Circtec Ltd required a detailed assessment of "Thermal Oxidiser Design for a Tyre Pyrolysis Plant" in 2024. The work brought together computational fluid dynamics (CFD) and process modelling and the project information supplied for this process and manufacturing application. The central objective was to connect local flow, thermal, transport or process behaviour with system-level performance, risk and design decisions that the client could implement.

End-of-life tyre pyrolysis produces syngas streams that require complete combustion to meet stringent EU waste-incineration standards. The aim of this project was to design and validate an optimised thermal oxidiser capable of treating these off-gases at ≥850 °C for at least 2 s, thereby preventing release of incomplete combustion products. Using high-fidelity CFD combustion modelling, combined with Aspen Plus process simulations, our team evaluated chamber geometries and operating conditions. Design improvements such as reoriented burners, internal baffles, and an extended outlet duct were introduced to enhance mixing and eliminate cold pockets. These modifications ensured almost 100% compliance with regulatory time-at-temperature requirements. Circtec subsequently adopted our recommended configuration, constructing and operating the enhanced oxidiser. This marks a successful example of ManchesterCFD providing end-to-end support from computational analysis through to validated real-world implementation, helping the client deliver sustainable waste-to-resource technology at industrial scale.

The methodology centred on a high-fidelity reacting-flow CFD model of the thermal oxidiser, complemented by Aspen Plus process calculations. The representation retained the burners, combustion chamber, baffles and outlet duct that govern mixing, flame products, cold pockets and gas residence time. Boundary and operating conditions covered the tyre-pyrolysis off-gas composition and flow, burner orientation, chamber geometry and operating conditions relevant to the regulatory duty, with material, fluid and equipment properties assigned from the available design information. Resolution was concentrated in regions where steep velocity, thermal, concentration or phase gradients were expected, while the overall model remained efficient enough to compare several credible configurations. This balance allowed system-level performance to be linked to the local mechanisms responsible for it.

The assessment compared burner reorientation, baffle placement and outlet-duct extension. Performance was judged using temperature, mixing, oxygen and combustion-product distribution, residence time above 850 degrees C, cold-zone volume, pressure loss and compliance with the two-second criterion. Results were reviewed through quantitative summaries and engineering visualisations, such as contours, vectors, streamlines, sections and time histories, selected to suit the physics. Important assumptions and operating uncertainties were considered so that the recommendations relied on repeatable comparative trends rather than a single nominal case.

For Circtec Ltd, the principal value was an implemented oxidiser design that met the time-at-temperature requirement and supported cleaner industrial operation. The final evidence linked each recommendation to the relevant model or process output, making it suitable for internal design reviews, supplier or contractor discussions and, where applicable, planning, safety or regulatory dialogue. The work also created a reusable baseline that can be updated as geometry, operating data or test results become available, reducing the cost and risk of later design iterations.