Chapter 7

  1. Draft in a furnace depends on: 
    1.  The temperature of atmospheric air
    2.  The height of the stack
    3.  The pressure in the furnace chamber
    4.  The temperature of the gases in the stack




    E.   1, 2, 4
  2. Draft is a term that indicates: 




    B.   Static pressure
  3. In a boiler duct, pressure drop through a restriction is used to:
    a. Measure the draft
    b. Measure the air flow
    c. Measure the density
    d. Measure the secondary air pressure
    e. measure air temperature
  4. Natural draft is the difference in pressure caused by:




    C. the height of the stack
  5. Advantages of mechanical draft are:
    1. Better purging of boiler
    2. Less expensive stack can be used
    3. Less supervision during operation
    4. Increases unit efficiency




    D. 1, 2, 4
  6. Disadvantages of mechanical draft are:
    1. Higher initial cost
    2. Closer supervision is required
    3. More expensive stack must be used
    4. Draft is dependent on atmospheric conditions




    A. 1, 2
  7. The __________ fan provides the volume of combustion air to the boiler.



    A. forced draft
  8. The __________ fan provides the volume of combustion air to the boiler.



    B. forced draft
  9. The __________ fan is used to remove the hot flue gases from the boiler.



    C. induced draft
  10. When furnace draft is maintained at atmospheric pressure (or just below), the draft is referred to as:




    D. Balanced draft
  11. The instruments used to monitor the air and flue gas system in a boiler consist of instruments that measure:
    1. Pressure
    2. Temperature
    3. Density
    4. Flow




    A. 1, 2, 4
  12. Draft is measured in:




    E. cm of wg
  13. A simple gauge for measuring draft consists of a glass U tube containing water. This type of gauge is known as a _________.



    A. manometer
  14. A type of gauge that has superseded the U tube for measuring boiler draft is the ________ gauge.



    C. diaphragm
  15. Draft fans can be divided into the following types:
    1. Backward curved blade
    2. Air foil curved blade
    3. Straight blade
    4. Forward curved blade




    B. 1, 2, 3, 4
  16. Which of the following types of fan blades would have the lowest tip velocities?




    A. Forward curved blades
  17. Draft fan output is controlled by:
    1. Variable speed
    2. Inlet damper control
    3. Outlet damper control
    4. Variable area for blades




    C. 1, 2, 3
  18. One advantage of inlet vanes to control the output of an I.D. fan is:



    D. Air entering the fan receives a spin in the direction of wheel rotation
  19. The most efficient method of controlling an I.D. or F.D. fan on output is:




    D. Variable speed control
  20. The windbox is an extension of the air ducts and serves as a __________ chamber for the air.



    C. distributing
  21. Louvers are installed in the ________ to direct the air to the base of the flame.



    D. windbox
  22. When a boiler is burning solid fuels, the primary air is usually admitted:




    B. Under the fuel bed
  23. When a boiler is burning solid fuels, the secondary air is usually admitted:




    B. Through the fuel bed
  24. Solid pollutants are dust particles known as ash, consisting mainly of the __________ parts of the fuel.



    A. non-combustible
  25. In modern pulverized coal firing facilities, the high __________ between the coal and the combustion air stream causes most of the ash to be carried over with the stack effluents.



    A. turbulence
  26. The theory of particle precipitation is based on the fact that, when a moving particle changes its ________, a force is generated as a consequence.



    B. velocity
  27. In a cyclone precipitator a spray of water turns the individual dust particles into heavy mud particles.
    a. True
    b. False
    a. True
  28. Dust laden flue gas from the boiler enters the _________ precipitator that contains a charging electrode. The dust particles receive a charge of electricity and become electrified.



    C. electrostatic
  29. The __________ use several filter bags, in parallel, and the principle is the same as that of the domestic vacuum cleaner. The fabric of the bags is large enough to allow the flue gas molecules to pass through but small enough to catch the dust particles.



    C. bag houses
  30. The type of _____ _____ system used at a plant depends upon the method of firing and the size of the plant.



    C. ash handling
  31. A small plant firing with ______ may be arranged so that trucks can be driven into the basement and the ash from the ash pit dumped directly into them.



    D. stokers
  32. __________ systems often use jet pumps to move a mixture of water and ash to the disposal area, via a closed pipeline.



    A. Hydro
  33. A __________ system moves the ash in a stream of air, or flue gas.



    B. pneumatic
  34. The __________ system involves the use of solids handling equipment, such as scraper conveyors, bucket elevators, and conveyor belts.



    A. mechanical
  35. Recovery systems, for the removal of SO2 can be classified into two major types:



    B. wet, dry
  36. In the ____ scrubbing system, a solution of lime/limestone slurry contacts the sulphur dioxide laden flue gas.



    C. wet
  37. In the ____ scrubbing process, the heat of the flue gas is used to dry finely atomized slurry of alkaline reactants.



    B. dry
Author
PowerPrep
ID
317565
Card Set
Chapter 7
Description
Chapter 7
Updated