Solid particles in the pipeline (generally refers to the horizontal line) with the decrease of the average velocity of slurry distribution become more and more uneven, when flow velocity decreases to a certain value, appears at the bottom of the pipe fixed bed or sliding surface. Particles began to form the bed surface velocity is called sedimentation velocity. Due to the common carrier fluid is water, under the condition of normal pipe flow is usually a turbulent state, so the heterogeneous suspension under the deposition velocity of the flow pattern are almost turbulent state. It directly with the particle settling velocity and turbulence level in the system, so it is with the diameter of particles. Increase with the increase of the grain quality and solid content. The importance of the sedimentation velocity of pipe flow is obvious, it is the lower limit of the safe operation. If flow rate is lower than the sedimentation velocity will lead to form a solid particle bed surface, the friction loss with corresponding enlarged and often with pulsation, and even cause blockage. In order to ensure the normal order of the slurry in the pipeline flow, must make the minimum velocity over a given value, the speed is called the critical settling velocity. Generally the critical settling velocity is greater than the sedimentation velocity. |