Influence of Impeller Fairing Cone Geometry on Cavitating Flow Behavior in a Cryogenic Liquid Turbine Expander

2016 ◽  
Author(s):  
Ke Wang ◽  
Jinju Sun ◽  
Peng Song ◽  
Changjiang Huo
Keyword(s):  
Large Scale ◽  
Bubble Dynamics ◽  
Flow Behavior ◽  
Hydraulic Turbine ◽  
Sensitivity Study ◽  
Cryogenic Liquid ◽  
Cavitating Flow ◽  
Air Separation ◽  
Separation Unit ◽  
Thermodynamic Effect

A single stage cryogenic liquid turbine expander is developed as a replacement for traditional Joule-Thomson valves used in the large-scale internal compression air-separation unit for the purpose of energy saving. Similar to the conventional hydraulic turbine, detrimental swirling and cavitation flow is also encountered at turbine expander impeller exit and its successive diffuser tube, but due to significant thermodynamic effect of cryogenic fluid flow, it is much more complicated than the conventional hydraulic turbine. In the present study, cavitating flow mechanism of the turbine expander is investigated first with a combination of the homogenous multiphase mixture model and the Rayleigh-Plesset model, where the former treats liquid and gas as a continuum mixture and the latter depicts the bubble dynamics. Then sensitivity study is conducted for the impeller fairing cone geometry on suppression of cavitating flow. The following are demonstrated: with a use of the fairing cone, flow behavior near and downstream the impeller exit is significantly improved, where the low static pressure region is reduced and the local temperature rise decreases, subsequently the cavitating flow is effectively suppressed. The cavitating flow is sensitive to a tuning of the fairing cone geometry, and an optimal design of the cone geometry is essential.

Numerical Investigation of a Cryogenic Liquid Turbine Performance and Flow Behavior

2008 ◽  
Author(s):  
Wei Zhao ◽  
Jinju Sun ◽  
Hezhao Zhu ◽  
Cheng Li ◽  
Guocheng Cai ◽  
...  
Keyword(s):  
Numerical Investigation ◽  
Large Scale ◽  
Flow Behavior ◽  
Cryogenic Liquid ◽  
Air Separation ◽  
Design Flow ◽  
Suction Surface ◽  
Navier Stokes Equation ◽  
Separation Unit ◽  
Turbine Performance

A single stage cryogenic liquid turbine is designed for a large-scale internal compression air-separation unit to replace the Joule-Thompson valve and recover energy from the liquefied air during throttling process. It includes a radial vaned nozzle, and 3-dimensional impeller. Numerical investigation using 3-D incompressible Navier-Stokes Equation together with Spalart-Allmaras turbulence model and mixing plane approach at the impeller and stator interface are carried out at design and off-design flow. At design condition, recovered shaft power has amounted to 185.87 kW, and pressure in each component decreases smoothly and reaches to the expected scale at outlet. At small flow rates, flow separation is observed near the middle section of blade suction surface, which may cause local vaporization and even cavitation. To further improve the turbine flow behavior and performance, geometry parametric study is carried out. Influence of radial gap between impeller and nozzle blade rows, and nozzle stagger angle on turbine performance are investigated and clarified. Results arising from the present study provide some guidance for cryogenic liquid turbine optimal design.

Numerical Study of Cavitating Behavior in a Cryogenic Liquid Turbine

2012 ◽  
Author(s):  
Zhilong He ◽  
Yunzheng Ge ◽  
Jinju Sun ◽  
Ke Wang
Keyword(s):  
Numerical Study ◽  
Flow Behavior ◽  
Cone Angle ◽  
Cryogenic Liquid ◽  
Gas Production ◽  
Influential Factors ◽  
Air Separation ◽  
Separation Unit ◽  
Air Separation Unit ◽  
Cavitation Behavior

The cryogenic liquid turbine is used in the internal compression air-separation unit to replace the Joule-Thomson valve for the purpose of energy-saving. Evaporation of the liquefied air must be reduced to a minimum to increase gas production of the air-separation unit and simultaneously prevent cavitation damage to the turbine structure during throttling process. In the present study, cavitation behavior in the liquid turbine is investigated and some influential factors are identified. A numerical flow model is established in a turbine stage environment, which includes an asymmetrical volute, variable geometry nozzle, impeller, and diffuser. The simulation is conducted by using the ANSYS-CFX, where an iterative model is incorporated to update the liquefied gas properties at local temperature, and the Rayleigh-Plesset model is used for describing cavitation behavior. The cavitation model is validated first by experimental data of a hydrofoil in liquid nitrogen and its suitability for cryogenic fluid flow has been justified. Both steady and unsteady simulations are conducted respectively and the results are compared. At the design condition, the vapor fraction in the impeller produced by the unsteady simulation is similar to that obtained by the steady simulation. At off-design condition, the turbine flow behavior is far from the steady assumption. The influence of the diffuser duct cone angle on cavitation behavior is also investigated, which demonstrate that geometry modification of diffuser duct is effective to suppress the cavitation flow.

Investigation of Impeller Strength for a Cryogenic Liquid Turbine

2010 ◽  
Author(s):  
Yan Ren ◽  
Jinju Sun ◽  
Rongye Zheng ◽  
Peng Song ◽  
Ke Wang
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
Centrifugal Force ◽  
Low Temperatures ◽  
Large Scale ◽  
Cryogenic Liquid ◽  
Air Separation ◽  
Design Flow ◽  
Navier Stokes Equation ◽  
Separation Unit

A single stage cryogenic liquid turbine is designed for a large-scale internal compression air-separation unit to replace the Joule-Thompson valve and recover energy from the liquefied air during throttling process. It includes a 3-dimensional impeller, variable geometry nozzle, and asymmetrical volute. Strength evaluation of such a liquid turbine is both essential and complicated, which involves a proper evaluation of stress acting on the components and mechanical property of the chosen materials at low temperature. For metals under low temperatures, brittle fracture of the metal may occur prior to fatigue damage. A comprehensive consideration of low-temperature mechanical properties of materials and mechanical loads (due to hydrodynamic force and centrifugal force) acting on the components is of particular importance. Aluminum alloy 2031 is used for the turbine impeller and its mechanical properties under low temperatures are analyzed. To evaluate the stress acting on the components, numerical investigation using 3-D incompressible Navier-Stokes Equation together with k-epsilon turbulence model and mixing plane approach at rotator-stator interface are carried out at design and off-design flow with different nozzle-vane settings. The obtained pressure force is transformed into hydrodynamic load acting on the solid surface by means of fluid-solid interaction technology, and then used in the FEM (Finite Element Method) structure analysis together with the centrifugal force. Stress distribution of the component is obtained and deformation of the component analyzed. Evaluation of impeller strength is conducted for the cryogenic liquid turbine by combining the foregoing two aspects, and a use of alloy 2031 for the turbine expander is validated.

scholarly journals Power-to-Green Methanol via CO2 Hydrogenation—A Concept Study Including Oxyfuel Fluidized Bed Combustion of Biomass

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4638
Author(s):  
Simon Pratschner ◽  
Pavel Skopec ◽  
Jan Hrdlicka ◽  
Franz Winter
Keyword(s):  
Large Scale ◽  
Positive Impact ◽  
Renewable Energy Sources ◽  
Air Separation ◽  
Model Parameters ◽  
Processing Unit ◽  
Fluidized Bed Combustion ◽  
Separation Unit ◽  
Oxyfuel Combustion ◽  
Wind Park

A revolution of the global energy industry is without an alternative to solving the climate crisis. However, renewable energy sources typically show significant seasonal and daily fluctuations. This paper provides a system concept model of a decentralized power-to-green methanol plant consisting of a biomass heating plant with a thermal input of 20 MWth. (oxyfuel or air mode), a CO2 processing unit (DeOxo reactor or MEA absorption), an alkaline electrolyzer, a methanol synthesis unit, an air separation unit and a wind park. Applying oxyfuel combustion has the potential to directly utilize O2 generated by the electrolyzer, which was analyzed by varying critical model parameters. A major objective was to determine whether applying oxyfuel combustion has a positive impact on the plant’s power-to-liquid (PtL) efficiency rate. For cases utilizing more than 70% of CO2 generated by the combustion, the oxyfuel’s O2 demand is fully covered by the electrolyzer, making oxyfuel a viable option for large scale applications. Conventional air combustion is recommended for small wind parks and scenarios using surplus electricity. Maximum PtL efficiencies of ηPtL,Oxy = 51.91% and ηPtL,Air = 54.21% can be realized. Additionally, a case study for one year of operation has been conducted yielding an annual output of about 17,000 t/a methanol and 100 GWhth./a thermal energy for an input of 50,500 t/a woodchips and a wind park size of 36 MWp.

scholarly journals Clean Hydrogen and Ammonia Synthesis in Paraguay from the Itaipu 14 GW Hydroelectric Plant

2019 ◽  
Vol 3 (4) ◽  
pp. 87
Author(s):  
Massimo Rivarolo ◽  
Gustavo Riveros-Godoy ◽  
Loredana Magistri ◽  
Aristide F. Massardo
Keyword(s):  
Large Scale ◽  
Ammonia Synthesis ◽  
Hydroelectric Plant ◽  
Electrical Energy ◽  
Economic Feasibility ◽  
Air Separation ◽  
Production Costs ◽  
Methane Steam Reforming ◽  
Hydroelectric Power ◽  
Separation Unit

This paper aims at investigating clean hydrogen production from the large size (14 GW) hydroelectric power plant of Itaipu, located on the border between Paraguay and Brazil, the two countries that own and manage the plant. The hydrogen, produced by a water electrolysis process, is converted into ammonia through the well-known Haber-Bosch process. Hydraulic energy is employed to produce H2 and N2, respectively, from a large-scale electrolysis system and an air separation unit. An economic feasibility analysis is performed considering the low electrical energy price in this specific scenario and that Paraguay has strong excess of renewable electrical energy but presents a low penetration of electricity. The proposal is an alternative to increase the use of electricity in the country. Different plant sizes were investigated and, for each of them, ammonia production costs were determined and considered as a term of comparison with traditional ammonia synthesis plants, where H2 is produced from methane steam reforming and then purified. The study was performed employing a software developed by the authors’ research group at the University of Genoa. Finally, an energetic, environmental, and economic comparison with the standard production method from methane is presented.

Flow Simulation and Diagnosis Through Hydraulic Turbines Using a RNG k-ω Turbulence Model

2010 ◽  
Author(s):  
Shuhong Liu ◽  
Xiaojing Wu ◽  
Yulin Wu
Keyword(s):  
Turbulence Model ◽  
Large Scale ◽  
Flow Behavior ◽  
Flow Simulation ◽  
Hydraulic Turbine ◽  
Francis Turbine ◽  
Design Stage ◽  
Hydro Power ◽  
Large Power ◽  
Power Stations

Francis turbine is widely employed in large scale hydro-power stations in the world with main characteristics of efficiency, stability and cavitation. In practical establishment, each large power station must develop a new Francis turbine for its special natural condition and requirement, such as higher efficiency for utilization of natural resources. CFD has been developed greatly and helped a lot in hydraulic design stage of the turbine. In this paper, firstly, a new RNG k–ω turbulence model is proposed based on the RNG k–ε model, which brings the nonlinear term of the mean fluid flow transition to the ω equation in the original k–ω model. And, this RNG k–ω model has been used to predict the energy performances for Francis turbine. Then, the flow diagnosis method in the turbine runner based on vorticity parameters is presented, following the detailed flow behavior revealed. Finally, the simulation results for different model Francis turbines have been compared and analyzed for optimizing the energy performances of the turbine. The model test results indicate that the efficiency of hydraulic turbine has been improved from 93.6% to 94.5%.

Development of Parts Family Manage System Based on PDM in Large-Scale Air Separation Equipment

2012 ◽  
Vol 605-607 ◽  
pp. 288-291
Author(s):  
Rui Zhu ◽  
Guang Meng ◽  
Hong Guang Li
Keyword(s):  
Large Scale ◽  
Design Procedure ◽  
Air Separation ◽  
Practical Significance ◽  
Design Environment ◽  
Separation Unit ◽  
Software Interface ◽  
Database Structure ◽  
Air Separation Unit ◽  
Separation Equipment

Large-scale air separation equipment is used widely in chemical industry. It can provide oxygen, nitrogen and argon for the production process. Based on the deep analysis of the working principle and using equipment, the air separation unit product data management (PDM) system is developed by Visual Basic (VB) in this paper develops. The modularized design procedure and grouping technique (GT) are adopted in this system. The morphological matrix is used to establish their coordination relationship among parts. The system has many characters, such as perfect function, reasonable database structure, and concise software interface layout. Optimizing equipment parts management properly and effectively has important practical significance in designing the subsequent product development work and establishing concurrent design environment of the air separation unit.

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