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US 4,059,392 AGranted
Calcination of pulverous material
AssigneeF. L. Smidth & Co.
InventorJorn Touborg
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AssigneeF. L. Smidth & Co.
InventorJorn Touborg
Estimating the term…
A method of heat treating a preheated, pulverous, raw material consisting of or containing lime, such as cement raw meal. By mixing at least part of the preheated raw material intimately with a fuel capable of carrying out at least a partial calcination, a suspension of raw material in a combustible gas is provided. Upon providing a flow of oxygen-containing gas in contacting relation with the suspension of gas/material, at least a partial calcination takes place according to an endothermic process in which calcium carbonate is dissociated into calcium oxide and carbon dioxide. A finishing calcination and/or other heat treatment may follow the calcination process. When the raw material is cement raw meal, the aforesaid finishing heat treatment following the calcination is a sintering by which cement clinker is produced according to an exothermic process. A unique calcination plant is disclosed for at least partially calcining a preheated pulverous, raw material according to the present method wherein by a supply of heat before the material is subjected to a finishing calcination and/or other heat treatment, if any, at least a partial calcination may be performed approximately isothermically and at a relatively low temperature.
A calcination plant for treating a preheated, pulverous raw material consisting entirely of, or at least containing a portion of, lime comprising a conduit, means for passing a flow of oxygen-containing gas upwardly through said conduit, a mixing chamber positioned adjacent said conduit defining a mixing zone for mixing preheated raw material and a fuel, means for separately and continuously feeding fuel and preheated raw material to said mixing zone for accumulating and substantially and uniformly intimately mixing said fuel and preheated raw material prior to calcination to provide a suspension of a fuel gas and raw material particles, said mixing zone being positioned adjacent said conduit and communicating therewith such that the suspension of fuel gas and raw material particles are drawn from said mixing zone into said conduit by said flow of oxygen-containing gas so as to contact the oxygen-containing gas flowing up through said conduit to become entrained by said oxygen-containing gas to provide at least a partial substantially isothermal calcination of said raw material particles by the contact of the uniformly mixed preheated raw material and fuel with the oxygen-containing gas.
An apparatus for calcining preheated, pulverous raw material consisting of, or at least containing a portion of, lime comprising a pipe having its upper end portion connected to a particle/gas separator, a fan for directing a flow of oxygen-containing gas through said conduit, a mixing chamber positioned adjacent said pipe and defining a mixing zone having wall portions extending generally upwardly and adapted to accumulate preheated raw material and a fuel so as to permit intimate mixing thereof, means for separately and continuously feeding fuel and preheated raw material to said mixing zone in relative directions so as to accumulate and substantially uniformly intimately mix said fuel and preheated raw material prior to calcination to provide a suspension of a fuel gas and preheated raw material particles, said mixing chamber opening into said pipe so as to communicate said mixing zone therewith such that the suspension of fuel gas and raw material particles are drawn from said mixing zone and entrained by said oxygen-containing gas to thereby provide at least a partial, substantially isothermal and uniform calcination of said raw material particles by the contact of the uniformly mixed preheated raw material and fuel with said oxygen-containing gas.
An apparatus for calcining preheated, pulverous raw material consisting of, or at least containing a portion of, lime comprising a chamber having its upper end portion connected to a particle/gas separator, a pipe communicating with the lower end portion of said chamber and a fan for directing a flow of oxygen-containing gas through said calcination chamber, the lower portion of said calcination chamber surrounding the upper end portion of said oxygen-containing gas pipe defining an annular mixing zone having wall portions adapted to accumulate and mix preheated raw material and a fuel, means for continuously feeding preheated raw material to said mixing zone, means for feeding fuel to said mixing zone so as to accumulate and substantially uniformly intimately mix said fuel and preheated raw material prior to calcination to provide a suspension of fuel gas and preheated raw material particles, said mixing zone being positioned adjacent to said oxygen-containing gas pipe and in such relation that the suspension of fuel gas and raw material particles are drawn from said annular mixing zone and entrained by said oxygen-containing gas to thereby provide at least a partial, substantially isothermal and uniform calcination of said raw material particles by the contact of the uniformly mixed preheated raw material and fuel with said oxygen-containing gas.
An apparatus for calcining preheated, pulverous raw material consisting of, or at least containing a portion of, lime comprising a chamber having its upper end portion connected to a particle/gas separator, a pipe communicating with the lower end portion of said chamber and a fan for directing a flow of oxygen-containing gas through said calcination chamber, at least two conduits communicating with the lower end portion of said calcination-chamber to direct intimately mixed preheated raw material and fuel in a downward direction into said calcination chamber, said conduits being adapted to accumulate and mix preheated raw material and a fuel therein prior to being fed to said calcination chamber for calcination, said conduits further being positioned sufficiently adjacent the upper end portion of said oxygen-containing gas pipe such that the intimately mixed preheated raw material and fuel are drawn into the upward flow of oxygen-containing gas so as to be entrained and contacted by said oxygen-containing gas to provide at least a partial substantially isothermal calcination of said raw material particles by the contact of uniformly mixed preheated raw material and fuel with the oxygen-containing gas.
An apparatus for calcining preheated pulverous raw material consisting of, or at least containing a portion of, lime comprising a calcination chamber having its upper end portion connected to a particle/gas separator and a lower end portion connected to a particle/gas separator and a lower end portion having inwardly sloping wall portions, a pipe communicating with the lower end portion of said chamber for directing a flow of oxygen-containing gas into and through said calcination chamber, said pipe being telescopically retractable inwardly and outwardly with respect to said calcination chamber to provide adjustability in the portion of the pipe extending into the calcination chamber and defining a variable weir and annular mixing zone with said sloping lower wall portions of said calcination chamber, at least one conduit communicating with the lower end portion of said calcination chamber to direct preheated raw material therein in a downward direction into said annular mixing zone to provide substantially and intimate mixing of said preheated raw material and fuel in said annular mixing zone such that oxygen-containing gas being passed upwardly through said adjustably positioned pipe and into said calcination chamber entrains and contacts the intimately mixed preheated raw material particles and fuel overflowing the weir to provide at least a partial substantial isothermal calcination of said raw material particles by the contact of the uniformly mixed preheated raw material and fuel with the oxygen-containing gas.
Dependencies are inferred from the claim text.