Diesel Standby Generator - Life Expectancy 1

[nhcf]

Can anyone point to a good reference to evaluate life expectancy of diesel engine-driven generator in an industrial, standby application?

We have a 750 kW unit. I have seen some reference suggesting 10000 - 20000 hours, depending on quality of maintenance, frequency of operation, loading, design etc.

This particular unit is a standby, thus does not run many hours per year - assuming regular maintenance are these hour estimates reasonable? At less than 100 hrs per year, is it reasonable to expect 50 yrs out of the unit?

Thanks for any references/insight.

 

[catserveng]

A lot of numbers get thrown around, in determining "life expectancy", you may need to be more clear on what you actually mean. A lot of standby packages can last up to 20 years as long as properly maintained, after that time, while the prime mover (engine) can still continue to provide the expected power and response, auxiliary equipment, especially cooling systems, will likely require some form of either major maintenance or replacement. Also, depending on environmental conditions, such as high humidity, coastal conditions, extreme weather, things like radiators and exhaust systems may suffer and require earlier attention.

Also, the impacts of air quality regulations will have an increasing impact on determining how long a unit can remain in service. You don't state where you are considering locating the unit, but in areas with strict environmental regulations, units may require replacement if the have a large amount of repair work to be done, or no longer meet an exhaust emission criteria. Also site factors can force replacement of a unit, such as an expansion requiring additional capacity, and to secure permitting the existing unit must also be replaced.

How you operate and test the standby unit will also have a huge impact on its actual service life, excessive run times at low loads will cause poor combustion, reduced response, internal deposits and slobber. Most standby units are required to start, quickly ramp to rated speed and assume load within sort times, typically 10 seconds or less. Environmental conditions play into this as well, units that require weekly test runs and spend a lot of their time at low ambient temperatures typically show an increased number of failures due to slow supply of lube oil to critical areas, like the crank bearings and turbo's. So additional equipment like lube oil heaters may get added, but these require higher operating cost and regular maintenance as well.

Maintenance for standby units gets deferred quite often, units typically get used much less than a 100 hrs/year, so owners questions need for annual oil and filter changes, regular replacement of belts and hoses, and how often starting batteries actually get changed. It also quite common when looking at a failed unit to find it never had an initial valve adjustment, or other recommended early life checks that are suggested, especially on newer high speed high output lower emission engines.

Generator ends are often neglected, am seeing more and more units with the stator space heaters either turned off or not installed at all. And they are rarely properly tested on a regular basis, so pretty much as long as it starts, makes rated voltage and frequency, and will carry a small portion of its rated load, its called "good". Like engines, generators rated at a certain size used to be much larger and heavier, and way more robust, especially on standby rated units. Todays gen ends tend to be smaller, lighter, with less robust insulation packages and smaller bearings, unfortunately they are mostly neglected until a failure occurs.

So for your question as stated, best answer is "it depends", maybe providing more specific info, such as type of unit, where you are located, environmental conditions, how packaged, how well supported by local dealer/distributor and installation specifics, a better answer can be had.

Hope that helps, MikeL.

 

[ViCH]

If You mean 50 years with replacing all spares and maintenance as per run-hours only - then NO. You will get big troubles already after 2-3 years of operation. Its many spares and maintenance services that You have to do either by run-hours or by standby time if its standby unit. You should follow OEM maintenance manual, where You can find all required info.
For simple example - primary fuel filters on GE V16 diesel engine have to be replaced every 1000 run hours OR annualy, doesnt matter if it have low runtime, good dP, etc..
Of cource, if You are doing all maintenance as per required, You can pretend for long lifetime, but still it will requre modification from time to time, due to some spares End-Of-Life on factories.

Viktor
Electrical Technician II

 

[waross]

Our little plant used two 750 KW sets and three 350 KW sets.
They typically ran 15,000 hours between top end overhauls and 30,000 hours between major overhauls.
Cooling and exhaust were separate issues.
Sets were added or taken down as the load varied, the plant operator rated his loading by the number of cylinders working.
He took pride in always using the minimum number of cylinders to carry the load.

These were old sets. A newer, 1500 KW set was purchased.
The newer set was more fuel efficient to the point that the fuel saving was enough to make the payments on the loan.

Standby sets, on the other hand, tend to age out from years in service rather than hours of use, as was pointed out by Catserveng.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[itsmoked]

Don't forget...



Mice.

A couple mice can bring it all down.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[waross]

A fiend of mine was the head of maintenance at a small private school.
They had an old Detroit Diesel standby set.
About 50 KVA.
It probably dated from the second war or shortly after.
It quit running.
A so called young diesel technician took a look and said that the engine was shot and not worth fixing.
I was visiting a few weeks later and took a look.
If you know old Detroits, you know what's coming next.
The air box shutdown damper was closed.
There are a lot of different ways that the damper was operated depending on the application.
This one had a small governor that released the trip if it went over-speed.
It was completely inoperative.
The grease was so old that it was as hard as paraffin.
I spent two or three hours cleaning and re-lubricating the governor.
As far as I know it ran another 10 or 15 years.
It may be running still.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[nhcf]

Great feedback. Thanks everyone for your responses.