199
Dimethyl Ether
appropriate. An examination of the use of LPG-based equipment for DME
has shown that existing LPG handling standards in the Netherlands need
to be modified slightly to accommodate DME (Elbers and Logtenberg 1999).
The most important issues were those of assuring that the sealing material is
compatible long-term with DME, and taking measures to maintain a maximum of 86% liquid in the container when filling. A nominal value of 80%
is appropriate. This filling amount is needed to prevent high pressures if
storage temperatures become too high and the liquid density decreases to
the point where there is all liquid in the tank. Above this point the pressures
could become very high, compromising the integrity of the container. LPG
has a similar restraint, with different allowable values of filling percentages,
depending on LPG composition.
Many other aspects of safety have been investigated through the Japan
DME Forum (JDF 2007). Briefly, they found that DME is stable in storage, and
unlike other ethers, does not form peroxides. Explosion hazards of DME are
similar to or better than those of LPG, and a fire emanating from a simulated
tank rupture was less dangerous than the equivalent with LPG, since the
fireball is smaller and less luminous than that from LPG. The low luminosity
greatly reduces the radiation heating of the surroundings. The DME toxicity
to living organisms is very low. In general, DME was found to be at least as
safe as, and normally safer than, LPG, the latter being a commonly used fuel
throughout the world.
It should be mentioned that the DME molecule is polar, and that in fuel handling systems, care should be taken to remove any build up of a static electric
charge in DME fuel systems. Also, similar to natural gas, an odorant needs to
be added to DME to help users detect leakage. Sulfur compounds (mercapatans) are typically used. DME produced from syngas is sulfur-free.
6.8 Future Scope
DME has been found to be an attractive fuel for combustion in a variety
of applications. It is an excellent diesel fuel substitute, producing no smoke
and permitting engine operation at very low NO x emission levels. It can be
used in gas turbines, with equivalent power and lower emissions than those
of traditional fuels, and is suitable for domestic use for cooking or home
heating, either as a substitute for LPG, or as an LPG extender in LPG/DME
blends. DME could also be used as a hydrogen carrier for fuel cell systems,
and it will function directly in a fuel cell, though not as well as hydrogen. A
major advantage of DME is that it produces no smoke during heterogeneous
combustion, allowing more aggressive treatment of other exhaust emissions,
resulting in low emissions levels with simpler exhaust treatment technology
for diesel fuel engines.
Dimethyl Ether
appropriate. An examination of the use of LPG-based equipment for DME
has shown that existing LPG handling standards in the Netherlands need
to be modified slightly to accommodate DME (Elbers and Logtenberg 1999).
The most important issues were those of assuring that the sealing material is
compatible long-term with DME, and taking measures to maintain a maximum of 86% liquid in the container when filling. A nominal value of 80%
is appropriate. This filling amount is needed to prevent high pressures if
storage temperatures become too high and the liquid density decreases to
the point where there is all liquid in the tank. Above this point the pressures
could become very high, compromising the integrity of the container. LPG
has a similar restraint, with different allowable values of filling percentages,
depending on LPG composition.
Many other aspects of safety have been investigated through the Japan
DME Forum (JDF 2007). Briefly, they found that DME is stable in storage, and
unlike other ethers, does not form peroxides. Explosion hazards of DME are
similar to or better than those of LPG, and a fire emanating from a simulated
tank rupture was less dangerous than the equivalent with LPG, since the
fireball is smaller and less luminous than that from LPG. The low luminosity
greatly reduces the radiation heating of the surroundings. The DME toxicity
to living organisms is very low. In general, DME was found to be at least as
safe as, and normally safer than, LPG, the latter being a commonly used fuel
throughout the world.
It should be mentioned that the DME molecule is polar, and that in fuel handling systems, care should be taken to remove any build up of a static electric
charge in DME fuel systems. Also, similar to natural gas, an odorant needs to
be added to DME to help users detect leakage. Sulfur compounds (mercapatans) are typically used. DME produced from syngas is sulfur-free.
6.8 Future Scope
DME has been found to be an attractive fuel for combustion in a variety
of applications. It is an excellent diesel fuel substitute, producing no smoke
and permitting engine operation at very low NO x emission levels. It can be
used in gas turbines, with equivalent power and lower emissions than those
of traditional fuels, and is suitable for domestic use for cooking or home
heating, either as a substitute for LPG, or as an LPG extender in LPG/DME
blends. DME could also be used as a hydrogen carrier for fuel cell systems,
and it will function directly in a fuel cell, though not as well as hydrogen. A
major advantage of DME is that it produces no smoke during heterogeneous
combustion, allowing more aggressive treatment of other exhaust emissions,
resulting in low emissions levels with simpler exhaust treatment technology
for diesel fuel engines.