# Application Range of Variety of Compressors and Compressor Selection

When I was involved in pre-FEED of well production and gas treatment, one of key deliverable is compressor studyIn this post, I want to share you about application range of variety of compressors (reciprocating, compressor, and axial-flow). In addition, I will also share the differences between those compressors.

### Application Range of Variety of Compressors

Figure below can estimate application range of variety of compressors. It is a function of inlet flow in actual cubic feet per minute and discharge pressure in psia.

### Differences Between Compressor Types

Compressor used widely in industry are reciprocating, centrifugal, and axial-flow. Rotary compressors are sometimes used for special purpose. Table below shows differences between those compressor types.

CriteriaReciprocating compressorCentrifugal compressorAxial-flow compressor
ApplicationLow-flow, high pressure service
Flow range10-5000 acfm (inlet)500-200,000 acfm (inlet)75,000-600,000 acfm (inlet)
Pressure range60,000 psia for small machine. 3000 psia for large machine10,000 psia for small machine. 100 psia for large machine10-100 psia
Pressure ratioMax 3:1 to 4:1 per stage
Mechanical design limit350-450 deg F or lower400-450 deg F600 F

Performance of centrifugal compressor and axial-flow compressor is usually expressed in polytropic efficiency. Polytropic efficiency is often considered as small stage efficiency or hydraulic efficiency. The value is higher than adiabatic efficiency.

A centrifugal or axial-flow compressor is usually designed to operate at its highest efficiency at the design flow rate. The operating range of centrifugal compressor at fixed speed is ranging from 50% to 100% design flow. The bottom end of this range is set by surge point. Range of operation actually can be varied by using variable speed drive.

As for axial-flow compressor, operating range is narrower because the surge point is at 85% to 95% design flow.

Check my previous post about how to calculate centrifugal compressor power.

Reference:

• What Process Engineers Need to Know about Compressors – William Dimoplon
• Rule of Thumbs for Chemical Engineers – Branan
• Perry’s Chemical Engineers’ Handbook