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Biodiesel fuel production as a
means of addressing high prices of fuels produced from fossil fuels
is a main stream hobby at the moment and is being
researched at the
commercial scale as well. In consideration of this interest on the
fuel as an alternative energy source for such situations involving
ready use automobile fuel, the underlying technologies have been analyzed,
beginning
with algal oil feed biodiesel production process
for
producing biodiesel from algal oil. This process was analyzed with
the view of the feed-oil as containing no
amphiphiles,
though amphiphiles, soap
were produced post-transesterification when Free Fatty Acids are
present in the oils. However, while the algal oil does not have
amphiphiles there are other oils - amphiphilic oils such as Soy Bean
Oils - from which biodiesel may also be produced that contain
amphiphiles. For amphiphilic oils then the process analyzed for the
production of biodiesel from algal oil has to be modified to include
sub-process for removing, "washing" or purifying the feed-oil, as
the presentation elicits.
The production of the amphiphiles
in course of the transesterification reaction generally results in
the washing - removal of the amphiphiles with
water or
adsorbents
or both - of the biodiesel for suitability for use in
engines. Given the proven viable removal of amphiphiles from organic
fluid, amphiphilic oils, also can be washed. However, when the
amphiphilic oils, such as Soy Bean Oils are being used as feed-oils
for producing biodiesels from which amphiphiles must be washed, then
such feed-oils which contain amphiphiles present the additional consideration of
"washing" not just the process product of biodiesel but also the
process feed-oil even before the
transesterification process.
The removal of the amphiphiles
produced during the transesterification reaction as a result of FFA in the feed-oil, however, have been analyzed as
more efficacious with the
bubbling of the fluid through the water instead of
the water through the fuel as
often practised. This approach still offers the best
choice even in this case of washing oil over waterless washing, even though the amphiphiles
in this case is not soap but are phospholipids: Research has shown
that
phospholipids is structurally very polymorphic
- assuming different shapes depending on the ratio of lipids
present, temperature, hydration, pressure and ionic strength and
type - in water mixtures. Hence, the mist wash approach, giving rise
to the description of "washing" would result in the polymorphism of
the phospholipids inside the amphiphilic oils that would make the
purification impossible to accomplish.
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However, within the context of
the fluid-bubbling washing the
polymorphic nature of the phospholipids is not very relevant to the
consideration given that once removed from the oil, the polymorphic form
which the
lipids assumes is of no consequence to the biodiesel production.
Besides, the use of water washing over water-free washing, which is the use
of adsorbents, of the feed-oil would result in very oily messy
pellets, the disposal of which constitutes an entirely different set
of environmental issues, that the use of water does not.
All considered then, the
essential modification of the algal biodiesel process, as adaptation
for use with amphiphilic feed-oils, is the
inclusion of another washing process at the Algal Oil Extraction
step. This thrust effectively reduces the issues of analysis here to
that of the configuration
of feed-oil washing separator sub-process.
Feed Washing Separator
Configuration
The
Washing Feed-oil Separator sub-process configuration effectively consists of two main
process equipment: a Continuous Water Washing Feed-oil Separator for
the primary washing of the feed-oil and is based on the technology
of the continuous water washing biodiesel separator,
Electrostatic Liposome Separator for recovering the phospholipids
for sale to pharmaceutical industries for use as vehicles for drugs
delivery within the human body. However, the primary focus is on the
former.
The Continuous Washing
Feed-oil Separator, unlike the counter-current flow Continuous Water
Washing Biodiesel Separator
technology on which it is based, is a
co-current flow separator and with the configuration to support that
dynamic: The design consists of a cylindrical pipe capped at
both ends. Each cap has an outlet at the center with a relatively
smaller pipe attached. A short distance from the bottom is attached
laterally a tube extending into the pipe and bent into an L with the
open end of the foot of the L pointing upwards; the section of the
tube outside of the pipe is connected to a pulsating pump that is
connected to a container holding the feed-oil due for wash. Also
laterally, about
the top of the cylinder - a short distance below the design specified
axial-location of the oil-water interface from the bottom - is affixed a small
pipe connected to a pump which is also connected to the storage for
the Electrostatic Liposome Separator. The opening of the top cap is connected to the
washed Feed-oil Storage Tank; and the opening of the bottom cap is connected
to a pump which is also connected to the water main.
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Washing Biodiesel Operation
Obviously from this
configuration, when the amphiphilic feed-oil is pulse-pumped into the main cylinder
filled with water to the design-specified level slightly above the lateral
pipe affixed towards the top of the cylinder-body, spherical balls of
feed-oil gets
discharged (or sparged) separately because of the pulsation of the pump, and each
ball should float upwards. As the droplet travels upwards, the
amphipathic
electrostatic dynamic between the water molecules and the
amphiphiles obtains. On reaching the top of the water surface
the oil droplets should break up and coalesce into a layer of feed-oil.
This layer should be free of the amphiphiles, except at the
oil-water interface where the amphiphiles should congregate with the
hydrophilic groups jutting into the water and the hydrophobic ends
placed within the oil. Ultimately, depending on the water
temperature being at the being equal to the Critical Micelle
Temperature, CMT, or Krafft Temperature, and the number of water-oil
interfacial amphiphiles being greater or equal to the Critical
Micelle Concentration, CMC, amphiphiles get completely pulled out of
the oil medium into the water and assumes one of the many
polymorphic structures characteristic of phospholipids. In general,
the operation must aim to support the prevalence of the CMC and the CMT.
Meanwhile, at the same time,
water is continuously pumped out from the lateral pipe just below
the water-oil interface
effectively removing the water in which liposomes or some
polymorphic form(s) of the phospholipids will have formed; an
equal quantity of water is also continuously pumped into the
cylinder through the bottom
cap inlet-pipe, effectively keeping the water level constant.
At the same time, as the level of feed-oil rises up to the outlet of
the top cap, the oil also gets pumped out into the Storage
Container, effectively completing the washing process.
The purified or washed or
amphiphiles-free feed-oil is then subsequently used in the
production of biodiesel as per design requirements. |
