Posted by Tony Conner on January 24, 2000 at 11:35:50:
In Reply to: Reverse osmosis posted by Barry Fawcett on January 24, 2000 at 10:01:10:
: We have several process boilers around the country with varying degrees of local water quality. All are seeing less than 5% condensate return. Our chemical guys are trying to sell us on RO based on BTU savings from the surface blowdown. I suspect there is a large difference between theoretical surface blowdown and actual. In my recent posting on "blowdown calculations" one reply said that actual metering had shown somewhat less blowdown than calculated. Any one have experience with RO and process boilers?
The ROs will no doubt significantly reduce CBD. But, they are pricey, and you have to run a good sized pump motor to make these things go, there's a significant amount of reject water, and you may need a storage tank. We installed ROs at a high make-up plant I worked in, (CBD rates dropped to a fraction of previous values) but the justification was high quality water required for a gas turbine & HRSG co-gen set up that was being installed. Post or e-mail me some data on one of your typical plants (boiler pressure, maximum steam load, calculated % CBD, incoming make-up water temperature, & fuel cost ($/million BTU) and I'll run the calculations on a CBD heat recovery heat exchanger, if you're interested. I've seen paybacks in 4 weeks on these installations, depending on fuel costs.