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Mardi Gras engines started for the first time


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Did I read cruises on it are pushed back to February now? About a 4 month delay.

 

Cruising buddies are looking at Sept. 2021 . Don't think DW will be ready to sail yet. 

Edited by beerman2
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27 minutes ago, jimbo5544 said:

If memory serves me, engines can run on both.   

 

They could be dual fuel, I dunno. I would think during a break in period all kinds of things could be burning off. Where's that chief?

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1 minute ago, BlerkOne said:

 

They could be dual fuel, I dunno. I would think during a break in period all kinds of things could be burning off. Where's that chief?


 

if it is dual fueled that could be fuel oil burning off. If it is strictly LNG fueled there should be no smoke at all, even during break in.

 

 

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10 minutes ago, BlerkOne said:

 

They could be dual fuel, I dunno. I would think during a break in period all kinds of things could be burning off. Where's that chief?

Agree on all counts, he would sef know

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4 hours ago, dan4182 said:


 

if it is dual fueled that could be fuel oil burning off. If it is strictly LNG fueled there should be no smoke at all, even during break in.

 

 

I do know LNG engines smoke, but how much and how visible it is, is another question.

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36 minutes ago, BlerkOne said:

I do know LNG engines smoke, but how much and how visible it is, is another question.


I worked for Lone Star Gas back in 1966-70 back in East Texas. All of our vehicles were dual gasoline/LNG except for the biggest trucks and dozers which were diesel powered.

 

When the light duty vehicles were running on LNG (free to the company) they emitted no smoke of any kind, even on cold start up.

 

Today’s LNG engines should do even better.

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Just now, dan4182 said:


I worked for Lone Star Gas back in 1966-70 back in East Texas. All of our vehicles were dual gasoline/LNG except for the biggest trucks and dozers which were diesel powered.

 

When the light duty vehicles were running on LNG (free to the company) they emitted no smoke of any kind, even on cold start up.

 

Today’s LNG engines should do even better.

 

I'm pretty sure the Mardi Gras engines are larger than what you might find in a light duty vehicle.

 

"In general, the LNG-powered engines produce much less particulate smoke than do diesel engines."

https://afdc.energy.gov/files/pdfs/truk4-3.pdf

 

That tells me they do, if fact, smoke.

 

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Regarding the smoke from the Mardi Gras.  With new engines, the piston rings have not seated into the cylinder liners fully yet, so there will be some burning of lubricating oil, which can cause smoke (just like an old car with worn out rings).

 

The light vehicles mentioned by dan4182 were likely "bi-fuel" and not "dual fuel" engines, meaning they ran on either gasoline or LNG, but not both at once.  Also, these engines require a spark ignition, for both fuels.  Marine engines are true "dual fuel" engines, that can run on any mixture of liquid fuel (from diesel to heavy fuel) and LNG from 100% liquid to 95% LNG.  Note that these engines cannot run on straight LNG, since LNG has too high an auto-ignition temperature, and requires spark ignition which marine diesels don't have.  The 5% liquid fuel provides a fuel with sufficiently low auto-ignition temperature that the compression in the cylinder starts it to burn, and that raises the temperature to where the LNG will start to burn.  So, the smoke may be that they are using heavy fuel as their liquid fuel.  Like trucks, marine diesels are turbocharged, and like trucks, when you start the engine, or increase power rapidly, the turbocharger lags behind the engine's demand for combustion air, and you get incomplete combustion and smoking (dump truck starting from a stop light).

 

There could also be some residual preservatives in the engine or turbocharger from shipment that is burning off.

 

And, if that is the actual moment when the engines were started, that is considerably less smoke than when starting on either diesel or heavy fuel.  Dual fuel engines will smoke, regardless of load, but especially when the engine is not up to operating temperature.

 

And, incomplete combustion in an LNG fueled engine results in "methane slip" or the release of raw methane from the exhaust, and methane is shown to have 25 times the greenhouse gas effect as CO2.

 

And, finally, those might not be the engine exhausts, but the boilers.

Edited by chengkp75
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7 minutes ago, BlerkOne said:

 

or a test run of the incinerators.

Actually, the incinerators, with their primary and secondary combustion chambers, do a pretty good job of complete combustion.

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8 hours ago, chengkp75 said:

Regarding the smoke from the Mardi Gras.  With new engines, the piston rings have not seated into the cylinder liners fully yet, so there will be some burning of lubricating oil, which can cause smoke (just like an old car with worn out rings).

 

 

 

 

I have a question. Your experience and contributions to the forum are much appreciated. I don't know who made the Mardi Gras engines but a nanoslide process is being used in many piston engine cylinders so that the rings do not need to machine in place the peaks of the hash marks. The rings are fully seated at first run, and the precision of the surface finish reduces fuel consumption by about 3% and lowers emissions. Do you know if this process is used on very large marine engines? 

 

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25 minutes ago, Moviela said:

I have a question. Your experience and contributions to the forum are much appreciated. I don't know who made the Mardi Gras engines but a nanoslide process is being used in many piston engine cylinders so that the rings do not need to machine in place the peaks of the hash marks. The rings are fully seated at first run, and the precision of the surface finish reduces fuel consumption by about 3% and lowers emissions. Do you know if this process is used on very large marine engines? 

 

I had not heard of the Nanoslide process, but researching it, it is solely for aluminum cylinder blocks, to replace the traditional cylinder sleeves of steel/cast iron that were needed to keep the aluminum from wearing in the cylinder.  Since marine diesel engines do not use aluminum blocks or cylinder liners, the technology would not apply.  Also, unlike automotive engines, the cylinder block is too large to replace when the cylinders wear out, so individual cylinder liners are used (this also helps in the design of the cylinder cooling passages, since the entire outer surface of the liner is in contact with cooling water, there being rubber rings at top and bottom to seal).  Also, wear rates on these engines are such that they need to be overhauled every 12,000 hours (about every 2 years in normal operation on a cruise ship), with new piston rings, and either re-honed cylinders or replaced ones.

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Regarding the smoke from the Mardi Gras.  With new engines, the piston rings have not seated into the cylinder liners fully yet, so there will be some burning of lubricating oil, which can cause smoke (just like an old car with worn out rings).
 
The light vehicles mentioned by dan4182 were likely "bi-fuel" and not "dual fuel" engines, meaning they ran on either gasoline or LNG, but not both at once.  Also, these engines require a spark ignition, for both fuels.  Marine engines are true "dual fuel" engines, that can run on any mixture of liquid fuel (from diesel to heavy fuel) and LNG from 100% liquid to 95% LNG.  Note that these engines cannot run on straight LNG, since LNG has too high an auto-ignition temperature, and requires spark ignition which marine diesels don't have.  The 5% liquid fuel provides a fuel with sufficiently low auto-ignition temperature that the compression in the cylinder starts it to burn, and that raises the temperature to where the LNG will start to burn.  So, the smoke may be that they are using heavy fuel as their liquid fuel.  Like trucks, marine diesels are turbocharged, and like trucks, when you start the engine, or increase power rapidly, the turbocharger lags behind the engine's demand for combustion air, and you get incomplete combustion and smoking (dump truck starting from a stop light).
 
There could also be some residual preservatives in the engine or turbocharger from shipment that is burning off.
 
And, if that is the actual moment when the engines were started, that is considerably less smoke than when starting on either diesel or heavy fuel.  Dual fuel engines will smoke, regardless of load, but especially when the engine is not up to operating temperature.
 
And, incomplete combustion in an LNG fueled engine results in "methane slip" or the release of raw methane from the exhaust, and methane is shown to have 25 times the greenhouse gas effect as CO2.
 
And, finally, those might not be the engine exhausts, but the boilers.


You are correct in mentioning the the light duty vehicles we ran were on either gasoline or LNG, but not both at the same time.

There was a switch that could be flipped to use one or the other. The LNG was the fuel of choice but it got less mpg when compared to an equivalent amount of gasoline.


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