Question of the Day: Common Drain

Published by in Academic

Question of the Day:  Common Drain

Question of the Day:  Common Drain

What could happen if a dealkalizer, water softener, and boiler blowdown all share the same drain?

Tags

Category: Academic

5 Answers

Big problem.  I have seen ...

Big problem.  I have seen this too often.  A big scale build up at the point where the flows mix together.

Wow, don't they teach qualitative analysis in chemistry classes anymore?  High alkalinity from the boiler will precipitate the hardness down for the bottom blowdown valve to remove.  Duh!   High alkalinity from the boiler will precipitate the carbonates, hardness and a lot of other things.    Look up lime soda softeners and learn how they work.   Learn about precipitation and why it happens.  Most of all, get off the net and quit asking questions of people who don't know.  Go get a chemistry text book and read it and forget the computer discussions.  This was written about over 100 years ago.  Good grief kids. 

Published by

I agree with David Barter and ...

I agree with David Barter and I add that the boiler blow down water has relatively high pressure, which could block softener's and dealkaliser reject to flow freely, especially if boiler blow down is continuous. In such circumstances the regeneration will fail. 

Published by

The issue here really is one ...

The issue here really is one of Hardness.  The hardness from the regen will precipitate if either the temperature is increased such as from blowdown or the pH or carbonate concentrations are increased .  

The Softener could be combined with the blowdown only if the blowdown was cooled to room temp prior to mixing with the high hardness water form the softener.  this may be done with softened quenching water or exchangers for capture of the heat.

As for the Dealk it depends which type of dealk you are using.  Weak Acid Cation, or Split stream would not cause issues with a softener, however if you are using a Cl Anion and are regenerating with salt and caustic, you could likely have some issues if both systems were to regenerate at the same time. You would have high hardness and high pH/Alkalinity which is a recipe for scale formation and potentially big issues.

another factor to consider would be other flows in the same drain that could be a diluting factor.

 

Hope this helps

Published by

Good question. My immediate ...

Good question. My immediate reaction was it would scale but how are you running your dealkalizer is more the determinant?

Published by

This sounds like a recipe for ...

This sounds like a recipe for a plugged pipe.

Published by