Continuous Process Challenges Controls Retrofit Team

Rendering is the process of recycling waste animal tissue into stable materials that are used as ingredients in making livestock and pet rations and other products.  Upgrades to a rendering plant are particularly challenging because the plant receives a continuous stream of waste tissue from processing plants that has nowhere else to go.

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When a Kentucky rendering plant retained certified control system integrator Integrity Integration Resources (I2R) to design and implement a replacement control system, I2R project managers knew they had their work cut out for them. Employees work two shifts to process millions of pounds of tissue per week from multiple processing plants and there is no place to hold the raw material.

Because of this continuous process, rendering plants need an architecture that is highly reliable, provides for alarm and event data logging and response, and creates reports for optimizing plant operations. The client needed a supportable system, as well as redundancy and project management that included a risk mitigation plan. Of course, timely deployment was critical. In this case, planning, simulation and teamwork enabled a smooth controls retrofit.

Coordinated effort necessary

The existing control system contained two four-door electrical panels packed with nine vintage racks and 64 input/output (I/O) cards all controlled by a single programmable logic controller (PLC) processor. Two remote panels brought the count up to 77 vintage-class I/O cards with vintage wiring to match.

Technology deployed in the new system included Modicon Quantum fully redundant PLCs from Schneider Electric, uninterruptable power supply (UPS) backup for each processor, the Wonderware ArchestrA System Platform from Invensys Operations Management, and redundant servers and network switches.

The I2R team worked with the plant, corporate and electrical subcontractor personnel to upgrade the control system with no interruptions to operations. I2R was contracted to supply all of the PLC I/O panels, programming and design, as well as supervise the onsite electrical contractor supervision and onsite startup.

The upgrades were divided into five sections, each to be installed during a downtime window from noon Saturday to 9 a.m. Monday morning. With only 45 hours during which to work, the project manager had to make sure plans were complete, including contingencies, and the team was ready.

Because removing the old panels to make room for the new panels was impossible, a nearby lab room was repurposed to house the new panels. Pull boxes were installed above the new panels so that new wiring could be run from the plant floor to the new panels.

All new conduit and single-conductor wiring were chosen to replace cable tray. Conduit and wiring were installed while the plant was running. Once the new system was operational, the old tray and cable were removed. The plant also made spare Motor Control Center (MCC) buckets available, so the buckets could be re-built and tested on straight time instead of overtime.

A factory acceptance test with all of the panels was held at I2R four weeks before the first startup. A software simulation was held a week later. At simulation, operators and supervisors tried out the new software screens and asked questions. These steps eliminated surprises and saved expensive onsite time.

Although six startup weekends were planned, the number was reduced to five because of the preparation done by the plant and the contractor. I2R completed the entire upgrade on schedule, enabling a smoother operation with no unscheduled downtime due to controls after three months.

The plant manager attributed the success to the good working relationships of the team members: “The team that was put together ... fell together like peas in a pod. It was a great project experience with the relationships that were built among us all.”

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Louis Cusato, LouisCusato@I2R.com, is applications manager at I2R. A certified member of the Control System Integrators Association (CSIA), I2R is headquartered in Plano, Texas. More information about CSIA is available at www.controlsys.org.

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