Reducing mercury emissions from the burning of coal
First Claim
1. A method for reducing mercury in the flue gases resulting from combustion of coal in a coal burning system, comprisingapplying sorbent components into the coal burning system, wherein the components comprise a halogen compound and at least one aluminosilicate mineral;
- combusting the coal to produce ash and combustion gases;
measuring a mercury level in the combustion gases; and
adjusting the amount of halogen compound applied based on the value of the mercury level.
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Accused Products
Abstract
Sorbent components containing calcium, alumina, silica, and halogen 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 mercury and sulfur; ● reduce emissions of elemental and oxidized mercury; ● increase the efficiency of the coal burning process through de-slagging of boiler tubes; ● 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.
196 Citations
61 Claims
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1. A method for reducing mercury in the flue gases resulting from combustion of coal in a coal burning system, comprising
applying sorbent components into the coal burning system, wherein the components comprise a halogen compound and at least one aluminosilicate mineral; -
combusting the coal to produce ash and combustion gases; measuring a mercury level in the combustion gases; and adjusting the amount of halogen compound applied based on the value of the mercury level. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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- 10. A sorbent composition comprising 26 to 98% by weight of an alkaline powder and 2 to 50% of an aluminosilicate mineral, wherein the alkaline powder comprises one or more of Portland cement, cement kiln dust, lime kiln dust, and sugar beet lime.
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15. A process for burning coal to reduce the amount of mercury released into the atmosphere comprising
applying a liquid sorbent composition comprising a bromine compound onto the coal; -
delivering the coal containing the sorbent into a coal burning furnace; injecting a powder composition into the furnace during combustion, the powder composition comprising sources of calcium, silica, and alumina; combusting the coal together with the liquid sorbent and powder composition in the coal burning furnace to produce ash and combustion gases. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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26. A method for burning mercury-containing coal in a combustion system comprising a furnace and convective pathway for flue gases downstream of the furnace, the method comprising:
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adding a liquid composition into the system; adding a powder composition comprising calcium, silica, and alumina into the system during combustion; and combusting coal to produce flue gases and fly ash; wherein the liquid composition comprises a bromine compound and the powder composition comprises at least 2% by weight silica and at least 2% by weight alumina. - View Dependent Claims (27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37)
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38. A method for burning coal with reduced levels of undesirable elements escaping into the environment comprising
adding a sorbent composition comprising calcium, silica, alumina, and a halogen selected from the group consisting of bromine and iodine onto the coal; burning the coal to produce ash and combustion gases. - View Dependent Claims (39, 40, 41, 42, 43)
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44. A method for reducing mercury in the flue gases resulting from combustion of coal in the furnace of a coal burning system, comprising
applying sorbent components comprising a halogen, calcium, silica, and alumina into the coal burning system; -
combusting the coal to produce ash and combustion gases; measuring a mercury level in the combustion gases; and adjusting the amount of halogen applied into the system based on the value of the mercury level. - View Dependent Claims (45, 46, 47, 48, 49, 50, 51)
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- 52. A coal ash made by a process comprising burning coal in the presence of added bromine, silica, and alumina.
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58. A process comprising
burning coal in the presence of 1-10% by weight of an added sorbent, the sorbent comprising about 30-75% by weight CaO, about 2-15% by alumina, about 5-20% by weight silica, about 1-10% by weight Fe2O3, and 0.1-5% by weight of alkali selected from Na2O and K2O; -
producing an ash by burning the coal; recovering the ash; and formulating a cementitious mixture comprising the ash. - View Dependent Claims (59, 60, 61)
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Specification