable recyclables sorted out. The second step is gasification, where extreme heat from the plasma torches is applied inside a sealed, air-controlled reactor. During gasification, carbon-based materials break down into gases and the inorganic materials melt into liquid slag which is poured off and cooled. The heat causes hazards and poisons to be completely destroyed. The third stage is gas clean-up and heat recovery, where the gases are scrubbed of impurities to form clean fuel, and heat exchangers recycle the heat back into the system as steam. The final stage is fuel production – the output can range from electricity to a variety of fuels as well as chemicals, hydrogen and polymers.

Gasification has a long history in industry where it has been used to refine coal and biomass into a variety of liquid fuels, gases and chemicals. Modern clean coal plants are all gasifiers, and so were the earliest 19th century municipal light and power systems.

Plasma gasification refers to the use of plasma torches as the heat source, as opposed to conventional fires and furnaces. Plasma torches have the advantage of being one of the most intense heat sources available while being relatively simple to operate.

Plasma is a superheated column of electrically conductive gas. In nature, plasma is found in lightning and on the surface of the sun. Plasma torches burn at temperatures approaching 5500ºC (10,000˚F) and can reliably destroy any materials found on earth – with the exception of nuclear waste.

Plasma torches are used in foundries to melt and cut metals. When utilized for waste treatment, plasma torches are very efficient at causing organic and carbonaceous materials to vaporize into gas. Non-organic materials are melted and cool into a vitrified glass.

Waste gasification typically operates at temperatures of 1500˚C (2700˚F), and at those temperatures materials are subject to a process called molecular disassociation, meaning their molecular bonds are broken down and in the process all toxins and organic poisons are destroyed. Plasma torches have been used for many years to destroy chemical weapons and toxic wastes, like printed circuit boards (PCBs) and asbestos, but it is only recently that these processes have been optimized for energy capture and fuel production.

America’s Westinghouse Corporation began building plasma torches with NASA for the Apollo Space Program in the 1960s to test the heat shields for spacecraft at 5500˚C. In the late 1990s, the first pilot-scale plasma gasification projects were built in Japan to convert MSW, sewage sludge, and auto-shredder residue to energy. The Japanese pilot plants have been successful, and commercial-scale projects are under development now in Canada and other countries, by companies such as Alter NRG, from Alberta, Canada.