A Modeling and Design Study on the Determination of the Most Influential Parameters on the Industrial Furnaces Performance (original) (raw)
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CFD analysis of heavy fuel oil combustion in a 6.7 MW cylindrical vertically- fired furnace has been carried out. The furnace supplies process heat in the Oil refinery of the National oil company (INA) in Rijeka-Croatia. The motivation of the work was to improve the performance of the combustion process by changing fuel and burner parameters. The commercial CFD-code Fluent is used to model transport and reaction in the furnace. The chosen CFD models for heavy fuel oil spray combustion are compared with measurement data found in the literature and good agreement is achieved. The combustion process is investigated through the influence of different parameters: air excess ratio, fuel oil droplet diameter, spray cone half-angle and burner swirl number. It is determined that the best performance of the combustion process is achieved for an air excess ratio of 1.15. The droplet diameter should be neither too small nor too large: medium-sized droplets (~100 μm) mix well with air and reside...
Procedia Engineering, 2016
An integrated heat transfer modeling of vertical-cylindrical refinery furnaces was carried out to determine the influential parameters on the fired heaters efficiency as well as the process and flue gas temperature variations. The model was developed considering separate sections of the heater encompassing heat of the flue gas. The model was solved by an iterative procedure with initial boundary conditions. The developed model along with its solution was compiled in MATLAB R2013a environment. The parameters involved into the devised model form the basis for the determination of the most influential parameters on the performance of fired heaters. The sensitivity analysis was accomplished via examining five parameters including excess air, tube pitch, inlet air temperature, fuel composition, and fuel flow rate. Model validation reveals that the model results reasonably agree with the experimental data with less than 4% deviation. The sensitivity analysis demonstrated that varying the five influential parameters by 5% from a base case altered the furnace efficiency by 2.69%, 0.93%, 0.22%, 0.21%, and 0.07%, respectively. The devised model can be employed to reduce computing time and technical costs afforded by the use of computational fluid dynamics (CFD) analysis.
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The efficiency of combustion in furnaces is the measure of heat released in the flame absorbed by the fluid to be heated and is considered one of the most important variables when conducting studies on processes that occur in continuous process industries. The furnace efficiency is calculated using various mathematical models proposed in the literature; these models vary in complexity depending on the analyzed variables. The models I and II are based on the amount of energy absorbed by the furnace using the heating value, the model III contains variables such as air excess, stack gas temperature and adiabatic flame temperature, meanwhile the model IV contains heating losses in furnace's wall (2%), the stack gas temperature and excess air. In this paper was used computer simulation to evaluate fuel gas mixtures with Lower Heating Values (LHV) between 800 to 2500 Btu/ft 3 , and they were compared with natural gas and data process; the results show that the combustion characteristics might change by varying the fuel composition. It was also found decreased combustion efficiency due to high hydrogen concentration; on the other hand the adiabatic flame temperature was increased in function of gas composition. Model IV presented in this research allowed evaluating combustion process efficiency using only two variables: stack gas temperature and the excess air.
Effect of burners configuration on performance of heat treatment furnaces
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In order to obtain the most uniform temperature of the load, heat transfer in heat treatment furnaces used in the steel industry was studied. Different two-equation turbulence models were compared with experimental results. The Realizable k-e model, predicts the load center line temperature better than the other two models, and it agrees closer to the experimental data. Also, by considering the radiation effect in the numerical simulation, the results were improved by 33% compared with experimental data. Finally, from different configurations of the burners studied and the results showed that the best temperature uniformity would be achieved for the configuration when the burners were located in a three down-three up arrangement.
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Industries, which are mainly responsible for high energy consumptions, need to invest in research projects in order to develop new managing systems for rational energy use and to tackle the devastating effects of climate change caused by human behavior. The study reported in this paper concerns the forging industry, where the production processes generally start with the heating of the steel in furnaces and continue with other processes, such as heat treatments and mechanical machining. One of the most critical operations, in terms of energy loss, is the opening of the furnace doors for the insertion and extraction operations. During this time, the temperature of the furnaces decreases by hundreds of degrees in a few minutes. Because the dispersed heat needs to be supplied again through the combustion of fuel, increasing the consumption of energy and the pollutant emissions, the evaluation of the amount of the lost energy is crucial for the development of operating or mechanical sys...
Theory and Calculation of Heat Transfer in Furnaces
This book and the individual contributions contained in it are protected under copyright by the Publisher (other than as may be noted herein). Notices Knowledge and best practice in this field are constantly changing. As new research and experience broaden our understanding, changes in research methods, professional practices, or medical treatment may become necessary. Practitioners and researchers must always rely on their own experience and knowledge in evaluating and using any information, methods, compounds, or experiments described herein. In using such information or methods they should be mindful of their own safety and the safety of others, including parties for whom they have a professional responsibility.
Mathematical model for refinery furnaces simulation
a mathematical model for simulation of refinery furnaces is proposed. It consists of two different submodels, one for the process side and another for the flue gas side. The process side is appropriately modeled as a plug flow due to the high velocity of the fluid inside the tubes. The flue gas side is composed by a radiative chamber and a convective section both connected by a shield tube zone. Both models are connected by the tube surface temperature. As the flue gas side model uses this temperature as input data, the process side model recalculates this temperature. The procedure is executed until certain tolerance is achieved. This mathematical model has proved to be a useful tool for furnace analysis and simulation.
Modeling and parametric studies of heat transfer in a direct-fired batch reheating furnace
Journal of Heat Treating, 1990
A mathematical systems model of a batch reheating furnace has been developed to assist the furnace design and heat treatment engineer. The furnace was modeled as a well-stirred enclosure with one-dimensional transient heat conduction in the refractory walls and the load. The convective heat transfer rate to the load and refractory was calculated by using existing correlations from the literature. The radiative heat transfer rate to the load was calculated using Hottel's zone method by considering the radiant energy exchange between the load, combustion gases, and the refractories. The directed-flux exchange areas were calculated using a four-gray gas model to treat the combustion gases as a nongray emitting and absorbing medium. An extensive parametric investigation has been completed to determine the furnace design and operating characteristics that lead to optimum furnace efficiency. The parametric investigations included in this paper were used to study the effect of the load and refractory emissivities, load heat capacity, and fuel firing rate and direction on the thermal performance of a direct-fired furnace.
2005
This is the extended second Semiannual Technical Report for DOE Cooperative Agreement No: DE-FC26-02NT41580. The goal of this project is to systematically assess the sensitivity of furnace operational conditions to burner air and fuel flows in coal fired utility boilers. Our approach is to utilize existing baseline furnace models that have been constructed using Reaction Engineering International's (REI) computational fluid dynamics (CFD) software. Using CFD analyses provides the ability to carry out a carefully controlled virtual experiment to characterize the sensitivity of NOx emissions, unburned carbon (UBC), furnace exit CO (FECO), furnace exit temperature (FEGT), and waterwall deposition to burner flow controls. The Electric Power Research Institute (EPRI) is providing co-funding for this program, and instrument and controls experts from EPRI's Instrument and Controls (I&C) Center are active participants in this project. This program contains multiple tasks and good progress is being made on all fronts. Highlights of the first year of the project include: