Question about turbos for ChEng

[Clarea]

Saw this link posted in another thread:

 

http://www.seatrade-cruise.com/news/news-headlines/man-primeserv-clinches-large-retrofit-contract-from-royal-caribbean-cruise-line.html

 

I'm curious about the purpose of retrofitting the engines with turbos. Is it simply for more power? Does it have anything to do with adding scrubbers to the ships?

[Scotty G]

Saw this link posted in another thread:

 

http://www.seatrade-cruise.com/news/news-headlines/man-primeserv-clinches-large-retrofit-contract-from-royal-caribbean-cruise-line.html

 

I'm curious about the purpose of retrofitting the engines with turbos. Is it simply for more power? Does it have anything to do with adding scrubbers to the ships?

Turbocharged engines provide more torque at lower RPM. This usually results in said torque being available at much lower RPM than a comparable non-turbo engine.

 

I assume reduced wear and tear would be the main advantage on a fixed plant engine since it will run fewer revs over time.

Edited December 2, 2015 by Scotty G

[Kamloops50]

On cruise ships , torque isn't an issue . The engines run a steady speed and produce electricity for the propulsion and housekeeping systems . It might be away to meet the emission standards with the use of low sulfur fuel.

[FLACRUISER99]

Saw this link posted in another thread:

 

http://www.seatrade-cruise.com/news/news-headlines/man-primeserv-clinches-large-retrofit-contract-from-royal-caribbean-cruise-line.html

 

I'm curious about the purpose of retrofitting the engines with turbos. Is it simply for more power? Does it have anything to do with adding scrubbers to the ships?

I believe they are upgrading the existing turbos not adding.

[Clarea]

I believe they are upgrading the existing turbos not adding.

Makes sense, though I could not tell that from the article.

[chengkp75]

I believe they are upgrading the existing turbos not adding.

 

Yup. Nearly every diesel engine requires a turbocharger to get enough air into the cylinders to support compression ignition. Remember the old Mercedes Benz diesel cars in the 50's to 70's? They were so slow they couldn't get out of their own way, and this was due to lack of turbocharging.

 

They are upgrading from the older radial flow turbochargers to newer, more efficient axial flow turbochargers. Fuel savings and reduced emissions, from the same engine. Much cheaper to replace $60k turbo than a $1.2m engine.

[Clarea]

Yup. Nearly every diesel engine requires a turbocharger to get enough air into the cylinders to support compression ignition. Remember the old Mercedes Benz diesel cars in the 50's to 70's? They were so slow they couldn't get out of their own way, and this was due to lack of turbocharging.

 

They are upgrading from the older radial flow turbochargers to newer, more efficient axial flow turbochargers. Fuel savings and reduced emissions, from the same engine. Much cheaper to replace $60k turbo than a $1.2m engine.

Thanks Chief.:)

[AWOL]

Yup. Nearly every diesel engine requires a turbocharger to get enough air into the cylinders to support compression ignition. Remember the old Mercedes Benz diesel cars in the 50's to 70's? They were so slow they couldn't get out of their own way, and this was due to lack of turbocharging.

 

They are upgrading from the older radial flow turbochargers to newer, more efficient axial flow turbochargers. Fuel savings and reduced emissions, from the same engine. Much cheaper to replace $60k turbo than a $1.2m engine.

 

Yep what your saying. The article did say that they were upgrading plus I don't ever remember an industrial Diesel engine without a turbo or a supercharger.

[chengkp75]

Turbocharged engines provide more torque at lower RPM. This usually results in said torque being available at much lower RPM than a comparable non-turbo engine.

 

I assume reduced wear and tear would be the main advantage on a fixed plant engine since it will run fewer revs over time.

 

As Kamloops says below, the generators run at a constant speed (most are 800rpm) to produce a steady 60Hz power wave. The engines are torn down for complete overhaul every 12000 hours (about every 500-700 days).

 

On cruise ships , torque isn't an issue . The engines run a steady speed and produce electricity for the propulsion and housekeeping systems . It might be away to meet the emission standards with the use of low sulfur fuel.

 

Actually, its a way to meet emissions with less particulate matter. Sulfur emissions are really affected very little by the efficiency of combustion of the engine. Whatever sulfur is in the fuel, comes out as sulfur dioxide up the stack.

 

What it comes down to is; if the turbo can cram more air into the cylinders, you can jam more fuel in and get more power out per revolution of the engine, therefore overall burning less fuel for the same power.

[MisterFidgetpants]

Chief is the turbo used to get enough air for compression ignition or just to harvest exhaust "waste"? I remember old Detroit Diesels that had a direct drive supercharger operating as a scavenge pump just to run and turbos with after coolers for power.

[alfaeric]

Chief is the turbo used to get enough air for compression ignition or just to harvest exhaust "waste"? I remember old Detroit Diesels that had a direct drive supercharger operating as a scavenge pump just to run and turbos with after coolers for power.

 

Both. Going to MAN's web page, they are offering very large exhaust driven turbochargers, specifically for marine two stroke diesels.

 

Although, seems safe to say that the ship's engines have enough power- so this is all about gaining efficiency first, and lowering emissions second.

 

The article specifically states the Enchantment and Grandeur...

 

Those engines are pretty amazing.

 

BTW- chengkp75- I did find out specifically why catalysts are not used. It's all about sulphur.

[chengkp75]

Chief is the turbo used to get enough air for compression ignition or just to harvest exhaust "waste"? I remember old Detroit Diesels that had a direct drive supercharger operating as a scavenge pump just to run and turbos with after coolers for power.

 

Both superchargers and turbochargers are to cram more combustion air into the engine. Superchargers use mechanical energy (typically a belt drive from the crankshaft) from the engine to drive the compressor. This reduces the amount of power the engine can deliver to the drivetrain or generator (some of the output drives the compressor). Turbochargers are far more efficient, in that they use the waste heat of the exhaust gas to drive the compressor. Since without this turbocharger, the heat would go out the exhaust anyway, this "free" energy allows the engine to provide full power to the drivetrain or generator.

 

The exhaust gas spins a turbine wheel and then exhausts, and on the same shaft as this turbine wheel is a compressor wheel that compresses the incoming air for the engine's combustion.

[chengkp75]

Both. Going to MAN's web page, they are offering very large exhaust driven turbochargers, specifically for marine two stroke diesels.

 

Although, seems safe to say that the ship's engines have enough power- so this is all about gaining efficiency first, and lowering emissions second.

 

The article specifically states the Enchantment and Grandeur...

 

Those engines are pretty amazing.

 

BTW- chengkp75- I did find out specifically why catalysts are not used. It's all about sulphur.

 

Almost every diesel engine these days uses turbochargers, superchargers were out of favor when the jet industry's metallurgy allowed for compact gas turbines to be built.

 

Without a turbocharger, a diesel almost will not run. The largest diesels in the world, the MAN 12 cylinder M90ME engine (100,000 hp) won't even start without a couple of electric fans driving air into the engine, and these fans run until the turbocharger spools up enough to supply enough air for proper combustion.

 

Catalysts?

[chengkp75]

And the medium speed engines used on cruise ships don't have the "auxiliary blowers" (electric fans) that the slow speed giants do, but that is why there is a cloud of black smoke when the start one up. Without the turbo boosting the air, combustion is incomplete, and the unburned fuel goes up the stack as soot. Once the turbo gets some energy from the exhaust gas, it gets enough air compressed to completely burn the minimal amount of fuel injected when starting at no load.

[alfaeric]

 

Catalysts?

 

Yea, we discussed some of the cleaning technology a while back- as I had found that similar output engines were capable of using large catalysts instead of scrubbers.

 

Catalysts similar to what cars and heavy trucks use to treat the exhaust.

 

The stationary engines I was referring to don't use bunker fuel- which is pretty heavy in sulfur. Which poisons catalysts. And while that's easily recoverable, the amounts in bunker fuel would mean the engines would be recovering that all the time.

 

So scrubbers are used.

 

Something I should have figured out- as I know how sulfur effects automotive catalysts.

[chengkp75]

Yea, we discussed some of the cleaning technology a while back- as I had found that similar output engines were capable of using large catalysts instead of scrubbers.

 

Catalysts similar to what cars and heavy trucks use to treat the exhaust.

 

The stationary engines I was referring to don't use bunker fuel- which is pretty heavy in sulfur. Which poisons catalysts. And while that's easily recoverable, the amounts in bunker fuel would mean the engines would be recovering that all the time.

 

So scrubbers are used.

 

Something I should have figured out- as I know how sulfur effects automotive catalysts.

 

I thought that might be it, but didn't remember. It's also a case of being able to discharge scrubber water directly into the ocean, when outside 20 miles or so, so that you really don't even need chemicals or retention or treatment systems (though those are needed in port).

[alfaeric]

I thought that might be it, but didn't remember. It's also a case of being able to discharge scrubber water directly into the ocean, when outside 20 miles or so, so that you really don't even need chemicals or retention or treatment systems (though those are needed in port).

 

For the standard that is being asked of them, without the sulfur, a passive (no urea injection) system would work just fine.

 

Alas, the goal was to run the bunker fuel instead of the diesel. Which changes the constraints considerably.

[ORD1166]

Saw this link posted in another thread:

 

http://www.seatrade-cruise.com/news/news-headlines/man-primeserv-clinches-large-retrofit-contract-from-royal-caribbean-cruise-line.html

 

I'm curious about the purpose of retrofitting the engines with turbos. Is it simply for more power? Does it have anything to do with adding scrubbers to the ships?

 

Bob,

 

 

They are going to change out the turbos that are installed. They will being installing a newer ones and updating the system. They do this all time with airplanes, when they are in for overall.

 

Vic

[Clarea]

Bob,

 

 

They are going to change out the turbos that are installed. They will being installing a newer ones and updating the system. They do this all time with airplanes, when they are in for overall.

 

Vic

Thanks Vic, I appreciate the info.:)

[TBone2K]

Cool tech discussion. I know the captain on the Oasis mentioned primary 12 cylinder and secondary 6 cylinder engines. However I thought on older cruise ships I have heard mention of turbine engines?

[Kamloops50]

Cool tech discussion. I know the captain on the Oasis mentioned primary 12 cylinder and secondary 6 cylinder engines. However I thought on older cruise ships I have heard mention of turbine engines?

 

There are some ships built the use modified jet (turbine) engines to generate the electricity . These usually say " GTS ship's name " or "OTS ship's name".

As far I can remember only RCI had ships that use turbines as main engines.

Most use diesel and the turbine is used as quick source for electricity.

QE2 was turbine when built . They later replaced them with diesels. Operating cost was to high and unreliable as well.

[chengkp75]

Oasis has 3 16 cylinder engines, and 3 12 cylinder engines. Most ships will have a mixture of two different sized engines to allow for better optimization of the plant under varying load conditions.

 

Some ships, mainly RCI and Celebrity, if memory serves, and now the newer Cunard liners, use some gas turbines to generate electricity. The idea was to use the gas turbines in areas where emissions were strictly controlled, like Alaska, but it was soon apparent that the gas turbines were very inefficient at less than full load, so nearly all of these ships have installed at least one diesel generator to operate the hotel load in port.

 

The Radiance class at RCI was somewhat unique in that they utilized the exhaust gas energy from the gas turbines (think of a plane's exhaust) in waste heat boilers that generated steam for steam turbines to generate more electricity.

 

The Cunard gas turbines are massive, each about 150% of the power of the diesels onboard (the same as the larger Oasis diesels), so they are only used when going in the 22-30 knot range.

 

The QEII was steam turbines, and the world started getting away from steam propulsion (the US was the last major holdout, most of the world had gone to diesels after WWII) at the time of the 1973 oil crisis, since diesels are far more efficient than steam propulsion.

[Biker19]

Some ships, mainly RCI and Celebrity, if memory serves, and now the newer Cunard liners, use some gas turbines to generate electricity. The idea was to use the gas turbines in areas where emissions were strictly controlled, like Alaska, but it was soon apparent that the gas turbines were very inefficient at less than full load, so nearly all of these ships have installed at least one diesel generator to operate the hotel load in port.

 

Celebrity's Millenium class ships have turbine engines and if you ever use deck 1 to embark/disembark you'll see a whole spare engine as you walk in/out.