SBIR-STTR Award

The processes and equipment for handling solids andslurries are quite inefficient when compared with equipment thathandles liquids and gases. This is largely because designers donot clearly understand the behavior of granular solids and slurriessuch as coal-water slurries. In Phase I of this project, atorsional rheometer that can be used to measure the materialproperties of granular solids such as coal and coal-water slurriesis being designed. The rheometer consists of two parallel disksmounted on air bearings that are rotated by motors about a commonaxis. A strain gauge is mounted along the z direction. A strainrosette is mounted on the bottom disk-that is, strain gauges aremounted along the x and y directions, and one is mounted at a 45'angle. This will help determine the tractions and moments on thebottom plate that in turn will help detect the material properties(such as cohesion, adhesion, viscosity, etc.) of the granularsolid. The disks must be rough so that the granular materials canadhere to them. In Phase II, it is planned to fabricate such arbeometer with which to determine the material modulicharacterizing granular materials and coal slurries.Anticipated Results/Potential Commercial Applications as described by the awardee:In Phase III, it is expected that commercialintroduction of the torsional rheometer would begin, so that itbecomes possible for industry to measure the properties of coal andof coal slurries. Moreover, measuring and understanding thesurface properties of coal would assist in the design of bins andhoppers, transportation systems for coal and coal-water slurries,and fluidized bed combustion.

Solids and slurries handling processes and equipment are quiteinefficient when compared to equipment that handle liquids andgases. This is primarily due to a lack of a clear understandingof the behavior of granular materials and slurries. In Phase 1,a torsional rheometer was designed. The use of this rheometerwill lead to a better characterization of the properties ofgranular materials and slurries. In Phase II, this rheometer willbe fabricated and calibrated. The rheometer has a cup and plateassembly between which the material is placed. The cup is fixedwhile the plate is capable of rotating and/or oscillatingtorsionally about their common axis. The cup and plate areremovable. The unique rheometer design also allows the use ofeither sintered porous disks or impervious disks for the cup andplate. The sintered porous disk design allows the fluidization ofgranular materials, and the impervious disk design allows themeasurement of the properties of slurries. A dynamometer on theshaft of the bottom CUP assembly measures the three dynamiccomponents and the dynamic reaction torque experienced by thebottom cup. A rotating dynamometer mounted on the shaft of thetop plate also provides the three dynamic force components andthe dynamic torque. The spacing between the plates and the motionof the motor is also controlled by the computer. The data fromthe top and bottom dynamometer are correlated to determine thematerial moduli, using a computer data acquisition system andsoftware. A rheometer will be manufactured that can measure theproperties of granular materials, using a computer dataacquisition system and software.Anticipated Results/Potential Commercial Applications as described by the awardee:The use of this rheometer will resultin better designs for solids handling equipment like bins, silos,hoppers, chutes, hydrocyclones, agricultural grain dryers andcombustors, and in the transportation of solids and fluidizedbeds. Since the inefficient performance of these various deviceshas contributed to inefficient plants and sometimes theirfailure, better Theological characterization of slurries shouldlead to tremendous savings. It should also lead to significantsavings in other industries involved in surface finishing, andmake possible measurement of all the material moduli of blood,needed for design of the artificial heart.