Axial compressors casings

Figure 4-15. Axial compressor with fixed stator blades, double-casing design, and forged monoblock rotor. Particularly suitable for compressing nitrous gases. There are no dead spaces provoking buildup of ammonium nitrate salt.

Figure 4-16. Axial compressor with adjustable stator blades, either partially or on all stages. Double-casing design and forged monoblock rotor. This design offers a wide operating range especially in combination with speed control.

The balance chamber leakoff line, while recommended to be held within the confines of the compressor casing may well turn out to require some user piping. There are some situations where the desire for keeping open space around the compressor for maintenance may require compromise on the part of the user. The balance of the connections on the axial are for lube oil and other auxiliary equipment not different from that found on other compressors. 

Axial compressors offer a high volume capability in a relatively compact case. As can be said for any of the dynamic compressors, when properly applied, it can be a very reliable compressor. The compressor... 

Centrifugal compressor cases are classified as horizontally split or vertically split (Figures 12-40A-C). The 5th Edition, April, 1988, API Standard 617 refers to the horizontally split style as Axial Split and vertically split units as Radial Split The first terminology is more standard than that of the API-617. Figure 12-40D illustrates one flow arrangement for back-to-back internal flow, with the following advantages ... 

For high demand compression duties, the overall compression can be broken down into stages and different types of compressor used in the different casings. For example, a large flowrate with a large pressure differential might use an axial compressor followed by a centrifugal compressor. 

Compressor machines are used to increase the pressure of a gas by mechanically reducing its volume within its case. Air is most frequently compressed, but natural gas, oxygen, and nitrogen are also compressed Positive-displacement, centrifugal, and axial compressors are the three most common types used in process facilities and pipeline stations. They can handle large volumes of gas in relatively small equipment and may have a variety of drives (e.g., elearic motors and steam or gas turbines). 

This definition of efficiency does not consider the work done on the shaft driving the compressor. To bring this in we should also consider the mechanical efficiency which takes into account the friction in the bearings, or between the rotors and the outer casing (if any). In the case of centrifugal and axial compressors, this is very high, almost certainly over 98%. We can then say that... 

Mechanical Impulse The principle of mechanical impulse when applied to fluids is usually combined with one of the other means of imparting motion. As mentioned earher, this is the case in axial-flow compressors and pumps. The turbine or regenerative-type pump is another device which functions partially oy mechanical impulse. 

Small standby power turbines less than 2-MW. The smaller size of these turbines in many cases have centrifugal compressors driven by radial inflow turbines, the larger units in this range are usually axial... 

The same water tunnel was used for tests to study the effect of casing treatment in axial-flow compressors. In this study, the same Reynolds number and specific speeds were maintained as those experienced in an actual axial-flow compressor. 

Boyce. M.P., Schiller, R.N., and Desai, A.R., Study of Casing Treatment Effects in Axial-flow Compressors, ASME Paper No. 74-GT-89. 

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