关键词: 搅拌, 剪切率, 计算, 模拟, 原油, 管道输送, 非牛顿流体

Abstract: The existing Metzner-Otto equation for stirring shear rate estimation is only suitable for calculating the average shear rate around the impeller in the laminar flow of some impeller-vessel systems and cannot meet the requirement of shear simulation for the process of oil pipelining.On the basis of the relationship between the energy dissipation rate in the fluid flow and the shear rate,an approach is presented to estimate the whole-vessel average shear rate in a stirred vessel by using the shaft power of the stirrer. Some equations of shear rate estimation for Newtonian fluid and the power law fluid were derived.Taking a small stirring system used for laboratory test as an example, an empirical model to correlate the whole-vessel average shear rate and the stirring speed,fluid volume in the vessel, consistency coefficient and flow behavior index of the power law fluid was developed by using the present approach.The shear rates estimated by the empirical model are in good agreement with those calculated according to the measured torque of the shaft.This approach is available for different types of impeller and flow regime,and can also be applied to the non-Newtonian fluids favorable to other rheological models.

Key words: stirred vessel, shear rate, estimation, simulation, crude oil, pipelining, non-Newtonian fluid