Heat Exchanger Problem

No experience. But if you know you have a fouling fluid and use inserts, aren't you setting up a maintenance nightmare?

Ordinarily, the fluid with the controlling fluid coefficient is put on the shell side. I would assume this would be your process fluid. Is there a reason this could not be done? Also, have you considered a scraped surface heat exchanger?

Thanks for the responses, hope I can keep a flow for my responses without going all over the board.

bigg

We already have a nightmare with a plate. It does the job, which is the first criteria, but the maintenance is the nightmare.

By removing the plates, each plate has a gasket, and to clean each plate and reassemble them... in the correct order is not very efficient.

With the thinking of a Straight through counter-flow shell and tube (Not a U-Tube), it would be mounted vertical, the tabulators can be pulled, and a brush run through on the tubes. and the buildup drop out the bottom.

See Pictures. As far as the buildup to the tabulators, they can be cleaned periodically, leave it to maintenance discretion.

The product fluid is on the tube side, but we had discussed of running the fluid on the shell side, but with the type of process we are running, the buildup would not allow this.

As far as a scraped surface, it's usually used for high viscous material. I had questioned the Viscosity of the product from the 20 year old data, and sent a sample to our lab for analysis. turns out to be a fraction of it.

We may still try the tabulators.

To match a S&T thermally to a PHE will be challenging. It can require up to 10 times the surface area in S&T to do the same heat transfer. And there is also the temperature approach...the best you can hope for is 10F approach in a S&T. Look at using a spiral plate heat exchanger. They are very good on viscous, debris laden, fouling fluids.

hexguy

Yes, for this application the efficiency is not good for a shell and tube. and a plate is more appropriate. Only looking at the shell and tube to cut down on the maintenance

So, I'm going to running it in my heat exchanger program with the latest viscosity, I feel with the lower cP it's going to creates a turbulent flow in the program, even though the program shows it possible, there is still a chance it could be flawed. It's been known to do that time to time with low flow and a tight temperature differential. (I know what I stated earlier about the program, was hoping the lab showed the viscous was high)

I can get a turbulent flow, with this now said, I still have to deal with the temperature cross over, The thought is hooking a series of shell and tube together, each with its separate cooling supple to avoid temperate cross over.

You should be able to build a 1 tube/1 shell pass exchanger to handle the temperature cross. Depending on temperature and materials, you may need some expansion device. Good luck.

I have experience with fouling flow through a horizontal T&S exchanger.

We incorporated a reversing valve that was activated by a pressure drop sensor.

It required a 4 way valve and a dump to waste drain during back flush.The back flush duration was set by a timer.

This system worked well for many years, extracting 13 Million BTU/Hr from waste water in a dyeing operation.

Thanks, but I don't believe a backflush would work on a plate, it has to be manually addressed.

I'll drop some more mechanical properties on you. The brix is quite high on the product.

Tube-in-tube could give the temperature cross, but would tend to be large and expensive.

Thats correct, and the cost/benefit is what I'm determined now.

This has started me wondering about some alternatives.

What're the working fluids?

Are they Al alloy compatible?

Pressures?

I did the thermodynamics testing and data acquisition on a "new" invention about 25 years ago. It's an alloy extrusion and has impressive heat transfer numbers.

Can't quote 'em now. Passed all the data on to the owners on completion of the tests.

It was for a local company called Thermo Dynamic Industries Pty Ltd.

Looked for a website, but can't find it to direct you to, however, DO know the guy who's boss and can put you in touch if it'll help.

When I was involved it was the start of a very good idea for some applications.

Did some work on adding spiral turbulators into HX tubestacks to increase the heat transfer.

This was on cupro-nickel tubing and had to be careful not to reduce the cross-sectional area too much. Anchoring the little devils was a challenge too. didn't want vibration causing abrasion damage withing the tubes.

Pressure drop was in the order of double, bearing in mind that we were operating at little more than ambient pressures. Increased pressures would reduce the effect.

Be interested to know how you fare with this one.

Cheers,

Stu.

I can answer what I can, but it look like it's not applicable.

and I have to answer ambiguously, it is proprietary information,

What're the working fluids? Product, Pyrolytic Acid, other that that, it proprietary information, Cooling media Water from cooling tower, this summer it got up to 85F, we don't have a problem in the winter.

Are they Al alloy compatible? No

Pressures? about 60 PSI

Thanks for that.

Cheers,

Stu.

Why not just get rid of the plate frame / shell and tube and cooling tower and install a evap condenser type of tower in place of all. Still using the water as your cooling media and you may have room in the tower area for an increased foot print if necessary.

you could install a VFD on the tower to control fluid temperatures, or remove all and install a air over fluid cooler in the tower area with drives on the fans as well.

like to keep the change over under $100,000.

I don't know what you mean by:

and install a evap condenser type of tower in place of all.

Scraped surface heat exchangers might be a better way to go.

Arrange some pilot-scale trials with a vendor using off-spec product, perhaps?

Thanks,

Scrape surface would be considered until the lower cP came back from the lab.

And we are running some trials inhouse to atleast determine a reference.

There some very good heat exchanger manufactures out there that have every good R&D labs in house. Give some of these folks a call and let them give you a hand to come up with a proper solution. Rather then get something from me or someone else that may or may not work for your application.

Darned good advice there.

Vendors are the ones with a vested interest in giving you a solution.

With a budget constraint, not a trivial amount either, solutions that are available and known to work are the most cost effective as they will work...hard to justify the cost of a trial that went wrong even if it could have been less costly, if you get my drift.

Vendors are the ones who have their fingers on/in the extant solutions. They can also come in and look at your set up if they are local.

Phoenix911 has received some excellent suggestions here. This will make him a very informed consumer.

Cool discussion, much enjoyed.

I read your post after what I posted earlier which is inline, yes it is interesting.

Thanks,

I'm not doing this alone, I do have a manufacturer working with me that is a leader in this, but when you have a temperature cross over, low flow and such, it is, as a thermal leader they are admit its difficult.

And some of your responses match their initial ideas. I should have some more information from them next week.

Look it it as brain storming.

I find when an issue like this comes up, the more I understand, the better chances I can come to a solution. I tend to look at cr4 as a resource, arrogant of me..... Maybe. But still a good resource.

So while they are working at one end, I'm working separately. Then we compare and come up with the best solution.

Thanks again.

Perfect.