Pyrolysis of Tyres

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Every year the world produces over one billion used tyres. Only a small portion of these tyres are recycled. For example, in Australia only 5% of used tyres go through a recycling process; 13% are dumped illegally, and the remaining of tyres goes to landfill which, by far, is the worst option environmentally.

Without sunlight one tyre would take up to 30,000 years to degrade, taking up valuable space, providing havens for vermin and mosquitoes, and posing a fire hazard.

Burning one ton of waste tyres produce about 450 kg of toxic gases. The damage to the environment is obvious. Due to the high calorific value in tyres scrap, the most beneficial, and profitable resource recovery option for recycling tyres is the Thermal Recovery Unit (TRU) Pyrolysis.

TRU Pyrolysis refers to the thermal decomposition of tyres scrap in the absence of oxygen. This recycling process aims to recover the carbon black, and steel, and also capture the hydrocarbons as syngas.

Tyre recycling through a TRU plant would first involve shredding the tyres, magnetically, removing the steal, and then crumbing the tyres to a particle size of less than 3cm. The tyres are fed directly into the TRU hopper, then passed through a rotary airlock before entering into the primary retort.

The syngas from the TRU process has a very high calorific value that may be used for steam, and power production. Furthermore, the TRU recovers up to 38% of the tyres weight in carbon char (biochar). Biochar is a valuable commodity with great on-sell potential. It is used in agriculture for soil amendment and can also be used as re-activated carbon.

The syngas produced by the TRU is immediately drawn into a thermal oxidiser where it is mixed with oxygen and combusted. This process eliminates most toxic gases resulting in clean emissions. The thermal energy created by this combustion may be used to produce steam for a variety of applications, including cogeneration and the production of green power.

An alternative to the flaring of the syngas for thermal energy is to turn it to bio-diesel and hydrocarbons. These fuels may be used in piston engines as an alternative to diesel and gasoline.

 

References
pyrolysis.biz
wastetyrerecycleplant.com/
afrinc.com

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