With 353 million metric tons of plastics waste disposed of annually, more chemical manufacturers see opportunities to transform the discarded waste into fresh materials. At the Emerson Exchange event in San Antonio May 22, an engineer from specialty materials producer Eastman Chemical Co. highlighted how the company is using molecular processing technologies to reuse hard-to-recycle plastics.
Unlike conventional mechanical recycling, which processes plastic waste like water bottles into new products without altering their chemical structure, molecular recycling breaks down waste materials into their basic building blocks.
But the technology presents unique operational challenges. The process requires sophisticated automation and instrumentation systems capable of managing extreme temperatures—often reaching 600 degrees Fahrenheit—among other demanding conditions. The company deployed a series of Emerson instrumentation and control technologies to process the waste in the most efficient and reliable way possible, said Mike Strickler, an associate electrical engineer with Eastman.
Instrumentation key to optimization
Eastman has one plastics recycling facility currently in operation in Kingsport, Tenn., and two more scheduled to come online within the next five years—one in Longview, Texas, and another in Normandy, France. Strickler focused on the company’s polyester renewal technology (the company also employs a carbon renewal process for a variety of mixed plastic waste), highlighting how the waste stream moves along a conveyor to a dissolver where it mixes with chemicals and is heated to high temperatures.
“That was one of the areas where Emerson and their advanced technologies were very beneficial,” Strickler said.
In the past, the company had experienced either time delays or plugging issues with its instrumentation that it “couldn’t overcome,” said Strickler.
The company deployed the DeltaV distributed control system with four redundant DeltaV PK Controllers, which allowed Eastman to segregate various processes, such as utilities.
“So, if maintenance needed to be done, you could segregate and perform updates,” Strickler explained.
The configuration includes 32 DeltaV CHARMs I/O cabinets (CIOCs) located throughout the building close to process instrumentation to reduce wiring out to the devices. A key advantage of the deployment was the ability to use HART communication capabilities to access multiple variables from the plant’s process instruments, Strickler said.
Additionally, a networked data concentrator provided communication and control of motors and vendor skid equipment. This reduced wiring and I/O space and cost.
The company utilized Microsoft Device Manager with the system to help simplify the sensing and identification of the process instrumentation. On the instrumentation side, the company took an aggressive approach to measurement, with 285 Coriolis flowmeters used on the project, including the use of heat jacketing on some devices to gain more uniform heat tracing, said Teresa Edwards, senior sales representative, Emerson.
Instruments boost process understanding
The deployment also included about 400 pressure transmitters, the use of a dual-input temperature transmitter with hot backup configuration and 100 differential pressure transmitters, and 65 high-temperature vortex-shedding flow transmitters with temperature compensation for heat transfer fluid and density compensation, Edwards said.
When Edwards mentioned the number of flowmeters deployed, several session attendees seemed surprised. Edwards explained that Eastman is looking to refine the recycling process with verifiable data before scaling globally.
“I know these numbers sound big on the instrumentation side, but you have to remember this has never been done before,” she said. “Eastman has had this technology for over 20 years, but this is the first time that it went to production scale, so they wanted to make sure that they had enough instruments installed that if something went wrong, they knew why it went wrong and where. So, they wanted to make sure that they had the best technology in the line to give them the information that they needed so that Longview may be able to skip some of the hurdles that Kingsport went through.”
