Rotary kiln with end and intermediate discharge

Claim 2

In a rotary kiln having a cylindrical shell mounted for rotation about a central axis therethrough, a material feed hood enclosing one end of the shell, a firing hood with a burner and combustion air inlet means enclosing the other end of the shell and operative to burn fuel therein and establish a temperature gradient along the axis of the shell from the firing hood to the feed hood which provides a calcining zone, a preburning zone and a drying zone, and an intermediate discharge means located in the kiln shell to discharge dry material from the kiln that has passed the end of the drying zone adjacent the preheating zone, said intermediate discharge means comprising: material discharge passage means through the shell of the kiln; a conduit connected to the passage means and encircling the outer periphery of the shell for at least one complete turn around the shell, to provide a discharge therethrough of dry material from the kiln and maintain at least one conduit closing portion of such material in the encircling conduit at all times to close off the material discharging means from the atmosphere surrounding the kiln; an intermediate duct between the passage means through the kiln shell and the encircling conduit; and adjustable valve means mounted in the intermediate duct between the passage means and the encircling conduit.

Claim 3

In a rotary kiln having a cylindrical shell mounted for rotation about a central axis therethrough, a material feed hood enclosing one end of the shell, a firing hood with a burner and combustion air inlet means enclosing the other end of the shell and operative to burn fuel therein and establish a temperature gradient along the axis of the shell from the firing hood to the feed hood which provides a calcining zone, a preburning zone and a drying zone, and an intermediate discharge means located in the kiln shell to discharge dry material from the kiln that has passed the end of the drying zone adjacent the preheating zone, said intermediate discharge means comprising: material discharge passage means through the shell of the kiln; a conduit connected to the passage means and encircling the outer periphery of the shell for at least one complete turn around the shell, to provide a discharge therethrough of dry material from the kiln and maintain at least one conduit-closing portion of such material in the encircling conduit at all times to close off the material-discharging means from the atmosphere surrounding the kiln; and the material discharge passage means comprising a plurality of radially extending passages in a common radial plane, an intermediate duct connected to and projecting outwardly of each of the passages, and the encircling conduit being connected to each of the intermediate ducts.

Claim 4

In a rotary kiln having a cylindrical shell mounted for rotation about a central axis therethrough, a material feed hood enclosing one end of the shell, a firing hood with a burner and combustion air inlet means enclosing the other end of the shell and operative to burn fuel therein and establish a temperature gradient along the axis of the shell from the firing hood to the feed hood which provides a calcining zone, a preburning zone and a drying zone, and an intermediate discharge means located in the kiln shell to discharge dry material from the kiln that has passed the end of the drying zone adjacent the preheating zone, said intermediate discharge means comprising: material discharge passage means through the shell of the kiln; a conduit connected to the passage means and encircling the outer periphery of the shell for at least one complete turn around the shell, to provide a discharge therethrough of dry material from the kiln and maintain at least one conduit-closing portion of such material in the encircling conduit at all times to close off the material-discharging means from the atmosphere surrounding the kiln; and the material discharge passage means comprising a plurality of radially extending passages in a common radial plane, an intermediate duct connected to and projecting outwardly of each of the passages, and the encircling conduit being connected to each of the intermediate ducts.

Claim 5

In a rotary kiln according to claim 2, an adjustable valve in each of the intermediate ducts for controlling the flow of dry material from the radially extending passages, through the intermediate ducts and into the encircling conduit for discharge therefrom.

Claim 6

In a rotary kiln according to claim 3, said encircling conduit making at least one and one-quarter turns around the shell.

Claim 7

In a rotary kiln according to claim 3 each said adjustable valve is a slide valve arranged to move in a plain pErpendicular to a central axis through the duct in which each such valve is provided.