The process ofpyrolysiscan be conducted in a distillation apparatus (retort) to form the volatile products for collection. The mass of the product will represent only a part of the mass of the feedstock, because much of the material remains as char and non-volatile tars. This is in contrast to simplecombustion, where the fuel is oxidized; typically thecombustionproducts of ahydrocarbonfuel amount to roughly four times the mass of the fuel consumed.
Destructive distillation and related processes are in effect the modern industrial versions of traditionalcharcoalburning crafts. As such they are ofindustrial significancein many regions, such as Scandinavia. The modern processes are sophisticated and require careful engineering to produce the most valuable possible products from the available feedstocks.Destructive distillationis thechemical processof thedecompositionoffeedstockby heating it to a high temperature; the term generally applies to processing oforganicmaterial in the absence of air or in the presence of limited amounts of oxygen or otherreagents,catalysts, orsolvents, such assteamorphenols. It is an application ofpyrolysis. The process breaks up or'cracks'large molecules.Coke,coal gas,gas carbon,coal tar,ammonia liquor, and "coal oil" are examples of commercial products historically produced by the destructive distillation of coal.