With models ranging in production from 140 tons per hour to 500 tons per hour, Aesco Madsen’s CFM Series of counterflow Drum Mixers are designed to meet the performance output required for nearly any application. The technology in every CFM series counterflow drum mixer utilizes a long nose burner that is pointed upstream, against (counter to) the flow of the virgin aggregate entering the drum.
The Counterflow Process
As virgin aggregate first enters the drum, it passes through the drying zone where the material is brought to temperature and any moisture is removed. This is accomplished by a series of heavy veiling grid flights, which lift the material up, then evenly spread it through the burner’s heat stream.
The material then continues to travel towards the burner to the combustion zone. The combustion flights lining this section of the counterflow drum perform two crucial functions. First, they serve as a heat shield, protecting the shell of the drum from overheating. Second, they prevent the aggregate from falling through the burner flame and causing improper combustion.
Lastly, the virgin material travels behind the burner flame into the mixing zone where liquid asphalt, RAP (recycled asphalt pavement), fines, and additives are blended into the mix. It is in this mixing chamber that the benefits of counterflow technology are truly realized. Conducting the mix process away from the hot gases and burner flame allows the CFM series counterflow drum mixer to eliminate the environmentally harmful hydrocarbon (blue smoke) emissions seen in more traditional plant technology. Additionally, this counterflow system allows for a significantly higher amount of RAP to be utilized, drastically reducing overall operating costs. With five separate models of CFM series counterflow drum mixers available, Aesco Madsen is able to offer this versatile system to meet any need, matching the specific production requirements of each and every customer.
The Perfect Veil Through Custom Flights and VF Drives
It is extremely important to have the right veil of material within the drum. A veil that is too thick will impede the heat flowing into the baghouse, causing moisture within the baghouse to condense. This unwanted moisture will result in dust caking to the bags, lowering baghouse efficiency and overall plant production. Alternatively, too thin of a veil will result in an excess of heat entering the baghouse creating a fire risk. The operator is then forced to trim down the burner, also lowering overall plant production.
While several factors contribute to the optimal veil produced by the CFM Series Counterflow Drum Mixer, there are two crucially notable components that work in unison with one another and should be highlighted.
First is Aesco Madsen’s custom SJ2 Bolt-in-Flights. These SJ2 flights were developed by industry experts within the company based off of decades of experience and careful research into the physics behind producing the perfect veil. Exclusive to Aesco Madsen drum mixers and available in a variety of angles for an added dimension of adaptability; the SJ2 Bolt-in-Flights have been central to the success and reputation that the CFM series counterflow drum mixers have received over the years.
The second major component responsible for the sought after veil seen in the CFM Series counterflow drum mixers are their variable frequency drives used to control the rotation of the drum. With this innovative feature the plant operator is given complete control over the drum mixers rotational speed through the simple turn of a dial. Thus, the rotation of the drum can be fine-tuned in order to pinpoint the speed where the drums SJ2 grid flights produce the perfect veil for any given production requirements.
Efficiency, production range, and an optimally mixed final product are all linked to the veil produced by the drum mixer. When one understands that the veil influences almost every aspect of an asphalt plant, it can be easy to see why a well-distributed veil is so important. It is for this reason that Aesco Madsen has focused so much effort on, and succeeded in, producing the perfect veil as evidenced through their CFM counterflow drum mixers.
CFM Series Counterflow Dryer Model Specifications
All CFM series counterflow drum mixers come standard with heavy duty I-beam welded construction. Durable crossbeams support the trunnion assemblies and provide additional structural integrity to the drum frame. These trunnions, which propel the drums rotation by way of forged, one-piece, solid steel drum tires mounted to the drum shell, are supported by Heavy-duty pillow block bearings. On either side of the drum tire are durable thrust idlers to maintain the drums uphill/downhill alignment as it rotates. Preventing the drum tires from shifting off of their trunnions is crucial in avoiding both uneven wear of the trunnions and harmful grooves from forming.
CFM Series Standard Features
- SJ2 bolt-in flights for easy replacement and veil adjustment
- Built with heavy duty I-Beam welded construction
- Counterflow technology for higher RAP usage and lower hydrocarbon emission
- High efficiency burners
- Slinger belt with reversing capabilities for easy calibration
- Compatible with all warm mix and additive systems
To provide industry-leading quality while remaining conscious of their customer’s budgets, Aesco Madsen designed their base model CFM drum mixers to exceed the production and durability standards of most in the field. Multiple upgrade options are, however, available for those who seek the added efficiency and long-term cost savings that accompany them.
CFM Series Available Upgrades
- Insulation wrapped shell within a durable aluminum covering to lower both heat loss and long-term burner fuel costs
- Hydraulic lift for quick, efficient set-up and slope adjustment
- Stationary, Relocatable, or Portable configurations
- High efficiency burner capable of utilizing any type of fuel oil, natural gas, reclaimed oil, or propane
- Adjustable drum rotation speed by way of a variable frequency drive
- Warm Mix and Anti-Strip additive systems
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