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Compressed Air Systems
Published in Stephen A. Roosa, Steve Doty, Wayne C. Turner, Energy Management Handbook, 2020
A disadvantage of centrifugal compressors is their relatively poor part-load efficiency. Flow output must be controlled by an inlet guide vane, which is less efficient than variable-speed or on/off control that other types compressors employ. If flow falls below a certain threshold, the centrifugal compressor falls in danger of surging, which is backwards flow that could result in hardware damage including machine failure. To prevent surging, centrifugal compressors have a blow-off valve at the air discharge, which opens to atmosphere to ensure sufficient airflow during low air-demand periods. Blow-off air represents wasted energy, and causes compressor power draw to be relatively constant regardless of useful air output. A more efficient control method for centrifugal compressors is one that completely closes the inlet guide vane and unloads the compressor instead of continuously releasing air. This control method has become a common option for centrifugal compressors.
Applications
Published in Raj P. Chhabra, CRC Handbook of Thermal Engineering Second Edition, 2017
Joshua D. Ramsey, Ken Bell, Ramesh K. Shah, Bengt Sundén, Zan Wu, Clement Kleinstreuer, Zelin Xu, D. Ian Wilson, Graham T. Polley, John A. Pearce, Kenneth R. Diller, Jonathan W. Valvano, David W. Yarbrough, Moncef Krarti, John Zhai, Jan Kośny, Christian K. Bach, Ian H. Bell, Craig R. Bradshaw, Eckhard A. Groll, Abhinav Krishna, Orkan Kurtulus, Margaret M. Mathison, Bryce Shaffer, Bin Yang, Xinye Zhang, Davide Ziviani, Robert F. Boehm, Anthony F. Mills, Santanu Bandyopadhyay, Shankar Narasimhan, Donald L. Fenton, Raj M. Manglik, Sameer Khandekar, Mario F. Trujillo, Rolf D. Reitz, Milind A. Jog, Prabhat Kumar, K.P. Sandeep, Sanjiv Sinha, Krishna Valavala, Jun Ma, Pradeep Lall, Harold R. Jacobs, Mangesh Chaudhari, Amit Agrawal, Robert J. Moffat, Tadhg O’Donovan, Jungho Kim, S.A. Sherif, Alan T. McDonald, Arturo Pacheco-Vega, Gerardo Diaz, Mihir Sen, K.T. Yang, Martine Rueff, Evelyne Mauret, Pawel Wawrzyniak, Ireneusz Zbicinski, Mariia Sobulska, P.S. Ghoshdastidar, Naveen Tiwari, Rajappa Tadepalli, Raj Ganesh S. Pala, Desh Bandhu Singh, G. N. Tiwari
A centrifugal compressor can be a single-stage compressor, having only one impeller, or it can be a multistage compressor, having two or more impellers mounted in the same casing. The suction gas generally passes through a set of adjustable inlet guide vanes (prerotation vanes) or an external suction damper before it enters the rotating impeller. The guide vanes (or the suction damper) are used to control the flow rate through the compressor. The high-velocity gas discharging from the impeller enters a radial diffuser, which can have vanes or be without vanes. Diffusers with vanes are typically used in compressors designed to provide high-pressure ratios. These vanes are generally fixed, but they can also be adjustable. Adjustable diffuser vanes can be used for capacity modulation either in lieu of or in conjunction with the inlet guide vanes.
Centrifugal Compressors
Published in Ahmed F. El-Sayed, Aircraft Propulsion and Gas Turbine Engines, 2017
Centrifugal compressors are used in many industrial applications, such as refineries, chemical and petrochemical plants, natural gas processing and transmission plants, very large-scale refrigeration, and iron and steel mills. These centrifugal compressors may have single or multiple stages (up to five) and can operate at very high inlet pressures. Rolls Royce RFA36 and RFA24 giant compressors may have pressures up to 155 bar, flow rate of 200 at design speed from 3,600 to 12,800 rpm. The General Electric Power Systems, Oil and Gas, and Nuovo Pignone centrifugal compressors for re-injection services have discharge pressure up to 500 bar. Hitachi had manufactured 800 sets of centrifugal compressors since first unit delivered in 1911 to be employed in different applications. Earlier types manufactured by Hitachi in 1978 had an approximate pressure ratio of 260 for four groups CO2 applications [5]. On the other hand, centrifugal compressors are employed by PCA in its micro-gas turbine generator.
Investigation on flow mechanism of an advanced transonic centrifugal compressor with free-form impeller at design and off-design speeds
Published in Engineering Applications of Computational Fluid Mechanics, 2022
Zi-liang Li, Xin-gen Lu, Ge Han, Jun-qiang Zhu
Since the industrial revolution, the atmospheric concentration of CO2 has continued to rise and has not yet reached its peak (Ritchie & Roser, 2020), controlling greenhouse gas emissions has become a global consensus. One of the economical methods to achieve the international and national targets is to improve the efficiency of energy systems (Kuramochi et al., 2020; Lamb et al., 2021). Due to their high single-stage pressure ratio, good reliability and compact structure, centrifugal compressors are widely applied in gas turbines, turbochargers, process industries, etc. Further, the electricity or fuel consumed by them plays a major part in industrial systems. Therefore, it is necessary to improve the performance of centrifugal compressors towards greater efficiency and higher single-stage pressure ratios, which presents design challenges (Durante et al., 2017; Martinez et al., 2017; Mojaddam & Pullen, 2019).
Design of a robust LMI-based model predictive control method for surge instability in interconnected compressor systems in the presence of uncertainty and disturbance
Published in Systems Science & Control Engineering, 2021
Cong Xie, Hashem Imani Marrani
A compressor is a mechanical device that increases the pressure of a gas by reducing its volume. Centrifugal compressors, sometimes called radial compressors, are a subclass of dynamic turbo-machinery and achieve a pressure rise by adding kinetic energy/velocity to a continuous flow of fluid through the rotor or impeller (Brun & Kurz, 2018; Tibrewala et al., 2014). The most important applications of centrifugal compressors are in oil refineries, natural-gas processing, petrochemical, chemical plants, air-conditioning and refrigeration and HVAC, in industry and manufacturing to supply compressed air for all types of pneumatic tools and in air separation plants to manufacture purified and product gases (Bloch & Soares, 1998).
Feasibility of predicting performance characteristics of multi-stage centrifugal natural gas compressors, an effort on using data-mining techniques
Published in Chemical Engineering Communications, 2023
Tania Sadeghi, Iman Fakhari, Anders Andreasen, Ahmad Arabkoohsar
A centrifugal compressor is most appropriate for applications where a wide operating flow range and high reliability (Gresh 2018). Centrifugal compressors are classified as dynamic compressors, also known as turbomachines. Dynamic compressors achieve compression by applying inertial forces to the gas, such as acceleration, deceleration, and turning, using rotating impellers (Giampaolo 2010). The centrifugal compressor components are divided into several steps and divided further into the inlet stage, middle stage, and final stage. Each stage consists of an impeller and a diffuser, as depicted in Figure 1. In general, the impeller is a rotating element that adds energy and work to the gas.