In the realm of wood pellet and animal feed production, the devil lurks in the intricacies of pelletizing processes, revealing a historical technological immobility that has plagued the industry for decades.How did we get there? First, the design and constraints of the process—despite the multitude of pellet mill manufacturers, the design and stresses on roller bearings remain uniform across original equipment manufacturers (OEMs). Bearings endure extreme conditions, including high pressure, temperature, vibration, shock, humidity, oxidation, corrosive atmospheres and material pollution—a challenging environment for optimal bearing performance. In a nutshell, it is hard to find more devastating conditions for bearings.The two traditional solutions to limit premature bearing wear are excessive greasing and oversized, poorly designed automatic lubrication systems that inadequately cater to the specific needs of the pelletizing process. There are many negative influences on the total cost of ownership (TCO) of pellet mills that result from the consequences of the current approach. High grease consumption leads to higher costs. Often, the design of the lubrication system keeps the grease under permanent pressure, in some cases up to 120 bar. This leads to premature grease deterioration due to bleeding of the grease (separation of oil and thickener). Shorter bearing lifespan compared to roller shell life leads to elevated operational maintenance costs, unplanned stoppages, logistical challenges and degraded work quality for operators.So what are the root causes of technological immobility? The interests of grease suppliers, bearing manufacturers and pellet mill OEMs align to maintain the status quo, resulting in a lack of innovation and improvement. Grease suppliers want to sell as many tons of grease as possible. Bearing suppliers and third parties for roller refurbishment want to sell as many bearings as possible. Pellet mill OEMs and their subcontractors want to sell as many spare parts as possible. The conclusion is that apart from the pellet producers, the status quo is best.Breaking the Deadlock&nbsp; There are two solutions to the dilemma. Tribology (from the ancient Greek words "tribos" and "logos," meaning rubbing or sliding, and study or science, respectively) is the study of phenomena that may occur between two materials in contact, whether immobile or animated by relative motion. This term covers, among other things, all areas of friction, wear and lubrication. Tribology provides a pathway forward by addressing the constraints of the pelleting process and overcoming the mechanical and chemical limitations of standard lubricants. Synthetic-based specialty lubricants already offer an improvement in terms of quantity reduction and extending bearing life by 10% to 15%. However, the costs per ton are significantly higher and are often not worthwhile. The solution is to modify the mechanical and chemical limits of bearings and the lubricant coating the surface of the wear parts. High-performance greases containing solid lubricant particles, such as ceramic-based specialty lubricants, level roughness and form a coating. Such a hybrid surface has the advantages of ceramic bearings without the associated costs and constraints.&nbsp;The second solution is an advanced automated lubrication system. As the majority of bearing failures result from improper lubrication, automated lubrication systems are paramount and often the standard for pellet mill lubrication. The advantages are obvious: Controlled lubricant distribution ensures no lubrication point is missed, resulting in reduced contamination and lower risks of grease mixing and breakdown, ultimately leading to lower maintenance costs. However, in most pellet plants, too much grease is applied at too long intervals.&nbsp;The ideal hydraulic film between two moving surfaces is constant (see blue line in Figure 1). Each lubrication cycle of standard lubrication systems provides too much grease at once to the roller and main bearings (if the main bearing is grease-lubricated), causing a state of overgreasing. With high pressure in the bearings, the grease is pushed out quickly, reversing the state over the long interval to underlubrication. Underlubrication leads to corrosion and excessive wear, causing premature and labor-intensive equipment failures, in a worst case causing overheating and fire. Overgreasing leads to lubricant loss, higher cleaning costs, product contamination and reduced productivity.&nbsp;An advanced automated lubrication system focuses on minimum dosability and frequency over excessive flow and quantity. Here is a real-world upgrade of an existing automated lubrication system. The existing distributors did not allow for grease volume reductions. The distributor was equipped with three PMF 50 segments, giving a total displacement of 3x (.5x2) = 3 cc. Programmed at four pulses every three minutes, it provided 20 cycles per hour or 240 cc. The existing equipment does not have an integrated nonreturn valve and was leaking.The upgrade included a Graco MSP 3 distributor equipped with 3x 05S segments, configured in a single departure. This resulted in 2x .08cc = .16 cc per segment. The total displacement was 3x (.08x2) = .48 cc. This upgrade allows for a reduction of the hourly volumes. With precise .48 cc distribution or one-sixth of the former output delivery, a much shorter grease interval is possible.&nbsp;The results of both the upgraded lubrication system and the use of high-performance grease speak for themselves: reduced grease consumption and extended bearing life.The high-performance grease allowed for up to a 96.58% reduction in grease consumption over 2,000 hours of production, leading to cost savings and improved efficiency. The almost-ideal hydraulic film in the bearings led to a factor of four increase in bearing lifespan, enhancing reliability and reducing operational and maintenance costs. As a bonus, the significant reduction in grease resulted in a better carbon footprint. Nineteen tons of annual regular grease consumption has been replaced by 900 kilograms of high-performance ceramic grease.In conclusion, embracing advancements in tribology and adopting precise lubrication systems presents a revolutionary opportunity for the pellet industry. By breaking free from the chains of technological immobility, stakeholders can usher in an era of increased efficiency, cost savings and environmental sustainability. Author: Holger Streetz&nbsp; CEO, Bathan AG&nbsp; h.streetz@bathan.ch&nbsp;

2024-03-04 - Unlocking Efficiency Through Advanced Lubrication (Biomass Magazine)

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Precise lubrication systems present a revolutionary opportunity for the pellet industry.

Unlocking Efficiency Through Advanced Lubrication

Unlocking Efficiency Through Advanced Lubrication

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Unlocking Efficiency Through Advanced Lubrication