The yogurt production line renovation of a dairy enterprise adopts our KDP multi-stage food grade plate heat exchanger system. The equipment integrates three independent heat exchange units: the front section uses a large angle corrugated plate to rapidly heat up 4 ℃ refrigerated fresh milk at a rate of 10 ℃/min to avoid protein denaturation; Install turbulence enhanced plates in the middle section to maintain temperature fluctuations of ± 0.3 ℃ under 72 ℃ pasteurization conditions; Innovative application of double wall panel structure in the final stage, achieving complete isolation cooling between 10 ℃ ice water and heat medium. The system uses multi-stage pressure difference control technology to reduce the viscosity loss of fermented milk with 20% solids to below 5% during heat exchange. Combined with the 90 ° quick release flange design of the CIP online cleaning system, the sterilization efficiency reaches 5log microbial inactivation rate, and the risk of cross contamination during equipment product switching is reduced by 99.9%.