What are the critical design considerations for a waste heat recovery boiler?

Considerations: gas-side fouling (design for cleaning access, soot blowers), acid dew point corrosion (maintain metal temperature above dew point, typically >150C for sulfur-bearing gases), flow distribution (avoid hot spots), thermal shock (startup/shutdown procedures), two-phase stability (adequate circulation ratio, typically >5:1), and blowdown management. Materials selection based on gas composition (sulfidation, carburization). Economizer positioning optimized for heat recovery vs. corrosion risk. Emergency steam dump or bypass for loss of steam demand scenarios.