WATER TUBE BOILER

CHAUDIERE AQUATUBULAIRE

English Abstract

ABSTRACT
In a water tube boiler comprising a housing
enclosing tubes bent to form vertical chambers
successively traversed by rising hot combustion gases,
the tubes being connected at the bottom to a cold water
manifold and at the top to a stearn manifold, the
manifolds project beyond the housing with a downcomer
outside the housing connecting the top of the lower
manifold and the lowest part of the upper manifold,
thereby permitting the boiler to operate with a shallow
level of water in the upper manifold, speeding up
circulation of water and its heating, and permitting
substantially dry steam to be discharged from the upper
manifold. The chambers may include baffles which are
angled so that the hot gas hits them at an angle less
than 90° so as to be deflected thereby in the direction
of its advance, thereby avoiding hot spots.
Advantageously successive chambers from bottom to top
are reduced in volume to make up for the reduction in
volume as the hot gas cools, thereby keeping the gas
velocity high and maintaining turbulence which helps
heat exchange. For efficient fuel utilization,
notwithstanding fluctuations in demand, the operator
can monitor the oxygen content of the exiting
combustion gas and adjust the baffling to maintain it
substantially constant.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR
PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In a boiler comprising a housing having a
top provided with a gas outlet, bottom, left and right
sides and a front and back, the housing containing an
upper manifold and a lower manifold substantially
parallel to the top, bottom and side walls, two sets of
tubes, each set comprising a plurality of tubes, one
set joining the upper manifold to the lower manifold on
the left and the other set joining the upper manifold
to the lower manifold on the right, the tubes of each
set rising from the lower manifold upwardly along their
respective side wall, crossing the housing to the
opposite side wall, rising adjacent the opposite side
wall, re-crossing the housing to their respective side
wall, rising therealong and eventually joining the
upper manifold, the horizontal runs of the tubes of one
set being vertically offset relative to the horizontal
runs of the tubes of the other set so as to form a
plurality of superposed chambers, individual tubes of
the sets being differently bent so as to form access
openings from each chamber to the chambers above and
below, the openings from chamber to chamber being
offset so as to require a gas flowing through said
chambers to traverse one chamber from front to back and
the next chamber from back to front, means for
introducing liquid into one of the manifolds and for
withdrawing the liquid from the other manifold, and
means for introducing a hot gas into the lowermost of
the superposed chambers, the hot gas rising
successively through the chambers which it successively
and alternately traverses from front to back and then
from back to front until it exits from the uppermost
chamber through the gas outlet in the top, liquid
flowing through the manifolds and tubes being heated by
the hot gas, at least one baffle within. at least one of
the chambers extending from top to bottom and from one
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of the sides toward but terminating short of the other,
whereby hot gas traversing that chamber from front to
back is additionally forced to flow laterally to get
around said baffle, the improvement which comprises
having at least one upper and at least one lower
manifold project from the inside of the housing to the
outside, and a downcomer outside the housing connecting
the top of the lower manifold and the lowest part of
the upper manifold, thereby permitting the boiler to
operate with a shallow level of water in the upper
manifold, speeding up circulation of water and its
heating, and permitting substantially dry steam to be
discharged from the upper manifold.
2. A boiler according to claim 1, wherein
all the tubes join the upper manifold at or below the
upper manifold's horizontal center line.
3. A boiler according to claim 2, wherein
each tube in going from lower to upper manifold has
lengths which rise or are horizontal but has no lengths
which go downwardly, thereby avoiding entrapment of
gas.
4. A boiler according to claim 1, wherein
the boiler has five, seven or nine chambers.
5. A boiler according to claim 1, wherein
the baffle is angled within its chamber so that the hot
gas hits it at an angle less than 90° so as to be
deflected thereby in the direction of its advance,
thereby avoiding hot spots.
6. A boiler according to claim 1, wherein
successive chambers from bottom to top are reduced in
volume to make up for the reduction in volume as the
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hot gas cools, thereby keeping the gas velocity high
and maintaining turbulence which helps heat exchange.
7. A boiler according to claim 6, including
a plurality of baffles in a plurality of chambers, the
baffles being angled within their chambers so that the
hot gas hits them at an angle less than 90° so as to be
deflected thereby in the direction of its advance,
thereby avoiding hot spots.
8. In a boiler comprising a housing having a
top provided with a gas outlet, bottom, left and right
sides and a front and back, the housing containing an
upper manifold and a lower manifold substantially
parallel to the top, bottom and side walls, two sets of
tubes, each set comprising a plurality of tubes, one
set joining the upper manifold to the lower manifold on
the left and the other set joining the upper manifold
to the lower manifold on the right, the tubes of each
set rising from the lower manifold upwardly along their
respective side wall, crossing the housing to the
opposite side wall, rising adjacent the opposite side
wall, re-crossing the housing to their respective side
wall, rising therealong and eventually joining the
upper manifold, the horizontal runs of the tubes of one
set being vertically offset relative to the horizontal
runs of the tubes of the other set so as to form a
plurality of superposed chambers, individual tubes of
the sets being differently bent so as to form access
openings from each chamber to the chambers above and
below, the openings from chamber to chamber being
offset so as to require a gas flowing through said
chambers to traverse one chamber from front to back and
the next chamber from back to front, means for
introducing liquid into one of the manifolds and for
withdrawing the liquid from the other manifold, and
means for introducing a hot gas into the lowermost of
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the superposed chambers, the hot has rising
successively through the chambers which it successively
and alternately traverses from front to back and then
from back to front until it exits from tile uppermost
chamber through the gas outlet in the top, liquid
flowing through the manifolds and tubes being heated by
the hot gas, at least one baffle within at least one of
the chambers extending from top to bottom and from one
of the sides toward but terminating short of the other,
whereby hot gas traversing that chamber from front to
back is additionally forced to flow laterally to get
around said baffle, the improvement which comprises
angling the baffle within its chamber so that the hot
gas hits it at an angle less than 90° so as to be
deflected thereby in the direction of its advance,
thereby avoiding hot spots.
9. A boiler according to claim 7, wherein
successive chambers from bottom to top are reduced in
volume to make up for the reduction in volume as the
hot gas cools, thereby keeping the gas velocity high
and maintaining turbulence which helps heat exchange.
10. A boiler according to claim 9, including
a plurality of baffles in a plurality of chambers, the
baffles being angled within their chambers so that the
hot gas hits them at an angle less than 90° so as to be
deflected thereby in the direction of its advance,
thereby avoiding hot spots.
11. In a boiler comprising a housing having a
top provided with a gas outlet, bottom, left and right
sides and a front and back, the housing containing an
upper-manifold and a lower manifold substantially
parallel to the top, bottom and side walls, two sets of
tubes, each set comprising a plurality of tubes, one
set joining the upper manifold to the lower manifold on
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the left and the other set joining the upper manifold
to the lower manifold on the right, the tubes of each
set rising from the lower manifold upwardly along their
respective side wall, crossing the housing to the
opposite side wall, rising adjacent the opposite side
wall, re-crossing the housing to their respective side
wall, rising therealong and eventually joining the
upper manifold, the horizontal runs of the tubes of one
set being vertically offset relative to the horizontal
runs of the tubes of the other set so as to form a
plurality of superposed chambers, individual tubes of
the sets being differently bent so as to form access
openings from each chamber to the chambers above and
below, the openings from chamber to chamber being
offset so as to require a gas flowing through said
chambers to traverse one chamber from front to back and
the next chamber from back to front, means for
introducing liquid into one of the manifolds and for
withdrawing the liquid from the other manifold, and
means for introducing a hot gas into the lowermost of
the superposed chambers, the hot gas rising
successively through the chambers which it successively
and alternately traverses from front to back and then
from back to front until it exits from the uppermost
chamber through the gas outlet in the top, liquid
flowing through the manifolds and tubes being heated by
the hot gas, at least one baffle within at least one of
the chambers extending from top to bottom and from one
of the sides toward but terminating short of the other,
whereby hot gas traversing that chamber from front to
back is additionally forced to flow laterally to get
around said baffle, the improvement wherein successive
chambers from bottom to top are reduced in volume to
make up for the reduction in volume as the hot gas
cools, thereby keeping the gas velocity high and
maintaining turbulence which helps heat exchange.
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12. A process for maintaining efficient
utilization of fuel while fluctuating the feed of fuel
to a burner supplying hot combustion gas to the
lowermost chamber of a boiler comprising a housing
having a top provided with a gas outlet, bottom, left
and right sides and a front and hack, the housing
containing an upper manifold and a lower manifold
substantially parallel to the top, bottom and side
walls two sets of tubes, each set comprising a
plurality of tubes, one set joining the upper manifold
to the lower manifold on the left and the other set
joining the upper manifold to the lower manifold on the
right, the tubes of each set rising from the lower
manifold upwardly along their respective side wall,
crossing the housing to the opposite side wall, rising
adjacent the opposite side wall, re-crossing the
housing to their respective side wall, rising
therealong and eventually joining the upper manifold,
the horizontal runs of the tubes of one set being
vertically offset relative to the horizontal runs of
the tubes of the other set so as to form a plurality of
superposed chambers, individual tubes of the sets being
differently bent so as to form access openings from
each chamber to the chambers above and below, the
openings from chamber to chamber being offset so as to
require a gas flowing through said chambers to traverse
one chamber from front to back and the next chamber
from back to front, means for introducing liquid into
one of the manifolds and for withdrawing the liquid
from the other manifolds and means for introducing a
hot gas into the lowermost of the superposed chambers,
the hot gas rising successively through the chambers
which it successively and alternately traverses from
front to back and then from back to front until it
exits from the uppermost chamber through the gas outlet
in the top, liquid flowing through the manifolds and
tubes being heated by the hot gas, at least one baffle
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within at least one of the chambers extending from top
to bottom and from one of the sides toward but
terminating short of the other, whereby hot gas
traversing that chamber from front to hack is
additionally forced to flow laterally to get around
said baffle, comprising monitoring the oxygen content
of the hot gas exiting the boiler, and adjusting the
position of the baffle substantially to restore the
oxygen content to a predetermined value.
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Description

S713
q~his application relates -to improvements in
the construction and operation of a water tube boiler
comprlsing a housing containing upper ancl lower left
and right water manifolds. Tubes connect the left
manifolds and o-ther tubes the right rnani.folds. The
tubes are bent toward one another to form a plurality
of superposed chambers through which combustion gases
must successively flow, from front to back in one
chamber and from back to front within the ne~t.
In U.S. Patent ~,355,602 there is d~scribed a
simple boiler of the abovementionecl type which is
relatively simple and inexpensive to manufacture and
operate. That boiler comprises a housing having a top
provided with a yas outlet, bottom, left and right
sides and a front and back, the housing containing an
upper manifold and a lower manifold substantially
parallel to the top, bottom and side wall.s, two sets of
tubes, each set comprising a plurality of tubes, one
set joining the upper manifold to the lower manifold on
the left and the other set joining the upper manifold
to the lower manifold on the right, the tubes of each
set rising from the lower manifold upwardly along their
respective side wall, crossing the housing -to the
opposite side wall, rising adjacent the opposite sid`e
wall, re-crossing the housing to their respective side
wall, rising thereal.ong and eventually joining the
upper manifold, the horizontal runs of the tubes of one
set being vertically offset relative to the horizontal
runs of the tubes of the other set so as to form a
plurality oE superposed chambers, individual tubes of
the sets being differently bent so as to form access
openings from each chamber to the chambers above and
below, the openings from chamber to chamber being

57~;~
offset so as -to require a yas flowing th:rouyh said
chambers to traverse one chamber ~rom front to back and
-the next chamber from back to :Eront, means .Eor
in-troduclng li~id in-to one o:E the mani.:Eolds and for
withdrawing the liqu.id from the other manifolcl, and
means for introducing a hot gas into the lowermost of
the superposed chambers, the hot gas risiny
successively through the chambers which it successively
and alternately traverses from front to back and then
from back to front until it exits from the uppermost
chamber through the gas out:Let in the top, liquid
flowing through the manifolds ancl tubes being heated by
the hot gas, at least one baffle within at least one of
the chambers extending from top to bottom and from one
of the sides toward but terminating shor-t of the other,
whereby hot gas traversing that chamber from front to
back is additionally forced to flow laterally to get
around said baffle.
It is an object of the present invention to
improve the efficiency of operation of such a boiler by
simple structural modifications and by simple
procedural demands.
These and other objects and advantages are
realized in accordance with the present invention
pursuant to which at least one upper and at least one
lower manifold project from the inside of the housin~
to the outside. A downcomer outside the housing
connects the top o~ the lower manifold and the lowest
part of the upper manifold, thereby permitting the
boiler to operate within a shallow level of water in
the upper manifold, speeding up circulation of water
and its heating, and permitting substantially dry steam
to be discharged from the upper manifold.
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~2~5~ 3
... ..
In accordance with another aspect o~ ~he
invention the baf~le (or baffles) is angled within its
chamber so that the hot gas hits it at an angle less
than 90 so as to b~ defl~cted ~hereby in the direction
of its advance, thereby avoiding hot ~pots.
j' :
In accordance with yet another aspect o the
invention successive chambers of the boiler are reduced
in volume from bottom to top to make up for the
reduction in volume as the hot gas cools, thereby
keeping the gas velocity high and maintaining
turbulence which helps heat exchange.
Finally, to maintain efficient fuel
u~ilization while fluctuating the reed of fuel, the
operator can monitor the oxygen content of the exiting
combustion gas and adjust the baffling to maintain it
substantially consta~t.
.
The invention will be further described with
reference to the accompanying drawings, wherein:
Fig. 1 is a perspective view of a boiler in
accordance with the invention;
Fig. 2 is a front ~iew of a modified boiler
; ~ without baffles and downcomer;
Fig. 3 is a side view of the boiler of Fig. 2
showing the connection of tubes and downcomer with the
manifolds;
; Fig. 4 is a plan view of the preferred
arrangement of ba~1es in a cha~ber of the boiler o~ Fig. l; and
Fig. 5 is a perspective view of one baf~le of
Fig. 4.
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' ,~j~ v" ~

~s~
Referring now more particularly to th~ drawing~,
in Fig. 1 there i5 shown a housing 10 having a top wall
12, a bottom wall 14, a left side wall 16, a right side
wall 18, a fron~ wall 20 and a rear wall 22. A pair of
lower manifolds 24 and upper manifolds 26 project through
the ~ront and rear walls 20 and 22. Means are provided
to introduce cold water into the lower manifolds at 28
and to remove steam from the upper manifolds at 30,
outside the housing. The ends of the lower manifol~s
24 are sealed at 32 and the ends of the upper manifolds
are sealed at 34.
A downcomer outside the housing, as 68 and 70 in
Fig. 3, co~nects ~he lowest part of the upper manifold 26 with
the top of the lower ma~i~old 24 so that water in the upper
manifold can rapidly run down for reheating, speeding
up the circulation. This also permits the upper
mani~old to operate with a shallow level of water which
also speeds up production o~ steam and which permits
substantially dry steam ~o be discharged ~rom the upper
mani~old 26.
A plurality o~ tubes 36, illustratively
twenty-three, extend ~rom the left upper manifold 26 to
the left lower manifold 24 and a similar number o~
tubes 38 extend from the ~ight upper manifold 26 to the:
right lower manifold 24. Except for the ~irst 36a and
last 36c ew tubes in each set, for a rcason to be
described later, the balance o the tubes 36b are all
similarly bent as are the tubes 38.
Each tube has a vertical component and tubes
38a and 38b have two hori~ontal components, i.e. one
run to the let side of the boiler, or actually to the
tubes 36, and ~hen a return run. The bends in tubes 38
are not identical to those of tubes 36 but ra~her
complementary so that together they form a series of
vertically superposed chambers 40a, 40b, 40c, 40d and
40e, decreasinq in volume from bottom to top to make up

571~
for reduction in vo1ume ~, the hot gas cools, thereby
keeping the gas velocit~ hicJh and maintaining
turbulence which helps hea-t exchange.
Advantageously, the boiler has five, seven or
nine chambers. Combustion gases in chamber 40a rise
-through SUC}l space and enter chamber 40b traversing it
horizontally from bac]c to front. The tube bends
similarly cause the gases to traverse successive
chambers until they reach -the topmost chamber 40e where
they exit -through an opening in the top 12.
For improved heat exchange, in addition to
the tortuous gas flow so far defined, a more complex
flow is possible. Thus rectangular baffles 46 having
the shape shown in Fig. 5 may be provided, extending
from adjacent one side wall toward but short of the
other. They are just high enough to span a chamber
being held in position by their fit between the troughs
formed by adjacent tubes. They are inserted by simple
sliding and may be removed, or slid more or less into
their chambers, ei-ther manually or automatically (not
shown), as desired.
If more than one baffle 46 is presen-t ln a
given chamber they must alternately extend from
opposite sides. Thus while the combustion gas is
moving from rear to front in chamber 40b the gas stream
must move from side to side to get around the baffles.
As shown in Figs~ 4 and 5 the baffles have
front and rear elements wh:ich are high and low enough
to lodge in the nips between adjacent tubes. In
between there is a lower section which is just high
enough to clear the minimum vertical space of the
chamber. This section is arranged at an angle less
than 90C, e.g. about 45 so the gas will be deflected
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~ S~7~3
off it in a direction which will help advance the gas,
thereby avoiding hot spots.
In the embodiment o~ Fig. 2 there is a single
lower manifold 50 in place of the dual lower mani~olds
28 of Fig. 1. Similarly there is a single upper manifold
52. The tubes connect with these manifolds 50 and 52 at,
72 and 74, respectively (Fig. 3).
In Figs. 1, 2 and 3 it can be seen that the
connections between the, tubes and upper manifo}d are
not in a straight line but rather are staggered.
However, all the tubes join the upper mani~old at or
below the upper manifold's horizontal center line and
each tube in going from lower to upper manifold has
lengths which rise or are horizontal but has no lengths
which go downwardly`, thereby avoiding entrapment of
'gas.
The ba~fles can serve a further purpose, viz.
maintaining e~ficient utilization o~ ~uel
notwithstanding fluctuating ~uel ~eed rates as a
consequence o~ ctuation in steam demand.
Specifically, one monitors the oxygen content of the
hot gas exiting the boiler which otherwise will change
as ~eed and demand vary, EIowever, the position of the
baffle or ~a~les is adjusted to maintain this oxygen
content cubstantially constant, e.g. as demand goes
down the oxygen content will go up, so the ba~fle
positions will be adjusted to give more baf~ling and
thereby restore the oxygen level to the predetemined
value.
Xt will be understood tha the speci~ication
and examples are illustra~ive but no~ limitative o~ the
present invention and that other embodiments within the
spirit and scope of the invention will ~uggest
themselves to those skilled in ~he art.
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Representative Drawing