Research On Ejecting Air To Reduce And Prolong Transportation Distance In Tri-phase Flow Pipeline

In the working of cutter suction dredger, the slurry is transported by solid-liquid two-phase flow that is consisted of sand and water. This method cannot carry slurry too long, so some projects cannot be taken on. In order to prolong the distance of slurry transportation, the general transportation method is to add pumping station, which is expensive and inconvenient. So, people have managed to improve the efficiency of slurry transportation and reduce the energy. This research is to eject some compressed air into the dredging pipe to get tri-phase flow in the pipeline, and research the change about the pipe resistance, at the same time, obtain the more effect adding gas method and realize reduction friction and prolong the dredging distance.On the base of similarity theory of fluid system, the similarity numbers are analyzed, and the similarity relationship between the original model and the analogue model is researched, and much experiment has been carried out. In order to get experiment data, a computer measure system has been developed, which is mainly made up of host computer (PC) and extension computer (by SCM mainly).It is necessary to make model research on a test platform to know the radical law of tri-phase flow pipeline. In order to know the relationship between gas-content and pipeline's pressure drop, the thesis deduces the pressure drop calculating equations based on uniform flow pattern and separating flow pattern .The equations show that pressure drop is made up of three parts, that is, friction resistance effect, gas acceleration effect and the gravity effect. And the research has shown that the gas has little effect on pressure drop. In the horizontal pipeline, the resistance effect must be overmatched the acceleration effect. The author has studied some methods to eject gas into pipeline, at last, the water-air revolving spray-ejecting device is designed after some air-ejecting method are compared. Reasonable air-ejecting parameters have been induced according to processing and analyzing the experiment data using the device. In this thesis, the law of reduction friction and the law of prolong the transportation distance are discussed and the formula of prolong transportation distance rate hasalso been obtained.Based on the fruit of the model experiment, the application experiment is carried out on the 400m3/h cutter suction dredger. In order to know the probable influence that caused by compressed air and different slurry thickness, some experiments have been made. The experiment results indicate that it is effective to prolong transportation distance by tri-phase flow pipeline and the research is successful.