Condenser Tubing
Condenser Tubing
(OP)
Our customer has asked us to re-tube their GE steam turbine condenser, replacing the original 2134 1" OD x .049" (18 BWG) Admiralty D Brass tubes with 1" OD 304 Stainless tubes. There is a section of 304 tubes originally installed as a separate cooling section in this unit that uses 1" OD x .028" (22 BWG). I can use this to calculate that the joint strength will be adequate. What would be the significance on heat transfer?





RE: Condenser Tubing
RE: Condenser Tubing
This will let you correct for the change in flow (you need the pump curves) and then estimate the new heat transfer values. We do this for customers all of the time.
Don't try to go back to heat transfer fundamentals, you will not be able to model what is happening in a real condenser.
You didn't say but I presume that they have have bronze tube sheets.
Is this water VERY clean? If not then 304 will not stand up. The tubes in the air removal section may have survived because the rest of the condenser is providing galvanic protection.
You should consider coating the tube sheets to suppress dealloying of them. A high build, 100% solid epoxy system is typically used for this (Plasticor is the very best).
Typically the limit for tube wall when moving from a Cu alloy to a SS is based on vibration. considering the differences in modulus 0.028"aw SS tubes will be stiffer than 0.049"aw brass tubes. It is a safe move that has been done in hundreds of condensers.
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P.E. Metallurgy, Plymouth Tube
RE: Condenser Tubing
The tube change that you desire has been done on steam surface condensers many times. You may want to try to contact another power plant owner who has made these changes for advice
As stated above, there are also some major decisions (expensive) to be made about the tubesheet surface.
You should benchmark the flow and pressure drop, both before and after the retube.
BEWARE OF CHLORIDES ! You should purchase the few available books about condenser design on AMAZON and try to get some of the fine EPRI guidelines published regarding condenser repair.
Purchase the HEI standard also....
MJCronin
Sr. Process Engineer
RE: Condenser Tubing
Thanks to you all for your responses. We are not new to this business and actually re-tubed this identical unit in 1997 and many more since 1980. This unit, like almost all of the condensers and HEX we have re-tubed have following OEM designs. This change is something new here in Alaska. I am familiar with almost every Boiler system and HEX here and none have done this retrofit yet. I appreciate the cautions and will proceed accordingly.
RE: Condenser Tubing
Hire one of them. They are both technically competent and excellent project managers.
But to MJCs comment, if your chlorides ever go above 100ppm or there is any risk of any biofouling 304 will not survive. Trust me on this.
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P.E. Metallurgy, Plymouth Tube
RE: Condenser Tubing
1. You eliminate cooling water side erosion risk
2. you become fully resistant to sulfides (and H2S) in the cooling water
3. the steam side will be fully resistant to ammonia attack and grooving
4. Significantly greater steam impingement erosion resistance
5. No Cu in you cycle water (or cooling water for that matter) (as long as your feedwater heaters are also steel or SS)
Once your cycle side is all ferrous then you can move to Oxygenated treatment systems for boiler corrosion control.
Welcome to the modern world.
Feel free to ask me any condenser tube questions that you have.
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P.E. Metallurgy, Plymouth Tube
RE: Condenser Tubing
RE: Condenser Tubing
SeaCure is a superferritic that was designed for use in seawater cooling applications.
However as metengr points out MIC in fresh water is often a very serious issue. This has destroyed dozens of 304 and 316 condensers over the years, along with Mn related pitting.
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P.E. Metallurgy, Plymouth Tube