Environmental and Economic Aspects of the Plasma Treatment of Scrap Tires to Produce Syngas and Synthetic Fuels in Saudi Arabia

Kingdom of Saudi Arabia (KSA) has been chosen for thermal plasma treatment using a plasma torch attached to plasma reactor, with flow rate of air 10-30 mg/s and mean temperature of the plasma jet at the torch exhaust nozzle 7000-19 000 K; the air plasma torch parameters are easily tunable to produce a suitable plasma jet for the treatment of scrap tires. The calculated cold gas efficiency of the proposed plasma treatment system for scrap tires feedstocks is 82.72%. The average weight of scrap tires in KSA is 218 500 t per year. After plasma treatment, the heat energy per ton produced annually from scrap tires in KSA is 475.4 TJ. The 16 t of synthetic syngas is enough to produce 50 013 MJ/day converted into electricity 13 972.6 kWh/day, and the 80 t of slag is enough for different industrial products. The total annual gross profit for all the products (pyrolysis oils, synthetic syngas, and slag) is $28.19 million, while the gross annual cost is $9.202 million with a cash recovery period of 1.36 years, neglecting the income tax.