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Exhaust air purification and energy recovery – reducing emissions, securing energy

oxytec systems for integrated exhaust air purification with usable heat for industrial processes

Industrial processes generate large quantities of exhaust air – often warm, humid, polluted, and odorous. The challenge: the exhaust air must be purified, but at the same time valuable heat is lost. The solution: combined systems for exhaust air purification and energy recovery, such as those offered by oxytec. These systems reduce emissions in accordance with TA Luft (German Technical Instructions on Air Quality Control) and reduce energy requirements by recycling process heat.

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Typical sources of warm, contaminated exhaust air

emission source Typical pollutants Special features / Temperature
Frying and baking processes Fats, aerosols, VOCs, odors 80–150 °C, grease-laden, continuous
Painting and drying lines Solvents (VOCs), fine dust, heat 60–140 °C, solvent-laden, sensitive
Textile and paper finishing Vapors, VOCs, organic additives 70–130 °C, humid, temperature-stable
Cleaning and rinsing processes Aerosols, water vapor, cleaning agents 40–90 °C, high moisture content
Heat treatment/pressing Formaldehyde, resins, VOCs, heat 100–160 °C, sticky, strong odor

Why exhaust air purification with heat recovery makes economic sense

Reduction of energy costs through recycling of process heat

Compliance with legal emission limits (VOC, odor, particles)

No additional energy consumption for cleaning as with thermal post-combustion

Short payback period through energy savings

Eligible for funding under energy efficiency and climate protection programs

Legal requirements

TA Luft 2021

  • Limit values for VOC, formaldehyde, ammonia, odor
  • Obligation to use energy-efficient exhaust air technology

4th BImSchV / BImSchG

  • Approval requirement depending on volume flow and solvent consumption
  • VOC reduction often relevant for regulatory purposes and mandatory
  • GIRL (Odor Emission Guideline)
  • Important in proximity to residential areas
  • Assessment based on odor hours and dispersion models

EEWärmeG, EED, GEG

  • Requirements for primary energy savings and process heat recovery

Eligible for funding via

  • BAFA (energy efficiency, process heat)
  • KfW (climate protection investments)
  • State programs (e.g., environmental technology, decarbonization)

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Why combine exhaust air purification with energy recovery?

Reduction of energy costs through recycling of process heat

Compliance with legal emission limits (VOC, odor, particles)

No additional energy consumption for cleaning as with thermal post-combustion

Short payback period through energy savings

Eligible for funding under energy efficiency and climate protection programs

oxytec solutions for combined exhaust air treatment

UV ozone systems for VOC and odor removal

Reliably decomposes VOCs, odors, grease, and resin compounds

No open flame → no heat destruction

Works at high temperatures and humidity levels

Modularly scalable for small businesses to industrial plants

Aerosol separator for air contaminated with particles and grease

Reliably removes grease, oil mist, and fine dust

Protects heat exchangers from clogging and loss of efficiency

Stainless steel versions available for aggressive exhaust air

Heat recovery systems (HRS)

Plate or shell-and-tube heat exchangers for exhaust air flows

Use of recovered heat, e.g., for:

  • Preheating fresh air
  • Hot water preparation
  • Process energy

Combination with UV ozone and aerosol technology for clean energy

Condoheat – process-compatible heat generation

oxytec subsidiary solution for intelligent process heat utilization

Can be combined with recovered exhaust air energy

Significantly reduces the heating requirements of conventional systems

Typical areas of application

  • Frying and deep-frying lines in the food industry
  • Painting systems and coating processes
  • Wood and furniture production with hot pressing
  • Paper finishing and textile dryers
  • Cleaning and CIP systems with high water consumption

Your advantages with oxytec systems

Exhaust air purification and heat recovery in one system
Low maintenance, chemical-free, no thermal afterburning
Recovery of usable heat for production or HVAC systems
Resistant to grease, moisture, VOCs, and temperature
Approval-secure, eligible for subsidies, future-proof

FAQ – Frequently Asked Questions

Which types of exhaust air are suitable for heat recovery systems?

Particularly suitable are:

  • Warm exhaust air flows from approx. 60°C
  • Processes with continuous or regularly recurring heat loads
  • Exhaust air with moderate or treatable VOC and grease content
  • Typical examples: Baking lines, painting systems, textile or paper finishing, cleaning processes

Can I use VOC-contaminated exhaust air directly for heat recovery?

Only to a limited extent. VOCs and aerosols must be removed or neutralized before heat recovery, as they:

  • Contaminate or clog heat exchangers
  • Can be explosive at high temperatures

Oxytec therefore relies on upstream UV ozone purification and aerosol separators to ensure that heat recovery systems operate efficiently in the long term.

How much energy can typically be recovered?

Depending on the process, up to 70% of the exhaust air heat can be recovered. Influencing factors:

  • Temperature and volume flow of the exhaust air
  • Heat exchanger surface area and type (plates, tube bundles, etc.)
  • Pre-cleaning of the exhaust air

The potential is particularly high in continuous processes with an exhaust air temperature of >80°C.

What happens to the recovered heat?

It can be used for:

  • Fresh air preheating (supply air systems)
  • Hot water preparation for cleaning or building heating
  • Process heat in connected production stages

With oxytec Condoheat, heat flows can be specifically recirculated and even combined with other energy sources.

Are UV ozone systems compatible with heat recovery?

Yes – they are particularly suitable because:

  • They operate at moderate temperatures (no heat input)
  • They eliminate VOCs and odors without additional energy input
  • Downstream heat exchangers are not contaminated by chemical residues

Cleaning takes place before recovery – this protects and increases the yield.

What legal requirements apply to the combination of exhaust air purification and heat recovery?

The following are essential:

  • TA Luft 2021: Limit values for VOCs, formaldehyde, odors → Cleaning necessary
  • GIRL: Limit values for odor emissions in sensitive neighborhoods
  • EEWärmeG / GEG / EED: Promotion of energy efficiency through heat recovery
  • BImSchG: Approval requirement for larger plants using solvents or energy

A well-documented WRG cleaning combination can be positively evaluated and promoted here.

What funding opportunities are available for such systems?

The following are eligible for funding:

  • VOC reduction systems (UV, activated carbon, separators)
  • Heat recovery systems as a contribution to energy savings
  • Investments to comply with TA Luft / EED requirements
  • Programs:
    • BAFA (Module 4 – Cross-sectional technologies)
    • KfW climate subsidy
    • State programs for environmental technology & efficiency

Oxytec assists you with subsidy advice and application.

How much maintenance is required for such combined systems?

Very low:

  • UV lamps: Replacement after 8,000–10,000 hours
  • Aerosol separators: Clean every 1–3 months, depending on load
  • Heat exchanger: Virtually maintenance-free with upstream cleaning
  • Optional: Remote monitoring and maintenance contract by Oxytec