Counterflow rotary cooler

A counterflow rotary cooler for cooling solid granular material product, the cooler comprising:

• an elongated rotary vessel having a vessel first end and a vessel second end, the vessel first end being at a lower elevation relative to the vessel second end;
• a cooling fluid inlet located proximate said vessel first end;
• a cooling fluid outlet located proximate said vessel first end;
• an outer tube having a first outer tube end and a second outer tube end and extending substantially from said vessel first end to said vessel second end inside said elongated rotary vessel, said outer tube being in fluid communication with said cooling fluid inlet;
• an inner tube nested inside said outer tube and having a first inner tube end and a second inner tube end extending substantially from said vessel first end to said vessel second end but terminating short of the outer tube second end, whereby said inner tube and said outer tube form a nested tube set and define an annulus between said inner tube and said outer tube through which cooling fluid flows;
• and
• a cap enclosing said outer tube second end of said nested tube set, such that when cooling fluid flows into said fluid inlet, it flows through said annulus to said outer tube second end and is directed by said cap into said inner tube at said inner tube second end and flows from said vessel second end to said vessel first end and then out said cooling fluid outlet proximate to said vessel first end;
• an auger disposed proximate to said vessel second end for introducing solid product into said vessel at said vessel second end;
• and
• a product outlet at said vessel first end, so that when product enters the vessel through said auger, it flows to said vessel first end and out said product outlet.