Tech Note: September 2014
Compact Emergency Lube Oil System
New Technology System: Emergency Lube Oil Pump Systems based on AC / UPS / VFD Technology and Other Commercially Available Components
Historically, almost all emergency lube oil pumps for Steam Turbine-Generators, Compressors and Pumps, and other rotating machinery have been based on either DC battery power or on auxiliary steam power. These usually work, but do have drawbacks.
TRI Transmission & Bearing Corporation has a new generation emergency lube oil pumping system that addresses these drawbacks.
DC EMERGENCY LUBE OIL SYSTEM DRAWBACKS
- Large banks of DC batteries have to be handled with a great deal of caution.
- DC motors must be specially designed for speed stabilization.
- DC motor starters with large resistors that step up the speed are a special order item.
- DC switchgear often is problematic.
- It is difficult today to find electrical suppliers who have any significant understanding of DC power systems. It is difficult to get DC components that you need, even when you have exact specifications for equipment that was commonly available a few years ago.
- Steam powered oil pumps require the inlet steam valve to be “on” in order for the oil pump to work when it is needed. Many steam control valves are old and likely have not been serviced because they are not understood, and often are closed to save steam. They are rarely removed, cleaned, and refurbished and therefore, steam powered oil pumps sometimes do not function properly when needed.
THE AC SOLUTION PROVIDED BY TRI
TRI has developed an Emergency Lube Oil System that is compact (small foot print) and is based on current AC technology that is commercially available. AC powered pumps start oil flowing immediately and reach full flow within 0.7 seconds, faster than many DC powered pumps.
The oil pump is positive displacement, C-face mounted to a motor, operating at high speed to reduce size and complexity, and is commercially available. A critically important point is that the cost is substantially lower than any DC based system.
The current AC technology includes an Uninterrupted Power Supply (UPS), switchgear, transformer and variable frequency drive (VFD), all commercially available, though they must be sized and specified to work together.
A key element is the VFD. The start-up acceleration rate is a “compromise” between being fast enough to meet the lube oil requirements of the plant’s process equipment, and slow enough to limit the “in-rush” current to be well within the capability of the UPS.