Method and apparatus for calcining limestone using coal combustion for heating
AssigneeWestinghouse Electric Corp.
InventorsJames A. Dilmore, Suh Y. Lee, William E. Young, Wesley M. Rohrer, Jr.
Life of this patent
Estimating the term…
Abstract
A method and apparatus for calcining limestone to produce lime wherein coal is combusted to provide heat for the calcination. The coal is combusted in a two stage combustion unit, with at least seventy-five percent of the slag formed by the coal combustion removed from the first stage of the combustion unit. Residual gases and fuel are further combusted in the second stage of the two stage combustor, with hot combustion gases therefrom, having the molten slag removed, fed directly to the calcining chamber of a rotary lime kiln. The coal may be carbonized to form a char and a fuel gas for use in the two stage combustor.
Claims18
A method of firing a lime kiln having a calcining chamber in rotary vessel with limestone charged to one end thereof and hot gases applied to the other end, with a hot gas stream passing therethrough countercurrent to the flow of limestone to produce lime, such that the formation of a slag ring in said rotary vessel is retarded or eliminated comprising:
- providing a two stage combustion unit for producing said hot gases;
- charging a solid carbonaceous fuel and air in the first stage of said two stage combustion unit and combusting the fuel, with less than a stoichiometric amount of oxygen to produce substantially complete combustion of said solid carbonaceous fuel, to provide hot combustion gases and molten slag in said first stage;
- removing at least 75 percent of said molten slag from said hot combustion gases and discharging said slag from said first stage of the two stage combustion unit;
- passing said hot combustion gases and any residual solid carbonaceous fuel into the second stage of said two stage combustion unit;
- charging air to said second stage to effect combustion of said hot combustion gases and any residual solid carbonaceous fuel in said second stage of the two stage combustion unit, to product a hot gas stream;
- and
- directly charging said hot gas stream into said calcining chamber for countercurrent flow therethrough relative to the flow of limestone therein, and exhaustion therefrom.
In a lime kiln having a calcining chamber in a rotary vessel and means for charging limestone at one end thereof and removing lime from the other end thereof, with means for charging a hot gas stream through the calcining chamber thereof countercurrent to the flow of limestone and lime therein, wherein coal is combusted with air to produce said hot gas stream which contains molten slag, the improvement comprising;
- a two stage combustion unit for the combustion of said coal including means in the first stage of said two stage combustion unit for the removal of at least 75 percent of molten slag therefrom prior to introduction of said hot gas stream into said calcining chamber.
Dependencies are inferred from the claim text.