Output Ratio (pyrolysis output ratio)

Output Ratio in pyrolysis is the mass-balance breakdown of the four product fractions — pyrolysis oil, non-condensable gas, carbon black (char), and steel wire — produced per 100 kg of feedstock. For end-of-life tyres processed in an Indian batch or rotary kiln operating at 400–500°C, the typical ratio is 40–45% oil, 30–35% carbon black, 10–15% gas, and 10–15% steel. For mixed waste plastic pyrolysed at 380–450°C, the split shifts to 60–75% oil, 10–20% gas, and 5–15% char with no steel fraction.

The ratio is not a fixed property of the feedstock — it is a design specification driven by reactor temperature profile, residence time, heating rate, and feedstock preparation. Higher temperatures (above 550°C) crack the oil into more gas, raising gas yield to 25% and lowering oil to 30%. Slow heating (below 10°C per minute) favours char formation, while flash heating (above 100°C per second) maximises oil. Adding catalysts such as zeolites or red mud during plastic pyrolysis can lift the diesel-range fraction of the oil from 40% to 65%, although this is rarely used in Indian commercial plants because of cost.

Output ratio directly determines plant economics. Tyre pyrolysis oil sells at ₹35–45 per litre in Indian industrial fuel markets, carbon black at ₹15–25 per kg (raw, non-ASTM grade), and scrap steel at ₹28–35 per kg. A 10 tonne-per-day tyre plant with a 45/35/10/10 ratio generates roughly ₹2.1–2.4 lakh of daily revenue, while a poorly tuned plant at 35/40/15/10 loses ₹30,000–50,000 per day in foregone oil sales.

• Output ratio = mass of each product fraction divided by mass of feedstock input, summed to 100%.
• For tyres: oil 40–45%, char 30–35%, gas 10–15%, steel 10–15% under typical Indian batch operation.
• For plastics: oil 60–75%, gas 10–20%, char 5–15% — no steel fraction.
• Temperature, residence time, and heating rate are the three primary control levers.