Technique Of Sludge Liquefaction And Resistance In Sludge Pipeline-Transport

In the last few years, along with the booming of dredging business, pipeline-transport of sludge has gradually become one of the main modes of transport for dredged materials. But to transport the raw sludge always suffers large loss of head, and needs high energy consumption. Furthermore, it is easy to have pipeline jams. In order to obtain new technique to overcome these, two phases of experiment were carried out, which were presented in this thesis. The first phase was to experimentally investigate the effect of the sludge liquefaction induced by vibrations with high frequency and minute amplitude on fluid properties. The second phase was to investigate the sludge resistance in the slurry pipelines.Based on the liquefaction experiments on different kinds of sludge, it was found that the processed sludge possessed much higher mobility and lower viscosity, mainly represented in increasing of the velocity and reducing of the shear stress in pipelines. The denser the sludge, the more obvious its liquefied effect was. For the sludge with a sediment concentration of 23% (density 1.35g/cm3), the shear stress was reduced by 2.95% and the fluid velocity was increased 21.1% after liquefaction treatment, which indicated the sludge liquefaction technique has great significance to improve the transport efficiency and reduce the energy consumption.Another method for reducing the energy consumption during sludge transport is to reduce the resistance coefficient of the pipeline. The factors of the resistance such as sediment concentration, fluid types, pipeline shapes were theoretically analyzed. The coefficients reflecting distance resistance and local resistance were experimental measured, respectively. It was found the Moody Chart is not valid for high concentration transport. The local resistance coefficients lightly varied with sediment concentration in the pipeline. The resistance coefficients for the line-connectors and the 90-degree curve were as high as around 2.6 and 1.5, which were 9.3 and 2.6 times the values of clear water transport, respectively. A computational method for the pipeline design and several suggestions for engineering practice were proposed...