TWO - DIMENSIONAL COMPUTATIONAL FLUID DYNAMIC SIMULATION OF COMBUSTION OF SYNGAS AND HYDROGEN IN ROTARY KILN

• Main Author: Tandoko, Nicolas
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/80413
• Institution: Institut Teknologi Bandung

RKEF technology is used to process nickel saprolite ore where coal or syngas is genarally used as a fuel due to availability and economic factor. Combustion process using hydrogen gas is claimed to reduce direct emission of carbon gas towards the atmosphere. Therefore, it’s usage as a fuel for the rotary kiln is worth to be considered. Two dimensional Computational Fluid Dynamic simulations of syngas and hydrogen combustion with varying the addition of air and solids in a rotary kiln (diameter = 3.6 m and length = 72 m) have been carried out to compare the performance between the two fuels. Two dimensional geometry was created using Inventor Professional 2023, then imported into ANSYS Fluent, and refined using ANSYS Design Modeler. The meshing process and main parameter settings are then carried out to obtain optimum conditions. Initialization and calculations with 500 iterations were carried out to obtain simulation results in the form of temperature distribution of gas and solid. Simulation of syngas combustion at a solid feed rate of 40.39 ton/hour and syngas feed rate of 60 m3-fuel/ton-solid shows maximum gas temperatures in the burner of 1223 ?, 1080 ? and 845 ? at air variations of 1, 0.75 and 0.5 from stoichiometric requirements. When adding air of 0.75 from stoichiometric requirements, the maximum gas temperature in the burner drops to 1079 ? at a syngas feed rate of 30 m3-fuel/ton-solid. When adding air of 0.75 from stoichiometric requirements, the gas temperature along the burner to the gas outlet of the rotary kiln decreases until it reaches 510 – 660 ?, while the solids temperature in the opposite direction increases from room temperature to a maximum of 680 ? around the burner area. The simulation results of hydrogen combustion at a solid feed rate of 40.39 ton/hour and hydrogen feed rate of 25 m3-fuel/ton-solid show that the maximum gas temperature in the burner is 2187 ?, 1987 ?, and 1497 ? at air variations of 1, 0.75 and 0.5 from stoichiometric requirements. At an air addition of 0.75 from stoichiometric requirements, reducing the hydrogen feed rate to 12 m3-fuel/ton-solid reduces the maximum gas temperature to reach 1373 ?. When adding air of 0.75 stoichiometric requirements, the gas temperature along the burner to the rotary kiln gas outlet decreases until it reaches 733 – 901 ?. In general, the hydrogen combustion simulation results show a higher gas temperature than syngas combustion at a much lower amount of fuel addition.