7/27/2019 CS Process Control n Material

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C Process Control & Material HandlingCONTROLNET SOLUTION

tegron5912D Old Highway 80 Longview, TX 75604-6010903.759.1088www.tegron.com

An outdated relay panelboard and multiple control rooms are replaced with adistributed PLC-based control system and

plant-widecommunications network.

Eastman Chemical Companys Texas EastmanDivision (Longview, TX), one of the largest polyethyl-ene plants in Texas, produces approximately 9 millionpounds of material per day, which is then sold tomanufacturers of polyethylene film, paper coatings,and injection molded products. Eastmans materialhandling system, which moves processed polyethyl-ene pellets throughout the plant, is comprised of

approximately 186 multiple storage bins, 74 producttransfer systems, and eight extruders. The systemcontains 850 devices.

The previous material handling control systemconsisted of a relay panelboard and multiple controlrooms containing wall-mounted switches, lamps, andmeters. Colored lines on the control room wallsdepicted possible routes from extruders to storagebins and storage bins to railcars. Control roompersonnel operated field devices using switches onthe wall after verbally confirming diverter, mergemanifold, and gate positions with other personnel inthe plant. The system was not reliable, flexible, or

fast enough for Eastmans rapidly expanding needs.Tegron was enlisted to help replace the outdatedcontrol system. Eastman wanted the new system tohave the ability to log every I/O event, diagnoseproblems in the process, and transmit data to a plant-wide historian.

Eastman decided to implement its improvement planin three phases. The system included installing twoAllen-Bradley PLC-5-based control systems and state-of-the-art ControlNet networks for I/O communications.

The system consists of nine logic control panels,representing more than 2300 digital and analog I/Opoints, and seventeen Allen-Bradley PLC-5 racksconnected via ControlNet to two PLC-5/80Ccontrollers. Ethernet sidecars were installed on thePLC-5s for messaging and communication withhuman-machine interface (HMI) workstations and thdata server.

Tegron provided a custom Visual Basic data server,allowing operators to select a specific route frommore than 1.2 million possible material flow paths. Afast messaging system was developed between thedata server and the PLC using Rockwell SoftwaresRSLinx software, which allowed the data server to tethe PLC-5 all the job parameters and devices. Tegronalso created a virtual network within the PLC, whichallows operators to run paths while the PLC emulatesthe I/O parameters.

On the HMI side, graphics and logic were developedto allow the operator to monitor and controlpreselected flows. The PLC-5 system isolated HMIdata to support fast-as-possible update of, andresponse to, the operator.

The system resulted in several benefits for TexasEastman: increased information flow among the PLCHMI, and data server; ability to log all of the I/Oevents; real-time diagnostics; and organizedpanelboard.

(A 1999 update of Controlling the Manufacture of Polyethylene, Control Engineering, Mid-December, 1997, 1997 by Cahners Publishing Company.)

SPECIFICATIONS

Technologies PLC 5/80C 1771 I/O FIX32 Ethernet ControlNet RSLinx Visual Basic

Technical Goals Control 850 devices Manage 1,200,000 product flow paths Log every operator & I/O state change Evaluate time-critical process regulation Provide redundant architecture Provide auto-failover system

Production Benefits Centralized control Increased product quality Less material waste System verification Simple setup and operation Rapid product changeovers