Nitrogenous sorbent for coal combustion
OwnerDouglas C Comrieinventor
Life of this patent
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Abstract
Sorbent compositions for coal contain nitrogenous components that reduce the level of mercury and/or sulfur emitted into the atmosphere upon combustion. The sorbent compositions are added directly to the fuel before combustion; directly into the fireball during combustion; are added to the fuel before combustion and into the flue gas post combustion zone; or are added completely into the flue gas post combustion zone, preferably where the flue gas temperature is at least 500° C. The sorbent compositions comprise a source of nitrate ions, a source of nitrite ions, or a combination of nitrate and nitrite sources. The sorbents are added as solids or as solutions in water. In various embodiments, the sorbent compositions further comprise a source of halogen such as bromide.
Claims27
A method for reducing the amount of mercury in combustion gases resulting from burning of mercury containing coal, comprising introducing a sorbent composition into the combustion gases in a zone where the temperature is greater than 500° C., wherein the sorbent composition comprises an effective amount of a nitrogenous component selected from the group consisting of a nitrate salt, a nitrite salt, and a combination of a nitrate salt and a nitrite salt.
A method for operating a fuel burning facility to reduce the amount of mercury released from the facility during combustion of a mercury containing fuel, the method comprising
- injecting a sorbent composition comprising a nitrate salt and/or a nitrite salt into flue gases where the temperature of the flue gas is in the range of 1500° F. to 2300° F.,
- monitoring the level of mercury in the flue gases downstream of the sorbent injection point, and
- adjusting the rate of sorbent addition to achieve capture of 90% or greater of the mercury in the mercury containing fuel before emission from the fuel burning facility.
A method for reducing sulfur and/or mercury emissions resulting from the combustion of coal in the furnace of a coal-burning system, comprising
- burning the coal in the presence of a nitrite salt and/or a nitrate salt,
- measuring the mercury level in flue gases resulting from the combustion,
- comparing the measured mercury level to a target level for emissions, and
- adjusting the level of addition of nitrite and/or nitrate salt depending on the measured mercury level.
A method for burning coal with decreased emissions of mercury, comprising
- combusting coal in a coal burning system to produce flue gases and ash;
- adding calcium nitrate and calcium nitrite into the coal burning system during combustion,
- measuring the level of mercury in the flue gases, and
- adjusting the amount of calcium nitrate and calcium nitrite added into the coal burning system depending on the measured level of mercury.
A method of burning carbonaceous mercury containing fuel in a fuel burning facility to reduce the amount of mercury released from the facility, the method comprising
- combusting the fuel in the fuel burning system;
- adding calcium nitrate and calcium nitrite into the fuel burning system during combustion;
- measuring a level of mercury in the flue gases resulting from the combustion;
- and
- adjusting the amount of calcium nitrite and calcium nitrate added into the coal burning system depending on the level of measured mercury.
Dependencies are inferred from the claim text.