Tire Pyrolysis Plant Product

Overview

Tire pyrolysis is a thermal decomposition process that breaks down scrap tires in the absence of oxygen (anaerobic conditions) at temperatures of 400–600 °C. The process yields three products: pyrolysis oil (a dark, fuel-quality liquid), carbon char (solid residue), and combustible gas. Modern tire pyrolysis addresses the global waste-tire crisis: over 1.5 billion scrap tires are generated annually; landfill disposal is space-intensive and environmentally problematic; tire-derived fuel (TDF) incineration releases particulates and air pollution. Pyrolysis recovers chemical energy as usable oil and char while minimizing air emissions.

A tire-pyrolysis plant processes 30–50 tonnes of scrap tires daily, generating 12–20 tonnes of pyrolysis oil, 10–15 tonnes of char, and 8–12 tonnes of combustible gas. The oil can be burned as fuel oil or processed into diesel fuel. The char is sold as carbon black feedstock or fuel. The gas is primarily recycled into the burner to provide heat, reducing external fuel requirements and improving energy efficiency.

How it works

Tire Feed and Shredding

Whole scrap tires arrive at the plant and are fed into a [[tire-pyrolysis-plant-tire-shredder|tire shredder]] (15 kW motor, 50 mm max output). The shredder reduces tires to chips allowing faster and more uniform heating inside the reactor. Shredded tire material drops into a [[tire-pyrolysis-plant-feed-hopper|2 m³ surge hopper]].

A [[tire-pyrolysis-plant-feed-screw|variable-speed metering screw]] (3 kW motor, 0–150 kg/h variable speed) controls feed rate into the [[tire-pyrolysis-plant-rotary-reactor|rotary reactor]]. A pneumatic [[tire-pyrolysis-plant-reactor-inlet-valve|inlet check valve]] prevents reactor vapors from backing up into the feed hopper.

Pyrolysis Reaction in Rotary Reactor

The [[tire-pyrolysis-plant-rotary-reactor|rotary reactor]] is a tilting cylindrical vessel (5000 L capacity, 2.5 m diameter) lined with [[tire-pyrolysis-plant-refractory-lining|high-temperature ceramic bricks]] (100 mm thickness, rated 1000 °C). The reactor exterior is jacketed with a [[tire-pyrolysis-plant-heat-exchanger-jacket|double-wall cooling/heating jacket]].

A [[tire-pyrolysis-plant-rotation-motor|rotation motor]] (5.5 kW, 1800 rpm input) drives a [[tire-pyrolysis-plant-rotation-gearbox|300:1 reduction gearbox]] that rotates the reactor drum at 4–6 rpm. This slow rotation ensures continuous mixing and uniform heat distribution without excessive dust generation or material damage.

Heat is supplied by a [[tire-pyrolysis-plant-gas-burner|dual-fuel burner]] (200 kW capacity) mounted outside the reactor. The burner combusts natural gas mixed with [[tire-pyrolysis-plant-gas-recirculation|recycled pyrolysis gases]], providing sustained heat to reach and maintain 400–600 °C. A [[tire-pyrolysis-plant-heat-fluid-pump|circulation pump]] (22 kW) circulates [[tire-pyrolysis-plant-heat-transfer-fluid|synthetic heat-transfer oil]] through the jacket at 5 bar, transferring burner heat to the reactor walls.

As tire chips are heated, polymer chains in the rubber break down (thermal cracking) into lighter hydrocarbons: liquid oils, lighter vapors, and hydrocarbon gases. The reaction is endothermic (energy-consuming), requiring continuous heat input. Residence time is typically 60–90 minutes; longer times increase oil yield but consume more fuel.

Vapor Condensation and Oil Recovery

Pyrolysis vapors exit the reactor at ~300–350 °C and flow into a [[tire-pyrolysis-plant-condenser-train|multi-stage condenser system]]. The [[tire-pyrolysis-plant-primary-condenser|primary condenser]] (shell-and-tube cooler, 50 kW cooling capacity) is water-cooled, reducing vapor temperature to ~100 °C. Heavy oil vapors condense into liquid droplets.

A [[tire-pyrolysis-plant-secondary-condenser|secondary condenser]] (air-cooled finned tube) further cools the stream to ~40 °C, condensing all remaining vapors. A [[tire-pyrolysis-plant-oil-separator|gravity-separation tank]] (500 L capacity) collects condensed pyrolysis oil in the bottom; water and light organics separate and drain from the top. The oil product is dark brown, viscous (similar to heavy fuel oil), with approximately 43 MJ/kg heating value (comparable to diesel fuel but slightly higher sulfur content).

The [[tire-pyrolysis-plant-condenser-pump|cooling pump]] (50 m³/h) recirculates cooling water through the condensers, rejecting heat to a [[tire-pyrolysis-plant-cooling-tower|cooling tower]] (100 kW capacity) that evaporatively cools the water and rejects heat to the atmosphere.

Char Cooling and Collection

Char (solid carbon residue, 30–40% by weight) falls through the reactor during the pyrolysis batch cycle. As the batch nears completion and temperature is reduced to ~300 °C, the operator gradually tilts the reactor using a [[tire-pyrolysis-plant-tilt-cylinder|hydraulic tilt cylinder]] (double-acting, tilting to 30°), causing char to slide out into a [[tire-pyrolysis-plant-char-screw|water-jacketed cooling screw]].

The [[tire-pyrolysis-plant-char-conveyor-motor|screw motor]] (7.5 kW, variable speed) rotates the screw at 20–30 rpm. Cooling water circulates through the screw jacket, reducing char temperature from ~300 °C inlet to <50 °C outlet over approximately 3 minutes of residence time. The cooled char drops into a [[tire-pyrolysis-plant-char-collection-hopper|10 m³ collection hopper]] with a [[tire-pyrolysis-plant-char-vibrator|pneumatic vibrator]] assisting discharge.

Char is sold as carbon black feedstock for tire manufacturing or as a premium fuel (60% higher heating value than raw coal due to porosity and carbon content).

Non-Condensable Gas Recovery

Non-condensable gases exiting the secondary condenser (primarily hydrogen H₂, methane CH₄, and ethane C₂H₆, totaling 20–30% by weight of feed) are recycled into the [[tire-pyrolysis-plant-gas-recirculation|gas burner]]. The burner operates on a dual-fuel logic: if pyrolysis gas pressure is sufficient, the burner runs primarily on recycled gas; if pressure drops (early in a batch cycle), the system automatically switches to natural gas.

A [[tire-pyrolysis-plant-gas-compressor|burner blower]] (3 kW) supplies combustion air and maintains slight back-pressure (0.5 bar) on the reactor, preventing oxygen ingress and maintaining anoxic (oxygen-free) conditions critical for the pyrolysis reaction.

Any excess gas (beyond burner capacity) is vented through a [[tire-pyrolysis-plant-pressure-relief-valve|spring-loaded relief valve]] (2 bar setting) to a [[tire-pyrolysis-plant-flue-gas-treatment|flue-gas treatment system]] (scrubber and bag filter, off-site integration) for emissions control.

Batch Cycle Management

Loading phase (10 minutes): Tire chips are fed into the reactor via the [[tire-pyrolysis-plant-feed-screw|feed screw]] at 100–150 kg/h until the reactor reaches 80% fill (approximately 5 tonnes of shredded tire).

Heating phase (30–40 minutes): The [[tire-pyrolysis-plant-gas-burner|burner]] ramps to full power. The reactor temperature rises from ambient to 400 °C, initiating pyrolysis. Vapors begin condensing in the condenser system; oil begins accumulating in the separator tank.

Residence phase (60–90 minutes): The reactor maintains 500–550 °C. Continuous rotation ensures thorough mixing. Vapor generation peaks during this phase. The burner maintains setpoint temperature; if temperature rises above setpoint, the [[tire-pyrolysis-plant-plc|PLC]] reduces burner fuel flow via proportional valve.

Cooling phase (20–30 minutes): The burner is shut down. The reactor continues rotating; heat is passively lost through the refractory lining. Temperature drops to ~300 °C, at which point char discharge begins.

Char discharge (5–10 minutes): The [[tire-pyrolysis-plant-tilt-cylinder|tilt cylinder]] is activated, tilting the reactor 30° and sliding char into the [[tire-pyrolysis-plant-char-screw|cooling screw]]. The screw runs continuously, ejecting cooled char into the hopper.

Oil/water separator drawdown (5 minutes): Accumulated pyrolysis oil is drained from the bottom of the [[tire-pyrolysis-plant-oil-separator|oil separator tank]] into a collection drum or tank truck. Water and light organics are drained from the top.

Total cycle time: 120–150 minutes per 5-tonne batch.

Control and Safety

A [[tire-pyrolysis-plant-control-system|programmable logic controller]] monitors all critical parameters:

• Reactor temperature: Three [[tire-pyrolysis-plant-temperature-sensor|Type-K thermocouples]] (inlet, center, outlet) provide feedback; the PLC maintains 500–550 °C via proportional burner control.
• Reactor pressure: A [[tire-pyrolysis-plant-pressure-sensor|pressure transducer]] (0–10 bar) monitors reactor pressure, which naturally rises to 0.5–2 bar during pyrolysis as gases are generated. A [[tire-pyrolysis-plant-pressure-relief-valve|relief valve]] (2 bar setting) vents excess pressure.
• Oil level: [[tire-pyrolysis-plant-level-sensor|Capacitive level sensors]] detect when the oil separator tank is full or empty.
• Char level: A level sensor in the char hopper triggers discharge-gate opening when full.

A [[tire-pyrolysis-plant-display-panel|color HMI touchscreen]] displays all parameters in real-time and logs historical data. The [[tire-pyrolysis-plant-emergency-stop|emergency stop button]] (red 40 mm mushroom, dual-channel safety-rated) immediately shuts down the burner and stops all motors.

Safety Considerations

Tire pyrolysis generates combustible gases and operates at elevated temperatures and pressures. Safety features include:

• Oxygen exclusion: The burner's air supply is carefully metered to provide just enough oxygen for combustion without creating an explosion hazard. Reactor pressure is kept positive, preventing air ingress.
• Pressure relief: The [[tire-pyrolysis-plant-pressure-relief-valve|relief valve]] (2 bar setting) prevents overpressure. An [[tire-pyrolysis-plant-emergency-vent|emergency solenoid vent]] can rapidly depressurize the reactor if needed.
• Temperature control: The PLC continuously monitors temperature. If it approaches 650 °C (unsafe), the burner is automatically shut down.
• Fire suppression: A [[tire-pyrolysis-plant-fire-suppression|dry-powder or CO2 extinguisher system]] protects the burner area from potential ignition.

Products and Economics

From 5 tonnes of shredded tire input:

• Oil output: 1.9–2.1 tonnes (38–42% yield) → ~$100–150/tonne wholesale = $190–315
• Char output: 1.6–1.8 tonnes (32–36% yield) → ~$200–300/tonne = $320–540
• Gas: Recycled (net zero cost; actually reduces fuel consumption)
• Gross product value per batch: ~$510–855 (averaging $682)

Operating costs:

• Labor: 2–3 operators @ $20/hr = ~$200/batch
• Electricity: 45 kW × 2.5 hours = 112 kWh @ $0.12/kWh = ~$13
• Natural gas (supplemental, when recycled gas insufficient): ~$30/batch
• Cooling water: ~$10/batch
• Maintenance: ~$50/batch (depreciation and wear)

Total operating cost per batch: ~$300–400 Net profit per batch: ~$300–500 (assuming wholesale prices)

A facility running 8 batches per day (3 shifts) × 250 operating days/year = 2000 batches/year × $400 profit = $800,000 annual profit (very rough estimate; assumes no capital costs and typical market conditions).

Environmental Benefit

Compared to landfill disposal (占用land) or tire-derived fuel (TDF) incineration with air emissions:

• Tire pyrolysis recovers 100% of chemical energy as usable products (oil + char + gas).
• Emissions are significantly lower than incineration (no combustion particulates).
• Char is a value-added product (carbon black alternative) rather than waste.
• Oil can be refined into ultra-low-sulfur diesel or used as fuel oil, avoiding virgin crude oil extraction.

A 50 tonne/day facility (10 batches/day) processes 150,000 tonnes/year of scrap tires, preventing landfill disposal of that volume while recovering 57,000 tonnes of oil and 50,000 tonnes of char.

Maintenance

Daily: Check reactor rotation smooth and burner flame stable. Verify oil and char collection levels and drain as needed.

Weekly: Drain moisture from the [[tire-pyrolysis-plant-gas-compressor|burner blower]] air intake; check cooling-water for leaks and top up cooling-tower water loss.

Monthly: Inspect [[tire-pyrolysis-plant-heat-piping|heat-transfer piping]] for leaks. Check [[tire-pyrolysis-plant-refractory-lining|refractory bricks]] via borescope for cracks.

Quarterly: Change [[tire-pyrolysis-plant-heat-transfer-fluid|heat-transfer oil]] if it darkens or shows signs of degradation. Grease [[tire-pyrolysis-plant-rotation-motor|motor]] and [[tire-pyrolysis-plant-rotation-gearbox|gearbox]] bearings.

Annually: Full inspection of [[tire-pyrolysis-plant-reactor-shell|reactor vessel]] for corrosion (on water/cooling side). Refractory replacement typically required every 2–3 years (wear due to thermal cycling and abrasion).