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TECHN I CAL REPORT September 1, 1987 through August 31, 1988

Project Title: CHARACTERIZATION, STABILITY AND RHEOLOGY OF COAL-WATER SLURRIES

Principal Investigator: Raffi M. Turian, UIC Other Investigators: Dr. F.-L. Hsu, UIC

Mr. J. F. At tal, U I C Mr. O. -J. Sung, U I C Mr. R.K. Allendorfer, UIC Mr. Y. -H. Kim, U I C Mr. G. B. Sa 1 i ba, U I C

Project Monitor: Dr. John L. Lytle, CRSC

ABSTRACT

This report presents the results of studies on the characterization and rheology of coal-water slurries (CWS) made up of four different coals. The report covers the 12-month project per10d from 9/1/87 to 8/31/88. The main results presented in this report include: coal analyses, particle characterization; suspension characterization; measurements of the yield stress of CWM as a function of sol ids concentration and their correlation; measurements of the shear stress/shear rate/concentration dependence of CWM for different coals and their correlation; measurement and correlation of the heat capacities and thermal conductivities of CWMj and studies on sedimentation and sediment property characterization for CWM. The shear stress/shear rate data cover the shear rate range between 10- 1 (l/sec) and 105 (l/sec), and were taken mainly using a capillary tube viscometer.:A significant characteristic of most of the capillary shear stress/shear rate measurements was the existence of marked wall slip effects, which required correction; a tedious procedure. The corrected flow curves were generally found to exhibit shear-thinning behavior over the lower shear rate range, and to approach limiting Newtonian behavior at high shear, characterized by an asymptotic high-shear viscosity ~~. Slurry yield stresses were measured directly using the vane geometry and were correlated with concentration using the maximum packing volume fraction as a parameter. These results are useful in assessing the stability of the CWS at rest, and in predicting friction losses for laminar and turbulent flow through straight pipe and through pipel ine bends, fittings, valves and flow metering devices and also in estimating laminar-turbulent transition. The data at high shear rates are also useful in analysis and design of spray and atomization processes involving CWS. The heat capaciti~s of the coal powders and of the coal­~at~rmixtures were found to fol low a simple additive group contribution model. The thermal conductivity data on CWS were used to develop a correlation for effective mixture conductivity based on volume. fraction of solids and on ratio of solids to liquid

-____ conductivities. In addition, these d_a_ta_w_er:.e_used-to-deve-lop-a--------------------------proceaure for estimating the sol ids thermal conductivity of the

granular coal.