6 replies to this topic

[Art Montemayor]

Mani:

What is "Popcorn" incidence? I suspect you're trying to say you've experience severe corrosion on the shell of your TEMA-type condensers. Is that true?

What is a "Helix Exchanger"? Is it a Spiral heat exchanger - such as the type fabricated by Alfa Laval? If so, then I can confirm that you'll have much reduced stagnant zones in the Spiral model. In fact, this is why this type of exchanger is so efficient. There is no shell side or tube side in a conventional Spiral unit.

Until you identify the cause of your condenser failure, I wouldn't make a general guess on whether changing the type or model of condenser would resolve your problem or not. Your problem may be resolved by a simple material of construction change - but who's to know if you haven't identified the culprit?

More information is certainly needed before making any concrete and intelligent comments.

Art Montemayor

[gvdlans]

My guess is that Mani means a Helixchanger, as made by ABB Lummus Heat Transfer, see http://www.lummusonl...anger/index.htm

A Helixchanger does reduce stagnant zones as compared to normal S&T baffled exchanger. It is often possible to convert a conventional S&T exchanger into a Helixchanger.
I suggest you contact ABB LHT directly to ask whether the Helixchanger offers any advantages in your specific case. You can contact them via the above mentioned website.

[Art Montemayor]

Guido:

I agree with your thinking. Mani is obviously looking at an efficient design of a Lummus Helixchanger. If Mani is reading this, I would note the following for his interest:

1. The Helixchanger is a proprietary design; only Lummus ABB has total control on the special design and rating relationships surrounding this type of heat exchanger. This is a CLOSED ARCHITECTURE type of technology - sort of like an Apple computer. The user has no knowledge or has no capability of obtaining the design and fabrication criteria and know-how. The user is subject to 100% control of the know-how being in the hands of Lummus ABB. This is a very touchy and controversial subject. Any repairs, modifications, or ratings are controlled and done solely by Lummus ABB - no one else has the capability to do this. Therefore, the prices and timing for doing these things are all controlled by Lummus ABB. You cannot rate or calculate this exchanger using the standard algorithms used in HTRI and other software.

2. The possibility of this configuration being efficiently applicable to a vapor condensing duty is subject to the owner's (Lummus) answering all these questions. I kinda doubt it, but I could certainly be wrong since I know little or nothing of the total technology employed.

3. Any conventional maintainance and repairs are certainly going to be subject to Lummus being involved in some way or other -- this is another cost item that isn't discussed for obvious reasons.

4. The design certainly stands to be more efficient than conventional TEMA type exchangers. However, note that the baffle design is very special and the technique to design and fabricate them is very special as well. The mechanical fabrication setup to cut, shape, and drill these baffles is going to involve some tooling-up that possible can't be handled on a local basis. Again, this is one of the hidden prices (or trade-offs) you have to pay when you "lock-in" into a proprietary design that is "closed" to everyone except the designer-fabricator.

I like the design; it is obvious that it avoids many failings in the shell side design of conventional heat exchangers. I don't believe I could justify its application in many instances because of the "closed architecture". In other words, I couldn't go out for competitive bids on maintenance or repairs - or replacement - in the future. I would be totally under the control of what Lummus ABB would charge at that specific time in history - something that many plant owners won't tolerate.

Art Montemayor

Mani, Gents,

Perhaps there is an alternative for you to consider.

Shell Global Solutions has developed new shell & tube heat exchanger technology called EMbaffle Technology. By using expanded metal to replace the normally used plate in conventional technology several benefits can be achieved (shell-side):

- Low pressure drop,
- Increased thermal performance,
- Significant weight reduction
- Uniform velocity & flow in the shell,
- No tube vibration,
- No stagnant zones,
- Can be calculated in HTRI ver. 4.0 +SP1, commercially available software,
- Commercially competitive with conventional technology, in larger exchangers and exchangers with high alloy materials it is significantly cheaper.

If your interested to learn more about this technology please feel free to contact me on George.G.Anderson@shell.com.