Carbon Seal in 35ltr Engine Turbocharger

[gasresearch]

Calling all turbocharger guru's.

I am converting a 35ltr Jinan Diesel(China)engine to operating on Natural Gas. The dilema I have is the size of the turbocharger and converting it to operate in a draw thru fumigation fuel system.

My company has acheived this to date on a number of smaller engines upto 27ltr's in capacity, but this one has a turbocharger with an 18mm shaft. The turbocharger guys that I use can only go upto shaft sizes of 16.5mm. Any bigger and there is not a Carbon Seal which they can source.

And this is what I am chasing.

Does anyone know of carbon seals upto and above 18mm's. The brands that we have been using has been Holset.

Part numbers, brands, anything would be most appriecated.

 

[ivymike]

I don't have the turbo info you need, but you've got me curious about your engine conversions. What drives people to pay for a conversion of a diesel to a gas engine, versus buying a new gas engine? Are the converted engines particularly inexpensive?

 

[bcs5274]

try getting a hold of someone with elliot turbocharger, they build turbochargers for large displacement gas engines, might be able to help, the distributor for them that i deal with is sinor engine out of deer park,tx.

 

[gasresearch]

Thanks guys. I have sent an email to Sinor Engines, and will give them a call also to see what they can do.

For the conversion, my company is based in Melbourne, Australia. This engine is fitted to a 400kw generator set. The customer had quotes of AUD$200,000+ to have mains power connected to his site. So he opted for the AUD$100,000 option of having a generator installed.

They were already running a 400kw diesel powered unit, but wanted to reduce their operating costs.

A comparable gas fuelled genset of this size from one of the larger OEM's was over AUD$200,000.

Cheers.

 

[patprimmer]

Is it feasible to use two smaller turbos.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

http://eng-tips.com/market.cfm

for site rules

 

[tbuelna]

gasresearch,

I agree that your turbo compressor-end shaft needs a mechanical seal in order to prevent combustible mixtures from migrating into the turbo center housing, with a pre-mixed intake charge at the compressor face.

Precision carbon face seals are commonly produced in diameters exceeding 100mm. They are used as oil seals on turbine engines. However, it would not be easy to retrofit a carbon face seal into a turbocharger that was not designed for it, due to the axial space required.

Carbon face seals can operate at sliding velocities up to 20 Kft/min, which would equate to about 107,000 rpm with an 18mm diameter. Since they are usually spring-loaded, friction losses and heating can be a concern, so an oil cooling jet may also be required.

http://www.aerospace.rexnord.com/Products/Cartriseal Mechanical Seals/Type1.asp

Also, the axial spring force on the carbon element may vary over its life as the carbon ring wears away, adversely affecting its sealing ability. In order to counter this, some carbon face seals use a magnet ring instead of a spring.

Friction may also be an issue. So some carbon face seal designs use carbon ring shapes that generate hydrodynamic lift to reduce friction.

Hope that helps.
Terry

 

[naturalextraction]

Perhaps I'm missing something in your question, but here's some thoughts. I've run Lighter element gasses in my draw through system as well as liquid fuels. Over 35K miles later I've never experienced any problem with my set up. First off we mated a Holset with a Schwitzer to meet my desired specs for this application. We machined a new backing plate but kept with the steel ring design. Although we've machined our own carbon seals for mostly the Pro Charger system we used to run on other vehicles.(They work better on smaller turbo's and or on larger compressors not spinning faster than 100KRPM. Not without further modifications anyway).
With out getting into gobs of detail here, typical conventional thinking does not fare well here. Utilize the turbos compression capabilities while keeping a non traditional stoichiometric charge (for these lighter gasses) going into the compressor housing. (Thus the mating of two different company turbo components) Also inlet temperatures and compressor temperature output is needed to be part of the equation along with timing considerations etc. I DO utilize a BF valve on the output side of the compressor housing with an opening ratio slower than your metering devices BF valve. This primarily to keep from oil being sucked out of the center housing. Again I've never had a problem. Your metering devices BF valve needs to be able to reroute back charge from deceleration. If it's a steady RPM engine, not to worry. Keeping waste heat in check or utilized it more constructively is also key to utilizing lighter element gasses in a draw through method. (keep in mind all your gas laws/Theorems related) There are upsides and downsides but with the appropriate configuration and controls they seem to work best in a "draw through" means. In our application anyway.