why smoke stacks so fat for diesels of this size?

Discussion in 'Boat Design' started by Squidly-Diddly, Dec 13, 2018.

  1. samir elbaguer
    Joined: Dec 2018
    Posts: 14
    Likes: 1, Points: 3
    Location: Fort lauderdale florida

    samir elbaguer Junior Member

    Not sure about that CG vessel. On modern commercial vessels that stack area, also called fiddley, does contain engine room exhaust and intake fans but most of the space is taken by EGE: exhaust gas economizer.
     
    Angélique likes this.
  2. Angélique
    Joined: Feb 2009
    Posts: 2,455
    Likes: 207, Points: 63, Legacy Rep: 1632
    Location: Belgium ⇄ The Netherlands

    Angélique aka Angel (only by name)

    Thanks for the info Samir,

    Found this e.g. on the 24 MW (32,185 hp) MS Stena Forecaster¹, she was built in 2003 with an EGE on only 2 of her 4 main engines², but they keep adding them, here's a 2016 studyPDF ³ to put also an EGE on one of her auxiliary engines, after earlier an EGE was already retrofitted to the exhaust system of one of the remaining main engines without one, so I guess it indeed can get crowded in the funnels...

    ¹ Wikipedia page in Finnish and in Swedish.

    ² 4 × Sulzer 8ZAL40S diesel

    ³ the below quote comes from page 8, which is page 18 of 43 of the PDF
    [​IMG]
    (large)
     
    Last edited: Dec 16, 2018
  3. samir elbaguer
    Joined: Dec 2018
    Posts: 14
    Likes: 1, Points: 3
    Location: Fort lauderdale florida

    samir elbaguer Junior Member

    You're welcome. I wonder why they kept adding EGSs? I can see two, but four?
     
  4. Angélique
    Joined: Feb 2009
    Posts: 2,455
    Likes: 207, Points: 63, Legacy Rep: 1632
    Location: Belgium ⇄ The Netherlands

    Angélique aka Angel (only by name)

    Looks to be for each engine one EGE, so maybe one more to go, if they can fit them in . . ?
     
  5. samir elbaguer
    Joined: Dec 2018
    Posts: 14
    Likes: 1, Points: 3
    Location: Fort lauderdale florida

    samir elbaguer Junior Member

    EGE is basically a water boiler mounted on the exhaust pipe. Hot gases coming from an engine pass around the water tubes in the EGE and produce steam. Steam produced this way is used on diesel ships as virtually a free power source to heat heavy fuel, to reduce its viscosity so it can flow, inside tanks and piping to-from engines, purifiers, keep the engine warm in port, hot water for the accommodation etc; Most of my sea time was spent on single engine ships with a single EGE accordingly and the multi engine boats I worked on were too small to have one. My guessing is that this ship had two when it was built is because the available horsepower was split between multiple engines and each individual stack couldn't produce the power required to provide necessary steam. But four of them seems like an overkill. I wonder why they kept adding them. You kind of piqued my curiosity.)
     
  6. samir elbaguer
    Joined: Dec 2018
    Posts: 14
    Likes: 1, Points: 3
    Location: Fort lauderdale florida

    samir elbaguer Junior Member

    I think I found the answer! I think the way this ship was designed is to use two engines, the ones with the EGEs as primary engines to be run every time the ship was underway. The other two were auxiliary, to be used while cruising or full speed. By adding EGEs on more engines it gave them more flexibility as to which engines to use while doing maintenance on others.
     
  7. Angélique
    Joined: Feb 2009
    Posts: 2,455
    Likes: 207, Points: 63, Legacy Rep: 1632
    Location: Belgium ⇄ The Netherlands

    Angélique aka Angel (only by name)

    (added note: at first I've missed and 2 × cross posted the last above post while I was thinking it over, and doing other things)
    Well, that's what I wondered too, what's the application of all the extra saved heat . . ?
     
    Last edited: Dec 16, 2018
  8. Angélique
    Joined: Feb 2009
    Posts: 2,455
    Likes: 207, Points: 63, Legacy Rep: 1632
    Location: Belgium ⇄ The Netherlands

    Angélique aka Angel (only by name)

    On second thought, I guess they still can save on the fuel for the boilers, or maybe they have started to sail faster and need more heat to heat up more fuel faster, the below is from the quote in post #17 . . .

    ‘‘ . . . . The oil-fired boilers have a maximum steam output of 2800 kg/h each without economizers and a maximum steam output of 3300 kg/h each together with economizers, . . . . ’’
     
  9. samir elbaguer
    Joined: Dec 2018
    Posts: 14
    Likes: 1, Points: 3
    Location: Fort lauderdale florida

    samir elbaguer Junior Member

    Oil fired boilers, we call them auxiliary boilers, are only used in port when the mains are stopped, or at very slow speed, when exhaust heat is negligible, at least in my experience. All EGEs have an automatic switch that fires oil fired boilers when exhaust heat drops below a certain temp. Why waste fuel when EGE is doing the same for free. With the main engine running exhaust heat is going to be wasted if not used for producing steam.
     
  10. samir elbaguer
    Joined: Dec 2018
    Posts: 14
    Likes: 1, Points: 3
    Location: Fort lauderdale florida

    samir elbaguer Junior Member

    Yes I red this and it confused me. I've never seen EGE and oil fired boiler run simultaneously,
     
  11. Angélique
    Joined: Feb 2009
    Posts: 2,455
    Likes: 207, Points: 63, Legacy Rep: 1632
    Location: Belgium ⇄ The Netherlands

    Angélique aka Angel (only by name)

    From the text and pictures in the PDF it looks to me like they feed the oil-fired boilers also with the heat from the EGE's, so I think they don't have auxiliary boilers, or it's the auxiliary boilers they now feed with the otherwise wasted exhaust heat energy from the auxiliary engines that run the generators 24/7 also when in port...

    Exhaust gas economizer on auxiliary engines.jpg
     
    Last edited: Dec 17, 2018
  12. samir elbaguer
    Joined: Dec 2018
    Posts: 14
    Likes: 1, Points: 3
    Location: Fort lauderdale florida

    samir elbaguer Junior Member

    You got me here. I forgot about this set up.) You don't see this kind of installation very often. What they have here is they are using two economizers, one on the main and one on the ships generators. Because generators run 24/7 but their exhaust is not enough they use their exhaust to supplement oil powered boiler when main engine is secured. There are a lot of different variations on the same idea. The most common set up is something like this. On this one they have steam powered turbo generators thats why you see two oil fired boilers to provide enough steam with engine secured
     

    Attached Files:

  13. Angélique
    Joined: Feb 2009
    Posts: 2,455
    Likes: 207, Points: 63, Legacy Rep: 1632
    Location: Belgium ⇄ The Netherlands

    Angélique aka Angel (only by name)

    Thanks Samir, found here the explanation of the numbers and letters in the drawing...

    [​IMG]
     
    Last edited: Dec 17, 2018
  14. samir elbaguer
    Joined: Dec 2018
    Posts: 14
    Likes: 1, Points: 3
    Location: Fort lauderdale florida

    samir elbaguer Junior Member

    You got it. If you have any questions let me know. I'm not a boiler expert but in my job as a marine electrician worked around them enough to have a basic idea how they work.
     

  15. Angélique
    Joined: Feb 2009
    Posts: 2,455
    Likes: 207, Points: 63, Legacy Rep: 1632
    Location: Belgium ⇄ The Netherlands

    Angélique aka Angel (only by name)

    [​IMG]

    . . . . there's more here...
     
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.