This document discusses four methods of surge control for centrifugal compressors: 1) controlling surge with a simple minimum flow cold bypass between the discharge and suction sides; 2) controlling surge by altering compressor speed to meet discharge pressure requirements; 3) controlling surge by altering inlet guide vanes or compressor speed to reset cold bypass flow; 4) controlling surge by correlating differential pressure across the compressor to reset minimum cold bypass flow.

1. Surge Control with Simple Minimum Flow Cold Bypass
between Discharge & Suction Side
KO Drum
Suction Block
Valve
Anti-Surge
Valve (ASV)
Compressor
Driver
FT
Cooler
FIC
Surge Control with Suction Flow Altering /Resetting
Compressor Speed to Meet Discharge Pressure Requirements
KO Drum
Suction Block
Valve
Anti-Surge
Valve (ASV)
Compressor
Driver
FIC
SC
Cooler
FT
Surge Control with Speed/ Inlet Guide Vane (IGV) Alters/Resets
the Cold Flow Bypass
KO Drum
Suction Block
Valve
Anti-Surge
Valve (ASV)
Compressor
Driver
FIC
SC
Cooler
FT
Speed SC) / Inlet
Guide Vane (IGV)
(ZT)
Differential pressure (DP) across the Compressor Suction & Discharge is
used to correlate DP vs. Flow to Alter/Reset the Minimum Flow Cold Bypass
KO Drum
Suction Block
Valve
Anti-Surge
Valve (ASV)
Compressor
Driver
FIC
Cooler
FT
FY
Set Kh
DP
VARIOUS METHODS OF CENTRIFUGAL COMPRESSOR SURGE CONTROL