Reducing mercury emissions from the burning of coal
OwnerDouglas C Comrieinventor
Life of this patent
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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.
Claims26
A process for burning coal to reduce the amount of mercury released into the atmosphere comprising
- applying a liquid sorbent composition comprising calcium bromide onto the coal;
- applying a powder composition comprising aluminosilicate clay and one or more components selected from portland cement, cement kiln dust, lime kiln dust, calcium oxide, calcium hydroxide, and calcium carbonate onto the coal;
- delivering the coal with the applied sorbents into a coal burning furnace;
- combusting the coal containing the sorbent in the coal burning furnace to produce ash and combustion gases;
- measuring a mercury level in the combustion gases;
- and
- adjusting the amount of liquid sorbent composition applied to the coal based on the value of the mercury level.
A system for burning coal with reduced levels of mercury released outside the system comprising
- a sorbent composition comprising calcium bromide, aluminosilicate clay, and one or more components selected from Portland cement, cement kiln dust, lime kiln dust, calcium oxide, calcium hydroxide, and calcium carbonate;
- a coal burning furnace comprising a burning chamber, a convection path for combustion gases leading from the burning chamber to an exit outside the convection path, and a particle collection device disposed in the convection path;
- an apparatus for delivering coal to the furnace for combustion;
- an apparatus disposed in the convection path for measuring the level of mercury in the convection path;
- a sorbent delivery apparatus disposed to deliver the sorbent composition onto the coal before delivery of the coal into the furnace;
- and
- a controller disposed to receive an output signal from the mercury measuring apparatus, and operationally connected to the sorbent delivery apparatus to adjust the delivery of the sorbent based upon the value of the output signal.
A process for burning coal with reduced levels of undesirable elements escaping into the environment comprising
- adding a mercury sorbent composition comprising a halogen into the coal burning process;
- adding a sulfur sorbent composition comprising a calcium powder and an aluminosilicate clay into the coal burning process;
- burning the coal to produce ash and combustion gases;
- measuring the level of mercury in the combustion gases;
- and
- adjusting the amount of halogen added to the coal based on the level of mercury.
A method for reducing the level of mercury released into the atmosphere upon combustion of coal containing mercury in a coal burning system comprising a furnace and a convective pathway for combustion gases, the method comprising
- adding a mercury sorbent and a sulfur sorbent onto pulverized coal;
- burning the coal in the furnace;
- burning the coal along with the sorbents to produce combustion gases and ash;
- measuring a mercury level in the combustion gases;
- and
- adjusting the amount of mercury sorbent added depending on the measured mercury level,
- wherein the mercury sorbent comprises a halogen and the sulfur sorbent comprises a calcium compound and an aluminosilicate clay.
A process for burning coal to reduce the amount of mercury released into the atmosphere comprising
- applying a sorbent composition comprising calcium bromide and further comprising a nitrite compound or a nitrate compound onto the coal;
- delivering the coal into a coal burning furnace;
- combusting the coal containing the sorbent in the coal burning furnace to produce ash and combustion gases;
- measuring a mercury level in the combustion gases;
- and
- adjusting the amount of sorbent composition applied to the coal based on the value of the mercury level.
Dependencies are inferred from the claim text.