In-furnace temperature and heat flux mapping in a kraft recovery boiler

TAPPI Journal ◽  
2010 ◽  
Vol 9 (9) ◽  
pp. 7-11 ◽  
Author(s):  
ANDERS BRINK ◽  
TOR LAURÉN ◽  
MIKKO HUPA ◽  
RALF KOSCHACK ◽  
CHRISTIAN MUELLER
Keyword(s):  
Fluid Dynamics ◽  
Heat Flux ◽  
Computational Fluid Dynamics ◽  
Radiative Heat ◽  
Furnace Temperature ◽  
Ir Camera ◽  
Surface Temperatures ◽  
Validation Of Models ◽  
Recovery Boiler ◽  
Flux Probe

Gas temperatures, incident heat flux, and surface temperatures were measured in a large kraft recovery boiler. The measurements were a part of an extensive campaign planned and carried out to support validation of models based on computational fluid dynamics. The gas temperatures were measured with three different techniques: infrared (IR) pyrometer, suction pyrometer, and unshielded thermocouples. In addition to the temperature measurements, the radiative heat flux was measured in a number of locations in the boiler using a portable heat flux probe, and the surface temperatures inside the boiler were measured using a portable single-band IR camera.

CFD-modeling for more precise operation of the kraft recovery boiler

TAPPI Journal ◽  
2012 ◽  
Vol 11 (11) ◽  
pp. 19-27 ◽  
Author(s):  
MARKUS ENGBLOM ◽  
PASI MIIKKULAINEN ◽  
ANDERS BRINK ◽  
MIKKO HUPA
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
The Other ◽  
Cfd Modeling ◽  
Furnace Temperature ◽  
Model Predictions ◽  
Boiler Operation ◽  
Computational Fluid Dynamics Cfd ◽  
Recovery Boiler ◽  
Temperature Asymmetry

During kraft recovery boiler operation, situations can be encountered where the furnace temperature is asymmetric when comparing one side of the furnace to the other (i.e., left vs. right). In this paper, computational fluid dynamics (CFD) modeling is applied to study furnace load and liquor spraying as causes for asymmetric furnace temperatures in a 4450 tons dry solids (TDS)/day kraft recovery boiler. The model predictions are compared against validation measurements. Decrease in furnace load is identified as the main cause of the temperature asymmetry. The simulations also suggest that, at decreased load, relatively small differences in the tilts of individual liquor sprays can increase the temperature asymmetry.

scholarly journals Experimental and Numerical Study for the Effect of Horizontal Openings on the External Plume and Potential Fire Spread in Informal Settlements

2021 ◽  
Vol 11 (5) ◽  
pp. 2380
Author(s):  
Mohamed Beshir ◽  
Karim Omar ◽  
Felipe Roman Centeno ◽  
Samuel Stevens ◽  
Lesley Gibson ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Heat Flux ◽  
Computational Fluid Dynamics ◽  
Radiative Heat ◽  
Numerical Study ◽  
Informal Settlement ◽  
Informal Settlements ◽  
Fire Spread ◽  
Heat Fluxes ◽  
Fuel Load

According to recent UN reports, it is estimated that more than one billion people live in informal settlements globally, exposing them to a large potential fire risk. In previous research, it was found that the main fire spread mechanism between dwellings is the external flaming (plume) and radiative heat fluxes from the vertical openings at the dwelling of origin to the surroundings. In this paper, an experimental and numerical study was conducted to quantify the effect of adding horizontal roof openings to the design of informal settlement dwellings to reduce the fire spread risk by decreasing the length of flames and radiation from the external plumes at the vertical openings. In total, 19 quarter scale ISO-9705 compartment fire experiments were conducted using an identical fuel load (80 MJ/m2) of polypropylene and were used to validate a physical computational fluid dynamics model for future studies. Five different total horizontal openings areas (0.0025, 0.01, 0.04, 0.09, and 0.16 m2) were investigated using two horizontal openings designs: (1) four square openings at the four corners of the compartment and (2) one slot cut at the middle of the compartment. It was found that adding horizontal openings decreased the average heat flux measured at the door by up to 65% and 69% for corner and slot cases, respectively. Heat flux reductions were achieved at opening areas as low as 0.01 m2 for slot cases, whereas reductions were only achieved at areas of at least 0.09 m2 for corner cases. The Computational Fluid Dynamics (CFD) model was validated using the experimental results. It successfully captured the main fire dynamics within the compartment in addition to the values of the external radiative heat flux. Further, a new empirical ventilation factor was generated to describe the flow field through both openings configurations which showed strong coupling with the inlet mass of fresh air to the compartment.

A Condensed Phase Computational Fluid Dynamics Model for Polymer Melt Flow

2008 ◽  
Author(s):  
Qing Tang ◽  
Michael Bockelie
Keyword(s):  
Fluid Dynamics ◽  
Heat Flux ◽  
Computational Fluid Dynamics ◽  
Condensed Phase ◽  
Stokes Equations ◽  
Free Surface Flows ◽  
Polymer Materials ◽  
High Heat Flux ◽  
Time Step ◽  
Temperature Dependent Viscosity

This paper presents a condensed phase computational fluid dynamics (CFD) based tool for modeling the processes of melting, flow and gasification of thermoplastic materials exposed to a high heat flux. Potential applications of the tool include investigating the behavior of polymer materials commonly used in personal computers and computer monitors if exposed to an intense heat flux, such as occurs during a fire. The finite-volume based model uses a three-dimensional body-fitted time dependent grid formulation to solve the unsteady Navier Stokes equations. A multi-grid method is used to accelerate convergence at each time step. Sub-models are included to describe the temperature dependent viscosity relationship and in-depth gasification and absorption of thermoplastic materials, free surface flows and surface tension. A series of test cases have been performed and the model results are compared to experimental data to investigate the impacts of different sub-models, boundary conditions, material properties and problem configurations on the accuracy, efficiency and applicability of the modeling tool.

Computational Fluid Dynamics Modeling of Flow Boiling in Microchannels With Nonuniform Heat Flux

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Daniel Lorenzini ◽  
Yogendra K. Joshi
Keyword(s):  
Fluid Dynamics ◽  
Heat Flux ◽  
Computational Fluid Dynamics ◽  
Phase Change ◽  
Two Phase Flow ◽  
Flow Boiling ◽  
Cfd Modeling ◽  
Temperature Phase ◽  
Phase Flow ◽  
Two Phase

The computational fluid dynamics (CFD) modeling of boiling phenomena has remained a challenge due to numerical limitations for accurately simulating the two-phase flow and phase-change processes. In the present investigation, a CFD approach for such analysis is described using a three-dimensional (3D) volume of fluid (VOF) model coupled with a phase-change model accounting for the interfacial mass and energy transfer. This type of modeling allows the transient analysis of flow boiling mechanisms, while providing the ability to visualize in detail temperature, phase, and pressure distributions for microscale applications with affordable computational resources. Results for a plain microchannel are validated against benchmark correlations for heat transfer (HT) coefficients and pressure drop as a function of the heat flux and mass flux. Furthermore, the model is used for the assessment of two-phase cooling in microelectronics under a realistic scenario with nonuniform heat fluxes at localized regions of a silicon microchannel, relevant to the cooling layer of 3D integrated circuit (IC) architectures. Results indicate the strong effect of two-phase flow regime evolution and vapor accumulation on HT. The effects of reduced saturation pressure, subcooling, and flow arrangement are explored in order to provide insight about the underlying physics and cooling performance.

Improved Thermal Insulation for Contemporary Automotive Roof Structures Based on a Computational Fluid Dynamics Heat Flux Approach

2016 ◽  
Vol 37 (16) ◽  
pp. 1418-1426
Author(s):  
Steffen Wirth ◽  
Frank Niebling ◽  
Umashankar Logasanjeevi ◽  
Vijay Premchandran
Keyword(s):  
Fluid Dynamics ◽  
Heat Flux ◽  
Computational Fluid Dynamics ◽  
Thermal Insulation

scholarly journals Integrated study of flue gas flow and superheating process in a recovery boiler using computational fluid dynamics and 1D-process modeling

TAPPI Journal ◽  
2020 ◽  
Vol 19 (6) ◽  
pp. 303-316
Author(s):  
KUNAL KUMAR ◽  
VILJAMI MAAKALA ◽  
VILLE VUORINEN
Keyword(s):  
Fluid Dynamics ◽  
Heat Flux ◽  
Computational Fluid Dynamics ◽  
Temperature Distribution ◽  
Flue Gas ◽  
Gas Flow ◽  
Flux Distribution ◽  
Heat Flux Distribution ◽  
Recovery Boilers ◽  
Material Temperature

Superheaters are the last heat exchangers on the steam side in recovery boilers. They are typically made of expensive materials due to the high steam temperature and risks associated with ash-induced corrosion. Therefore, detailed knowledge about the steam properties and material temperature distribution is essential for improving the energy efficiency, cost efficiency, and safety of recovery boilers. In this work, for the first time, a comprehensive one-dimensional (1D) process model (1D-PM) for a superheated steam cycle is developed and linked with a full-scale three-dimensional (3D) computational fluid dynamics (CFD) model of the superheater region flue gas flow. The results indicate that: (1) the geometries of headers and superheater platens affect platen-wise steam mass flow rate distribution (3%–7%); and (2) the CFD solution of the 3D flue gas flow field and platen heat flux distribution coupled with the 1D-PM affect the platen-wise steam superheating temperature (45%–122%) and material temperature distribution (1%–6%). Moreover, it is also found that the commonly-used uniform heat flux distribution approach for the superheating process is not accurate, as it does not consider the effect of flue gas flow field in the superheater region. These new observations clearly demonstrate the value of the present integrated CFD/1D-PM modeling approach.

scholarly journals THERMAL AND COMPUTATIONAL FLUID DYNAMICS ANALYSIS OF AN OIL FIRED CRUCIBLE FURNACE DURING SECONDARY ALUMINUM SMELTING

2020 ◽  
Vol 23 (2) ◽  
pp. 21-27
Author(s):  
Oluwasegun Biodun Owolabi ◽  
◽  
Lawrence Opeyemi Osoba ◽  
Samson Oluropo Adeosun ◽  
◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Heat Flux ◽  
Computational Fluid Dynamics ◽  
Cfd Simulation ◽  
Theoretical Calculations ◽  
Secondary Aluminum ◽  
Maximum Heat ◽  
Computational Fluid Dynamics Analysis ◽  
Crucible Furnace ◽  
Solid Works

Thermal and computational fluid dynamics (CFD) analysis were explore with knowledge based software such as Solid Works and ANSYS workbench 14.0 for modeling and simulation of an Oil fired crucible furnace used for aluminum secondary smelting. Thermal analysis gives the maximum heat flux and directional heat flux as 8.7596W/mm2 and 8.0349 W/mm2 respectively. CFD simulation shows that the effect of the process parameter on the furnace components is as a result of furnace factors. In brevity theoretical calculations of thermal stress up in the furnace and heat transfer to crucible conform to the modelled results.

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