Research On Quality Control Of Cement Raw Meal Based On Automatic Proportioning

Quality control of raw meal is the foundation of cement production. Raw meal with high and stable quality can not only makes quality of clinker stable, but also reduce the difficulty during clinker burning. Lime saturation factor, silica modulus and aluminum modulus are common indicators of raw meal quality, and the pass rate of them are directly reflect of raw meal quality. In our country, proportioning process of cement raw meal is mainly rely on manual or semi-automatic control which has large time delay. Operators adjust the proportions based on themselves’ experiences but not accurate calculation, so it is impacted much by personal subject and the quality of cement raw meal fluctuates. Some domestic cement companies applied element online analyzer earlier which can test the constituents on belt or airslide directly and real-timely. It provides basis for the automatic calculation of proportioning. Therefore, basing on research status at home and abroad and using advanced control algorithms to achieve scientific and automatic in quality control of raw meal has important significance for quality controlling of production and stability of rotary kiln system.Basing on deeply understanding of raw meal quality control in several domestic cement enterprises, this paper presents design schemes for both off-line and on-line raw meal quality control. The main contents of this paper are as follows.(1) Off-line raw meal quality control system can’t get feed back of raw meal composition real-timely so they use data from the laboratory once per hour. Aiming at special conditions, we designed expert controller. For solving defects of off-line mode, we summed up experiences from operators and laboratory staffs plenty as rule base of expert controller so that the automatic control can simulate human’s behavior. Using incremental optimization to calculate proportions, it reduced errors caused by fluctuations of raw material composition.(2) On-line raw meal quality control system can get feed back of raw meal composition real-timely rely on element online analyzer. Online analyzer can be divided into before and after mill application due to different principles. Both of these two applications can analyze raw meal in real time so they decrease time delay a lot. We use similar control scheme for these two applications. According to feed back of the analyzer and set points of the modulus, the system choose one from bias controller, trends controller and feedforward controller to output different conditions of three modulus to be inputs of expert controller to putout corresponding proportions.(3) According to characteristics of off-line raw meal quality control, we designed a software for off-line quality control. It was totally off-lined that neither get analyzed data in real-time nor send any data to the DCS. Analyzed data are inputted artificial and calculated proportions are shown on the software and then inputted into DCS by operators. This software was developed by Visual Basic.(4) According to characteristics of on-line raw meal quality control, we designed a software for on-line quality control. It connected to the DCS and the analyzer via OPC. We use SQL Server database to read and write data real-timely. And it was also developed by Visual Basic.