The relentless demand for operational efficiency and equipment reliability in mining places immense importance on effective shaft sealing. This article from shaft specialist SealRyt explores the benefits of a Double Flush Inlet configuration, validated through Computational Fluid Dynamics (CFD) simulations, to ensure optimal sealing in large rotating equipment. By addressing common challenges and identifying best practices, a spokesperson from the company said: “we aim to empower mining companies to prevent costly leaks and extend equipment lifespans.”
The Importance of effective shaft sealing
Large rotating shafts are critical in mining operations, primarily driving equipment such as slurry pumps. A reliable sealing mechanism is critical to maintaining equipment integrity, avoiding downtime, and preventing hazardous leaks. Lantern rings, a key component in sealing systems, act as reservoirs for pressurised barrier fluids, ensuring a robust seal within the stuffing box. Maintaining a pressure differential of at least 15psi between the flush fluid and the process/media is essential for consistent performance.
Flush configurations compared
This analysis focuses on three common flush configurations:
1. Single flush inlet
2. Double flush inlet
3. Single flush inlet with reduced outlet drain
Simulations were conducted using a SealRyt PackRyt Bearing with an Integrated Lantern Ring (BLR) and a large slurry pump. The PackRyt Bearing’s tight tolerances and advanced design allow for precise control over fluid dynamics within the stuffing box, resulting in satisfactory sealing. For plants relying on packing only to seal their shafts, the flow rates can vary drastically from installation to adjustment. Additionally, achieving the crucial 15 psi differential needed to prevent process material from entering the stuffing box is much more challenging with packing-only systems. Other bushing products that lack the tight tolerances of the PackRyt Bearing are likely to experience sealing results similar to packing-only systems.
Key findings
1. Config A: Single flush inlet
This setup introduces flush fluid at 300psi, but the pressure drops by 8psi before reaching the lantern ring. With only a 7psi differential, the seal fails to maintain consistent performance, and thermal expansion further decreases the flow rate over time.
2. Config B: Double flush inlet
In this optimal configuration, two inlets supply flush fluid at 300psi. The pressure drop to the lantern ring is minimal (2psi), achieving a 13psi differential—well within the recommended range. The initial flow rate of 8.5 GPM is sufficient, and the system remains stable even with thermal expansion. For shafts over 7in in diameter, this configuration is highly recommended wherever possible to ensure reliable sealing.
3. Config C: Single flush inlet with reduced outlet drain
Here, the inlet flush also starts at 300psi but suffers a 10psi drop before the lantern ring. The reduced outlet drain exacerbates pressure loss, allowing process media to breach the seal. The flow rate dwindles to 1.3GPM, leading to seal failure and potential heat damage.
Why double flush inlet works best
The double flush inlet configuration ensures a robust pressure differential and maintains consistent sealing performance, even in high-pressure, high-heat environments. Its ability to distribute flush fluid effectively prevents the media from compromising the seal and reduces wear and tear on equipment. Longer nose lengths in the bearing design further enhance the fluid restrictor’s effectiveness, a feature critical in mining operations where stuffing box construction often limits single inlet efficacy.
Considerations for effective sealing
While choosing the optimal flush configuration is essential, other factors that significantly influence sealing performance are as follows:
Startup procedure: Proper startup procedures ensure that seals are not exposed to unnecessary stress during initial operation. Gradually bringing systems up to operating pressure and temperature minimises the risk of early failure.
Shaft condition and alignment: A well-maintained and correctly aligned shaft prevents uneven wear and ensures consistent contact with the sealing surfaces. Misalignment or damage to the shaft can lead to premature seal degradation.
Flush supply quality and pressure: The quality of the flush fluid—free from contaminants and debris—is critical. Consistent and adequate flush pressure ensures the barrier fluid maintains its protective role and prevents process media from breaching the seal.
The realities of mining operations
In mining operations, conditions are rarely ideal. Compromises are often necessary, and the best-run operations excel by problem solving and making the most of available resources. This includes seeking expert advice when needed and remaining skeptical of the status quo. Leveraging sealing experts can provide tailored solutions that address unique challenges and improve overall performance.
Better sealing practices
Better sealing practices can transform mine operations. Adopting the double flush inlet configuration can significantly reduce maintenance costs, improve operational reliability, and enhance safety. Mining operations using this configuration benefit from:
Reduced risk of seal failure
Improved longevity of rotating equipment
Lower downtime and associated costs
Conclusion
CFD simulations confirm that the Double Flush Inlet configuration is the superior choice for shaft sealing in mining applications. By embracing this innovative approach and incorporating considerations like startup procedures, shaft condition, and flush supply, quality, mining companies can safeguard their operations against leaks, downtime, and equipment damage—ensuring smoother, more efficient processes. For shafts over 7in in diameter, a Double Flush Inlet configuration is strongly recommended.
For more information visit: www.sealryt.com
Clik here to view.
Clik here to view.
Clik here to view.
