Stay cool and be fully loaded with Special Bearings
The maximum permissible temperature in gearbox bearings plays an increasing important role in critical applications, e.g. the oil and gas industry. For example, if the bearings overheat the oil will age faster and residue forms in the bearings. In a worst-case-scenario, this residue can cause a complete system shut down. The hydro dynamic "Ultra Cool Bearing" by Voith achieves top-of-the-line results even in sophisticated applications with pitchline velocities of 100 m/s. With certain design modifications, in this bearing the temperatures can be 5 to 15 °C cooler.
An inquiry by an international oil company initiated the development of BHS' Ultra Cool journal bearing design in 2005. A gear unit in the compressor train for a residual gas facility in Africa required the bearing temperatures not to exceed 90°C at full load and full speed. Under these specific conditions standard journal bearings would have reached tempatures of 105 to 110°C. This would have resulted in accelerated aging of the oil and coking in the bearings which in turn would have led to shorter oil change cycles and a higher breakdown risk of the whole plant.
The systematic modification of materials and design enabled Voith to develop a bearing that fulfilled all of the customer's requirements. The bearing material of the Ultra Cool Bearings uses a heat conductivity that is six times higher than that of other materials. Cooling channels in the material also ensure faster heat conduction by significantly reducing the heating of the oil that comes into contact with the bearing surface. The Ultra Cool Bearings are offset journal bearings. The special interior shape of two offset half-shells affix the shaft, particularly at light-duty or idling speed.
In the case at hand, the "cool bearing" significantly exceeds all expectations: Since 2006, the year of commissioning, the measured maximum temperature of the bearings never exceeded 78°C.It therefore falls well short of the required maximum value of 90°C at the frame conditions of 100% load, 1.7 bar g oil intake pressure, 49.5°C oil inlet temperature, 3.3 MPa bearing load at 90 m/s pitchline velocity. The advantages of the bearings are even more succinct when it comes to the heating of the oil: an improvement of 35% in comparison to the required maximum value of 35K was achieved. Voith Turbo BHS was able to verify the customer's positive results at its new bearing test stand in Sonthofen, Germany. For the first time, bearing tests were performed at full load and under realistic operating conditions as required by the customer. The Ultra Cool journal bearings have since been installed in ten separate projects within the oil and gas industry, and completely fulfilled all expectations. Ultra Cool Bearings are used on gear units for drive train applications such as "electric motor driven compressors" and "gas turbine driven compressor".
When compared to tilting-pad bearings, the advantages of the innovation by Voith Turbo BHS is clear; the Ultra Cool Bearings use less oil, have a higher efficiency, and better bearing damping.
Located in Sonthofen, Bavaria; Voith Turbo BHS Getriebe GmbH is a company of the Voith Group and is synonymous with gearboxes, couplings and turning gears with the highest quality and state-of-the-art technology for more than 75 years. To date, Voith Turbo BHS has more than 20 000 gearbox references with transmitted powers up to 70 000 MW.
Voith Turbo, the specialist for hydrodynamic drive, coupling and braking systems for road, rail and industrial applications, as well as for ship propulsion systems, is a Group Division of Voith GmbH.
Voith sets standards in the markets energy, oil & gas, paper, raw materials and transportation & automotive. Founded in 1867, Voith employs almost 40 000 people, generates €5.2 billion in sales, operates in about 50 countries around the world and is today one of the biggest family-owned companies in Europe.