How Heat Recovery From Boiler Blowdown Works
Heat can be recovered from boiler blowdown by using a heat exchanger to preheat boiler makeup water [S1].
Temperature Range of Blowdown Heat Sources
Recovering heat from flue gas, drained water, and exhaust steam which are discharged in power plants by organic Rankine cycles (ORCs) to generate power is an efficient approach to reduce fossil fuel consumption and greenhouse gas emissions. This chapter proposes conceptual ORC systems for heat recovery of drain from continuous blowdown systems, exhaust flue gas from boilers, and exhaust steam from turbines. The waste heat source temperatures range from 30 to 200°C [S3].
Program Context for Blowdown Heat Recovery
Install a condensing economizer. Use feedwater economizers for waste heat recovery. Minimize boiler blowdown. Recover heat from boiler blowdown. Replace pressure-reducing valves with backpressure turbogenerators. Use low-grade waste steam to power absorption chillers. Upgrade boilers with energy-efficient burners. Improve boiler's combustion efficiency [S5].
Sample Handling Note
Real boiler feedwater and blowdown were sampled from a full-scale industrial plant in Qatar. The water samples were characterized upon receipt and stored at 4 °C to avoid changes in chemical composition [S2].