Master Thesis on "Modelling of Rotary Kiln Burner Using Heavy Fuel Oil and Natural Gas for Al-Hadbaa Cement Plant"
A master thesis was discussed in Department of Mechanical Engineering / College of Engineering at University of Mosul entitled "Modelling of Rotary Kiln Burner Using Heavy Fuel Oil and Natural Gas for Al-Hadbaa Cement Plant" submitted by (Anmar Yousif Mahmoud Mohammed), Supervised By Assist. Prof. Dr. Abdulrahman Habbo Mohammed Alhabbo on Wednesday, June 01, 2022.
The thesis dealt with a theory of natural gas and heavy fuel oil combustion and making comparison between them in the cement plants. The kiln burner of Alhadbaa Cement plant was selected as a model for this study. The research included two axes, the first axis was represented by a one-dimensional study using ANSYS CHEMKIN engineering software to study the temperature, laminar flame speed, the amount of the net heat released and the amount of emissions for nitrogen oxides and carbon oxides for each fuel and then comparing them when the equivalence ratio is (0.7 – 1.2), and the reactants temperature is (300-400) kelvins and when the pressure of the reactants is (1 – 10) atmosphere.
The results showed that temperature, laminar flame speed and the amount of heat released reach the highest values when the equivalence ratio is approaching to the stoichiometric value (1) and these values decrease when the equivalence ratio is lower or higher than the stoichiometric value, i.e. when the mixture is weak or rich for both types of the fuels. On the other hand, the laminar flame speed is inversely related with the pressure and directly related with the reactants temperature. Also, results showed that the flame temperature and the amount of heat released increase with the increase of the temperature and the pressure of the reactants for both of the fuels too. The current research also, showed that the flame temperature, laminar flame speed and the amount of the released heat of the heavy fuel oil are higher than the natural gas with percentages of 2%, 35% and 50% respectively when the equivalence ratio is (1) and the reactants pressure is (1) atmosphere and when the reactants temperature is (300) kelvin. As for the emissions, results showed that the amounts of nitrogen oxide and carbon monoxide of the heavy fuel oil are much higher than the amounts of emissions of the natural gas, with percentages of 40% and 46% respectively for the same combustion conditions of the equivalence ratio, temperature and pressure.
The two-dimensional results demonstrated that the spread of the flame in the case of the natural gas was higher than in the heavy fuel oil and that the flame temperature of the heavy fuel oil was higher than the flame temperature of the natural gas with a percentage of 6.4%. When doubling the input amount of fuel for combustion The percentage between the two fuels reaches to 4.8%. Concerning the amounts of emission resulting from each fuel, results showed that the percentages of emissions of nitrogen oxide, carbon monoxide and soot for the heavy fuel oil were higher than their counterparts for the natural gas, with percentages of 70%, 37% and 80% respectively.
Therefore, the thesis indicated the possibility of replacing the heavy fuel oil with the natural gas due to the characteristics mentioned above especially in terms of decreasing the emissions of nitrogen oxide and carbon monoxide, which are part of the industrial countries requirements to limit the high emission phenomenon that has a negative impact on the environment.