Patent ID: 7544250

Claim:
An apparatus for treating particulate material, comprising: a container having a process chamber for containing said particulate material and a container central duct separated from said process chamber, said container further having a longitudinal mid-axis; said process chamber being arranged around said longitudinal mid-axis of said container and being formed as an annular chamber, said process chamber further having a lower region and an upper region which is open; said container central duct forming a flow duct for process air flowing from an upper end of said container central duct to a lower end of said container central duct, and immediately opening into said lower region of said process chamber, and communicating with said upper open region of said process chamber so as to conduct said process air in at least one first operating state, by said container central duct widening circumferentially and opening towards said upper region of said process chamber; wherein, in a lower region of said container central duct, a fan is arranged immediately adjacent to a location where said container central duct opens into said lower region of said process chamber, wherein said fan has substantially vertical fan blades which extend to different radial extents; and wherein said process chamber is rotatably fixed relative to said container central duct about said container longitudinal mid-axis.