|
Article published in
Hot Mix Magazine, Volume 13, Number 1
Download this article in pdf format
INNOVATIVE SOLUTIONS TO ENVIRONMENTAL ISSUES
Environmental awareness and the regulations that tend to go with it—particularly in the western United States—will often keep hot-mix asphalt (HMA) producers on their toes. Just one new environmental regulation can mean that a producer needs to either retrofit his older equipment or go shopping for some new components. Luckily, CEI Enterprises of Albuquerque, New Mexico—a member of the Astec family of companies—is continually working to keep its valued customers up there on the cutting edge of environmental friendliness. How does CEI manage to do it? They do it by coming up with innovative solutions to environmental challenges and then including those innovations with their production equipment. Here are eight examples of CEI's innovative solutions:
|
Vent condensers for liquid-AC storage tanks
 The light volatiles present in liquid asphalt cement (AC) tend to become airborne when they reach elevated temperatures. When these light volatiles are exhausted from liquid-AC storage tanks and meet the cooler ambient air temperatures, a serious issue arises: blue smoke.
A vent condenser is a unit used to significantly reduce the amount of light volatiles that exist in a liquid-AC storage tank. In a conventional vent-condenser design, condensed fluid drains back into the storage tank. Not all of the light volatiles condense, and the exhaust fumes that exist in the vent condenser are still warmer than the outside air and, therefore, are still visible.
CEI created better vent-condenser designs that meet even the toughest environmental requirements. The models currently available feature multiple-pass technologies that incorporate replaceable filtering elements and options such as external cooling that gets liquid-AC storage-tank exhaust temperatures to under 120°F (49°C). These vent condensers can be installed on any conventional HMA plants that process products such as polymer or ground tire-rubber modified asphalt cements.
For producers who are facing the "super extreme" environmental regulations that exist in some areas, CEI can take an extra step to totally eliminate visible emissions. Radar level-gauges replace conventional level-indicating floats in a liquid-AC tank, eliminating a possible area where exhaust fumes could escape. For storage tanks already equipped with level-indicating float systems, CEI uses electrostatic air cleaners that capture and eliminate the remaining amount of exhaust fumes.
|
|
Crumb rubber: earth-friendly liquid-AC additive
 Each year, about 20 million tires are recovered, ground down to tiny pieces, and recycled into asphalt-rubber. There are many benefits to using crumb-rubber modified asphalt pavements: smoother pavements, better water drainage, and a longer potential lifespan. And as more DOTs discover these benefits, more HMA producers will be called upon to handle this kind of material. CEI has been making specialized equipment designed to handle crumb rubber in liquid AC for years. In fact, more than two-dozen CEI ground-tire rubber blending plants are currently in use in the western United States.
|
|
Pollution prevention starts with the right design
The potential for a plant to be a source of pollution is a normal concern for both producers and the permitting agencies they deal with on a regular basis. But with the advances in technology, it is possible to prevent pollution. With CEI's help, producers can set aside worries about meeting air-quality regulations and getting permits.
In addition to its standard diesel-fuel hot-oil heater, CEI can supply combination fuel/gas burners and low NOx designs that meet even the most stringent air-quality regulations. When required, burner designs are capable of getting their NOx emissions to as low as 20 ppm. CEI was also the first to introduce the "virtually dripless" hot-oil circulating pump. This centrifugal pump removes the possibility of transfer-fluid leakage and spills. With this hot-oil circulating pump design, the HMA plant is cleaner; transfer fluid is retained, and virtually no unwanted materials enter the environment. This design is standard on CEI's hot-oil heaters.
Other CEI products help the rest of the HMA production process run as clean as possible. On plants that run waste oil, for example, a waste-oil preheater on the drum burner can elevate the temperature of recycled fuel oil, enhancing the combustion efficiency, and reducing the levels of contaminants in the exhaust air flows.
|
|
Adapting to changes keeps equipment in spec and up to date
Equipping an HMA production facility with state-of-the-art, environmentally friendly technology is only half of the story. Keeping the equipment tuned and up-to-date is just as critical. CEI offers an extensive and responsive parts and service program to support its customers as they face increasing demands for environmental compliance and performance.
|
|
Double-walled construction for liquid-AC and fuel tanks
Local environmental agencies will always have concerns when an HMA production facility comes to them looking for permits. One of their chief concerns is the potential for spillage of fuel and liquid AC—even small, periodic spills that could, over time, seep into the soil and contaminate the groundwater.
You could invest time and money in constructing a permanent concrete containment structure for a stationary plant or a temporary stone-wall containment structure for a portable plant. But CEI offers a better solution:
Some of their liquid-AC and fuel-storage tanks come equipped with double-walled construction. The addition of an outer wall ensures that fuel and liquid AC will stay where it belongs. That means less work and planning for the producer—and less worry and concerns for the permitting agency.
|
|
The CEI RAP King™ drum mixer reduces emissions
When you think of being kind to the environment, two things come to mind: (1) Keeping the air clean and (2) Recycling used materials into new products. Both can be achieved with the CEI RAP King production facility. Using technology very similar to the proven Astec Double Barrel® design, the RAP King's drum mixer has an inner drum that efficiently conditions, heats, and dries the aggregate, while the outer drum utilizes the heat produced in the drying process to add, prepare, and mix aggregate, reclaimed asphalt pavement (RAP), fines, additives, and liquid AC. The drum-within-a-drum design also creates a cleaner production process. Hydrocarbons that are emitted from the materials in the outer mixing chamber are pulled back into the inner drum, where they are consumed by the burner flame.
The RAP King can run mixes with up to 50% RAP content without any visible emissions. The RAP King design is energy-efficient, as well: It is 4% more efficient compared with a similarly sized counter-flow system when running virgin mixes and 15 to 20% more efficient when it is running 50% RAP.
|
|
CEI will help you with permitting
The process of obtaining permitting from state and local agencies can be complicated and involved. But CEI has done it before—many times—and is in a position to provide you with advice, background and paperwork that can speed and often even simplify the process.
|
|
Energy efficiency helps the Earth's environment
...and it also helps your bottom line
 Reducing energy consumption is something we hear a lot about in our daily lives, but it is also essential to running a cost-efficient HMA production operation. When you lower the required fuel consumption in an HMA plant, you do two things: save money and lower the total amount of emissions.
That is the reason why CEI adopted a standard 6 in. (15 cm) of insulation on all of its heated tanks. And that is why CEI provides insulation for the asphalt and hot-oil lines. And why the company even offers some electrically heated options (as in this photo of an electrically-heated tank).
Genuine concerns for energy efficiency is also the reason fully modulating controls are standard on all of its heating systems.
|
Back to Top
|
