GASEOUS FUELS 1.) Calculate the orsat analysis of the products of combustion upon burning pure hexane with 38% air if: a.)-Combustion is complete. Answer: 10.18% CO2 ; 6.13% O2 b.)- 85% of the C burns to CO2, the rest to CO, molal m: of H2 to CO is 1:2. Answer: 8.49% CO2; 1.5% CO 2.) The synthesis of methane enriched gas from water gas is a promising solution to the problem of hydrocarbon shortages in the future. In one such process, the following gas composition is obtained: 34% methane, 3% CO2, 11% CO,39% H2 and 13% N2. Determine the gross calorific value and net calorific value of gas in: a.)- MJ/ kgmol Ans: GCV: 445.62 NCV: 398.5 b.)- kcal/kgmol 106.43 106.43 c.)- MJ/ dSCM 18.8 16.82 d.)- MJ/ SCM 18.48 16.53 3.) Synthetic Natural Gas (SNG from a US based plant) has the molar composition: 96.59% CH4, 1.2% H2, 0.22% CO and 1.9% CO2. Calculate the GCV and NCV in: a.)- MJ/ kgmol Ans: GCV: 864.88 NCV: 779.24 b.)- kcal/gmol 206.56 186.11 c.)- kcal/kg 12612.19 11363.55 d.)- kcal/ SCM 8566.04 4.) A fuel containing 75% ethane and 25% propane is burned with dry air. All the H2 burns to H2O and the CO2 to CO ratio is 10.1. Fifteen percent excess air supplied. Calculate: A.) Moles stack gas/100 moles fuel (22.95) B.) Orsat analysis of stack gas (10.38% CO2, 1.04% CO) C.) Complete analysis of stack gas (8.91 CO2, 0.89% CO) D.) m3 dry air at 28 oC, 765 mm Hg/kgmole fuel (520.66) 5.) 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, 745 torrs and 90% RH is burned in wet water 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 ration of CO2 to CO 1:8; H2 to CO is 1:4 Ans.: 11.56% CO2, 1.44% CO B.) m3 air/m3 BWG (Ans. 2.88) C.) m3 stack gas (100 kPa: 300oC)/ 100 moles dry BWG ANS.: 17036.81 D.) GCV of BWG (MJ/kgmol) Ans.: 263.39 E.) % Calorific Value lost due to i) CO (5.55) ii) H2 (1.4) iii) H2O (8.24) iv) Sensible heat (12) F.) Thermal Energy (72.9%) 6.) Carburetted water gas is produced in the same way as blue water gas except that 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 (183%) b.) Orsat analysis of the stack gas (400oC, 760 torrs) if 85% of C burns to CO2: all H2, burns to H2O ANS.: 5.33% CO2 , 0.94% CO c.) GCV in MJ/kgmol (391.68) d.) % calorific value lost due to i) CO (6.984) ii) Uncondensed water vapor (7.79) iii) Sensible heat (33.66) 7.) Bottled Gas (Liquefied Petroleum Gas) is found to certain 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 % methane, 1.2% propane, 0.9% n-butane and 4.7% i-butane is available at P 2.50/ SCM. A fuel is to be slected between the two for curing a refractory lined furnace. Which is cheaper? ANS.: ASSOCIATED GAS 8.) A pure saturated hydrocarbon is burnt with excess air. Orsat analysis of the stack gas shows 7.9% CO2 1.18% CO, 0.24% H2 5.25% O2 and 85.93%N2. Air is substantially dry. The stack gases leave at 750 mm Hg pressure. Calculate: A.) % excess air (24.986%) B.) kg air/ kg fuel (21.58) C.) Formula of the hydrocarbon (CH4) D.) Dew point of the stack gas (54.29 oC)
9.) Bottled gas 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 (35.02) B.) Composition of the bottled gas (55.17% propane) 10.) 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 (29.97%) B.) Complete orsat analysis of stack gas (5.2% O2, 84.88% N2) C.) Dew point of stack gas (50.86 oC) 11.) Producer gas analyzing 25.3% CO, 13.2% H2 , 0.4% CH4, 5.4% CO2 , 0.5% O2 and 55.2% N2 is burnt in excess air at 25 oC, 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 (11.04) B.) Complete orsat analysis of the stack gas (2.50% O2; 78.86% N2 ) C.) GCV (112.96 MJ/ kgmol) D.) % Calorific value lost due to CO and H2 (7.77 ; 3.164) 12.) 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 30 oC,, 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 (15%) B.) Formula of the hydrocarbon (CH4) C.) Complete orsat analysis of the stack gas (3.65% O2 ; 86.37% N2.) 13.) A mixture of a saturated hydrocarbon and N2 is burned in excess air supplied at 25o C, 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 53.46 oC. The stack gases leave at 300 oC, 765 mm Hg with a volume ratio of 2.049 m3 wet stack/gas m3 wet air. Calculate: A.) Formula of the hydrocarbon (C2H6) B.) Volume % analysis of the fuel (74.72% C2H6 ) C.) % excess air (24.985) LIQUID FUELS 1.) Crude petroleum oil is generally considered to be formed from animal and vegetable debris accumulating in sea basins or estuaries and decomposed by anaerobic bacteria resulting in a black viscous product. A typical elemental analysis shows 80% C, 13% H, 1% N, 3% O and 3% S. During a certain combustion, air supplied is less than the theoretical so that all of the O2 is used up, 70% of the C burns to CO2, the rest to CO: the molal ratio of CO to H2 in the exhaust gas is 1:2. Calculate: A.) ORSAT analysis of the exhaust gas (12.56% CO2, 5.38%% CO) B.) % of the theoretical air which is supplied for combustion (70.7%) 2.) An alcogas mixture made up of 85% gasoline (octane no. = 95) and 15% ethanol is used as fuel for an engine in the presence of 17.05 m3 air/kg alcogas supplied essentially dry at 30o C and 740 mm Hg. 80% of the C burns to CO2, the rest to CO: molal ratio of H2 to CO is 1:2. Calculate: A.) Orsat analysis of the exhaust gas (8.18% CO2 , 2.04% CO, 1.02% H2 ) B.) % excess air (36.143%) 3.) A ternary blend of gasoline (90% octane no.), alcohol (75% ethanol, 25% methanol) and benzole (75% benzene, 15% toluene and 10% xylene) is burned completely in 35% excess O2 . Analysis of the blend shows 70% gasoline, 15% benzole and 15% alcohol. Calculate the complete analysis of the exhaust gas. (9,77% CO2, 5.15% O2, 74.68% N2, 10.41% H2O) 4.) A boiler uses a high grade distillate fuel oil with a calorific value of 43.38% MJ/kg. Analysis of the stack gases at 375o C and 765 torrs shows 9% CO2, 1.21% CO, 0.37% H2 , 7.05% O2 and 82.37% N2. Assuming that the fuel oil consists only of hydrocarbons. Calculate: A.) % excess air (40.03%) B.) Wt % composition of the fuel oil (84.95% C, 15.05% H) C.) % CV lost due to: i.)Unburnt combustible (7.17%) ii.)Uncondensed water (7.38%) iii.) Sensible heat (19.51%) 5.) A furnace is fired with fuel oil with partial analysis of 7.6% S and 2.8% N. Orsat analysis of the stack gas shows 9.44% CO2 , 1.19% CO, 0.4% SO2 , 0.47% H2 , 6.8% O2 and 81.7% N2 , Air supplied is at 23o C , 755 mm hg and 85% RH. Calculate: A.) % Excess air (38.03%) B.) Analysis of the fuel oil (75.74% C; 11.4% H; 2.46% O) C.) m3 air/kg fuel (15.34)
6.) Coal tar fuels are liquid fuels obtained by blending coal tar distillation products such as carbolic oil, naphthalene oi, creosote oil, anthracene oil and medium pitch. A sample elemental analysis shows 85.9% C, 6.3% H, 1.2% S 5.5% O and 1.1% N. If this fuel is burned in excess air at 30o C and 755 mm Hg with 90% RH, it produces a burner gas containing 10.64% CO2 , 3.19% CO and 0.64% H2 . Calculate: A.) % excess air (27.18%) B.) Complete orsat analysis (6.41% O2 , 79.15% N2) C.) m3 stack gas/kg coal tar (22.03) 7.) The principal motor fuel blend in Germany has been Reichkraftskoff made up of 50% motor benzole (75% benzene; 15% toluene, 10% xylene), 25% tetralin (C10H12) and 25% industrial alcohol (80% ethanol, 20% methanol). After combustion in excess air, a stack gas containing 9.13% CO2 and 1.83 H2 is obtained. Calculate A.) % excess air (50%) B.) complete analysis of the stack gas (8.09% O ; 80.95% N) SOLID FUELS 1.) A sample lignite was found to contain 34.55% moisture, 22.91% FC, 7.2% ash, 1,1% S and ).57% N with calorific value of 16.45 MJ/jg. Calculate: A.) Proximate Analysis (35.43% VCM) B.) Modified Analysis (46.147% C, 52% NH, 9.913% CW) C.) Ultimate Analysis (5.46% H; 39.52% O) D.) Analysis of VCM (65.76% C; 1.47% NH, 28.05% CW) E.) Calorific value of VCM (24.63% MJ/kg) 2.) A burner uses Pittsburgh coal analyzing 14.1% ash, 2.1% N and 4.3% S. Excess air supplied dry at 22O C and 1 at,. The stack gases at 285O C , 765 mm Hg analyzes 9.65% CO2, 1.16CO, 0.24% SO2, 0.58% H2 and 9.16% O2 Calculate: A.) % excess air (65.12%) B.) Complete ultimate analysis (72.63% C; 4.11% H, 2.76% O) C.) m3 air/ kg coal (13.56) 3 D.) m SG/kg coal (26.25) 3.) On an as received basis, the proximate analysis of a representative coal from the Semirara Plant is 32% VCM, 53% FC, 10% ash, 1.2% N and 6.2% S. Its calorific value is 23.78 MJ/kg . On the assumption that this coal is burnt with 150% excess air so that the molal ration of CO2 to CO is 5:1, calculate: A.) m3 dry air at 25 degrees Celsius , 750 mm Hg/kg coal (16.64) B.) Complete analysis of the fuel gas ( 5.76 % CO2 , 1.15% CO, 0.28% SO2 ; 12.75% O2; 76.41% N; 3.66% H2C) C.) m3 fuel gas at 240 degrees Celsius , 770 mm Hg/kg (28.87) D.) % CV lost due to: i)Unburnt combustibles (9.52%) ii) Uncondensed water (4.71%) iii) Sensible heat (19.24%) 4.) A boiler is fired with coal containing 72.63% C; 1.4% ash; 1.6% N and 1.2% S burnt under conditions that the elimination of the combustibles from the refuse is complete. The air enters the furnace at 25 degrees Celsius , 760 mm Hg with 80% RH. The flue gases goes to the stack at 280 degrees Celsius and 110 kPa. The average flue gas orsat analysis is 8.41% CO2 ; 2.52 % CO; 0.76% H2 and 9.86% O2. Calculate the following: A.) % excess air (65.08%) B.) Ultimate analysis of coal (4.535 H ; 6.04% O) C.) m3 flue gas/kg coal (24.5) D.) m3 air/kg coa (13.79) 5.) A certain coal is pulverized and burnt in burner. Analysis of coal showed 70% C; 10.7% ash and 1.2% N. The refuse is substantially free of combustible. A sample of the flue gas collected and analyzed in an orsat apparatus over mercury contains 8.3% CO2 , 3.32% CO, 0.32% SO2 ; 3.32% H2 ; 9.53% O2; Calculate: A.) % excess O2 (45.13%) B.) Complete ultimate analysis of coal (4.68% H; 8.28% O; 5.14% S) C.) m3 flue gas (250 degrees Celsius; 1 atm)/kg coal (22.72) 6.) A high volatile B bituminous coal analyzing 22% VCM, 64% FC, 4% M, 1.4%N and 1.6 % S has a calorific value of 32.5 MJ/kg. It is burned in excess air supplied essentially dry at 28 degrees Celsius and 1 atm. The stack gases leave at 250 degrees C , 740 mm Hg and contain 8.37% CO2 ; 4.19% CO and 2.51% H2 . Calculate: A.) % excess O2 (40%) B.) Complete orsat analysis of the stack gas ( 9.11% O2 ; 75.82% N2) C.) m3 stack gas/ m3 air (1.89) SOLID FUELS 1.) A furnace is fired with coal with the following proximate analysis: 5% M, 60% FC, 25% VCM and 10% ash. Its calorific value is 31.33 MJ/kg . Calculate the % VCM lost, % C lost and % CV lost in the refuse if the refuse analyzes: A.) 25% FC, 4% VCM, 71% ash (5.1, 4.59, 2.25) B.) 14.4% FC, 6% VCM, 79.6% ash (3.02) C.) 19.6% C, 80.4 % ash (3.2; 2.63)
2.) A high volatile A bituminous coal analyzing 73.77% C, 5.23% H, 10% O, 1.4% N, 8.1% ash, 3.9% M and 1.5% S is burned in a furnace together with 45% excess air supplied saturated at 25 degrees Celsius and 1 atm. Analysis of the wetted refuse shows 16% VCM, 23.55% FC, 32.48% ash and 27.97% H2O . The stack gases leave at 300 degrees C , 745 torrs with a CO to CO2 ratio of 0.12 Calculate: A.) % C and CV lost in the refuse (11.18) B.) Type of combustible in the refuse (Uncoked coal) C.) Orsat analysis of stack gas (10% CO2; 1.2% CO) D.) m3 SG/kg coal (25.25) E.) % CV lost due to CO and Sensible heat (5.38, 14.76) 3.) The following data were obtained during coal combustion: COAL: 13.8% VCM, 74.6% FC, 8.6% ash, 3% M, 0% N, 1.2% S CV: 32.9582 MJ/kg Refuse: 4% VCM, 40% FC, 56% ash: Air 25 degrees C ; 740 torrs, 80% RH; 50% excess O2 Stack gas: 300 C, 755 torrs, H2/Co ratio= 1:4 CO/CO2 ratio= 1:10 Calculate: A.) m3 air kg/coal (14.19) B.) Orsat analysis of the stack gas (10.39% CO2 ; 1.04% CO, 0.26% H2) 4.) Coal fired in a furnace analyzes 16.6% VCM, 16% ash 61.4% FC, 6% M, 1.2% N and 1.8% S with a calorific value of 26.75 MJ/kg. Analysis of the refuse shows 44% ash, 8% VCM, 34% FC and 14% H2O . Partial orsat analysis of the stack gas shows 10.77% CO2 , 1.62% CO and 0.81% H2. Air supplied is at 27 degrees C , 765 torrs with 80% RH. Calculate: A.) % C and % VCM lost in the refuse (19.92 ; 17.52) B.) % excess O2 (20.4) C.) m3 air/kg coal (9.035) D.) Orsat Analysis of the stack gas (8.17% O2 ; 78.63% N2) 5.) A high grade semi-anthracite coal has complete analysis of 85.86% C, 4.44% H, 2.7% O, 1.2% N, 5% ash and 0.8% S. Analysis of the refuse shows 58% C and 42% ash. Air is supplied dry at 30 degrees Celsius and 750 mm Hg. Partial orsat analysis of the stack gas (200 degrees C ; 755 mm Hg) shows 8.05% CO2 ; 2.42% CO and 2.9% H2. Calculate: A.) % excess O2 (55) B.) Complete orsat analysis of stack gas (10.73% O2 75.9% N2) C.) m3 stack gas/ m3 air (1.624) 6.) A sample of coal was found to contain 1%N 10% ash and 5.8% S. Analysis of the refuse showed uncoked coal with 20.71% VCM lost in the refuse. Orsat analysis of the stack gas shows 8.93% CO2 1.56 CO 0.34% SO2 9.87% O2 and 79.29% N2. -Calculate: A.) Complete ultimate analysis of coal (67.1% C; 3.95% H; 12.15%O) B.) Complete analysis of the refuse if contains 37.93 % ash (54.3% FC; 7.77% VCM) C.) % excess O2 (39.50%) 7.) Coal fired in a furnace analyzes 57.1% C 8% ash , 1.4% % N and 0.77% S. The refuse contains 24.5% and 75.5% ash. Orsat analysis of the stack gas shows 11.21% CO2 1.57% CO 7.45% O2 and 79.77% N2. Calculate: A.) Complete ultimate analysis of coal (5.85% % H, 26.88% O) B.) % excess O2 (40%) 8.) Coal fired in a furnace analyzes 30% VCM, 51% FC, 14% ash, 5% M, 1.6% N and 1.2% S with a GCV of 30.1 MJ/kg. Refuse analysis shows 30% FC 15% VCM 40%ash and 15% H2O .Air supplied is saturated at 25o C ; 740 mm Hg. Molal ratio of CO2 to CO is 5:1 and H2 to CO is 1:1. The stack gas leaves at 300 degrees C and 765 mm Hg. Calculate: A.) Orsat analysis of the stack gas (7.97% CO2 ; 1.59% CO, 1.59 H2 ; 11.15% O2 ; 77.69% N2) 3 3 B.) m stack gas/ m air (1.96) SULFUR AND ITS COMPUNDS
1.) Raw sulfur which is 75% pure is burned in excess air supplied at the rate 4.713m3 /kg of raw sulfur at 25 degrees C. 745 mm Hg with 80% RH. If 87% of the sulfur charged burn to SO2 and the rest to SO3 Calculate: A.) % excess air (S to SO2) (65%) B.) % excess air (S to SO3) (10%) C.) Complete analysis of the burner gas (10.88% SO2 ; 7.32% O2 ; 77.62% N2 ; 1.63% SO3 ; 2.56% H2O) 2.) The burner gas from a sulfur burner analyzes 9.2% SO2 7.13 O2 and 83.7% N2. The raw sulfur charged contains 82% pure sulfur and analysis of the the cinder shows 20% unburned sulfur. Calculate: A.) % excess air (S to SO2) (60%) B.) % excess air (S to SO3) (6.67%) C.) m3 of saturated air (28 degrees C; 750 torrs)/kg raw S (5.076) 3 D.) m of burner gas (300 degrees C; 730 torrs)/kg raw S (9.75) 3.)Pyrite analyzing 78%FeS2 and 22% gangue is burned at the rate of 1000 kg/hr . Analysis of the cinder show 7.22% S as unburned FeS2 and SO3 absorbed by Fe2O3 .Air supplied is 70% in excess based on the conversion of Fe2O2 to SO2 . The ratio of SO2 to SO3 in the burner is 3.48:1. Calculate: A.) % excess air (FeS2 to SO3 ) (24.67%) B.) % of theFeS2 charged lost in the cinder (12%) C.) Complete analysis of the burner gas (6.26% SO2 ; 9.57% O2 ; 82.35% N2 1.82% SO3)
4.) In the burning of pyrite containing 92% FeS2 and 8% gangue, 13% of the FeS2 charged is lost in the cinder. A partial analysis of the cinder also shows 5.31% SO3. The orsat analysis of the burner gases shows 6.75% SO2 6.88% O2 and 86.38% N2 . Air supplied is at 23 degrees Celsius; 743 mm Hg and 88% RH. Calculate: A.) % excess air ( FeS2 to SO2) (40%) B.) % excess air ( FeS2 to SO2) (2.676%) C.) m3 air.kg pyrite (3.58) D.) m3 burner gas (250 degrees C 750 mm Hg)/kg pyrite (5.926) 5.) Raw sulfur containing 83% pure S is burned together with 80% excess air (S to SO2). An analysis of the cinder shows 20% unburned sulfur and 80% inerts. Air is supplied saturated at 30 degrees C and 750 mm Hg. The gases from the burner enter a converter gas analyzing 0.55% SO2 11.99% O2 and 87.46% N2 . Calculate per 100 kg raw sulfur: A.) Complete analysis of the burner gas (9.56% SO2 9.03% O2 76.07 % N2 1.07% SO3 4.25% H2O) B.) % of sulfur dioxide entering the converter that is converted to SO3 (88.3%) C.) Weight of a 60% dilute H2SO4 needed to produce an 87% H2SO4 (284.04) D.) If the absorbing acid is 94% H2SO4 what weight of a 14% oleum is formed (587.61) 6.) Pyrite containing 80% FeS2 and 20% gangue is burned in excess air to produce a gas with a complete analysis of 7.78% SO2 1.39% O2 82.06% N2 4.92%% SO3 and 3.85% H2O. Analysis of the cinder shows that a total sulfur content of 6.46& due to the presence of unburned FeS2 and SO3 absorbed by Fe2O3 . Air supplied is at 27 degrees Celsius ; 745 mm Hg and saturated with vapor. The burner gases then enter a converter together with 30% excess secondary air (supplied at the same conditions as primary air) based on the complete conversion of all SO2 to SO3 75% of the SO2 actually burns to SO3 . The converter gases enter an absorber and absorbed in acid solution. The waste gases formed has a partial orsat analysis of 0.7% SO2 . Calculate per kg of pyrite: A.) % excess air (S to SO2) (10.17) B.) Complete analysis of the converter gas (1.79% SO2 1.58% O2 83.77% N2 9.55% SO3 3.42% H2O) C.) kg of an 80% H2SO4 formed from 40% acid charged (1.84) D.) kg of a 75% H2SO4 needed to produce 10% oleum (0.662) 7.) The burning of raw S consisting of 95% S and 5% inerts produces a gas whose orsat analysis 11.39% SO2 7.76% O2 and 80.84% N2 10% of the total sulfur charged is lost in the cinder. The burner gases are cooled and absorbed in milk of lime is obtained by slaking a lime consisting of 58% CaO 32% MgO and 10% inerts with water. The bisulfite liquor formed contains 12% SO2 of which 2% is free and the rest present as bisulfites. Orsat analysis of the waste gas shows that it contains 7.39% O2 and 92.61% N2 Calculate: A.) Kg bisulfite liquor /kg raw sulfur (9.65) B.) Kg lime consumed/ kg raw sulfur (0.8832) C.) Kg of water used for slaking/ kg raw sulfur (6.92) 8.) The roasting of pyrites analyzing 85% FeS2 and 15% gangue utilizes 40% excess air (FeS2 to SO2) supplied at the rate of 358 cubic meter/ hour at 23 degrees C; 743 mm Hg and 86% RH. A partial analysis of the cinder showed 25.92% FeS2 and 17.83% gangue. Only 65% of the FeS2 gasified is converted to SO2 and the rest to SO3 . The burner gases are cooled and charged to a converter together with a slaked lime from dolomitic lime containing 75% CaO, 25% MgO. If 850 kg/hr of bisulfite liquor are produced with no oxidation of SO2 to SO3 taking place. Assume all SO2 converted to bisulfite. Calculate: A.) kg/hr of lime (33.724) B.) kg/hr of water for slaking (704.77) C.) Complete analysis of the burner gas (5.35% SO2 8.36% O2 81.06% N2 2.15% SO3 and 2.61 H2O)
