6 replies to this topic

[panoska]

Hello everyone,

Could someone share any experience about controlling 2 air compressors working in parallel?

Thank you in advance! ????

[breizh]

Hi,

Consider the resource attached to support your work.

Breizh

Attached Files

•  Compressed_Air_Manual_Atlas Copco.pdf   5.91MB   9 downloads
•  Calculating Storage for Demand Events.pdf   4.14MB   9 downloads

[panoska]

Thanks for the reply.
What is the reason that it is advised to avoid 2 compressors running in parallel?

[breizh]

hi,

2 units in // for capacity and redundancy. In case of maintenance and break down you still have capacity available.

 

Breizh 

[breizh]

other documents about centrifugal compressors

Breizh

Attached Files

•  anti surge system.pdf   261.86KB   1 downloads
•  anti surge control.pdf   1.26MB   4 downloads
•  Controlling-Centrifugal-Compressors.pdf   651.33KB   3 downloads
•  CAGI_ElectHB_ch2.pdf   6.63MB   3 downloads

[panoska]

Hello Breizh,

Thanks for the documents. But, I coud not find any information on how to control 2 compressors running in parallek.

[breizh]

To me,

2 compressors running //, one should be master and the other the slave, meaning one running at fixed speed and the other on VSD to compensate.

Breizh

 

EDIT : Google search AI

 

The control philosophy for air compressors running in parallel focuses on matching the air supply with demand efficiently, maintaining a stable system pressure, and ensuring equal run-time and longevity of the compressors. This is typically achieved using master control systems (sequencers or central controllers) that coordinate the individual units. 

Key elements of the control philosophy include:

• Pressure Management: The primary objective is to maintain constant pressure in the common air header. The system uses pressure switches or transducers to monitor the demand and trigger compressor responses.
• Sequencing Control: A master controller (sequencer) automates the starting and stopping of multiple compressors in an optimized sequence based on demand levels. This ensures that only the necessary number of compressors are running to meet the current flow demand, saving energy.
• Load Balancing and Sharing: The system aims to distribute the workload evenly among the online compressors to prevent any single unit from being overloaded or overused.
  • Equal Run-Hours: The controller rotates the lead compressor role among the units to equalize their running hours, which extends the overall life of the equipment and spreads out maintenance needs.
  • Efficient Operation: The most efficient strategy is to run most of the compressors at full load, with only one unit handling the partial or "trim" load. This trim compressor should ideally have high partial load efficiency, such as a Variable Speed Drive (VSD) unit.
• Cascade Control (Basic Method): A more basic method uses staggered pressure setpoints, where each compressor has a slightly different cut-in and cut-out pressure. As pressure drops, compressors are activated sequentially. While simple, this can be less energy-efficient than a master controller because the system runs at a higher average pressure.Redundancy and Reliability: By having multiple smaller compressors in parallel instead of one large one, the system provides redundancy. If one compressor malfunctions or needs maintenance, the others can continue to supply air, minimizing downtime.System Protection:Centralized Monitoring: Modern systems often include networked controls that offer centralized monitoring and remote connectivity for better management and optimization of the entire compressed air system.