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Improving Process Monitoring

By Patrick the Process Engineer

Mar 07, 2016
 

Process Unit monitoring is as much art as it is science.

 
 

Most process engineers inherit a process monitoring spreadsheet that may have been built years ago. A lot has changed since the early days of spreadsheets.  But has your process monitoring spreadsheet changed? 

 

If your spreadsheet simply mirrors the sequential arrangement for flow through the unit, you may not be getting as much out of your process monitoring spreadsheet as it can deliver.

 

Steps to Improve Process Unit Monitoring 

 

Hello my name is  No one spends more time in an operating unit or staring at the operating conditions of a process unit than the unit operators.  Spending time with the process operators will allow anyone trying to improve process monitoring to better understand the critical process variables.

 

 

Critical Readings  Know the critical operator readings especially the ones that aren’t fed into the control systems.

 

Figure out how to incorporate the “outside readings” into your monitoring package. A wise process engineer leverages as much technology as possible. 

 

 

 

 

Mass and Heat Balance  Good process monitoring starts and ends with good mass and heat balances around every piece of equipment (distillation columns, reactors, and heat exchangers).

 

 

Pressure is as Pressure Does  Companies make money by creating products from the feed of operating units.  Tracking and analyzing the pressure profile of an operating unit can lead to energy savings and throughput efficiencies.

 

 

Organize better than Ikea  There are thousands of variables in most operating units.  Simply dumping all the variables into a massive spreadsheet doesn’t leverage the full capability of process monitoring. 

 

Build a spreadsheet or database that leverages the most technology as possible. Someone back at university forgot to tell undergraduate chemical engineers to learn VBA which could be as important as fluid flow (not really but close).  The next few sections will help divide up the spreadsheet into manageable chucks.

 

 

On Test versus Off Test  In the tracking spreadsheet, organize the feed and product process information based on critical feed properties and product properties

 

Subdivide the properties into critical yield, reliability, and clearance specifications.  This will help you focus the communication of deviations to the correct downstream teams. For instance the metallurgy engineer doesn’t care if diesel cetane is off test.

 

 

 

 

Money Makers  Each unit has a purpose, otherwise why was the unit built.  Create a section that highlights and monitors the reason for the unit.

 

This may focus on reactor profiles and conversion in a hydrocracking unit or cat circulation and riser temperature in an FCC unit.  Or for our friends in the Amine Unit or Sulfur Unit focus on things such

as DEA loading ratios or reactor temperature profiles.  Another good idea is to use this section to tie unit economics to unit performance. 

 

 

Keep things from breaking  Build a section that focuses on reliability issues such as salt concentration, pH, and line velocity.  This will quickly and efficiently allow a chemical engineer to communicate with a reliability engineer. 

 

This is a good section to focus communication with local reliability teams.  Each side will be astonished with what the other doesn’t know about their business. Leverage this opportunity to close that knowledge gap.

 

 

Waste not want not  Utility systems are often forgotten and neglected by process engineers. Build a section that allows you to better understand the steam, water chemistry, and utility chemical requirements of your “friendly” NALCO representative. 

 

I find it comical how many refineries rely on an outside contractor to tell them when something this critical needs attention and how much money to spend on it.

 

 

Control This  Process engineers should think of themselves as “wanna be” process control engineers.  If you don’t know how the DMC or other control systems are moving the unit then you don’t really know what’s going on in the process unit. 

 

Your process monitoring spreadsheet should track all the control & manipulated variables (set points included). Use this as the discussion point for the board operators and control engineers. 

 

 

Time keeps on clicking  It may be generational, but convert all this data into visuals.  People can understand a graph much easier than a table of data.  But, be smart about your graphics. Build the graphics in such a manner to highlight relationships over time in a clean crisp fashion.

 

 

Cause and Effect  If you really want to show people information they can really use then build your graphics package around relationships not just time. 

 

For instance, if you’re really concerned about coker coke yield then maybe build a tracking relationship that has resid conrad carbon on the X-axis and coke yield on the Y-axis.  This sort of information is really powerful when communicating effects on changing operating conditions and for improving the refinery LP model.

 

Following these simple ideas about improving process monitoring will allow a process engineer to fully drive the most value from a process unit.

 
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  • Sean Moran :   Is Matlab something used far more in research and teaching than in process engineering practice? Do most process engineers use Visual Basic to do the things students are taught to use Matlab for?

    Jul 17, 2012

  • Mike Smith :   i've never come across anyone in the oil refining business use Matlab for anything. Excel is the gospel, and learning VBA is pretty powerful.

    Jul 17, 2012

  • Sean moran :   Thanks Mike...

    Aug 17, 2014

  • Bill Poe :   The importance of mass and heat balances is mentioned (as it should), However, seldom does raw plant data provide mass and heat balance closure. What are the recommendations for reconciling raw plant data and creating a valid mass and heat balance?

    Mar 09, 2016

  • Rich Andreea :   Bill, most refineries utilize compensated flow data to create more accurate mass and heat balances. Combining this, along with additional sample analysis, can help improve closure. There are also various industry yield accounting software solutions offered by niche companies; and also the big boys like Aspen and Invensys are in the game as well. In my opinion, some of the larger integrated software isn't worth the effort and cost. Let's focus on teaching these new generation process engineers how to properly do a mass and heat balance using first principles!

    Mar 15, 2016

  • Examhelpline :   Nice information . Thank for sharing article ... Examhelpline

    Aug 31, 2016

  • Lotsa Gray :   Great read, should be read by all the young unit engineers. One addition...find that old, cranky but probably busy engineer. The one you hear others say, 'go ask George, he probably saw this before.' He probably isn't in ops anymore on a unit; you may find him in Advanced control, Turnaround planning, small cap projects, senior site engineer, strategy or similar. Find him and try to 'drain his brain.' Those 20+ years 'here' are invaluable information; second only to operators.

    Jan 26, 2017

  • Lotsa Gray :   Great read, should be read by all the young unit engineers. One addition...find that old, cranky but probably busy engineer. The one you hear others say, 'go ask George, he probably saw this before.' He probably isn't in ops anymore on a unit; you may find him in Advanced control, Turnaround planning, small cap projects, senior site engineer, strategy or similar. Find him and try to 'drain his brain.' Those 20+ years 'here' are invaluable information; second only to operators.

    Jan 26, 2017

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