Rheological Properties of High Concentration Coal Slime

Area of Science:

• Fluid Mechanics
• Materials Science
• Chemical Engineering

Background:

• Concentrated coal slime is a viable fluid fuel transported via pipelines.
• Understanding coal slime's rheological properties (yield stress, viscoelasticity) and temperature dependence is crucial for efficient pipeline transport.
• Existing methods face challenges in measuring dynamic yield stress for highly viscous materials.

Purpose of the Study:

• To investigate the rheological properties and yield stress of coal slime at various temperatures.
• To explore the impact of temperature on coal slime's viscoelasticity.
• To determine the bulk modulus of coal slime using pressure wave velocity.

Main Methods:

• Rheological tests were performed on coal slime at different concentrations and temperatures.
• A novel method using residual pipeline pressure was developed to measure dynamic yield stress.
• Oscillatory shear tests were used to assess viscoelastic properties.
• Pressure wave velocity measurements determined the bulk modulus.

Main Results:

• Shear stress decreased with increasing temperature at high shear rates.
• Yield stress and low-shear stress increased with temperature.
• Coal slime demonstrated viscoelastic behavior, with shear elasticity rising with temperature.
• Pressure wave velocity remained constant and unaffected by temperature variations.

Conclusions:

• Temperature significantly influences coal slime's rheological behavior, affecting its suitability for pipeline transport.
• The proposed residual pressure method offers a viable alternative for dynamic yield stress measurement.
• Coal slime exhibits temperature-dependent viscoelasticity, a key factor for pipeline flow modeling.
• Bulk modulus is independent of temperature, simplifying certain transport calculations.