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The burning of
alcohols with the object of extracting the thermal energy in
reacting to the concerns for
global warming and the
consequential impact on life in general coupled with the
occasional spikes of the prices of
crude oil, is deemed a viable option in the quest for alternative
fuel to fossil fuels. Adoption of alcohols as an alternative fuel
must then be implemented both at the home-heating application as
well as in large scale combustion for supporting
distributed power generation systems such as by utility
corporations. However,
the existing oil and gas fuel burners may not necessarily support
the complete oxidative combustion of green alcohols which often is
derived by various fermentation process and as such have different
constituents by-products and including possibly water; hence
new
burner requires a set of thoroughly considered development
specifications, as presented in the analysis.
Effectively, the primary
equipment for an Ethanol Fuel Burner, being adapted from the
vegetable oil fuel
burner consists of three
integrated components:
- Fuel Combustion Burner
- Fuel Burner Base (or
Enclosure)
- Combustion Chamber
which are interfaced with
secondary accessorial equipment, a Fuel Delivery System, consisting
of Storage Tank, and a small pump that pumps the fuel into the Fuel
Burner Base. The pump should also
be fitted with real-time control to activate pumping only with fuel
available in the Storage Tank.
The Fuel Combustion Burner
should only be a use-specific customized variant of the basic
fuel combustion burner
technology of the combustion technologies. One of the
customizations stems from the evaluation of the impact of the water
content of the fuel in the determination of the value Fuel-Air
Mixing Zone, FAMZ, "h" - the maximum range of travel from the fuel
atomization point, or fuel injector tip, to the entry into the
chamber is determined by the latent heat of vaporization required to
make gaseous all the fuel droplets of the atomization; and in the
case of green ethanol, which ordinarily forms an azeotrope with
water, this heat of vaporization will vary as the water content
varies: the more the water content is the higher the heat of
vaporization and the longer the travel distance, FAMZ, "h"
must get. In effect, both the choice of alcohol as fuel and ethanol
production process impacting the water content directly affects
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the FAMZ, the vaporization
zone length, "h". This consideration is critical, because this
dimension al length property directly impact the performance of the
Fuel Combustion Burner - the device that actually delivers the fuel
into the combustion chamber - and as such should be designed to
accommodate the characteristic fluid properties of each fluid
type as well as mixed-alcohols fuel types particularly of the fuel
produced from
edible waste.
The
mixed-alcohols fuel types
presents a very unique issue as well, given that, an effective
or weighted latent heat of vaporization has to be calculated and
then applied in the overall design of the required heat of
vaporization. The effect of the presence of the other alcohols on
the effective thermodynamic properties of the fuel must also be
determined and incorporated into the computational evaluation of the
design data.
Additionally for ethanol fuel,
the effect of the water content in the fuel must also be evaluated
in terms of the corrosion of the walls of the FAMZ. Clearly the
water vapor that forms from the vaporization is most likely to
corrode the walls. Engineering to prevent such possibility
might make it necessary to stipulate the inner walls of the mixing
cylinder to be made of precious metals or ceramic coated cylinder.
The Fuel Burner Base (or
Enclosure) has two inlet
ports: fuel inlet port, and air-inlet port, as with the vegetable
oil fuel burner, and nothing else. However, the casing of the Fuel
Burner Base must be such as to support high pressure operation: The
presence of water requires more air to support the vaporization of
the fuel droplets makes it necessary to operate the Fuel Burner at
relatively higher pressure, because high pressure attendant of the
high air flow-through required.
The Combustion Chamber for a
simple Burner suffers very little customization from the chamber for
the vegetable oil fuel burner. A reasonable customization may simply
aim to have the air-feed into the chamber be preheated with the
exhaust of the effluent. This is readily accomplished by having the
outlet of the Chamber connected to a heat exchanger and have the
inlet air preheated with the outlet air in the heat exchanger. |
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