The Overlooked Accumulator: How a Silent Device Safeguards Turbine Systems
Many operating personnel know only that an accumulator exists. Some cannot even tell where it is installed or what it actually does. So why does this device get overlooked? First, unlike pumps, valves and bearings, the accumulator has no temperature, vibration or current monitoring. Second, it simply “stands quietly” — when system pressure is normal, no one notices it is there. Third, operating procedures rarely describe it clearly, and there is little dedicated training on it. In turbine systems, however, the accumulator plays a critical role. It is mainly installed in the hydraulic control oil system (EH oil / governing oil) and the lube oil system.
1. How the Accumulator Works
Inside the accumulator, an inert gas (usually nitrogen) is separated from the hydraulic oil by an elastic diaphragm, bladder or piston. Its energy cycle works in two stages:
- Energy storage: When system pressure rises, hydraulic oil enters the accumulator and compresses the gas. The gas volume shrinks and its pressure increases, so energy is stored in the form of compressed gas.
- Energy release: When system pressure drops or a large flow is momentarily required, the gas expands and pushes the hydraulic oil back into the system, supplying flow or holding pressure.
This is exactly why, after an oil pump stops, the oil pressure does not drop to zero immediately but declines slowly — the accumulator is at work. During operation, if a pump suddenly fails, the accumulator buys operators precious golden time to respond.
2. Main Roles of the Accumulator
| Function | Description | Benefit |
|---|
| Store pressure oil & emergency supply | When a sudden leak or short pump failure occurs, the accumulator quickly releases pressure oil to hold oil pressure briefly, ensuring valves and actuators still act. | Buys time for operational response |
| Absorb pressure shocks & buffer pulsation | Pump start/stop and fast valve switching create pressure fluctuation and water-hammer shocks; the accumulator absorbs them and reduces oil pressure pulsation. | Protects pipes and pressure components, cuts vibration |
| Maintain system pressure stability | When small amounts of oil are used and pressure drops slightly, the accumulator releases oil to compensate. | Stabilizes working pressure, avoids frequent pump cycling and reduces energy consumption |
| Compensate for leakage | Minor internal leakage in hydraulic valves and seals slowly lowers pressure over long runs; the accumulator continuously tops up a small amount of oil. | Maintains system pressure over time |
3. Operation Monitoring and Inspection
- Monitor whether the EH oil main pipe pressure and the lube oil main pipe pressure are steady, and check for abnormal fluctuation.
- Inspect the accumulator appearance: leakage, vibration, abnormal noise, and frosting or oil seepage at the charging valve.
Conclusion
The accumulator is a quiet but indispensable guardian of turbine hydraulic and lube oil systems. Although it is easy to overlook, it stores energy for emergencies, absorbs pressure shocks, stabilizes system pressure and compensates for leakage. Regular monitoring of oil pressure stability and careful visual inspection of the accumulator are simple steps that can prevent unexpected downtime and protect the entire system.
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