Note: Descriptions are shown in the official language in which they were submitted.
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Patent Application of
Radek Masin
for
TITLE: WASTE OIL BURNING SYSTEM
CROSS-REFERENCES TO RELATED APPLICATIONS
Not Applicable
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR
DEVELOPMENT
Not Applicable
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BACKGROUND OF THE INVENTION
1. Background - Field of the Invention.
This invention relates to the field of waste oil burning systems. More
specifically, the
present invention comprises a waste oil burning system having a preheated
atomizing air feed.
2. Background - Prior Art
Combustion is one of the preferred methods of disposing of waste oils such as
used
engine oils, cooking oils, cutting oils, gear oils, hydraulic oils, and other
difficult to burn liquids,
such as glycerin and antifreeze. Waste oils do not burn cleanly or efficiently
if the oil is not
properly atomized. To improve efficiency, many facilities that burn waste oil
preheat the oil.
Preheating the oil lowers the viscosity of the oil so that it may be more
readily atomized when
mixed with air (such as when sprayed through an atomizing nozzle).
There are many disadvantages to preheating waste oils, however. First, the
energy to
preheat waste oils can be costly. Also, even the most controlled preheating
processes can cause
acceleration of chemical reactions within the waste oils which result in
formation of deposits on
heating surfaces. The fouling of the heating surfaces results in heating
inefficiencies, requiring
the preheater to be regularly cleaned and maintained. Furthermore, some of the
deposits may
break free of the heating surface only to foul other parts of the burner,
including the nozzle and
combustion chamber.
Accordingly, it would be desirable to have a waste oil burning system which is
not costly
to operate and avoids the problems associated with the preheating of waste
oils.
SUMMARY
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The present invention comprises a waste oil burning system having a burner and
a heat
exchanger for preheating atomizing air before the atomizing air is supplied to
the nozzle. The
burner includes a fuel conduit for supplying waste oil to the burner and an
air supply line for
supplying atomizing air to the burner. The burner has a nozzle which atomizes
the waste oil by
mixing the waste oil with the air from the air supply line. The nozzle sprays
the atomized waste
oil into a combustion zone where the atomized waste oil is burned. An air-to-
liquid type heat
exchanger is positioned in the combustion zone, so that energy produced from
the combustion of
the waste oil preheats the air supplied through the air supply line before the
air is mixed with the
waste oil.
DRAWINGS
FIG. 1 is a schematic, showing the present invention.
FIG. 2 is a schematic, showing the present invention.
FIG. 3 is a schematic, showing the present invention.
REFERENCE NUMERALS IN THE DRAWINGS
storage vessel
12 waste oil pump
14 waste oil supply line
16 burner
18 storage vessel
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20 fuel pump
22 fuel supply line
24 combustion zone
26 air supply line
28 air compressor
30 fuel conduit
32 nozzle
34 heat exchanger
36 flame
38 waste oil burning system
40 waste oil solenoid
42 fuel solenoid
44 fuel solenoid
46 switch
48 timer
50 switch
52 timer
DETAILED DESCRIPTION
The present invention, waste oil burning system (38) is illustrated in FIG. 1.
Waste oil
burning system (38) may be used to burn various waste oils, including most No.
4 specification
oils. No. 4 specification oils generally include heavy distillate and blends
of distillate and
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residual fuel oils, typically having a carbon chain length of 12 to 70 atoms.
Storage vessel (10)
is provided for storing waste oils before they are burned. Waste oil pump (12)
is used to provide
a continuous supply of waste oil to burner (16) through waste oil supply line
(14). Although a
centrifugal pump is illustrated, the reader should note that any pump may be
used that is suitable
for transporting the waste oil at a controlled rate.
Air compressor (28) is provided to provide a continuous supply of atomizing
air to burner
(16) through air supply line (26). Air supply line (26) transports the
atomizing air through
combustion zone (24) where energy produced during the combustion of the waste
oils preheats
the atomizing air. A heat exchanger for preheating the air is positioned in
combustion zone (24)
and fluidly connected to air supply line (26). Heat exchangers of various
designs may be
employed for such a purpose. In the preferred embodiment, the heat exchanger
includes a
conduit or manifold which is heated by the energy produced during the
combustion of the waste
oils. As the atomizing air passes through the heat exchanger, the air is
heated.
During start-up, a starter fuel feed is mixed with the waste oil feed for a
period of time
until the heat exchanger reaches the designed operating temperature. Storage
vessel (18) is
provided to maintain a supply of starter fuel sufficient to facilitate the
combustion of the waste
oil while the heat exchanger is brought to operational temperature. Fuel pump
(20) supplies
burner (16) with a continuous feed of starter fuel during start-up through
fuel supply line (22).
As illustrated in FIG. 2, burner (16) includes nozzle (32) which is configured
to atomize
the waste oil by mixing the waste oil with the air from air supply line (26).
Nozzle (32) is
configured to spray the atomized waste oil into combustion zone (24) where the
waste oil is
combusted, as indicated by flame (36). Nozzle (32) is preferably an external
mix nozzle, but an
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internal mix nozzle may also be used. Those that are skilled in the art know
that the term
"external mix nozzle" describes a class of nozzles in which air is mixed with
a liquid after the
liquid exits a discharge orifice. In external mix nozzles, the nozzle opening
is generally coaxial
with the liquid discharge orifice. A pressurized air stream is typically
directed on the
discharging liquid stream so that the two components mix while passing through
the nozzle
opening.
Nozzle (32) has fuel conduit (30) which transports waste oil through nozzle
(32). The
waste oil mixes with the atomizing air as it exits fuel conduit (30). Nozzle
(32) sprays the waste
oil and air mixture into combustion zone (24) where the waste oil combusts.
Waste oil supply
line (14) and fuel supply line (22) both feed into fuel conduit (30). As
mentioned previously,
fuel supply line (22) supplies starter fuel during start-up. Once heat
exchanger (34) reaches
operational temperature, only waste oil is combusted.
In the preferred embodiment, air supply line (26) feeds air to burner (16),
then through
combustion zone (24), then back to burner (16) where the air is discharged
from air supply line
(26) into nozzle (32). Those that are skilled in the art will know that the
various materials and
designs may be used for heat exchanger (34). In addition, the dimensions of
heat exchanger (34)
and the distance of heat exchanger (34) from flame (36) may all be adjusted so
that the atomizing
air enters nozzle (32) at the appropriate temperature. In the preferred
embodiment, the atomizing
air is heated to a temperature of at least 200 degrees Fahrenheit prior to
entering nozzle (32). As
illustrated in FIG. 2, heat exchanger (34) may simply be a continuation of air
supply line (26)
which passes through combustion zone (24).
EXAMPLE
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Through experimentation it has been determined that waste oils having a flow
rate of
approximately 2.5 gallons per hour may be cleanly and efficiently combusted
when mixed with
atomizing air having a flow rate of 0.3 cubic feet per minute at a pressure of
7 psi and a
temperature of 250 degrees Fahrenheit. In the referenced experiment, an
external mix aspiration
nozzle was used to mix the waste oil with the atomizing air. The waste oil was
not preheated
prior to being mixed with the atomizing air.
For start-up, a combustion enhancer was mixed with the waste oil for improved
atomization and ignition. Also, atomizing air was provided at a flow rate of
0.8 cubic feet per
minute until the atomizing air reached a temperature of 250 degrees
Fahrenheit.
A control system for controlling the starter fuel and waste oil is illustrated
in FIG. 3. The
flow rate of waste oil through waste oil supply line (14) is controlled by
waste oil solenoid (40).
Two solenoids, fuel solenoid (42) and fuel solenoid (44), are arranged in
parallel to control the
flow rate of starter fuel through fuel supply line (22). Fuel solenoid (42) is
controlled by switch
(46) and fuel solenoid (44) is controlled by switch (50). Both switch (46) and
switch (50) have
three operating modes - "timed," "off," and "continuous."
During start-up, switch (50) may be adjusted to the "timed" mode so that fuel
solenoid
(44) opens and starter fuel is supplied for a period of time. Switch (50) is
electronically
connected with timer (52). Timer (52) is preferably adjustable so that the
timing period may be
changed as necessary. The period of time which fuel solenoid (44) is in the
opened position may
be experimentally determined to meet the requirements of the particular heat
exchanger and flow
rate of waste oil that is to be combusted. By the time fuel solenoid (44)
closes, the atomizing air
is hot enough to keep the burning process going without the aid of the starter
fuel.
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Switch (46) controls fuel solenoid (42). Fuel solenoid (42) controls the flow
of starter
fuel through a second fuel line. Switch (46) is electronically connected to
timer (48). The
second fuel line may be opened when larger amounts of starter fuel are needed.
If the waste oil
is very poor, either switch (46) or switch (50), or the two combined, may be
turned to
"continuous" mode so that a constant supply of starter fuel is provided
throughout the burn time.
It is also possible to turn off the supply of waste oil completely and burn
only starter fuel until
the desired operating temperature is attained.
The feed of starter fuel to burner (16) may also be controlled with a solenoid
integrated
with a temperature sensor and controller. A temperature sensor may be
positioned in the air
supply line downstream of heat exchanger (34). The temperature sensor may be
configured to
sense the temperature of the air before the air is mixed with the waste oil.
When the temperature
is less than 200 degrees Fahrenheit, the controller may open the solenoid to
supply starter fuel to
burner (16). When the temperature sensor observes an air temperature of at
least 200 degrees
Fahrenheit, the controller may close the solenoid in the starter fuel supply
line, cutting off the
starter fuel feed to the nozzle. It should be noted that the temperature
sensor and controller may
use a different set point than 200 degrees Fahrenheit.
In addition, multiple set points may be used to control the flow rate of
starter fuel. This
may be accomplished by using a solenoid that may be opened to various
increments. For
example, the solenoid may be set to a partially open position when the air
reaches 200 degrees
Fahrenheit. The solenoid may then be moved to a completely closed position
when the air
reaches 250 degrees Fahrenheit. Obviously, even more set points on solenoid
positions may be
incorporated to minimize the use of starter fuel.
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The preceding description contains significant detail regarding the novel
aspects of the
present invention. It should not be construed, however, as limiting the scope
of the invention but
rather as providing illustrations of the preferred embodiments of the
invention. As an example,
combustion zone (24) may be an enclosed fire box or it may be completely
external to burner
(16). Thus, the scope of the invention should be fixed by the following
claims, rather than by
the examples given.
