ABB Turbochargers - Sealing Air Passages are important!

A place to exchanges questions and ideas of a technical / procedural nature. Go ahead, try to stomp us !
User avatar
Byron510
Bilge Dweller
Posts: 3
Joined: Tue Jul 27, 2010 9:04 am
Currently located: Vancouver BC

ABB Turbochargers - Sealing Air Passages are important!

Postby Byron510 » Mon Aug 16, 2010 3:55 pm

My first post here, I have seen some interesting threads while lurking, and I thought I could chime in for a little tip here.

I thought I should pass this little note along reminding engineers to do such a simple task during your routine overhauls of your older ABB/BBc VTR series turbochargers.
This past week I did a rotor exchange on an ABB VTR 454 P11 turbocharger (T/C) on a Wartsila 8L38 engine. The T/C had been serviced about a year prior, however in recent months the turbine side (T/S) oil would turn black in a matter of hours. Additionally at full load, sparks from combustion gas could actually be seen emanating from the T/S bearing chamber vent on the gas inlet (G/I) casing. The sight glasses had turned completely black and the crew was literally in the dark as to what was going on. The vessel shall remain anonymous to protect the innocent. :D What I found below was behind the bearing cover. It looks black, and maybe you won't think this is such a big deal, but carbon and oil make a great grinding compound for roller bearings! However, behind that pump is a centrifuge. That centrifuge has three oil jets that are about 0.5-0.75mm on diameter. Two were blocked entirely, the last one was very close to being blocked. With no oil, at 14 000 RPM and a rotor weight of around 100 kg's - well it wouldn't take long for the heat to build and a serious catastrophic bearing failure was imminent. Likely in seconds completely destroying the entire rotor, cover ring and wall insert and possibly if the load on the engines was high enough at the time, total loss of the turbocharger at great expense and downtime.

All of this because the previous service engineer didn't simply check to see if the clearing air passage was ...clear!

Let me explain the clearing air passage and it’s duty to turbocharger life. On all of the roller bearing style ABB T/C's(VTR 0,1 and 4 series) there is a passage that starts just outside the partition wall at the diffuser area, bleeding a small amount of pressurized air though a passage in the gas outlet (G/O) casing, and around a channel into the G/I casing, and then thought to the shaft area between the bearing chamber and the turbine blades. This air pressure will be higher than the exhaust gas pressure, and will tend to keep the exhaust gas pressure from traveling down the shaft into the bearing chamber where it can do as shown below. A simple air seal (downstream of the more complicated labyrinth seals).

So next time you happen to be doing a turbocharger rotor swap, and the rotor is out, take the 10 minutes to get an air line down to the turbocharger, wrap a rag around the end of the hose and give the passage a good blow from the compressor side. You should be able to feel some air flow as you put your hand up in to the seal bush area. A failure to follow this simple step just about cost this vessel a turbocharger.
Just a little heads up to keep it all running smooth on your aging ABB/BBC VTR series turbochargers.

Byron
Attachments
DSC00305 (Small).JPG
The seal bush area; sealing air comes up through this channel and splits when it hits the shaft, roughly half of the sealing air venting with the gas the other half venting out through the bearing casing.
DSC00305 (Small).JPG (44.83 KiB) Viewed 7235 times
DSC00299 (Small).JPG
How the bearing and pump looked - very ugly indeed!
DSC00299 (Small).JPG (54.86 KiB) Viewed 7237 times

User avatar
JK
Enduring Contributor
Posts: 2676
Joined: Tue Sep 04, 2007 2:29 am
Currently located: East Coast, Canada

Re: ABB Turbochargers - Sealing Air Passages are important!

Postby JK » Tue Aug 17, 2010 12:41 am

Welcome to Diesel Duck and thank you for the informative post.

User avatar
Mikkelsborg
Leak Patrol
Posts: 44
Joined: Wed Dec 09, 2009 11:06 am
Currently located: Morristown, New Jersey, USA

Re: ABB Turbochargers - Sealing Air Passages are important!

Postby Mikkelsborg » Tue Aug 17, 2010 2:26 am

Thanks for the input Byron.
-
In addition I can add that on some VTR 201 turbochargers it has been necessary to make an external line from compressor casing in order to secure enough sealing air pressure. Often used on DEUTZ engines...
Mikkel Elsborg
PJ Diesel Group
(http://www.pjdiesel.com)

User avatar
The Dieselduck
Administrator
Posts: 2683
Joined: Sun Jul 22, 2007 1:41 pm
Currently located: Nanaimo, British Columbia, Canada (West Coast of Canada)

Re: ABB Turbochargers - Sealing Air Passages are important!

Postby The Dieselduck » Tue Aug 17, 2010 3:58 am

Excellent post Byron. Thank you, and welcome to The Common Rail.

I have never had the opportunity to take on of these apart myself, but I will certainly keep it in mind.
Martin Leduc
Certified Marine Engineer and Webmaster
Martin's Marine Engineering Page
http://www.dieselduck.net

User avatar
Byron510
Bilge Dweller
Posts: 3
Joined: Tue Jul 27, 2010 9:04 am
Currently located: Vancouver BC

Re: ABB Turbochargers - Sealing Air Passages are important!

Postby Byron510 » Tue Aug 17, 2010 7:05 am

JK wrote:Welcome to Diesel Duck and thank you for the informative post.


The Dieselduck wrote:Excellent post Byron. Thank you, and welcome to The Common Rail.

I have never had the opportunity to take on of these apart myself, but I will certainly keep it in mind.


Thanks for the friendly welcome.

Mikkelsborg wrote:Thanks for the input Byron.
-
In addition I can add that on some VTR 201 turbochargers it has been necessary to make an external line from compressor casing in order to secure enough sealing air pressure. Often used on DEUTZ engines...


Would this simply be an external tube running from the A/O casing over to the cover plate for the sealing air passage on the G/I casing?
If so, I could see how this can be beneficial if needed. The port that runs axially between in the G/I and G/O casing isn’t that large, and if more clearing air is required I could see how this could be beneficial. However I’ve not seen an application where it’s required.
On the Deutz application that you mentioned, do these engines often run at very low load where no real pressure is being generated on the A/O side?

Thanks again for the welcome; I’ll hope to contribute on the larger turbocharger (>500 kw) side of things where I can. Great site.

User avatar
Mikkelsborg
Leak Patrol
Posts: 44
Joined: Wed Dec 09, 2009 11:06 am
Currently located: Morristown, New Jersey, USA

Re: ABB Turbochargers - Sealing Air Passages are important!

Postby Mikkelsborg » Tue Aug 17, 2010 3:42 pm

Hi again Byron, yes - the quick fix is as simple as an external tube as per described :-) Efficient, simple, quick and can be done onboard without external service :-)
Please do not hesitate to contact me if you have turbocharger questions, as we service a lot of different engine applications world wide.
What fuel are you running the W38 on ? Perhaps we can support with som experiences from powerplants in South America, but they run HFO with a very high vanadium content... We have developed a exchange program for their fuelpump plunger and barrels due to extreme wear..
Mikkel Elsborg
PJ Diesel Group
(http://www.pjdiesel.com)

Pengze
Mechanic
Posts: 60
Joined: Tue Sep 23, 2008 8:57 pm

Re: ABB Turbochargers - Sealing Air Passages are important!

Postby Pengze » Mon Sep 26, 2011 3:32 am

Actually talking about the centrifuge holes choked / blocked, while the T/C is in operation with normal operating half / full load, you can observe a thin line of oil rising continuously inside the oil sight glass., this means it is normal. If you see a intermittent or broken line of rising oil then the danger is imminent resulting in T/C failure. Pls see attached video.


Return to “The Workshop”

Who is online

Users browsing this forum: No registered users and 2 guests

 

 

cron