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BLOWDOWN HEAT RECOVERY - "The Energy Tank"

The BHR heat recovery system works on the principles of collecting flash steam normally sent to atmosphere during boiler blowdown cycles and retaining the remaining hot water in a closed system for transferring to cooler make-up water.

In steam operations variable make-up water quantities are required to replace the steam consumed in the relative processes. Make-up water is significantly cooler than the boiler feedwater or boiler water temperature as it comes from well(s) or municipal supplies. As a result, there is the potential to transfer heat from a hot volume of water to the incoming make-up.

During boiler blowdown cycles, some of the hot water in the boiler is removed to deconcentrate the remaining boiler water and reduce the scale-forming tendency. This water, at the boiler's temperature and pressure, when released to atmosphere or a vented vessel, generates a large plume of steam, typically called "flash steam". This flash steam contains a total of 1,150 Btus of energy plus pure water. Being released from a higher pressure, there is force associated with it to drive it into another water source.

In other heat recovery processes, the hot water is routed through a heat exchanger. This is reasonably effective, but if make-up is not entering at the time of blowdown, excess energy can still be lost.

In the BHR process, flash steam is released into the boiler feedwater or vented condensate receiver / make-up tank, below the water level to recover the thermal energy and water. This steam is normally lost to atmosphere.

Once flash steam has been released, the remaining boiler blowdown volume is reducing in mass and temperature. The remaining blowdown water is typically around 212oF (100oC), the temperature at which water boils at atmospheric pressure. This volume of water, retained in the storage section of the BHR vessel, can transfer its' heat to a cooler source through a simple heat exchange process. This cools the blowdown losses further and recovers the lost energy in the boiler make-up water system.

By recovering as much flash steam energy as possible and removing the additional heat from the bulk blowdown water, the costs associated with the necessary blowdown process can be substantially reduced.

This process can be further extended to provide additional heating to the boiler feedwater through circulating the feedwater through the top section of the vessel where there is a steam space, thus collecting additional thermal energy. This latter application is more effective in systems that do not have a deaerating heater system.

CASE SUMMARY DATA:

psig Make-upTemp.Before Make-upTemp.After AnnualSavings Case #1 85 73 140 $12,500 Case #2 105 72 101 $9,400 Case #3 13 55 115 $11,900 Case #4 13 60 110 $10,200 Case #5 100&13 60 100 $17,000

Note: Flash steam recovered displaces steam that was normally produced to preheat water. Drain temperatures in all cases range between 70 - 100°F

BHR PRODUCT SELECTION

BHR-15		Non-registered systems Less than 15 psig operation Up to 200 BHP
BHR-150		CSA B51-03 Registered Flash Chamber 150 BHP or less for Firetube/Water Tube boilers 300 BHP or less for Coil Tube/Low Mass boilers
BHR-250HM		CSA B51-03 Registered Pressure Vessel 300 BHP or less for Fire Tube / Water Tube boilers 600 BHP or less for Coil Tube / Low Mass boilers
BHR-1000HM		CSA B51-03 Registered Pressure Vessel 1000 BHP or less systems
BHR-100KHM		CSA B51-03 Registered Pressure Vessel 100,000 #/Hr Steam production or less systems
SPECIAL DESIGN		CSA B51-03 Registered Pressure Vessel S ite specific based on boiler size