Gas engines
More than 1,300 employees work every day to supply more than 200,000 customers with fuels, fuel oil, liquefied petroleum gas and lubricants in their catchment area. With currently 21 branches and 60 sales offices Hoyer is the local energy supplier. Lubricants have been part of the product range since the company was founded, but it is only since 2002, when the essential operating parts of the Finke mineral oil factory and the rights to its Aviaticon trade mark were taken over, that Hoyer has also established itself as a well-known lubricant manufacturer. The Aviaticon lubricants have been developed and produced at the newly built Finke mineral oil factory in Visselhövede since 2003.
Gas engine oils, as they are developed at Finke, are a typical example of lubricants that need modern know-how for their formulation. The lubrication of biogas motors presents particular challenges. The composition of the gas often varies. In addition, some impurities in biogas, most importantly hydrogen sulphide, react extremely aggressively and release acids during combustion, which can damage the motor. This is exactly where the oils authorised by the gas engine manufacturers attack. With their balanced alkaline reserve they keep the acids in check over a long period. Where necessary they also protect motors with a low-ash additive, which ensures efficient system operation. Nevertheless, each engine manufacturer designs their motors differently, each motor is operating in individual conditions and each biogas plant produces a different gas. For that reason our gas engine oils are available in a variety of formulations.
A thorough appraisal of all parameters is carried out before an individual product recommendation is made. Technically trained sales advisers collect data on the motors, learn about the oil used to date and clarify the details of the specific operating conditions, such as, for example, high thermal stresses or particularly corrosive gas components. In addition, an analysis of the used oil for the product used to date is carried out in our OELCHECK laboratory before converting to a new gas engine oil. Only after detailed analysis of the laboratory report, taking into consideration the usage time and supplementary information on the gas type, will Hoyer Applications Engineering recommend the most suitable oil for the biogas motor.
Frank Schulze is one of the key account managers for lubricants in the Hoyer business group. When it is a question of gas engine oils, it all comes together with Frank and his colleagues Markus Schulz and Oliver Reinhardt. Frank knows: The initial test of the existing oil in a lubricant analysis is only the start of the long-term monitoring of the gas engine oil and the lubricated motor.
Depending on the engine manufacturer and type, the type of gas and its composition, the operating parameters and the service conditions, as well as the results of the preliminary investigation, the right engine oil and the first intervals for the oil tests are recommended. Based on the results of the OELCHECK lubricant analyses after the oil change, the oil change interval is then adapted individually. These intervals are normally longer and, therefore, more economical than before. They can, however, also be shorter in rare cases, especially where the gas composition varies. Ultimately the safety of the motor always takes first priority.
The operators of the gas motors send the oil samples in the analysis sets, which are supplied together with the oil, directly to OELCHECK. However, the commented laboratory reports are not sent directly by the laboratory to the customer, but are sent via the internet portal www.lab.report after an appraisal by the oil manufacturer. Then, in addition to the diagnosis, the application technicians can, based on the values determined and thanks to their years of experience, advise their clients precisely when the oil should next be changed or analysed.
Important laboratory reports, that is those marked with yellow or red by OELCHECK, are processed with the highest priority and are mailed to colleagues on site with the clients with relevant recommendations, so that these can be acted upon immediately.
The application technicians at Hoyer have used the OELCHECK lubricant analyses and the internet portal for many years. In that way a comprehensive database of almost 10,000 samples has been created. With their help, trends can be recognized with the highest accuracy and individual oil change intervals can be set. In addition, the data also provides important information to the Research and Development department at Fink Refinery regarding the long-term behaviour of gas engine oils in a range of different operating conditions. This knowledge naturally influences the further development of the products.
The state of the gas engine oil and the motor is checked and commented on in each laboratory report. Any impurities and wear processes, especially oxidation and „acidification“ of the oil, are evaluated in detail. Aviaticon gas engine oils do provide an optimised alkaline reserve, but during use they must remove the aggressively acidic products of combustion from the biogas and protect the motor from corrosive wear. Consequently the usage time is limited for even the best oils. With each lubricant analysis the acid-base balance of the used oil is tested. The acid value AN (Acid Number) shows the degree of acidification of the oil, while the base value BN (Base Number) shows the amount of base additive still available, which can work to neutralise the acids. Consequently the base value of an oil should always be higher than its acid value. If the value or the AN exceeds the BN, the engine oil should be changed promptly according to the guidelines from the engine manufacturers and insurance companies. However, since the base value does not show the neutralising capability of an oil for all acidic reacting compounds, which can occur in the oil during operation of gas motors with landfill or digester gases, the i-pH value is also always determined. This provides decisive additional information regarding the loading of the used oil with corrosive acids.
Frank Schulze: „We have used the OELCHECK analyses for years. We particularly value their speed, the quality of the assessment and the fact that a contact person is always available where we have a question.“
The power generation and secure operation of biogas motors depend on the entire system. Their perfect lubrication is, however, not easy to master. For that reason Hoyer application technicians train the employees and operators of the systems in regular further training events. In this way they get to know the world of lubricants and the interpretation of laboratory results even better and are familiarised with the optimal lubrication of gas engines.
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