Torpedo car shell temperature measurement.
In the steel making industry molten iron is transported from the blast furnaces using torpedo cars capable of carrying 200 to 500 tons of molten metal. The vessel itself is lined with a protective refractory brick, which over time deteriorates due to the corrosive nature of the molten metal. If refractory wear is not detected and repaired, the bricks can wear thin and allow the heat of the molten material to transfer to the metal shell of the car. The intense heat can cause significant damage, in the worst case a breakout. In addition to being a safety hazard a breakout in the wrong location can halt production in the mill for a significant period of time.
While relining the car prematurely is wasteful and expensive, waiting too long to reline can be dangerous and even more costly. Since every car has unique wear characteristics, relines based on fixed schedules are not the optimum choice.
Monitoring of the shell temperature with a line scanning infrared thermometer can be the ideal method to determine lining life and avoid costly and dangerous accidents.
Measuring point
Experience has indicated that the best time to make a temperature measurement of the vessel is just after the molten material has been removed. It is at this time that the oxygen in the air interacts with the molten material. This interaction tends to heat the refractory walls to temperatures higher than when the vessel is at full capacity.
A typical application would require a minimum of two sensing heads located on each side of the torpedo car. If monitoring the bottom of the vessel is critical, a third scanning sensor should be placed at the pour position where the vessel is rotated about its axis.
The first two sensors should be mounted to scan across the cars in a vertical direction as the cars pass through the field of view. In this way the movement of the car can be used to create two or three-dimensional images reflecting the shell temperature.
Based on the size and cylindrical nature of the torpedo cars the heads should be located 5-7 metres away. This makes it easier for the sensor to view and detect any hot spots that may occur near the top and bottom of the cars.
Computers and software
The sensors are connected to a PC in the control room via an Ethernet cable. The ScanIR operator interface software package allows users to setup and monitor each sensing head based on individual process requirements. An external contact closure indicating the car’s presence, allows the software to initiate a save of both image and temperature data, which can be time stamped if required.
The software provides users with on-line or off-line capability depending on needs and it provides data capture as well as display capability.
For more information contact Steve Edwards, R&C Instrumentation 0861 11 4217, [email protected], www.randci.co.za
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