| There are some problems in the process of treatment of coal slime water in Cheng Zhuang coal preparation plant:the press filter efficiency of coal slime was low and the filter cake moisture content was high. The filter aid was added by hand in ChengZhuang coal preparation plant,it resulted in incompletion dissolving of reagent, poor dispersibility, inaccuracy dosage, intensive labour. The above problems in coal preparation plant are universal. Through studying pressure filtration simulation and reagent adding control system,this paper aims to solve these problems.In order to analysis the influence factors of pressure filtration process, looking for the right variables for reagent dosing control,porous media model in Fluent was used to simulat the process of coal slime filter press aimed at the industrial operation parameters of fast membrane filter press used in Cheng Zhuang coal preparation plant. Distribution of different granularity coal slime in filter cake,the effect of different concentration and particle size of slime water for the filtration was analysised by the Fluent simulation.In the actual process, the coal filter layer was formed continuously, the thickness of the filter cake was also increased in succession. In this paper, the filter chamber is divided into many thin layer to simplify the filtering process by adopting the concept of " differential and integral calculus ". The region in the filter chamber was set as the porous medium when the region was filled with filter layer to analog the process of filter.Based on the filter theory and the consequence of Fluent simulation, the automatic dispensing and dosing system was designed.According to the configuration process of filter aid, the reagent tank of filter aid was designed. The reagent tank was composed of 3 chamber interconnected.The first chamber and the second chamber included agitator and water pipes aimed to soluble the filter aid.The third chamber was designed to store reagent. Filter plate was set between the second chamber and the third chamber to filter out the impurity before dosing. The reagent was token out by dosing pump from third chamberis to add to the coal slime bucket, mixed with coal slurry water. Then, various sensors and actuators were typed and designed, and electrical control cabinet based on PLC was also designed.Reagent preparation way include automatic configuration and manual configuration mode. 1766- L32 BWA PLC controller of MicroLogix 1400 series producted by Allen- Bradley company was used to control,and a Electrical control cabinet was designed. Touch screen of TPC1061 Ti producted by Beijing Kunlun Tongtai company was used.Filter aid dosing automatically control system adopted PLC(programmable logic controller) to control, using the control strategy of feedforward and feedback. In Feedforward control,the concentration of coal slime water and pressure filtration cycle were set as input variables of expert rules.In the feedback unit, a assessment model of the filter- press dewatering effect was put forward,and using the deviation value of the assessment model and its rate of change as the input signal,feedback compensation was realized by using the fuzzy algorithm.In the end, the filter aid agent preparation and reagent adding automatic control were achieved through the system. Controling the cycle of filter press filter within certain realms,the filter cake moisture was reduced 2.6%, the dosage of PAC was saved 7.24%, and the workers labor intensity was decreased.The implementation of this system has important economic and social significance. |
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