Simple waterwashing of turbineside on two stroke engines

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Mikkelsborg
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Simple waterwashing of turbineside on two stroke engines

Postby Mikkelsborg » Tue Aug 17, 2010 2:31 am

It is possible for the vessels to build simple water washing system onboard for the turbocharger turbine sideby themselves. This came up as clogging in the turbineside became a problem - a side effect from slowsteaming worldwide.

You need one piece 1/2" pipe going down to the center of the exhaust pipe before turbocharger, with a closed end (welded, to ensure no loose parts in system before TC). The pipe have to 20 mm past centerline. In the centerline you then drill a 4 mm hole facing towards the turbocharger.
Then you mount a valve on the end of the pipe on the outside that can resist the heat, where you can connect the water hose.
When connecting the water you should apply it with 3-4 bar pressure and then wash for 10-15 minutes at 10 % load !
Normally we open the drain valve to the turbocharger and wash until we have clear water coming through.

It is important to remove the hose after washing to ensure the system is not filling up with water !

If washing at higher load (than max 10 %), this could cause damage to the turbine blades, as the water particles with hit the turbine blades at high impact causing damage!

You can buy a washing system, but pricing wise the crew can build it cheaper onboard with same results,
Mikkel Elsborg
PJ Diesel Group
(http://www.pjdiesel.com)

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The Dieselduck
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Re: Simple waterwashing of turbineside on two stroke engines

Postby The Dieselduck » Tue Aug 17, 2010 5:29 am

I have carried out water washing of the compressor side of the turbo on many ships, but if I remember correctly we always did it at reduced load, but with a considerable more load than 10%. Wartsila, I am not sure what the official procedure was, but it had been done like that for many years without problems. And the Deutz I worked with also, but mind you it was considerably less water involved. Anyways, this is good advice and real solutions, thanks for bringing it up.

The water side washing I found was pretty straight forward. Your comments brought back memories of the turbine side "washing" though - about using proper heat resistant valves. These were always failing and became quite an annoying operation to do the "walnut wash".

Good times...
Martin Leduc
Certified Marine Engineer and Webmaster
Martin's Marine Engineering Page
http://www.dieselduck.net

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Byron510
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Re: Simple waterwashing of turbineside on two stroke engines

Postby Byron510 » Tue Aug 17, 2010 7:39 am

Individual engine operating manuals will usually specify a turbocharger inlet gas temperature which to not exceed before commencing a water wash cycle. Excessive thermal shock of the components is what you will try to avoid. Usually the engine manufacturer will also state that the engine needs to be stabilized at a specified temperature for 10 to 20 minutes before commencing the water wash cycle. These parameters should be adhered to for best results.

Water washing on both the compressor side (C/S) and turbine side (T/S) of the turbocharger is most effective, but it works in very different ways for either side.

On the C/S, the actual impact of the water droplets (that have mass but no velocity at impact) hitting the compressor wheel is the cleaning action that you are after.

On the T/S, it's thermal shock that tends to break loose the deposits on both the nozzle ring (stationary component) and the turbine blades. It is important the temperature is high enough

Surging…

When water washing, you can expect a surge situation to occur because you are increasing air density (on the C/S) and you are cooling the incoming gas volume (on the T/S). This problem gets compounded on inline engines with multiple turbochargers. If you have a V engine with a single turbocharger per bank, try to do simultaneous cleaning of both turbochargers to prevent surging.

Dry wash...(T/S only!!)

Walnut shells have been used with great effect over the years, especially in heavy fuel applications. The walnut shell method works the same on the T/S as the water washing does on the C/S, using the impact of the media to do the cleaning, yet the media is light enough to blow out the exhaust system up the stack. It’s effective, but like any method it needs to be used constantly in a routine.

A final note to any cleaning method.
If you have not been cleaning the turbocharger on a regular schedule, don't start now! Start cleaning on a regular basis after a turbocharger has been serviced and is clean (and balanced) to begin with. Balance is everything to a turbocharger. Starting a water washing routine after a turbocharger has been in use for 10 000 hours with no cleaning cycle could lead to uneven removal of deposits, leading to imbalance of the rotor which can lead to turbocharger failure in a short period of time. Be cautious when starting a cleaning cycle routine. It’s best to start a routine after a service of the turbocharger is a routine was not in place before hand.


Byron


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