propane gensets

[bam55]

At what KW will a diesel genset become more reliable than a proipane fired genset? I've heard over 500KW for power generation but below this its about the same except for thier inherent advantages and disadvantages.

 

[MintJulep]

A diesel engine should always be more reliable than propane engine, simply because there are fewer parts.

 

[ccw]

MintJulep is correct. I have a friend involved in developing new U.S. Army field gensets. They are going to diesel across the board to use the Army Universal Fuel JP8. They looked at the little VW diesel as being very reliable. They are currently using a small, air cooled, 3 cylinder diesel.

 

[taylorg]

ccw - I also imagine it will be easier for them to source back-up diesel fuel in the battlefield country than propane. Diesel also easier to transport and distribute in bulk.

 

[bam55]

Yes I agree with all the above. Is not the propane "fuel/firing system hotter than diesel at higher KW therefore becoming a less reliable engine. However at small engine sizes this doesn't matter so much.

 

[chicopee]

As taylorg said diesel is more widely used throughout the world; and the diesel cycle is more efficiency and durable than open air cycle.

 

[ScottyUK]

Depends to some extent what you mean by 'engine'. A turbine has one major moving part and is very happy to run on propane. Once you are moving into MW-plus sizes the economics start to swing in favour of the turbine if you have a compatible fuel source, particularly if you can use the waste heat. Bunker oil is clearly only fit for a large diesel engine, or a steam-raising boiler.


----------------------------------

Sometimes I only open my mouth to swap feet...

 

[zeusfaber]

There's not a lot to stop you putting diesel through a turbine. Most of the Royal Navy's gas queens run F-76 (look on it as a straight mix of diesel and contaminants) in their Tynes and Ollys.

A.

 

[ScottyUK]

Agreed - light diesel oil is fine as a turbine fuel and easier to handle than gas in a mobile application but 'diesel' engines are a species with a lot of variants: the big multi-MW low speed machines used in medium sized power plants and large merchant vessels burn something nearer to tar than automotive diesel which requires heating before it will even pass through the injectors. Our industrial turbines burn natural gas, propane, or 'naphtha', a rather variable mix of the lighter hydrocarbons.

----------------------------------

Sometimes I only open my mouth to swap feet...

 

[taylorg]

Getting slightly off topic now....but medium and slow speed diesels have evolved in leaps and bounds in the last few years. You can get medium speed engines with outputs over 20MW and slow speeds reaching 75MW per unit. They can run on gas or HFO ('dual fuel') and have an open cycle efficiency of around 46%. Pretty good!