Improving the Energy Efficiency in Iron and Steel Industry by Electric Motor Retrofit
AbstractIn iron and steel industry electric motor systems consume around 7% of total energy use. This rate is even more in some special applications. Motor systems include motor driven units such as rolling mills, pumps, conveyors, fans and material handling equipment. In many cases motors used in this industry are aged motors of standard efficiency class that are consuming much more energy than the new generation energy efficient motors. Solution to this problem is to retrofit the existing even healthy standard efficiency motors by the new generation energy efficient motors. In some countries governmental regulations makes it mandatory to retrofit the standard efficiency motors with the new generation energy efficient class motors, where in most countries around the globe this matter remains as recommendation. Depending on the energy cost in each country the pay-back periods varies between 2 years to 6 years. For the countries such as Turkey where the energy prices are very high the pay-back periods for electric motor retrofits will be about 2 to 3 years or less than that. This means that a motor retrofit will cover the installation and new motor cost mostly within approximately 2 to 3 years or less and then energy and cost saving will start for free thereafter. Retrofit means replacing and old but operating healthy motor of standard efficiency with a new higher efficiency motor.In this investigation several scenarios will be presented on the energy and cost saving by motor retrofit and pay-back periods will be determined in details. Importance of the dependency on the energy prices, benefits of motor retrofit to the iron and steel industry and environmental pollution will be explored with several examples when using different sizes of electric motors. It will be shown that the size of the motor plays an important role on the pay-back period and that the energy and cost saving is more significant for retrofitting small and medium size motors up to100 kW, which are more commonly used motor sizes in the iron and steel industry.