Means for giving direction to the circulation of gases in furnaces are_____________________?

A. Use of coal/coke containing a high % of fines and ash
B. Use of fuel having too low an ash fusion temperature
C. Development of hot spots in the fuel bed and an abnormally high rate of gasification
D. All A., B. and C.

A. Higher calorific value
B. Better combustion
C. Smokeless burning
D. Less erosion on furnace wall

A. Size of the furnace
B. Gas velocity in furnace
C. Ratio of wall surface to surface of stock
D. None of these

A. Fusion of coal ash & clinker formation
B. C. V. of producer gas
C. Temperature of producer gas
D. Tar content in producer gas

A. Waste heat recovery from flue gas
B. Minimising heat losses from furnace walls
C. Maintaining proper draught
D. All A., B. and C.