Glycol and Temperature Issues

W Deacon

Anyone have experience with glycol "cooking"?
We have a heat exchanger that a portion may run at 300-350F, the rest at 200-250F or cooler. There is a circulating pump that keeps the water glycol mix flowing at all times, and with a temperature set-point of 160-180F that the total fluid will not exceed.
The engineer is concerned about the glycol molecules that will bump up against the hot (350F) exchanger surface.
I don't see a difference betweeen that and a gas fired boiler, or an automotive cooling system, for that matter.
Can anyone point me in a direction for advice?

Canuck

Hmm - Good Question

Here's my thought process - consider the heating boilers of an older highrise condo or apartment.

I know that when you have a single boiler or bank of heating boilers - fintube style, (like a Raypak or Laars), and you have a single building pump that may be 'wanting' because of age; you sometimes get noise off of the boiler because the water is moving too slowly and therefore heating to the point whereby it starts to create steam.
Conversely, I know that when the pump is good, all systems are OK. I also know that water temperature never gets over 220 deg F. on these boilers/systems, even though stack temperature at the breech may be between 350 - 500 deg F.

Following through to your scenario - the HXC is not unlike the thin walled fintube of the boiler. If within the boiler, the fluid won't heat above 220 deg F with a heat source in excess of 400 deg F (pending pump characteristics), then I can't see any reason that your glycol/water mix would do any different with the 'hot' side at 300-350 deg F.

Drew_2

PG Temps

Our standard Noburst product is good to 250 degrees F with a film temp of 325 Degrees F. The Noburst HD is 325/375.