How to recover heat from Boiler blow-down? 

Tip summary

1. • The boiler blow-down process involves the periodic or continuous removal of water from a boiler to remove accumulated dissolved solids and/or sludge.
   • During the process, water is discharged from the boiler to avoid the negative impacts of dissolved solids or impurities on boiler efficiency and maintenance. However, boiler blow-down wastes energy because the blow-down liquid is at about the same temperature as the steam produced.
   • Much of this heat can be recovered by routing the blow down liquid through a heat exchanger that preheats the boiler’s make-up water.
   • The recovered heat can be used to preheat boiler make-up water before it enters the de-aerator, and for low-pressure steam to heat water inside the de-aerator, which reduces the cost to run the de-aerator and improves overall boiler efficiency.

Proposed actions

1. • Evaluate the amount of heat in your bow-down stream.
   • Evaluate the amount of heat recovered in case of Preheating BFW before de-aerator.
   • Evaluate the economics of the required changes.

Economics

1. • Medium cost opportunity with a good ROI.

Savings

1. • Estimated energy savings range: 2-3% of boiler energy use.
   • Decrease equivalent amount of boiler load and decrease CO2 emissions accordingly to save the environment.

Conclusion

1. • Blow-down heat recovery: savings of 2% of boiler energy use.
   • Please share this tip with others to share knowledge and increase energy efficiency awareness.
   • Please contact me for any advice or support about this issue or other energy management issues.

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