November 2008

Process Automation

Cleaning up a dirty business

Alternative fuels, emission reduction contribute to economy, environment

Fast Forward

  • Energy issues at forefront of manufacturers' strategies.
  • Tire recycling looks toward alternative fuel source.
  • Ultraviolet, electron beam curing reduces greenhouse emissions.
 
By Ellen Fussell Policastro

With oil prices, low supply, and an unknown future, it is good to know some manufacturers are forging a path of new resources. One Canadian company is taking tire recycling to a new level, while another in the U.S. is doing its part to reduce greenhouse emissions and improve productivity for food packaging manufacturers.

Environmental Waste International (EWI) is a company focused on developing systems to solve organic waste problems and economically improve the environment, based in Ajax, just outside Toronto, Ontario. The company has established a patented microwave technology called reverse polymerization, which promises to provide a new source for oil. The oil can be sold as a fuel for energy source. It can be sold and used by another group, or it can be used by a tire operation to produce additional power.

"So instead of just producing enough power to operate the system, by using the off gas, if you combine the off gas and the oil, you can produce twice the power required and thereby have excess power that can be sold to the grid or to an organization that has other facilities they want to supply the power for," said Dr. Stephen Simms, chief executive and president of EWI.

The process can break down a rubber tire in an environmentally friendly way, leaving behind by-products of oil, steel, and carbon black that are of high enough quality to produce a positive economic return, Simms said. "The system is energy self-sustaining based on non-condensable gases."

The company proved the feasibility of using reverse polymerization to break down and recycle scrap tires on a full-scale pilot plant, the Model TR-330, which they installed and operated at the EWI Ajax facility from 1994 to 1998. The facility processed nearly 300 scrap tires per day, and the lessons learned helped produce designs for the basic commercial unit, the TR-1500.

The most important thing Simms wants to do is raise awareness of the up-and-coming plants that will begin launching the technology. "As the public learns more about it, the applications are more than just rubber tires. There will be more interest in future applications and ways you can help handle organic waste, disposal, or recycling, recapturing the positive by-products out of the organic waste that can go into new products," he said. "The time is right from an economic and environmental standpoint. The world is waking up at the need to start looking at environmentally positive processes."

Technology primer

Reverse polymerization technology is a microwave-based technology. It works by applying the microwaves in a nitrogen atmosphere directly to any organic waste, anything that contains a hydrocarbon base. The microwave energy is able to excite the molecular bonds to the point they break apart. So it takes a complex hydrocarbon molecule and breaks it down to simpler forms. In the case of a tire, we take a 20 lb car tire (the North American standard of a used tire) and break it down to 7 lbs carbon black, 2 lbs of steel (just under a U.S. gallon of oil), and then the non-condensable off gases are put through a scrubber and passed into a turbine to produce the power to operate the entire microwave system for breaking down the tire. It is basically energy self-sufficient once it breaks down the tires. The excess oil carbon black and steel become the by-products to be sold to generate the revenue to make it a profitable business.

Tire recycling process

Scrap tires enter the processing area and proceed up the incline tire feed into the dry-feed tower. Each tire passes through a series of sealed shutters and lands on the conveyor, then proceed to the reverse polymerization process lines. It is within these sealed shutters that oxygen is replaced with nitrogen. Tires move along under the microwave launchers, which cause reverse polymerization to occur in the scrap tire rubber. Vapor manifold piping systems draw off process gases from the reverse polymerization chamber to condensers where the oil is collected. Remaining gaseous hydrocarbons are processed by a scrubber to remove the hydrogen sulfide. All the hydrocarbons can be used to generate electricity or can be sold as feed stocks for other industrial processes.
The carbon remains on the conveyor and is moved to the carbon crusher, which crumbles the reduced tires and assists in separating the carbon from the steel belts.  After passing through the reverse polymerization trap, the main conveyor dips into a water separator tank, where the carbon is collected and transferred to the carbon processor. The steel is washed and falls off the end of the conveyor into a storage bin. The process reuses or recycles 100% of the scrap tire feed.

The by-product pro-duction is the benefit to the automation industry. You have carbon black, which can be used back in new rubber products as a replacement for virgin carbon black. Carbon black as an industry is probably one of the higher end pollutants.

"And any way you can help with requirements for more virgin carbon black will help the environment," Simms said.

"If we are able to become a supplier that can offset the need for virgin carbon black, we are benefitting the environment. The production of virgin carbon black is a dirty business. It uses aromatic oil as its base. It draws on the oil reserve. The price of the carbon black is linked to the price of oil. So all these come together as an opportunity for this technology to make a difference."

Other applications

Carbon black is used in rubber manufacturing, so if a rubber manufacturer wanted an inexpensive source of carbon black to use as an additive in their product, they might be interested in setting up one of these facilities or joining with an existing one to have competitive priced carbon black. This would help keep their product more competitive in the marketplace, Simms said.

Companies will be able to link themselves with those making waves to solve environmental ills, at the same time creating positive cash flows for the operation and benefiting other companies that use those byproducts. Companies produce nearly 18 billion pounds of carbon black per year. It sees use with tire and other rubber manufacturing and as a colorant. Carbon black also sees use for tinting items that have darker black tinted paints, plastic bags, green and black garbage bags-anything that has additional wear resistance, such as the soles of shoes, or a treadmill at the gym, or in the ink industry for toners used in photocopiers.

Teeth to tires

Simms' initial interest in environmental waste management, aside from his background in computer programming and electronics came from his education in dentistry and infectious disease control. He gained an interest in applications "of this ability to break carbon bonds. All living tissue is based on carbon, hence organic waste," he said. "If you can break the carbon bonds, you deactivate any living tissue so any virus bacteria, or spores, are completely inactivated."

As a practicing dentist from 1983 until 1999, Simms had become involved with different corporations from the late 1980s. "I stopped practicing and began full time in the corporate business world, working mainly at this company, helping financing and raising money for the development stage and R&D as we began entering the commercial market," he said. Five years ago, the board of directors asked Simms to take over the company.

That background led Simms to work with medical waste, sterilization, wastewater, and finally work for Naval food waste sterilization. "After we did work with USDA in 2005, the Royal Navy in the U.K. approached us to design a system for sterilizing food waste on board Naval vessels," he said.  The technology has many applications, and they all fall under organic waste "because they all have hydrocarbons in them as the organic element," he said.

Potential markets

So far, the technology is still in the marketing phase with no results from real manufacturing use. But the company looks forward to a broad spectrum of potential customers. Some of those could include companies already in the tire recycling business or rubber manufacturing. "This would be a good way to begin recycling their product and gain a financial edge over the competition," Simms said. Other users could include investor groups who look at this as a business opportunity. The company is also working with some groups to establish a full operating commercial installation and retain percentage ownership and begin to set centers up across North America.

The pilot plant built in the 1990s operated for several years as a demonstration unit and to collect data for the advancement of the technology. "During that period, we went on to develop other applications. So the company was mainly focused on R&D," Simms said. In 2002-2003, there was a change in management, when Simms took over as president, and the mandate was to begin commercializing the technology. "The first area we became focused on was wastewater sterilization. We got a project from the U.S. Department of Agriculture. We delivered that system in late 2004, and it's been commissioned and running since 2005," he said.

Simms said he hopes the company will work worldwide with manufacturers in stainless-steel-based systems, and fabricators of stainless-steel equipment (tunnels), and conveyers. The electronic side of the system will involve microwave energy and those developing and producing power.

Ultraviolet and electron beam curing

Simms and his team are not alone in their quest to solve environmental issues. RadTech International North America has formed a Sustainability Task Force comprising a group of raw material suppliers-ink, coatings, and adhesives formulators; equipment manufacturers; end-use converters; and packaging manufacturers-to study and quantify the sustainability characteristics of these materials.

RadTech is a nonprofit trade association dedicated to the advancement of ultraviolet and electron beam (UV/EB) technologies. One of the task force's main goals is to develop quantitative comparisons of energy, emissions, and resource use of UV/EB processes versus conventional thermal curing alternatives.

"This technology is used in cars, fiber optics, DVDs, currency, and a lot of applications," said Gary Cohen, the executive director of RadTech in Bethesda, Md. "There are about 20 different areas on a car that uses adhesive and coating for components. You'd use UV/EB on that because it's fast curing compared with traditional methods."

Studies have demonstrated that UV/EB curing enables reduced energy use and green house gas emissions, primarily because of their high applied solids, and because UV or EB energy is used instead of heat for curing.

According to a 2008 RadTech Report, "Sustainability Advantages of Ultraviolet and Electron Beam Curing," by Ronald Golden, RadTech member and consultant at FocalPoint Consulting in Marietta, Ga., thermal curing must heat large volumes of air or generate radiant infrared energy to maintain the thermal curing oven at temperature or evaporate and remove water or solvent. They should also stay below the lower explosive limit when solvents are present as well as heat the substrate to the curing temperature and cure the ink or coating. Any volatile organic solvent emissions from thermal curing ovens require end-of-pipe controls (incineration or solvent capture). Both processes require additional energy input and generate corresponding greenhouse gases, the report said.

"The first real big application was for fiber optics where you needed to coat glass to protect it to make it more flexible," Cohen said. Traditional methods did not work because you had to cover millions of miles (you had to fabricate a huge amount of FO and it had to be fast.) "So they put a UV coating on, and it's ready. By shining a UV light on it, it cures the materials and they are ready to go. It's immediate pack and ship," he said.

A lot of technologies use applied coating that has to be baked and dried and sit for days. UV/EB means immediate curing. "Some say it's perfect technology for just-in-time systems," Cohen said.

In contrast, with UV or EB curing processes, reactive monomers replace all or most of the diluting medium and become part of the cured polymer, so little if any added volatile solvent or water is needed in the formulation, and effective applied solids can approach 100%, the report said. Curing is initiated by UV or EB radiation and is almost instantaneous, the substrate remains cool, and air circulation is mainly for equipment and substrate cooling and evacuation of any volatiles.

Previous analyses comparing UV/EB processes to competitive solvent and waterborne technologies have also shown substantial reductions in pollution and hazardous waste associated with spent solvent-borne materials and cleanup, as well as significant improvements in product performance and productivity, often at an overall lower net cost, the report said.

Coors, BASF case studies

The most complete published quantitative analysis comparing UV and waterborne technologies was a 1997 study of the conversation to UV curing from thermal curing of waterborne inks and coating for exterior aluminum can decoration and coating at Coors Brewing Company. A previous RadTech Report article reported how the conversion resulted in a reduction of up to 80% in total energy use in Btu, including electrical power and natural gas. Greenhouse gas emissions showed a corresponding reduction of up to 67%. Moreover, they saw benefits at a lower net cost for the finished product.

The RadTech Sustainability task force sought a more recent study to develop a similar comparison using current energy and emissions factors. BASF Corporation provided raw data from its coefficiency evaluation of waterborne, solvent, and UV web-applied pressure sensitive adhesives as the basis for its analysis.

On a normalized basis (Btu per square meter of coated substrate) the UV-cured resin requires up to 89% less energy, compared to solvent and waterborne systems.

According to the report, generation of electrical energy and combustion of natural gas generate corresponding greenhouse gas emissions. Factors for conversion of electrical MWh and combustion of various fuels to greenhouse gas emissions are based on data published by the U.S. Energy Information Administration and the U.S. Environmental Protection Agency. On a normalized basis (MT carbon dioxide per million square meters of coated substrate), the UV-cured resin generates up to 87% less carbon dioxide, compared to thermal curing solvent and waterborne systems.

Recycling UV-cured products

Trials at Beloit Corporation confirmed UV/EB inks and coatings re-pulp easily and have no detrimental effects on product quality. The study concluded manufacturers can recycle UV- and EB-printed and coated paper into tissue or fine paper grades using commercially available equipment.

The high gloss and abrasion resistance of UV- and EB-cured coatings in some cases allows users to replace laminated structures with printed inks and coatings. Laminated paper and plastics are difficult to recycle due to problems with separating two incompatible types of materials. UV/EB printed inks and coatings break down under recycling process conditions, permitting effective recycling of paper and plastic structure that formerly were intractable in laminated form, the report said.

The sustainability task force has already developed cradle-to-grave life cycle analyses for various coating and printing technologies, including energy use, carbon footprint, transportation, emissions controls, waste, recyclability, and more at each stage of production of raw materials and finished products and their disposal and recycling.

ABOUT THE AUTHOR

Ellen Fussell Policastro is the associate editor of InTech.  Her e-mail is efussellpolicastro@isa.org.

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