The steel industry uses infrared thermometers because the product is in motion and temperatures are very high. A common steel industry application is temperature at the continuous caster, where molten steel begins its transformation into slabs. Reheating steel to a uniform temperature is critical to preventing deformation, and infrared thermometers are used to measure the temperature inside reheaters. In hot rolling mills, infrared thermometers are used to check that product temperatures are within rolling limits. In cold mills, infrared thermometers monitor the temperature of steel while it is cooling.
In the glass industry, the product is also often in motion, and is heated to very high temperatures. Infrared thermometers are used to measure temperatures in the melt furnace. Portable sensors measure the exterior to detect hot spots, and the temperature of the molten glass is measured to determine proper furnace exit temperature. In flat glass production, sensors measure temperatures at each processing stage. Incorrect temperatures or rapid temperature change can result in uneven expansion and contraction. For bottle and container production, molten glass flows into a forehearth, where it is kept at uniform temperature. Infrared sensors are used to monitor the temperature of glass in the forehearth so it is in proper condition when it reaches the exit. In glass fiber production, infrared sensors are used to monitor the temperature of the glass in the forehearth, and also in the curing oven. Another application for infrared sensors in the glass industry is in windshield production.
In the plastics industries, infrared thermometers are used to avoid contamination of the product, to measure moving objects, and to measure plastic at high temperatures. In the blown film extrusion process, temperature measurements to adjust heating and cooling help maintain the plastic's tensile integrity and thickness. In the cast film extrusion process, sensors help control temperatures to maintain proper product thickness and finish uniformity. In sheet extrusion, sensors allow the operator to adjust the die heater and roll cooling to maintain product quality.
Using a portable thermal imaging system, maintenance personnel can look for potential or actual problem areas. Examples include overheated windings in a motor, plugged cooling fins on a transformer, bad connections on a capacitor bank, and heat buildup on the cylinder heads of a compressor. Any problem that manifests itself with increased heat, or a temperature profile that stands out from its surroundings, can be addressed with a portable thermal imaging system. In many cases, problems can be found in time to correct them, before they require shutting down the process.
In the petrochemical industry, refineries use thermal imaging systems in regularly scheduled preventive maintenance programs. These programs include process furnace inspections and thermocouple validation. In process furnace inspection, infrared imagers are used to inspect heater tubes for carbon scale buildup. This buildup, which is called coking, results in higher furnace firing rates and increased tube temperatures. These higher temperatures can reduce heater tube life. Because coking prevents the product from absorbing the tube's heat uniformly, areas where coking occurs appear warmer than other parts of the tube surface when using our infrared thermometer.