Reducing mercury emissions from the burning of coal
OwnerDouglas C. Comrieinventor
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Abstract
Processes and compositions are provided for decreasing emissions of mercury upon combustion of fuels such as coal. Various sorbent compositions are provided that contain components that reduce the level of mercury and/or sulfur emitted into the atmosphere upon burning of coal. In various embodiments, the sorbent compositions are added directly to the fuel before combustion; are added partially to the fuel before combustion and partially into the flue gas post combustion zone; or are added completely into the flue gas post combustion zone. In preferred embodiments, the sorbent compositions comprise a source of halogen and preferably a source of calcium. Among the halogens, iodine and bromine are preferred. In various embodiments, inorganic bromides make up a part of the sorbent compositions.
Claims36
A method for burning coal in a coal burning process with reduced levels of undesirable elements escaping into the environment, the method comprising
- adding a mercury sorbent composition comprising a halogen into the coal burning process;
- adding a sulfur sorbent composition comprising a calcium powder into the coal burning process;
- burning the coal to produce ash and combustion gases;
- measuring the level of sulfur in the combustion gases;
- measuring the level of mercury in the combustion gases;
- adjusting the amount of mercury sorbent composition added into the coal burning process based on the measured level of mercury;
- and
- adjusting the amount of sulfur sorbent composition added into the coal burning process based on the measured level of sulfur.
A method for reducing mercury emissions from a coal burning furnace, the method comprising:
- applying a sorbent composition onto coal, wherein the sorbent composition comprises a halogen compound and further comprises a nitrate compound, a nitrite compound, or a combination of a nitrate and nitrite compound;
- delivering the coal with the sorbent into the furnace of a coal burning plant;
- combusting the coal with the sorbent to produce ash and flue gases;
- measuring a level of mercury in the flue gases;
- and
- adjusting the amount of sorbent composition added, depending on the measured mercury level.
A method for reducing mercury emissions from a furnace in a coal burning facility, the method comprising:
- burning coal in the furnace to produce ash and flue gases;
- injecting a sorbent composition into the convective pathway downstream of the furnace where the flue gases have a temperature of 1500° F. to 2700° F.;
- measuring the level of mercury escaping from the facility;
- and
- adjusting the rate of injection of the sorbent composition depending on the measured mercury level,
- wherein the sorbent composition comprises a source of halogen and a source of calcium.
A method for reducing mercury emissions from a coal burning facility in a process comprising delivering coal to a furnace and combusting the coal in the furnace to produce ash and flue gases, the method comprising
- a) at least one of
- a1) adding a sorbent comprising an iodine compound onto the coal before it is delivered to the furnace;
- and
- a2) injecting a sorbent comprising an iodine compound into a convection path of the furnace where the temperature of the gases is 1500° F. to 2700° F.;
- b) measuring a mercury level in the flue gases;
- and
- c) adjusting the level of sorbent added in step a1) or step a2) depending on the measured mercury level in step b).
Dependencies are inferred from the claim text.