Live from WBF 2008-- Batch Management Modernization...a case study
Batch Management Modernization: Case Study of Upgrading and Adding S88 Features to a Legacy System at LanxessThis paper was given by Robert Durscher of Lanxess with assistance from Ken Keiser of Siemens. Batch Management Modernization In 1999: Batch control on Process line “X” was already established using existing plant equipment and DCS system with HMI I originating in the early to mid 1980’s Our plant was opened in 1978. The plant manufactures high-quality chemicals, using batch processes. In the early 1980’s, the first DCS was installed. As was typical of systems during that time, the batch software was rudimentary and not compliant to the then non-existing S88 standards. Between 1978 and 1999, the system worked well. However, external forces defined the longevity of the DCS. For example, the batch configuration of the controllers was not based on S88 standards, which lead to inefficiencies when the recipes needed to be changed; and the hardware of the HMI “I” was getting more expensive to maintain causing concern that the system integrity was at risk. Phase 1 Upgrade In 1999: Decision was made to replace filtration unit with different type; with a new DCS and HMI II from a separate vendor In 1999, a filter was replaced on the “X” line that required either a new controller or a re-configuration of the existing controller. It was decided based on the analysis to select a new vendor (vendor B) that could supply an S88 solution for that part of the plant. The other parts of the legacy system remained to control their respective areas. DCS, HMI and Batch Control upgrade to new manufacturer Using discrete channel communication to synchronize with the legacy DCS system within the process line Operators would initiate 3 recipes to make one batch One batch to run reaction portions of process A second to run filtration A third to run distillation processes The upgrade for the new filtration worked well. However, the control systems were integrated with each other and required other engineering to allow for sequencing through the process line. Since the new filter and controls were located in the center of the process line we were required to provide several discrete signals between the control systems to allow handshaking to take place for the equipment units involved. Also, the operator was required to use three different recipes to complete one batch. Phase 2 upgrade Upgrade HMI “II” to include communication with both systems Research to identify whether HMI I or HMI II is compatible to both systems HMI II compatible with OPC server that will connect with legacy DCS Allow operator interface with other processes remaining on the legacy DCS The plant recognized that under the current architecture there was a requirement for separate HMI’s for the plant process lines. After some investigation an OPC server package was discovered that would allow connectivity to the legacy control system. Upgrade HMI to include communication with both systems After installation of the OPC server package the new system HMI “II” was able to communicate with the legacy system for continuous points via a gateway as shown here. At this point, operators could monitor all plant processes but the batch manager was not yet integrated with the legacy system. Disadvantages with Phase 2 Engineering is manual intensive Engineering costs high due to length of time required Limited size of applications associated with HMI “II” required additional hardware and software licenses to complete project Still no batch functionality with legacy system Vendor B is now Vendor C and is phasing out HMI “II” Continue research for a path forward With the HMI “II” we also had several disadvantages. Without automation tools available for configuration the engineering was manual intensive and had high costs due to the length of time involved with the manual function development. In addition the different structure of the “tag structure” meant that full function conversion would require additional server hardware and software. And again, we had yet to implement batch functionality with the legacy system. Also, Vendor B had now been acquired by Vendor C and had announced that the availability of the HMI “II” that was installed in the “X” line would be stopped in 2007 and replaced with HMI “III”. Phase 3 upgrade Where to go from here? Replace control system for existing “Y” and “Z” process lines Legacy DCS system has different structure using integers to initiate operations and phases New batch control is S88 compliant using discrete signals for phase operation So, where do we go from here? Based on an analysis of the costs, there was one obvious option for the “Y” and “Z” lines, and that was to replace the system in a similar way as to the “X” line. This replacement option would have required a large engineering investment because the controller code would have to be re-written. Before the controllers and HMIs were replaced, it needed to be determined the requirements and feasibility of using the new S88 compliant batch management system for the legacy controllers. "Building the Bridge" We needed to configure scripts to translate batch control discrete signals into integer format for legacy system, and configure scripts to translate integer signals from legacy system into discrete format for batch control... The plant engineers determined the requirements for taking the S88 discrete signals and converting to the integer signals required by the legacy DCS. Testing batch functionality was begun and proven successful in 2004. With the batch functionality proven it was now possible to work with Vendor C in providing a permanent solution that would allow using HMI “III” with all plant controllers. This option would deliver the benefits of S88 batch management without having to change the existing controller hardware and configuration on the “Y” and “Z” lines saving the engineering invested in those controllers over the years. HMI "III" will include communication with both systems The new HMI would also contain a Batch Management system that would take the batch and recipe information from the legacy controllers and encapsulate that information into the new Batch management system so that the operators could control the batches of from any controller on a unified HMI system. This new HMI “III” would use OPC (OLE for Process Control) to communicate to the old system’s controllers. Vendor C’s solution for HMI “III” also provided several engineering tools to and automatically populate the database of the HMI “III” and batch manager saving migration costs. The legacy engineering station was retained to maintain configuration of configure the legacy controllers if as needed. Allowing for the future... When upgrading controllers for “Y” and “Z” lines there are more options available – like controllers built with S88 concepts. Migration is an almost continuous process. In the future we will need to upgrade the controllers for Process lines “Y” and “Z”. With the capabilities provided with Vendor C’s solution we do not have the same restrictions as what we normally would have. We could use Vendor A’s new controllers, Vendor C’s controllers or another vendor that has an OPC connection available.