Using CFD to Model Coal Roping Phenomenon in Coal Transport Systems

2004 ◽  
Author(s):  
Gengxun Huang ◽  
Kenneth M. Bryden ◽  
Edmundo Vasquez ◽  
Ravikanth Avancha
Keyword(s):  
Cross Section ◽  
Pulverized Coal ◽  
Plant Performance ◽  
Transport Systems ◽  
Phase Flow ◽  
Centrifugal Forces ◽  
Cfd Model ◽  
Two Phase ◽  
Number Of Factors ◽  
Coal Injection

Coal roping is a well-known phenomenon occurring in pneumatic transport of pulverized coal. In coal roping the majority of the coal is concentrated in a small portion of the transport piping cross section. This region of concentrated solid flow is created by a number of factors. For example, as the two phase flow of air and coal travels through an elbow or turn in the coal transport piping the centrifugal forces exerted on the coal concentrate the coal on the outside edge of the elbow. After the coal rope is formed these particles will tend to travel together. Coal roping upstream of a coal distributor (bifuractor) can create a significant imbalance in coal loading between in the split between the two branches. This can result in unbalance coal loading between burners and ununiform coal injection in plant burners. This can significantly impact plant performance and increase NOx production. This paper examines how CFD model can be used to understand common creation and breakup mechanisms of coal roping.

Measuring Flow Pattern Asymmetry of Oil-Water Two Phase Flows Using Multi-channel Rotating Electric Field Conductance Signals

2018 ◽  
Vol 74 (1) ◽  
pp. 25-41 ◽  
Author(s):  
Yuansheng He ◽  
Yingyu Ren ◽  
Yunfeng Han ◽  
Ningde Jin
Keyword(s):  
Electric Field ◽  
Flow Pattern ◽  
Cross Section ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Time Asymmetry ◽  
Pipe Cross Section ◽  
Multi Scale ◽  
Oil Water

AbstractThe present study is a report on the asymmetry of dispersed oil phase in vertical upward oil-water two phase flow. The multi-channel signals of the rotating electric field conductance sensor with eight electrodes are collected in a 20-mm inner diameter pipe, and typical images of low pattern are captured using a high speed camera. With the multi-channel rotating electric field conductance signals collected at pipe cross section, multi-scale time asymmetry (MSA) and an algorithm of multi-scale first-order difference scatter plot are employed to uncover the fluid dynamics of oil-water two phase flow. The results indicate that MSA can characterise the non-linear behaviours of oil-water two phase flow. Besides, the MSA analysis also beneficial for understanding the underlying inhomogeneous distribution of the flow pattern in different directions at pipe cross section.

Simulation of Pulverized Coal Injection in a Blast Furnace

2006 ◽  
Author(s):  
Mingyan Gu ◽  
Zumao Chen ◽  
Naresh K. Selvarasu ◽  
D. Huang ◽  
Pinakin Chaubal ◽  
...  
Keyword(s):  
Blast Furnace ◽  
Three Dimensional ◽  
Coal Mass ◽  
Pulverized Coal ◽  
Cfd Model ◽  
Mass Distributions ◽  
Pulverized Coal Injection ◽  
Fluid Flow Velocity ◽  
Coal Injection ◽  
Parametric Studies

A three-dimensional multiphase CFD model using an Eulerian approach is developed to simulate the process of pulverized coal injection into a blast furnace. The model provides the detailed fields of fluid flow velocity, temperatures, and compositions, as well as coal mass distributions during the devolatilization and combustion of the coal. This paper focuses on coal devolatilization and combustion in the space before entering the raceway of the blast furnace. Parametric studies have been conducted to investigate the effect of coal properties and injection operations.

Note on Relationships between Friction and Liquid Cross-Sections during Two-Phase Flow

1966 ◽  
Vol 8 (1) ◽  
pp. 107-109 ◽  
Author(s):  
D. Chisholm
Keyword(s):  
Pressure Gradient ◽  
Cross Section ◽  
Cross Sections ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Pronounced Change ◽  
Two Phase ◽  
Horizontal Tubes ◽  
A Value ◽  
Friction Pressure

Relationships between the friction pressure gradient and the cross-section of the tube occupied by the liquid are developed for the flow of air-water mixtures in rough-walled horizontal tubes. The data indicate a pronounced change in the form of the relationships when the pressure gradient reaches a value of about 60 lb/ft2ft.

scholarly journals Validation of NEPTUNE-CFD Two-Phase Flow Models Using Experimental Data

2014 ◽  
Vol 2014 ◽  
pp. 1-19 ◽  
Author(s):  
Jorge Pérez Mañes ◽  
Victor Hugo Sánchez Espinoza ◽  
Sergio Chiva Vicent ◽  
Michael Böttcher ◽  
Robert Stieglitz
Keyword(s):  
Experimental Data ◽  
Void Fraction ◽  
Two Phase Flow ◽  
Model Parameters ◽  
Phase Flow ◽  
Cfd Model ◽  
Two Phase ◽  
Flow Models ◽  
Phase Models ◽  
Good Agreement

This paper deals with the validation of the two-phase flow models of the CFD code NEPTUNEC-CFD using experimental data provided by the OECD BWR BFBT and PSBT Benchmark. Since the two-phase models of CFD codes are extensively being improved, the validation is a key step for the acceptability of such codes. The validation work is performed in the frame of the European NURISP Project and it was focused on the steady state and transient void fraction tests. The influence of different NEPTUNE-CFD model parameters on the void fraction prediction is investigated and discussed in detail. Due to the coupling of heat conduction solver SYRTHES with NEPTUNE-CFD, the description of the coupled fluid dynamics and heat transfer between the fuel rod and the fluid is improved significantly. The averaged void fraction predicted by NEPTUNE-CFD for selected PSBT and BFBT tests is in good agreement with the experimental data. Finally, areas for future improvements of the NEPTUNE-CFD code were identified, too.

scholarly journals CFD Modeling of Gas-Liquid Flow and Heat Transfer in a High Pressure Water Electrolysis System

2006 ◽  
Author(s):  
V. Agranat ◽  
S. Zhubrin ◽  
A. Maria ◽  
J. Hinatsu ◽  
M. Stemp ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Flow Rate ◽  
Liquid Flow ◽  
Liquid Flow Rate ◽  
Water Electrolysis ◽  
Phase Flow ◽  
Cfd Model ◽  
Two Phase ◽  
Pressure Water ◽  
Electrolysis System

A high-pressure water electrolysis system has been investigated numerically and experimentally. The advanced CFD model of two-phase flow, which calculated the 3D distributions of pressure, gas and liquid velocities and gas and liquid volume fractions, has been developed to account for all the major components in the system, and appropriate constitutive equations for two-phase flow parameters were selected for various parts of the system, such as the cell stack, riser, separator and downcomer. Heat transfer between the two phases, and between the gas-liquid mixture and cooling coils located in the gas-liquid separator was also accounted for. The model was validated using comparisons of predicted liquid flow rate with the liquid flow rate measured in the downcomer, where a single-phase liquid flow existed. The effects of pressure, current density, number of cells, and bubble size were investigated with the numerical model. The numerical predictions matched the general trends obtained from the experimental results with regard to the effects of pressure and current density on the liquid flow rate. The validated CFD model is being used as a cell design tool at Hydrogenics Corporation.

Two-Phase Flow Correlations in Air/Oil Systems of Aero Engines

1991 ◽  
Author(s):  
H. Zimmermann ◽  
A. Kammerer ◽  
R. Fischer ◽  
D. Rebhan
Keyword(s):  
Two Phase Flow ◽  
Phase Flow ◽  
Test Results ◽  
Centrifugal Forces ◽  
Flow Conditions ◽  
Two Phase ◽  
Oil Mixtures ◽  
Water Test ◽  
Flow Effects ◽  
Aero Engines

A strategy is outlined on how to introduce two-phase flow correlations into air/oil system calculations for aero engines. The importance of two-phase flow effects is highlighted by demonstrating their particular significance for the high altitude performance of a vent system. For air/oil mixtures very little can be obtained from the literature and correlations derived from air/water test results have to be corrected. For critical flow conditions in restrictors an improved method is developed. Some test data obtained for air/oil mixtures show, that the proposed correlations agree fairly well. Furthermore, it is shown how numerical methods for this complex field of fluid dynamics can be used in the future by the example of phase demixing by centrifugal forces.

Dryout prediction with CFD model of annular two-phase flow

2019 ◽  
Vol 349 ◽  
pp. 20-26 ◽  
Author(s):  
Haipeng Li ◽  
Henryk Anglart
Keyword(s):  
Two Phase Flow ◽  
Phase Flow ◽  
Cfd Model ◽  
Two Phase
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