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DOC / DPF / Catalyst Options for Diesel Mains & Gensets

Discussion in 'Technical Discussion' started by Nigel Oakey, Aug 6, 2019.

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  1. Nigel Oakey

    Nigel Oakey New Member

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    I am replacing the dry exhausts on my twin mirrored pair of Gardner 6L3B's on my 1965 G. De Vries Lentsch Jr built TSDMY. As part of this I am exploring the possibility of including a catalyst or some kind of particulate filter (DPF) into the new arrangement which also includes restoration of the funnel and mast back to its original 1965 incarnation (as per the pic). The engines will thus exhaust at a reasonably low air-draft height through a funnel which sits atop the original boat deck (as per the pic). The boat deck these days is used much more for general entertainment and therefore I seek to keep it as free as possible from smoke, particulates and noxious gases. Obviously I understand that back pressures can't be compromised. I'm most interested in whether anyone has done this before and if so, what was your approach? Please no-one try and talk me into a wet exhaust conversion. With regards to the Gensets they are a pair of new Cummins Onan MDKR17.5KVA Quietline Series again being directed dry up the stack and on to the boat deck. So X4 chimneys in all.

    Sirdar Sea Trial.JPG
    Last edited by a moderator: Aug 6, 2019
  2. Nigel Oakey

    Nigel Oakey New Member

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    I guess this is an area that not two many people are keen on venturing discussion on. Having said that, I've just looked at the discussion threads in these forums on both the D'Angelo Seaclean system and the one where a reader was speculating on the application of AdBlue systems which exist in trucks and cars. Both those discussions are now having me err on the side of dispensing altogether with the idea of a DPF / catalyst system. With a long range motoryacht such as mine there likely to be long periods during passage-making where the Gardner engines will be running at 40-60% of full load on low RPM's. Similarly, even though I have deliberately bought 17KVA gensets to "up the average loading" of the gennies (and I can even split the bus between the two gennies), there will be many periods where they sit at 30 - 40% of load. Both of these conditions are ripe for the clogging of DPF's and catalysts it would seem. Interestingly Toyota here in Australia is now facing class action from its fitting of DPF's to all Hilux and Landcruiser Prado SUV's since 2014. Owners have been complaining about loss of engine power and massive loss of fuel economy. There seem to be reports of the same in the commercial trucking market in the US and Europe where many workshops are now offering services for the removal of DPF systems which have been installed on big rig diesel trucks. Seems this area is a veritable can of worms that I'm going to steer clear off. The only option I might still loot at is the option of a flanged "can" filter that can go at the very end of the exhaust pipe. If I keep all the gennies and main engines with minimal elbows on the run through the stack and use only "straight through" absorption type silencers this might be be the way to go as they will be easily removed in a position outside the funnel on the boat deck . The idea being that you could simply unbolt them and clean them out manually.
  3. Nigel Oakey

    Nigel Oakey New Member

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  4. captholli

    captholli Senior Member

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    The Sea Clean is an excellent system with multiple functions besides soot and hydrocarbon reductions through regeneration and particulate filters and a great secondary function is being a dedicated load bank through heating elements for your 30-40 % loaded gens however, my last discussion with Rick Boggs was that they ( Sea Clean) were in the process of working up a system for smaller KW outputs like your 17.5 gens as at that time their systems were for lager KW output prime movers. I don't think that you received much feedback for regeneration due to your smaller KW units as its been discussed a few times in YF threads but most if not all DPF systems are for larger outputs. The Urea DEF might be your only option if going Green is in the cards but Urea obviously wont address your loading solutions.
  5. d_meister

    d_meister Senior Member

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    I've been lurking on this one after scrubbing my initial reaction in case there was some incredible tech out there that I wasn't aware of. It seems to me that the objective of basking in the sun downwind of the original low profile stack with neither soot nor stink is a "wish too far". Sitting in traffic here in California, there is never any doubt that the brand new pickup truck in front of me is a diesel or not. The best and most stringent restrictions don't clean up the aroma. You may be better served looking into a bridle anchor rig that brings the wind a few degrees off the bow. Add a stern anchor?
  6. PacBlue

    PacBlue Senior Member

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    There is a well known Megayacht that injects perfume/scent to the exhaust stack, there was a directive in the build order that no exhaust fumes would be detected while running gensets.
  7. Capt Ralph

    Capt Ralph Senior Member

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    There are times when we cruise with the windows open, then even our small 9kw gen-set is under loaded.
    That is why I went with inverters long ago. Helps the gen-sets live longer & cleaner lives.
  8. motoryachtlover

    motoryachtlover Senior Member

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    I have been watching this thread as well. I hesitated to comment because some will take a layperson’s perspective and slice and dice it to death with science to the point that only scientist and/or engineers can hope to understand the discussion leaving the OP with no answers or directions to go in.

    My opinion is do not add a regen or DEF system. We have several trucks large and small and it is definite drawback and source of breakdowns. At least we can pull of the road at sea you won’t have that option. These systems definitely come with a fuel consumption penalty. I will say that on the trucks with DEF the exhaust pipes are clean and not black so it is doing something. I will also concede that on heavy equipment the systems seem to have gotten better and less problematic. But usually we try to trade in after 2000 hours on the smaller equipment and 4000 on larger equipment. In my opinion the technology is not reliable yet and wouldn’t dare go fooling around with your old school Gardners. Also apparently some bad DEF got distributed in our area with very expensive consequences.
  9. Nigel Oakey

    Nigel Oakey New Member

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    Thanks for all your comments. Please also forgive my spelling / grammar in my reply to my own post above. I was typing on my phone and was not checking! All your comments are very useful. I approached De Angelo through their agent in Australia hoping they had a small Seaclean system. The response was negative at this stage. I agree Capt Ralph that inverters are the way to go and I like to have a quiet ship on the inverter but sometimes with families aboard and everything that comes with that the genset has to come on! The more I have looked the more I have seen the internet is rife with engine repairs and even failures from diesel motor cars with DPF's / DOC's fitted....things seem to go terribly wrong when these diesel vehicles are used for daily short commutes where the engine never gets hot enough or runs long enough to regenerate the soot. In studying this topic I think I've now figured out why my wife's Mercedes GL SUV recently went in for a $6000 service to fix engine oil leaks even though it was only 3.5 years old. I bet there was a clogged DPF to blame as she only does short runs to school and shops etc... Then motoryachtlover has confirmed the same in trucks. The diesel engine community is in a real mess with this stuff!

    For now I'm going to keep both gennies and mains in a straight a run as possible up the stack with straight-through absorption type silencers to minimise back-pressure. I'll then explore a simple "clip-on" style scrubber which someone mentioned in another forum. The clip-on unit is apparently is "the size of a coffee can" and clamps on the end of the exhaust pipe. The purifier is easily removed (and I assume cleaned) when it is no longer needed. https://www.foleyengines.com/products/exhaust-purifiers-scrubbers/diesel-exhaust-scrubbers/ Sounds to good to be true but at least this way I've not got something trapped in the middle of my exhaust between two flanges out in the middle of nowhere!...and in long range passages i can just remove the thing. Seems that back pressure exhaust monitoring is a good idea when playing around with these things. Any idea how to set up a monitoring point in the exhaust arrangement top check back-pressure?
  10. Capt J

    Capt J Senior Member

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    Another option is to make the generator underwater exhaust and only have the bypass air run up the stack. Generally the modern generators run clean if they have at least a 40% load on them.
  11. motoryachtlover

    motoryachtlover Senior Member

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    Nigel I forgot to mention that I like your boat. Does the canoe stern help in a following sea? If you feel like it give us brief summary of the boat.
  12. Capt Ralph

    Capt Ralph Senior Member

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    Then you crank up the gen-sets and when properly loaded, you know the hotest-cleanest exhaust is going up the pipes. Just trying to help when your gen-sets are under loaded.
  13. Nigel Oakey

    Nigel Oakey New Member

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    Trickiest one of all is when it lights out and its too hot and sticky to NOT have the aircon on! Even X4 Cruiseair units go down to quite a low load when they are all working to just maintaining the airtemperature through the night. But I guess that's when you really don't care whats happening up top on the bat deck because no-one's up there then! The trick would then be to load it up with services first think in the morning and clear the exhaust lungs then
  14. Nigel Oakey

    Nigel Oakey New Member

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    Thanks. The canoe stern definitely has a positive impact in a following sea. She is a 1965 “Deep Ocean Class” long range motoryacht built by G. De Vries Lentsch Jr in Amsterdam. The build was commissioned by a New Zealand industrialist who sailed her round the world direct from the yard when the build was done. G. De Vries Lentsch Jr was the “by Royal Appointment Yard” who built the yachts for the Dutch Royal Family. Starting in 1840 it was the oil crisis of the early 1970’s that eventually saw their demise after building nearly 3000 custom craft. I am only the fourth owner of MY Sirdar and I have undertaken a total refit from the keel bar up. I hope to launch within a few months but will take longer if I need to in order to achieve exacting quality on every aspect.

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