PROBLEM SETin ChE CALCULATIONS 2 Submitted by: Princess Janine B. Catral (Student) Submitted to: Engr. Ma. Haidee Mabborang (Instructor) 1. Blue Water Gas is obtained by passing steam over red hot carbon enriched coal (coke). The gas is called “Blue” water gas because of its blue flame, a characteristic of the combustion of CO. A typical composition shows 4.7% CO2, 41% CO, 49% H2, 0.8% CH4 and 4.5% N2. If blue water gas at 25oC and 745 torrs and 90% RH is burned in wet air, 30% in excess, supplied at the same conditions as BWG with 85% RH, calculate: a. Orsat analysis of the stack gas if the molar ratio of CO2 to CO 1:8, H2 to CO is 1:4 b. m3 air/ m3 BWG c. m3 stack gas (100 kPa; 300oC)/ 100 moles dry BWG d. GCV of BWG (MJ/kgmol) e. % Calorific Value lost due to (i) CO, (ii) H2, (iii) H2O, (iv) Sensible Heat f. Thermal efficiency 2. Carburetted water gas is produced in the same way as blue water gas except that it is done in the presence of cracked oil vapors in a carburetor. A typical gas analysis shows 4.7% CO2, 7.8% C2H4, 0.3% O2, 36.5% H2, 35.5% CO, 8.6% CH4 and 6.6% N2. If this gas is saturated with H2O at 20oC, 742 torrs and burned in 10.434 m3 air at 30oC, 101 kPa and 60% RH per m3 fuel, calculate: a. % excess O2 b. Orsat analysis of the stack gas (400oC, 760 torrs) if 85% C burns to CO2; all H2 burns to H2O c. GCV in MJ/kgmol d. % calorific value lost due to: (i) CO, (ii) uncondensed water vapour, (iii) sensible heat 3. Bottled Gas (Liquefied Petroleum Gas) is found to contain 1.4% ethane, 23.8% propane, 20.7% i-butane, and 54.1% n-butane. It is available at P 15/kg. Associated gas analyzing 83.6% methane, 9.6% ethane, 1.2% propane, 0.9% n-butane and 4.7% i-butane is available at P2.50/SCM. A fuel is to be selected between the two for curing a refractory lined furnace. Which is cheaper? 4. A pure saturated hydrocarbon is burnt with excess air. Orsat analysis of the stack gas shows 7.9% CO 2, 1.18% CO, 0.24% H2, 5.25% O2, and 85.43% N2. Air is substantially dry. The stack gases leave at 750 mm Hg pressure. Calculate: a. % excess air b. kg air/kg fuel c. Formula of the hydrocarbon d. Dew point of the stack gas 5. Bottled gases are the liquefied petroleum gases propane and butane. If a sample of this gas were burned in excess air, a burner gas of the following analysis is obtained: 8.62% CO2, 1.38%CO, 6.45%O2 and 83.55% N2. Calculate: a. % excess air b. Composition of the bottled gas 6. The burning of pure ethane with dry air gives a stack gas which analyzes 9.92% CO2. The stack gases leave at 745 mm Hg. Assuming complete combustion, determine: a. %excess air b. Complete orsat analysis of stack gas c. Dew point of stack gas 7. Producer gas analyzing 2.3% CO, 13.2% H2, 0.4% CH4, 5.4% CO2, 0.5%O2, and 55.2% N2 is burned in excess air at 25oC, 745 torrs and 60% RH. Partial orsat analysis of the stack gas shows 16.13% CO2, 1.79% CO and 0.72% H2. Calculate: a. %excess O2 b. Complete orsat analysis of the stack gas c. GCV d. % Calorific value lost due to CO and H2 8. A pure saturated hydrocarbon is burned in excess air. Air is supplied at the rate of 284.14 m3/kgmol of the hydrocarbon. Air enters at 30oC, 1 atm and saturated with water vapor. Partial orsat analysis of the stack gas shows 8.68% CO2 and 1.3% CO. Calculate: a. % excess air b. Formula of the hydrocarbon c. Complete analysis of the stack gas 9. A mixture of a saturated hydrocarbon and N2 is burned in excess air supplied at 25oC, 740 torrs with 90% RH. An orsat analysis of the stack gas shows 7.6% CO2, 22.28% CO, 1.14% H2, 6.03% O2 and 82.95% N2 with a dew point of 53.46oC.The stack gases leave at 300oC, 765 mm Hg with a volume ratio of 2.049 m3 wet stack gas/m3 wet air. Calculate: a. Formula of hydrocarbon b. Vol % analysis of the fuel c. % excess air