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53Bureau of Energy Efficiency
1. What is the importance of draft in boilers?
2. What is a balanced draft system?
3. Which is the single major heat loss in boiler?
4. Explain the principle of modulating control in a boiler?
5. Explain the principle of fire tube and water tube boilers?
6. Explain the principles of fluidized bed combustion and pulverized fuel combustion?
7. Name three factors affecting the boiler efficiency and explain briefly?
8. Discuss the various types of draft in boiler system?
9. What do you understand by terminology fire tube and water tube in boiler?
10. Discuss the various types of heat losses in a boiler?
11. How do you measure boiler efficiency using direct method?
12. What do you understand by term evaporation ratio? What are the typical values for coal and oil-fired boiler?
13. What do you understand by the term ‘Turn Down Ratio’ ?
14. What are the methods available for assessing the boiler efficiency and explain briefly?
15. How do you assess boiler blow down requirement?
16. Discuss automatic blow down control system?
17. Why blow down is given in boiler?
18. What is the function of de-aerator in boiler?
19. What is the difference between an economizer and an air pre heater?
20. List the 5 energy conservation measures in improving the boiler efficiency without investment.
21. What is intermittent and continuous blow down?
22. Why is sulphur in coal undesirable?
23. Is moisture in coal wasteful?
24. What is atomisation of fuel oil in combustion?
25. What are the causes for heavy black smoke in a boiler?
Ch-02.qxd 2/23/2005 11:21 AM Page 53
26. 1 kg of water at 25°C is converted in to steam at atmospheric condition. What is the value of sensible heat and latent heat added to the steam?
27. For boiler at 8 kg/cm2 (g) steam pressure. The following details are given Saturation temperature of steam = 170°C
Sensible heat of water = 171 kCal/kg
Latent heat of evaporation = 490 kCal/kg
Moisture content in the steam = 4%
What is the total heat content of the steam?
28. The following are the ultimate analysis for coal: Calculate the stoichiometric air requirement.
Carbon-38%, Ash-35%, Hydrogen-5% , Sulphur-2%.
For the same data, calculate the theoretical CO2.
If the actual measured CO2 is 8%, find out the excess air levels?
29. A packaged boiler is operating at 5% O2. Find out the excess air level?
30. In a furnace oil fired boiler, the evaporation ratio (kg of steam generated / kg of fur- nace oil) was found to be 20 against a best possible limit of 13. (a) in your opinion what could be the reasons for the same? (b) would you like to recommend the user to maintain the same practice and conditions as the evaporation ratio is more than the feasible limit?
54Bureau of Energy Efficiency
Ch-02.qxd 2/23/2005 11:21 AM Page 54