The Intriguing Demise of Jurassic Control Strategies

Source: AIChE
  • Type:
    Conference Presentation
  • Conference Type:
    Southwest Process Technology Conference
  • Presentation Date:
    October 1, 2015
  • Duration:
    30 minutes
  • Skill Level:
  • PDHs:

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The petro-chemical industry has been around for decades. The industry has made advances in many facets of the business, but there are some parts that are reliable and have not changed in many years.

There is a term in economics known as “Creative Destruction”. Creative Destruction is the process of replacing outdated entities and stagnation with new innovation. Regulatory process control in many petro-chemical plants continue to use strategies developed thirty years ago. Process control consists of monitoring inputs and manipulating outputs using software, hardware, and human machine interfaces.

When the industry was young control valves opened and closed with air pressure that traveled through ¼” tubing from the control room to the valve actuator. In some cases, the copper tubing was up to 300 feet long. This technology made it quite expensive to manipulate valves from the control room. Control engineers developed split range control schemes that reduced the installation cost. This allowed for moving two valves with one piece of ¼” tubing.

The downside of the split range is having two valves but only one knob. Today the valve is still actuated with air but there is a pair of small wires attached to the transducer converting a digital signal to a pneumatic signal that changes the air pressure to the valve actuator. The pair of wires is inexpensive compared to ¼” copper tubing. This approach is called twin integrated control, and each valve has a dedicated set of wires. Two valves will have two knobs. The digital age is here.

Graphic interface to control systems is another area that needs innovation. Digitally we can do anything but often people who design graphic interfaces have very little knowledge of human factors engineering. Most graphics are designed using the P&ID approach instead of task oriented design.

The tough part of “Creative Destruction” is it may be painful to realize tremendous gain. Humans are creatures of habit and change stings.

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