Fuels And Combustion - Practice Test

(A) Indian coals on an average contain 25-30% ash as against 10-12% ash in imported coking coal

(B) Ammonia is recovered in the form of ammonium sulphate in direct process of by-product recovery

(C) A high swelling index number of coking coal indicates poor caking properties of coal

(D) Wash oil is used for scrubbing benzol from coke oven gas

(E) Angle of repose of coal increases with its increasing size

(F) Specific gravity of coal increases with its increasing maturity

(G) Refractive index and reflectance of coal increases with the increasing rank of coal

(H) Specific heat of coal decreases with increases in the volatile matter and decrease in the C/H ratio of coal

(I) High concentration of oxygen in flue gas means high stack loss

(J) Gaseous fuels require the least % excess air for complete combustion

(K) The ratio of fixed carbon to volatile matter percentage in coal is called its 'fuel ratio'

(L) Calorific value of natural gas is more than that of LPG

(M) Main constituents of LPG are propane and butane

(N) C.V. of natural gas is about 10000 kcal/Nm 3

(O) C.V. of LPG is about 26000 kcal/Nm 3 (11500 kcal/kg)

(P) LPG is lighter than air

(Q) Percentage of ash in coke produced from medium coking coal is more than that in coal

(R) The calorific value (kcal/Nm 3 ) of coke oven gas reduces on removal of hydrogen from it by cryogenic method

(S) Ash is normally removed as

(T) Coal based fertiliser plants in India at Talcher (Orissa) and Ramagundam (A.P.) employ Kopper-Totzek process of coal gasification

(U) Pulverised fuel can be completely burnt with less percentage of excess air compared to lump coal

(V) Low grade coal can be used, but generally high volatile matter coals are more suitable for making pulverised fuel

(W) Regulation of furnace temperature and atmosphere (oxidising or reducing) is easily possible with pulverised fuel firing

(X) None of these

(Y) Theoretical flame temperature is the temperature attained by the products of combustion, when the fuel is burned without loss or gain of heat

(Z) Burning the fuel with theoretically required amount of pure oxygen results in attainment of maximum adiabatic flame temperature

([) Burning the fuel with excess pure oxygen results in maximum theoretical flame temperature

(\) Adiabatic flame temperatures of actual combustions are always less than the maximum values

(]) LPG is also used as fuel for automobiles & small furnaces and for cutting & welding of metals

(^) The minimum temperature, at which a petroleum oil vapor catches fire and continues to burn, is called its flash point

(_) Each ton of petroleum oil on distillation produces about 30 - 50 Nm 3 of gas

(`) Maximum yield of naphthalene is obtained on distillation of crude oil

(a) Cokes of high reactivity are obtained from weakly coking coals

(b) Cokes of high reactivity are obtained from strongly coking coals

(c) Reactivity of coke is inversely proportional to its absolute density

(d) Abrasion index of the coke is a measure of its hardness

Fuels And Combustion - Study Mode