IMPORTANCE OF AUTO RECIRCULATION VALVES
For Oil Terminal / Gantry
Purpose:
An automatic recirculation valve aim is to ensure pump operation at optimum efficiency near BEP (Best Efficiency Point) and to provide effective protection for centrifugal pumps against serious damage from overheating or instability that can result from even a few minutes of no flow. This valve should automatically assure optimum flow and stable pump operation. This valve should re-circulate only minimum flow required to always assure efficient pump operation.
When main process flow requirement is high enough to ensure efficient pump operation, re-circulation flow is not required, and valve will remain closed. But as the process main flow demand decreases, re-circulation becomes necessary.
Process Description :
When there is no consumption of Oil / Petroleum Product to Truck / Lorry Filling (TLF), pilot of ARV gives full signal pressure to main valve diaphragm resulting in ARV main valve going to full open. As the main flow to the TLF increases, pilot throttles pressure to the main valve diaphragm reducing by-pass flow. When the main flow to TLF is adquate to ensure efficient pump operation, pilot gets fully closed and ARV main valve closes
As the main flow to TLF decreases, reverse action takes place and re-circulation flow increases propotionately.
Features & Advantages:
- The valve itself is completely, self contained system, i.e. it is a rec-circulating control valve and it is a pressure let down device.
- The valve is desgined and constructed in accordance with ANSI B16.34. The valve seat leakage is as per Class VI of ANSI / FCI 70.2. The face to face distance is as per ANSI B16.5.
- The Auto Re-circulation Valve has adquate flow capacity to ensure by-pass of reuired minimum flow to protect pump.
- When the main TFL flow is more than adquate to ensure efficient pump operation, the Auto Re-Circulation Valve closes the by-pass flow fully and at the same time, it does not offer any restriction / friction / pressure loss to main flow.
- The Auto Re-circulation Valve has contineously adjustable range to adjust Auto Re-circulation point without removing the valve from line so as to achieve
a. efficient pump operation
b. desired pump discharge pressure.
The Auto Re-circulation Valve has following optional provision:
a) It can receive 4-20 mA input signal from DCS / PLC / SCADA corresponding to flow requirement and automatically adjust necessary Re-circulation flow based on the same.
b) In case of the failure of the input signal, the Auto Re-circulation Valve automatically changes over to its self regulating mode.