Centrifugal compressor start-up procedures for young technical engineers. It describes some special topics in detail. Let’s start by pointing out that machines are sized based on volumetric flow and the process is measured as mass or weight flow. Capacity is the quantity (i.e., the weight or mass flow) of gas actually delivered to the process when operating between the specified inlet and discharge pressures. For a Main Air Compressor in an air separation plant, the gas is stated as dry delivered flow (or usable mass flow). This is necessary since the moisture present in the air is removed by adsorption before the air is introduced to the process cold boxes. Capacity Control Systems Plant control systems generally measure dry delivered flow to the process in ‘normal meters cubed per hour or ‘standard cubic feet per hour. Using these units as a basis, plant operators are able to keep process flows to the plant constant as the site barometric pressure and daily temperature change. Manufacturers design compressors as a function of inlet conditions. This method ensures that the size of compression components matches the specific location and process conditions to ensure adequate process flow. Capacity GLOBAL EXAMPLE A centrifugal compressor will contain larger components for a plant located in Vanderbijl Park, South Africa (which has an elevation of 1370 meters and an atmospheric site pressure of 0.860 bar) or Avezanno (which has an elevation of 735 meters and an atmospheric site pressure of 0.930 bar), than in Ellesmere Port (which is at sea level, with an inlet pressure of 1.013 bar). This is because you need a larger inlet to pass the same delivered (mass) flow of gas when the inlet pressure is 0.860 or 0.930 bar than when it is 1.013 bar. Capacity U.S. EXAMPLE A centrifugal compressor will contain larger components for a plant located in Denver, Colorado (which has an elevation of 5280 ft) and an atmospheric site pressure of 12 psi) than in Allentown, Pennsylvania (which has an elevation of 380 ft and an inlet pressure of 14.5 psi). This is because you need a larger inlet to pass the same delivered (mass) flow of gas when the inlet pressure is 12 psi than when it is 14.5 psi. Now, let’s clarify inlet flow and process flow units. Flow im3/h Inlet meters cubed per hour ICFM Inlet cubic feet per minute When the flow is based on the pressure, temperature, gas composition, and moisture content existing at the compressor inlet, it is expressed as ‘inlet meters cubed per hour’ (‘inlet cubic feet per minute). Note that ‘meters cubed’ and ‘cubic feet are both volume measurements. Convention makes one state each differently. Capacity Seal Leakage am3/h Actual meters cubed per hour ACFM Actual cubic feet per minute If seal leakage has been subtracted from this number, it is then expressed as ‘actual meters cubed per hour’ (‘actual cubic feet per minute). Please note, however, that seal leakage is generally a small number and is

1. Produced by the Global EH&S and Technical Training Team
Compressors, Centr-Basic
Operation
Qualification Number – 50114754

2. CompressorsCentr-BasicOperationScriptR5.ppt Copyright 2001, Air Products and Chemicals, Inc. (Company Confidential)
2
Overview
Centrifugal Compressor
 Starting
 Operating
 Monitoring
 Shutting Down
2

3. CompressorsCentr-BasicOperationScriptR5.ppt Copyright 2001, Air Products and Chemicals, Inc. (Company Confidential)
3
Objectives
Upon successful completion of training, each
participant should be familiar with general start-up,
operation and shut down procedures for a centrifugal
compressor.
PLEASE NOTE:
Only authorized persons can operate
centrifugal compressors. This course does not
authorize an individual to operate centrifugal
compressors.
3

4. CompressorsCentr-BasicOperationScriptR5.ppt Copyright 2001, Air Products and Chemicals, Inc. (Company Confidential)
4
Starting a Centrifugal Compressor
 Pre-Start Checks
 Process Checks
 Compressor Start-Up

5. CompressorsCentr-BasicOperationScriptR5.ppt Copyright 2001, Air Products and Chemicals, Inc. (Company Confidential)
5
Pre-Start Actions
 Establish Instrument Air
 Establish Cooling Water
 Establish Seal Gas (If
Required)
 Establish Lube Oil
 General Process Checks
 Permissives Satisfied

6. CompressorsCentr-BasicOperationScriptR5.ppt Copyright 2001, Air Products and Chemicals, Inc. (Company Confidential)
6
Establish Instrument Air

7. CompressorsCentr-BasicOperationScriptR5.ppt Copyright 2001, Air Products and Chemicals, Inc. (Company Confidential)
7
Establish Cooling Water

8. CompressorsCentr-BasicOperationScriptR5.ppt Copyright 2001, Air Products and Chemicals, Inc. (Company Confidential)
8
Establish Seal Gas

9. CompressorsCentr-BasicOperationScriptR5.ppt Copyright 2001, Air Products and Chemicals, Inc. (Company Confidential)
9
Establish Lube Oil
 Reservoir Level
 Oil Temperature
 Gearbox Vacuum
 Oil Pressure

10. CompressorsCentr-BasicOperationScriptR5.ppt Copyright 2001, Air Products and Chemicals, Inc. (Company Confidential)
10
Process Checks
 Inlet Control Device
Closed
 Vent or Recycle Valve
Opened
 Vibration on Bypass

11. CompressorsCentr-BasicOperationScriptR5.ppt Copyright 2001, Air Products and Chemicals, Inc. (Company Confidential)
11
Permissives Satisfied
 All shutdown Interlocks
Cleared
 Oil Pressure Satisfied
 Switch Gear Engaged
 Circuit Breaker Control
Switch and Motor
Charging Switch in the
‘On” Position
 Clear Motor Control
Center

12. CompressorsCentr-BasicOperationScriptR5.ppt Copyright 2001, Air Products and Chemicals, Inc. (Company Confidential)
12
Centrifugal Compressor Start-Up
 Start
 Switch Vibration Off By-
Bypass
 Switch Auxiliary Oil
Pump Off

13. CompressorsCentr-BasicOperationScriptR5.ppt Copyright 2001, Air Products and Chemicals, Inc. (Company Confidential)
13
Operating a Centrifugal Compressor
Air Products &
Chemicals, Inc:

14. CompressorsCentr-BasicOperationScriptR5.ppt Copyright 2001, Air Products and Chemicals, Inc. (Company Confidential)
14
Compressor Performance Curve

15. CompressorsCentr-BasicOperationScriptR5.ppt Copyright 2001, Air Products and Chemicals, Inc. (Company Confidential)
15
CONTINUE WITH SAME SLIDE

16. CompressorsCentr-BasicOperationScriptR5.ppt Copyright 2001, Air Products and Chemicals, Inc. (Company Confidential)
16
Typical Compressor Flow Control
Circuit
Compressor
Vent
Valve
Electric Signal to Programmable
Electronic Control System Instrument
Air
Inlet
Control
Device
I/P
I/P
Feed Flow
Check Valve
Flow
device

17. CompressorsCentr-BasicOperationScriptR5.ppt Copyright 2001, Air Products and Chemicals, Inc. (Company Confidential)
17
CONTINUE WITH SAME SLIDE

18. CompressorsCentr-BasicOperationScriptR5.ppt Copyright 2001, Air Products and Chemicals, Inc. (Company Confidential)
18
Typical Compressor Recycle Control
Circuit
Compressor
Recycle
Valve
Electric Signal to Programmable
Control System Instrument
Air
Inlet
Control
Device
Isolation
Valve
I/P
I/P
Process
Check Valve

19. CompressorsCentr-BasicOperationScriptR5.ppt Copyright 2001, Air Products and Chemicals, Inc. (Company Confidential)
19
Loading
 Open Inlet Control
Device
 Close Vent or Recycle
Valve

20. CompressorsCentr-BasicOperationScriptR5.ppt Copyright 2001, Air Products and Chemicals, Inc. (Company Confidential)
20
Monitoring
 Alarms
 Vibration
 Motor Bearing Temperature
 Motor Winding Temperature
 Motor Current
 Seal Gas
 Cooler Approach Temperatures
 Oil Temperature
 Oil Pressure
 Gearbox Vacuum

21. CompressorsCentr-BasicOperationScriptR5.ppt Copyright 2001, Air Products and Chemicals, Inc. (Company Confidential)
21
Centrifugal Compressor Shut Down
 Unload Machine
 Stop
 Ensure Auxiliary Oil
Pump is Running

22. CompressorsCentr-BasicOperationScriptR5.ppt Copyright 2001, Air Products and Chemicals, Inc. (Company Confidential)
22
COMPETENCY EVALUATION
(No Corresponding Slide)

23. CompressorsCentr-BasicOperationScriptR5.ppt Copyright 2001, Air Products and Chemicals, Inc. (Company Confidential)
23
Participant’s Feedback
(No Corresponding Slide)

24. CompressorsCentr-BasicOperationScriptR5.ppt Copyright 2001, Air Products and Chemicals, Inc. (Company Confidential)
24
Participant’s Feedback
(No Corresponding Slide)