U.S. patent application number 11/887638 was filed with the patent office on 2009-10-29 for protected carbon steel pipe for fire tube heat exchange devices, particularly boilers.
Invention is credited to Giovanni Jahier.
Application Number | 20090266529 11/887638 |
Document ID | / |
Family ID | 36581553 |
Filed Date | 2009-10-29 |
United States Patent
Application |
20090266529 |
Kind Code |
A1 |
Jahier; Giovanni |
October 29, 2009 |
Protected Carbon Steel Pipe for Fire Tube Heat Exchange Devices,
Particularly Boilers
Abstract
A protected carbon steel pipe for fire tube heat exchange
devices, particularly boilers, comprising internally, at least
along a portion of its length, at least one bonded layer of
corrosion-resistant material.
Inventors: |
Jahier; Giovanni; (Mantova,
IT) |
Correspondence
Address: |
Modiano & Associati
Via Meravigli, 16
Milano
20123
IT
|
Family ID: |
36581553 |
Appl. No.: |
11/887638 |
Filed: |
April 12, 2006 |
PCT Filed: |
April 12, 2006 |
PCT NO: |
PCT/EP2006/003381 |
371 Date: |
October 1, 2007 |
Current U.S.
Class: |
165/180 |
Current CPC
Class: |
F28F 19/06 20130101;
F28F 1/022 20130101; F28F 2215/10 20130101; F28F 1/40 20130101;
F28F 13/06 20130101; F28F 1/003 20130101 |
Class at
Publication: |
165/180 |
International
Class: |
F28F 21/00 20060101
F28F021/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 18, 2005 |
IT |
MN2005A000023 |
Feb 22, 2006 |
IT |
MN2006A000012 |
Claims
1-24. (canceled)
25. A protected carbon steel pipe for fire tube heat exchange
devices, particularly boilers, comprising internally, at least
along a portion of the length of the pipe, at least one bonded
layer of corrosion-resistant material.
26. The pipe according to claim 25, further comprising internally a
single bonded layer of corrosion-resistant material.
27. The pipe according to claim 25, further comprising internally a
double bonded layer of corrosion-resistant material.
28. The pipe according to claim 25, further comprising internally a
closed coaxial sleeve made of corrosion-resistant material, which
is adapted to form an interspace for the flow of the flue
gases.
29. The pipe according to claim 25, further comprising internally a
closed coaxial sleeve made of corrosion-resistant material, which
is adapted to form an interspace for the flow of the flue gases,
the outer surface of the sleeve and the surface of the layer that
faces it being both smooth.
30. The pipe according to claim 25, further comprising internally a
closed coaxial sleeve made of corrosion-resistant material, which
is adapted to form an interspace for the flow of the flue gases,
ribs being provided which protrude monolithically from the sleeve
or the surface of the layer that faces the sleeve and are adapted
to make contact with the surface of the layer that faces it or with
the surface of the sleeve respectively.
31. The pipe according to claim 30, wherein the ribs have a
cross-section shaped like a rounded cusp.
32. The pipe according to claim 30, wherein the ribs have a
rectangular cross-section.
33. The pipe according to claim 30, wherein the ribs have a
triangular cross-section.
34. The pipe according to claim 30, wherein the ribs have a
cross-section which in terms of thickness decreases gradually
toward the central region.
35. The pipe according to claim 30, wherein the ribs have a
rectangular cross-section with an end face.
36. The pipe according to claim 25, comprising internally a closed
coaxial sleeve made of corrosion-resistant material, which is
adapted to form an interspace for the flow of the flue gases, ribs
being provided which protrude alternately from said sleeve and from
the surface of the layer that faces it, the ribs that protrude from
the sleeve being adapted to make contact in the presence of a
reference with said surface.
37. The pipe according to claim 25, further comprising internally a
coaxial sleeve made of corrosion-resistant material, which is
provided with variously shaped ribs which are adapted to make
contact in the presence of a reference with the surface of the
layer that faces the sleeve, said ribs being arranged alternately
with respect to variously shaped ribs which protrude from said
surface.
38. The pipe according to claim 36, wherein the at least one layer
of corrosion-resistant material and the sleeve cover the entire
length of the pipe.
39. The pipe according to claim 36, wherein the at least one layer
of corrosion-resistant material and the sleeve cover partially the
inside of the pipe.
40. The pipe according to claim 36, wherein the at least one layer
of corrosion-resistant material and the sleeve cover different
lengths inside the pipe.
41. The pipe according to claim 25, comprising internally, at least
in one portion of its length, a bonded layer made of
corrosion-resistant material which is provided with protrusions
which protrude toward an axis of said pipe.
42. The pipe according to claim 25, further comprising internally
at least two consecutive modules for conveying the flue gases, each
module being delimited by a closed wall made of corrosion-resistant
material which comprises a portion bonded to the wall of the pipe
and at least one portion which protrudes toward an axis of said
pipe.
43. The pipe according to claim 25, further comprising internally
two flue gas conveyance modules, each module being delimited by a
closed wall made of corrosion-resistant material, which comprises a
portion which is bonded to the wall of the pipe substantially along
half of a circumferential extension thereof, and a straight portion
which protrudes transversely, the straight portions of the wall of
the two modules being in mutual contact.
44. The pipe according to claim 25, further comprising internally a
plurality of flue gas conveyance modules, each module being
delimited by a closed wall made of corrosion-resistant material
which comprises a portion bonded to the wall of the pipe and two
straight portions which protrude from the ends of said portion
bonded to the wall toward an axis of said pipe, the straight
portions of the wall of two consecutive modules being in mutual
contact.
45. The pipe according to claim 25, further comprising internally a
continuous bonded layer of corrosion-resistant material, which is
provided with straight protrusions which protrude toward an axis of
said pipe.
46. The pipe according to claim 25, wherein the corrosion-resistant
material is an aluminum alloy.
47. The pipe according to claim 25, wherein the corrosion-resistant
material is stainless steel.
Description
[0001] The present invention relates to a protected carbon steel
pipe for fire tube heat exchange devices, particularly boilers.
BACKGROUND OF THE INVENTION
[0002] It is known that fire tube heat exchange devices exist which
provide pipes designed to convey flue gases generated by combustion
in appropriate furnaces, such pipes being provided within a vessel
which contains the fluid to be heated; among such devices, boilers
for generating hot water or another heat transfer fluid are
particularly important.
[0003] The pipes comprised within said devices are made of carbon
steel in order to ensure optimum quality of the welded joints
between the pipes and the structures of the devices, which are also
made of carbon steel; however, in the case of devices, such as for
example condensing boilers, in which the water vapor contained in
the flue gases condenses inside the flue gas conveyance pipes,
condensation forms which attacks strongly by corrosion the wall of
the pipes.
[0004] Pipes of the described type are not typical only of boilers,
but can be present also in other devices of industrial thermal
cycles, such as for example condensers, economizers and heat
exchangers.
SUMMARY OF THE INVENTION
[0005] The aim of the present invention is to provide a carbon
steel pipe adapted to convey flue gases which is entirely protected
against the danger of corrosion caused by condensation and further
ensures high efficiency in the transmission of heat from the flue
gases to the fluid, and in particular to the water, to be
heated.
[0006] The proposed aim is achieved by a protected carbon steel
pipe for fire tube heat exchange devices, particularly boilers,
according to the invention, characterized in that it comprises the
features disclosed in the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] Further characteristics and advantages will become better
apparent from the description of some preferred but not exclusive
embodiments of the protected carbon steel pipe for fire tube heat
exchange devices, particularly boilers according to the invention,
illustrated by way of non-limiting example in the accompanying
drawings, wherein:
[0008] FIG. 1 is a longitudinal sectional view of a fire tube
boiler with a pipe according to the present invention;
[0009] FIG. 2 is a partial sectional view, taken along the line
II-II of FIG. 1;
[0010] FIGS. 3 to 25 show the same sectional view according to
variations.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0011] With reference to the FIGS. 1 and 2, the reference numeral 1
generally designates a fire tube boiler with a burner 2, a furnace
3, a flue gas reversal chamber 4a, a vessel 5 which contains the
water to be heated with couplings 5a, 5b respectively for inflow
and outflow, pipes 6 designed to convey the gases generated by
combustion in the furnace which arrive from the reversal chamber 4a
and are sent to the output chamber 4b according to the arrows shown
in FIG. 1.
[0012] The boiler 1 is of the type known as condensing boiler, and
therefore the water vapor contained in the flue gases condenses
therein as they flow within the pipes such as 6; the structure of
said boiler is made of carbon steel.
[0013] An important characteristic of the invention consists in
that the pipe 6 is made of carbon steel and comprises internally,
bonded thereto, a layer 7 made of a corrosion-resistant material,
such as aluminum or stainless steel.
[0014] In this manner, the dual need to be able to weld the pipe to
the carbon steel structure of the boiler and to protect said pipe
against the aggression of the condensation generated in the flue
gases is achieved in an optimum manner.
[0015] As can be seen from FIG. 1, the layer 7 is present along the
entire length of the pipe 6, but it should be clearly noted that
such layer might be provided only in the part of the pipe toward
the outlet of the flue gases.
[0016] An embodiment of the pipe according to the invention is
shown in FIG. 3: the carbon steel pipe 8 comprises, bonded thereto,
a layer 9 made of corrosion-resistant material and accommodates
internally a coaxial sleeve 10, which is closed by at least one
plug 10a, likewise made of corrosion-resistant material.
[0017] An interspace 11 for conveying the flue gases in a reduced
cross-section is thus provided: the consequent increase in speed
effectively helps to increase heat exchange between the flue gases
and the water to be heated.
[0018] A further increased efficiency of said exchange occurs in
the variation of FIG. 4, in which a carbon steel pipe 12 has,
bonded thereto, a layer 13 of corrosion-resistant material, and a
sleeve 14, closed by a plug 14a, has ribs 14b which extend
monolithically from it and which, by entering an interspace 15
through which the flue gases flow, make contact with the layer 13,
transmitting thereto, and ultimately to the water to be heated,
heat by conduction.
[0019] An identical situation occurs in the variations of FIGS. 5,
6, 7, and 8, changing only the shape of the cross-section of the
ribs: while the ribs of the solution of FIG. 4 are shaped so as to
have a cross-section with a rounded cusp, the ribs of the
variations of said figures respectively have a rectangular
cross-section 16, a triangular cross-section 17 in which the
thickness decreases gradually toward the central region 18, and a
rectangular cross-section with an end face 19.
[0020] The variation of FIG. 9 provides, bonded to a carbon steel
pipe 20, a first layer 21 made of corrosion-resistant material, and
a second layer 22, also made of corrosion-resistant material, which
provides ribs 22a adapted to make contact, by entering an
interspace 23 through which the flue gases flow, with a sleeve 24
closed by a plug 24a, thus providing a situation which is similar
to the one described earlier.
[0021] Variations of the cross-sections of the ribs identical to
the ones shown in FIGS. 5, 6, 7, 8 are visible in FIGS. 10, 11, 12,
13: therefore, there is no need to deal with these variations.
[0022] The variations of FIGS. 14 to 18 replicate the constructive
embodiments shown in FIGS. 9 to 13, with the only difference
related to the fact that there is just one layer made of
corrosion-resistant material bonded to the carbon steel pipe: thus,
for example, the variation of FIG. 14 provides, bonded to a carbon
steel pipe 25, only a layer 26 made of corrosion-resistant
material, which is provided with a ribs 26a which make contact with
a sleeve 27.
[0023] FIG. 19 illustrates an embodiment in which a first layer 29,
made of corrosion-resistant material, and a second layer 30, also
made of corrosion-resistant material, are bonded to a carbon steel
pipe 28; ribs 30a protrude from said second layer and are
alternated with ribs 31 a which protrude from a sleeve 31, leaving
spaces 32 between said ribs for the flow of the flue gases: ribs
31a extend until they make contact with the layer 30 in the
presence of references 31b which ensure correct positioning.
[0024] A variation of the embodiment of FIG. 19 is shown in FIG.
20: the only difference is the absence of the layer 29 bonded to a
carbon steel pipe 33, and therefore only a layer 34 made of
corrosion-resistant material and provided with the ribs as
described above, is present.
[0025] The variation shown in FIG. 21 is now described: it
comprises, bonded to a carbon steel pipe 35, a layer 36 made of
corrosion-resistant material, which is provided with variously
shaped ribs 36a arranged alternately with respect to variously
shaped ribs 37a which protrude from a sleeve 37 and are adapted to
make contact in the presence of references 37b with the wall of the
layer 36.
[0026] Another variation is described with reference to FIG. 22, in
which the reference numeral 38 designates a carbon steel pipe,
which comprises internally two flue gas conveyance modules,
designated generally by the reference numerals 39 and 40
respectively, which are delimited by a closed wall made of
corrosion-resistant material.
[0027] The wall of the module 39 comprises a portion 41, which is
bonded to the wall of the pipe 38 substantially along half of the
circumferential extension thereof, and a straight portion 42, which
extends transversely, and likewise the wall of the module 40
comprises a portion 43 bonded to the wall of the pipe 38 and a
straight portion 44; the straight portions 42 and 44 are in mutual
contact.
[0028] The described configuration allows to obtain the dual result
of protecting the wall of the pipe 38 against contact with the flue
gases, and this is done by the portions 41 and 43 of the walls of
the modules, and of providing an intense transmission of heat from
the flue gases to the water contained in the boiler which strikes
the outer surface of the pipe 38, determined by the presence of the
portions 42 and 44 of said walls which make contact with the flue
gases at the region where said flue gases have a particularly high
temperature.
[0029] FIG. 23 illustrates another variation of the invention,
which provides, inside the pipe 38, six flue gas conveyance modules
which are substantially shaped like wedges and are designated
respectively by the reference numerals 45, 46, 47, 48, 49, 50.
[0030] The walls of the module, which are made of
corrosion-resistant material, are identical and comprise an
arc-like portion, 45a for the module 45, bonded to the wall of the
pipe 38, and two straight portions 45b, 45c for said module, which
protrude from the ends of said arc-like portion toward the axis of
said pipe; the straight portions of the individual modules are in
mutual contact.
[0031] Of course, this embodiment, too, ensures the functional
characteristics stated with reference to the embodiment shown in
FIG. 22.
[0032] As regards the variation of FIG. 24, it differs from the
embodiment of FIG. 23 only in that inside the pipe 38 there are
twelve flue gas conveyance modules 51 instead of the six modules
provided in the embodiment of FIG. 23.
[0033] The variation shown in FIG. 25 provides for the presence,
inside the pipe 38, of a continuous layer 52, provided with
protrusions such as 53 which protrude toward the axis of the pipe
and thus provide, as in the previously described variations,
optimum conditions both as regards the protection of the pipe 38
against corrosion and for high efficiency in heat transfer from the
flue gases contained in the pipe 38 to the water to be heated.
[0034] The described invention is susceptible of numerous other
modifications and variations, all of which are within the scope of
the appended claims: thus, for example, it is important to stress
the fact that the various means for protecting the carbon steel
pipe made of corrosion-resistant material may cover different
lengths within the described pipes.
[0035] The disclosures in Italian Patent Applications No.
MN2005A000023 and No. MN2006A000012 from which this application
claims priority are incorporated herein by reference.
* * * * *