Jul 01, 2019 Steam power plant Steam Generator or Steam Boiler - is an integrated assembly of several essential components the function of which is to produce steam at a predetermined pressure and temperature. Classification of Boilers: 1. Water tube boiler - a steam boiler in which water circulates within tubes and heat is applied from outside the tubes to generate steam. 2. Fire tube boiler - is a steam boiler in which hot gaseous product of combustion pass through tubes surrounded by boiler water. 1 Jul 01, 2019 Performance of steam generator (boiler) 1. heat supplied by fuel, Qs - it is the heat generated by the fuel. where: mf = mass of fuel Qh = higher heating value of fuel 2. boiler heating surface, HS m2 - it is the total area in through which the heated water and hot gases exchange heat. where: A1 = area of shell A2 = inside area of all tubes A3 = area of the rear head A4 = cross-sectional area of the tube section D = diameter of shell di = inside diameter of tube do = outside diameter of the tube t = wall thickness of tube L = length of tube n = no. of tubes 2 Jul 01, 2019 What is the boiler heating surface of a fire-tube boiler operating at 200 psia (1.378 MPa) with 200 oF (93.3oC) feedwater, both at saturated condition. The diameter of the boiler is 213.4 cm, length of 5.5m, and having 84 tubes, 10.2 cm inside diameter, 10.5 cm outside diameter. A. 148.14 m2 C. 158.14 m2 B. 168.14 m2 D. 178.14m2 3. rated boiler horsepower - it is the Manufacturer's rating equivalent to the heating surface in m2 divided by 0.91 for water tube and 1.1 for fire tube. a. for water tube boiler: b. for fire tube boiler: 3 Jul 01, 2019 What is the heating surface area of a water tube boiler if the equivalent rated boiler horsepower is 200? A. 182 C. 450 B. 206 D. 198 The heating surface area of a fire tube boiler is 400 m2. What is the equivalent rated boiler horsepower? A. 363.63 Hp C. 256.78 Hp B. 435.72 Hp D. 135.72 Hp 4 Jul 01, 2019 4. developed boiler horsepower - it is the actual heat absorption divided by 35,322. note: 1 bo.Hp = 35,322kJ/hr where: ms = mass of steam in kg/hr hs = enthalpy of steam in kJ/kg hf = enthalpy of feedwater in kJ/kg 5. percent rating - it is the ratio of the developed boiler horsepower to the rated boiler horsepower. 5 Jul 01, 2019 What is the percent rating of a water tube boiler if the heating surface area is 400 m2 and the developed boiler horsepower is 750. A. 170.625% C. 130.625% B. 140.675% D. 120.765% 6. ASME evaporation units - it is the heat output of the boiler or the rate at which heat is transformed. 7. factor of evaporation, FE - it is the actual heat absorption per kg of steam generated divided by 2257 (hfg from and at 100 oC). 6 Jul 01, 2019 What is the developed boiler horsepower if the steam rate is 0.86 kg/s and the factor of evaporation is 1.25. A. 244.41 hp C. 200.57 hp B. 214.54 hp D. 157.25 hp 8. equivalent evaporation, EE - it is the product of the rate of evaporation of steam and factor of evaporation. 9. actual specific evaporation or boiler economy, ASE - it is the ratio of the mass of steam to the mass of fuel. 7 Jul 01, 2019 10. equivalent specific evaporation, ESE - it is the product of the actual specific evaporation and the factor of evaporation. 11. boiler efficiency or overall thermal efficiency, ebo - is the measure of ability of a boiler or steam generator to transfer the heat given it by the furnace to the water and steam. - if there is no reheater and no boiler blowdown: where: ms = amount of steam mrs = amount of reheated steam mbo = amount of water blowdown at boiler pressure hs = enthalpy of steam hf = enthalpy of feedwater hro = enthalpy of the steam leaving the reheater hri = enthalpy of the steam entering the reheater hbo = enthalpy of saturated liquid at boiler pressure 8 Jul 01, 2019 The heating value of fuel supplied in a boiler is 40,000 kJ/kg. If the factor of evaporation is 1.10 and the actual specific evaporation is 10, what is the efficiency of the boiler? A. 62.07% C. 78.05% B. 53.08% D. 54.97% What would be the percentage of the over-all efficiency of a steam generator obtaining an evaporation equivalent to 10.95 kg of water from and at 100 oC per kg of coal containing 34,064 kJ/kg heating value? (@100oC; hs = 2676.1 kJ/kg, hf = 419.04 kJ/kg). A. 73% C. 82% B. 74% D. 70% 9 Jul 01, 2019 Coal with a higher heating value of 6700 kCal/kg is consumed at the rate of 600 kg/hr in a steam generator with a rated boiler horsepower of 200. The feedwater temperature is 82oC and steam generated is at 10.2 kg/cm2 abs. saturated condition. The horsepower developed is equivalent to 305. @10.2 kg/cm2; hs=2778.1 kJ/kg @ 82 oC; hf = 343.3kJ/kg Coal with a higher heating value of 6700 kCal/kg is consumed at the rate of 600 kg/hr in a steam generator with a rated boiler horsepower of 200. The feedwater temperature is 82oC and steam generated is at 10.2 kg/cm2 abs. saturated condition. The horsepower developed is equivalent to 305. @10.2 kg/cm2; hs=2778.1 kJ/kg @ 82 oC; hf = 343.3kJ/kg a. What is the heating surface area, H.S? b. rate of steam, ms c. percent rating d. ASME evaporation unit e. factor of evaporation, FE f. overall thermal efficiency, ebo g. actual specific evaporation, ASE h. equivalent specific evaporation, ESE 10 Jul 01, 2019 12. net boiler efficiency, ebo. net - it is the boiler efficiency less the energy consumed by accessories. What is the net boiler efficiency if the heat henerated by fuel is 40,000,000 kJ/hr and the boiler auxiliaries consumes 2MW. The ASME evaporation units of a boiler is 25,900,000 kJ/hr. A. 46.0% C. 46.25% B. 46.75% D. 47.0% 11 Jul 01, 2019 13. boiler and furnace efficiency, ebf where: mash = amount of ash refired Qash = heating value of ash 14. grate effieciency, egrate where: mc = amount of carbon in reuse or ash QL = heating value of combustibles in refuse or ash 12 Jul 01, 2019 SW: 30 items 10 pts 1. Two boilers has a capacities of 200 kg/hr and 250 kg/hr. If 150,000 kg of coal are supplied to two boilers, how many days to consume the available fuel? A. 24 days C. 15.87 days B. 17.87 days D. 13.89 days 20 pts 2. A steam generating unit receives feedwater at 5 MPa, 200 oC and delivers steam at 4.5 MPa, 320 oC at rate of 30,000 kg per hour. The main steam turbine has a steam rate of 6.5 kg/kw-hr of generator output. Auxiliaries used steam as follows: forced-draft fan .........................25kw induced-draft fan ......................40 kw soot blower ..............................3300 kg/day if fuel with a higher heating value of 40,000 kJ/kg as fired is consumed at the rate of 1890 kg per hour, account for the steam generator net efficiency. steam properties: @4.5 Mpa, 320oC @5.0Mpa,200oC h = 3000.6 kJ/kg h = 853.9 kJ/kg A. 86.3 C. 83.6 B. 81.24 D. 82.41 13
