Scaling of furnace stock is reduced by _______________ in flue gas?

Related Mcqs:

1. Combustion of furnace oil in a furnace (soaking pit) with preheated combustion air at 400°C results in saving of about __________ percent furnace oil as compared to its combustion with atmospheric air, if the flue gas outlet temperature from the soaking pit is 1200°C ?

   A. 5
   B. 60
   C. 20
   D. 40

2. In a furnace, the heat taken by the charge/stock and the heat lost to the furnace structure & flue gases depends on the__________________?

   A. Rate of firing and emissivity of flame
   B. Thermal conductivity of the charge & structural materials of furnace
   C. Nature of process; whether batch, continuous or intermittent
   D. All A., B. and C.

3. The rate of scaling of furnace stock depends upon the_________________?

   A. Temperature
   B. Time
   C. Nature of atmosphere
   D. All A., B. and C.

4. Which furnace employs an I.D. fan for the removal of flue gases from the furnace ?

   A. Coke oven
   B. Blast furnace stoves
   C. Beehive coke oven
   D. High pressure boiler

5. Flue gas outlet temperature from the chimney of any furnace should be ideally about ______________ °C?

   A. 50
   B. 100
   C. 150
   D. 250

6. Oxygen percentage in the flue gas coming out of a gaseous fuel fired furnace should be ideally about _____________ percent?

   A. < 2
   B. < 5
   C. < 8
   D. < 10

7. In practical operation of any furnace, zero oxygen percentage or theoretical CO2 percentage in flue gas is rarely achieved, because of__________________?

   A. Use of non-preheated combustion air
   B. Use of pulverised solid fuels
   C. Imperfect mixing of fuel & air and infiltration of air
   D. Use of excessive positive draft in the furnace

8. Out of the following fuels used in a furnace exhausting flue gas at a temperature of 600°C, the percentage stack loss will be maximum in case of complete combustion of_________________?

   A. Furnace oil with air
   B. Furnace oil with oxygen
   C. Blast furnace gas with air
   D. Blast furnace gas with oxygen

9. Higher furnace temperature cannot be achieved by use of a lean fuel gas in the furnace by_________________?

   A. Increasing the draft in the furnace
   B. Preheating the fuel gas
   C. Oxygen enrichment of combustion air
   D. Preheating the combustion air

10. Which of the following is not an additive for flue gases from furnace to reduce its dewpoint ?

    A. Ammonia
    B. Fine dolomite
    C. Alkaline powders
    D. None of these