Comprehensive Guide to Setting Up Pyrolysis Equipment
Pyrolysis turns waste into energy-rich products through oxygen-free heating. The process demands precise equipment choices and disciplined setup to deliver consistent yields.
Operators who rush procurement or skip calibration steps face tar clogging, uneven heating, and catastrophic refractory failure within weeks. A methodical approach prevents these losses and keeps the plant cash-positive from day one.
Core Equipment Components and Their Functions
Reactor Types and Selection Criteria
Rotary drums dominate tire recycling because their slow rotation tumbles feedstock, exposing every rubber chip to the same radiant heat. A 3 m × 12 m carbon-steel drum with 15 mm wall thickness handles 3 t day⁻¹ of shredded tires and lasts 8,000 h before the first shell replacement.
Horizontal fixed-bed reactors suit agricultural residues; they cost 30 % less than rotary units and eliminate rotating seals that leak syngas. However, char removal is manual, so plan a 30 min shutdown every 4 h or install twin beds in parallel.
Auger reactors shine for plastics: a 200 mm Ø screw with variable pitch compresses melting PET, squeezing out air pockets and raising bulk density by 25 %. This self-cleaning action cuts downtime from polymer crusts to near zero.
Heat Source and Transfer Design
Indirect flame tubes raise reactor wall temperature to 550 °C while keeping flue gas separate from product gas. Position two 150 kW dual-fuel burners at 120° intervals to avoid hot spots that warp the shell.
Electric resistive coils wrapped around a 50 mm ceramic fiber blanket give ±2 °C accuracy for small pilot units. Budget 1.2 kWh per kg of wood chips; tie coils to a PID loop that reads skin thermocouples every 5 s.
Heat carrier recirculation—sand or steel shot—transfers energy faster than conduction alone. A 1 mm sand film at 600 °C can pyrolyze sewage sludge in 3 s, cutting reactor volume by 40 % compared with indirect heating.
Site Preparation and Infrastructure
Concrete Foundations and Reactor Anchorage
Cast a 400 mm reinforced slab with 16 mm rebar on 150 mm centers; pyrolysis reactors cycle between 350 °C and 550 °C, creating thermal growth of 4 mm m⁻¹. Anchor bolts must sit in oval sleeves, not tight holes, to let the shell expand without cracking grout.
Vibration from rotating drums travels through the frame; isolate the drive motor on neoprene pads rated for 0.5 g lateral acceleration. One 5 mm pad under a 30 kW gearbox reduces structural noise by 12 dB and prevents bolt loosening.
Utilities Routing and Safety Perimeters
Run 4 in Schedule 40 carbon-steel pipe for cooling water; maintain 2 m s⁻¹ velocity to keep heat exchanger tubes below 45 °C. Return lines need 1 % slope back to the cooling tower to avoid syphon breaks that starve the condenser.
Install a 2 m gravel berm around the reactor pit; if 200 L of hot pyrolysis oil spills, the berm contains 90 % of the volume and keeps flames away from cable trays. Mark a 5 m exclusion zone with yellow paint and lock-out sensors that trip feed conveyors when breached.
Feedstock Handling and Pretreatment
Size Reduction and Drying Lines
Hammer mills with 25 mm grates shrink tire chips to 10 mm; smaller particles heat evenly and raise oil yield from 38 % to 46 %. Swap hammers every 500 t—worn faces smear rubber, creating balls that block rotary valve pockets.
Moisture above 10 % steals latent heat and drops reactor temperature. A triple-pass rotary dryer at 180 °C reduces 1 t of green wood chips from 50 % to 8 % moisture in 20 min, burning 28 m³ of syngas—energy you recover later.
Metal and Contaminant Removal
Over-belt magnets pulling 900 G extract steel beads from tire shred; missing 1 % of wire raises ash content in char from 12 % to 22 %, slashing its carbon black value. Add a second magnet 2 m downstream to catch wires aligned parallel to the first field.
Air knives blow lightweight plastic film away from denser PET flakes. Adjust nozzle pressure to 0.3 bar; higher pressure lifts good resin, cutting yield by 5 %.
Startup Sequence and Temperature Profiling
Initial Heat-Up Protocol
Ramp the reactor at 30 °C h⁻¹ until the outer shell reaches 120 °C; hold for 2 h to bake refractory moisture. Skipping this step causes steam spalling that peels 10 mm of castable within days.
Inject 50 kg of dry wood pellets to create a char bed; this bed absorbs tars during later feeds and prevents liquid film formation on walls. Monitor CO/CO₂ ratio: a drop below 0.5 signals incomplete char gasification—raise primary air by 5 %.
Transition from Startup to Production
Begin steady feed at 20 % design rate; every 30 min raise the rate by 10 % while watching exit gas temperature. If it climbs above 450 °C, slow the feed—hot gas means incomplete heat transfer and impending coking.
Record motor amperage on the auger; a 15 % spike indicates bridging. Stop feed, pulse nitrogen at 2 bar for 10 s, then resume at 5 % lower rate.
Condensation and Oil Recovery
Multi-Stage Condenser Layout
First shell-and-tube stage at 200 °C knocks out heavy aromatics; use 316 L tubes to resist phenol corrosion. A single 10 m² unit recovers 70 % of total liquid from tire pyrolysis gas.
Second stage chilled to 60 °C by a 5 kW glycol loop captures light aromatics. Insulate pipes with 50 mm Armaflex; every 1 °C rise loses 0.3 % of naphtha-range product.
Electrostatic precipitator at 25 kV removes 5 µm aerosols that pass impingers. Clean collector plates weekly; tar build-up thicker than 2 mm arcs and trips the power supply.
Storage and Stabilization
Transfer oil into 10 t tanks with internal floating roofs; this cuts breathing losses from 1 % to 0.2 % per day. Nit blanketing at 50 mbar stops polymerization that would raise viscosity by 30 cP within a week.
Add 200 ppm BHT antioxidant during pumping; without it, olefins form gums that clog engine injectors after 30 days. Mix with a side-stream loop to ensure uniform dispersion.
Non-Condensable Gas Management
Cleaning and Compression
Pass gas through a fiberglass coalescer rated 99 % at 1 µm to remove oil mist. Compressor valves foul in 200 h if mist exceeds 50 mg m⁻³.
Use a liquid-ring compressor with water seal; it handles occasional tar carry-over without damage. Maintain seal water at pH 6; alkalinity above pH 8 precipitates phenolates that score the impeller.
Energy Recovery Routing
Route 60 % of cleaned gas to dual-fuel burners; calorific value at 11 MJ m⁻³ replaces 18 L h⁻¹ of diesel. Install a 5 kW blower with variable speed to keep gas pressure 20 mbar above burner demand.
Send surplus gas to a 50 kW genset after activated-carbon guard beds. H₂S above 50 ppm pits copper windings; replace carbon when breakthrough smells of rotten eggs.
Char Discharge and Upgrading
Continuous Removal Systems
Double-dump valves isolate the reactor while allowing char outflow; cycle every 2 min to keep level constant. Replace neoprene seals every 1,000 h—brittle seals leak air, causing char ignition that hits 800 °C and warps the grate.
Cool screw conveyors with jacket water at 90 °C; hotter water avoids condensation that would wet char and clog flights. A 200 mm Ø screw moving 0.5 t h⁻¹ needs 5 m of length to drop temperature below 60 °C.
Post-Treatment for Added Value
Activate char in a second 700 °C zone with 0.5 kg h⁻¹ steam; surface area jumps from 80 m² g⁻¹ to 450 m² g⁻¹, raising sale price from $0.20 kg⁻¹ to $1.10 kg⁻¹. Residence time of 15 min is enough; longer yields marginal gains and wastes fuel.
Pelletize fine char with 5 % molasses binder; pellets handle better and command $50 t⁻¹ premium over powder. Use a 40 MPa ring-die press; lower pressure crumbles during transport.
Emission Control and Regulatory Compliance
Particulate and VOC Abatement
Baghouse with 550 g m⁻² PTFE filters keeps stack dust below 5 mg m⁻³. Pulse cleaning at 5 bar every 60 s maintains <1,000 Pa ΔP; higher ΔP halves fan life.
Regenerative thermal oxidizer at 850 °C destroys 99 % of VOCs but consumes 8 % of total gas yield. Pre-heat the RTO with pyrolysis gas during startup to avoid diesel use.
Continuous Emission Monitoring
Install FTIR for benzene; permit limit is 5 mg m⁻³. Calibrate weekly with 100 ppm propylene span gas; drift beyond 2 % triggers sensor replacement.
Log data every minute to a cloud dashboard; regulators accept encrypted PDF exports. Keep 5 years of records—inspectors often request random 30-day windows.
Automation and Control Philosophy
Sensor Placement Strategy
Mount thermocouples at 25 %, 50 %, and 75 % of reactor length; temperature gradients above 30 °C indicate channeling. Use Type K sheathed probes; bare wires corrode in 300 h.
Pressure sensors on both reactor ends detect blockages; a 50 mbar rise within 5 min triggers feed shutdown. Flush impulse lines weekly with nitrogen to keep tar out.
PLC Programming Tips
Program a cascading PID loop: outer loop controls wall temperature, inner loop modulates burner air. Tune the outer loop 4× slower to avoid oscillation.
Create an alarm matrix; assign every tag two levels: warning at 80 % limit, trip at 100 %. Log operator acknowledgments with timestamps for audits.
Maintenance Scheduling and Spare Parts
High-Wear Items Checklist
Keep four reactor seals, two burner nozzles, and one gearbox in stock; lead times exceed 8 weeks. Track runtime hours with an hourly meter glued to the HMI.
Change Shell-side gasket every 2,000 h; choose graphite-filled spiral-wound type rated 550 °C. Reuse old bolts only after ultrasonic crack check.
Predictive Maintenance Tools
Vibration sensor on the drum drive shows bearing wear; trend acceleration RMS. A 3× rise over baseline predicts failure within 10 days—order parts immediately.
Oil analysis every 500 h reveals seal degradation by sudden silicon increase. Switch to high-temperature fluorocarbon seals if silicon exceeds 50 ppm.
Cost Control and ROI Optimization
Energy Integration Tactics
Pre-heat feedstock with 120 °C flue gas in a jacketed screw; this saves 0.4 MJ kg⁻¹, cutting burner duty by 8 %. Insulate the jacket with 25 mm calcium silicate to keep surface below 50 °C.
Recycle hot condensate at 90 °C back to the boiler; each liter saves 0.38 MJ. A simple plate exchanger raises makeup water from 20 °C to 75 °C.
Revenue Diversification
Sell heavy oil to asphalt plants after cut-back with 15 % flux oil; they pay 80 % of bunker fuel price. Filter through 100 µm mesh to remove char fines that block spray nozzles.
Offer carbon credits for avoided open burning; one ton of diverted tires equals 0.9 t CO₂e. Register under VCS and sell at $10 t⁻¹—enough to add 4 % to plant margin.