A Caloris customer with a whey processing system off of their cheese line requested a service visit to address efficiency issues.
The whey processing system operates 24 hours a day, 6 days a week. Our engineer reviewed their spray dryer, pre-evaporator, hicon and flash cooler to look for opportunities to improve their operation.
He initially noticed a low operating temperature in the first stage of the spray dryer’s external fluid bed. Crystallization occurs at this stage of the dryer and the temperature needed to be raised so it was more aligned with the exhaust temperature coming off of the dryer chamber.
He noticed that the product on the belt at that point of the process was very clumpy and the clumps were still wet in the middle when broken apart. This is a sign that the lactose is not yet in a stable form.
In the next stage of the external fluid bed, the temperature was significantly higher and the powder started to fluidize. While there were still clumps, they broke apart easily and didn’t clump back together when compressed. This signals that the crystallization process is complete.
Visually, it seemed like the whey processing system dryer was one stage behind. Adding heat to the first section of the external fluid bed would allow the product to crystallize more efficiently and prevent clumping on the belt.
Next, our engineer observed that the feed rate to the dryer was less than specified. He observed 47% solids, whereas in 2012, the solids were around 50-51%. To achieve the desired production rate, the feed rate would need to be increased.
No site visit is complete without a search for vacuum leaks and there was evidence of leaks to be found. Neither the pre-evaporator nor hicon could achieve the desired set point. Our engineer found significant vacuum leaks on the lids of both. He also found a vacuum leak on a sight glass on the pre-evaporator that was pulling air bubbles into the COW water.
Another large vacuum leak was located on the vacuum system that connects to the flash cooler. Duct tape around the lids on the flash cooler indicated the staff had implemented temporary patches on still more vacuum leaks. Correcting these vacuum leaks could improve the outlet temperature and therefore the efficiency of the crystallization in the crystallizer tanks.
Our engineer also noticed that the cooling tower didn’t appear to be working efficiently and recommended a more in-depth investigation of that part of the system to determine why. Finally, he noticed that the evaporator instrumentation seemed to display a faulty reading after the vacuum was broken. Recalibrating this instrumentation would be necessary to ensure the readings were accurate. Inaccurate readings can cause plant staff to make changes that are unnecessary and create further issues.
After detailing all of these issues to the customer in his final report, our engineer recommended the plant tackle the vacuum leaks first, to help the current system perform closer to spec. Raising the solids off of the hicon would then allow the dryer to achieve the desired processing rate. Finally, he recommended reconfiguration of the flash cooler away from the evaporator vacuum system to allow better crystallization in the tanks and relieve the loading on the dryer.