Reducing mercury emissions from the burning of coal
AssigneeNOx II, Ltd.
InventorDouglas C. Comrie
Life of this patent
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Abstract
Sorbent components containing calcium, alumina, and silica are used in combination during coal combustion to produce environmental benefits. Sorbents are added to the coal ahead of combustion and/or are added into the flame or downstream of the flame, preferably at minimum temperatures to assure complete formation of the refractory structures that result in various advantages of the methods. When used together, the components reduce emissions of elemental and oxidized mercury; increase the level of Hg, As, Pb, and/or Cl in the coal ash; decrease the levels of leachable heavy metals (such as Hg) in the ash, preferably to levels below the detectable limits; and make a highly cementitious ash product.
Claims23
A method for reducing the amount of oxidized mercury in flue gases generated by combustion of a mercury-containing carbonaceous fuel in a furnace, the method comprising
- adding an alkaline powder sorbent onto the fuel before combustion or directly into the furnace during combustion;
- burning the fuel in the presence of the added alkaline powder sorbent;
- measuring the level of mercury in the flue gases;
- comparing the measured mercury level to a target level;
- and
- if the measured value is above the target level, increasing the amount of powder sorbent added relative to the fuel,
- wherein the powder sorbent comprises calcium, silica, and alumina.
A method for reducing leaching of mercury and/or of other heavy metals from ash produced from the combustion of coal or other fuel in a coal burning system or in an incinerator, comprising:
- introducing sorbent components containing silica and alumina into the incinerator or coal burning system during combustion at a rate of addition based on the amount of coal or other fuel being consumed by combustion;
- measuring leaching of mercury and/or other heavy metals from the resulting ash;
- and
- adjusting the addition rate according to the measured leaching of heavy metals.
A method of making coal ash with a targeted low level of leachable mercury, comprising burning the coal in the presence of added calcium, silica, and alumina, measuring the leaching of mercury from the resulting coal ash, and increasing the addition rate of silica and/or alumina if the measured leaching is below the targeted level.
Dependencies are inferred from the claim text.