PYROLYSIS SYSTEMS
Plasma gasification departs from typical gasification by
the addition of electricity to the combustion chamber.
In plasma gasification, fuel or waste is fed to a
reactor vessel where an electrically generated plasma at
a temperature of 20,000 C° is present. When the fuel or
waste is exposed to the plasma it is heated to a very
high temperature (>2,000C°), which causes the organic
compounds in the fuel or waste to dissociate into very
simple molecules such as hydrogen, carbon monoxide,
carbon dioxide, water vapour and methane. These simple
molecules, that are all gases, are allowed to
continuously flow from the reactor to gas cooling and
cleaning equipment. Ash and other inorganic material
present in the fuel or waste is melted down to a complex
liquid silicate that flows to the bottom of the reaction
vessel. Metals that are present also melt and flow to
the bottom of the reactor vessel, where they can either
mix with the silicate, or if present in a large enough
quantity, float on the bottom of it as a separate layer.
The liquid melt is allowed to flow continuously from the
vessel to a water quench where the liquid silicate melt
is cooled to a non leachable, non toxic, obsidian like
solid silicate. Some metals are not melted. Instead,
they vapourise and pass out of the reactor vessel with
the gases formed by the organic material.
When they enter the cooling equipment for the gases,
they condense to fine metal particulates. Halogen and
sulphur compounds present in the fuel are converted to
hydrogen halides and hydrogen sulphide, and pass out of
the reactor with the other gases.
The gas from the reactor has a low to medium calorific
value, and is therefore suitable as the fuel for a gas
fired power generation unit. However, after leaving the
reactor, the gas is still contaminated with a number of
undesirable compounds, such as hydrogen chloride and
metal particulates, that can cause damage to machinery
and the environment. The gas is therefore cleaned in
various process equipment. The cleaned gas, similar in
quality to natural gas, is then fed to a compressor and
storage facility ready for use. The most typical use of
the gas is as fuel for power generation, although it can
also be used as a feedstock for chemical processes. For
example, the production of methanol. When used as a fuel
for power generation, more power is usually produced
than is consumed by the gasifier. Therefore, electrical
power can be exported for sale, or used for onsite
purposes. For high calorific value wastes and fuels the
power exported can be four times that consumed by the
gasifier. For more information visit
safewasteandpower.com
