Gasification + Fischer-Tropsch. Seven steps, one plant.
Below is our process flow diagram. Every step happens in the Zuriwo plant, from industrial waste going in to SAF and renewable diesel coming out. Click any step, or any part of the diagram, to see what happens there.
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Feedstock
We start with industrial waste from factories and recyclers.
- Clean and segregated
- Low moisture
- No metal, stones or other inert material
Preparation
The waste is shredded, dried and cleaned up, so the gasifier gets a steady, predictable feed.
- Shredding and screening
- Drying, if the waste is wet
- Magnetic separation of metal
Gasification
The waste is heated with a controlled amount of oxygen and steam, too little for it to burn fully. It breaks down into syngas, a gas made mostly of carbon monoxide (CO) and hydrogen (H₂).
- Main product: raw syngas (CO + H₂)
- Also: ash, removed from the bottom
Gas cleaning & conditioning
FT catalysts are easily poisoned, so the raw syngas is cleaned of dust, tar, sulphur and chlorine. Its hydrogen-to-carbon-monoxide ratio is then adjusted to suit the FT reactor.
- Cyclone and scrubbing remove dust and tar
- Sulphur and chlorine removed to protect the catalyst
- H₂:CO ratio set for FT synthesis
Fischer-Tropsch synthesis
In the FT reactor, the clean syngas passes over a catalyst that links the small CO and H₂ molecules into long hydrocarbon chains. The result is a mix of liquid hydrocarbons and wax, free of sulphur and aromatics, which goes straight on to upgrading.
- Output: FT liquids and wax
- By-product: water
- Tail gas used for plant heat and power
Upgrading
The FT liquids and wax are treated with hydrogen. Hydrocracking cuts the long wax molecules down to the jet-fuel and diesel range.
- Hydrocracking shortens the wax molecules
- Hydroisomerisation improves cold-weather flow
- Hydrotreating saturates the remaining olefins
Fractionation & certification
Distillation splits the upgraded product into naphtha, a jet-fuel cut and a diesel cut. The jet cut becomes SAF, which is certified to ASTM D7566 (the standard for SAF) before blending with regular jet fuel. The diesel cut becomes renewable diesel.
- Jet cut: SAF, blended with conventional jet fuel
- Diesel cut: renewable diesel
- Naphtha: by-product