Have you ever thought about how many average families have been changed by having GPS devices in our cars? Just think back to the (not so) good ol’ pre-GPS days when you pretended you knew where you were going, only to find out you didn’t, and you never heard the end of it. When those wonderful gadgets came along, they put a stop to all the arguments about directions. Yet the change snuck up on us so quietly, it went mostly unnoticed. I see the same thing happening in our industry with variable speed drives (VSDs), including variable frequency drives (VFDs) and inverters. Yes, we all know you can reduce energy consumption while improving efficiency and process control by using VSDs to drive pumps and blowers instead of using flow restriction devices. But that’s not what I want to talk about. What I want to focus on is how much the cost of modern VSDs has dropped in recent years....

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Distillation columns are one of the most often used unit operations for separation and purification in the process industries.  They can also be some of the most complex to operate and control, because they involve two-phase, multi-stage, counter-current mass and heat transfer (each tray or segment of packing is a theoretical equilibrium stage).  The greater the number of trays, the longer the time constants related to composition changes. For a two-product distillation column (top and bottom product), there are typically five degrees of control freedom (control valves):

• Reflux flow
• Top product flow
• Reboiler heat input flow
• Bottom product flow
• Pressure control valve (the specific location depends upon how the pressure is controlled).

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ERP systems are supposed to be the “silver bullet” of computer systems. They’re supposed to solve just about every business problem you might have. They’re supposed to handle finance, purchasing, logistics, orders, shipping, inventory, manufacturing, maintenance and everything else with a beautifully integrated suite of modules. And, you know what, except for the “silver bullet” part, ERP systems have actually delivered a lot of what they’ve promised. They really have done pretty well in finance and purchasing and logistics and several other areas. For most companies, ERP has been worth its weight in gold just by providing an integrated set of financial records and all the tools you need to manage the financial transactions of the company. ERP doesn’t have that same track record when it comes to manufacturing, however. ERP doesn’t really support manufacturing that wel...

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Quite often, automation projects become a plug-and-chug exercise in getting the code and HMI into the control system, according to the specifications, with little thought to the true purpose and strategy. This type of automation implementation can be successful, but does not protect your process from the dangers involved in making control system changes. Before someone modifies your control system, do you check to make sure they understand the process they’re working on? Do they even take the time to ask good questions? With today’s advanced technology and intuitive tools, you can find people who can code logic and draw pictures — but are they really experts, and are they looking out for your plant’s best interest? A successful automation project starts with all team members aware of the process they’re working on, the economic drivers that make money for the pla...

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