Centrifugal Compressor Polytropic Performance Evaluation Using Cubic Polynomial Approximation for the Temperature-Entropy Polytropic Path

2021 ◽  
Author(s):  
Matt Taher ◽  
B. F. Evans
Keyword(s):  
Performance Evaluation ◽  
High Precision ◽  
Centrifugal Compressor ◽  
Approximation Method ◽  
Performance Testing ◽  
Ease Of Use ◽  
Continuous Path ◽  
State Variables ◽  
Cubic Polynomial ◽  
Compressor Performance

Abstract A highly accurate centrifugal compressor polytropic performance approximation method has been developed that is easy to employ. The method is based upon a constant efficiency, temperature-entropy path for real gases. The elegance of this method is its exceedingly simple way of calculating polytropic efficiency with sufficiently high precision as required for compressor performance testing. A constant efficiency polytropic path can be modeled as either a single or several sequential cubic polynomial segments affording solutions that allow for determining thermodynamic state variables along a continuous path. New analytic terms have been developed for slope and curvature of temperature versus entropy along the constant efficiency polytropic path. A broad range of example case results verify the accuracy and ease of use of the method.

On-Line Monitoring Software and Diagnostic Tool for Centrifugal Compressor Performance Evaluation

2006 ◽  
Author(s):  
Kamorudeen B. Abidogun ◽  
Mohamed S. Al-Ghamdi ◽  
Adel Al-Ali ◽  
Khalid Al-Yousef
Keyword(s):  
Performance Evaluation ◽  
Performance Analysis ◽  
Centrifugal Compressor ◽  
Intelligent System ◽  
Accumulation Rate ◽  
Gas Analysis ◽  
Actual Performance ◽  
Process Gas ◽  
Performance Deterioration ◽  
Compressor Performance

In-house developed centrifugal compressor performance software was customized for PETROKEMYA (an affiliate of SABIC) Olefins III cracked gas compressor (CGC), the heart of ethylene plant. The software provides live performance analysis of the machine by calculating, per section, polytropic efficiency, polytropic head, and gas power using Lee-Kesler equation of state. Gas analysis is read online to reflect the minute changes in the composition on the calculated parameters. Actual operating parameters are plotted continuously and compared to the performance curves in order to predict possible performance deterioration before it becomes too late. Such information is useful in determining future maintenance requirements based on the actual performance of the machine rather than the traditional time-based maintenance. Moreover, it ensures proper timely action through optimization of wash oil or other chemical injection to help minimize fouling accumulation rate and maximize production and machine availability. Features are introduced to enable performance analysis of the compressor since commissioning to be carried out by click of a button, providing useful information for upgrading and troubleshooting. Unlike its commercially available counterpart with write-protected restrictions, the software is easily modified for additional features that are of interest to Engineers. Features planned for the future include adding intelligent system capability for predicting performance deterioration severity, auto-notifying agents etc. Performance evaluation of a 45 MW, five section process gas compressor before and after turnaround (T/A), clearly revealed the fouling prediction capability of the software.

scholarly journals Centrifugal Compressor Polytropic Performance—Improved Rapid Calculation Results—Cubic Polynomial Methods

2021 ◽  
Vol 6 (2) ◽  
pp. 15
Author(s):  
Matt Taher ◽  
Fred Evans
Keyword(s):  
Performance Test ◽  
Ease Of Use ◽  
Solution Technique ◽  
Test Duration ◽  
Calculation Results ◽  
Cubic Polynomial ◽  
Compressor Performance ◽  
Cubic Polynomials ◽  
Slope Constraints ◽  
Polynomial Methods

This paper presents a new improved approach to calculation of polytropic performance of centrifugal compressors. This rapid solution technique is based upon a constant efficiency, temperature-entropy polytropic path represented by cubic polynomials. New thermodynamic path slope constraints have been developed that yield highly accurate results while requiring fewer computing resources and reducing computing elapsed time. Applying this thermodynamically sound cubic polynomial model would improve accuracy and shorten compressor performance test duration at a vendor’s shop. A broad range of example case results verify the accuracy and ease of use of the method. The example cases confirm the cubic polynomial methods result in lower calculation uncertainty than other methods.

scholarly journals Accuracy Expectations for Gas Turbine and Centrifugal Compressor Performance Testing

1982 ◽  
Author(s):  
T. C. Heard ◽  
E. J. Hipp
Keyword(s):  
Gas Turbine ◽  
Centrifugal Compressor ◽  
Measurement Errors ◽  
Simple Procedure ◽  
Performance Testing ◽  
Reading Errors ◽  
Actual Equipment ◽  
Engineering Statistics ◽  
Compressor Performance ◽  
Gas Turbine Compressor

Engineers inexperienced with testing or interpretation of test results from gas turbine/centrifugal compressor sets may not be familiar with the uncertainties stemming from measuring instrument and reading errors. This may be because only a few specialists are acquainted with the applicable engineering statistics and acceptable measurement accuracy levels, but it is also probably due to the unavailability of clear, simply worded documentation of the principles involved. Because there are significant uncertainties in power and specific fuel consumption results of such tests, it is important for concerned engineers to recognize and to develop a sensitivity for the various measurement errors and to take them into account when judging the actual equipment performance. This paper outlines a simple procedure for estimating instrument errors and for assessing their influences on the final results. In addition it illustrates justifiable accuracy expectations of gas turbine/compressor system tests and it may be a starting reference for those interested in the subject.

Mathematical Modeling of the Polytropic Process Using the Sequential Cubic Polynomial Approximation

2021 ◽  
Author(s):  
Matt Taher
Keyword(s):  
Performance Testing ◽  
Operating Conditions ◽  
Solution Technique ◽  
Polynomial Method ◽  
Compression Process ◽  
Energy Degradation ◽  
Cubic Polynomial ◽  
Compressor Performance ◽  
Path Dependent ◽  
Polytropic Process

Abstract The polytropic process is used to signify the effect of “energy degradation” associated with the equipment losses, which is as an inherent irreversibility in a compression process. The polytropic process is path dependent, which entails the irreversibility associated with the system. The change of gas composition and operating conditions affect the energy degradation. In this paper the polytropic process of real gas is explained and thermodynamics and mathematical model used in Taher-Evans Cubic Polynomial Method [1], [2] is presented. The elegance of Taher-Evans Cubic Polynomial Method is its rapid solution technique and high precision for calculating polytropic efficiency as required for compressor performance testing by the ASME PTC-10 [3].

Effects of Diffuser Vane Geometries on Compressor Performance and Noise Characteristics in a Centrifugal Compressor

2013 ◽  
Author(s):  
Yohei Morita ◽  
Nobumichi Fujisawa ◽  
Takashi Goto ◽  
Yutaka Ohta
Keyword(s):  
Centrifugal Compressor ◽  
Noise Level ◽  
Leading Edge ◽  
Broadband Noise ◽  
Frequency Noise ◽  
Numerical Techniques ◽  
Vaned Diffuser ◽  
Noise Characteristics ◽  
Edge Vortex ◽  
Compressor Performance

The effects of the diffuser vane geometries on the compressor performance and noise characteristics of a centrifugal compressor equipped with vaned diffusers were investigated by experiments and numerical techniques. Because we were focusing attention on the geometries of the diffuser vane’s leading edge, diffuser vanes with various leading edge geometries were installed in a vaned diffuser. A tapered diffuser vane with the tapered portion near the leading edge of the diffuser’s hub-side could remarkably reduce both the discrete frequency noise level and broadband noise level. In particular, a hub-side tapered diffuser vane with a taper on only the hub-side could suppress the development of the leading edge vortex (LEV) near the shroud side of the diffuser vane and effectively enhanced the compressor performance.

Parametric Studies of Pipe Diffuser on Performance of a Highly Loaded Centrifugal Compressor

2014 ◽  
Vol 136 (12) ◽  
Author(s):  
Ge Han ◽  
Xingen Lu ◽  
Shengfeng Zhao ◽  
Chengwu Yang ◽  
Junqiang Zhu
Keyword(s):  
Centrifugal Compressor ◽  
Performance Enhancement ◽  
Detailed Comparison ◽  
Flow Distortion ◽  
Flow Solver ◽  
Beneficial Effects ◽  
Physical Mechanisms ◽  
Parametric Studies ◽  
Compressor Performance ◽  
Highly Loaded

Pipe diffusers with several different geometries were designed for a highly loaded centrifugal compressor originally using a wedge diffuser. Parametric studies on the effect of pipe diffuser performance of a highly loaded centrifugal compressor by varying pipe diffuser inlet-to-impeller exit radius ratio, throat length, divergence angle, and throat area on centrifugal compressor performance were performed using a state-of-the-art multiblock flow solver. An optimum design of pipe diffuser was obtained from the parametric study, and the numerical results indicate that this pipe diffuser has remarkable advantageous effects on the compressor performance. Furthermore, a detailed comparison of flow visualization between the pipe diffuser and the wedge diffuser was conducted to identify the physical mechanism that account for the beneficial effects of the pipe diffuser on the performance and stability of the compressor. It was found that the performance enhancement afforded by the pipe diffuser is a result of the unique diffuse inlet flow pattern. Alleviating flow distortion in the diffuser inlet and reducing the possibility of a flow separation in discrete passages are the physical mechanisms responsible for improving the highly loaded centrifugal compressor performance.

Effect of Different Geometrical Inlet Pipes on a High Speed Centrifugal Compressor

2013 ◽  
Author(s):  
Ce Yang ◽  
Ben Zhao ◽  
C. C. Ma ◽  
Dazhong Lao ◽  
Mi Zhou
Keyword(s):  
Centrifugal Compressor ◽  
High Speed ◽  
Pressure Ratio ◽  
Inlet Pipe ◽  
Unsteady Pressure ◽  
Bent Pipe ◽  
Low Mass ◽  
Compressor Performance ◽  
Spectral Frequency ◽  
The One

Two different inlet configurations, including a straight pipe and a bent pipe, were experimentally tested and numerically simulated using a high-speed, low-mass flow centrifugal compressor. The pressure ratios of the compressor with the two inlet configurations were tested and then compared to illustrate the effect of the bent inlet pipe on the compressor. Furthermore, different circumferential positions of the bent inlet pipe relative to the volute are discussed for two purposes. One purpose is to describe the changes in the compressor performance that result from altering the circumferential position of the bent inlet pipe relative to the volute. This change in performance may be the so-called clocking effect, and its mechanism is different from the one in multistage turbomachinery. The other purpose is to investigate the unsteady flow for different matching states of the bent inlet pipe and volute. Thus, the frequency spectrum of unsteady pressure fluctuation was applied to analyze the aerodynamic response. Compared with the straight inlet pipe, the experimental results show that the pressure ratio is modulated and that the choke point is shifted in the bent inlet pipe. Similarly, the pressure ratio can be influenced by altering the circumferential position of the bent inlet pipe relative to the volute, which may have an effect on the unsteady pressure in the rotor section. Therefore, the magnitude of interest spectral frequency is significantly changed by clocking the bent inlet pipe.

Numerical Analysis of Deposits and Corrosion Influence on a Centrifugal Compressor Performance

2012 ◽  
Author(s):  
Mohammad R. Aligoodarz ◽  
Mohammad Reza Soleimani Tehrani ◽  
Hadi Karrabi ◽  
Mohammad R. Roshani
Keyword(s):  
Numerical Modeling ◽  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Mechanical Damage ◽  
3D Numerical Modeling ◽  
Compressor Blades ◽  
Turbine Performance ◽  
Common Causes ◽  
Sst Turbulence Model ◽  
Compressor Performance

Turbo machineries including compressors performance degrades over the period of operation and deviates from design levels due to causes including dust entrance into the compressor, blades mechanical damage, erosion and corrosion. These lead to reduction in compressor performance, efficiency and pressure ratio. Subsequently gas turbine performance is affected since their operation sate is correlated. In this study the numerical investigation of common causes that determine geometric characteristics of a 2-stage centrifugal compressor running in a gas station, including blades fouling and corrosion is performed. 3D Numerical modeling is implemented along with utilization of Shear Stress Transport (SST) turbulence model and independency from the grids is verified.

Improving a one-dimensional centrifugal compressor performance prediction method

2005 ◽  
Vol 219 (8) ◽  
pp. 653-659 ◽  
Author(s):  
E Swain
Keyword(s):  
Centrifugal Compressor ◽  
Performance Prediction ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Prediction Method ◽  
Compressor Cascade ◽  
One Dimensional ◽  
Compressor Performance ◽  
Cfd Analyses

A one-dimensional centrifugal compressor performance prediction technique that has been available for some time is updated as a result of extracting the component performance from three-dimensional computational fluid dynamic (CFD) analyses. Confidence in the CFD results is provided by comparison of overall performance for one of the compressor examples. The extracted impeller characteristic is compared with the original impeller loss model, and this indicated that some improvement was desirable. The position of least impeller loss was determined using a traditional axial compressor cascade method, and suitable algebraic expressions were derived to match the CFD data. The merit of the approach lies with the relative ease that CFD component performance currently can be achieved and adjusting one-dimensional methods to agree with the CFD-derived models.

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