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Do You Know How Your Refinery Blending System Is Doing?

In my travels as a Modernization Consultant, I often visit oil refineries to talk about modernizing their legacy process control systems. The usual discussions will focus on their main process units like the crude, fluid catalytic converter (FCC) and hydrotreating units. The users usually know a great deal about the control systems for these units but when questioned about the state of process control and other systems that run the blender, there’s a hesitation followed by ”Err, I’ll have to look it up” or “I’ll have to find out about that.”

Does this happen at your refinery? I have encountered this often and I thought I would put down some thoughts on, and apply lessons to, blending systems modernization from April 2016 ARC Insights titled “Owner-Operators Chime in on Building a Business Case for Justifying DCS Migrations” by Dick Hill and Mike Williams, based on user presentations at the 2016 ARC Orlando Forum – I’ll refer to this from hereon as ARC.

First off, per ARC, there are “currently, tens of thousands of control systems that are well past their expected lifespans that are still installed and operating … around the world”. Thus it will come as no surprise that all those blend control systems don’t receive the attention they need.

Blenders in refinery are where the final products that the refinery ships to its customers like gasoline and diesel are “made”. Often blenders are part of “off sites” which means they are literally off the (refinery’s) site and remote from the main areas. Hence the obscurity. They typically don’t get the care they need or deserve, and their systems are often aging and not current. Too often as ARC points out “Plant personnel must make extraordinary efforts to keep the aging technology functioning without significant system downtime or production outages.”

 Adding to these the challenges facing blend operations today like:

  • Governmental Regulations e.g. US EPA Tier 3, RFS2, EU Directive 2009/30/EC
  • Antiquated instrumentation e.g. turbine meters, manual valves, float tank gauges
  • Aging process controls/automation systems e.g. manual or analog based blending controls
  • Analyzers System e.g. antiquated/non-working/non-existent analyzers
  • Increasing cost of loss e.g. off spec products, too much blending giveaway

Blending is a complex process that involves many (sub)systems working together – measurement (flow, temperature) systems, analyzers systems (octane, RVP etc.) process control (blend ratio), and optimization and business systems. This makes modernizing blending systems complex and costly. Planning early is the key to success.

There is always the temptation to do a Replacement in Kind project as I discussed in my 2015 EE365 post, to this point, ARC states “Simply replacing the existing functionality would deliver zero incremental value to the new owners.” You would essentially net zero value for your investment.

Modernizing a blender or blending system involves more than just the blending controls hardware/software. You need to take a holistic approach and make the justification and planning process a project in and of itself. Zoom out and look beyond just the controls. 

1 Reply

  • Blending Process is a critical process. The Automation of the process involved in the initial stage of Process commissioning will be always one time installation and commissioning. Process operators will not Interfere with settings of controllers, unless new product is to be derived through blending or improve the quality of the existing product. Working on various proposals in the preparation offers for Blending Process, I experienced that the mechanical components (like skids etc.) are specific to the process design. Automating the skids is normally done through a SCADA system as cost effective solution. Our solution in the migration of the Automation system will depend on the new process Equipment's used in the Blending process.