Alarm management reveals hidden plant capacity

Air Products and Chemicals implemented a comprehensive alarm management programme at its Calvert City ethylene vinyl acetate plant.

Proper management of alarms and alarm data can be a significant source of "hidden capacity" in a plant, as Air Products and Chemicals (APC) discovered when it implemented a comprehensive alarm management programme at its Calvert City ethylene vinyl acetate plant.

Air Products was looking to make three improvements to its plant performance: a reduction in off-spec product, an increase in capacity by reducing cycle time and, due to reassignment of duties of the control-room staff, a better way to present and prioritise alarms.

Complicating matters was a 20-year-old DCS with no built-in alarm management mechanism.

It would log alarm information directly to printers and text files, but users could not electronically access data such as alarm summaries, and were not able to perform more complex alarm analyses.

A multi-million-dollar upgrade or replacement of the system was not an option.

APC needed a relatively low-cost solution that would work with its plant's legacy DCS to turn underutilised masses of alarm data into useful industrial intelligence and unlock the operation's hidden capacity.

In 2003, APC partnered with Matrikon to implement its award-winning ProcessGuard alarm management product at Calvert City.

Matrikon's ProcessGuard solution provided a grip on alarm data in three very different ways in order to meet APC's requirements.

In the first part of the solution, metering alarm data is used to reduce off-spec product.

Alarm messages with metering information were captured by the software, which then exported it into Excel reports.

That prepared data are then used to identify meters which are not performing correctly, so APCI can pick out problem meters before a batch is made.

By catching metering problems early, it was expected that APCI could reduce waste and faulty product.

The second aspect of the solution is an effort to increase overall capacity by reducing process cycle time.

Sequencing data is captured by ProcessGuard and stored in batch records containing information on cycle time, phases, steps and parameters associated with the quality of the phase.

This data had previously been transferred manually, with resulting inaccurate and missed data.

With complete, accurate data available electronically, discrepancies in cycle times for batches, phases or steps can be easily identified and the root causes of these discrepancies can be pinpointed and rectified.

Finally, an overall alarm rationalisation was performed, and a state-of-the-art alarm management program implemented.

Air Products used the software to identify alarm problems, reduce frequency of alarms, and rank alarm data by frequency.

Plant management and DCS technicians met daily and reviewed the previous day's top 20 alarms, identified obvious nuisance alarms and addressed them by changing alarm limits, deadbands etc as needed.

Once the majority of these chattering alarms were corrected, the software was used to identify parent/child relationships between alarms.

Each parent/child group was then analysed with an eye to long-term process improvement.

Following commissioning and implementation of these three solutions, each of the targeted areas saw substantial improvements with direct operational and bottom-line benefits.

The meter-alarm monitoring and intervention project saved engineering and equipment time due to early detection of metering problems.

Inventory was reduced due to first-time material out of the reactor maximising capacity and reducing cost.

Overall, the solution enabled a 20% increase in meeting product specification.

The attempt to give production a bump by analysing and correcting timing discrepancies to reduce the cycle time of reaction was a great success.

Overall capacity at Calvert City was increased by three%, without capital expenditure - hidden capacity that was just lying inside the process, waiting to be tapped.

In the first two months of the project, an 80% reduction in the number of alarms was achieved by maintaining a sustained engineering effort on alarm management activities - an ongoing process.

Where there were five people in the control room watching alarms, the job is now handled easily by one using ProcessGuard's web viewer to display, filter, sort and prioritise alarms.

What used to take up to one week is now accomplished in a matter of minutes.

Overall, Air Products realised a total return on effort and investment in just three months.

With a single software solution, a serviceable plant with a legacy DCS was revitalised - without replacing or upgrading physical assets.

Based on this success, Air Products is planning to implement similar ProcessGuard solutions at other plants.

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