The MOD Squad: Process automation at Dow

MOD 4 Goes Global
MOD 4 followed in 1975. It was the first process control system to perform all temperature and flow calculations in its software. MOD 4 expanded the I/O capability of previous MODs, and displayed values in engineering units, instead of percentage of full scale operation. MOD 4’s LSI-2 CPU expanded memory to 80 KB, and was again built by Computer Automation. Mod 4 finally made it possible to backup all inputs and outputs. Installation of a MOD 4 in the Methocel plant in Stade, Germany, was the first use of MOD systems outside of North America. 

MOD 5 Brings the Best Together 
Dow began using MOD 5 in 1980. Most of the first process control concepts remained in the MOD 5, but were greatly enhanced by the accumulated knowledge from implementing the system worldwide. MOD 5 represents hundreds of person-years of experience for automating and controlling processes accumulated over a mere 16 calendar years.

MOD 5 also represents the true collaboration of Dow’s multi-discipline work teams (chemical engineers, process automation, instrumentation, etc.). The MOD series development was a pivotal endeavor that linked our technology center philosophies with our operating discipline. We understand better that cooperation between research (get the right process), engineering (use the right equipment), maintenance (fix it once, never again), production (optimized and safe operations), business (automated scheduling, shipping, etc.) and many other groups must occur and improve for our company to survive and excel.

We really started to see tangible, operational benefits with MOD 5, including repeatability, as well as consistency and productivity improvements. Repeatability of best practices was extremely important because it enabled us to operate our plants safely, day in and day out, no matter what else we were doing. It helps us to do it the same way, every time.

Consequently, in the mid-1980s, Dow decided to implement MOD 5 globally. The standard systems approach used here was extremely powerful because it means anyone familiar with a MOD 5 system can immediately relate to the MOD 5 hardware and software running a process anywhere in the world. As of 2000, we had 1,500 systems installed and more than 400 information systems in place.

In the 1990s, there were several enhancements to MOD 5. A control computer was provided that physically combined control and safety functions in the same hardware platform. However, these functions were logically separated. This version of the system was SIL 3 certified. Dow was the first company to certify a process automation system with logical separation of the control and safety functions.

There were also major projects to address the human interface to the control system and the information management functions. The MOD Operator Station provides a standard graphical interface to the process control system, as well as an integrated environment for control programming development. A single standard information system and process historian was created by combining technology from several products developed previously.

Significant Results
By combining our best technology, we’ve seen tremendous productivity benefits added to fulfilling our operating discipline and safety performance goals. We reduced control strategy development time by 45%, and reduced support costs by 50%. Process startups are automated and coordinated across multiple unit operations. Alarms are “intelligent” in the sense that they reflect the state of the process, rather than just a deviation from a limit. Batch processes are fully automated, resulting in reduced cycle times.

Embedding our operating discipline concept in the automation system also helped us achieve our environmental, health and safety (EH&S) goals. All these performance improvements contribute hundreds of millions of dollars to our businesses.

Looking Ahead: New Sustainability Options
Of course, all strategies must adapt. So, the time came when we realized it wouldn’t be cost-effective to continue to invest in proprietary hardware and software systems. In early 2000, we decided change was necessary. While we wanted to preserve our process automation expertise, we knew that we didn’t want to be hardware providers, and so we began to look at other options.

The next article in this series will describe our quest to find a sustainable process automation solution that could take us into the future. MOD 5 would be a very tough act to follow.