Figure-x.x Thomassen-Elliott centrifugal compressor, barrel type
Figure-x.x Impeller 3

Turbomachinery using centrifugal compressors

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Standards

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As turbomachinery became more common, standards have been created to guide manufacturers to assure end-users that their products meet minimum safety and performance requirements. Associations formed to codify these standards relying on manufacturers, end-users, and related technical specialists. A partial list of these associations and their standards are listed below:

Gas Turbines

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Figure 4.1 – Jet engine cutaway showing the centrifugal compressor and other parts.
 
Figure 4.2 – Jet engine cross section showing the centrifugal compressor and other parts.

Alternative references to Gas turbines:[6]

Figures 4.1–4.2 illustrate the general configuration of a Brayton cycle gas-turbine. Starting with compressors (using one or more compression stages) followed by a combustor followed by a turbine (using one or more expansion stages). In their simple form, modern gas turbines operate on the Brayton cycle. (ref Figure 5.1) The impeller's are open with stationary shrouds to accommodate the stresses of high rotational speed operation. The impeller's inducer uses splitters to reduce high mach number friction (improving efficiency) and increase throat area (widening the operational flow range of performance. To increase efficiency, the impeller discharge flow enters a vaned diffuser followed buy an annular duct. Features differentiating modern compressors are optimized variable inlet guide vanes, twisted: impeller, splitter, and vaned diffuser lead edges to minimize incidence losses. These achievements are possible only though CFD analysis (both direct and inverse). Compressible ideal-gas properties often work well for the design, test and analysis of centrifugal compressor performance.

Standards applied to Gas-turbine centrifugal compressors are set by the relevant civilian and military certification authorities. It is a prority to achieve the safety and durability required while in service. Centrifugal impellers used in gas turbines are commonly made from titanium alloy forgings as they require strength to operate at high speed. The impeller's blades/vanes are commonly flank milled or point milled on 5-axis milling machines. When running clearances must be minimized and there is a risk of the impeller rubbing its shroud. To eliminate this, the manufactured geometry accounts for deflections experienced by the impeller between cold-no-speed and hot-max-speed operation.

 
Figure-x.x Turbocharger Animation

Turbochargers are used to augment Otto, Diesel, Atkinson, and Miller cycle internal combustion engines.[7] Ref. Figure 1.1 These heat engines replace the combutor of, the closely related, gas-turbine. As a result, the compressor discharge annular duct is replaced with an area scheduled volute. While turbochargers are now common in automotive applications, many WWII aircraft engines used turbo-superchargers. Industrially, turbochargers are often used on large (stationary and locomotive) diesel electric generators. A unique feature of automotive turbochargers is the impeller discharges directly into the volute.

Standards set by the industry for turbochargers include the SAE.[8] Excluding hardware differences, most of what is discriptive for gas turbine centrifugal compressors applies directly to the turbo-charger. Compressible ideal-gas properties often work well for the design, test and analysis of turbocharger centrifugal compressor performance. [9]

API compressors

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Centrifugal compressors governed by the "American Petroleum Institute" standards are listed here by Wikipedia article titles.[10]

Pipeline gas-compressors of natural gas to move the gas from the production site to the consumer.[11]

Centrifugal compressors for such uses may be one- or multi-stage and driven by large gas turbines. Standards set by the industry (ISO 15156,ASME) result in thick casings to achieve a required level of safety. The impellers are often if not always of the covered style which makes them look much like pump impellers. This type of compressor is also often termed an API-style. The power needed to drive these compressors is most often in the thousands of horsepower (HP). Use of real gas properties is needed to properly design, test and analyze the performance of natural gas pipeline centrifugal compressors.


oil refineries, Natural-gas processing, petrochemical and chemical plants.[11]

Centrifugal compressors for such uses are often one-shaft multi-stage and driven by large steam or gas turbines. Their casings are termed horizontally split if the rotor is lowered in to the bottom half during assembly or barrel if it has no lengthwise split-line with the rotor being slid in. Standards set by the industry (ANSI/API, ASME) for these compressors result in thick casings to achieve a required level of safety. The impellers are often of the covered style which makes them look much like pump impellers. This type of compressor is also often termed API-style. The power needed to drive these compressors is usually in the thousands of HP. Use of real gas properties is needed to properly design, test and analyze their performance.


Air-conditioning and refrigeration and HVAC: Centrifugal compressors quite often supply the compression in water chillers cycles.[12]

Because of the wide variety of vapor compression cycles (thermodynamic cycle, thermodynamics) and the wide variety of workings gases (refrigerants), centrifugal compressors are used in a wide range of sizes and configurations. Use of real gas properties is needed to properly design, test and analyze the performance of these machines. Standards set by the industry for these compressors include ASHRAE, ASME & API.


In industry and manufacturing to supply compressed air for all types of pneumatic tools.[13]

Centrifugal compressors for such uses are often multistage and driven by electric motors. Inter-cooling is often needed between stages to control air temperature. Road-repair crews and automobile repair garages find screw compressors better adapt to their needs. Standards set by the industry for these compressors include ASME and government regulations that emphasize safety. Ideal gas relationships are often used to properly design, test and analyze the performance of these machines. Carrier's equation is often used to deal with humidity.

ASHRAE compressors

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Centrifugal compressors governed by the "American Society of Heating, Refrigeration and Air-conditioning Engineering" standards are listed here by Wikipedia article titles.


In air separation plants to manufacture purified end product gases.[13]

Centrifugal compressors for such uses are often multistage using inter-cooling to control air temperature. Standards set by the industry for these compressors include ASME and government regulations that emphasize safety. Ideal gas relationships are often used to properly design, test and analyze the performance of these machines when the working gas is air or nitrogen. Other gases require real gas properties.

  • In oil field re-injection of high pressure natural gas to improve oil recovery.[11]
    Centrifugal compressors for such uses are often one-shaft multi-stage and driven by gas turbines. With discharge pressures approaching 700 bar, casing are of the barrel style. Standards set by the industry (API, ASME) for these compressors result in large thick casings to maximize safety. The impellers are often if not always of the covered style which makes them look much like pump impellers. This type of compressor is also often termed API-style. Use of real gas properties is needed to properly design, test and analyze their performance.
  1. ^ https://www.asme.org/codes-standards/publications-information/bpvc-resources
  2. ^ https://www.asme.org/codes-standards/publications-information/performance-test-codes
  3. ^ https://www.ashrae.org/technical-resources/ashrae-handbook/description-2021-ashrae-handbook-fundamentals
  4. ^ "CAGI". www.cagi.org. Compressed Air and Gas Institute. Retrieved 13 December 2021. {{cite web}}: |first1= missing |last1= (help); Check |url= value (help)
  5. ^ https://www.iso.org/search.html?q=Centrifugal%20compressors&hPP=10&idx=all_en&p=0&hFR%5Bcategory%5D%5B0%5D=standard
  6. ^ Saravanamuttoo, H. I. H.; Rogers, G. F. C.; Cohen, H. (2001). Gas Turbine Theory. Prentice-Hall. ISBN 978-0-13-015847-5.
  7. ^ Baines, Nicholas C. (2005). Fundamentals of Turbocharging. Concepts ETI . ISBN 978-0-933283-14-5.
  8. ^ "SAE Standards". SAE/standards/power and propulsion/engines. SAE International. Retrieved 23 April 2011.
  9. ^ Cite error: The named reference Lakshminarayana was invoked but never defined (see the help page).
  10. ^ https://www.api.org/products-and-services/standards/
  11. ^ a b c API (July 2002). Std 617-2002 Axial and Centrifugal Compressors and Expander-compressors for Petroleum, Chemical and Gas Industry Services. New York: API.
  12. ^ ASHRAE, American Society of Heating, Refrigeration and Air-Conditioning Engineers. "Standards & Guidelines". ASHRAE. Retrieved 23 April 2011.{{cite web}}: CS1 maint: multiple names: authors list (link)
  13. ^ a b API (October 2007). Std 672-2007 Packaged, Integrally Geared Centrifugal Air Compressors for Petroleum, Chemical, and Gas Industry Services. New York: API.