Thermal oxidisers (also called incinerators or thermox) destroy VOCs, HAPs and odorous compounds by raising the contaminated air to combustion temperature (760–1100°C, residence time 0.5–1 second), breaking hydrocarbon bonds down to CO2 and water vapour. Destruction efficiency 95–99.9% depending on duty.
Choose thermal oxidation when:
- VOC concentrations are too high for carbon adsorption to be economic
- The waste stream contains a mix of compounds carbon can’t handle
- Heat recovery offsets the fuel cost (recuperative or regenerative designs)
- Halogenated VOCs are absent, or downstream acid-gas scrubbing is acceptable
Choose against thermal oxidation when:
- Low-concentration / dilute streams (carbon or biofilter cheaper)
- High halogen content without scrubber tail-end
- NOx formation at high temp is a problem for the licence
- The duty is intermittent (start-up fuel cost dominant)
Frequently asked questions
What does a thermal oxidiser do?
It destroys VOCs, solvents, hazardous air pollutants (HAPs) and odorous organics by oxidising them to carbon dioxide and water vapour at high temperature — 95–99.9% destruction is achievable.
Direct-fired vs recuperative vs RTO vs catalytic — what is the difference?
Direct-fired is the simplest; recuperative and regenerative (RTO) add heat recovery (RTO highest, best for high-flow, dilute VOC streams); catalytic runs much cooler using a catalyst.
How hot does a thermal oxidiser run?
Typically 760–1100 °C for thermal types; catalytic systems operate around 320–450 °C with a catalyst.
What destruction efficiency can I expect?
95–99.9% destruction removal efficiency when temperature, residence time and mixing are matched to the compounds present — guaranteed against your measured conditions.
Can I recover the heat?
Yes — recuperative and regenerative (RTO) designs recover roughly 50–97% of the thermal energy to cut fuel use.
When is a catalytic oxidiser the wrong choice?
When the gas carries catalyst poisons — silicones, phosphorus, halogens or heavy metals — without protection, which shortens catalyst life.
Thermal oxidiser vs carbon adsorption vs scrubber — which do I need?
Oxidisers destroy organics; carbon adsorbs and can recover them; scrubbers absorb soluble gases or particulate. It depends on the pollutant, its concentration and whether recovery has value.
Do you guarantee performance?
Yes — process guarantees are written against your measured inlet conditions and target outlet limits, not catalogue numbers.
Thermal Oxidiser Types
Direct-fired oxidiser — simplest design, single combustion chamber, no heat recovery. Lowest capital cost, highest fuel burn. 760–870°C typical. Best for streams with high VOC concentrations where the VOCs contribute to combustion fuel.
Recuperative oxidiser — adds an air-to-air heat exchanger to preheat inlet air with the hot exhaust. 60–70% thermal recovery. Lower fuel cost than direct-fired, larger footprint. Good for moderate VOC streams.
Regenerative thermal oxidiser (RTO) — ceramic heat-sink beds switch between heating and cooling cycles. 90–95% thermal recovery. Highest capital cost, lowest operating cost — the dominant choice for industrial paint booths, printing, chemical reactor vents and pharma fermenters. 815–980°C operating.
Catalytic oxidiser (CatOx) — Pt or Pd catalyst on a honeycomb support lowers the operating temperature to 320–450°C. Sharply lower fuel use vs thermal, but catalyst is poisoned by halogens, heavy metals, sulphur and silicones. Best suited to clean VOC streams from well-characterised processes.
Common applications: paint booths, printing presses, chemical reactor vents, pharma fermenter vents, semiconductor abatement, food processing odour control.
Design limits to engineer against: NOx generation at high temp (especially RTO), acid gases from halogenated VOCs (HCl, HF, HBr — require downstream scrubbing), catalyst poisoning on CatOx. We size the package against your VOC composition, target destruction efficiency, available utilities (natural gas, LPG, process fuel), and licence-driven outlet limits.
Need more information? Contact our team for more specialised advice.