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Extracting bundle of floating head heat exchanger
3

Extracting bundle of floating head heat exchanger

Extracting bundle of floating head heat exchanger

(OP)
Dear All,
we are facing the problem that we can't remove the bundle of our horizontal shell&tube heat exchanger. Weight of bundle is 9t. Design floating head (drawing attached).
Problem: hx has severe fouling and is leaking. Leaks are expected to be caused by uneven thermal expansion due to debris collected between the baffle plates and reducing heat transfer (pic), mechanical stress as we have non corrosive fluids (hydrocarbons).

Assumed reason that bundle stuck in the shell:
Solids (coke) has has settled down at the botom of the shell between the baffle plates (high and tolerance of baffle plates to shell is to small. Bundle can't be moved at all.
We tried to pull with 16 t forklift, used hydraulic jack at floating end to push it and to break it loose - no success. There might be also a deformation of the shell due to uneven heat distribution since we expect a lot of residue (coke - pic is from different unit) has settled at the bottom so free tubes have a different thermal expansion than the covered tubes.Chemicals doesn't work as coke is quite inert to most common used chemicals

We will try once again with larger hydraulic jacks to break the bundle loose and then pull (see right side of marked drawing). If that fails we will need to cut the shell. Red marked cutting of a window is not suitable acc to the vendor as the shell will collapse once the section is welded back (heat impact and shrinking - many attempts failed with other clients). They agreed to follow the green marked strategy to cut the shell in 3 pieces. But even then rewelding will be a challenge. Please note that only the pic with tubesheet (leaks) is the particular unit. The other pics are from an other unit but we were able to extract the bundle. Any suggestion? Thanks in advance

RE: Extracting bundle of floating head heat exchanger

Hi,
Let you try ultra high pressure cleaning , you can use the nozzles at the bottom of the HX to introduce the gun and the hose.

Pierre

RE: Extracting bundle of floating head heat exchanger

(OP)
Pierre, we use normally 15000 PSI hydro jetting but you can't clean the shell side without extracting the bundle first. You would only reach the 1st baffle plate section. The debris is basically like hard coal.

RE: Extracting bundle of floating head heat exchanger

Reminds me of Hell on Earth days at my first job 35years ago with maintenance crews screaming blue murder having to deal with bad actors in the plant during an outage - blocked heat exchangers, tripped compressors, DEG, furnace explosions. Those were happy days. Good luck with the hydraulic jacks, Stefan - SAFETY FIRST. Looks like a TEMA AET HX.

RE: Extracting bundle of floating head heat exchanger

So what can you remove?

Can you remove the whole thing or at that second set of flanges?

Can you drill as et of 1" holes and add screwed in nozzles to jet out coke or maybe even a set of say 4" coupons to get some mechanical cleaners in there. if you do this just in front of where the tube supports / baffle plates are would be a good place to start.

Flood the shell with lubricating oil (thin) and let it soak in for a while?

whatever you do please let us know how it goes - looks errr "interesting".

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Extracting bundle of floating head heat exchanger

(OP)
Hi George, lol.......thanks for the your encouraging comment. Yeah it is still the rest of the coke we produce 2 years ago and lst year when the EDG failed to kick in after power failure. Shutdown since January......Even if I manage to pull the bundle I still have to find the cause of the > 13 leaks and how to fix it.

RE: Extracting bundle of floating head heat exchanger

(OP)
Ok LittleInch some pics as fun part even though I still hv no idea how to deal with it. I soaked with diesel, no success, I used chainblocks and forklift to pull with an impact but not 1 mm moved.I used 160 t crane as fix point and a 16 t forklift.......no chance. The coke residue basically were up to 20 micron fine solids which agglomerated when solvent was removed and is became solid rock. Hydro jetting an drilling was necessary for the tubes. Some tubes took hours to clear. But now I need to get the bundle out to clean the shellside and investigate the cause of damage. The attached pics are basicall the downstream hx which we were able to pull. Enjoy the pics.........
Btw. I was thinking of putting it vertically on the tube sheet and pull the casing like a sleeve just to break it loose. But it is also an expensive job as eqipment etc is difficult to get here in Batam island. It is also not the safest way to stand it up.
This was the first trial to pull and set it on the scafflolding

This was second attempt with tightening the strut bolts and press it into the shell (from floating end). 4x4 was bent and we used small hydraulic jack....Failed

This is a leak and it looks tube is torn on the circumference about 270 Deg. Th end shows the coke blocking the tube. Please note, this is 25.4 x 2 mm SA179 and we hv no corrosive fluids and pressure is below 6 bar.
So it can only be thermal stress due to expansion problems ..

RE: Extracting bundle of floating head heat exchanger

Can you roll it along its axis through 180 degrees?

Then hammer the daylights out of what is now the roof? Basically use its own weight to peel it off the surface just enough to pull it out?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Extracting bundle of floating head heat exchanger

(OP)
I was thinking about it too but such rolling unit is probably impossible to get here beside the fact that I rather think its a mechanical problem with the baffle plates and a deformation of the shell or bundle.

RE: Extracting bundle of floating head heat exchanger

Can't you lay it on some large timbers where you have no nozzles around the circumference and just roll it over using a crane or may a dozen people and some wedges?

It probably is a mechanical fit issue, but worth a try to use its own weight to free it from the surface tension and adhesion.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Extracting bundle of floating head heat exchanger

(OP)
Well, not easy but before cutting we might need to look into it again. An island is always an issue for equipment supply

RE: Extracting bundle of floating head heat exchanger

Nothing lasts forever ....

I suggest that you perform a cost study and contact a TEMA fabricator about a complete HX replacement or retain the channel and consider a replacement of only the bundle and the far side head

If you are forced to chose between replacement of the entire bundle or performing extensive tube cleaning, replacement and repair, then the cost of complete replacement may not be much different.

Bundle replacement also has the benefit and peace of mind of a brand new unit and the assurance that you will not find yourself in the same clogging predicament a year of two from now!!

There may also be some benefits from some design improvements made to a replacement unit (larger tube spacing or a different tube pattern ?) Perhaps even some ports added to the shell for periodic spray clean out ??

Oooops ... I forgot .... your boss just said that there will be no HX replacements !!! ..... Why ?.... Because there is no money in the budget and he said so !!!

Please keep us in the loop and tell us of your final fix

MJCronin
Sr. Process Engineer

RE: Extracting bundle of floating head heat exchanger

One possible approach is to attach vibrators to the tube sheet and saturate the deposits with a penetrating oil (oil and diesel mixture). The idea is to get the solid deposits to fluidize. Pull periodically, not constantly, until things break loose. This will take some time. When you get some movement, it is often best to alternately push then pull, so you do not keep compacting the deposits.

RE: Extracting bundle of floating head heat exchanger

(OP)
Thnks Compositepro,
Such equipment is not available here especially during covid logitic also difficult.

RE: Extracting bundle of floating head heat exchanger

Company managers at my old plant, after some cases of equipment thermal failure due to lack of cooling water resulting from failure of emergency DEG to start up on total power failure, decided to increase the frequency of simulated power failure test runs of the DEG to get better assurance that the DEG wont fail to start on power failure again. Seemed to have worked. The emergency DEG unit seemed to be almost permanently manned by a few mechanical and electrical maintenance men.

RE: Extracting bundle of floating head heat exchanger

(OP)
Hi MJCronin,

Yes new unit but..........as you know
pipe material from Japan, Korea or Europe 2-3 months ex works
building it 3 months...........No budget ..no time either. So need to get plant running by repairing and replace unit asap.

RE: Extracting bundle of floating head heat exchanger

(OP)
George, it was an internal issue knowing that the EDG does not kick in in auto mode due to some MCC issues but not informing and rectifying the problem.

RE: Extracting bundle of floating head heat exchanger

(OP)
Update on cleaning process Blue tube have been found leaking
Red tubes are blocked and need manual drilling. Hydrojetting 15000 psi cant get it out
1. pass is solvent vapor in tubes - 2. pass is condensate (last 4 bottom rows).

Will take another week to get it cleaned in the tube side.



RE: Extracting bundle of floating head heat exchanger

Stefan,

Are there any higher hydrojet pressures available on your island? 15,000 psi is low for hard, asphalty deposits. I’m not surprised it is ineffective. You would be better served with 40k, preferably 55k lancing.

RE: Extracting bundle of floating head heat exchanger

(OP)
TiCl4, unfortunately not. And during covid is is all more complicated to get things in and out. Have you had experience with 40k pressure?

RE: Extracting bundle of floating head heat exchanger

Stefan,

Yes, we use 20k and 40k regularly here for cleaning polymer reactors and Hx tubes. Pressures below 13-15k barely do anything to clean hard polymers off the metal surfaces. The cleaning is done by a professional external company - I do not recommend you taking a "do it yourself" approach when using high pressure water cleaning that is outside your normal area of expertise.

I’ve also used 55k to clean a styrene storage tank - polystyrene buildup is as hard as a rock and chips away like glass. That was cleaning with a hand-operated wand, though - I’m not sure if Hx cleaning is done with 55k.

Ultimately, I think MJCronin is right. I wish you the best, but you I suggest you start collecting design data/quotes for a new unit.

RE: Extracting bundle of floating head heat exchanger

When you HP hyro-lance a HX make very sure that the wand is not inserted or removed from the tube with pressure on. you will peel the tube ends right out of the tubesheets.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

RE: Extracting bundle of floating head heat exchanger

But have you managed to get it out of the shell yet?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Extracting bundle of floating head heat exchanger

(OP)
Thanks TiCl4, I am not experienced with such high pressure using in hx tubes since they are only 2 mm thick. A straight jet nozzle will remove any hard coking but using a polishing nozzle(under certain angle cleaning the wall itself) might cause damage to the tube itself. We will try to find a service company to try but it's Batam lol........

RE: Extracting bundle of floating head heat exchanger

(OP)
EdStainless, we use service company they have experience so that risk is minimized but yeah, good to know that issue since Indonesia does not have always skilled workers on such equipment. Thanks for yr input

RE: Extracting bundle of floating head heat exchanger

(OP)
LittleInch, no progress yet. We now try for the last time to make a structure for a stronger hydraulic jack (50t) and tray again to break it loose. I feel the problem is not so much the coke at the bottom of the shell as it turned into hard coke so it is not sticky but the main issue might be the jammed bundle due to the tight baffle plates. Bundle or shell might have experienced deformation. If this fails........well cutting the shell will be the last resort with new headache to reassemble later..

RE: Extracting bundle of floating head heat exchanger

Please keep us informed by posting more pictures of your progress and your final solution.

Please respect us by keeping us in the thread and leaving information that others will benefit from

Thank you and Best Regards ....

MJCronin
Sr. Process Engineer

RE: Extracting bundle of floating head heat exchanger

Try to hang your shell with a crane and take proffit of the weight of the tubes bundle maybe it works!

luis

RE: Extracting bundle of floating head heat exchanger

(OP)
0707
Already considered but as the 16 t forklift did not work at all, the 9 t bundle will not help much especially crane costs USD 2000/day
I will go with hydraulic jack 50 t and support-frame and will push it from the floating head side. Once it can be moved 100-200 mm then we can pull it. But anyway....this is just the beginning. We will have to clean the bundle and investigate the cause of the leaks (so far 23). Anyone has an idea what can cause such leak as shown in pic? Pressure not exceeding 9 bar. Tubes are 25.4 x 2 mm SA 179
This is just 1 pic with left side large hole.
I am still thinking of mech. stress due to uneven thermal expansion but side walls are looking like overpressure inside of tube. Also leaks happened almost same time. Problem was only recognized when level of 1. column could not be maintained but level of 2. column increased. That indicated the leakage of more than 1 0r 2 tubes. (Still need to check trends which might identify wrong operation)

RE: Extracting bundle of floating head heat exchanger

Corrosion can be due to localized overheating by uneven thermal expansion caused by the coke fouling. Wish you good luck|

luis

RE: Extracting bundle of floating head heat exchanger

(OP)
Thanks Pierre,

Right now all is difficult since we were unable to generate revenue since 2 years. We are bleeding due to some design faults.

RE: Extracting bundle of floating head heat exchanger

(OP)
One of the problem seems to be obvious at the 3rd unit we could actually pull. The baffle plates were made with too small tolerances. The shell has a light deformation on the top where the lifting lug is welded at the shell. When the manufacturer installed the bundle, the baffle plates were already bent (Easy to see since the direction shows it)





Lesson learnt. Keep 3 mm gap between shell and baffle plate. At least if you run with products which require regular cleaning of shell side.

RE: Extracting bundle of floating head heat exchanger

3
(OP)
So here we go, finally I had time to loosen up the bundles. How did we do it?
1. Pulling didn't work so I decided to push it out with a 100t hydraulic jack
2. Built a structure with a 20 mm plate to protect the tube sheet, and a reinforced 24 mm plate as counter part.
3. Used 8 long stut bolts to balance the forces on the shell flange
5. Welded a support on the plate to support the 30 kg jack
6. Installed marker for the progress of movement
7. ....starting pumping up. Once the pressure was to high the bundle made a 20mm jump and was freed.

Costs:
Steel plates from junkyard incl cutting, drilling, stut bolts, u chanel, welding, rental jack: ~ USD 800

Need retubing now since many damaged tubes can be seen. Corrosion might be the reason due to chem reaction of solvent. Acidity might have not been considered correctly in the design of the heat exchangers. Need to send samples to metallurgic lab to confirm.



Video: https://files.engineering.com/getfile.aspx?folder=...

RE: Extracting bundle of floating head heat exchanger

(OP)



RE: Extracting bundle of floating head heat exchanger

Hi,
Good job and thanks for sharing your progress and video.
Bagus,bagus.
Pierre

RE: Extracting bundle of floating head heat exchanger

I used to work in a plant that had similar problems with coke-like deposits accumulating in the shell side. When cleaning was necessary, we sent the exchangers to to be "baked-out". This was done in an exchanger service shop that had an oven for this specific purpose. For coke-like deposits, which seize the tube bundle to the shell, this is a practical and cost-effective solution.

RE: Extracting bundle of floating head heat exchanger

Stefan - to clarify, you used a hydraulic jack to push the bundle towards the shell side to loosen it, and after it moved you were then able to freely pull it all the way out?

RE: Extracting bundle of floating head heat exchanger

(OP)
TiCl4, I havn't pulled the bundles yet but it will be done this week. It is loose and easy to pull now. It has tremendous coke deposits and was actually cemented in the shell.

Don1980. Unfortunately we do not have such facilities here in Batam and it requires a high temperature I am sure.

RE: Extracting bundle of floating head heat exchanger

Stefan2211,

Thank you for sharing your field experience and detailed reasoning in solving this challenging HX problem.

Your extra effort by completion of this thread certainly helps us all ..

Thanks again

MJCronin

MJCronin
Sr. Process Engineer

RE: Extracting bundle of floating head heat exchanger

(OP)
I will provide more insight once we have pulled the bundles and cleaned up.
Another unit will be inspected the next 3 days with Eddy Current to check the wall thickness. Unfortunately we do not have any test rings for hydro test. I definitely would always buy optional test rings if you have corrosive or critical fluids that can cause tube damages. It looks like my assumption of mechanical failure might be wrong and we really created a corrosive environment inside due to operation conditions.

RE: Extracting bundle of floating head heat exchanger

(OP)
HELLLLLPPPPPPP!!!!
Guys out there, I now need your input. My maintenance managed to damage 2 expansion bellows which are installed between floating outlet and end cap. Pic attached...
Right pic shows 6" bellow which is bent as they removed endcap without realizing there is a bellow. Now I need to straighten the bellow to be able to install it again.
Left pic shows 8" bellow (different heat exchanger) which was deformed (now 30 mm longer) during a hydro test. They did not restrict the bellow movement. So I need to get it back to original length.
Bellows are SS316 , the 6" bellow is made of 2 ply 0.6mm = 1.2 mm
8" is made 3 x 0.6 = 1.8mm
Buying new ones is not an option right now as it will take min 8 weeks
I am planning to heat the bellow with gas torch and carefully try to adjust them and replace within the next 3 months with new ones

Any comments? Thanks guys out there.

RE: Extracting bundle of floating head heat exchanger

In the future I would suggest install a spare heat exchanger and clean the other units more often. With the spare unit you can rotate the other units for cleaning. The other possibility is to replace shell and tube exchangers with plate exchangers that can be dismantled easier for cleaning. Another idea would be to install connection points and valving on in and out piping so that the exchanger can be flushed with cleaning fluid before it gets too dirty. Install a differential pressure gauge on in and out piping to show when the exchanger is fowling up.

RE: Extracting bundle of floating head heat exchanger

(OP)
Dear Quadtracker,

We have considered all these option but due to our product itself and the available space it looks like regularly cleaning is the only way. Larger units with spare heating surface might be an option to prolong the operation time but will be still a major modification.

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