Tube coolers for rotary kilns

A rotary heat exchange apparatus for achieving heat exchange between a gas and solid particulate material comprising:

• a tubular vessel mounted for rotation about an axis and having peripheral walls, an inlet and an outlet for solid particulate material whereby solid particulate material moves through the vessel from the inlet to the outlet for solid particulate material, an inlet for gas and an outlet for gas whereby gas flows through the vessel from the inlet to the outlet for gas;
• and
• a plurality of circumferentially spaced apart heat exchange fins mounted on the inside of the peripheral walls of the tubular vessel;
• said peripheral walls of said tubular vessel being substantially solid in the region of said heat exchange fins around the circumference of the tubular vessel;
• each of said heat exchange fins being mounted to form an acute angle between the trailing surface of the fin in the direction of rotation of the vessel and the peripheral wall of the vessel which permits contact of the solid particulate material with both the leading and trailing surfaces of the fin near the base of the fin while substantially preventing lifting of the solid particulate material into the gas which flows through the vessel.

Apparatus for cooling solid particulate material thermally treated in a rotary kiln including a plurality of elongated cylinders adapted to be mounted on a rotary kiln for rotation with said rotary kiln about the axis of the kiln, each of said cylinders having an inlet at one end for receiving hot solid particulate material discharged from said kiln;

• an outlet at the other end for discharging cooled solid particulate material from the cylinder;
• an inlet as said other end of the cylinder for supplying cooling air to the cylinder whereby the cooling air passes through the cylinder, the hot solid particulate material is cooled and the cooling air is supplied to the kiln as preheated combustion air;
• apparatus for improving the heat exchange within the cylinder comprising;
• a helical conveyor mounted within each of said cylinders for advancing material from the inlet for solid particulate material to the outlet for solid particulate material;
• and
• a plurality of circumferentially spaced apart fins mounted in each of said cylinders between at least some of the adjacent flights of said conveyor.