Diesel engines are the mainstay for current seaborne cargo carriers. While these engines suffered from inefficiencies a couple of decades ago, newer engines have a rationalized weight-to-power ratio and are significantly more efficient for propelling fully loaded freight ships.
Marine diesel engines mounted on large vessels exhibit varying degrees of vibration. When the natural axial and torsional vibration frequency of the engine integrates with the frequency of vibration from an external source, or when the engine itself generates out-of-balance forces within, it creates first and second order movements. If the combined vibration levels cross the minimum threshold, it can severely damage, deform or break critical engine components.
In this context, the client requested L&T Technology Services (LTTS) to design and deploy an external second order vibration damper for their marine engines.
The client wanted LTTS to develop a cost-effective vibration compensation solution that could be independently retrofitted in the steering room and create forces of defined magnitude and frequency to dampen second order vibrations.
Product design was required to be simple, containing a minimal number of moving parts, with no external sourcing, to maintain cost efficiencies. To ensure the new solution’s reliability, a 1:1 prototype along with its control system was also required to be tested for a minimum of 500 hours operating under accelerated conditions.
LTTS obtained the values of second order vertical moments of the engine from the engine manufacturer to calculate the power related unbalance (PRU). This allowed LTTS to define the subsequent course of action including:
- Designing, prototyping, and developing a 4.5-ton vibration compensator
- Designing an electric drive system to turn two contra-rotating eccentric masses of 500 kilos each
- Identifying the correct gearbox for the compact system
- Developing a starting algorithm to replace the air starter motors in future variants
- Testing the complete system’s performance on an engine test bed for 500 hours
The compensator system is designed, with a limited number of bought-out parts, using manufacturing methodology based on frugal engineering principles. The system is reliable owing to its simplistic design utilizing a minimal number of parts.
- Cost Saving - Reduced manufacturing costs by 50 percent
- Energy Efficiency - Increased energy efficiency by 20 percent using a regenerative power feedback system
Keywords: Marine Diesel Engine, Vibration Compensation System, Energy Efficiency, Cost Saving, LTTS, ARC Advisory Group.