A. Are soft & friable (poor strength and size stability)
B. Require longer time of carbonisation as ash offers resistance to heat transfer
C. Produce larger quantity of coke oven gas
D. None of these
Related Mcqs:
- ‘Fat coals’ are those coals which have very high____________________?
A. Caking capacity
B. Volatile matter content
C. Fusion point of its ash
D. Inherent moisture content - Ash content in the coke produced from a coking coal having 20% ash may be around _____________ percent?
A. 6
B. 12
C. 18
D. 24 - Fusion point of coal ash generally varies from 1000 to 1700° C. Ash having fusion point less than _______________ °C is liable to form clinker?
A. 1100
B. 1250
C. 1350
D. 1400 - Coals used for the generation of producer gas should have ____________________?
A. High caking index
B. Low fusion point of ash
C. High volatile matter content
D. Very low ash content (8-10%) - Assam (India) coals suffers mainly from the disadvantage of high ______________ content?
A. Ash
B. Volatile matter
C. Sulphur (4-6%)
D. Moisture - A coal with high ash content is undesirable, as________________?
A. It is abrasive to the coal pulveriser (i.e. ball mill) and the combustion chamber
B. The ash in molten condition gets absorbed in the pores of the refractory lining of the furnace
and causes its spalling due to different co-efficient of expansion/contraction of the refractory
and the ash
C. The ash retains the sulphur & phosphorus and thus affects the quality of products in
metallurgical furnace apart from increasing the slag volume. Besides, it may fuse and stick to
the boiler tubes thereby reducing the heat transfer
D. All A., B. and C. - A coal with high ash content___________________?
A. Has higher calorific value
B. Is harder and stronger
C. Is not subjected to washing
D. Has low quantity of mineral matter - Gasification of the solid fuel converts its organic part into combustible by interaction with air/oxygen and steam so as to obtain a secondary gaseous fuel of high calorific value having no ash. Gasification reactions are normally carried out at about _____________ °C?
A. 400-500
B. 900-1000
C. 1400-1500
D. 1700-1800 - High ash containing coke____________________?
A. Produces more slag when used in the blast furnace
B. Has poor strength and abrasion resistance
C. Is desirable in producer gas manufacture
D. None of these - Very ______________ coals are completely devoid of cokability i.e., it is non-coking ?
A. Young
B. Mature
C. Both A & B
D. Neither A nor B
