Study On Temperature Field Coordinated Control System Of Ventilation Air Methane Thermal Flow-reversal Oxidation Device

There is huge volume of ventilation air methane (VAM) in our country. Rationalutilization of low concentration methane in VAM has double effects of environmentalprotection and energy conservation. At present, an effective VAM utilization technology isthermal flow-reversal reactor (TFRR), which is the only VAM utilization technology that isapplied commercially. However, during the operation of the large VAM thermalflow-reversal oxidation device, the temperature field of the device was uncoordinated,which had a significant impact on the performance of the device and utilization of heat. Inthis thesis, the temperature field coordinated control of the VAM thermal flow-reversaloxidation device has been studied on.Firstly, the overall plan of the temperature filed coordinated control system of theVAM thermal flow-reversal oxidation device was laid out, and control zones were adoptedto realize temperature field coordinated control. After that, an original vertical VAMthermal flow-reversal oxidation experimental set-up was upgraded for performingexperiments on temperature field coordinated control.Secondly, a lower-computer control system, based on Omron PLC, was designed,according to the control requirements, the kind and quantity of sensors and actuator for theVAM thermal flow-reversal oxidation device temperature field coordinated controlexperimental platform. The corresponding PLC modules were chosen. The ladder diagramof lower-computer control system was designed using CX-Prgrammer software.Next, an upper-computer supervision system based on the Kingview software wasdesigned, and this made the human-computer interaction possible. There were sevensupervision pictures to be developed, which included the main picture, the temperaturechart picture, the A zone historical curve picture, the B zone historical curve picture, theother temperature historical curve picture, concentration and flow historical curve pictureand preservation picuture. These pictures displayed and controlled the relevant parametersof the experimental platform. In addition, the connection between Kingview and MicrosoftAccess database was established for storing experimental data.Finally, the temperature field coordinated control system of the VAM thermalflow-reversal oxidation device was investigated experimentally. The start process of theexperimental system was investigated. The results showed that when the volume of theliquefied petroleum gas was sufficient, start-up reciprocating half period was120s, start-up time was60min, and then the ideal start-up temperature field could be reached. Using themethod of without the heating system assistance turning into the operation mode, theoxidation device could quickly realize self-maintenance running. The effect of methaneconcentration in the simulant VAM on oxidation device temperature field was studied. Inorder to facilitate the temperature field coordinated control experiment, the methaneconcentration of the simulant VAM during the oxidation device operating conditions wasselected as0.5%. The experiment of the oxidation’s A zone and B zone whole temperaturefields coordinated control showed that: Using the control strategy of changing regionalupper and lower inlet valve opening could realize the coordinated control of zone wholetemperature field. The bigger the regional inlet valve opening was, the greater its wholetemperature field would increase. The experiment of the oxidation’s A zone and B zonetemperature fields peak shift coordinated control showed that: Using the control strategy ofadjusting the switching time, regional upper and lower inlet valve opening degreedifference could eliminate the phenomenon of A zone and B zone temperature fields peakshift, and realize the coordinated control of A zone and B zone temperature fields peakshift.