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2004 | Buch

Process Centrifugal Compressors

Basics, Function, Operation, Design, Application

verfasst von: Dipl.-Ing. Klaus H. Lüdtke

Verlag: Springer Berlin Heidelberg

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Über dieses Buch

Throughout the last decades, centrifugal compressor research and development have been revolutionized. Computational fluid dynamics have provided a better understanding of the flow and physical phenomena, and the design of new cen­ trifugal compressor components has been transformed from an "art" into a "sci­ ence". New materials and manufacturing techniques now create new geometries that could only be dreamed of in the past, and new challenging applications have pushed the limits beyond what was considered the state of the art. This new book presenting a comprehensive look at industrial compressors is therefore very timely. Readers will find a large amount of information based on extensive experience, a clear and well-founded approach to real-gas handling and solutions to many practical problems. It will provide engineering contractors and users of industrial compressors with a better insight into the "how" and "why" of different design features thus allowing a more profound basis for discussions with manufacturers. It will also cast a light on the day-by-day design practice to academia by revealing the limitations and requirements of practical applications and economics. This book combines a strict mathematical approach with practical experience and is illustrated with many examples. It fills in the gap between academic text­ books and encyclopaedic descriptions of industrial compressors. I have no doubt that this book, based on several decades of experience in the industry, both in the USA and Europe, will be well received by the centrifugal compressor community.

Inhaltsverzeichnis

Frontmatter
1. Basic Compressor Aero-Thermodynamics
Abstract
Late in the 19th century a French genius, Professor Auguste Rateau, invented the centrifugal compressor. By 1899 he had a single-stage prototype on his test stand compressing 0.5 m3/s of atmospheric air to a discharge pressure of 1.5 bar (absolute) at a rotational speed of 20,000 rpm (Engeda 1998). In 1903 he had his first industrial unit operating in a steel works and by 1905 he had built the first fivestage single-shaft centrifugal compressor delivering 0.7 m3/s of air with a 1.45: 1 pressure ratio.
Klaus H. Lüdtke
2. Thermodynamics of Real Gases
Abstract
Although the pertinent formulae for the compressibility factor, the polytropic volume and temperature exponent were published in the 1940s, the message has, even today, not reached all engineering contractors that different exponents for calculating head and temperature have to replace the traditional “ratio of specific heats”, which is irrelevant for real process gases. In this chapter a systematic derivation and compilation of real-gas thermodynamics and the most common real-gas equations of state are presented along with the ready-to-use formulae with the purpose of establishing precise descriptions of the physical relationships and avoiding misunderstandings still widespread in the turbomachinery community.
Klaus H. Lüdtke
3. Aero Components — Function and Features
Abstract
At least ten components with distinct functions make up the complete flow channel within the compressor, Fig. 1.8. The primary component responsible for the energy transfer is the impeller, and the stationary components serve the purpose of supplying the flow to the impeller or processing the flow leaving the impeller.
Klaus H. Lüdtke
4. Compressor Design Constraints
Abstract
A word of caution is required before proceeding further: since the design limitations disclosed in this chapter, stem from the accumulated knowledge and practical experience of just one compressor manufacturer, they cannot be widely generalized. The differences of geometric impeller variants, for instance, will certainly lead to different tip-speed limits and diverse statements on the maximum number of impellers per rotor. Or other OEMs may have developed impellers with higher and lower flow coefficients or may simply have larger impeller outer diameters in their spectrum of frame sizes. In many aspects, however, the market has had quite a normative effect, as far as design limits are concerned: in some written or unwritten specifications rotational speeds above 15,000 rpm, or impeller-eye Mach numbers in excess of 0.85, or stage heads above 35 kJ/kg will not be accepted (without saying why). So, in a way, the market overrules some of the individual OEMs own limits, thus generalizing the technological constraints the various manufacturers have come up with on their own. With these exceptions in mind the following constraints ought to be regarded as subjective and should not be absolutized.
Klaus H. Lüdtke
5. Compressor Off-Design Operation
Abstract
This chapter contains a methodical description and comparison of the five regulation modes: variable speed, suction throttling, adjustable inlet guide vanes, adjustable diffuser vanes and cooled bypassing. Two more topics are discussed. First, there is the test deducted dimensionless performance curve, showing work input factor versus exit flow coefficient, remaining (nearly) invariant by any transformations of speed, temperature and even gas composition. Second, there is the publication of test results in the expansion mode, i.e. the operation of a compressor stage beyond its choke point.
Klaus H. Lüdtke
6. Aerodynamic Compressor Design: Case Study
Abstract
“Design” in the industry means to size a compressor after the receipt of an order according to a philosophy with proven components. Computational fluid dynamics (CFD) is not normally applied for these routine designs on a contract basis. CFD is extensively used during the development phase of new components, which is not within the scope of this book.
Klaus H. Lüdtke
7. Application Examples
Abstract
Low capital and low operating costs and high operational flexibility — these are the usual expectations the compressor user has when sending out enquiries to process compressor manufacturers. Operational flexibility is the ability of the compressor to cope with changing external conditions such as volume flow, pressure ratio, suction temperature and gas composition, as is frequently the case in the oil and gas industry. Needless to say, availability is just as essential. However, since this, for the most part, involves the reliability of bearings, shaft seals, couplings and gear boxes, it is outside the (aerodynamic) scope of this book. The only parameter that may reduce availability is the (excessive) rotational speed that is specified by the aerodynamic design results.
Klaus H. Lüdtke
8. Improving Efficiency and Operating Range
Abstract
Since energy consumption and operational flexibility have a high priority, revolutionary inventions and evolutionary improvements have been continuously introduced over the last 100 years to enhance compressor aero-thermodynamics in order to increase both the efficiency and operating range of multistage single-shaft centrifugal compressors. This is especially so in the hydrocarbon processing industry, where such compressors are predominantly used.1
Klaus H. Lüdtke
9. Rerate of Process Centrifugal Compressors
Abstract
Quite a number of users wish to increase production as early as 3, or as late as 30 years after commissioning their plant, even if they did not envision such an extension at the time of the initial design. Two questions are almost inevitable:
1.
Can the compressor be uprated without replacing the casing, its connecting pipework and auxiliary equipment?
 
2.
Can the exchange of parts be accomplished during one of the short normal planned shutdowns?
 
Klaus H. Lüdtke
10. Standardization of Compressor Components
Abstract
Process centrifugal compressors of the single-shaft type are characterized by an almost infinite number of variation options. They compress gases with molar masses of between 2 and 100, covering volume flows within the range of 0.1 to 200 m3/s and discharge pressures from below atmosphere to 800 bar, many with side streams or extractions. From one impeller up to 25 impellers are arranged in-line or back-to-back in up to four casings. Compressors are either uncooled or have a maximum of three intercoolers per casing, resulting in a maximum number of eight nozzles per casing. Process compressors are driven by electric motors, steam or gas turbines either directly or via a gear box between the drive and compressor or between the casings.
Klaus H. Lüdtke
Backmatter
Metadaten
Titel
Process Centrifugal Compressors
verfasst von
Dipl.-Ing. Klaus H. Lüdtke
Copyright-Jahr
2004
Verlag
Springer Berlin Heidelberg
Electronic ISBN
978-3-662-09449-5
Print ISBN
978-3-642-07330-4
DOI
https://doi.org/10.1007/978-3-662-09449-5