Pyrolysis, slow charcoal

Pyrolysis of biomass is divided into slow pyrolysis, which is well known to produce charcoal, for example, fast pyrolysis, which produces a high yield of liquid biofuels and other chemicals (Bridgwater, 2000) and flash pyrolysis. Slow pyrolysis (or carbonisation) requires low temperatures and very long residence time. In the carbonisation process the amount of char is maximised. 

Conventional pyrolysis (slow pyrolysis), proceeds under a low heating rate with solid, liquid and gaseous products in significant portions [16,18]. It is an ancient process used mainly for charcoal production. Vapours can be continuously removed as they are formed. 

Slow pyrolysis, also called carbonization, is characterized by a high charcoal yield and is not considered for hydrogen production processes. The slow pyrolysis of wood (24 h typical residence time) was a common industrial technology to produce charcoal, acetic acid, methanol, and ethanol from wood until the early 1900s. 

Pyrolysis is a type of gasification that breaks down the biomass in oxygen deficient environments, at temperatures of up to 400°F. This process is used to produce charcoal. Since the temperature is lower than other gasification methods, the end products are different. The slow heating produces almost equal proportions of gas, liquid and charcoal, but the output mix can be adjusted by changing the input, the temperature, and the time in the reactor. The main gases produced are hydrogen and carbon... 

The effect of the physical characteristics of wood on slow pyrolysis or carbonization has thus been quite extensively studied. However, these studies focus mainly on the qualitative effects of the physical parameters of the material. The optimization of the carbonization process as operated by charcoal producers around the world requires quantitative relations, particularly regarding mass and energy flows as determining operational parameters of a dynamic process such as carbonization. 

MPa in the absence of air to convert biomass into liquid oils, solid charcoal and gaseous compounds (Ni et al., 2006). Pyrolysis can be classified into slow and fast pyrolysis, whereby only the latter is considered for hydrogen production according to the following reaction scheme ... 

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