scholarly journals A Comprehensive Three-Dimensional Analysis of a Large-Scale Multi-Fuel CFB Boiler Burning Coal and Syngas. Part 1. The CFD Model of a Large-Scale Multi-Fuel CFB Combustion

Entropy ◽  
2020 ◽  
Vol 22 (9) ◽  
pp. 964 ◽  
Author(s):  
Jaroslaw Krzywanski ◽  
Karol Sztekler ◽  
Mateusz Szubel ◽  
Tomasz Siwek ◽  
Wojciech Nowak ◽  
...  
Keyword(s):  
Large Scale ◽  
Circulating Fluidized Bed ◽  
Three Dimensional ◽  
Cfd Model ◽  
Cfb Boiler ◽  
Coal Sludge ◽  
Syngas Combustion ◽  
Computational Fluid Dynamics Cfd ◽  
Burning Coal ◽  
Complex Phenomena

The paper is focused on the idea of multi-fuel combustion in a large-scale circulating fluidized bed (CFB) boiler. The article discusses the concept of simultaneous coal and syngas combustion. A comprehensive three-dimensional computational fluid dynamics (CFD) model is developed, which allows us to describe complex phenomena that occur in the combustion chamber of the CFB boiler burning coal and syngas produced from coal sludge.

scholarly journals A Comprehensive, Three-Dimensional Analysis of a Large-Scale, Multi-Fuel, CFB Boiler Burning Coal and Syngas. Part 2. Numerical Simulations of Coal and Syngas Co-Combustion

Entropy ◽  
2020 ◽  
Vol 22 (8) ◽  
pp. 856 ◽  
Author(s):  
Jaroslaw Krzywanski ◽  
Karol Sztekler ◽  
Mateusz Szubel ◽  
Tomasz Siwek ◽  
Wojciech Nowak ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Large Scale ◽  
Bituminous Coal ◽  
Circulating Fluidized Bed ◽  
Three Dimensional ◽  
Cfb Boiler ◽  
Start Up ◽  
Carbon Dioxide Concentrations ◽  
Secondary Air ◽  
Burning Coal

This paper presents the results of numerical computations for a large-scale OFz-425 CFB (circulating fluidized bed) boiler utilizing coal and syngas. Four different operating scenarios are considered, including the reference variant, corresponding to the conventional, mono-combustion of bituminous coal, and three tests involving replacement of secondary air and part of the coal stream with syngas fed by start-up burners. Pressure, gas velocity, temperature, and carbon dioxide distribution in the combustion chamber are discussed in the paper. The results indicate that the syngas supply leads to an increase in local temperature and carbon dioxide concentrations. The proposed concept is not advisable as it may lead to frequent emergency stops of the CFB boiler.

scholarly journals A Multidimensional and Multiscale Model for Pressure Analysis in a Reservoir-Pipe-Valve System

2018 ◽  
Author(s):  
Feng Jie Zheng ◽  
Fu Zheng Qu ◽  
Xue Guan Song
Keyword(s):  
Pressure Fluctuation ◽  
Large Scale ◽  
Three Dimensional ◽  
Industrial Process ◽  
Multiscale Model ◽  
Computational Time ◽  
Small Scale ◽  
Cfd Model ◽  
Computationally Efficient ◽  
Proposed Model

Reservoir-pipe-valve (RPV) systems are widely used in many industrial process. The pressure in an RPV system plays an important role in the safe operation of the system, especially during the sudden operation such as rapid valve opening/closing. To investigate the pressure especially the pressure fluctuation in an RPV system, a multidimensional and multiscale model combining the method of characteristics (MOC) and computational fluid dynamics (CFD) method is proposed. In the model, the reservoir is modeled by a zero-dimensional virtual point, the pipe is modeled by a one-dimensional MOC, and the valve is modeled by a three-dimensional CFD model. An interface model is used to connect the multidimensional and multiscale model. Based on the model, a transient simulation of the turbulent flow in an RPV system is conducted, in which not only the pressure fluctuation in the pipe but also the detailed pressure distribution in the valve are obtained. The results show that the proposed model is in good agreement with the full CFD model in both large-scale and small-scale spaces. Moreover, the proposed model is more computationally efficient than the CFD model, which provides a feasibility in the analysis of complex RPV system within an affordable computational time.

scholarly journals A Multidimensional and Multiscale Model for Pressure Analysis in a Reservoir-Pipe-Valve System

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
Feng Jie Zheng ◽  
Chao Yong Zong ◽  
William Dempster ◽  
Fu Zheng Qu ◽  
Xue Guan Song
Keyword(s):  
Large Scale ◽  
Pressure Fluctuations ◽  
Three Dimensional ◽  
Multiscale Model ◽  
Computational Time ◽  
Small Scale ◽  
Dimensional System ◽  
Cfd Model ◽  
Computationally Efficient ◽  
Proposed Model

Reservoir-pipe-valve (RPV) systems are widely used in many industrial processes. The pressure in an RPV system plays an important role in the safe operation of the system, especially during the sudden operations such as rapid valve opening or closing. To investigate the pressure response, with particular interest in the pressure fluctuations in an RPV system, a multidimensional and multiscale model combining the method of characteristics (MOC) and computational fluid dynamics (CFD) method is proposed. In the model, the reservoir is modeled as a zero-dimensional virtual point, the pipe is modeled as a one-dimensional system using the MOC, and the valve is modeled using a three-dimensional CFD model. An interface model is used to connect the multidimensional and multiscale model. Based on the model, a transient simulation of the turbulent flow in an RPV system is conducted in which not only the pressure fluctuation in the pipe but also the detailed pressure distribution in the valve is obtained. The results show that the proposed model is in good agreement when compared with a high fidelity CFD model used to represent both large-scale and small-scale spaces. As expected, the proposed model is significantly more computationally efficient than the CFD model. This demonstrates the feasibility of analyzing complex RPV systems within an affordable computational time.

CFD Analysis of the Primary Side in a Helical-Coil Once-Through Steam Generator

2017 ◽  
Author(s):  
Kai Ye ◽  
Yaoli Zhang ◽  
Jianshu Lin ◽  
Ning Li ◽  
Yinglin Yang ◽  
...  
Keyword(s):  
Steam Generator ◽  
Nuclear Power ◽  
Rational Design ◽  
Large Scale ◽  
Three Dimensional ◽  
Helical Coil ◽  
Complicated Structure ◽  
Ansys Fluent ◽  
Flow Parameters ◽  
Computational Fluid Dynamics Cfd

The helical-coil once-through steam generator (OTSG) is usually used in the nuclear power plant when the compactness of equipment was taken into consideration. The investigation of flow parameters in the primary side is valuable for the optimization of the OTSG. The purpose of this research is to obtain a further understanding of fluid behaviors in the primary side of the OTSG to achieve a more rational design. Using ANSYS ICEM and ANSYS FLUENT, a three-dimensional (3D) computational fluid dynamics (CFD) model was created and analyzed. Through a series of cases, the velocity profiles and pressure drop through the primary side of the helical-coil OTSG have been calculated, and the influences of different structure designs on the coolant flow parameters have also been tested. Ultimately some pertinent suggestions for improvements were proposed, and insight is obtained into the importance of various modeling considerations in such a model with a complicated structure and large-scale grids.

Development and Validation of a 3-Dimensional Computational Fluid Dynamics (CFD) Model for Rectangular Settling Tanks in New York City Water Pollution Control Plants

2009 ◽  
Vol 4 (1) ◽  
Author(s):  
K. Ramalingam ◽  
J. Fillos ◽  
S. Xanthos ◽  
M. Gong ◽  
A. Deur ◽  
...  
Keyword(s):  
Water Pollution ◽  
Fluid Dynamics ◽  
New York ◽  
Computational Fluid Dynamics ◽  
New York City ◽  
Pollution Control ◽  
York City ◽  
Three Dimensional ◽  
Cfd Model ◽  
Computational Fluid Dynamics Cfd

New York City provides secondary treatment to approximately 78.6 m3/s among its 14 water pollution control plants (WPCPs). The process of choice has been step-feed activated sludge. Changes to the permit limits require nitrogen removal in WPCPs discharging into the Long Island Sound. The City has selected step feed biological nitrogen removal (BNR) process to upgrade the affected plants. Step feed BNR requires increasing the concentration of mixed liquors, (MLSS), which stresses the Gould II type rectangular final settling tanks (FSTs). To assess performance and evaluate alternatives to improve efficiency of the FSTs at the higher loads, New York City Department of Environmental Protection (NYCDEP) and City College of New York (CCNY) have developed a three-dimensional computer model depicting the actual structural configuration of the tanks and the current and proposed hydraulic and solids loading rates. Using Computational Fluid Dynamics (CFD) Model, Fluent 6.3.26TM as the base platform, sub-models of the SS settling characteristics as well as turbulence, flocculation, etc. were incorporated. This was supplemented by field and bench scale experiments to quantify the co-efficients integral to the sub-models. As a result, a three-dimensional model has been developed that is being used to consider different baffle arrangements, sludge withdrawal mechanisms and loading alternatives to the FSTs.

Three-Dimensional CFD Analysis of a Spring-Loaded Pressure Safety Valve From Opening to Re-Closure

2010 ◽  
Author(s):  
Xue Guan Song ◽  
Lei Cui ◽  
Young Chul Park
Keyword(s):  
Safety Valve ◽  
Three Dimensional ◽  
Cfd Model ◽  
Flow Features ◽  
Valve Opening ◽  
Computational Fluid Dynamics Cfd ◽  
Multiple Domains ◽  
Future Work ◽  
Mesh Technique ◽  
Detailed Picture

We describe the dynamic analysis of a spring-loaded pressure safety valve (PSV) using a moving mesh technique and transient analysis in computational fluid dynamics (CFD). Multiple domains containing pure structural meshes are generated to ensure that the correlative mesh could change properly without negative volumes. With a geometrically accurate CFD model including the PSV and vessel rather than only the PSV, the entire process from valve opening to valve re-closure is presented. A detailed picture of the compressible fluid flowing through the PSV is obtained, including flow features in the very small seat region. In addition, the forces on the disc and its motion are monitored. Results from the model were very useful in investigating the dynamic and fluid characteristics of the PSV. Our practical CFD model has the potential to reduce the costs and risks associated with the development of new pressure safety valve designs. Future work will focus on improving the spring stiffness and seat region to eliminate or reduce vibration during the re-closure process.

Prediction of Raceways in a Blast Furnace

2006 ◽  
Author(s):  
Naresh K. Selvarasu ◽  
D. Huang ◽  
Zumao Chen ◽  
Mingyan Gu ◽  
Yongfu Zhao ◽  
...  
Keyword(s):  
Particle Size ◽  
Blast Furnace ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Gas Oil ◽  
Cfd Model ◽  
Coke Particle ◽  
Fuel Gas ◽  
Computational Fluid Dynamics Cfd ◽  
Insight Into

In a blast furnace, preheated air and fuel (gas, oil or pulverized coal) are often injected into the lower part of the furnace through tuyeres, forming a raceway in which the injected fuel and some of the coke descending from the top of the furnace are combusted and gasified. The shape and size of the raceway greatly affect the combustion of, the coke and the injected fuel in the blast furnace. In this paper, a three-dimensional (3-D) computational fluid dynamics (CFD) model is developed to investigate the raceway evolution. The furnace geometry and operating conditions are based on the Mittal Steel IH7 blast furnace. The effects of Tuyere-velocity, coke particle size and burden properties are computed. It is found that the raceway depth increases with an increase in the tuyere velocity and a decrease in the coke particle size in the active coke zone. The CFD results are validated using experimental correlations and actual observations. The computational results provide useful insight into the raceway formation and the factors that influence its size and shape.

Transient Analysis of a Spring-Loaded Pressure Safety Valve Using Computational Fluid Dynamics (CFD)

2010 ◽  
Vol 132 (5) ◽  
Author(s):  
Xue Guan Song ◽  
Lin Wang ◽  
Young Chul Park
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Safety Valve ◽  
Three Dimensional ◽  
Pressure Vessels ◽  
Moving Mesh ◽  
Cfd Model ◽  
Ansys Cfx ◽  
Computational Fluid Dynamics Cfd ◽  
Mesh Technique

A spring-loaded pressure safety valve (PSV) is a key device used to protect pressure vessels and systems. This paper developed a three-dimensional computational fluid dynamics (CFD) model in combination with a dynamics equation to study the fluid characteristics and dynamic behavior of a spring-loaded PSV. The CFD model, which includes unsteady analysis and a moving mesh technique, was developed to predict the flow field through the valve and calculate the flow force acting on the disk versus time. To overcome the limitation that the moving mesh technique in the commercial software program ANSYS CFX (Version 11.0, ANSYS, Inc., USA) cannot handle complex configurations in most applications, some novel techniques of mesh generation and modeling were used to ensure that the valve disk can move upward and downward successfully without negative mesh error. Subsequently, several constant inlet pressure loads were applied to the developed model. Response parameters, including the displacement of the disk, mass flow through the valve, and fluid force applied on the disk, were obtained and compared with the study of the behavior of the PSV under different overpressure conditions. In addition, the modeling approach could be useful for valve designers attempting to optimize spring-loaded PSVs.

Numerical Modeling of Berm Breakwater Optimization With Varying Berm Geometry Using REEF3D

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Athul Sasikumar ◽  
Arun Kamath ◽  
Onno Musch ◽  
Hans Bihs ◽  
Øivind A. Arntsen
Keyword(s):  
Numerical Model ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Flow Through Porous Media ◽  
Cfd Model ◽  
Production Chain ◽  
Offshore Production ◽  
Physical Model Tests ◽  
Computational Fluid Dynamics Cfd ◽  
Flow Through

Harbors are important infrastructures for an offshore production chain. These harbors are protected from the actions of sea by breakwaters to ensure safe loading, unloading of vessels and also to protect the infrastructure. In current literature, research regarding the design of these structures is majorly based on physical model tests. In this study a new tool, a three-dimensional (3D) numerical model is introduced. The open-source computational fluid dynamics (CFD) model REEF3D is used to study the design of berm breakwaters. The model uses the Volume-averaged Reynolds-averaged Navier-Stokes (VRANS) equations to solve the porous flows. At first, the VRANS approach in REEF3D is validated for flow through porous media. A dam break case is simulated and comparisons are made for the free surface both inside and outside the porous medium. The numerical model REEF3D is applied to show how to extend the database obtained with purely numerical results, simulating different structural alternatives for the berm in a berm breakwater. Different simulations are conducted with varying berm geometry. The influence of the berm geometry on the pore pressure and velocities are studied. The resulting optimal berm geometry is compared to the geometry according to empirical formulations.

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