Characteristics Of Industrial-scale Dense-phase Pneumatic Conveying System For Pulverized Coal

Based on the application of dense-phase pneumatic conveying system in pressured entrained flow gasification of pulverized coal, an industrial-scale horizontal (50mm I.D.) dense phase pneumatic conveying system in laboratory was investigated. This research also focused on two large-scale conveying systems located in a pilot plant (42mm I.D.) and Shell gasification installation (54mm I.D.). Furthermore, the key units were investigated including a new type feeder vessel and solid flowrate regulating valves.Flow patterns of gas-solid flow in horizontal pipe were investigated qualitatively and quantificationally, using solid flowmeter, electrical capacitance tomography and high-speed video camera. The flows in the experimental range were classified into four regimes:stratified flow, dune flow, moving bed flow and slug flow. Using probability density function and power spectral density function to analyze the pressure signals, pressure fluctuations were found well correlated with flow patterns. The relative stability characteristics of under different operating conditions showed that the critical velocity between stable and unstable conveying was smaller than minimum pressure drop velocity due to the transition of flow patterns. Based on the experimental data obtained from laboratary, pilot plant and Shell installation, a flexible empirical model of horizontal pipe pressure drop was built with high precision of±20%.Transport capacity, relatively stability and energy consumption were found promoted by the new type feeder vessel, comparing with the line source aeration feeder vessle. Through analysis of domestic and imported regulating valves, both had their own advantage and disadvantage and showed good application prospect.