Leroy Dockter

Date of Award


Document Type


Degree Name

Master of Science (MS)


Chemical Engineering


The use of cooling coils or pipes to control the reaction zone temperatures when oxidizing lignite in a fixed bed was studied. The experimental procedures involved passing heated air through a bed of lignite to initiate spontaneous heating and then removing the heat generated using a water cooled coil. Variables investigated included the lignite moisture content, prior oxidation history, and lignite source.

Spontaneous heating was initiated in lignite from three different mines, and at initial moisture contents from bed moisture down to 10 percent by heating the lignite to 250-260 °F while passing air slowly through the bed. At moisture contents below 10 percent or after severe oxidation the temperature necessary to initiate spontaneous heating rose to over 300 °F.

The low thermal conductivity of the lignite bed was found to prevent adequate heat removal from the bed to permit satisfactory control of the oxidation of lignite. An equation describing the temperature distribution in the lignite between cooling pipes embedded in the oxidizing lignite was developed.