System for the prevention of dioxin formation in combustion flue gases
AssigneeBeco Engineering Company
InventorBernard J. Lerner
Life of this patent
Estimating the term…
Abstract
Environmental release of carcinogenic polychlorinated dibenzo-dioxins and polychlorinated dibenzo-furan compounds that typically result from combustion of materials containing chlorine or hydrochloric acid-generating components is minimized by preferential sorption of the precursor reactants on sorbents added to exhaust gas at high temperatures containing such precursors prior to conversion of the precursors to carcinogenic compounds normally occurring as the exhaust gas is cooled.
Claims44
A process for minimizing formation of polychlorinated benzodioxin and benzofuran compounds from organic precursor reactants thereof in waste exhaust gases, which process comprises:
- contacting combustion process fly ash and combustion exhaust gases containing organic precursor reactants of polychlorinated benzodioxin, polychlorinated benzofuran compounds or mixtures thereof with substantially dry, finely divided, solid, macroporous, sorbent material, said sorbent material being substantially free of chloride-reactable transition metals, at a temperature compatible with the thermal and chemical stability of said sorbent material, to form a first stream,
- cooling said first stream to adsorb said organic precursor reactants on said sorbent material with substantially no conversion of said adsorbed organic precursor reactants to polychlorinated benzodioxin or benzofuran compounds, to form a second stream comprising a cooled gas stream containing combustion process fly ash and spent sorbent,
- passing said second stream to a solids separation zone for removal of particulate matter comprising said spent sorbent and said fly ash from said second stream,
- removing said particulate matter and withdrawing a gas stream substantially free of polychlorinated benzodioxin and benzofuran compounds.
A process for minimizing formation of polychlorinated benzodioxin and benzofuran compounds from organic precursor reactants thereof in waste exhaust gases, which process comprises:
- contacting combustion process fly ash and combustion exhaust gases containing organic precursor reactants of polychlorinated benzodioxin, polychlorinated benzofuran compounds, or mixtures thereof with substantially dry, finely divided, solid, macroporous, acid-treated sorbent material, said acid-treated sorbent material having been subjected to acid washing to remove chloride-reactable transition metals, at a temperature compatible with the thermal and chemical stability of said acid-treated sorbent material to form a first stream,
- cooling said first stream to adsorb said organic precursor reactants on said acid-treated sorbent material with substantially no conversion of said adsorbed organic precursor reactants to polychlorinated benzodioxin or benzofuran compounds, to form a second stream comprising a cooled gas stream containing combustion process fly ash and spent acid-treated sorbent,
- passing said second stream to a solids separation zone for removal of particulate matter comprising said spent sorbent and said fly ash from said second stream,
- removing said particulate matter and withdrawing a gas stream substantially free of polychlorinated benzodioxin and benzofuran compounds.
A process for minimizing formation of polychlorinated benzodioxin and benzofuran compounds from precursor reactants thereof in exhaust gases, which process comprises:
- burning chlorine-containing fuels in a combustion zone to form combustion process fly ash and combustion exhaust gases containing organic precursor reactants of polychlorinated benzodioxin compounds, polychlorinated benzofuran compounds, or mixtures thereof,
- introducing substantially dry, finely divided, solid, macroporous, acid-treated sorbent material into said combustion zone or upon leaving said combustion zone at temperatures compatible with the thermal and chemical stability of said acid-treated sorbent material to admix with said combustion gases and form a first stream comprising combustion fly ash, acid-treated sorbent material, and said organic precursor reactants, said acid-treated sorbent material having been subjected to acid washing to remove chloride-reactable transition metals,
- cooling said first stream to adsorb said organic precursor reactants on said acid-treated sorbent material with substantially no conversion of said adsorbed organic precursor reactants to polychlorinated benzodioxin or benzofuran compounds, to form a second stream comprising a cooled gas stream containing combustion process fly ash and spent acid-treated sorbent,
- passing said second stream to a solids separation zone for removal of particulate matter comprising said spent sorbent and said fly ash,
- and withdrawing a gas stream substantially free of polychlorinated benzodioxin and benzofuran compounds.
Dependencies are inferred from the claim text.