Question

3. (20) Fire Heater Specification After the reactor feed leaves the heat exchanger, it enters a fire heater. In this unit the stream is further heated from 215°C to 350°C, which requires 4649 kJ/h of heat to be added. To accomplish this, the heat from the combustion of methane gas is used: CH4(2) +2 02(g) → CO2() + 2 H20(2) $ = 10.0 molh The design of this fire heater indicates that the temperature of the flue gas will not be higher than 1100°C. Determine whether or not the design is correct. For simplicity, you may assume that the following heat capacity values are constant within the range 0° to 1200°C: Cp [CH4(g)] = 0.060 kJ/mol °C Cp [O2(g)] = 0.033 kJ/mol °C Cp [N2(g)] = 0.031 kJ/mol °C Cp [CO2(g)] = 0.050 kJ/mol °C Cp [H2O(g)] = 0.032 kJ/mol °C Gas Reactor Feed @ 215°C Gas Reactor Feed @ 350°C Methane + Air T= 25°C 10.0 mol CH (g) 20.0 mol O2(g/h 75.2 mol N2(g) Fire Heater T = 232 10.0 mol CO2(g) 20.0 mol H2O(g)/h 75.2 mol N2(g) Flue Gas

Answer 1

sof lomd (Hy 20ml Or 75-2 md No lomo cas Jomoh Foogme Na T. Q = 4649 kJ/h on 4649 Apply Energy Energy Belonie system: (Energy in ) -(Energy out) - Consumption) -o Gen) so Ź nr (pilt: -85- Žn. Cp (T-05) 50-0. Toxlo-os) (T-05) + 30*0.039*(T-95)+ 75-ax0º031 (T-5) # 3-4712 (7-15)#4649 T-25=4649 3-4719 T-1364.3°C So design Cleody Outlet Temp 71100°C not correct. is

using given data and energy balance we can find the required Temperature at gas outlet

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