Get the Most HMI for the Dollar
Frugal plant upgrades lead to connecting multiple controllers to the same HMI, allowing for the addition of new functionality and solving obsolescence problems without busting the budget.
Ken Keiser, Siemens Energy & Automation -- Control Engineering, 11/1/2008
Jim Robertson wears two hats. As head of engineering at the Lanxess chemicals plant near Charleston, SC, he is responsible for the day-to-day maintenance at the facility. He also oversees capital expenditures for process improvements to the plant that was originally opened in 1978.
While most manufacturers separate engineering and capital work responsibilities, the Lanxess plant has achieved great success by combining these two job functions under one group. Over the years, Robertson and his team have used this uncommon approach to upgrade the plant’s batch control processes carefully in phases, avoiding downtime, and maximizing efficiency.
The company manufactures high-quality chemicals, synthetic rubber and plastics. Its portfolio includes basic and fine chemicals, color pigments, plastics, synthetic rubber, rubber chemicals, leather, material protection products, and water treatment products.
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| Older HMI components began to show their age, requiring costly and inconvenient repairs. This was a key driver as the company evaluated a system upgrade. Source: Siemens |
In the early 1980s, the Bushy Park, Goose Creek plant was controlled entirely with Fisher (now Emerson) Provox distributed control systems. This strategy was unchanged until 1999 when Robertson replaced a filter in the Vulkanox antidegradant chemicals production area that was controlled by a 20-year-old Provox DCS. Robertson’s choices were to keep the existing system and re-configure it for the new filter, upgrade to a newer version of Provox, or upgrade to another system platform.
After comprehensive market and batch application comparisons, Robertson chose the Moore Apacs+ system. A key factor in Robertson’s decision was his goal to move to a solution that adhered to S88 batch management concepts. He envisioned bringing all three of his production lines into accordance with S88 batch concepts.
Making the move
Over the next five years, with the help of system integrator AE Solutions, Greenville, SC, Robertson replaced the remaining two Provox controllers on the Vulkanox line with Moore Apacs+ systems. To minimize downtime, the upgrade was conducted vessel by vessel. By this time, Moore had become part of Siemens Energy & Automation.
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| A key element of the upgrade was to bring manufacturing in line with ISA S88 batch management concepts. Source: Siemens |
When the upgrade was completed in 2004, the plant was using two automated control systems, Apacs+ and Provox. The Apacs+ system automated the Vulkanox product line, while five Provox controllers and a ProView HMI automated the company’s Vulkacit vulcanization accelerator and Renacit mastication agent production lines. At this point, operators had no choice but to monitor and control the processes with two separate and independent HMIs located in the same control room.
Meanwhile, Robertson was facing lifecycle management issues with the ProView HMI hardware. For example, replacing a failed ProView keyboard was very costly and required the shipment of parts to the west coast for repairs. Additionally, Robertson was advised that the ProView HMI components would soon be discontinued, raising concerns about future part replacements or upgrades.
“I had already established myself as a bit of a rebel by moving away from Provox,” Robertson said. “But the whole idea of moving forward was that we didn’t want two HMIs any more. We had an Apacs+ HMI and a ProView HMI. The ProView HMI was obsolete, so we were on the hook to do something.”
Common HMI for both
In 2002 Robertson began the move towards a common HMI for both the Apacs and Provox controllers. Lanxess’ team, working with the assistance of AE Solutions, began developing redundant OPC servers collecting tag data from the Provox Hiway system. The tag data was served to Microsoft Windows-based clients running the HMI software. Using the extensive knowledge of the plant’s existing Provox controller configuration possessed by Robertson’s onsite engineering staff and with AE Solutions developing the OPC database and the client HMI graphics, the company took a large step towards successful migration.
Engineers at Siemens’ facility in Spring House, PA, offered to build on the success of this project and the lessons learned in the development of the Provox OPC server database to develop a new migration product for its Simatic PCS 7 distributed control system. Siemens already offered Moore Apacs, TI-505, and Bailey Infi 90 migration HMI products for PCS 7. Similar to the Apacs+ migration product, the Provox version would deliver the benefits of S88 batch management without having to change the existing Provox controller hardware and configuration on the Vulkacit and Renacit lines.
“We wanted to retain our investments in the existing controllers and we didn’t have the funds available to change out everything at that time,” says Robertson. “Additionally, the [Siemens] Spring House R&D team worked closely with us, spending a lot of time on site to ensure that the new product met or exceeded our expectations.”
Siemens new PCS 7 HMI was installed in August 2006. This solution allowed Lanxess to continue to use its Provox controllers without making modifications to the application software on the controllers. The new Simatic PCS 7/PVX OS HMI could also monitor and supervise the existing Provox controllers and the Apacs+ controllers, making the entire solution S88 concept based.
Batch management
The upgrade also included a change to Siemens S88 batch management software that gave Lanxess a consistent and traceable recipe management tool for product quality.
Using S88 batch concepts has supported multiple use of tested operations in unit procedures, reducing the amount of specialized or individual product code. Additionally, each recipe or order may be time stamped to analyze bottlenecks and energy savings.
The PCS 7 HMI automatically generated tags based on the controller configuration and was delivered with standard symbols and faceplates designed specifically for Provox tag types. The basic graphics used in the Simatic HMI are automatically generated using these symbols and faceplates. Lanxess operators and engineers then personalized these graphics using standard PCS 7 graphics tools to meet their needs. This same HMI also enables the operator to graphically monitor batches, create recipes, and modify batch parameters during runtime.
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| Upgrading the system provided an opportunity to clean up many years of disorganized wiring changes in the cabinet. Source: Siemens |
Like Robertson, Lanxess plant engineer Robert Durscher is also responsible for capital expenditures. He said the decision to install the PCS 7 HMI is in line with Lanxess’ lean operating philosophy that focuses on maintaining existing plants in the U.S., not building new ones.
“Frugal spending is something we have to do,” Durscher said. “We are in a very competitive global business, from engineering to janitorial services. This HMI solution is scalable, so we can keep running during changes and spread our capital requirements out over time.”
Some of the benefits of the Apacs+ and Provox controllers communicating through a common Siemens HMI system include a common point-and-click display, an integrated alarm management system and centralized data collection. Now, the HMI for all the batch lines are identical. Durscher feels that overall safety levels have improved now that operators no longer need to monitor two different systems while controlling different processes.
The new HMI and batch manager software gave Lanxess a common S88 recipe procedure structure over both types of controllers using clear and detailed displays. “Operators can watch the process progress through the phases now,” says Durscher. “They have actual batch displays and recipes providing a graphical representation of the batch. In the past, they would manage the process via short cryptic messages at the bottom of the screen to see what was going on.”
Configuration savings
Kent Wolcott, Lanxess’ process control systems programmer, said he spends most of his time with the plant’s operators. To him, the key benefit of the new HMI system is that it eases the load for the lean staff with easy recipe changes and revision control.
“We developed a tag type structure with the standard data base automation tools that come with the migration product,” says Wolcott. “Siemens developed the batch tools that automatically maps the Provox batch commands and statuses to those used with Siemens Simatic Batch. We didn’t have to configure any scripts.”
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| Before the upgrade, operators had to monitor multiple control systems simultaneously when running the Vulkacit and Renacit production lines. Combining these into one was a major goal of the project. Source: Siemens |
The graphical interface of the batch software has given operators a common communication point for operations, maintenance and engineering. Troubleshooting and analyzing the recipe/order is performed with a functional group using this tool.
“When we created this the first time during the migration to Apacs+, each DCD (distributed control device) had to be built with an individual display to show those text descriptors,” says Wolcott. “As a rough estimate, this consisted of about 500 displays. Now, the data base automation tool provided with PCS 7 enables us to enter these text values from a single generic display used by all DCDs, making my job a lot easier.”
Next steps
Robertson said the upgrade to the Simatic HMI has given him many options for future improvements.
“The next priority is to phase out the older controllers,” Robertson said. “We’ll keep the Apacs for the short term because the migration path right now is to replace all of the old Provox controllers. The new HMI system gives a wide range of options, including Siemens Simatic controllers, Profibus and new I/O products. Additionally, we now can phase everything in without downtime and without exceeding our capital expenditure goals.”
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