In smelters, hot metal cranes are used to transport molten pig iron into special ladles. The hot metal has a temperature of around 1,300 °C and is moved from the blast furnace to the desulphurization station or to another station for further processing. During this transportation procedure, it is important that the cranes are not only extremely robust, precise and fail-safe in their work but also keep maintenance requirements to a minimum.
Monitoring how pig iron ladles are picked up
To monitor the procedure and ensure that the pig iron ladles are picked up properly by the cranes, safety sensors are integrated into the laminated hooks on the traversing gear of the crane system. These sensors transmit their recorded data to the control center via radio communication. The problem with this setup is that both the sensors and the radio communication system require a constant power supply. Given the high temperatures in the pig iron ladles, however, power cannot be supplied via a festoon cable; instead, it must come from a battery. This brings about another problem, namely the need for regular battery changes, which in turn interrupt the operation of the system.
A battery-free solution reduces standstills
In an effort to avoid the fortnightly battery change requirement and consequent system standstill, a customer contracted us to develop an alternative solution. After analyzing the circumstances, we recommended the installation of an autonomous auxiliary power supply. To achieve this, we developed a concept featuring a permanently excited three-phase synchronous generator that sources energy from the movement of the crane. A rectifier then converts the alternating voltage generated by this process into the required direct current and feeds it into the battery. As a result, the battery can now provide the power that the sensors require without needing to be changed, thus increasing both the availability and productivity of the system. For detailed information on how we solved the power supply problem and which products we used in our solution, take a look at our case study “Hot metal crane / Traversing gear: Heavy-duty generator DSG P reduces
time and costs of maintenance on lifting beam in raw iron production”