Surge occurs
when there is no forward flow of gas through the compressor and a reversal of flow occurs
. The gas that is being compressed gets pushed backward through the centrifugal compressor. When this surge (flow reversal) occurs, which can happen in milliseconds, the rotor is affected.
How does compressor surge occur?
Surge is a condition that occurs in compressors
when the amount of gas they are trying to compress is insufficient for the size of the compressor and the blades lose their ability to transfer energy from the shaft to the fluid
, causing a reverse flow of the gas.
How do I stop my compressor from surging?
- Larger Anti-surge Valve (ASV) Size with a Quick Opening Valve.
- Suction and Discharge Pipe Re-Routing.
- Re-Positioning Anti-surge Tap off- Point.
- Slowing Compressor Speed during Coast down.
- Discharge Side Gas Flaring.
- Hot Gas Recycle Valve Installation.
What is the probable cause of compressor surging?
When the flow reverses, energy and pressure at point (3) is relieved and drops down. Now the compressor can compress fluid, which
it does and with the increase of pressure the backflow occurs again
and this is the reason why compressor surge is a cyclic phenomenon.
What is meant by surging in compressor?
Compressor surge is a
form of aerodynamic instability in
axial compressors or centrifugal compressors. The term describes violent air flow oscillating in the axial direction of a compressor, which indicates the axial component of fluid velocity varies periodically and may even become negative.
What are the damages due to compressor surge?
A compressor surge can lead to the unit malfunctioning, including rapid flow reversals and changes in axial thrust,
high vibration and damage to rotor seals and bearings
, which could necessitate equipment replacement.
What is surging and stalling?
In elementary terms, stall is
a disturbance of the flow in the tangential direction
, while surge is a disturbance in the axial direction. During stalled operation, the average flow rate through the compressor is steady, but during surge, the flow rate will pulse—sometimes so violently that reversed flow is induced.
What is the purpose of the compressor surge valve?
These valves detect when
a process compression stage is approaching to surge and subsequently take action to reverse the movement of the operating point towards the surge line
. This decreases the plenum pressure and increases the flow through the compressor, resulting in stable working conditions.
What is surging cycle?
Surging occurs
when flow through the compressor falls to a critical value so that a momentary reversal of flow occurs
. This reversal of flow tends to lower the discharge pressure and normal flow resumes. The surge cycle is then repeated.
How do you control a surge?
Methods for controlling hydraulic surges include utilizing
a gas-loaded surge relief valve
, spring-loaded pressure safety valves, pilot-operated valves, surge suppressors, and rupture disks.
How do you detect a compressor surge?
Generally, the occurrence of surge is inferred from a rapid change in any measurement that is a direct function of compressor flow or head. As mentioned previously,
compressor flow, discharge pressure, and inlet temperature
are signals that can be used for surge detection.
Why does a centrifugal compressor surge?
At stalled flow condition the gas flow is zero momentarily so there is
zero pressure developed
and the compressor pressure collapses. … Now the pressure in the discharge piping is much higher than the pressure inside the compressor so the gas flow SURGES back through the compressor.
How do you stop a compressor from choking?
To prevent the compressor from operating in choke region, one can maintain the minimum flow resistance to the fluid flow by
providing Anti-choke valves at discharge
which closes to restrict the flow and hence prevents choking.
What is surge effect?
A power surge is
an abnormally high voltage lasting for a short period of time
. A power surge is a transient wave of voltage, current or power in an electrical circuit. … A surge can range from five to ten volts when a hair dryer is turned on or several thousand volts when a lightning strikes a transformer.
What is Surge test in compressor?
A compressor undergoes surge testing
to optimize the calibration of anti-surge control systems
so that they fully protect a compressor from potentially damaging surge conditions while maximizing the compressor’s turndown (operating range).
What is a positive displacement compressor?
Positive displacement compressors
In positive displacement compression,
atmospheric air is drawn into one or more of its compression chambers
, which are then closed from the inlet. As the volume of each chamber decreases, the air is compressed internally until the pressure reaches the designed build-in pressure ratio.
