A major part of today’s communication revolves around Ethernet networking. In our world, this is used for either communications or I/O control. The current state-of-the-art network hardware makes the implementation of these types of networks extremely easy and secure. The fact that this is the same technology that is used in every corporation’s IT department makes it even more attractive.
After being involved in a number of migration projects, I’m surprised at how few of these considered taking advantage of the extra capabilities of fieldbus-based instruments, drives and positioners. This is not a new phenomenon, but it was more understandable in the early years of the technologies. To some degree the fault lies with the manufacturers. Fieldbus communication was marketed as being a way to reduce the number of wires required and the size of the cabinets required. To a great degree the real benefits of its ability to support smart instruments was a marketing afterthought, “Look at all the room you can save and, oh by the way, you get this extra information.” As a result, the typical migration project team says, “We already have all these HART instruments that give us the extra data and we’re not pulling any new wire, so why should we change?”
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.
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.
In the wake of the Deepwater Horizon disaster, alarm management has moved once again into the forefront for many companies as they ask: “What is the best way to keep an operator from missing a key alarm when things start to go wrong? What are the obstacles to having an effective alarm management system?” In my experience, the decision to have, or not have, an alarm is more often cultural than it is based on a good operational analysis of the process. That’s why the alarm rationalization process is so necessary and beneficial. It strips away the cultural, “I want the operator to know about…” and replaces it with, “This is the most important thing the operator has to do.”