Fume treatment system and method

Abstract

A fume treatment system and method for treating a fume stream emitted from the mouth of a furnace chamber of a metal reclamation furnace system during a portion of the reclamation process includes an auxiliary hood that is smaller than the main overhead hood and is movable between an operative position over the furnace chamber mouth within the main overhead hood for collecting the fume stream emitted by the furnace chamber mouth and another position spaced from, the furnace chamber mouth. An incinerator is in fluid communication with the auxiliary hood when in the operative position. A fume stream blower causes the fume stream collected by the auxiliary hood when in the operative position to flow to the incinerator for incinerating hydrocarbons or other combustible compounds present in the fume stream during operation of the incinerator. A cyclone may be in the flow path between the auxiliary hood and the incinerator for removing particulates from the fume stream prior to entering the incinerator. Also a heat exchanger may be downstream of the incinerator for reducing the temperature of the fume stream exiting the incinerator prior to returning the fume stream to the main overhead hood for further processing.

Description

FIELD OF THE INVENTION [0001] This invention generally relates to a system and method for treating the fume stream from furnaces including particularly tilting rotary furnaces used in the reclamation of ferrous or non-ferrous metals such as aluminum from scrap or dross. BACKGROUND OF THE INVENTION [0002] During the reclamation of ferrous or non-ferrous metals such as aluminum from scrap, the removal of particulate material and volatile pollutants such as hydrocarbons and other combustible compounds including volatile organic compounds (VOCs) from the fume stream rendered by the scrap is oftentimes a problem. Usually the cheaper the scrap, the more the scrap gives off these particles and pollutants. These fume streams can generally be converted to forms of emissions that are within the acceptable limits of pollution control regulations using an afterburner arrangement to incinerate or oxidize the hydrocarbons or other combustible compounds (including VOCs) in the stream. [0003] There...

AI Technical Summary

Benefits of technology

[0005] The system and method of the present invention are designed to capture and incinerate only the portion of the fume stream emitted from the furnace chamber during the metal reclamation process that contains the majority of the hydrocarbons and other combustible compounds (including VOCs), not the entire volume of the air stream collected by the main large overhead hood during the reclamation process. This minimizes the volume of gases the fume treatment system is required to process. Moreover, since the majority of the volatile compounds have been removed from the air stream prior to entering the bag house, the possibility of an exothermic reaction during post processing of the air in the bag house or other post treatment system is significantly reduced. Also this may permit a reduction in the size of the bag house or any other post treatment system required to treat the air stream.

[0012] In accordance with another aspect of the invention, the fume stream that is directed back to the main overhead furnace hood from the heat exchanger may be combined with ambient air to further reduce the fume stream temperature.

Problems solved by technology

During the reclamation of ferrous or non-ferrous metals such as aluminum from scrap, the removal of particulate material and volatile pollutants such as hydrocarbons and other combustible compounds including volatile organic compounds (VOCs) from the fume stream rendered by the scrap is oftentimes a problem.

However, in the case of metal reclamation furnace systems that utilize a main large overhead hood to capture the fume stream, the capture velocity dictates high air flows.

The burner to control and operate an afterburner incinerator to treat this magnitude of air flow is quite large and expensive.

Further there is the problem of how to treat the large amounts of hot air coming out of an afterburner incinerator.

Alternatively, if the hydrocarbons and other combustible compounds are not incinerated out of the air stream prior to entering the bag house, the combustible compounds that are collected in the bag house have the potential to cause a bag house fire.

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