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DCS Migration Benefits and Optimization Considerations

Posted By: Kevin Trantham on
Jul 20,2017

Distributed Control System (DCS) migrations, even if the desire is to limit replacement to ONLY duplicating current functionality, offer the following benefits when properly implemented:

  1. Improved reliability/avoidance of cost and risk associated with plant production loss because as a system ages, the probability of Failure-on-Demand invariably increases.

  2. Sustainable operations/longevity though enhanced flexibility and expandability in place of rigid obsolescence.

  3. Improved maintainability including: 

    • System improvements such as ease of troubleshooting since years of piecemeal change are replaced with an accurately documented, logically built system with a consistent modular approach and improved self-diagnostics.

    • Supportability due to expanded external knowledge base for life cycle system support.

  1. Improved third-party interface capabilities with systems such as Management Enterprise Systems (MES) providing elevated awareness and associated real time decision capability.

  2. A platform for future success through enhanced optimization capabilities.

    • Increased yield and quality.

    • Decreased product variability.

    • Improved operational awareness/decision-making capability such as alarm management, data focus, etc.

       6. Reduced life cycle cost.

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OPERATIONAL IMPACT MINIMIZATION CONSIDERATIONS

Aligning these benefits with an implementation process that minimizes operational impact with an effective cutover is of primary importance, regardless of the technology. For example, if a phased cutover strategy can reduce required overall downtime, and thus gain the plant a week of production, the value of increased production can often eclipse a huge portion of the project cost.  As such, minimizing operational impact, by selecting a technology that has the proper tools to support a phased implementation approach is often desirable. 

Required proper tools could include the following:

LEGACY INTERFACE CAPABILITY

DCS 1

DCS 2

DCS 3

Direct I/O

 

I/O Chassis

 

 

HMI / Graphical

Controller

 

Other (3rd Party) Systems

 


By insuring a DCS technology is able to provide these interface solutions, the flexibility to implement the project as needed in a phased approach to minimize operational impact can also be achieved.

For example, the following phases could be implemented: 

  1. Phase I: Replace operator consoles – requiring little to no downtime and joint operation capability for operator onboarding.
  2. Phase II: Add new controller capability with peer-to-peer and direct I/O Chassis – again with very little downtime.
  3. Phase III: Replace existing I/O in a staged approach in order to minimize operational impact.

DCS MIGRATION OPTIMIZATION CONSIDERATIONS

While performing a DCS migration, the decision must be made to either replace in kind, or to seek to optimize performance.  A decision to replace by duplicating the look and feel of the current functionality as much as possible is usually made to minimize the learning curve associated with the technology change, minimize the cost of the project phase, and minimize project phase risk. 

However, by including an optimization study component in the project, a more informed lifecycle cost decision can be made, as the return on investment is potentially significant.  To illustrate what can be achieved by such as study, consider the following brief and partial optimization outline:

Base Regulatory Control/Instrumentation

  1. The first step is to prioritize the loops affecting high value process areas in control of material and energy. (Normally 80% of the potential is contained within 20% of the loops.)
  2. Next, assess the current performance of prioritized loops via trends and control algorithm review against best practice approaches. Note any unreliable process indications or improper control elements.
  3. When the assessment is complete, look for common waste improvement areas, such as energy, excessive process variability, responsiveness, etc.
  4. Finally, quantify the potential improvement, and recommend changes for achievement where justified.

Advanced Process Control

  1. Advanced Regulator Control – In assessing base regulatory control, the potential for use of proper control algorithms is often discovered. Examples would include cascade, decoupling, ratio bias, feed forward, etc.
  2. Model Predictive Control/Modeling – As appropriate, using past process results or process upset reactions to properly model and drive future performance improvement can also yield significant improvement.

Batch Control

  1. Phase Optimization – Improving operator awareness, execution flexibility, and degree of automation can reduce total batch production time.
  2. Golden Batch Implementation – Minimizing product changeover, wait times, and batch execution variability can improve operation stability.

Operator Awareness

  1. Alarm Management/Prioritization
  2. Process Awareness/Human Factors Engineering

OTHER CONSIDERATIONS

Beyond traditional continuous and batch control aspects noted above, a number of other enhancements to operation can also be explored including the following:

  1. Coordinated Control – improving throughput/common equipment utilization.
  2. Management Enterprise Systems – Driving operational transparency on a real-time basis.
  3. Quality Assurance – Knowing what is produced, transitioning paper to glass with improved historization and electronic batch record keeping.
  4. Continuous Improvement - Whether you use an OEE, or a six-sigma approach, continuous improvement provides the data to drive awareness of key performance indicators and critical to quality parameters, and also makes obvious the primary detractors to their performance, so that improvement can be achieved.

Implementation should be considered to the extent that the potential benefits of the above items warrants additional project scope that outweighs any extra cost (project, learning curve, etc.). 

At Avid Solutions, we evaluate all the options that are currently available and determine how they can save your company time and money.

 

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