Research And Development Of Load Control System For Cement Raw Material Vertical Mill

Cement raw meal grinding occupies an important position in the cement production process,and the quality of raw meal directly affects the subsequent firing quality of cement clinker.The grinding quality of raw meal is directly related to the load of the mill.At the same time,the excessive load of the mill not only affects the quality of grinding,but also affects the life of the mill.Therefore,in order to make the raw meal production process run smoothly,it is necessary to ensure that the load of the mill can be controlled within an appropriate range.The pressure difference in the mill and the thickness of the material layer are directly related to the load of the vertical mill during the production of cement raw meal,and the accuracy of its measurement directly affects the control effect of the mill load.At present,the accuracy of vertical mill pressure difference measurement is affected due to insufficient sealing.In actual engineering,the mill current is usually controlled by the mill current and the bucket elevator current after the mill,which results in a large hysteresis;The thickness of the abrasive layer cannot be measured directly.Due to the inability to accurately evaluate the internal pressure difference of the mill and the thickness of the material layer,the vertical mill often encounters the problem of downtime in actual production.As a common equipment for raw meal preparation,it will inevitably lead to the suspension of raw meal preparation.In addition,low-efficiency manual control has a large hysteresis.Frequent load fluctuations not only make it difficult to improve the quality of cement,but also invisibly increase the cost of mill maintenance.Aiming at the above problems,a load control system of raw material vertical mill is developed in this paper.The specific content is as follows:(1)Based on the raw meal vertical mill production line of a cement plant in Shandong,the process mechanism of the cement raw meal vertical mill production process was analyzed,and the key control parameters and load control ideas were determined.(2)Process historical data through sliding filtering and 3 criteria;take feed amount,mill outlet temperature,mill vibration,mill current as network input,mill internal pressure difference as network output,and use radial basis neural network to design the mill The internal pressure difference soft-sensing model is compared with the BP neural network model to verify its effectiveness;the mill outlet temperature,mill vibration,mill current,and separator speed are used as model inputs,and the material layer thickness is used as model output,using PSO-LSSVM method established the soft measurement model of material layer thickness and carried out simulation verification.(3)Summarize the excellent experience of on-site operators,establish a fuzzy rule library for the control of the internal pressure difference in the mill,design a fuzzy controller for the internal pressure difference in the mill,and construct the internal pressure difference control loop based on the soft measurement model of the pressure difference established in(2),Compared with the traditional PID to verify its effectiveness;based on the historical data of the field,a dynamic model of the powder separator speed-material thickness is established,the material thickness sliding mode controller is designed and its stability is verified,combined with the material thickness established in(2)The soft-sensing model constructs the material layer thickness sliding mode control loop and carries on the simulation analysis.(4)Based on the above results,the cement raw meal vertical mill load control system was developed and put into operation in a cement plant in Shandong,which achieved good application results.