A Caloris customer reported problems with their evaporator, including trouble controlling evaporation and maintaining vacuum. We sent an engineer to the site to perform some basic troubleshooting tasks.
First, the engineer performed a “vacuum pull test” where he pulled as much vacuum as he could while the system was idle and looked for leaks and recorded the rate at which the vacuum eroded. Then he broke vacuum and filled the evaporator with water as high as he could, looking for places where the water was leaking out. Filling the system with water and applying vacuum helps identify leaks around the pump seals, gaskets and any structural cracks in the vessels.
The above tests revealed a leaking manway gasket in one of the evaporator passes. This particular leak was causing product foaming and reduced heat transfer efficiency by 50%, causing the unit to perform below its design parameters. Simply replacing the gasket solved that particular issue.
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The customer had already identified an additional leak around a pump seal, which was contributing to fluctuations with the degasser level control loop. Stable control of this loop is needed for a constant flow of feed to the evaporator. After repair of the leaky pump seal, our engineer retuned the loop and stabilized it.
Our engineer also noted that the CIP system wasn’t calibrated to the proper temperatures to allow for the chemicals to activate properly and scour the tubes efficiently.
Finally, the engineer talked with the plant staff about various evaporator operation basics, including CIP strategy and the effect different settings (and changes to them) have on the evaporation and CIP processes. He recommended further training for the staff to help them better understand how the unit works, troubleshooting techniques and maintenance procedures.