Protected Carbon Steel Pipe for Fire Tube Heat Exchange Devices, Particularly Boilers
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.
The present invention relates to a protected carbon steel pipe for fire tube heat exchange devices, particularly boilers.
BACKGROUND OF THE INVENTIONIt 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.
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.
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 INVENTIONThe 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.
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.
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:
With reference to the
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.
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.
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.
As can be seen from
An embodiment of the pipe according to the invention is shown in
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.
A further increased efficiency of said exchange occurs in the variation of
An identical situation occurs in the variations of
The variation of
Variations of the cross-sections of the ribs identical to the ones shown in
The variations of
A variation of the embodiment of
The variation shown in
Another variation is described with reference to
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.
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.
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.
Of course, this embodiment, too, ensures the functional characteristics stated with reference to the embodiment shown in
As regards the variation of
The variation shown in
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.
The disclosures in Italian Patent Applications No. MN2005A000023 and No. MN2006A000012 from which this application claims priority are incorporated herein by reference.
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.
Type: Application
Filed: Apr 12, 2006
Publication Date: Oct 29, 2009
Inventor: Giovanni Jahier (Mantova)
Application Number: 11/887,638
International Classification: F28F 21/00 (20060101);