An Investigation into Transient Pressure Pulses for Gas-Solids Flow

Abstract

Pressure drop is very decisive and analytical parameter in the context of pneumatic conveying to know about flow characteristics and operating conditions for the reliable designing of fluidized dense phase pneumatic conveying systems. This study presents the results of ongoing investigation on transient pressure pulses using Shannon entropy technique. Pressure fluctuations (produced by gas-solid phase flow during fluidized dense phase conveying) were recorded by pressure transducers installed at strategic locations of pipeline. In the present work, two different powders have been conveyed i.e. fly ash (median particle diameter 45 µm, particle density 1950 kg/m3, loose-poured bulk density 950 kg/m3) and cement (median particle diameter 15 µm, particle density 3060 kg/m3, loose-poured bulk density 1070 kg/m3) through different pipelines (51 mm I.D. x 70 m long and 63 mm I.D. x 24 m long). The influences of superficial air velocity on Shannon entropy were also investigated. In this study, transient nature of pressure fluctuations was taken into consideration (instead of steady state behavior) for investigation to know more about flow characteristics. It was found that value of Shannon entropy and standard deviation increased along the straight sections of pipe for both products and for different pipelines. However, there is a decrease in value of Shannon entropy after the flow through bend. Different range of Shannon entropy value was obtained for fly ash and cement. Higher value of Shannon entropy was noticed corresponding to low velocities and high velocity region while minimum value of entropy was found corresponding to medium velocities. Effect of solid mass flow rate on Shannon entropy at constant value of air mass flow rate was also observed.