Pyrolysis is the heating of organic material, such as biomass, in the absence of oxygen. Because no oxygen is present the material does not combust. But the chemical compounds (i.e. cellulose, hemicellulose, and lignin) thermally decompose into combustible gases and charcoal.
Pyrolysis of Tyres
It mainly involves the thermal degradation of tire rubber at high temperatures (250–900°C) in an oxygen absent environment. It can be performed under vacuum or atmospheric pressure
Process
The biomass pyrolysis process consists of both simultaneous and successive reactions. When organic material is heated in a non-reactive atmosphere. Thermal decomposition of organic components in biomass starts at 350 °C–550 °C and goes up to 700 °C–800 °C in the absence of air/oxygen. The long chains of carbon, hydrogen, and oxygen compounds in biomass break down into smaller molecules in the form of gases, condensable vapors (tars and oils), and solid charcoal under pyrolysis conditions. The rate and extent of decomposition of each of these components depends on the process parameters of the reactor temperature, biomass heating rate, pressure, reactor configuration, feedstock, etc
Depending on the thermal environment and the final temperature, pyrolysis will yield mainly biochar at low temperatures, less than 450 0C, when the heating rate is quite slow, and mainly gases at high temperatures, greater than 800 0C, with rapid heating rates. At an intermediate temperature and under relatively high heating rates, the main product is bio-oil.
Product Obtained:
The processes can be categorized as slow or fast. But Slow pyrolysis takes several hours to complete and results in biochar as the main product. On the other hand, fast pyrolysis yields 60% bio-oil and takes seconds to complete the process. In addition, it gives 20% biochar and 20% syngas. It currently the most widely used pyrolysis system.
