| With the development of drilling technology, deep well, ultra deep well and horizontal well drilling has been very common, the down-hole problems become more complex, and it put forward higher requirements on drilling fluid properties. The drilling fluid centrifuge is an important equipment of solids control system, it plays a very important role in the process of recovery weighting agent and removal of harmful solid phases. However, because of the complexity of the drilling fluid properties and the dynamic changes of the drilling fluid parameters characteristic in the drilling process, it has been exist many problems, such as small amount, uneven distribution of materials, vibration, noise and so on. Thus not only affected the separation efficiency of the centrifuge, but also caused serious security risks from the large vibration. So, this paper based on the problems of slowly feed diffusion and uneven distribution to designed and investigated centrifuge feed accelerator through the methods of theoretical research, design improvement and numerical simulation, to designed the efficient large capacity centrifuge which can cause the materials rapidly settling and provided valuable references for design drilling fluid centrifuge.The research work of this paper is mainly embodied in the following respects:(1) The relevant information and on-site applications of drilling fluid centrifuge were investigated completely, and the application status at home and abroad, problems and develop trends were comprehended. The separation theory of drilling fluid centrifuge were studied, and the necessity for the feed accelerator design was confirmed by analysis and comparison of flow field theory between the accelerated centrifuge and conventional centrifuge(2) Based on the design theories of horizontal spiral centrifuge, a large amount of processing design to the type of LW450-1000 was made, the feed device and feed camber were improvement designed, and the feed accelerator blades were preliminary designed, the feed chamber flow field with the accelerator or not were contrasted, and then the superiority of the feed chamber with accelerator blades in the acceleration and diffusion of materials was confirmed.(3) The influence of accelerated camber flow field from the parameters of entry diameter, exit diameter, blade form, number of leaves, feeding port and other factors were analyzed, and parameters optimization were made. The feed inlet on the screw conveyor was corresponding improved and designed, and comparative analysis of multi-parameter of variable angle helix, involute and controllable angle curves were made by referenced the design theories and methods of centrifugal pump blades, and then a group of superior blades scheme was defined.(4) The flow field models of conventional drilling fluid centrifuge without accelerate blades and the new type accelerate drilling fluid centrifuge were built. Based on the theory of fluid dynamics, CFD technology was used to made numerical simulation of the flow field in the bowl about the two centrifuges, then the regular of material diffusion, distribution characteristics and separation characteristics were contrasted, and the performance of the new centrifuge were verified. Besides, the flow field of the accelerated centrifuge under two kinds of drilling fluid were simulated, one is the conventional unweighted drilling fluid and the other is the drilling fluid with tiny drilling cuttings, then the favorable adaptability of the accelerated centrifuge to different materials were verified.(5) The static analysis of the screw conveyor and accelerated blades in the new type of drilling fluid centrifuge were made based on the theory of one-way coupling. And the strength of the new type of centrifuge were verified. |
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