Creating Value

Features - Plastics

Absolute Combustion International’s plastic extruder recycles soft plastics into building materials.

March 11, 2013

Eliminating low-density polyethylene (LDPE) from the waste stream and doing so in a manner that is energy efficient and environmentally safe is a concept that many material recovery facilities (MRFs) may only dream about. But one company in Alberta, Canada, has developed technology that is doing that very thing.

Absolute Combustion International (ACI), based in Leduc, Alberta, has developed a plastic extruder that it says can be used to recycle LDPE. The Absolute Extreme Burner was designed to produce heat without flame, creating what the company says is a consistent and controlled heat source ideal for working with low-density plastics.

According to Robindra Mohar, ACI vice president of business development, “The optimum situation [for recycling in the burner] is when the plastics have been streamed to allow for the same type of plastic to go through the process at one time. In our experience, we have found that these various plastics are often combined (mixed) and, when put through the recycling process, you must be very careful not to overheat the plastics that have a lower flash point.”

The LDPE recycled through the burner is used in building materials, such as decking, parking curbs, fence posts and plastic lumber. “To handle and create value for soft plastics, we can utilize the soft plastic in a multitude of ways,” says Mohar. The hard material that comes out of the burner can make up 20 percent or more of the content in these end products, he adds.

Seeing Results
One of the differentiating characteristics of the Absolute Extreme Burner is its ability to run entirely on natural gas or propane or on a combination of electricity and natural gas. This allows for what the company says is an equal distribution of heat and reduced costs compared with running entirely on electricity.

In 2009, the company had an opportunity to demonstrate this ability in the city of Medicine Hat, Alberta. The city of approximately 61,000 is nicknamed the Gas City for the large natural gas field that exists within it.

Rather than replace electric coils on a 20-plus-year-old burner, Medicine Hat approached ACI to retrofit the burner at its waste and recycling facility.

“Within two weeks, we had a conceptual drawing of what we believed might work and successfully implemented the solution within 90 days,” says Mohar.

He says most soft plastic ends up in a landfill. “The landfills have no economic way to recycle the soft plastics, and they end up staying in the landfill or being shipped to another jurisdiction or country, such as China.”

A major contributor to the landfill disposal of LDPE is the agricultural industry because of what Mohar describes as “the prolific single use of plastic silage bags.” He says it is a worldwide issue. “There is no penalty currently issued to farmers for the one-time use and throw away of these bags,” he says.

Because farmers aren’t required to dispose of these silage bags properly or to recycle them, Mohar says, in many areas of the world, they simply dump the bags into a hole.

During field tests conducted in Medicine Hat, Mohar says ACI was able to run a 300-foot silage bag through its machine at one time and reduce its size to a few pallets.

So what was the driver behind the development of the Absolute Extreme Burner? ACI CEO Darsell Karringten says he was motivated by ensuring a better world is left for his grandson. His idea was to invent and develop the burner with hopes that it would help propel a healthier, sustainable planet.

“Our philosophy is environmental stewardship. To be successful, ACI is looking to find a way to turn unwanted, nonviable plastics into value-added products,” explains Mohar. “ACI is committed to continually researching and developing technological innovations. We will seek to push the limits of what can be accomplished in the recycling world as well as pursue other verticals that can benefit from the low emissions maximum efficiency that our burner provides.”

Going to the Extreme

Absolute Combustion International (ACI), headquartered in Leduc, Alberta, highlights the following features of its Absolute Extreme Burner, which is used to recycle plastic film:

  • The near-flameless burner reduces flame impingement in a fire tube application, therefore reducing the cycle of fire tube maintenance.
  • Emissions produced from the burner appear to set a new low standard, without the need for a reburn of exhaust gases.
  • The burner is fueled by compressed air and natural gas and is a pressurized system once mounted into the fire tube. This pressurized system is designed to eliminate most of the atmospheric conditions that cause other burners to require ongoing tuning and adjustments.
  • The addition of a cooling jacket helps to reduce combustion chamber deterioration and reduce the extreme heat produced from the combustion tube wall. This cooling jacket contributes to the reduction of nitrogen oxide levels while at the same time adding to the thermal efficiency of the burner. The Btus (British thermal units) captured in the cooling jacket are fed back into the macro system without entering the fire tube. This contributes to a fire tube that can be shorter in length than traditionally thought.
  • In the majority of natural gas applications, the fuel is set at a constant pressure of 19 psi (pounds per square inch). The Absolute Extreme Burner functions at a very low fuel pressure and reduces fuel flow/Btus required, which reduces hazards related to high pressure fuel lines as well as the instrumentation costs.
  • The exhaust velocity harmonic (EVH) produces a noticeable turbulence causing a higher exhaust speed, which in turn reduces the exhaust temperature and increases the distribution of heat inside the fire tube. This EVH seems to contribute to the suspension of water vapor in the exhaust gases, allowing the burner to achieve exhaust temperatures of 380 degrees Fahrenheit compared with current exhaust temperatures of 800 degrees Fahrenheit in the majority of fire tube applications when using an exhaust gas analyzer.

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The author is a managing editor with the Recycling Today Media Group.