The function of an economiser in a boiler is to preheat the _____________________?

Related Mcqs:

1. Design of waste heat boiler for recovery of waste heat from furnace gases depends upon the_________________?

   A. Quantity & temperature of waste gas
   B. Dust concentration & nature of dust in waste gas
   C. Corrosive nature of the waste gas
   D. All A., B. and C.

2. Maximum thermal efficiency of boiler may be about _____________ percent?

   A. 10
   B. 25
   C. 65
   D. 90

3. Amount of coal lost in ash particle, which is carried through the boiler system, depends upon the__________________?

   A. Physical nature, ash content and fineness of the coal
   B. Amount of excess air supplied and load on the boiler
   C. Type of burner and combustion chamber
   D. All A., B. and C.

4. 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

5. 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. Higher power consumption in its transportation
   D. Erosion of induced draft fan blades

6. The main function of a muffle in the muffle furnace is to__________________?

   A. Protect the charge from the effects of the products of combustion
   B. Smooth out temperature inequalities on the combustion side of the muffle wall
   C. Both A. & B.
   D. Neither A. nor B.

7. In salt bath furnace, heat is transferred to the charge mainly by __________________?

   A. Conduction
   B. Convection
   C. Radiation
   D. None of these

8. Presence of SO2 in furnace gases attacks the ferrous metal by way of_________________?

   A. Accelerating the rate of scaling
   B. Causing metal embrittlement
   C. Attacking the grain boundaries; particularly severe on low carbon and nickel bearing steels at
   high temperature
   D. All A., B. and C.

9. Which is not accomplished in an underfired furnace ?

   A. Increase in heating capacity/m2 of floor space
   B. Elimination of cold spot at the bottom of the charge
   C. Reduction in the temperature of furnace gases
   D. Protection of the periphery of the charge from excessive radiation

10. Reducing atmosphere is maintained in a__________________?

    A. Calcination kiln
    B. Blast furnace
    C. Soaking pit
    D. L.D. converter