How do you optimize a crude preheat train in a refinery?

Optimization approach: collect field data (temperatures, flows, pressures), calculate current heat recovery and exchanger duties, identify underperforming exchangers (compare actual vs design U), determine fouling rates and cleaning schedule optimization. Improvements: address severely fouled exchangers first (cleaning or antifoulant), resequence for better temperature approach, consider parallel/series rearrangement, add new exchangers at pinch, install monitoring for fouling detection. Target is maximizing crude inlet temperature to fired heater while minimizing fouling and pressure drop.