Research On Automatic Rake Thickener Pharmacy Adding System Based On PLC

Coal slurry treatment as an important part of coal separating plant production process,Has a great influence on all aspects of economic and technical indicators, the quantity and quality of products, separation efficiency. Currently, how to improve the efficiency of slime water treatment in coal preparation plant,achieve closed-circuit circulation of wash water, the recovery of coal has become an important content of coal preparation plant at home and abroad research. Because it has the underflow concentration, management is convenient, the rake thickener has a broad application in slime water treatment. In the production of coal preparation plant, Settlement of adding flocculant and coagulant practices accelerated slime in concentrator of often used.At present, the concentrated operation, most of the domestic coal preparation plant adopts manual dosing way. However, the higher requirement to the worker’s manual dosing, not according to the change of parameters in the process of concentration, real-time adjustment of dosage. When the dosage is too high or too low, it will bring bad effects to the production process of coal preparation plant. Therefore, research on automatic adding thickener pharmacy systematic, has positive significance for coal preparation plant.This paper first analyzes the main properties of the coal slurry concentration, particle size, including coal slurry composition, viscosity and chemical properties, effect on coal slurry concentration and settlement. Then select the molecular weight is10000000and12000000anionic polyacrylamide single factor experiment, The two kinds of flocculants and commonly used coagulation experiment of mixing agent. By comparing the light transmittance, initial settling velocity, sediment height and other parameters are determined and the optimal dosage of reagent system. To determine the best dosage, system hardware and software design of automatic adding thickener pharmacy.The paper introduces the automatic dosing system based on the M340series PLC produced by Schneider Inc as the core, using feedforward control and feedback control method of combining. According to the installation in the thickener in coal slurry concentration and flow rate measurement of material on the highway instrument measured data and transfer to the PLC, the PLC was calculated according to the correlation algorithm in unit time feeding coal slurry in dry coal quantity, and according to the determined the flocculant dosage and coagulation inhibitor mathematic model was established, which belongs to the feedforward control. At the same time, according to the thickener turbidity of overflow value on the recruitment of the flocculant is corrected, which belongs to the feedback regulation.Automatic dosing system is composed of flow and density meter detecting element, PLC control cabinet and the metering pump. The communication between host computer screen preparation, the part of software design includes the configuration and the program of computer drawing and the host computer and PLC.