Which of the following will be unsuitable for dust cleaning from flue gas at 400°C from a pulverised coal fired boiler ?

Related Mcqs:

1. In case of pulverised coal fired steam boiler, the secondary air serves the main purpose of__________________?

   A. Transportation of coal
   B. Drying of coal
   C. Combustion of coal by supplying it around the burner
   D. Preheating the primary air

2. The main function of primary air in pulverised coal fired burner is to_________________?

   A. Burn CO to CO2
   B. Dry and transport the coal
   C. Have proper combustion by supplying it around the burner
   D. Preheat the tertiary air used for complete combustion of CO to CO2

3. Which of the following is the most important deterrents to an extended use of pulverised coal in boiler firing ?

   A. Ash disposal problem
   B. Excessive fly-ash discharge from the stack
   C. High power consumption in its transportation
   D. Erosion of induced draft fan blades

4. Coal is pulverised before burning in large capacity boiler furnaces mainly to____________________

   A. Ensure its complete combustion
   B. Facilitate easy ash removal
   C. Enhance its calorific value
   D. Provide trouble free operation

5. Use of pulverised coal in boiler furnace provides___________________?

   A. High calorific value
   B. Better combustion
   C. Smokeless burning
   D. Less erosion on furnace walls

6. Temperature of preheated air used for the transportation of pulverised coal through pipes to the burner of a boiler furnace is restricted to a maximum limit of about 300° C to avoid the___________________?

   A. Requirement of large volume combustion chamber
   B. Risk of explosion
   C. Chances of clinker formation
   D. Incomplete combustion of coal

7. Pulverised coal used in boiler firing need not have____________________?

   A. Less moisture content
   B. High fusion point of its ash
   C. High bulk density
   D. Lower ash content

8. Dust content in raw blast furnace gas is about _______________ gm/Nm3; hence it is cleaned to the dust level of about < 10 mg /Nm3 before use?

   A. 15-30
   B. 1-2
   C. 70-100
   D. 150-200

9. ombustion of pulverised coal compared to the lumpy coal __________________?

   CA. Provides better control of furnace temperature
   B. Facilitates combustion with lower excess air
   C. Provides higher thermal efficiency & flame temperature
   D. All A., B. & C.

10. Combustion of pulverised coal as compared to that of lump coal ________________?

    A. Develops a non-luminous flame
    B. Develops a low temperature flame
    C. Can be done with less excess air
    D. Provides a lower rate of heat release