scholarly journals Analysis and Improvement of a Two-Stage Centrifugal Compressor Used in an MW-Level Gas Turbine

2018 ◽  
Vol 8 (8) ◽  
pp. 1347 ◽  
Author(s):  
Wei Zhu ◽  
Xiao-Dong Ren ◽  
Xue-Song Li ◽  
Chun-Wei Gu
Keyword(s):  
High Pressure ◽  
Gas Turbine ◽  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Low Pressure ◽  
Two Stage ◽  
Vaned Diffuser ◽  
Pressure Stage ◽  
Optimization System ◽  
High Pressure Stage

The performance of a low/high-pressure-stage centrifugal compressor in a land-use MW-level gas turbine with a pressure ratio of approximately 11 is analyzed and optimized with a 1D aerodynamic design and modeling optimization system. 1D optimization results indicate that the diameter ratio of the low-pressure-stage centrifugal compressor with a vane-less diffuser, and the divergent angle of the high-pressure-stage centrifugal compressor with a vaned diffuser, are extremely large and result in low efficiency. Through modeling design and optimization system analysis, a tandem vaned diffuser is used in the low-pressure stage, and a tandem vaned diffuser with splitter vanes is adopted in the high-pressure stage. Computational fluid dynamics (CFD) results show that the pressure ratio and efficiency of the optimized low/high-pressure-stage centrifugal compressor are significantly improved. Coupling calculations of the low/high-pressure stage of the original and optimized designs are conducted based on the results of MW-level gas turbine cycles. CFD results show that the pressure ratio and efficiency of the optimized two-stage centrifugal compressor increase by approximately 8% and 4%, respectively, under three typical load conditions of 100%, 90%, and 60%.

Aerodynamic Investigation on a 3D-Vaned Diffuser Applied on a High Flow 3D Impeller

2012 ◽  
Author(s):  
H. Strohmeyer ◽  
A. Hildebrandt
Keyword(s):  
High Pressure ◽  
Centrifugal Compressor ◽  
High Flow ◽  
Compressor Stage ◽  
Vaned Diffuser ◽  
High Incidence ◽  
High Pressure Stage ◽  
Stage Efficiency ◽  
Ratio Reduction ◽  
Aerodynamic Investigation

This paper discusses the effect of a diffuser ratio reduction from r4/r2 = 1.55 to r4/r2 = 1.35 of a centrifugal compressor stage and an approach to retain the efficiency by applying a vaned diffuser. Initially, the diffuser ratio of a high flow, high pressure stage is decreased. Following, the stage having the smallest diffuser ratio is used to investigate the performance of a vaned diffuser, whose trailing edge is shifted into the U-turn. The discussion shows a possible improvement by the diffuser vane enlargement. The total stage efficiency of the diffuser ratio of r4/r2 = 1.55 can be retained as long as the separation due to high incidence of the vaned diffuser is low.

Numerical Investigation of Low Solidity Vaned Diffuser Performance in a High-Pressure Centrifugal Compressor: Part I — Influence of Vane Solidity

2007 ◽  
Author(s):  
JongSik Oh ◽  
Giri L. Agrawal
Keyword(s):  
High Pressure ◽  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Limited Range ◽  
Design Flow ◽  
Design Parameters ◽  
Moderate Pressure ◽  
Vaned Diffuser ◽  
High Pressure Ratio ◽  
Wide Operating

The LSD (Low Solidity Diffuser) is becoming popular in most industrial centrifugal compressor designs because it is found to offer a wide operating flow range while maintaining a similar level of efficiency as in case of conventional vaned diffusers. Most related studies have been for low or moderate pressure ratio machines providing a limited range of design information for high-pressure ratio compressors. As a first step forward information of design parameters, a numerical CFD investigation was applied to a high-pressure industrial centrifugal compressor of design total-to-static pressure ratio of 4.0 with LSDs of NACA65-series profiles whose solidity varies from 0.452 to 0.968 in 5 cases with all the other design parameters fixed. Near design flow, the case of 0.839 solidity has the highest isentropic total-to-static efficiency. Other performance changes are accordingly investigated.

scholarly journals Study the Effect of Temperature on Methane Desorption Based on Thermodynamics and Kinetics

2020 ◽  
Author(s):  
Zheng Gao ◽  
Dongmin Ma ◽  
Yue Chen ◽  
Chao Zheng ◽  
Jinxiang Teng
Keyword(s):  
High Pressure ◽  
Adsorption Capacity ◽  
Free Path ◽  
Low Pressure ◽  
Coking Coal ◽  
Desorption Process ◽  
Pressure Stage ◽  
High Pressure Stage ◽  
Desorption Hysteresis ◽  
Methane Desorption

Abstract Desorption hysteresis is important for primary gas production. Temperature may cause serious change in the methane adsorption/desorption behaviors. In order to study the mechanism of methane desorption and desorption hysteresis, three sets of samples of long flame coal, coking coal, and anthracite were collected, and experiments such as microscopic composition determination, liquid nitrogen adsorption, and isothermal adsorption/desorption were performed. From the perspectives of desorption kinetics, desorption thermodynamics and methane occurrence state, the differences in methane and methane desorption characteristics and the desorption hysteresis mechanism are discussed. The results show that at the same temperature, anthracite (SH3#) has the largest saturated adsorption capacity and residual adsorption capacity, followed by coking coal (SGZ11#), and long -flame coal (DFS4#) is the smallest. As the temperature rises, the theoretical desorption rate and residual adsorption capacity of anthracite (SH3#) and coking coal (SGZ11#) will increase first and then decrease. Temperature and methane desorption are not completely positive effects, and temperature may have a threshold for promoting methane desorption. It is necessary to comprehensively consider the influence of temperature on the activation of gas molecules and the pore structure of coal. Under the premise of a certain temperature, as the pressure increases, the desorption hysteresis rate changes in a logarithmic downward trend, and the methane desorption hysteresis rate in the low pressure stage (P 4MPa) is large, and the methane desorption hysteresis rate in the high-pressure stage (P>4MPa) is lower; During the isobaric adsorption process, the adsorption capacity of anthracite (SH3#) increases the fastest, followed by SGZ11#, and DFS4# is the smallest. In the low-pressure stage (P 4MPa), the adsorption capacity increases significantly with the increase of pressure, but in the high pressure stage (P 4MPa), the adsorption capacity does not change significantly with pressure, but gradually stabilizes. Under the same pressure, the molecular free path of methane increases with temperature. Under the premise of constant temperature, in the low-pressure stage (0<P<4MPa), when the pressure continues to decrease, the free path of methane molecules increases significantly, resulting in a decrease in the diffusion capacity. In the high-pressure stage (4<P<8MPa), when the pressure continues to decrease, the free path of methane molecules does not change significantly; DFS4#, SGZ11#, SH3# sample desorption process of three sets of samples, the intermediate adsorption heat is greater than the isometric adsorption heat during the adsorption process, indicating that the desorption process needs to continuously absorb heat from outside the system. The energy difference produced in the process of adsorption and desorption causes the desorption hysteresis effect. The greater the difference in the isometric heat value of adsorption, the more significant the hysteresis.

Aerodynamics and Aeroelasticity of Impeller Vane Interactions in a High Pressure Ratio Centrifugal Compressor

2010 ◽  
Author(s):  
S. K. Krishnababu ◽  
M. Imregun ◽  
J. S. Green ◽  
D. Hoyniak
Keyword(s):  
High Pressure ◽  
Centrifugal Compressor ◽  
Computational Study ◽  
Pressure Ratio ◽  
Leading Edge ◽  
Computational Domain ◽  
Trailing Edge ◽  
Vaned Diffuser ◽  
High Pressure Ratio ◽  
Radial Gap

The interaction between impeller and diffuser in a high-pressure ratio centrifugal compressor is considered to have a strong influence on the unsteady flow field, the impeller response and the performance of the compressor. A computational study was performed to investigate the interactions between a backswept impeller and its downstream vaned diffuser with emphasis on the impeller response at 2 different vane settings. The unsteady computations were conducted using two different modelling levels of increasing fidelity. The computational domain included an impeller with 15 main and 15 splitter blades and 22-vane wedge diffuser. A steady-state stage calculation with a mixing-plane interface between the impeller trailing edge and the vane leading edge was conducted first to assess the performance. A whole-annulus unsteady stage calculation was conducted to study the response of the impeller. The effect of radial gap between the impeller trailing edge and the vane leading edge on the performance of the impeller was investigated in some detail. In agreement with other similar studies, the results suggest that there is an optimum value of the radius ratio for best performance.

Rotor Casing Contouring in High Pressure Stages of Heavy Duty Gas Turbine Compressors With Large Tip Clearance Heights

2009 ◽  
Author(s):  
Georg Kro¨ger ◽  
Christian Cornelius ◽  
Eberhard Nicke
Keyword(s):  
High Pressure ◽  
Gas Turbine ◽  
Performance Improvement ◽  
Axial Compressor ◽  
Tip Clearance ◽  
Pressure Stage ◽  
Design Point ◽  
Pressure Loss Coefficient ◽  
Exit Pressure ◽  
High Pressure Stage

Clearance leakage losses of axial compressor rotors and stators have a major impact on the overall compressor performance. The clearance heights in the last stages (high pressure stages) of a gas turbine compressor are very large in comparison to the low pressure stages due to mechanical constraints and small blade heights. The reduction of clearance leakage losses in a high pressure stage still holds an important potential for the overall performance improvement at design point conditions. In the following work, a method for tip clearance loss reduction by circumferential casing contouring above a high pressure stage rotor with a constant clearance height is presented. The subsonic compressor blade provides Siemens HPA-Family [1, 2, 3] airfoils. Starting over with a 3D-Optimization of the mentioned rotor casing the work additionally refers to the aerodynamic effects and the off design performance of the optimized geometry. It has been found that an optimized casing and blade tip contour lead to a smaller overall clearance mass flow and lower pressure loss coefficient of the clearance flow so that the endwall blockage is reduced and the stage performance is improved by about 0.35% at design point conditions. Furthermore it was found that the performance improvement drops with increasing exit pressure to about 0.1% close to stall conditions. At lower exit pressure values the optimized geometry provides an additional performance improvement in comparison to the baseline configuration.

scholarly journals Impact of Inlet Filter Pressure Loss on Single and Two-Spool Gas Turbine Engines for Different Control Modes

2014 ◽  
Vol 136 (9) ◽  
Author(s):  
Uyioghosa Igie ◽  
Orlando Minervino
Keyword(s):  
High Pressure ◽  
Gas Turbine ◽  
Rotational Speed ◽  
Gas Turbines ◽  
Pressure Loss ◽  
Pressure Ratio ◽  
Two Stage ◽  
Pressure Losses ◽  
Stage System ◽  
Pressure Compressor

Inlet filtration systems are designed to protect industrial gas turbines from air borne particles and foreign objects, thereby improving the quality of air for combustion and reducing component fouling. Filtration systems are of varying grades and capture efficiencies, with the higher efficiency systems filters providing better protection but higher pressure losses. For the first time, two gas turbine engine models of different configurations and capacities have been investigated for two modes of operation (constant turbine entry temperature (TET) and load/power) for a two- and three-stage filter system. The main purpose of this is to present an account on factors that could decide the selection of filtration systems by gas turbine operators, solely based on performance. The result demonstrates that the two-spool engine is only slightly more sensitive to intake pressure loss relative to the single-spool. This is attributed to higher pressure ratio of the two-spool as well as the deceleration of the high pressure compressor (HPC)/high pressure turbine (HPT) shaft rotational speed in a constant TET operation. The compressor of the single-spool engine and the low pressure compressor (LPC) of the two-spool shows similar behavior: slight increase in pressure ratio and reduced surge margin at their constant rotational speed operation. Loss in shaft power is observed for both engines, about 2.5% at 1000 Pa loss. For constant power operation there is an increase in fuel flow and TET, and as a result the creep life was estimated. The result obtained indicates earlier operating hours to failure for the three-stage system over the two-stage by only a few thousand hours. However, this excludes any degradation due to fouling that is expected to be more significant in the two-stage system.

Numerical Investigation of Low Solidity Vaned Diffuser Performance in a High-Pressure Centrifugal Compressor: Part II—Influence of Vane Stagger

2008 ◽  
Author(s):  
JongSik Oh ◽  
Charles W. Buckley ◽  
Giri L. Agrawal
Keyword(s):  
High Pressure ◽  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Pressure Rise ◽  
Poor Performance ◽  
Design Flow ◽  
Design Parameters ◽  
Vaned Diffuser ◽  
High Pressure Ratio ◽  
Compressor Performance

As the second part, following the authors’ previous study, the influence of the LSD (Low Solidity Diffuser) vane stagger on high-pressure ratio centrifugal compressor performance is numerically investigated with all the other design parameters fixed, while vane solidities are in the range from 0.70 to 0.85. Vane stagger is varied for 6 cases from 8.55 deg to 22.37 deg with the NACA65-(4A10)06 airfoil profile, and the Stage interface scheme is applied for an interaction treatment. As the vane stagger increases, changing from 10.55 deg to 19.58 deg, the compressor overall performance is generally improved, but two extreme cases of vane stagger of 8.55 deg and 22.37 deg provide poor performance. Vane stagger of 19.58 deg shows the highest efficiency and pressure rise near design flow, while vane stagger of 13.76 deg has the largest operating range with acceptable performance of efficiency and pressure ratio.

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