Note: Descriptions are shown in the official language in which they were submitted.
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The present invention is an instant steam generator.
The invention provides a compact unit having no boiler
which can be used on site to generate various qualities of
steam for a variety of applications. For example, khe
invention has particular application for curing
prestressed and precast concrete and generally for the
standard curing of concrete products such as bloeks or
pipes. During curing of concrete products 7 it is
desirable to maintain a uniform temperature throughout the
concrete and to maintain the surface of the concrete
moist. The concrete curing process generates heat, which
tends to warm up the inside of concrete products. By
stacking the ooncrete blocks or other items in a room and
then ~ubjecting them to steam, one simultaneously achieves
the two objects of maintaining the blocks at a uniform
: curing temperature and maintaining them moist. By curing
the blocks in this fashion, one can obtain, for example~ a
28 day cured concrete ~trength in 24 hours.
A desirable Peature for an instant steam generator
is that it has a low carbon monoxide output. A low carbon
monoxide output is essential where the steam generator is
operated in an enclvsed facility, for example, in a
concrete products plant or in a mine, in order to meet
typical government reguIations for worker exposure to
carbon monoxide.
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~he ~nvention employs ~ unique combu~tion chamber
and water vaporization combination wher~by the combustion
chamber i6 cooled by a surrounding jacket of circulating
water~ and the outflow of water from the ~acket i6 used as
S the source of water to be vaporized by combustion gases
from a burner located at one end of the chamber. The
present arrangement differs from that previously known,
for example as described in U.S. Patent No. 4,211,071-
Wyatt, July 8, 1980, by introducin~ a spray of water
10 countercurrently to the stream of combustion gases exiting
the combustion chamber. This arrangement creates a great
deal of turbulence in the area surrounding the water spray
thus ensuring instant and thorough vaporization of the
spray by the combustion gases. In prior devices, e.g.
15 Wyatt, water flows through a jacket around the combustion
chamber and is then discharged through an annulus around a
flame-enclosiny shield so that the water flows with the
hot gases cocurrently through the combustion chamber. In
practice, it has been found that this cocurrent flow of
20 water ab~ut the flame leads to flame instability and
quenching which causes the formation of unacceptably high
levels of carbon monoxide in a poorly ventilated work area
about the generator. By introducing the water spray in a
region remote from the burner flame, the problem of flame
25 quenching is eliminated. The use of the water cooled
jacket for the chamber obviates the need to use refractory
material to line the chamber and provides the added
benefit of preheating the water for vaporization.
In accordance with the present invention, there is
30 provided a steam generator, comprising a water jacketed
co~bustion chamber having an inlet and an outlet for the
circulation of water through the jacket and having first
and second ends. A burner is positioned in the first end
of the combustion chamber. Means are provided for
delivering pressurized air -and fuel to the burner so that
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the burner may produce ~ ~lame extending toward the ~econd
end of the combustion chamber. A water ~pray nozzle i6
positioned at the ~econd end of the combustion chamber
remote from the burne~ flame, ~aid nozzle being connected
to the outlet of the jacket and being adapted to spray
water countercurrently into a ~tream of hot gases from the
burner flame thereby creating steam without quenching the
flame. A discharge conduit is connected to the second end
of the combustion chamber for conveying the steam so
generated. Thus, the present invention employs a unique
arrangement in which the water is sprayed countercurrently
to the flow of hot gases, and the water spray nozzle can
be pointed directly at the burner. This arrangement is
contrary to conventional teachings which specify that the
water should be sprayed away from the flame to avoid flame
quenching.
In fact, it has been found that by spraying water
directly at the combustion gases coming from the burner
flame, extremely efficient steam generation can be
achieved. It is believed that this arrangement promotes
turbulPnce between the water spray and the hot exhaust
gases, thereby effecting an instant heat transfer to the
water spray creating steam. It has been found,
surprisingly, that steam generated in accordance with the
invention does not result in flame quenching even when
producing steam at pressures much higher than those
a~hievable by prior devices. This result is obtained by
introducing the water spray into ~ region of the device
which is remote from the burner flame so that the water
spray does not interfere with the combustion process at
the burner. Since fuel combustion is not affected by the
water spray in the present invention, a device equipped
with an efficient burner may produce a sufficiently low
level of carbon monoxide to be suitable for use in
enclosed work areas.
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A preferred embodiment of the invent~on will
here.inafter be described with reference being made ~o the
drawings in which:
Figure 1 i6 a perspectiv2 view of the generator
S partially exploded and partially broken away for clarity;
and
Figure 2 is a vertical sectional view of the
combustion chamber and associated components.
It should be appreciated that although the drawings
show an arrangement suitable for a natural gas or propane
burner, an oil burner can also be used with the invention
by making appropriate changes to the air and fuel supply
means known to those skilled in the art.
The steam generator of the present invention
comprises a combustion chamber 10 having a burner 11 at
one end and a water spray nozzle 12 at the other end. The
chamber 10 is provided with a water jacket 15 ~Fig. 2)
having a jacket inlet 16 near the lower end of the chamber
10 and a jacket outlet 17 near the upper or burner end of
the chamber 10. Wat~r is circulated through the jacket 15
at a rate of circulation governed by water pressure
controls 19 which are readily available and which are
inserted into the water inlet line 20. Water exiting the
jacket 15 proceeds through the jacket outlet 17 and a pipe
22 to the water spray nozzle 12 which is in turn located
within a steam outlet line or discharge conduit 24. The
combustion chamher 10 is sized to enable complete
combustion of the fuel by the flame of thQ burner 11
within the confines of the chamber 10. Indeed, as shown
in Fig. 2, it is preferred to have a zone 25 in the lower
portion of the combustion chamber 10 for thP hot exhaust
gases of combustion with fuel combustion occurring to the
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~ullest extent allowed by the mechan~c~ o~ the burner 11
in a zone 26 in the upper portion of the chamber 10 about
the flame.
The burner 11 is a~ oil burner or preferably a
burner of the type which burns a pressurized gaseous fuel
~ixtur~ euch as air and natural gas or propane.
Accordingly, the burner 11 is provided with an inlet
conduit 30 comprising a larger diameter inlet air pipe 31
for pressurized air, into which is joined a fuel pipe 32
lo of a lesser diameter. The junction point 33 of the pipes
31 and 32 is just upstream of a venturi 35. The gaseous
fuel mixture is thoroughly mixed by flowing through the
venturi 35 thereby ensuring even combustion at the burner
head 11 and affording good control of the heat output
therefrom.
The air supplied to the inlet air pipe 31 is
pressurized in a conventional manner by drawing air in
through a filter 40 and passing it through a blower 41 or
other well known compression means. Pressure in the inlet
air pipe 31 may be regulated by use of an appropriate air
pressure valve 42, and pressure in the fuel pipe 32 may be
controlled by a conventional fuel v~lve 43. By adjustment
of the valves 42 and 43, the pressure and composition of
the fuel mixture can b~ varied as desired.
I~nition of the burner 11 may conveniently be
accomplished hy use of a pilot 49 located adjacent the
head of the burner 11. The pilot 49 may receive a ~uel
mixture ~rom feeder lines 50 and 51 taken ~rom the main
fuel pipe 32 and the inlet air pipe 31. The feeder lines
50 and 51 tap the main pipes 31 and 32 at points upstream
¦ of the respective valves 42 and 43. The feeder lines 50
a~d 51 are also pr~vided with valves 53 and 54 so that the
desired combustion gas mixture and pressure can be
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provided to the pilot 49.
It ~ill be apparent to the person skilled in thi6
art that any of a number of different kind~ of burner~
would be suitable for use in the present invention. Since
the steam generated by the present device contains the
exhaust from the burner 11, it may be particularly
desirable in certain applications to choose a burner 11
which produces a low level of carbon monoxide. The low
carbon monoxide level of the burner 11 will be retained
during the steam generating process using the present
device, because there is no flame guenching produced by
the countercurr~nt spray sf water from the nozzle 12.
Likewise/ the foregoing description of the fuel and air
supply means is illustrative and may be varied with the
type of burner used. It will also be apparent to th~se
skilled in this art that central control means may be
employed to cooxdinate the flows and relative pressures of
the fuel, air and wa~er streams for the overall system.
In operation, steam is generated by the mixture of
the water spray from the water spray nozzle 12 with the
hot combustion gases produced by the burner 11 at the
lower end of the combustion chambèr 10. By causing the
spray from the water spray nozzle 12 to be directed
countercurrently to the ~xhaust gases from the burner 11,
instant vaporization of the water occurs due to the
extreme turbulence and thorough mixing of the opposing
streams. Turbulence and mixing of opposing streams may be
modified by the insertion of baffles in the combustion
chamber 10 and in the steam ~utlet line 24. The quality
of the steam exiting through the steam outlet line 24 may
be determined by adjusting the output of the burner 11 and
the output o~ the water spray nozzle 12. The relative
opposing pressures from the burner 11 and the spray nozzle
12 must be adjusted to enable steam to be generated in the
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~anner described, ~hat i~, by vaporiz~tion of the wa~er
con~act~ng the hot exhaust gases from the burner 11. The
generation o~ relatively low pressure tea~ i. e. 5-20
psi, i5 accomplished using the invention wherein the water
vaporization occurs virtually entirely within the outlet
neck 59 located between the lower end of the combustion
chamber 11 and the steam outlet line 24.
The principles of the inventi~n as ~escribed may be
utilized to generate steam of much higher pressure than
heretofore was thought possible using a direct fired
generating device. Thus, while the foregoing has
disclosed a preferred embodiment, it is not intended that
this disclosure b~ construed as restricting the scope of
the invention which is defined in the following claims.
