The Research Of Control System For Condenser-cleanout Robot In Thermal Power Plant

Condenser is one of the key equipments in thermal power plant. It is the cold source of the thermodynamic cycle of the large steam turbine, and it can decrease the exaust pressure and temperature of the steam turbine, and enhance the cycle thermal efficiency of the turbogenerator. Due to the unpure cooling water and chemical reactions during heat exchange when the condenser is running, the fouling not favorable for heat tranfer is accumulated in the inner wall of condenser tube. These fouling has subsequent of harms: severely decreases the heat exchange capacity of the condenser; lowers the vacuum degree; increases energy consumption; and probably leads to accidence due to the occulation of condenser tube and followed by erosion and perforation. According to industry R&D projects in Hunan Province and Hunan scientific and technological project, and the high-efficiently safe production and energy saving requirment of the nation, we analyzed the advantages and disadvantages of the current fouling-cleaning methods, and desined a new scheme for condenser fouling cleaning in power plants by a robot, whose system structure and control system were well designed and explainated.According to the water chamber instructure and tube bundle layout of the condenser, first of all, this thesis introduced the system insructure of the robot: the two-joint manipulator arm, and the track mobile robot body. The contol system of the robot was well studied. Then, the software and hardware of the robot control system was well developed. The control system consists of industrial computer, PLC and touch screen. As host computer, the industrial computer monitors robot's operation process through RS-485 serial interface bus. As the key control device of slave computer, PLC controls the electromechanical equipment of the robot through serial interface bus. As the field window of human-computer interface, touch screen realizes the operation of the field devices and indication of the status information. Finally, controller of PID was designed accroding to the pressure control requirment of the high pressure water jet. Studies showed that such controller could make pressure of high pressure water self-regulating and steady in the scheduled value; and the self-adaptive fuzzy PID controller was designed and verified by the study to satisfy the control requirment of the cleaning robot, such as adding chemical drug dosages, accurate location for electro-hydraulic servo valve and two-joint arm cleaning spray gun, and so on.The results of the study resolved the problem of the automaticlly cleaning of condenser fouling in power plant; improved the effect of heat transfer of condenser; increased the operation efficiency of steam turbine unit; and secured the safe and efficient operation of condenser in power plant.