What are the design challenges for evaporators handling polymerizing or heat-sensitive materials?

Challenges: thermal degradation at high temperatures requires vacuum operation and short residence time, fouling from polymer formation on hot surfaces, high viscosity at concentrated conditions affects heat transfer and flow. Solutions: falling film or agitated thin film evaporators (short contact time, thin films), precise temperature control (avoid hot spots), large temperature driving force not possible (limited steam temperature), and frequent cleaning requirements. Consider materials: smooth surfaces, polished finishes, and easy-clean designs. Process simulation must account for rheology changes.