[Abstract] To address the outdated electrical control technology of overhead cranes, this paper proposes improvements to the electrical system of a multi-functional overhead crane used in carbon roasting, employing frequency converters and PLCs. The paper details the specific improvements made and their subsequent effects, demonstrating how the improvements meet various process requirements of the crane and enhance its overall performance.
[Keywords] Multifunctional overhead crane; frequency converter; PLC; speed control; monitoring display
The carbon plant of China Aluminum Qinghai Branch has a total of 6 multi-functional overhead cranes for anode baking in its three anode baking workshops. These cranes are dedicated operating equipment for anode baking furnaces and perform the following operations: conveying anodes between the baking furnace and the grouping and ungrouping stations; loading anodes into the baking furnace pit using anode clamps; adding filler material into the furnace pit using filler pipes; sucking high-temperature filler material out of the furnace pit using the suction pipes of the pneumatic conveying equipment; removing anodes from the baking furnace pit using anode clamps; and moving other equipment in the workshop (combustion rack, air blowing pipe, thermocouple rack, flue gas rack, flue gas measuring rack, cooling rack, furnace wall, etc.) using a 10t auxiliary hook. The five calcining overhead cranes in Workshops 1 and 2 were put into operation in 1987. Their electrical control used relay-contactor control, which resulted in low control level and high crane failure rate. In order to ensure the stable operation of the cranes and keep up with the development of modern electrical control, frequency converters and PLCs were used to comprehensively upgrade the electrical system of the entire crane, hoping to better solve the problems existing in the operation of the cranes and improve the equipment level.
1 Solution
1.1 Working environment of overhead crane
The overhead crane operates on a three-shift system, with each shift lasting eight hours, and operates 365 days a year. The working environment contains large amounts of carbon dust, hydrocarbons, and asphalt, and the ambient temperature can reach up to 55°C.
1.2 Composition of the overhead crane
This roasting overhead crane mainly consists of three parts: the main trolley, the auxiliary trolley, and the electrical control system. The main trolley serves as the bridge of the multi-functional roasting overhead crane, running along the longitudinal track of the workshop and equipped with a 10t electric hoist for specialized lifting tasks. The auxiliary trolley is the core of the multi-functional roasting overhead crane, housing the main operating tools, the operator's cab, and the electrical control system. The auxiliary trolley can move laterally along the track on top of the main beam of the main trolley.
The electrical control system uses a PIC programmable logic controller and is centrally operated on a control panel in the control room. The control panel is also equipped with a color touch screen, which can display the real-time operating status of each electrical component and system, as well as the location and cause of fault alarms. A wireless signal exchange device is used to control the ground equipment.
For details, please click: Application of Frequency Converters and PLCs in Multifunctional Overhead Cranes for Baking
