How do you design a heater for a crystallizing or heavily fouling service?

Design principles: maximize velocity (2-3 m/s minimum) to reduce boundary layer and shear deposits, use smooth tubes without enhancement, design for easy cleaning (removable bundle, straight tubes), include adequate fouling margin without excessive oversizing (which reduces velocity), consider scraped surface exchangers for severe cases. Materials: smooth finishes, consider PTFE-lined tubes. Operation: maintain velocity during turndown, implement online cleaning if possible (pigging, thermal shock). Critical heat flux must avoid surface temperatures causing precipitation.