Methane is a clean gaseous fuel used in chemical industries worldwide. 1000 kmol
ID: 1067187 • Letter: M
Question
Methane is a clean gaseous fuel used in chemical industries worldwide. 1000 kmol/hr of methane is combusted in a burner to provide heat. The combustion reaction is: CH4 + O2 à CO2 + H2O Air is used for combustion and it can be assumed to be composed of 20% oxygen and 80% nitrogen. Nitrogen is considered inert and does not undergo any oxidation reaction. The inlet pressure for all stream is atmospheric. Use a conversion reactor in VMGSim simulation package to simulate burner. Assume that the heat loss to surrounding is negligible (very well insulated burner). Pressure drop across the burner is assumed to be 10 kPa. Assume adiabatic conditions with methane conversion of 95%. Follow the simulation guideline (to be provided) and having converged the simulation, export the results to WORD. The followings can be easily determined from the results: 1- Properties of exhaust gases such as average specific heat, enthalpy, entropy, thermal conductivity, viscosity etc. 2- Composition of exhaust gases from the burner in mole% and mass% 3- The flow rate of each component in the exhaust gas in Kg/h 4- Temperature of exhaust gases 5- Pressure of exhaust gases 6- Volumetric flow rate of gases Now repeat the simulation assuming the you use 50% excess air. You need to increase the mole fraction in the inlet stream to burner. Keeping all other conditions the same, compare the results of the two simulation and answer the following questions in the report. You may add these to the report (exported to WORD). 1- Is the final temperature lower or higher? Why? 2- Is there a change in reaction enthalpy? Explain. 3- Is there any change in specific heats?
Methane is a clean gaseous fuel used in chemical industries worldwide. 1000 kmol/hr of methane is combusted in a burner to provide heat. The combustion reaction is: CH4 + O2 à CO2 + H2O Air is used for combustion and it can be assumed to be composed of 20% oxygen and 80% nitrogen. Nitrogen is considered inert and does not undergo any oxidation reaction. The inlet pressure for all stream is atmospheric. Use a conversion reactor in VMGSim simulation package to simulate burner. Assume that the heat loss to surrounding is negligible (very well insulated burner). Pressure drop across the burner is assumed to be 10 kPa. Assume adiabatic conditions with methane conversion of 95%. Follow the simulation guideline (to be provided) and having converged the simulation, export the results to WORD. The followings can be easily determined from the results: 1- Properties of exhaust gases such as average specific heat, enthalpy, entropy, thermal conductivity, viscosity etc. 2- Composition of exhaust gases from the burner in mole% and mass% 3- The flow rate of each component in the exhaust gas in Kg/h 4- Temperature of exhaust gases 5- Pressure of exhaust gases 6- Volumetric flow rate of gases Now repeat the simulation assuming the you use 50% excess air. You need to increase the mole fraction in the inlet stream to burner. Keeping all other conditions the same, compare the results of the two simulation and answer the following questions in the report. You may add these to the report (exported to WORD). 1- Is the final temperature lower or higher? Why? 2- Is there a change in reaction enthalpy? Explain. 3- Is there any change in specific heats?
Methane is a clean gaseous fuel used in chemical industries worldwide. 1000 kmol/hr of methane is combusted in a burner to provide heat. The combustion reaction is: CH4 + O2 à CO2 + H2O Air is used for combustion and it can be assumed to be composed of 20% oxygen and 80% nitrogen. Nitrogen is considered inert and does not undergo any oxidation reaction. The inlet pressure for all stream is atmospheric. Use a conversion reactor in VMGSim simulation package to simulate burner. Assume that the heat loss to surrounding is negligible (very well insulated burner). Pressure drop across the burner is assumed to be 10 kPa. Assume adiabatic conditions with methane conversion of 95%. Follow the simulation guideline (to be provided) and having converged the simulation, export the results to WORD. The followings can be easily determined from the results: 1- Properties of exhaust gases such as average specific heat, enthalpy, entropy, thermal conductivity, viscosity etc. 2- Composition of exhaust gases from the burner in mole% and mass% 3- The flow rate of each component in the exhaust gas in Kg/h 4- Temperature of exhaust gases 5- Pressure of exhaust gases 6- Volumetric flow rate of gases Now repeat the simulation assuming the you use 50% excess air. You need to increase the mole fraction in the inlet stream to burner. Keeping all other conditions the same, compare the results of the two simulation and answer the following questions in the report. You may add these to the report (exported to WORD). 1- Is the final temperature lower or higher? Why? 2- Is there a change in reaction enthalpy? Explain. 3- Is there any change in specific heats?
Explanation / Answer
Yes, there is a change in the number of moles of air supplied varies.
The temperature is higher as there is a relation between no of moles and temperature.
Q=dH products-dH of reactants-heat of reaction.
dH of products and reactants are a strong function of cp and the no of moles.
dH of reactants=sum of reactants enthalpy=no of moles * enthalpy of each species entering
dH of products=sum of products enthalpy=no of moles * enthalpy of each species leaving
There is change in all the three variables as the excess air used changes.