Cracking on with it

Jan VersteegHow do you react when the costs of building a major new facility far exceed the original project estimates, placing a question mark over the feasibility of your expansion strategy?

This was the dilemma facing SABIC Europe in June, when the current spike in construction and steel costs led it to postpone (see panel page 20) a major expansion at its base in the southern Dutch town of Geleen. The decision prompted a strategic rethink at the site, which houses two naphtha crackers and world-scale polyethylene and polypropylene production facilities.

“SABIC remains committed to its strategy of growth for the important European market” and will review “all options such as the upgrading of the current asset base and supply from the global SABIC system,” stated Frans Noteborn, the then CEO of SABIC Europe.

The operation has consequently switched its focus to optimising its current asset base through the application of advanced information & communications technology, automation, instrumentation and equipment reliability systems.

Much of this work is being guided by the site’s Competence Center Manufacturing, where a current emphasis is on implementation and optimisation of the manufacturing execution system (MES) and developing the interaction of workprocesses in MES and ERP layers.

“Now that Europe1 is postponed, SABIC Europe is looking to further optimise the performance of the site under a new coordinated manufacturing programme,” explained Jan Versteeg, operator information management system consultant at the Competence Center.

The Geleen operation employs distributed control systems (DCS) from Honeywell and Emerson, while the MES system is based on AspenTech technology.

“As the DCSs are from the 1990s we are involved in several maintenance programmes to replace these with the latest versions,” said Jos Oelers, ICT consultant & infrastructure manager, at the Competence Center.

Emerson’s Delta V digital automation suite “is coming in as a smaller project but later there will be major replacements that we will have to deal with. The same holds for the top layer of the Honeywell systems,” he added.

For Europe1, the company has also “involved the possibility of a third DSC vendor for Europe-1,” noted Oelers. “We performed an extensive business case with focus on total cost of ownership.”

SABIC Europe, meanwhile, plans to implement asset management tools in a part of the Geleen plant by mid-2007, said Ruud Litjens, process control engineer at the site’s LDPE (low density polyethylene) production operation.

“We are installing Emerson’s AMS tools and smart transmitters so a maintenance engineer can see if that part of the plant is healthy and send someone to the plant if there’s the problem,” he said.

The MES layer between the DCS system and below a company’s ERP system can be very profitable if you make good use of the available technology, Versteeg noted. He cited, for example, how SABIC Polyolefine, SABIC-Europe’s German site, generated returns of around Euro12million/year from an investment of around just Euro4 million. This, he said, was similar to that achieved by a benchmarked project at a 750ktpa (kilotonnes per annum) polyolefin plant in the US.

The gains stem from improvements in areas such as prime rates, on-stream efficiency and consumption. About a third of the returns relate directly to the APC system, two-thirds result from better working practices. “The higher quality of information enables faster and more effective decision taking,” Versteeg explained.

SABIC Europe is further supporting its growth ambitions through the implementation of the latest APC (advanced process control) technologies at the 550ktpa LDPE production operation at the Geleen site.

Litjens, together with the Competence Center, has recently upgraded the APC system on its S17 tubular high-pressure LDPE plant, which is based on SABIC technology. The 180-ktpa unit is the largest such reactor at the site and carries out over 200 grade change transitions per year.

The APC system is based on AspenTech’s non-linear model predictive controller (Aspen Apollo). This is part of the aspenONE APC for Polymers suite, which also includes Aspen Process Recipe for recipe management, Aspen Transition Manager, and Aspen IQ — for model-based inferential measurement of melt index and gloss.

Unlike conventional linear APC controllers in polymer plants, which are typically only switched on during in-grade operations, the Aspen Apollo non-linear system can control the process during product transitions as well. SABIC Europe has been one of the companies pioneering this non-linear control technology, including an earlier pilot project with Apollo at its Gelsenkirchen site.

The S17 project, now under evaluation, promises a return on investment within a year. Benefits are shorter grade transitions and reduced process disorder after transition.

The APC software, added Versteeg, has reduced variation in product quality and is enabling the company to reduce or eliminate costly laboratory analyses and in-line measurement equipment.

“Before, when the operators had to do the transitions by hand, you got a very wide distribution varying from 30 minutes to sometimes two hours,” Litjens explained.

“What we tend to do with Aspen Apollo is not to go for the fastest times but to do the transition always in, for example, 40 minutes to integrate efficiency and reliability in every transition we perform.”



Minimise problems

With Aspen Apollo you minimise having problems during the process, commented Versteeg. “Apollo’s attention is continuous, 100% of the time available, does not suffer from shift-changes and has a longer prediction horizon than a human operator.”

SABIC Europe has significant experience of implementing APC technology and maximising the benefits of this technology.

The S17 project is just the most recent in a series of APC projects, which started with the implementation of AspenTech’s DMCplus linear APC software on the NAK 3 cracker — the first major model predictive control project at Geleen.

The APC project on the NAK 3 unit served to increase ethylene and propylene production and reduce energy costs as well as other unexpected benefits, said Joep Bazelmans, plant automation engineer at the Competence Center Manufacturing.

“Looking back, you can see that an ethylene plant was always focused on maximising production of ethylene and not at the same time maximising output of propylene. With APC, we found we could maximise both at the same time,” said Bazelmans.

Indeed, noted the engineer, the system’s feed maximiser turned out to be the main profit generator because it increased furnace loads until a constraint such as feedstock bottlenecks in the back-end was reached.

Total feedthrough increased 10%; with ethylene up 3% and propylene 15% higher, said Bazelmans. “For propylene, we had expected something in the 2% range. This was a big plus.”

The cracker operation became much more stable and quiet with less alarms, less operator interventions, continued Bazelmans.

“It becomes a minute-by-minute process so you generate a smoother operation. An operator will put in one tonne at a time, for instance, and [APC] will do this at a few kilos per minute,” he said.

The SABIC Europe team also cited how APC has provided energy savings from operating the furnaces closer to the ideal oxygen/fuel ratios and generated less demand on safety systems because of the enhanced stability of the operation.

The key issue for companies implementing APC technology concerns their getting operators fully on-board the project, Litjens saying: “Acceptance is very important. It is like a train and we have to make sure that nobody falls off.”

Operators can find it difficult to understand the application and so turn off the controller, according to Litjens. “We have to show them that it would be better to have kept it on as the more room you give Apollo, the higher the production rate.”

It takes time to get familiar with the APC system, agreed Bazelmans. “You have to get used to how to work with it and not constrain the control too much.”

Another issue for the Competence Center team is the company’s relationship with its software system suppliers.

“You are very naked with your technology towards the vendor because, for instance, if you are doing a transition, the APC vendor will automatically know how you do transitions. There is a very delicate balance between what we know ourselves about our processes and giving AspenTech what it needs to know to make the tool work,” Versteeg said.

Until now, the main focus for the SABIC Europe engineers has been on the DCS and MES systems. However, said Versteeg, the performance of the integrated chain is what finally counts, which brings ERP into the picture.

SABIC Europe has launched two projects —called Diamond for the polymer side and Sunrise for olefins — for the complete optimisation of the supply chain. This encompassses the Geleen and Gelsenkirchen operations as well as the company’s overseas imports.

“In polymers there is a more clear separation of those work processes supported by the ERP and MES layer. So, manufacturing support to the optimised supply chain is about being a reliable producer: reliable production of the agreed quality and amount at the right time.” said Versteeg.

“Automating the decision-taking process to hand over production batches to the logistic department avoids unnecessary waiting times. A performance indicator shows how much the plants make use of the automatic mode of the interface between MES and ERP,” he added.



Olefins complex

Integration of work processes in the ERP and MES system is much more complex on project Sunrise, according to Oelers. Feedstock, plant capabilities, actual storage situation and the financial margins of the products in downstream plants all directly influence daily operations of crackers and logistic operations, he explained.

The olefins project covers the items of the product supply chain, the feedstock supply planning from Rotterdam, pipeline scheduling and site flow and production scheduling, continued Oelers. This, he said, requires an extensive integration of processes supported by the ERP and the MES layers.

This effort includes work on a new AspenTech solution, called Aspen Olefins Scheduler. The company is now deciding on which areas will be covered by this product and which will be covered by SAP, the governing system for the ERP layer.

Ruud LitjensSABIC (Saudi Basic Industries Corp.) recently postponed its Europe1 expansion plan at Geleen, citing a sharp rise in contracting and construction costs due to the spate of massive industrial investment projects worldwide.

Jos Oelers



Under the Europe1 initiative, SABIC plans to install 400ktpa of ethylene capacity and two downstream polyethylene plants, for LDPE and HDPE, and one for polypropylene.

SABIC is, however, going ahead with the construction of a new HDPE plant at its production site in Gelsenkirchen, Germany. The new 250ktpa plant will come on stream in 2008 as part of a Euro200 million expansion project at the site.