Methanol can be produced industrially by reacting carbon monoxide with hydrogen
ID: 1063572 • Letter: M
Question
Methanol can be produced industrially by reacting carbon monoxide with hydrogen in the following gas phase reaction: CO (g) + 2 H_2 (g) hArr CH_3OH (g) The reaction is an exothermic, equilibrium reaction and equilibrium conversion is favored at low temperatures. A methanol reactor is fed a stoichiometric mixture of CO and H_2. The reactants are fed at 200degree C and 20 bar pressure. Heat is removed from the reactor so that the product stream leaves at 250degree C. Under these conditions, the conversion of CO is 25%. Assume a basis of 100 kmol/hr of CO fed to the reactor. Calculate the molar flow rate of each of the species leaving the reactor. Calculate the rate at which heat must be removed from the reactor. Give your answer in kJ/hr. Use the heat of formation method to calculate your enthalpies. Use an enthalpy table to organize your calculations.Explanation / Answer
a)
Molar flow rate of CO = 100 kmol/hr
Molar flow rate of H2 = 200 kmol/hr
Conversion is 25%
So,
Molar flow rate of CH3OH = 0.25 x 100 = 25 kmol/hr
Molar flow rate of H2 = (1-0.25) x 200 = 150 kmol/hr
Molar flow rate of CO = (1-0.25) x 100 == 75 kmol/hr
(b)
Cp value of CO =29.12 kJ/kmol K
Cp value of H2= 28.614 kJ/kmol K
Cp value of CH3OH = 52.29 kJ/kmol K
Q = Products enthalpy - reactants enthalpy
= 25 kmol/hr x 52.29 kJ/kmol K x ( 523-298) + 75 kmol/hr x 29.12 kJ/kmol K x ( 523-298) +150 kmol/hr x 28.614 kJ/kmol K x ( 523-298) - ( 100 kmol/hr x 29.12 kJ/kmol K x ( 473-298) +200 kmol/hr x 28.614 kJ/kmol K x ( 473-298)
= 240.165 kJ/hr