Automated material recovery system more than doubles recovery of key recyclables
Action Environmental Group, one of the largest solid waste and recycling providers for the five boroughs of New York City, used automation to help the group’s recycling company, Action Environmental Solutions (AES), more than double separation of recyclable material collected the city’s commercial buildings. The resulting piles of paper, plastic, and aluminum are bundled into large bales, which are then marketed to international buyers. Those bales are repurposed into shoes, water bottles, and new paper. The automated facility uses programmable automation controllers, human-machine interfaces, manufacturing execution software, and variable frequency drives. [This is part of the Control Engineering March 2015 cover story.]
International buyers want the lowest levels of contamination—meaning materials other than what is supposed to be in the bales. For example, China’s "green fence" policy restricts this level of contamination to 3% or less.
However, local laws can make this difficult. New York City mandates that all recycling material be contained within plastic bags and picked up at curbs. This commingling can lead to greater contamination of materials.
Manual to automated separation
Before 2013, AES operated one recycling plant—including one picking station, one screen, and a few balers. Employees manually separated recyclable materials. Without automated systems, employees were limited in how much material they could gather from quickly moving conveyors, and the plant was losing a lot of material that could be marketed and sold.
The company wanted to decrease contamination in materials and increase the amount of material the system tossed. By creating more bales of recyclable material, the company would also keep more material out of landfills.
Automation technology for recycling systems has dramatically improved and expanded since AES built its existing facility. The AES team decided to build a facility that would automate the recycling process. The goal: separate more tons per hour of the most valuable recyclable material. The automated system would include more screeners and magnets to pull out aluminum and plastic, and optical sorting units to target the white and high-value paper.
This advanced recovery equipment would come from several manufacturers. AES needed an integrator who knew the demands of recycling firsthand, with an engineering staff that could coordinate the equipment and automate the facility. Vecoplan, a builder and automator of recycling technology, took on the project.
As AES coordinated with manufacturers to bring in advanced sorting and processing machines, Vecoplan designed the system’s controls.
This was no simple task. The new material-recovery facility in the Bronx would be the largest of its kind in the metro area. Its size and complexity required tight controls over conveyor speed, optical sorters and other intricacies of the process.
The process starts when trucks bring in loads of mixed waste and discharge it onto the tipping floor. A grapple scoops up recyclable material and loads it into one of two metering bins. These weigh each load before it goes onto the conveyors. As material moves down the line, optical sorting units use infrared technology and high-speed cameras to sort the high-value white paper from the mixed paper and other materials.
Next, a series of magnets gather tin and aluminum, and a final optic sorter separates high-quality plastic. Workers along the conveyor line help ensure as much recyclable material is gathered as possible.
Two programmable automation controllers (PACs) manage all machine functions and seamlessly integrate with other system components via the EtherNet/IP network (an Ethernet protocol from ODVA) and other networks. The first PAC manages the first half of the system, containing the general sorting, and the second PAC manages the specific sorting.
On-site operators can monitor the entire facility’s function and throughput with four human-machine interfaces (HMIs) on the floor. They can make manual adjustments down to the component level—from speeding all conveyors to slowing one specific optic sorter.
The HMIs contain troubleshooting guides that operators can access if there is an issue on the line. The guides provide step-by-step corrective actions and detailed photos, down to the component level, to help operators fix any glitches and reduce downtime.
Operators can access the data from the HMIs on the floor and in the central control room. For motor control of the system’s 70 conveyors, the company chose variable frequency drives. The drives’ data are sent via an EtherNet/IP network to the master control room, giving operators further insight into facility operations.
Double the recycling
AES now goes to market with higher-quality bales of recyclable material, containing less contamination to meet international standards. For example, the older recycling facility sorted out 25 tons per month of high-quality plastic. The Bronx facility produces an average of 65 tons per month.
With the optical sorting units, the new facility sends between 400 and 500 tons of white paper to market each month—that compares to 250 tons per month previously.
"There isn’t another facility in the city that produces bales like ours," said Ron Benson, project manager for AES. "With the facility’s advanced automation and controls technology, we’ve been able to maximize our throughput and minimize our downtime."
The most impressive result is the amount of aluminum the system sorts. During five years at the older facility, the company marketed five tons of aluminum. Within six months of the new facility’s opening, the system had produced 63 tons of baled aluminum.
Overall, the Bronx facility sorts through 300 to 400 tons of waste and recyclable material daily. The facility is looking to increase that amount, up to 10,000 tons monthly.
The benefits of that growth extend beyond financials. By taking more re-usable material out of the waste system, the facility reduces pollution and greenhouse gases, and saves landfill space. If the facility’s capacity reaches the limit, it will keep enough material out of landfills to fill more than 300,000 square yards.
– Kim James is the marketing director at Vecoplan. Edited by Eric R. Eissler, editor-in-chief, Oil & Gas Engineering, CFE Media.
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