Research On Multi-motor Coordinated Control Strategy Of Solid-liquid Separator

In recent years,with the continuous development of petroleum exploration and drilling technology,higher requirements have been put forward for the recovery quality of drilling fluid.Therefore,it is necessary to improve the ability of drilling solid control system,especially the screening efficiency,processing capacity,energy saving and noise reduction ability of shale shaker.Shale shaker is an essential first stage screening equipment in drilling solid control equipment.It plays an important role in the task of removing the solid phase of drilling fluid It's working ability affects the quality of the whole solid control system directly.The research object of this paper is a new type of shale shaker with cylindrical screen,it is expected to realize the functions of sand(mud)remover,centrifuge and other equipment due to the combination of drum,it even can be applied in a wider field of solid-liquid separation,so it is called as solid-liquid separator.When the solid-liquid separator is working,the screen not only moves with the screen box elliptically,but also rotates around its axis.Changing the speed of the exciting motor and the rotating drum is the main method to improve the performance of the solid-liquid separator.Solid-liquid separator achieved elliptic vibration by two motor dragging vibration exciter to move,and the drum is dragging for circular movement by two motor.The purpose of this paper is to coordinate the speed of four motors to make the performance of processing capacity,processing efficiency(migration of solid phase),processing effect and power consumption of the solid-liquid separator be optimal performance.The following aspects of research are mainly carried out.(1)On the basis of the two-axis translational elliptical shale shaker,the dynamic equation was established and the working principle of the solid-liquid separator was analyzed,to obtain the motion trajectory of each point on the cylinder screen.(2)According to Newton's law of mechanics,the mechanical model of single particle on drum-type sieve net is established,the throwing capacity of solid-liquid separator is analyzed,the mathematical expression of throwing index is given,and the moving velocity of single particle along the axial direction of sieve net is calculated by analyzing the single particle.The filtration flow of drilling fluid and the migration of wet particles on the drum sieve are analyzed,and the processing capacity of the solid-liquid separator and the expression of the migration velocity of the solid phase in drilling fluid are given.The index(moisture content)for measuring the treatment effect of solid-liquid separator is described,and the expression for measuring the treatment effect of solid-liquid separator is given.In addition,the formula of power consumption of solid-liquid separator is given.(3)According to the optimization theory,the influence of each performance evaluation index on each objective function is analyzed,and the simulation analysis is carried out.Based on the multi-objective optimization theory,a multi-objective optimization model is established.Two typical multi-objective evolutionary algorithms NSGA-? and MOEA/D are analyzed,and the MOEA/D algorithm which is better for solving this problem is selected and improved.In the MATLAB,the multi-objective optimization model is solved by using the original algorithm and improved algorithm.And the results show that the improved algorithm has faster convergence and the solution set has better distribution when solving this kind of problem.(4)Based on the experimental prototype of solid-liquid separator,a functional experiment was carried out on the basis of the optimal solution set.The experimental results show that when the optimal individual is used as the rotating speed of solid-liquid separator,the comprehensive performance of solid-liquid separator can be improved,and the feasibility of multi-objective optimization model and algorithm is verified.One of the optimal individuals for solid-liquid separator processing effect increased by 0.1%,solid phase migration speed increased by 11.6%,and the power consumption decreased by 3.7%.