Research On Moisture Detecting Device And System Of Sintering Mixture

Sinter is the main raw material for ironmaking,which is formed by burning a sintering mixture mixed with water.In the process of firing the sinter use the sinter mixture,the water content of the mixture has an important impact on the product quality of the sinter and the economic benefits of the sinter plant.Too much or too little water content of the sinter mixture will affect the yield,sintering speed,coke ratio and fuel utilization factor of the sinter.Therefore,the realization of rapid and accurate detection of the water content of the sintering mixture has important reference significance for the control of the water addition of the mixture,and has important practical significance for improving the economic and environmental benefits of the sintering plant.At present,the detection methods for the moisture content of the mixture in sinter plants are mostly based on manual sampling and drying calculation or use intermittent sampling device detection.This measurement method has a long measurement period,high time cost,and large lag in the control of the amount of water added to the material.Based on this background,an on-line detection device and detection system for the moisture content of sintering mixture was designed.The article introduces the common methods in the field of material moisture detection,combined with the particularity of the mixture and the moisture detection site environment,and analyzes and compares the thermal drying type,Karl Fischer type,near-infrared type,microwave type,neutron type,and conductivity type moisture detection.The advantages and disadvantages of the method,the online continuous measurement method based on the conductivity of the mixture moisture is selected as the research object.The conductance characteristics of the sintered mixture are analyzed,and the AC bridge conductance measurement circuit and the impedance divider conductance measurement circuit are designed and compared.The hardware circuit and software program of the moisture detection system are designed.In terms of the hardware circuit,the power circuit of each voltage level required by the hardware circuit is designed;the design includes the excitation source generating circuit,the signal amplifier circuit,the band-pass filter circuit,and the whole Analog circuits such as wave rectifier circuit and conditioning circuit;the digital circuit part with STM32 single-chip microcomputer as the core is designed to realize the collection and preprocessing of material moisture content and material temperature signals.In terms of software program,based on the integrated development environment Keil MDK,it has designed a sampling delay program,ADC data acquisition program,data processing program,lower computer online upgrade(IAP)program,digital tube display program,and data sending program in a modular manner.Based on software such as Visual Studio and Factory Talk View Studio,the program design of functions such as moisture reading,display,storage,alarm and automatic calibration of moisture measurement model is completed in the upper computer.In order to reduce the influence of the shape,thickness,density and contact pressure of the electrode and the material on the measurement accuracy of the moisture detection device,the style of the conductivity sensor and the shunt sampling and shaping mechanism are designed.In order to improve the measurement accuracy of the conductivity sensor,the optimal size of sensor electrode length,width,thickness,spacing and material thickness is determined through experiments.The moisture detection device was calibrated and the moisture measurement model was determined.In order to eliminate the influence of the change of material conductivity caused by the temperature change of the material on the accuracy of the measurement model,the temperature compensation experiment of the material moisture content was carried out,and the temperature compensation model was determined.A dynamic test was carried out on the moisture measurement model combined with the temperature compensation model,and a relatively ideal experimental result was obtained.The conductivity type sintering mixture moisture detection device and detection system designed in this design have stable working conditions and high measurement accuracy.The maximum absolute errors of static and dynamic tests are 0.12% and0.15%,respectively,which are less than the 2% and 3% required by the sintering plant.Standards meet the design requirements.This moisture detection device and detection system can not only detect the moisture content of the sintered mixture,but also apply to the moisture content measurement of grain,soil and other powdery materials after calibration,and has a relatively wide range of applications.