| Mainstream soot concentration monitoring methods at home and abroad include off-line and on-line monitoring methods,off-line monitoring method is mainly about the cumbersome manual weighing method,online monitoring methods which represented by optical method are indirect weighing methods,barely have the characteristics of the soot quantity traceability,it affects the environmental protection department taking effective monitoring of law enforcement.Authorized by Shanxi academy of environment and science,according to soot concentration on-line monitoring requirements,our group design and implement a set of soot concentration on-line monitoring device based on weighing method,complete on-line and accurate monitoring of places where have ultra-low emissions of soot concentration.According to the standards of soot concentration measurement based on weighing method,we do research from five aspects in this paper:(1)Design of overall structure of the soot concentration on-line monitoring device.Finish the design of mechanical structure in the device,the soot weighing unit is a critical part in this technical research.Realize flexible automation functions like storing,transmission,sampling,discarding and weighing the embrane filter in the soot monitoring device,improve the accuracy and efficiency of the soot concentration monitoring device.(2)Design of the electromagnetic scale system.Based on the analysis onweighing principles of the existing electromagnetic scales,according to the weighing requests of the soot monitoring device,complete the overall design of electromagnetic scale which is applicable to membrane weighing method.Mainly contains the design the structure of electromagnetic balance sensor which is the core of the device.(3)Design of the circuits in electromagnetic scales.Complete the conversion from the membrane filter weight to electrical signals based on linear CCD photoelectric detection circuit,convert the electrical signals into digital signals by data acquisition circuit based on ?-? type A/D converter,signal processor unit in STM32 analyzes the digital signals and output a signal through PID control,the signal is converted to a digital signal which directly drive the current in the coil by D/A converter in PID control circuit,eventually filter membrane quality will be convertd into the current in coil.(4)Obtain the model and simulation of the electromagnetic balance system.First,obtain the model of the open-loop system of electromagnetic scales,complete parameter identification of the open-loop system by the least square method,then build FOLPD model of the open-loop system,establish the simulation model of the closed-loop system based on the mathematical models of several parts in the electromagnetic scale system.Add the adaptive fuzzy PID compound control algorithm into the mathematical model of the system,complete a intelligent PID control scheme of electromagnetic scales,realized the precise adjustment of electromagnetic scales.(5)Design and incompletate the control scheme of soot weighing unit.Through the cooperation of PLC and STM32,complete the automatic operation of the weighing unit.Use a variety of feedback signal modules for detection to ensure control precision.Draw the WinCC interfaces,realize the real-time display of monitoring data like soot concentration,manual single step control of device and data preservation.The soot concentration on-line monitoring device was settled in Shanxi Ruiguang thermal power plant for many filed experiments,the application results show that the device works normally,and conforms to the environmental protection department issued on the monitoring of soot concentration standard.It has high reliability and good scalability characteristics,overcomes the shortcomings of the existing monitoring methods,realizes the automatic and on-line monitoring of soot concentration.In the field of environmental monitoring,it meets the requirments of soot concentration based on automatic weighing method,it has some practical value... |
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