QUESTION 2 A polluted waste air stream at 93.3degC is combusted in a thermal oxidiser operating at 648.9 deg C using dry natural gas at 15.6 deg C. The average gas velocity of the waste air stream and combustion products within the oxidiser is 6.1m/s. Calculate the flowrate of natural gas required, given the following additional information: 0.3 Table 1: Natural gas composition Gross heating value of natural gas =41169kJ/m3 Volumetric flowrate of polluted air= 8500m3/h (@15.6 deg C, 1atm ) Length/diameter =2 2 Table 2: Enthalpy of combustion gases ( kJ/kgmol )