Question

During carbonisation or destructive distillation of coal, bituminous coal is heated in iron or fireclay retorts to high temperature (500 deg C) in presence of air.
A. True
B. False

Answer 1

Hint: Destructive distillation is a technique where the unprocessed materials are decomposed by heating at high temperature with fewer amounts of oxygen, catalyst and other reagent. Destructive distillation is an application of pyrolysis where a crack is made in the large molecules.

Complete answer:Given
In destructive distillation of bituminous coal, the nature of the product depends on the temperature at which the process takes place and the process is carried out in the absence of air. When temperature of 450 ${}^{o}C$ to 500 ${}^{o}C$ is applied to the coal, the products formed are gas and oily vapours usually containing paraffin hydrocarbon. When the coal is heated at temperature 700 ${}^{o}C$ to 800 ${}^{o}C$ more gas is evolved mostly containing hydrogen gas. When paraffin is heated further it generates hydrogen and methane with traces of ethane and ethylene.
The coal is heated in a retort which is made of iron; nowadays it is made of fire clay. Horizontally, it is D-Shaped 20Ft long in cross section. The process of carbonization usually takes upto 12 hours and the temperature goes upto 1100 ${}^{o}C$.
Thus the statement, during carbonisation or destructive distillation of coal, bituminous coal is heated in iron or fireclay retorts to high temperature (500 ${}^{o}C$) in presence of air is FALSE.

Note:
The three main constituents are obtained when the volatile products obtained by heating of coal passes by a wide pipe where partial cooling takes place, they are impure coal gas, ammoniacal liquor and tar. When coal is heated in the availability of air, only carbon dioxide gas is obtained and no other products are obtained.