scholarly journals CFD-modeling of fume formation in kraft recovery boilers

TAPPI Journal ◽  
2013 ◽  
Vol 12 (3) ◽  
pp. 25-32 ◽  
Author(s):  
AINO LEPPÄNEN ◽  
ERKKI VÄLIMÄKI ◽  
ANTTI OKSANEN ◽  
HONGHI TRAN
Keyword(s):  
Field Measurements ◽  
Enrichment Factors ◽  
Cfd Modeling ◽  
Cfd Model ◽  
Metal Chemistry ◽  
Kraft Recovery Boilers ◽  
Recovery Boilers ◽  
Computational Fluid Dynamics Cfd ◽  
Potassium Enrichment ◽  
Particle Mass Concentration

A computational fluid dynamics (CFD) model was developed to simulate alkali metal chemistry and fume particle formation in a kraft recovery boiler. The modeling results were partially validated against previously obtained field measurements. The model provides information about fume composition, chlorine and potassium enrichment factors, and particle mass concentration at different locations in the boiler.

Recovery boiler sootblowers: History and technological advances

TAPPI Journal ◽  
2015 ◽  
Vol 14 (1) ◽  
pp. 51-60
Author(s):  
HONGHI TRAN ◽  
DANNY TANDRA
Keyword(s):  
Cfd Modeling ◽  
Computing Systems ◽  
The Past ◽  
Technological Advances ◽  
Recovery Boilers ◽  
Computational Fluid Dynamics Cfd ◽  
Recovery Boiler ◽  
Steam Parameters ◽  
Insight Into ◽  
Deposit Removal

Sootblowing technology used in recovery boilers originated from that used in coal-fired boilers. It started with manual cleaning with hand lancing and hand blowing, and evolved slowly into online sootblowing using retractable sootblowers. Since 1991, intensive research and development has focused on sootblowing jet fundamentals and deposit removal in recovery boilers. The results have provided much insight into sootblower jet hydrodynamics, how a sootblower jet interacts with tubes and deposits, and factors influencing its deposit removal efficiency, and have led to two important innovations: fully-expanded sootblower nozzles that are used in virtually all recovery boilers today, and the low pressure sootblowing technology that has been implemented in several new recovery boilers. The availability of powerful computing systems, superfast microprocessors and data acquisition systems, and versatile computational fluid dynamics (CFD) modeling capability in the past two decades has also contributed greatly to the advancement of sootblowing technology. High quality infrared inspection cameras have enabled mills to inspect the deposit buildup conditions in the boiler during operation, and helped identify problems with sootblower lance swinging and superheater platens and boiler bank tube vibrations. As the recovery boiler firing capacity and steam parameters have increased markedly in recent years, sootblowers have become larger and longer, and this can present a challenge in terms of both sootblower design and operation.

CFD Modeling and Simulation of a Catalytic Micro-Monolith

2011 ◽  
Vol 9 (1) ◽  
Author(s):  
Almerinda Di Benedetto ◽  
Valeria Di Sarli
Keyword(s):  
Mass Flow ◽  
Single Channel ◽  
Cfd Modeling ◽  
Cfd Model ◽  
Gas Velocity ◽  
Fuel Conversion ◽  
Flow Rates ◽  
Cpu Time ◽  
Mass Flow Rates ◽  
Computational Fluid Dynamics Cfd

In this work, a first step in modeling and simulating the thermal behavior of an entire catalytic micro-monolith was performed. In particular, a Computational Fluid Dynamics (CFD) model was developed for simulating three-channel and five-channel micro-combustors. For both configurations, the operating maps were built as functions of the inlet gas velocity and compared to the operating map of a single-channel configuration.Results show that, due to the relevance of heat losses in micro-devices, it is not possible to extrapolate the behavior of the multi-channel configurations from that of the single channel. Therefore, simulation of the entire catalytic micro-monolith is needed. However, this is computationally demanding: it has been found that the CPU time almost linearly increases with the number of channels simulated.Finally, for a fixed total mass flow rate, it has been demonstrated the opportunity to maximize the overall fuel conversion by means of a non-uniform distribution of mass flow rates among the channels.

Hydrodynamic evaluation of a full-scale facultative pond by computational fluid dynamics (CFD) and field measurements

2014 ◽  
Vol 70 (3) ◽  
pp. 569-575 ◽  
Author(s):  
Ricardo Gomes Passos ◽  
Marcos von Sperling ◽  
Thiago Bressani Ribeiro
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Short Circuit ◽  
Field Measurements ◽  
Tracer Test ◽  
Full Scale ◽  
Cfd Model ◽  
Cfd Modelling ◽  
Hydraulic Behaviour ◽  
Computational Fluid Dynamics Cfd

Knowledge of the hydraulic behaviour is very important in the characterization of a stabilization pond, since pond hydrodynamics plays a fundamental role in treatment efficiency. An advanced hydrodynamics characterization may be achieved by carrying out measurements with tracers, dyes and drogues or using mathematical simulation employing computational fluid dynamics (CFD). The current study involved experimental determinations and mathematical simulations of a full-scale facultative pond in Brazil. A 3D CFD model showed major flow lines, degree of dispersion, dead zones and short circuit regions in the pond. Drogue tracking, wind measurements and dye dispersion were also used in order to obtain information about the actual flow in the pond and as a means of assessing the performance of the CFD model. The drogue, designed and built as part of this research, and which included a geographical positioning system (GPS), presented very satisfactory results. The CFD modelling has proven to be very useful in the evaluation of the hydrodynamic conditions of the facultative pond. A virtual tracer test allowed an estimation of the real mean hydraulic retention time and mixing conditions in the pond. The computational model in CFD corresponded well to what was verified in the field.

scholarly journals The Effect of Tree-Planting Patterns on the Microclimate within a Courtyard

2019 ◽  
Vol 11 (6) ◽  
pp. 1665 ◽  
Author(s):  
Junying Li ◽  
Jiying Liu ◽  
Jelena Srebric ◽  
Yuanman Hu ◽  
Miao Liu ◽  
...  
Keyword(s):  
Air Temperature ◽  
Local Heat Transfer ◽  
Field Measurements ◽  
Weather Conditions ◽  
Local Heat ◽  
Tree Planting ◽  
Cfd Model ◽  
Planting Pattern ◽  
Wind Velocities ◽  
Computational Fluid Dynamics Cfd

Current landscape design within a courtyard usually does not take into account the influence of the tree-planting pattern, which has an important influence on the outdoor microclimate and occupants’ thermal comfort. At present, the extent of the influence on the microclimate has not yet been made clear. Computational Fluid Dynamics (CFD) was employed to run this model under hot summer weather conditions. Field measurements validated the performance of the CFD model. This study conducted numerical simulations for five different tree-planting patterns, including (i) focused tree-planting (F), (ii) cornered tree-planting (C), (iii) multi-row tree-planting (R), (iv) surround tree-planting (S) and (v) no tree-planting (N). Our study found that the tree-planting pattern affects both the distribution of air temperature and the degree of local heat transfer. Specifically, the C, S and N patterns allow for higher ventilation in the studied courtyard, while the F and R patterns cause lower wind velocities and associated courtyard ventilation. The average air temperature for the C pattern is lower during summer afternoons than the other patterns. The wind flow pattern in the studied courtyard does not vary significantly with different tree-planting patterns. Nevertheless, the general relative humidity in the courtyard does not vary significantly with different tree-planting patterns, except for the N pattern. A future analysis is needed to investigate the mechanisms of the phenomenon.

Simulation of Thermal Comfort Conditions of an Air-Conditioned Cafeteria in the Tropics

2014 ◽  
Vol 564 ◽  
pp. 263-268
Author(s):  
A. Zainuddin ◽  
Nor Maria Adam ◽  
I.H. Rusli ◽  
Qi Jie Kwong
Keyword(s):  
Thermal Comfort ◽  
Air Temperature ◽  
Field Measurements ◽  
Cfd Modeling ◽  
Airflow Rate ◽  
Computational Fluid Dynamics Cfd ◽  
Predicted Values ◽  
The Tropics ◽  
Comfort Parameters ◽  
Indoor Comfort

This paper studies the current thermal comfort condition of an air-conditioned cafeteria based on objective measurements and computational fluid dynamics (CFD) modeling. Indoor comfort parameters such as temperature and airflow rate were simulated by a CFD tool. The results from field measurements and predicted values were then compared and contrasted. A simulated model that has the same geometrical configuration as the cafeteria was set as a benchmark model. Several additional models with different configuration of cafeteria layouts were proposed to achieve the required air temperature. It was found that the predicted results from the proposed models showed even distributions of airflow characteristics and temperature gradients. To maintain a thermally-acceptable air temperature of 28 °C, it is proposed that an additional air-conditioning unit be retrofitted to the current cafeteria layout.

scholarly journals 3D computational fluid dynamics modeling of temperature and humidity in a humidified greenhouse

2021 ◽  
Vol 13 (1) ◽  
pp. 17-31
Author(s):  
Cuauhtémoc Pérez-Vega ◽  
◽  
José Armando Ramírez-Arias ◽  
Irineo L. López-Cruz ◽  
Ramón Arteaga-Ramírez ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Natural Ventilation ◽  
Temporal Distribution ◽  
Cfd Modeling ◽  
Cfd Model ◽  
Dynamics Modeling ◽  
Temperature And Humidity ◽  
Humidity Measurements ◽  
Computational Fluid Dynamics Cfd

Introduction: Medium and low technology greenhouses use natural ventilation as a method of temperature and humidity control. However, at certain times of the year, this is insufficient to extract excess heat inside the greenhouse, so devices such as hydrophanes (humidifiers) have been implemented to reduce the temperature. It is necessary to know the behavior of temperature and humidity, since both factors influence the development of crops and, therefore, their yield. Objective: To develop a computational fluid dynamics (CFD) model of a naturally ventilated zenithal greenhouse equipped with hydrophanes to understand the spatial and temporal distribution of temperature and humidity inside the greenhouse. Methodology: The experiment was carried out in a greenhouse equipped with hydrophanes and grown with bell pepper. Temperature and humidity measurements were performed from March 7 to 25, 2014. The ANSYS Workbench program was used for the 3D CFD modeling. Results: The CFD model satisfactorily described the temperature and humidity distribution of the greenhouse, with an error of 0.11 to 3.43 °C for temperature, and 0.44 to 10.80 % for humidity. Limitations of the study: Numerical modeling using CFD is inadequate to model the temporality of the variables. Originality: There are few studies that model humidity behavior with CFD and the use of hydrophanes in Mexico. Conclusions: The CFD model allowed visualizing the distribution of temperature and air humidity inside the greenhouse.

Air port flow patterns in kraft recovery boilers

1996 ◽  
Vol 11 (2) ◽  
pp. 115-120
Author(s):  
D.C.S. Kuhn ◽  
T. Mao ◽  
H.N. Tran
Keyword(s):  
Flow Patterns ◽  
Kraft Recovery Boilers ◽  
Recovery Boilers

Effects of Over Fire Air on the Combustion and NOx Emission Characteristics of a 600 MW Opposed Swirling Fired Boiler

2012 ◽  
Vol 512-515 ◽  
pp. 2135-2142 ◽  
Author(s):  
Yu Peng Wu ◽  
Zhi Yong Wen ◽  
Yue Liang Shen ◽  
Qing Yan Fang ◽  
Cheng Zhang ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Empirical Method ◽  
Nox Emission ◽  
Emission Characteristics ◽  
Cfd Model ◽  
Nitrogen Release ◽  
Computational Fluid Dynamics Cfd ◽  
Low Nox Emission

A computational fluid dynamics (CFD) model of a 600 MW opposed swirling coal-fired utility boiler has been established. The chemical percolation devolatilization (CPD) model, instead of an empirical method, has been adapted to predict the nitrogen release during the devolatilization. The current CFD model has been validated by comparing the simulated results with the experimental data obtained from the boiler for case study. The validated CFD model is then applied to study the effects of ratio of over fire air (OFA) on the combustion and nitrogen oxides (NOx) emission characteristics. It is found that, with increasing the ratio of OFA, the carbon content in fly ash increases linearly, and the NOx emission reduces largely. The OFA ratio of 30% is optimal for both high burnout of pulverized coal and low NOx emission. The present study provides helpful information for understanding and optimizing the combustion of the studied boiler

scholarly journals Computational Investigation of Inclusion Removal in the Steel-Refining Ladle Process

Processes ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 1048
Author(s):  
Xipeng Guo ◽  
Joel Godinez ◽  
Nicholas J. Walla ◽  
Armin K. Silaen ◽  
Helmut Oltmann ◽  
...  
Keyword(s):  
Multiphase Flow ◽  
Porous Plug ◽  
Cfd Modeling ◽  
Balance Model ◽  
Computational Investigation ◽  
Inclusion Removal ◽  
Inclusion Interaction ◽  
Computational Fluid Dynamics Cfd ◽  
Steel Refining ◽  
Transient Multiphase Flow

In a steel-refining ladle, the properties of manufactured steel can be notably degraded due to the presence of excessive inclusions. Stirring via gas injection through a porous plug is often used as part of the steel-refining process to reduce these inclusions. In this paper, 3D computational fluid dynamics (CFD) modeling is used to analyze transient multiphase flow and inclusion removal in a gas-stirred ladle. The effects of gas stirring with bubble-inclusion interaction are analyzed using the Euler–Euler approach for multiphase flow modeling, while the effects of inclusions aggregation and removal are modeled via a population balance model (PBM).

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