193
Dimethyl Ether
that of diesel in the test by adding certain substances. Shown here are a commercial lubricity additive for diesel fuel, castor oil, and rapeseed oil methyl
ester (RME). Even though the wear with pure DME is high, it still lubricates
somewhat, and has better wear characteristics than no lubricant at all.
It is interesting to note that RME is a lubricity improving agent. Vegetable
oil methyl esters are very good diesel fuels (Scholl and Sorenson 1993), come
from renewable sources, and should be cheaper than the commercial additives. Thus, a larger amount of RME could be used than other additives. The
effects of RME on combustion and emissions in DME are not known. It is
likely that there is a limit, since pure vegetable oil and its methyl esters will
produce carbon particles when used as pure fuels.
However, experience has shown that even though DME satisfies this test,
unacceptable wear can occur in some systems (Nielsen and Sorenson 1999).
Thus, since DME is different than diesel fuel, the accepted test procedure
does not appear adequate to certify suitability of DME fuel for fuel injection
equipment. Currently, there are too few published studies to see how different systems and materials respond to the different additives, and enable a
simplified laboratory test for lubricity.
Special fuel injection systems that take DME’s special characteristics into
consideration are being developed for DME engines (McCandless et al. 2000),
but the long-time durability of these systems still needs to be established.
Fleet tests of diesel engines converted to DME and running on different
kinds of commercial pumps with lubricity additives have accumulated tens
of thousands of km, so development is underway (Sato et al. 2008). However,
there is still a need to develop new materials for the pumps and new better
lubricity additives especially for DME.
6.4.2 Power generation and industrial Burners
Since a DME diffusion flame does not produce soot particles, DME is also
a natural candidate for use in a gas turbine or other industrial boiler, since
these devices also operate with diffusion flames. DME has been successfully
tested in gas turbines using injection of both liquid and gaseous forms of
DME (JDF 2007). Fuel injection nozzles were modified or specially designed
to accommodate the special properties of DME. Tests with gas turbines up to
25 MW indicate that DME can be operated in a gas turbine, with the potential for low NO x emissions, and emissions levels of CO and unburned fuel
comparable to those of conventional turbine fuels such as oil, natural gas,
and LPG. As is the case with diesel engine operation, there is no soot emission. At least one manufacturer of gas turbines has approved their operation
with DME (Basu and Wainright 2001).
DME has also been shown to be a suitable replacement fuel for other types
of industrial boilers. In a retrofit mode, DME has been successfully tested
with mixtures of heavy fuel oil and coal. Operation with about 33% DME
mixed with coal in an industrial boiler has also been demonstrated. Lower
Dimethyl Ether
that of diesel in the test by adding certain substances. Shown here are a commercial lubricity additive for diesel fuel, castor oil, and rapeseed oil methyl
ester (RME). Even though the wear with pure DME is high, it still lubricates
somewhat, and has better wear characteristics than no lubricant at all.
It is interesting to note that RME is a lubricity improving agent. Vegetable
oil methyl esters are very good diesel fuels (Scholl and Sorenson 1993), come
from renewable sources, and should be cheaper than the commercial additives. Thus, a larger amount of RME could be used than other additives. The
effects of RME on combustion and emissions in DME are not known. It is
likely that there is a limit, since pure vegetable oil and its methyl esters will
produce carbon particles when used as pure fuels.
However, experience has shown that even though DME satisfies this test,
unacceptable wear can occur in some systems (Nielsen and Sorenson 1999).
Thus, since DME is different than diesel fuel, the accepted test procedure
does not appear adequate to certify suitability of DME fuel for fuel injection
equipment. Currently, there are too few published studies to see how different systems and materials respond to the different additives, and enable a
simplified laboratory test for lubricity.
Special fuel injection systems that take DME’s special characteristics into
consideration are being developed for DME engines (McCandless et al. 2000),
but the long-time durability of these systems still needs to be established.
Fleet tests of diesel engines converted to DME and running on different
kinds of commercial pumps with lubricity additives have accumulated tens
of thousands of km, so development is underway (Sato et al. 2008). However,
there is still a need to develop new materials for the pumps and new better
lubricity additives especially for DME.
6.4.2 Power generation and industrial Burners
Since a DME diffusion flame does not produce soot particles, DME is also
a natural candidate for use in a gas turbine or other industrial boiler, since
these devices also operate with diffusion flames. DME has been successfully
tested in gas turbines using injection of both liquid and gaseous forms of
DME (JDF 2007). Fuel injection nozzles were modified or specially designed
to accommodate the special properties of DME. Tests with gas turbines up to
25 MW indicate that DME can be operated in a gas turbine, with the potential for low NO x emissions, and emissions levels of CO and unburned fuel
comparable to those of conventional turbine fuels such as oil, natural gas,
and LPG. As is the case with diesel engine operation, there is no soot emission. At least one manufacturer of gas turbines has approved their operation
with DME (Basu and Wainright 2001).
DME has also been shown to be a suitable replacement fuel for other types
of industrial boilers. In a retrofit mode, DME has been successfully tested
with mixtures of heavy fuel oil and coal. Operation with about 33% DME
mixed with coal in an industrial boiler has also been demonstrated. Lower