Increased Generator efficiency and life cycle extension - through prognostic health management

[KennyMSI]

Goal - to increase fuel efficiency in smaller generators ranging from 15 - 35kw through Condition Based Maintenance.

Are there COTS rugged sensor kits (kit of sensors)available for monitoring the efficiencies and provide prognostic health of small diesel generators. (15 - 35 KW)

Or what types of rugged sensors are needed to monitor air flow heat, vibration, power output efficiencies etc.

Rugged - as for use in Alaskan oil field generators or desert applications.


Are there certain sensors or combination of monitoring techniques that work better than others to accomplish the greatest saving and extending equipment life?

Does efficiency increase, if the geographical location of operation changes i.e. reduction or increase of average climatic temperature without changing altitude?

Is greater efficiency achieved if two or more units are combined parallel?

 

[waross]

I take it that you don't have much hands on experience with actual generators. Efficiency is what it is. A dirty air filter or partially plugged radiator may affect the efficiency. I have seen a dramatic increase in efficiency when a radiator was intentionally partially plugged. How are you defining efficiency? A generator running unloaded has about zero percent efficiency. Efficiency generally rises as loading increases. So, add a dummy load to increase efficiency, even though you are burning more fuel to drive the real load, the efficiency looks better on paper.
You won't see many generators of that size in the oil patch. You may see a lot of 6 kW or 8 kW sets on light towers. They use synthetic oil and change it every 1000 hours, sometimes. (Whether it needs it or not!) Fuel consumption may increase 20% or 30% or more on really cold days. (-20 F or -30 F or colder.)
The real work is done by gen-sets in the mega Watt range. Winter fuel costs about a 10% loss in efficiency (depending on your definition) or a 10% increase in fuel consumption.

Is greater efficiency achieved if two or more units are combined parallel?
Compared to what??

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

 

[KennyMSI]

Thank you, Bill for the reply.

I am looking for answers across the board.

Efficiency in this scenario equates to reduced Life cycle costs across the spectrum of energy, time (man power, downtime, etc), and money.

The units are 15 - 30kw, in mobile off grid application which requires them to run 24/7 when needed for days, weeks or months at a time, at low load in far less than optimal location and weather conditions, until called upon on at any moment. These conditions result the draw backs you have mentioned. The goal is to make sure that the units are ready to step up to the plate when called upon.
The drawbacks of running at low load as you have mentioned correspond with reduce the lifecycle and efficiency.

Dummy loads as you mentioned waste fuel.

In this scenario, fuel is precious and highly trained techs are not readily available, making efficiency a priority. Additionally, it is a mobile application which requires the load itself to be mobile. This increases manpower and transportation costs.

What are some of the other issues that are created in these on/off, in-use/stored, “no or low load conditions”

Thank you for the feedback.
Kenny

 

[waross]

Use a 6 kW light tower to supply a couple of kW for heat and battery charging for the larger set. Design enough heat so that the large set will start dependably when needed. The light tower may use less fuel than the larger set uses at no load. The life of the larger set will have a greatly extended useful lifetime. (In years. About the same life in hours.)
Setup will not be a great drain on either technical expertise, special knowledge or cost. Payback will be in less hors on the larger sets, and possibly less fuel costs.
Hint: Make efforts to maintain proper operating temperature of the lighting towers. Rad shutters and enclosures. Consider running one or two lights 24/7 in extremely cold weather to help load up and keep the operating temperature up.


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

 

[KennyMSI]

Interesting approach.

To clarify: You are suggesting using two generators. a smaller generator (6 – 8kw light tower) during low peak times and as a battery charger and block heater (if needed) for a larger unit. This will offer great efficiencies at low load. Then when high load demand is present the 15 - 35kw generator is prepared to be quickly brought online allowing it to be used/run with great efficiency.

This is required due to the nature of diesel generators being inefficient at loads less than 75% of available output.

These issues are easier to overcome on smaller generators through electromechanically (shuttering or enclosing) maintaining optimum operating temperate of the light tower because it is smaller?

Are there any two stage generators on the market?

 

[waross]

Sorry for the delay. My six year old son is a rodeo nut and we just got back from a weekend of rodeo.
Forget about the generator end. Your issues are overwhelmingly with the diesel engines. Diesel engines don't like light loads and don't like to run cool.
As the load on the engine increases the pressure in the cylinder increases. Many piston rings are designed so that the pressure of combustion acts to expand the ring and increase the force of the ring on the cylinder wall. Running with a light load and the resulting light ring forces may lead to oil pumping, or cylinder glazing, which will lead to worse oil pumping.
Efficiency. An engine needs a certain amount of fuel to keep spinning at synchronous speed. At light loads this may exceed the amount of fuel used to drive the load. Very poor efficiency. Do the math.
If the engine is too cool, the heat losses become noticeably great. In order to keep the engine turning at synchronous speed, the governor must supply enough fuel to make up the heat losses as well as enough to keep the engine turning. At minus 30 degrees, heat losses may more than double the fuel consumption of an unloaded engine.

Another large saving in service costs may be realized by using semi synthetic oil. There are grades of semi synthetic oil that will extend the oil change interval of an engine in this size range from the normal 250 hours to 1000 hours. That may be a pretty big saving in labor and transportation if you are responsible for servicing isolated plants across the Alaskan wilderness.


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