De-aerator Hammering While Starting BFP

With <...BFP...> undefined it could be any of the following:

• Poor design
• Operating outside the design envelope
• Operating outside the Standard Operating Procedure
• Air in the system where it shouldn't be present
• Pressure bottle fault, such as incorrect charge material or pressure
• Mechanical fault
• Etc.

In any case, it cannot be seen from here. How about hiring someone locally who can see the problems and provide a local insight?

There seems to be a problem with the keyboard used to make the original posting. How about changing it for one that has a full set of working keys?

BFP = boiler feed pump.

If you are getting hammer in the deaerator while swapping pumps it is most likely a controls problem and you are getting excess flow or not enough flow. It could also be due to a pressure drop in the boiler feed allowing hot water in the pipe to flash.

Monitor the levels in the D.A. when swapping to ensure you are not getting surging or raising / dropping the level. Also closely monitor the temperature, if it is flashing you should see a temperature drop in the feedwater.

I shouldn't have to caution you to watch the steam drum levels which could also fluctuate when swapping bfp.

Drew K

Drew K touched on a likely answer: You may be running a higher than design temperature in the deaerator, and when you kick on the second BFP, there is a change in suction pressure, resulting in water flash boiling cavitation. This could actually damage your BFP's, and also the hammering can cause other problems, perhaps with the pipe network by over-stressing the pipes. Perhaps you need to cut down on the heat load to the DA vessel prior to starting the 2nd pump during switch-over. Have you tried simply turning off the 1st BFP before starting the 2nd BFP? Also you need to make sure of how you have the output valves set up to make sure you are not surging the pumps.