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Posted by Ronald Messen on March 23, 2005 at 08:28:50:
We are looking at installing a CHX condensing heat exchanger to heat demineralized water using boiler flue gas. Web site information on the heat exchanger is at www.chxheat.com. The tubes are 90/10 CuNi and we are concerned about potential copper dissolution and/or corrosion from the demin water resulting in copper deposition in the 1500 psig boiler. We do know of problems of this nature coming from HPFW heaters, however, it is our understanding that the copper comes from the steam side of the heater due to amines in the steam and not from the water side. We will be heating the demin water from 50-195F. Water velocity through the tubes is about 2 ft/sec. The flue gas on the shell side will enter at 400F and exit at 180F. There are CHX units that have been in service for 20 years heating zeolite softened water to 200F with no reported copper deposition problems in the boiler, however, these boilers operate at only 300 psig. Should we be concerned? Does anyone know of HPFW or LPFW heaters with this construction heating demin water that do not have waterside corrosion?
Sure could use some concrete information (papers, where to look, etc.) and references where 90/10 is working or not working.
rmessen@steamplantsystems.com