Experimental investigation and analysis of pressure fluctuations in pneumatic conveying systems with fine bulk solids

When reducing the conveying gas velocity during the pneumatic transport of fine-grained bulk materials, the process goes through a wide variety of flow modes. Along this reduction in velocity, there are pressure fluctuations of varying degrees, the so-called pressure pulsations. These have been intensively studied over the past 30 years, mainly about the associated flow mode. In this work, the pressure pulsation is systematically investigated. For this purpose, conveying tests were carried out with cement as bulk solid and varying solid loadings and air mass flows, starting with the dilute mode, and ending with pipe blockage. The pressures were sampled and evaluated. Criteria for assessing pressure pulsations are applied. These are systematically related to the solid loading ratio (SLR), the Froude number (gas velocity) and the Euler number related to the pressure drop, based on a dimensional analysis. The resulting dependencies are evaluated qualitatively and quantitatively. • Analysis methods for pulsations of horizontal conveying lines. • Flow mode influence on pressure pulsations. • Influence of turbulence on pressure pulsations. • Shannon Entropy, Hurst Exponent and Transient data of pulsations.