Condenser Designs - Query

eriskay
31st January 2009, 17:52
Has any of the erudite engineering fraternity that populate this great forum ever come across a design of Condenser (Land or Marine) that has two tubeplates at each end, rather than the conventional one tubleplate? Apparently the two tubeplates had a gap, say 12mm / 1/2 inch, between them, and I understand the concept was that in the event of a tube leak the coolant (seawater) found its way down between the tubeplates where it was led away to safe drainage/recovery, rather than find its way back into the condensate where, of course, it was unwelcome.

I received an enquiry today in this regard from Australia, where the enquirer claims my Company supplied this Condenser design to them back in the early 1970s. Having been with the Company since 1968, and having never heard of or experienced such a design , I think he is mistaken, but thought I would put it to a more learned audience - that means YOU ! Hope to hear from someone in due course that can throw some light on the matter.

Angus

davetodd
31st January 2009, 22:50
Angus
I had to read this post more than once in my attempt to understand the concept.
Presumably the pressure in the steam/condensate space of the condenser is lower than the pressure of the coolant in the tube spaces.
If a tube leaks within the steam/condensate space, why would the coolant go anywhere but into the steam/condesate space? How can the double tube plate cavity attract the coolant??
Further, I would be interested in the method of sealing the tubes in the inner plate of the two tubeplates.
Did your contact produce any drawings or sketches by chance?(EEK)
Best Regards
Dave

eriskay
31st January 2009, 23:14
Dave :

You have raised the very same points I did earlier today with the person who passed this to me. I cannot envisage what is going on here, to be honest, and you yourself highlighted the improbability of such a design. No, there is no supporting documentation, sketch, etc, I also made that point that without something to work on there was not much to comment about. Most condensers we work with operate with a fairly high vacuum on the condensate side, and as you point out, it would be expected that the seawater coolant passing through the tube bundle would be delivered from the circulating pump at anthing from 1 bar g to 4 bar g, therefore any leakage path is only heading in one direction with that differential, innit? :-(

If I learn any more I will put up details. Considering this installation dates back to the early 70s, allegedly, it's also very strange that questions on the system design and functionality should be getting asked now - 30 years on !

davetodd
31st January 2009, 23:20
Very baffling Angus.
The only other thought I had was if the process was reversed!!
Pass the steam through the tube and coolant outside the tube!
An engineers nightmare to say the least.
regards
Dave

david freeman
1st February 2009, 11:39
Has any of the erudite engineering fraternity that populate this great forum ever come across a design of Condenser (Land or Marine) that has two tubeplates at each end, rather than the conventional one tubleplate? Apparently the two tubeplates had a gap, say 12mm / 1/2 inch, between them, and I understand the concept was that in the event of a tube leak the coolant (seawater) found its way down between the tubeplates where it was led away to safe drainage/recovery, rather than find its way back into the condensate where, of course, it was unwelcome.


Angus
Baffled and perplexed-but here goes! In steam plant if one had boiler water/condensate under pressure passing through various heat exchangers on its way to the deaerator, and one such heat exchanger had water say from a primary feed system for firetube/ rather than a water tube boiler e.g. deck steam returns from a low pressure steam system. Then maybe a steam to steam condensate interchange may take place, and hence contamination.: This is highly unlikely in my experience as most low pressure/wet steam cycles for deck and domestic steam were separate and completely free from the High pressure steam cycles required for water tube boilers of over 440psi 600Degrees Fahrenheit superheat. As you say on the sight what is going on is the design a dream?

chadburn
1st February 2009, 14:26
Seems a bit of a belt and braces set up, has it anything to do with L.P. steam side of a Nuclear Plant.

eriskay
1st February 2009, 15:37
Thanks for all comments albeit, like myself, no one appears to recognise or have any experience of the subject design. I will endeavour to get some further details or, better still, drawing/sketch/specification/O & M Extract, to see if this will give us something better to work on.

I would - 99% - rule out the Dave (Todd) hypothesis, the only process where I have any experience of the thermal heat exchange being 'reversed' is on TCD distillation plant, and in that case it is an intrinsic part of that process design whereas it would not be applicable or relevant on conventional heat exchanger equipment.

Agree with David (Freeman) observation regarding the essential and normal philosophy of separating the differing steam quality systems, so would presume this is not a factor.


Chadburn's query re nuclear plant process - haven't a clue. However, would go along with the 'belt and braces' comment. After all, although we may have all experienced the odd tube leakage problem on conventional heat exchangers, the reasons for these are well known and chronicled, and certainly not the basis of evolving a new and rather complicated design that would appear to offer more potential problems than solutions.

Annoying, eh?

surfaceblow
2nd February 2009, 21:01
After thinking about the description of the condenser design for a while I could not think of any with two tube sheets with a tale tell hole between them. But it could be an earlier design of the condenser that did have one thick tube sheet that moved for thermal expansion. The thicker movable end had two o rings in-between the two o rings there was a opening on the bottom that was the tell tale if the water box o ring failed water would leak out from the opening. If the inner o ring failed than you will have an air leak and have a loss of vacuum. This design was a little bit better than the packing on the outlet end of the tubes. The tube sheets were fixed and the tubes moved in the packing glands. I did not like the job of repacking the tubes.

The best design was where the tubes had a bow to them and was the temperature increased the tube would straighten.

eriskay
6th February 2009, 17:33
Surfaceblow :

Thanks for response. Yes, I well recall the old screwed ferrules and tape packing design for tube-end sealing - a laborious and tedious job if having to do a whole Condenser, which was often the case! The lot of a hard-done-by apprentice and often used by foremen and chargehands as 'punishment' for apprentices who had made a bad job of scraping white metal bearings or some other moreinteresting line of activity. However, they did allow free expansion and prevented 'creeping', but tended to be maintenance-intensive.

The tubeplates in question are apparently set with a spacing of around half an inch (12.5mm), or so I was told. As opposed to a tell-tale hole arrangement. I had hoped to try and get further details from the enquirer but am off work presently and unable to do so until I get back behind my desk.

Regards and Thanks !

Derek Roger
6th February 2009, 18:52
Angus the way you describe the double tube plate at each end may have some merit.
As I understand you there is a 12mm void space between the plates .
If there is a water leak at the connections between the outer tube place and expanded / rolled tube then the water would leak into the void and not contaminate the condensate .
Similarily if there is a leak between the expanded tube and inner end plate then air would be drawn into the condenser from the void space and not salt water ; thereby avoiding salt water contamination .

However if the leak is in the tube itself between the two inner end plates ( pinhole or similar errosion ) then the condensate would become contaminated in any event .
An interesting concept and certainly would prevent salt contamination due to leakage between tubes and end plates .

Derek ( Comments please ?)

chadburn
7th February 2009, 10:51
Derek, that is why I wondered as to whether there was any Radio-active source involved, as to the old Ferrule Condenser's they were indeed hard work especially if the square or slot ferrule's were rotten, after a re-tube it was then a matter of wrapping the packing cord around a bit of tongue and groove to get the required length and then cut along the groove before soaking them in hot tallow before repacking the faceplate with a bit of "modified" old condenser tube fitted with a file handle. Where I served my time it was not considered to be a "defaulters" job as indicated by Eriskay as some skill was required to chisel the broken screw ferrules out without costly damage to the faceplate as well as a job well done when it was boxed up and tested without showing any leaks and all the ferrules were the same "height" off the faceplate rather than higgaldy piggly as one Engineer I know use to say!!

davetodd
7th February 2009, 11:25
Geordie Chief
Your comments bring back memories of cold winters, sat on a board at one end of the condenser while your "oppo" sat at the other and usually in darkness on a "dead ship" fit-out.
A carbide lamp poked down one end of a tube was your guide to get the correct one before tightening up. Didn't need that when knocking the tubes out, but had to duck now and then!
Team work was essential, not a defaulters job as you rightly say.
The job was ours from start to finish.
Strip down, remove tubes,transport tubes to yard, clean tubes in parrafin bath and return tubes to ship.
Remove both tube plates, clean internals, re-assemble, re-tube and repack (early method was with cord and stemming tools until patent packing sleeves came in)
The ferrules with the square end I prefered over the slotted easy break type.
Pressure test to foreman's satisfaction.
A long and tedious job but with satisfaction at the end. Used to get 2/6 each on complet ion if we passed the test first time.
Thanks for the memories.(Thumb)
Dave

chadburn
7th February 2009, 16:34
In-H- bred "Mickey Mouser's" don't have such memories Dave. I was on some very early Steam Jobs and you certainly learnt chiselling skills when trying to get the broken ferrules out without damaging the thread in the faceplate's

japottinger
7th February 2009, 18:01
Anyone had experience of putting in sawdust to try and seal a tube leak?
I spent a year of my eng. app. at Scotts' in Greenock on the surface table marking off. One job was marking off ALL the holes on a condenser plate,, I will try and recall, four dabs with centre punch at 90 degrees for a drilled hole, eight dabs for a reamed hole.
Happy days before CNC!

surfaceblow
7th February 2009, 20:03
I spent one week injecting saw dust before we got to shut down to look for the leak. Some days we had to inject more than once a day other days none. I remember the Cadet getting soaked when he secured the valves in the wrong order. He made a mess, and got the Second Engineer all wet. Saw Dust Bin Valve is always closed first. When you run out of saw dust oatmeal works just as good.

davetodd
8th February 2009, 14:39
Derek
Read your comments with interest and can see some merit as you say.
I have attached a thumbnail of a sketch to make sure this is what you meant.
Best Regards
Dave

davetodd
8th February 2009, 15:01
Anyone had experience of putting in sawdust to try and seal a tube leak?
I spent a year of my eng. app. at Scotts' in Greenock on the surface table marking off. One job was marking off ALL the holes on a condenser plate,, I will try and recall, four dabs with centre punch at 90 degrees for a drilled hole, eight dabs for a reamed hole.
Happy days before CNC!
An interesting article in the Sunday Telegraph today 8th Feb.2009.
A pull-out supplement Offshore Technology and Development has a section entitled "North Sea fixes in demand" by Sean Hargrave.
The topic is concerning LEAKS and mending pipes several hundred feet under the sea.
Always difficult and costly to reach and repair leak sites so an Aberdeen based company, Brinker, has decided to mimic the body's natural healing process."We use platelets, free floating, discrete particles which are injected into a well, pipeline or umbilical and carried to the leak site with the flow in the line. When they reach the vicinity of the leak, fluid forces them into it thus providing a seal" explained Klaire Evans, business develpoment manager.

Now why didn't we think of that instead of messing about with sawdust or loaves of bread????(Cloud)

Regards
Dave

Derek Roger
8th February 2009, 15:32
Derek
Read your comments with interest and can see some merit as you say.
I have attached a thumbnail of a sketch to make sure this is what you meant.
Best Regards
Dave

Exactly Dave ; I was in the process of making the same sketch for clarity ; you have saved me the job !
I am having difficulty reading the text but it seems to read that a leak in the innner endplate will draw air into the condenser from the void space which is at atmospheric pressure and a leak at the outer end plate will cause the coolant to leak into the void . That is how I envisioned the system to work .
A leak in a tube wall within the condenser will still cause contamination .

Derek

eriskay
9th February 2009, 00:36
Derek :

Think you have evolved a feasible description of how such a design could be configured, and that Dave has amplified it well with his follow-on sketch. All looks possible, but it was certainly not a design my Company provided, despite the Enquirer alluding to this.

I am away now to think about it a bit more and ponder on how such an arrangement would fit into a Condesner Shell, be supported, sealed, and the associated Watertube Box arrangement - still some problem areas there in my mind. But meantime thanks for all contributiomns to date and well done !

Angus

Derek Roger
9th February 2009, 02:56
Angus ;
In my view the condenser shell would be welded to the inner end plate.
There would have to be a heavy bolting arrangement between the inner plate and the outer plate and water box . Spacers would be required ( should not be a problem with thermal expansion over 12 mm when being water cooled ).

Loading of the bolting arrangement would require that the water box mass be supported from top and bottom by spring supports ( For ship use also some lateral support )

Chadburm indicates that this may be for nuclear systems ; may well be right but I am not well versed in that subject .

Additionaly I would consider using expansion bellows on the cooling water connections to make sre there are no other loads on the outher end plate which if exsistant would cause bending loads on the bolting arrangement .

It is nice to be retired and given a new challange !!

Kind regards Derek

WilliamH
9th February 2009, 07:55
No one has yet explained how the tube is sealed at the inner tube-plate, as I see it a leak at the joint tube/tube-plate would necessertate the removal of the outer tube plate for access to repair the leak.

chadburn
9th February 2009, 10:54
Ferrules perhap's hence the gap to take into account the amount of ferrule pertruding from the inner faceplate, although as you say if they pass the outer face plate would have to come off, as the Author has indicated it is all a bit "scetchy" at the moment and he is awaiting further details. Bearing in mind he worked for the Company at the time this condenser was supposed to have been built it seems unusual that he has not come across it unless the Company had a Special project's shop with Restricted access.

Derek Roger
9th February 2009, 15:05
No one has yet explained how the tube is sealed at the inner tube-plate, as I see it a leak at the joint tube/tube-plate would necessertate the removal of the outer tube plate for access to repair the leak.

Could the inner plate tubes be expanded into the endplate similar to boiler tubes ?? Only a pressure differential of 1 bar .
Derek

Derek Roger
9th February 2009, 15:59
I did a bit of Googling on nuclear steam plant condensers and it seems they favor titanium tubes and end plates ( welded connection ) but no mention of double end plates .
I did however find on Yahoo " double end plate steam condensers " and came up with Navy EF ittstandard .com which shows a double tube double end plate model for use on Navy surface vessels and subs .The description refers to a 1/4 inch drain between the tube sheets to detect leakage . The cooler was not a large main condenser but the technology is obviously available .

Keep looking chaps . Derek

davetodd
9th February 2009, 16:30
Well done Derek.
That set me off on the Googlepedia.
try this:-
http://canteach.candu.org/library/20043211.pdf
then go to Fig.4
Regards
Dave

Derek Roger
9th February 2009, 16:51
I am having trouble opening pdf files for some reason ? and I made an error in my last post which I will correct ( it was not google but Yahoo that I used for my search )

Derek

davetodd
9th February 2009, 17:08
I have attached a thumbnail for you.
Dave
p.s. Canteach candu is the non profit making side of Canadian NUCLEAR energy establishment aimed at educating readers in the business the canadians have designed.
Some interesting topics are on their website.
Geordie Chief had a notion about this.
I know I didn't.
Dave

eriskay
9th February 2009, 17:32
Well done, everyone, that now seems to establish that a technology exists, and has been used, to provide a 'double-indemnity' inter-tubeplate gap that ensures any leakage is dispersed safely, thus avoiding contamination of clean water (condensate) system. Thus, the concept is proven as far as I'm concerned, thanks to all your good work and thinking caps.

Have still not figured out the practicalities of how the whole assembly is configured and, as William has pointed out, how the inner positions are accessed for expansion/sealing/remedial work.

Definitely not my Company's work, am prepared to bet 1p on that (Heh, I'm Scottish!) Would not have thought it was nuclear-related either, our parent company (Weir) did a lot of the high-pressure H/E stuff and as far as I recall they were nornally all-welded construction and some exotic materials.

In our own area of specialisation, mainly seawater distillation plant, our tubeplates were Admiralty Brass or zinc-free Ni Al Br, with tubes in a mixture of titanium, Al Br, or Cu NI, depending on what area of the plant they were in and the related operating temperatures. Maximum differential across the tube expansions would be of the order of 7-8 bar g and, providing rolled correctly, it was very rare we experienced tube leaks due to expansions. (Experienced a few due to other reasons, mind, but that's another story as they say.)

Thanks again, everyone, very informative and interesting from you all,

Angus.

Derek Roger
9th February 2009, 22:31
Thanks Angus for raising the question ; It has been fun chasing it down . Regards Derek

chadburn
10th February 2009, 10:55
It has been an interesting debate Angus and has brought back memories of old style Marine Engineering practises, some very old, again thanks, Angus.

eriskay
10th February 2009, 23:03
Unfortunately I am still 'in drydock' at present, mobility next to zilch, but when I'm back to work I will be following this one up with the original enquirer to see what further info I can glean on their specific application. Be assured that if and when I learn more, you good folk will get the details forthwith, if not fifthwith.

Thanks again !

davetodd
10th February 2009, 23:35
eriksay
I'm sure we all hope your health and mobility improve swiftly.
Best Wishes
Dave
P.S. The attached is from a book by John Perry D.Sc, F.R.S. published in 1902
Obviously he had his own ideas regarding condensers.
The lower text reads:-
Brass casing generally cylindrical in shape: 8 to 15 feet long. Tube plates T 1 inch thick.
Usually water inside the tubes and steam outside.
There are two advantages in having the steam inside the tubes: the deposited grease is more easily removed and the room keeps cool. the disadvantage is the graeter weight of water, more joints to leak, more tendency to corrosion.
The tube plates are stayed and the tubes when long have a mid support as shown.
We have every reason to believe that if the condenser tubes were made very much smaller than at present, the whole condenser might be much smaller in size.

Derek Roger
11th February 2009, 00:40
eriksay
I'm sure we all hope your health and mobility improve swiftly.
Best Wishes
Dave
P.S. The attached is from a book by John Perry D.Sc, F.R.S. published in 1902
Obviously he had his own ideas regarding condensers.
The lower text reads:-
Brass casing generally cylindrical in shape: 8 to 15 feet long. Tube plates T 1 inch thick.
Usually water inside the tubes and steam outside.
There are two advantages in having the steam inside the tubes: the deposited grease is more easily removed and the room keeps cool. the disadvantage is the graeter weight of water, more joints to leak, more tendency to corrosion.
The tube plates are stayed and the tubes when long have a mid support as shown.
We have every reason to believe that if the condenser tubes were made very much smaller than at present, the whole condenser might be much smaller in size.

Deposited Grease ???? Good grief ! I suppose that was with triple expansion engines and a lack of a suitable hotwell with filters ( coconut matting as I remember in my old books )

Perhaps the source of another happy discourse ?

Derek
PS Get back up to speed Angus we need you .

chadburn
11th February 2009, 06:54
Eriskay, as other's have wished you, get well soon, as you are in engineering I am presuming it is New Knee/s after a lifetime of kneeling on oily bit's, grating's and chequer plate's.

Dave, It's certainly a type of Condenser I have worked on in the past with a centre tube support plate, it needed 3 people to re-tube it (1 inside the Condenser plus 1 on each end plate), it was re-tubed starting from the bottom and then working up the sides (with the smallest and lightest person inside the Condenser, entry/exit gained through the top flange which was usually Boiler Door size and offset from the centre plate) Lots of shouting (3rd row, 4th from the right etc),on triple expansions all sort's of filter mediums were used in the Hotwell (see forum on Yacht "Cangara") baskets of Coke, Oakum and many other's. It would appear that putting the steam through the tubes was not considered by other Engineer's as a good idea. I am still trying to remember the name the of that paint we use to use on the inside of the Condenser Door's.

davetodd
11th February 2009, 09:06
Chadburn,
might that paint be Apexior?
If I remember it was available in three grades, Apexior 1,2 or 3.
Dave

chadburn
11th February 2009, 10:11
Spot on Dave, for the life of me I could not remember the name of the stuff.

eriskay
14th February 2009, 00:13
Chadburn and DaveTodd :

Ah .... the old Apexior No. 3, a favourite coating for grey cast iron waterboxes, valve chests, doors, manways, etc. Many a time I have referred to it when examining highly expensive surface treatments such as high-tech micaceous iron oxide treatments at 300-400 microns thick that have failed abysmally in a short time allowing the onset of serious corrsion attack. Great in a lab, but not so clever in the field due to demanding surface preparation and primer standards that are often impracticable in complex spaces, hostile climes, etc. Good old Apexior, slap it on and a year later you will invariably find it still intact and doing its job when she goes for her next annual drydock/refit. Still need to prepare before application, but not to SA3 or suchlike high quality. Wonder if it is still manufactured?

No, not the knees, apparently sciatic nerve damage, possibly disc-related, and an unpleasant wee condition it is too. Left leg pretty numb from knee down to ankle, not responsive, and this is Week 4 of it. Back to Dr in a week to see where we go from here. He thinks it will gradually 'fade away', I'm not quite as confident as the time slips past with very little improvement. Och, well, could be worse, could be both legs .... : -)

Regards / Angus

davetodd
14th February 2009, 08:25
Angus
try this:-
http://www.dampney.com/Products/Products.asp?ProductID=30
Dave
P.S. For condensers, not legs!

chadburn
15th February 2009, 11:29
If only they had used it on the old Vauxhall Victor's perhaps they might have lasted a bit longer it was really good stuff. Sorry to read about the back eriskay I compressed my Spine due to a Motorbike crash and spent 3months with a bag of Sand tied to each ankle in the early 1950's, I am now 10ft tall!!