Measurement of bulk modulus of elasticity of dense pastes and its effects on flow rate in long pipeline

The amount of dense pastes, such as dewatered coal washing tailing, red mud, calcium carbide sludge and sewage sludge, is enormous and continues to grow rapidly. More engineering long pipelines with large diameter are employed to meet the urgent needs of their disposition, which results to serious reversed flow and strong vibration to the pipeline system. Both the problems have close relationship with the elastic parameters of the delivered paste. This paper presents a test undertaken for finding the bulk modulus of elasticity of the coal tailing. The test was undertaken on a long engineering pipeline for transporting coal slime paste based on the wave velocity method. By selecting suitable feature points in the pressure curves, the pressure wave propagation velocity in the coal slime was tested accurately. By the relationship between the elastic modulus of the paste and the wave velocity, the composite modulus of the coal slime and pipeline, and the true bulk modulus of the paste were both calculated. By resulting in serious reversed flow and reducing the effective piston stroke of the pump, the elastic recovery of the coal slime has an important effect on the actual flow rate. The variation characteristics of the pressure curves have proved that the measurement is an easy and practical method for finding the elastic modulus of dense pastes.