Standard Working Condition Template And Modeling Research For Cement Combined Grinding System

Cement is one of the main building raw materials of our country’s housing construction, its production is world leader. Due to low efficiency and high energy consumption of cement production grinding system, its energy saving has become a more and more attention hotspot in recent years. Grinding system combined by roller and ball mill is widely used in our country because of its characteristics of high pressure and batter grinding ability. Its production process has the characteristics of process parameters with big fluctuation range, process conditions with changeable operation with complex, and has large delay and multivariable; nonlinearity for production environment, so it’s stable and efficient control is significance. Around this problem, this paper takes intensive study in working condition template, modeling analysis and application. The main contents are as follows:(1) According to the process of grinding system of different cement plants, combined grinding system is divided into opened grinding system and closed grinding system by analyze process characteristics. Considering that the condition of grinding production system is divided into different intervals, the basic construction method of working condition template for university and multivariate characterization is given. In order to improve efficient operation level of operators, select the key parameters of each link respectively referring to cement plant design code(GB 50295-2008), in this paper from the experience of outstanding field combined with the data analysis of two kinds of grinding production to establish their own working condition templates with operational recommendations. For combined grinding system with opened grinding process, it establishes a set of working condition templates with operation suggestion. Establish a working template of ball mill load represented by multivariate for the small range of operating parameters of closed grinding system. Comparison of operational recommendations in working online display software and the operation of workers verifies the rationality and effectiveness of working condition templates. This part of contents lays the foundation for T-S fuzzy modeling and typical operating model.(2) Because of the working characteristics of a small amount of process equipment of opened combined grinding system and great influence of adjacent parameters, the various links model of opened grinding system is established by T-S fuzzy modeling method based on working condition template. Roller press process selects materials feeding quantity and weighing bin material as input variables and output variables and Ball mill process selects collecting fan speed and out-mill elevator current as input variables and output variables respectively according to two aspects and three cases of working condition template for opened grinding combined grinding system. The modeling sample data are got by collecting parameter data and filtering processing. T-S fuzzy model parameters are identified by method of least squares and the models are combined to get final T-S fuzzy model through the membership function. Randomly select the data covering all the condition to simulate and results show that the model is of high precision and provides basis for design of automatic control.(3) Because of the working characteristics of stable closed-loop and stable working parameters of closed combined grinding system, the closed grinding system global model based on least squares support vector machine(LS-SVM) is given in a typical working condition(out-mill elevator current in 125~130A). It selects circulation fan speed, separator speed and collecting fan speed as input variables, out-mill elevator current as output variables. Collect historical data of typical operating conditions to get sample data after filtering processing to set up a whole model with three inputs and one output of closed grinding system through simulation training and test. Compared with neural network modeling for simulation, LS-SVM model built has more effective, more accurate and faster fitting capability.(4) This paper takes working condition features and characteristics of model for reference on the basis of one open grinding system project, a control method combined Bang-Bang and fuzzy PID is proposed for out-mill elevator current control. An application software of cement combined grinding automatic control system and DCS interface program are developed. Running effect shows that control scheme can accelerate convergence speed of the controlled volume tracking error; verify the validity and practicability of control system. It improves the level of automation of combined grinding system production, keep production process at a higher load, small current fluctuation, stable and efficient state in a long term, so as to realize its energy saving. It has application value in practical engineering.