Monitoring Your Heat Exchangers in the Modern World

Most industries don’t use heat exchangers because they need them; they use heat exchangers because they save them millions of dollars a year in expenses. Whether the exchanger is drawing away heat to add efficiency to the cooling process or reclaiming lost heat to preheat fluid prior to a future heating process, the use of heat exchangers has revolutionized the industrial process.

 

For example, when crude oil is distilled in a refinery and transformed into useful products, it is heated at several hundred degrees. The heat from natural-gas-fired burners is effective, but not efficient, and certainly not free. Heat exchangers are able to capture much of this lost energy and recycle it. The heat is transferred to the incoming crude to preheat it. By lessening the number of degrees the crude needs to be heated by the gas burners, the company saves millions of dollars each year on fuel costs.

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In many industries, such as brewing beer, creating pharmaceuticals, pastuerizing drinks, and so forth, the temperatures need to be exact. Fluctuations in temperature could cause an entire batch of product to be lost. If heat exchangers are to be used effectively, they need to be able to maintain an accurate and consistent temperature control.

 

Maintaining accurate temperatures requires a knowledge of how the system operates, what causes it to work efficiently, and what sort of problems might cause an alteration to the process. For example, a dirty air filter might cause the system to work harder, thus generating more heat, while fouling within a tube might not allow for an efficient transfer of heat, thus requiring additional heat and pressure, and so forth.

 

Each of these issues would have tell-tale signs that could be caught by the watchful eye of a repairman or engineer if they were accurately and consistently collecting and charting data. After all, an engineer who knew the proper readings for the hot or cold fluid inlet and outlet temperatures, hot and cold fluid volume and mass flow rate, and hot and cold pressure changes across the heat exchanger should be able to detect any anomalies over a period of time. The problem is that many times the discrepancies are too small to notice, but over time they add up; kind of like collecting pennies in a 50-gallon drum.

 

Thankfully, with the advances in information technology, much of the work that was once done by teams of engineers over hours, days, and weeks can now be done by computers in milliseconds, and with a precision and accuracy that humans could never obtain.

 

Futurist Ray Kurzweil is known for the term “technological singularity.” It refers to the advancement of artificial intelligence to the point that it is capable of “recursive self-improvement.” Technological singularity would occur when the AI’s

advancement and capacity go beyond what a human mind can even conceive.

 

While we are not quite at the state of technological singularity, electronic gauges and indicators presently allow for continuous tracking of temperatures, pressures, flow rates, etc. The computers can then instantaneously make adjustments to compensate for any irregularities. Should there be even the slightest deviation that trends in a negative pattern, an inspection and/or repair can be ordered for problems that would have gone unnoticed in days past.

 

Granted, because we are not in the age of technological singularity, computers must be told what to do, and the data must be interpreted and adjusted by knowledgeable engineers.

 

  • The initial step in monitoring your heat exchanger in the 21st century is to ensure you have the correct temperatures, pressures, and flows. Make sure you have your system properly calibrated and that it is redundant. If one sensor fails, you want to ensure the second or third one will catch the problem.

 

  • Make sure your data is being read. Even a fire alarm going off in your house does no good if you are not going to pay attention to it. The system can call for an inspection or note a discrepancy, but is still takes a human to go and do the inspection and make the repairs.

 

  • Go wireless. Today, you don’t need to have boxes of paper printed out in the back room. Data can be fed wirelessly to portable computers, tablets, and smart phones. The engineer still needs to read and interpret the data, but you’ve made it that much easier by placing it right in their hands, real-time.

 

  • Verify the data. If you’ve ever had an error on your laptop or phone, you know just how easy it can be to have a file become corrupted. Systems need restarts, reboots, recalibration, etc. Make sure that the readings on your differential pressure are the same on your gauges as they are on your IT printouts, and so forth.

 

  • Go old school. For as nice as it is to have computers overseeing the data and making calculations in split seconds, there is still nothing better than the human mind when it comes to interpreting data, normalizing data, and making decisions based off of the data. This is assuming, of course, that the engineers know what the readings are supposed to be. This seems like a no-brainer, yet how many mistakes have been made with everybody saying the same thing, “Isn’t that just common sense?” If your engineers don’t know what the heat exchanger readings ought to be, or can’t tell you what the mass flow rate and pressure drop should be on the front and back side of the heat exchanger, then it is time to get them some training.

 

It’s funny how things can come full circle in an industry. The best way to ensure your heat exchangers are working efficiently and effectively is to go high-tech. Yet, the only way to ensure your technology is working accurately is to verify it with good, old-fashioned boots-to-the-ground systems checks and consistent, professional inspections and preventative maintenance.

 

 

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