Removal of elemental mercury by photoionization
AssigneeThe Johns Hopkins University
InventorJoseph L. Katz
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Abstract
Elemental mercury is removed from emissions of coal-fired utilities by the selective photoionization of mercury atoms using ultraviolet light, followed by electrostatic precipitation of the mercury ions. Mercury is first exposed to light of a wavelength which boosts the mercury to an excited state. Then mercury is ionized using light of a different wavelength. The ionized mercury atoms are exposed to supersaturated water vapor to produce charged droplets which are precipitated, such that the exhaust effluent is substantially devoid of mercury or the mercury level is substantially reduced.
Claims30
A method for removing elemental mercury from an exhaust source comprising the steps of:
- photoionizing elemental mercury in an exhaust to form ionized mercury atoms;
- and
- electrostatically precipitating the ionized mercury atoms from the exhaust.
A method for removing elemental mercury from an emissions source comprising the steps of:
- exposing an emissions source containing elemental mercury to electromagnetic radiation which excites elemental mercury;
- providing additional electromagnetic energy having a combined energy of greater than 5.68 eV to ionize the excited elemental mercury;
- and
- electrostatically precipitating the ionized elemental mercury.
An apparatus for removing elemental mercury from an exhaust source comprising:
- at least one light source for photoionizing elemental mercury in an exhaust to form ionized mercury atoms;
- and
- an electrostatic precipitator for precipitating the ionized mercury atoms from the exhaust.
An apparatus for removing noxious material from an exhaust, comprising:
- means for removing particulate material from the exhaust;
- at least one light source for photoionizing elemental mercury in the exhaust to form ionized mercury atoms;
- an electrostatic precipitator for precipitating the ionized mercury atoms from the exhaust;
- and
- a stack for releasing the exhaust with reduced mercury levels.
Dependencies are inferred from the claim text.