Clean performance.

The hot gas generator

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

Providing asphalt in the required quality and quantity at the right time is already a challenging task 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 indispensable.

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

Clean performance

Recycling drum using counterflow action with a hot gas generator

Exhaust gas flow
Recycling drum
Burner and hot gas generator
Further processing
Clever process solution

While the recycling material containing bitumen would “burn” with direct firing or undergo an adverse change to its properties, the hot gas generator heats it only indirectly, gently bringing it up to its optimum application temperature.

At the same time, the process reduces emissions – for example because the total carbons in the exhaust flow are largely burnt off.

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

The hot gas generator technology allows fresh asphaltic mixtures to consist of 100 % reclaimed asphalt.

The result – crucial advantages:
  • High recycling content of 100 %
  • Low emissions, TC < 50 mg/m³
  • Better energy balance of the plant
  • Lower strain on the filter unit
  • Reduced bitumen costs
  • More sustainable and more efficient asphalt production
  • Saves CO₂
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Systematic structure
Hot feed system

The main components of the hot feed system use coordinated processes:

> RAP chute (self-cleaning)
> Recycling drum
> Burner
> Hot gas generator
> 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 protection door. A large maintenance access in combination with the key transfer system ensures maximum safety and ease of maintenance.

High recycling input rates and low emissions can only be achieved with the counterflow action in the hot gas generator. The reason: With the hot gas generator technology, only a small quantity of TC can be generated because the recycling material is heated to 160 °C with high efficiency and has no contact with the burner flame. Degasification of bitumen is therefore minimised. Any generated TC concentrations are mostly returned to the hot gas generator with the circulating air and burned there.

Recycling drum

> Recycling material flow against the heat flow
> Longer active dwell time of the RAP material in the drum and gentle indirect heating
> Better heat transfer with optimised material veil (100 % closed material curtain) in the drum
> Homogeneous heating of the drum with a new generation of internal parts (patented)
> Less material accumulation/adhesions and self-cleaning effect

Extraction hood

> The extraction hood acts as a separator (fine particles)
> The exhaust flow is smoothed with the large extraction hood so that particles from the exhaust 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 stringent legal emissions limits (e.g. in Germany: guaranteed compliance with the limits of the TA-Luft regulation in continuous operation with appropriate measurements)
> Clever air flow on the plant: emissions from the mixer and the skip track can be added to the hot recycling system and burned.

Optimised energy balance

> The mineral does not have to be overheated
> Gentle on the material
> Gentle on the plant (no water hammer)
> Optimised energy balance – with a frequency-controlled, closed system for circulating and exhaust air, for example
> Low impact on the dedusting system (filter pockets) due to lower fine content from the recycling process
> Adjustable exhaust gas temperature level, just above the dew point
> Reduction of emissions which degasify during heating of the recycling material or additives at temperatures as low as 160 °C

Recipe generator

> System-relevant software expansion for dynamic generation of recipes with variable content of recycling material
> Advantage when using a high content of recycling material
> No interruption of production for changing the RAP feed rate
> No recipe change necessary
> Continuous asphalt quality

Easy maintenance and accessibility

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

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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BENNINGHOVEN technologies

Asphalt production, recycling systems, combustion technology, control systems and bitumen technology – with BENNINGHOVEN technologies, every customer can find the right solution for their location, according to the specific requirements and conditions.

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