QUESTION 4 A stream of pure propane (C3H₁) and a stream of pure butane (C4H₁0) are both fed to a continuous combustion c

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Question 4 A Stream Of Pure Propane C3h And A Stream Of Pure Butane C4h 0 Are Both Fed To A Continuous Combustion C 1 (71.91 KiB) Viewed 27 times

QUESTION 4 A stream of pure propane (C3H₁) and a stream of pure butane (C4H₁0) are both fed to a continuous combustion chamber, where they are burned with pure oxygen. Gas analysis indicates that the product gas from the combustion chamber contains 47.4 mole% H₂O. The combustion gases are then fed to a condenser, where all of the water vapour is removed (as condensate) to give a gas stream containing 69.4 mole% CO₂ and the balance is O2. (a) Write down the two combustion reactions occurring in this process (i.e. separate combustion reactions for propane and butane), assuming that there is complete oxidation of the hydrocarbons and that the only reaction products are carbon dioxide and water. [10%] (b) Prepare a carefully labelled PFD, indicating mole fractions and molar flows (both known and unknown) for all process streams. [10%] (c) Perform a Degrees of Freedom analysis for (i) the overall process, and for the sub- systems associated with (ii) the combustion chamber and (iii) the condenser. Show that, if a basis of 100 mol/min of dry product gas is assumed, the system can be balanced. [20%] (d) [30%] [20%] Determine all unknown molar flows and compositions (i.e. mole fractions). (e) Express the composition and flow rate of the dry product gas in mass units. (f) What would the composition of the gas from the condenser be, if combustion took place under stoichiometric oxygen conditions? (No calculations are required.) [10%] O UCD 2016/2017 Page 3 of 4