Plasma method for disposing of waste material, and apparatus therefor

Abstract

A method and an apparatus based on a reactor vessel (201) that is brought to a predetermined vacuum degree, in particular said vacuum degree set between 2 and 6 absolute millibar, an to a high temperature. A waste material is continuously introduced in the vessel (202), in particular a solid waste material (5) is introduced in such a way that a vacuum loss from the vessel (201) is prevented. Owing to the high temperature, waste material (5) forms a plasma that undergoes a molecular rearrangement, which gives origin to a substantially liquid residue that is collected in a bottom portion (204) of reactor (201), and to a gas (11). The gas (11), which mainly comprises carbon monoxide, hydrogen, carbon dioxide and steam, i.e. a typical syngas composition, is continuously taken away from the vessel (201) through a duct (12), and is sent to subsequent treatments to obtain a gas fuel that can be burnt by devices such as a gas turbine, a motor or a boiler. The high temperature in reactor (201) is maintained due to a current in the form of electric discharges (20) that is established between two electrodes (21,22) below the liquid head (7). The substantially liquid residue is periodically discharged to maintain a liquid head height (7) not exceeding a reference height value H*, in such a way that air inlet into vacuum loss from the vessel (201) is prevented.

Description

FIELD OF THE INVENTION[0001]The present invention relates to a method for disposing of a waste material, which provides a transformation of the waste into a plasma. The invention also refers to an apparatus for carrying out the method.[0002]The method and the apparatus are well suited for treating a solid, liquid or gas waste material, which may contain an organic and an inorganic part. In particular, the waste material may be a municipal waste, a hospital or surgery waste, a harmful or infected waste, a wastewater sludge, a metal workshop waste, a slaughterhouse waste, a farm waste, a ground tires, etc.BACKGROUND OF THE INVENTION[0003]The need is felt of waste disposal techniques, which overcome the well known drawbacks of traditional techniques, like landfill and incineration, and possibly allow recovering energy.[0004]In particular, methods are known that provide heating a waste material up to a temperature at which the organic part of the waste material turns into a ionized gas,...

AI Technical Summary

Benefits of technology

[0015]It is therefore a feature of the present invention to provide a method and an apparatus for treating a waste material by a transformation into a plasma, in which energy costs are lower with respect to the prior art.

Problems solved by technology

A vacuum higher than what is required to this purpose could not be used in the equipment according to the above mentioned application, as confirmed by the square cross section of the furnace, which is not adapted to work in deep vacuum conditions.

Furthermore, the furnace described in WO2004 / 087840 is not well suited for being steadily fed with solid waste material, without appreciable vacuum loss and / or appreciable air inlet.

In fact, the feeding duct is just equipped with a “isolation valve”, i.e. an on-off valve, which cannot ensure a gas-tight seal.

Similarly, it is quite difficult to feed such a furnace with hermetic, rigid capsules containing dangerous waste material, which would not be safe to open before feeding the furnace, as in the case of infected or harmful waste materials like hospital or surgery waste materials, and the like.

The continuous or periodic removal of the molten residue that is collected in the bottom part of the furnace is complicated by the high temperature that is needed to maintain the liquid state.

Even if “holes for valves” are mentioned, the problem of the lava hardening inside the valves remains unsolved.

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