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High Dew Point in the gas Furnace

High Dew Point in the gas Furnace

High Dew Point in the gas Furnace

Hi Guys!

I was just curious about how to reduce the dew point in the furnace... Endothermic generator's dew point is as we want. but whenever we checked the furnace dew point, it shows 70 when it's supposed to be 55. We first figured there is water in the endo gas pipes for some reason, even after we drained it out, the dew point never changed...

Does anybody know how to solve this issue?


RE: High Dew Point in the gas Furnace

Air leaks are a major source, or moisture on the surface of incoming product.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

RE: High Dew Point in the gas Furnace

Dear mtnz,

What type of furnace is this?
What is the fuel used?
Does it have BFW lines and generate steam in the convection zone?
What about the location, is it dry or humid?
Lastly, what instrument do you use to measure the dew point?

Answers to the above would lead you to solutions.




RE: High Dew Point in the gas Furnace

Hi Dhurjati,

That is an Endothermic furnace. We had problems with one of our generators so we run 2 furnaces with only 1 generator for a while. We have a problem with harden the parts lately.. They won't get any harden than 40-45 HRC when they need to be 55. We use Endothermic gas and natural gas. When we load the parts, temperature of the furnace drops down to 1200 and until 1450, Nitrogen kicks in. It is an old system (30 years).. The generator has a retort and catalyst in it. So about the location, we have a big door that material handling guys use a lot. So sometimes they keep it open for a while and the furnace area gets really cold. We are also using Super System DP2000 dew point analyzer. The issue we are having is in oil quench furnace.

I have to figure out the problem and solve it because we heat treat 90% of our products. It is basically the biggest operation here. I would appreciate if you can help.


RE: High Dew Point in the gas Furnace

Dear mtnz,

Is the air-gas ratio okay?

Check the below link:


In addition to above, also check if you have filters / coalescers / heaters in the natural gas line upstream to the furnace? If yes, check those. If no, analyse the natural gas for moisture content.

Also check the below link:





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