AUSTRALIAN OIL SHALE THERMAL PROPERTIES DURING PROCESSING
Adam J. Berkovich
Chemical Technology and Engineering Group
Dept. of Chemistry, Materials and Forensic Science
University of Technology, Sydney, Australia
Thursday, September 17, 1998 3:30 pm
Ben Bandy Conference Center
Center for Applied Energy Research
Australia's increasing reliance on fossil fuels has provided the impetus for research into the exploitation of its oil shale reserves. In Australia, the proposed oil shale processing method is based upon rotary kiln technology. The continued development of the technology for oil shale processing has revealed the need for a process model based upon oil shale thermal behavior. Therefore a comprehensive database of oil shale component thermodynamic properties is required for the development of an adequate thermodynamic process model.
The aim of this work was to obtain heat capacity and enthalpy of reaction data for all the thermal reactions occurring in the drying and retorting of typical Australian Tertiary oil shales. In a process that is dominated by thermal reactions and heat transfer, a knowledge of these data is important, as they need to be incorporated into chemical engineering models to enable the performance of various processing configurations to be assessed, in order to unlock the extensive oil shale resources of Queensland.
A novel approach has been taken for determination of oil shale component thermodynamic properties. This approach is based upon physical and chemical separation of the unique components in the oil shale followed by analysis of these components using modulated differential scanning calorimetry (MDSC). MDSC is a new calorimetric technique capable of measuring heat capacity and reaction heats in a single experiment. The ability to measure heat capacity during thermal reactions is unique to this technique and this has important consequences for use in future process models.
For the first time, heat capacity data have been measured for samples of pyrolysed kerogen. The data are similar to those estimated from model compound experiments but represent a considerable improvement over estimates made previously based on heat capacities of coked coal.
With the thermal data either obtained from the literature or measured, and the concentrations of the oil shale components known, an oil shale thermodynamic database was developed. This database model was constructed in a spreadsheet environment to allow the calculation of the total enthalpy requirements for drying and retorting of a typical Australian Tertiary oil shale between two temperatures of interest. This tool is of considerable practical importance in assessing the thermal requirements for processing Australian Tertiary oil shales.