جستجوی مقالات مرتبط با کلیدواژه « مشعل » در نشریات گروه « مکانیک »

In this paper, the numerical simulation of combustion in one of the industrial furnaces of Kermanshah Oil Refining Company has been carried out in order to investigate the cause of high temperature damage to its damper and provide a solution to solve this problem. At first, the current situation has been investigated. For this purpose, the numerical model of furnace and burner has been produced and numerical simulations have been carried out to check the current situation. The agreement between the actual factory data and the numerical simulation data is acceptable. In the next step, by changing the burner and changing the shape of the flame, numerical simulations have been performed in order to solve the problem. The obtained results show that by changing the burner and using 4 smaller burners but with a longer flame, the shape of the flame becomes branched and with the increase of heat transfer caused by this situation, the temperature at the place where the damper is installed decreases by about 170 degrees Celsius. This decrease in temperature can solve the problem of damaging the damper and softening the structure connecting it to the flue.
 
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In this research, the geometric parameters of a preheated furnace burner in the press line of Esfarayen Industrial Complex have been studied, experimentally and numerically. To improve the combustion process in the burner, three different diameters (10, 20 and 30 mm) are provided for the nozzle diameter and three different lengths (225, 250 and 300 mm) for the mixing length of the burner. Ansys-Fluent software and RNG k-ε turbulence model have been used for the simulation and the modeling results show that the applied method has good accuracy and with a maximum error of 23% higher than the experimental values for temperature. This temperature difference is due to the lack of accurate measurement of inlet air flow and also point measurement of temperature in the burner. In the study of the effect of nozzle diameter, it was observed that by increasing the nozzle diameter from 10 to 30 mm, the maximum temperature inside the burner increased by 6%, which against a slight increase in nitrogen oxides (Nox) pollutants inside the burner, the 30 mm diameter for optimum design is selected among the tested diameters. Also, the results of the study for the effect of mixing length on burner performance have shown that by increasing the length, the amount of heat produced decreases slightly, which due to more favorable stability of NOx pollutants due to more space and complete reaction, length of 300 mm has been chosen for optimal design of burner.

Environmental issues and air pollution have attracted a lot of attention in recent years. Thermal power plants are among the air pollutants. One of the solutions used for better combustion and less pollution in other combustion systems, including gas turbines, is the idea of ​​water vapor injection. In this study, it was considered that with the idea of ​​adding water vapor to the gas turbine, a similar work would be done in the boilers, for which in this research, a 11 Megawatts single axisymmetric burner in the form of two dimension is modeled using the open source software OpenFoam and the ReactingFoam solver. For simulation, the equations for mass, momentum, energy, and species conservation were solved together as a coupling, and the pressure corrections in the momentum equations was performed according to the PIMPLE algorithm. The model used for the turbulence is the  model, the radiation model fvDOM, the combustion model used PaSR model and the reaction mechanism GRI-3, which includes 53 species and 325 reactions. To validate the solver and the models used, a standard problem was used which is a simple burner and its experimental results are available. After proving the correctness of the solution, the mentioned problem was simulated. It was observed that in the dry air combustion chamber, the temperature and, consequently, the NOx output are high. The flame temperature decreased after the steam injection in three proportions by 5, 10, and 15% of the total inlet air, so that the temperature in the axisymmetric boiler decreased by 370 Kelvin. Also, in the axisymmetric boiler, the amount of NO output decreased 81 % and the amount of output decreased 76%. However, carbon pollutants, specifically for CO which was important in this studyincreased by 58% to 17 ppm but was still much lower than national and European standards.

The combustion system used by the Hoffman furnaces for brick factories has a very low efficiency. In the current paper, the performance of the combustion system of Hoffman furnaces of Kolet Pottery Brick Co has improved, using computational fluid dynamics (CFD) by making changes to the Hoffman furnace torch, including the converging the torch head, inserting the spring in the pipe to create the swirl flow, shortening the nozzle length for the better mixing of the fuel and air, and more. The changes were simulated in each step with the FLUENT simulation software. Based on the theoretical results and simulation, optimized torch was made and a field test was carried out on it in a brick factory and the gases from their combustion were analyzed. As a result of these reforms, the combustion efficiency of the Hoffman furnaces has increased from 27% to 47 %, and consumption of fuel oil has decreased by a third. Also, the CO value of 16854 ppm in the old torch was reduced to 298 ppm in the optimized torch and the NO value ranged from 49 to 18 ppm as a result of optimizations.