(*) Irajá Ribeiro Junior and Luiz Henrique Crestana
This aspect is usually analyzed in depth only when damage occurs or when the service life of the components is reduced. However, the analysis of a lubricant may provide an indication of future problems regarding the suitability of the lubricant, future lubricant failure can be prevented.
The demands of manufacturers and users regarding the performance of lubricants have increased considerably, seeking constant improvement in order to reduce operating costs, increase reliability, and reduce the need for repairs and maintenance. The use of synthetic lubricating oils rather than mineral oils provides all these benefits, which are already known in the industry by the users of these special products.
While these benefits are known and perceivable, their proof can be complex, because they are also less tangible and in some cases difficult to measure. An additional benefit provided by the specific synthetic oils, which have been increasingly explored by presenting more tangible, i.e. measurable results, is the reduction of energy consumption. Considering this benefit, in addition to the already known mechanical benefits of reliability and less damage to the environment, it is possible to financially prove the benefit of using synthetic oils for reducing power consumption.
In the steel industry, because of this opportunity and the great amount of gearboxes in the plants, the attention given to this benefit has been growing. From the user's point of view, the reduction of total operating costs due to longer service life of the oil, lower consumption of spare parts, and lower power consumption, are shown to be significant improvement factors in the process. The approach of measuring and proving the results in terms of energy efficiency has been increasingly used for financial proof of return by the users. At Klüber Lubrication, the concept of sustainability and energy efficiency is already a reality. A team of highly skilled and technically qualified professionals for the confirmation of the results has already shown remarkable outcomes obtained in large customer and application segments such as Steel, Pulp and Paper, Bioenergy Power Plants, Cement, Mining, and Food.
References in Steelmaking - Cooling Towers
The concept of energy efficiency with special lubricants is already bearing fruit in the steel industry, as illustrated by two recent studies made in large steelmaking groups, one in South Korea, the other in Brazil, showing significant gains in cooling tower fan gearboxes.
The main operational challenges in this type of equipment are the reduced service life of the lubricant due to contamination by water, and the difficulty of access to the gearboxes, which makes maintenance and oil change dangerous and difficult. It is possible, by special lubrication, to increase the change interval, and yet getting financial gains through the reduction in energy consumption. In both plants, for this application, oils based on high-performance polyglycol oil were recommended as a replacement for the mineral oil. These products can withstand operating temperatures of up to 160 °C and feature a load-carrying capacity far higher than that of mineral oils, even in the presence of moisture. Polyglycols also offer a service life much longer than that of the mineral oils due to their excellent resistance to aging and oxidation, thus providing longer intervals between oil changes or top-up. To make a correct measurement of energy and check the reduction of consumption in this type of equipment, it is necessary to control process parameters such as the flow of water and air, among other variables, as well as the motor power to ensure that the measured results are comparable and reliable.
The results of energy savings must be presented for the measurement under the same thermal stress, and considering specific consumption depending on the controlled parameters. The consumption reduction results, already corrected by the verification calculations, are shown below for the two measurement cases mentioned above.
It was observed that the savings reached were 4.9 % and 6.2 % in the equipment of Brazil and South Korea, respectively. These percentages provided payback within less than 10 months in both cases, considering only the economy of power and a lubricant service life of at least 4 years, which is much higher than the period of approximately 1 year normally assumed for mineral oil.
The replacement of mineral by synthetic oil provides higher equipment reliability and increased intervals between oil changes. Additionally, to financially justify the change in the short term, it is possible to measure the reduction of power consumption, which must be proven by the measurement and verification process patented by Klüber Lubrication. Through this measurement, it is possible to prove the financial return on investment much faster than that obtained through the benefits traditionally known, but requiring complex measurement.