Note: Descriptions are shown in the official language in which they were submitted.
CA 02205452 2006-07-14
BOILER WITH DOWNCOMERS FORMING A PART OF SUPPORT STRUCTURE
FIELD OF THE INVENTION
The present invention relates to designs for boilers and more
particularly, relates to a design for a flexible tube boiler.
S BACKGROUND OF THE INVENTION
The use of boilers is well known in the art and many different
designs have been proposed. The boilers may be used for heating fluids such
as water, glycol/water mixtures, thermal fluids, etc. They may be used for
producing steam at low or high pressure by means of a heat exchange
with the hot gases that are the products of combustion.
Generally, furnace or boiler circuits that receive heat cause the
fluid to flow from a low elevation to a high elevation while the water or
other fluid is continuously circulated through the outflowing circuits to
down flowing circuits which are generally referred to as downcomers. All
such circuits generally originate at a common point which is known as a
header or drum and terminate at a common point in either a header or a
drum.
As therefore mentioned, many designs are known in the art.
However, there still exists a need for a flexible tube boiler design wherein
a high efficiency is achieved while having a structure such that they are
relatively inexpensive to manufacture.
BRIEF SUMMARY OF THE INVENTION
According to one aspect of the present invention, there is
provided a boiler comprising a front wall, a rear wall, a pair of opposed
side walls, a lower header, an upper header, a plurality of bent tubes
extending between the lower header and the upper header and being in fluid
communication therewith, a first upper horizontal conduit in fluid
communication with the upper header, the first upper horizontal conduit
being located proximate the front wall, a second upper horizontal
conduit in fluid communication with the upper header, the second upper
horizontal conduit being located proximate the rear wall, a
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second lower horizontal conduit in fluid communication with the lower
header, the first lower horizontal conduit being located proximate the
front wall, a second lower horizontal conduit in fluid communication
with the lower header located proximate the rear wall, a first pair of
downcomers, the first pair of downcomers being located adjacent the
front wall and being in fluid communication with the first upper
horizontal conduit and the first lower horizontal conduit, and a second
pair of downcomers located adjacent the rear wall, the second pair of
downcomers being in fluid communication between the second upper
horizontal conduit and the second lower horizontal conduit, the
arrangement being such that the horizontal conduits and the downcomers
define a frame for the boiler.
According to a further aspect of the present invention, there
is provided a boiler comprising a front wall, a rear wall, and a pair of
opposed side walls, an upper header, a lower header, and a plurality of
bent tubes extending between and in fluid communication with the upper
header and the lower header, each of the tubes having a profile
comprised of a first section exiting from the lower header, a horizontal
floor section, a riser section extending vertically upwardly adjacent
one of the side walls, a plurality of interconnecting U-shaped sections
extending between one of the side walls and a central vertical plane of
the boiler, and an entry section extending between an uppermost of the
U-shaped sections and the upper header.
In a preferred aspect of the invention, the bent tubes are
designed to have three different profiles. In a first section of the
boiler proximate the front wall thereof, first and second profile tubes
are alternated in a tangential manner. In a rearward section of the
boiler proximate the rear wall thereof, bent tubes having a first and a
third profile are arranged in a non-tangential manner. The arrangement
is such that combustion gases passing through the front section are
forced to flow in a longitudinal direction while in the rear section,
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they are permitted to flow upwardly through a passing lane into a
convection section of the boiler.
BRIEF DESCRIPTION OF THE DRAWINGS
Having thus generally described the invention, reference will
be made to the accompanying drawings illustrating embodiments thereof,
in which:
Figure 1A is a side elevational view, partially in a section,
of a boiler illustrating the flow of gases throughout the convection
zone;
Figure 1B is a view similar to Figure 1A showing an
alternative gas flow pattern;
Figure 2 is a side elevational view illustrating the fluid
circulation patterns in the boiler of Figure 1B;
Figure 3 illustrates, in side elevational view, a boiler
arrangement used to heat water;
Figure 4 is a cross-sectional view taken at the front end of a
steam boiler;
Figure 5 is a cross-sectional view of a steam boiler at the
rear end thereof;
Figure 6A is a rear elevational view of the rear wall of a
steam boiler showing a downcomer arrangement with provision for an
access opening;
Figure 6B is an elevational view of the front wall thereof;
Figure 7A is an elevational view, partially in the cutaway, of
a rear wall for a water boiler;
Figure 7B is an elevational view of the front wall thereof;
Figure 8A is an elevational view of a first tube profile for
use in a steam boiler;
Figure 8B is an elevational view of a first tube profile for
use in a hot water boile r
Figure 9A is an elevational view of a second tube profile for
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use in a steam boiler;
Figure 9B is an elevational view of a second tube profile for
use in a hot water boiler;
Figure 10A is an elevational view of a third tube profile for
use in a steam boiler;
Figure 10B is an elevational view of a third tube profile for
use in a hot water boiler;
Figure 11 is an elevational view of the combination of tube
profiles used in the front section of a steam boiler;
Figure 12 is an elevational view of the tube profiles used in
the rear portion of a steam boiler;
Figure 13 is a perspective view, partially in cutaway, of the
front portion of a boiler according to the present invention; and
Figure 14 is an enlarged perspective view illustrating the
structural arrangement between the downcomer and fluid flow patterns.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to the drawings in greater detail and by reference
characters thereto, there is illustrated a boiler which is generally
designated by reference numeral 10. Boiler 10 includes a lower header 12
and an upper header or drum 14. Boiler 10 is of a generally overall
rectangular configuration having a front wall 16 and a rear wall 18 with
a burner port 20 being provided in front wall 16. The flow of
combustion gases is illustrated in Figures 1A and 1B by means of arrow
22.
As shown in Figure 1A and as will be discussed in greater
detail hereinbelow, combustion gas flow 22 may initially flow in a first
horizontal direction from the front wall rearwardly, and then reverse
direction as they pass through a so-called turning lane to a convection
zone. A baffle 24 may be utilized to divide the convection zone in two
to allow a further pass before the combustion gases exit through a
combustion gas outlet 26 located proximate rear wall 18.
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In the embodiment illustrated in Figure 1B, baffle 24 is
eliminated while combustion gas outlet 26 is located proximate front
wall 16.
The flow pattern of the combustion gases is partially a
function of the design and arrangement of the bent tube configurations
which will now be referred to,
A first tube profile is shown in Figures 8A and 8B. The
profile of Figure 8A is substantially identical to that of Figure 8B
except that the arrangement shown in Figure 8B is one which would be
suitable for a hot water boiler while the arrangement in Figure 8A would
be suitable for a steam boiler. Similar reference numerals are thus
employed for both embodiments with the embodiment for hot water having
reference numerals in the 100's.
In the illustrated embodiment of Figure 8A, there is provided
a pair of tubes generally designated by reference numeral 30 and which
tubes are in fluid communication with lower header 12 and upper drum or
header 14. At lower header 12, tube 30 has an exit portion 32 connected
approximately halfway up lower header 12. From exit portion 32, there
is an upwardly angled portion 34 which in turn continues on as a
horizontal floor portion 35. Horizontal floor portion 35 is in fluid
communication with a riser 36. At its upper end riser 36 is in fluid
communication with a plurality of U-shaped sections generally designated
by reference numeral 38. At its upper extremity, tube 30 enters upper
drum 14 in its lower right-hand quadrant.
Tubes 30 and 30' are substantial mirror images of each other
about a center plane line 40.
A second tube profile is shown in Figures 9A and 9B and like
the embodiment of Figures 8A and 8B, there are a pair of tubes 43, 43'.
Tube 43 is in fluid communication with lower header 12 and
exits therefrom in its upper right-hand quadrant through exit portion
44. Subsequently, there is provided a horizontal floor portion 45 which
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is in communication with riser 46. In a manner similar to the
previously described embodiment, there are also provided a plurality of
U-shaped portions 47, the uppermost one of which terminates in an
upwardly angled entry portion 48 in fluid communication with the lower
right-hand quadrant of upper drum 14.
A similar arrangement is provided for the embodiment
illustrated in Figure 9B.
The third tube profile is shown in Figures 10A and lOB and
comprises tubes 60 and 60'. In this embodiment, tube 60, in a manner
similar to tube 30, has an exit portion 49 communicating with an
upwardly angled portion 50 which in turn communicates with a horizontal
floor portion 51. A riser 52 extends between horizontal floor portion
51 and a further horizontal floor upper portion 53. Horizontal portion
53 extends inwardly to terminate in a U-shaped portion 54 which has a
leg formed as an upwardly angled portion 55. Subsequently, in an
arrangement similar to the previously described embodiments, there are
provided a plurality of U-shaped portions 56, the uppermost one of which
terminates in a upwardly angled portion 57 in fluid communication with
upper drum 14 in its lower right-hand quadrant.
In a front portion of boiler 10 - i.e. adjacent front wall 16,
the bent tube arrangement is such so as to provide alternating tubes 30
and 43. This arrangement continues for a substantial portion of the
length of a boiler 12 while adjacent rear walls 18, one provides for
alternating tubes of the type shown in Figures 8 and 10 - i.e. tubes 30
and tubes 60 are arranged in an alternating fashion. This creates a
passageway for the gases to pass upwardly into the convection zone
defined by the U-shaped portions of the tubes.
Boiler 10 utilizes a downcomer vertical conduit and downcomer
horizontal conduit arrangement which forms a structural portion of the
boiler and will now be described in greater detail.
Adjacent front wall 16, there is provided a front upper
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horizontal conduit 64 and a front lower horizontal conduit 66. Conduits
64 and 66 are in fluid communication with upper header 14 as indicated
by the arrows. Similarly, downcomer 68 and 70 provide a flow path
between front upper horizontal conduit 64 and front lower horizontal
conduit 66; front lower horizontal conduit is in fluid communication
with lower header 12 as may be best seen in Figures 13 and 14.
Proximate rear wall 18, and in a manner similar to that
described with respect to the arrangement proximate front wall 16, there
is provided a rear upper horizontal conduit 74 and a rear lower
horizontal conduit 76. Rear upper horizontal conduit 74 is in fluid
communication with upper header 14 while rear lower horizontal conduit
76 is
in fluid communication with lower header 12. Downcomers 78 and 80
provide fluid communication between rear upper horizontal conduit 74 and
1_5 rear lower horizontal conduit 76.
The walls may be cooled by means of a plurality of riser tubes
84. Similarly, there may be provided a rear access opening 88 to boiler
12 and a plurality of cooling conduits 90 may be situated thereabout.
Similarly, burner port cooling conduits 94 may be provided in the manner
illustrated in Figure 7B.
Boiler 10 may be enclosed by first side wall 98 having
insulation 100 located adjacent thereto and a second side wall 102
having insulation 104 associated therewith.
The above embodiments provide a number of advantages wherein
the downcomers are adjacent the front and rear walls and are shaped to
contour the furnace and allow for a water cooled front and rear wall.
Apart from the downcomers providing a natural fluid circulation, they
also serve as structural members to strengthen the boiler and provide a
more rugged core. The possibility of having front end or rear water
cooled walls can eliminate refractory maintenance and reduce boiler and
low heat losses.
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In one embodiment, there may be provided soot- blowing pipes
108 which extend longitudinally between the tubes where they meet at the
center line.
It will be understood that the above described embodiment is
for purposes of illustration only and that changes and modifications may
be made thereto without departing from the spirit and scope of the
invention.
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