Reduction of milk fouling inside gasketed plate heat exchanger using nano-coatings

Fouling inside gasketed plate heat exchangers used in milk production has been reduced using nano-composites coatings. An antifouling coating with low surface energy (low wettability) led to a hydrophobic and oleophobic effect. Test facilities were constructed by the Institute of New Materials (INM) and Institute of Environmental Process Engineering (IUV), University of Bremen in Germany for the investigation of milk adhesion and the stability of the coatings on rectangular plates and small cylindrical ducts. A number of coatings and surface treatments were tested. Certain polyurethane-coated plates and tubes formed thinner deposit layer compared to standard uncoated stainless steel plates and tubes. The cleaning time for one coated tube was reduced by 80% compared to the standard stainless steel one. A pilot plant including a milk pasteurizer at LUFA Nord-West in Oldenburg-Germany was used for the thermal treatment of whey protein solutions. Plates coated with different nano-composites as well as electropolished plates were installed in the heating section of the pasteurizer. Significant differences were observed between coated and uncoated plates. The coated plates showed reduced deposit buildup in comparison with the uncoated stainless steel plates. Polyurethane-coated plates exhibited the thinnest deposit layer. Electro-polished plates also reduced deposit buildup in comparison to the standard stainless steel plates and were almost comparable to the coated plates. The time required for cleaning in place (CIP) with the coated plates was reduced by 70% compared to standard stainless steel plates.

Research highlights▶ Nanotechnology is used to decrease milk fouling inside gasketed plate heat exchanger. ▶ The nano-coatings with low wettability led to a hydrophobic and oleophobic effect. ▶ Polyurethane-coated plates had the least deposit buildup. ▶ The cleaning time of the coated plates was 70% lower than stainless steel plates.