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Dryer Drum Retrofits Improve Plant Performance

September 26, 2021

Dryer Drum Retrofits Improve Plant Performance

Categories: Asphalt Plants

They Improve Efficiency and Lower Operating Costs

Many asphalt producers are replacing old drying drums with newer, more advanced versions to upgrade existing equipment and reduce operating costs.

Such retrofits improve fuel efficiency and recycling capabilities – a huge cost saving for manufacturers. They also incorporate new components that reduce costly downtime. Dryers play a significant role in the financial and environmental performance of a plant. Optimal heat transfer, low heat losses and stable process temperatures are their most important functions.

Ammann drying drum retrofits are compatible with equipment from Ammann or other manufacturers. Ammann Dryers heat and dry raw materials of different compositions, material properties and moisture contents. They have exceptional wear resistance, are easy to maintain and highly efficient.

The Ammann RAH50 is a popular retrofit because it allows customers to work with recycled asphalt. These middle ring Dryers can seamlessly replace either existing Ammann drums or those supplied by another manufacturer.

Christian Westphal, Head of Machine Technology MTA Mischwerke SAW Schleswiger Asphaltsplitt-Werke GmbH & Co. KG, retrofitted a plant with an Ammann RAH50 drum. He explained how his new middle Dryer ring works compared to a conventional new mineral drum.


Mr. Westphal, were you aware of the advantages of the new RAH50 Dryer drum compared to the previous systems with middle ring feed?

I only knew the advantages of the RAH50 compared to other drum addition systems from conversations with sales representatives. At first, I was rather skeptical because of the promised high RAP addition rates (up to 45%).


Has your attitude changed after the past months with the system?

Yes, the promises have been kept regarding flexibility and RAP addition. The maintenance effort is, of course, slightly higher than with a pure new mineral drum, but it is lower than previously expected. Surprisingly, RAP caking is not a problem at all.


How flexible is the application of an RAH50 drum?

In addition to the standard cold feed, the RAH50 drum gives us the flexibility to switch to hot recycling. It is already worthwhile for us to use the RAH50 middle ring addition from batch sizes of 50 tonnes. Switching to hot recycling is problem-free, taking into account the overrun from the Dryer drum to the hot mineral silo. For permissible construction measures, RAPpercentages of up to 45% are possible for base layers via the middle ring addition. This enables us, in consultation with the client, to recycle large quantities – which of course offers enormous advantages in terms of costs.


What are the other advantages?

The addition of RAP to the RAH50 drum enables gentler heating compared to cold addition. When mixing the raw material with the RAP, we can run drum outlet temperatures of 160º C to 170 °C. This is gentle on all plant components and also saves fuel. The frequency converter installed in the drive motors also allows us to vary the dwell time of the new minerals and the RAP, which means that all types of aggregate are dried very effectively.


Is the system more profitable with the RAH50 compared to the use of a pure cold addition?

Yes, the system is absolutely more profitable due to the high volume of RAP that can be added.


Would you choose the RAH50 system again?

Yes, the system is very flexible in combination with a cold addition and allows high quantities of RAP to be added.


Dryer drum replacement

Asphalt production leaves its mark on your plant. With a retrofit, you can renew and protect important plant components. This extends the service life of the plant and makes operation more efficient.


Ammann drying drum

  • Highest flexibility due to variable rotation and discharge direction
  • Wall thicknesses up to 15 mm
  • Available with Amdurit wear protection and high-temperature steel
  • Low-wear and low-maintenance design with high material quality and easy-to-replace wearing parts
  • Optimised internals for a wide range of fuels
  • Frequency converter for energy-efficient operation


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