Clean performance.

The hot gas generator
from BENNINGHOVEN

The leading, patented recycling technology from BENNINGHOVEN allows plant owners to produce asphaltic mixture from 100% reclaimed asphalt. At the same time, the asphalt mixing plant meets the stringent official limits for air quality control, including German TA-Luft regulations.

Supplying asphalt in the required quality and quantity at the right time is already a challenge that requires perfectly coordinated plant components. When maximum recycling content in asphalt production with minimum emissions are added to the equation, the BENNINGHOVEN hot gas generator becomes truly indispensable.

BENNINGHOVEN Offers integration of the hot feed system as a new system or as a Retrofit solution for existing asphalt mixing plants.

Clean performance

Counterflow recycling drum with hot gas generator

Exhaust gas routing
Recycling drum
Burner and hot gas generator
Further processing
Well-designed process solution

While direct firing would tend to “burn” the recycled material coated with bitumen or at least impair its properties, the hot gas generator simply heats it indirectly and therefore raises it gently to the optimum processing temperature.

And the process also cuts emissions – by ensuring the total carbon content in the exhaust gas flow is largely combusted at the same time, for example.

The recycling material is heated to the optimum processing temperature of 160 °C. Emissions are kept within the standard range and the bitumen contained in the material is not combusted.

Hot gas generator technology means that fresh asphaltic mixture can be made from up to 100% recycled asphalt.

This results in a number of key advantages:
  • High recycled material feed rate of 100%
  • Low emissions, TC <50 mg/ m³
  • Improved plant energy footprint
  • Relieves loads placed on filter unit
  • Lower costs for bitumen
  • More sustainable and more efficient asphalt production
  • Cuts CO₂ emissions
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Systematic structure
Hot feed system

The main components of the hot feed system are coordinated to optimize the process.

> RAP chute (self-cleaning)
> Recycling drum
> Burner
> Hot gas generator
> Extraction > Extraction hood
> Transitions/slide valves are heated – preventing adhesions at transition areas

Hot gas generator

The hot gas generator essentially consists of a large cylindrical body. The opening for the burner on the face side is equipped with a pneumatically actuated heat shield door. A large maintenance access in combination with the key transfer system ensures maximum safety and ease of maintenance.

High recycling rates with low emissions can only be achieved by means of the countercurrent flow in the hot gas generator. Why? With hot gas generator technology, only a small quantity of total carbon (TC) can be generated because the recycling material is heated to 160 °C with high efficiency and has no contact with the burner flame. Bitumen outgassing is therefore minimized. Any concentration of TC generated is mostly returned by means of the circulating air to the hot gas generator, where it is then combusted.

Recycling drum

> Recycling material flows counter to the flow of heat
> Longer active dwell time of the RAP material in the drum and gentle indirect heating
> Better heat transfer with optimized material veil (100% closed material curtain) in the drum
> Homogeneous heating of the drum with new generation of internal drum parts (patented)
> Fewer material accumulations/adhesions and self-cleaning effect

Extraction hood

> The extraction hood acts as a separator (fine particles)
> The exhaust flow can be calmed with the large extraction hood so that particles from the exhaust gas flow can settle
> High level of separation so that fine particles cannot enter the exhaust gas channels but rather settle in the collection hull (no risk of the circulating air and exhaust air pipes clogging)

Ideal for users and the environment
Low emissions

> Compliance with tough laws on emissions (e.g. in Germany: guaranteed compliance with the limits of the TA-Luft regulation in continuous operation with appropriate measurements
> Well-designed plant air flow: emissions from the mixer and the skip track can be routed to the hot recycling system and burned to produce thermal energy.

Energetic optimization

> Mineral does not have to be overheated
> Gentle on the material
> Gentle on the plant (no hydraulic shocks)
> Energy-optimized, e.g. with a frequency-controlled, closed system for circulating air and exhaust air
> Lower load on the dedusting system (filter bags) due to lower fine content from the recycling process
> Adjustable exhaust gas temperature level, just above the dew point
> Reductions in the emissions that can outgas at less than 160 °C during heating of recycled material or aggregates

Recipe generator

> System-relevant software expansion for dynamic generation of recipes with variable recycling content
> Beneficial when running high recycled material feed rates
> No production downtime when changing the RAP feed rate
> No recipe change necessary
> Consistent asphalt quality

Simple maintenance and accessibility

> Large, ergonomic maintenance access points, service, and inspection openings
> Movable burner for burner head inspection
> Partial replacement of segments of the RAP chute including ceramic coating
> Fixed anchor points for abseiling
> Extraction hood with working platform options
> Key transfer system for increased work safety

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Sustainability by Benninghoven

Working more efficiently with sustainable and economical technologies is the challenge of today and tomorrow. Benninghoven offers a variety of innovative solutions for increasing sustainability in asphalt production.

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