I'm doing some research on a suitable engine for a generator /
heater role and am curious how many hours before overhaul people have
been observing on their rotaries. In addition, which component is the
weak point and what methods can be taken to alleviate it?
Aaron Buster
Master's student at Clemson University
A few years ago Mazda built some engine with 3 piece apex seals.
When the slot in the rotor got worn the seals would roll out of the
slots at 200,000 miles or so. Especially with the turbo engines. Other
than that there are lots of NA rotary powered cars with over
300,000 miles.
I had a couple myself.
In aircraft use nobody has worn out an engine yet and I have
heard of gyro engines with 2500 hours. Most have way less than 3000
hours.
With silicon nitride seal the projected life life of the seal and rotor
housing is 20,000 hours. Rather extraordinary. You still have some
wear on
the side seals and the oil scraper rings. My guess is 3000 to 4000
hours on
those using Mobil 1 synthetic or Idemitsu rotary engine oil.
Of course the rotary is missing a lot of parts that are normally
subject to wear like
cam shafts and valves.
BTW The TBO for aircraft piston engines is really an inspection
of the steel moving parts that are subjected to fatigue. The
rotary is more like
an electric motor in that regard with no parts subjected to
reversing stresses.
Paul Lamar
Thanks for the info. I also found a group in Hiroshima using a biogas
that got 12,000 hrs out of theirs with no problems, but they didn't
mention what type of seals they used.
Another question: What is the maximum compression ratio of the 13B
geometry? Do I presume correctly that eccentricity is the limiting
factor?
http://www.igu.org/IGU%20Events/igrc/igrc2011/igrc-2011-proceedings-and-presentations/poster%20paper-session%201/P1-07_Kunio%20Kitano.pdf/
<http://www.igu.org/IGU%20Events/igrc/igrc2011/igrc-2011-proceedings-and-presentations/poster%20paper-session%201/P1-07_Kunio%20Kitano.pdf/>
Aaron Buster
Ingersol Rand was rumored to get 30,000 hours out of this big one
running on nat gas at 1500 RPM.
Paul Lamar
a 440ccm 20kW Wankel genset on natural gas ran in tests more than 20k
hours, then 1/4 of the allowed wear was done. On extended full power test
with turbocharged engines only ceramic seals were found ok.
rotaries didn't fail in a catastrophic manner, they didn't start when
defective! When an apex seal breaks only the power will be reduced,
but you
can't start it again.
failure is very easy to find out: augmented oil consumption is the
master sign ;-)
c l jaeggi
Who did this testing? What is the source of your information?
Squirt some heavy oil in the spark plug hole and it will start again.
Here in California natural gas is burned off at the well. The law
states: if you generate electricity connected to the grid the power
company must pay you for the power. Every well owner with waste NG
could then
buy a Wankel Gen set and receive a check from the power company.
Quote.
https://www.sce.com/wps/portal/home/residential/generating-your-own-power/net-
<https://www.sce.com/wps/portal/home/residential/generating-your-own-power/net->
-------------------------
"Net Energy Metering (NEM) is a program designed to benefit our
customers who generate their own electricity using eligible renewable
technology.
The NEM program uses a bi-directional meter to track the "net"
difference between the amount of electricity you produce and the
amount
of electricity you consume during each billing period. This can be
accomplished on a cumulative basis or on a time-of-use basis,
depending
upon your rate schedule.
As a Residential/Small Commercial NEM customer, you will continue to
receive monthly bills, but only for non-energy related charges such as
taxes and fees. On an annual basis, you will be billed for electricity
based on your net use for the previous year – for example, the
amount of
electricity you used minus the amount you generated. Large
Commercial/Industrial NEM Customers will continue to receive monthly
bills, which will require payment of the monthly non-energy related
charges (taxes and standard billing fees) and “Net” energy charges."
-------------------------
End quote.
See attached chart. Lets say it is 20 cents per KWH.
Net power out of a 50 HP gen set would be about 18KWH.
At 20 cents a KWH that is $3.60 and hour.
A AIXRO Wankel cost $5,500
Therefor it must run only 1500 hours to pay for the engine not including
the generator. Looks like a viable option if you own an oil well
and are burning off NG. Common in SoCal.
A used RX8 engine would be much cheaper, generate more power
and may make money at the rate of $15 an hour.
Paul Lamar
Hello Paul,
Does California companies burn off all the gas or flare some? Here in
Alberta the gas wells usually flow through a separator to drop out the
liquids that also come up. The liquids can then be put back in to flow
to a plant after gas flow measurement or shipped by truck or rarely
in a
separate pipeline. Turner Valley was the first oil field in Alberta
that
got in production almost 100 years ago. They were after the oil as
there
were not gas furnace and water heaters at the time. Infrastructure at
the time was coal so the gas was a byproduct with little value so they
flared it. The light at night could be seen in Calgary 40 miles away.
Turner Valley did not need street lights. After 40 years of burning
off
the gas, the field became unproductive as there was almost no pressure
left to cause the oil to flow up the wells. Now 30 years later, they
flow the oil wells for 2 or 3 days and shut them off for 5 to 7 days.
The pressure builds up a bit in that time and then falls off while
flowing. The operators rotate the flowing and resting wells. My grand
father was the machine shop foreman from the late ´30s? until his
retirement.
Dale Davies
If you ran the RX8 engine on NG and did away with the electric
motor that operated the main oil pump it would be more efficient
over all.
Flair or burn.
Paul Lamar
endurance tests was made by wankel-rotary AG.
the big ingersoll-rand rotary runs a lot more than 30k hours as
pipeline gas compressor, since 1978 in northern arctic!
c l jaeggi
Where in the arctic? Do you have any pictures?
Paul Lamar
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