BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic sectional side view of a steam generator including a heat exchanger embodying the present invention;
FIG. 2 is a fragmented, sectional side view of the heat exchanger, and its tube banks and support members;
FIG. 3 is a fragmented, perspective view of the heat exchanger tube banks and support members;
FIG. 4 is a fragmented, enlarged sectional view of the vertical support members and the lateral cross bars taken along line 4-4 of FIG. 3;
FIG. 5 is a fragmented, enlarged side view of the vertical support members and the lateral cross bars taken along line 5-5 of FIG. 4;
FIG. 6 is a fragmented, enlarged sectional view of the diagonal support members and the lateral compression supports taken along line 6-6 of FIG. 3; and
FIG. 7 is a fragmented, enlarged side view of the diagonal support members and the lateral compression supports taken along line 7-7 of FIG. 6.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Reference will hereinafter be made to the accompanying drawings wherein like reference numerals throughout the various figures denote like elements.
Referring to FIG. 1, there is shown a steam generator 10 including water cooled tubular walls 12 that define a furnace chamber or combustion space 14 to which a fuel and air mixture is supplied by burners as schematically shown at 16. After combustion has been completed in the furnace chamber 14, the hot gases flow upwardly and around the furnace chamber nose portion 18, and across through the horizontal section 22 of the convection passageway 23, and thence downwardly through the vertical section 24 of the convection passageway 23 which is defined by walls 25 and includes a heat exchanger such as the primary superheater 26. Usually, the gases leaving the vertical section 24 of the convection passageway 23 flow through an air heater, not shown, and thence through a gas clean-up system, not shown, and are thereafter discharged through a stack, not shown.
It will be understood that in accordance with well known practice, the heat exchanger 26 includes banked rows 27 of spaced serpentine tubes 28, as shown in FIG. 3, extending across the width of the vertical section 24 of the convection passageway 23, and arranged for fluid flow therethrough and in indirect heat exchange with the combustion gases flowing through the vertical section or passageway 24.
Referring to FIGS. 2 and 3, there are shown fragmented sectional side and perspective views, respectively, of a heat exchanger 26 including a plurality of serpentine tubes 28 disposed in side-by-side parallel relation to one another, as shown in FIG. 3, and across the gas stream which is flowing through the vertical section 24 of the convection passageway 23, as shown in FIGS. 1 and 2, and with each serpentine tube 28 having elongate sloped-tube segments 30 and return-bend tube segments 32 forming the rows 27 of tube banks 34. In accordance with the invention, the elongated tube segments 30 of the serpentine tubes 28 extend at an angle downwardly from the horizontal to cause fluid to be drained from the serpentine tubes 28 when the steam generator 10, shown in FIG. 1, is shutdown.
The serpentine tubes 28 of heat exchanger 26 are supported by vertically extending structural frameworks 39 and diagonally extending structural frameworks 41. The heat exchanger 26 is itself supported by the walls 25, shown in FIGS. 1 and 2, by way of the first support lugs 35 which are rigidly connected, preferably by welding, to the lower end of the outermost return-bend tube segment 32 of each tube bank 34 and slidably engaged with the second support lugs 37, the latter being rigidly connected, preferably by welding, to the walls 25. The diagonally extending structural frameworks 41 are located closest to the return-bend segments 32 and transmit the heat exchanger 26 support loads to the first support lugs 35 which, in turn, transmit the support loads to the second support lugs 37 and thence onto the walls 25 of vertical passageway 24.
The vertically extending structural framework 39 includes first support members 36 which are generally in the form of vertically extending bars or plates that are paired to contiguously straddle the sloped-tube segments 30, and second support members 38, shown in FIG. 3, which are generally in the form of laterally extending cross bars or plates which run between the straddled sloped-tube segments 30.
The vertically extending first support members 36 are rigidly attached to or connected with the laterally extending second support members 38, preferably by welding, to insure that the latter remain tightly drawn against the straddled sloped-tube segments 30, while preserving the spacing between the sloped-tube segments 30 and preventing direct contact between adjoining tube surfaces. In accordance with the invention, the rigidly interconnected first and second support members 36 and 38, respectively, are not welded or otherwise attached to the serpentine tubes 28, thereby creating a structural framework 39 which provides a tube supporting fit that is loose enough to permit relative thermal expansion and contraction of the serpentine tubes 28 and the framework 39, the latter being comprised of the first and second support members 36 and 38, respectively.
The diagonally extending structural framework 41 includes first support members 42 which are generally in the form of diagonally extending bars or plates that are paired to contiguously straddle the sloped-tube segments 30, and second support members or compression supports 44, shown in FIG. 3, which are generally in the form of laterally extending blocks that run between the straddled sloped-tube segments 30, and are contoured to engage the adjacent surfaces of the sloped-tube segments 30.
The compression supports 44 are rigidly secured to the paired diagonally extending first support members 42, preferably by welding, to insure that the latter remain tightly drawn against the straddled sloped-tube segments 30, while preserving the spacing between the sloped-tube segments 30, and preventing direct contact between adjoining tube surfaces, and also transmitting the heat exchanger 26 support loads from the first support lugs 35 to the second support lugs 37 and hence to the walls 25 which form the vertical section 24 of the convection passageway 23. In accordance with the invention, the rigidly interconnected first and second support members or compression supports 42 and 44, respectively, are not welded or otherwise attached to the serpentine tubes 28, thereby creating a structural framework 41 which provides a heat exchanger and tube supporting fit that is loose enough to permit relative thermal expansion and contraction of the serpentine tubes 28 and the framework 41, the latter being comprised of the first and second support members 42 and 44.
Referring to FIGS. 4 and 5 there are shown fragmented, enlarged sectional and side views of the vertically extending first support members 36 and the laterally extending second support members or cross bars 38. The paired first support members 36 straddle the sloped-tube segments 30 of the serpentine tubes 28. The first support members 36 are drawn tightly against the sloped-tube segments 30 and are rigidly maintained in that position by the second support members or cross bars 38, which are rigidly attached to the first support members 36 by welds 40. The vertically extending structural framework 39 formed by the first support members 36 and the second support members 38 preserves the spacing between the sloped-tube segments 30 and prevents direct contact between adjoining tube surfaces, but is not attached to the straddled sloped-tube segments 30 and is loose enough to allow the serpentine tubes 28 and the structural framework 39 to move freely in response to thermal expansion and contraction.
Referring to FIGS. 6 and 7 there are shown fragmented, enlarged sectional and side views of the diagonally extending first support members 42 and the laterally extending second support members or compression supports 44. The first support members 42 are drawn tightly against the sloped-tube segments 30 and are maintained in that position by the second support members or compression supports 44, which are rigidly attached to the first support members 42 by welds 43. The second support members or compression supports 44 are formed as a solid block of concavo-concave cross-sectional configuration so as to have the concave recesses 45 engage the contiguous portion of the adjacent sloped-tube segments 30, as shown in FIG. 7, and thereby support the serpentine tube 28 off the first support members 42, while maintaining the spacing between adjacent sloped-tube segments 30. The diagonally extending framework 41 formed by the first support members 42 and the second support members or compression supports 44 maintains the spacing between the sloped-tube segments 30 and prevents direct contact between adjacent tube surfaces, while also supporting the serpentine tubes 28 off the first support members 42, but is not attached to the straddled sloped-tube segments 30, and is loose enough to allow the serpentine tubes 28 and the structural framework 41 to move freely in response to thermal expansion and contraction.
Although the present invention has been described above with reference to particular means, materials, and embodiments, it is to be understood that this invention may be varied in many ways without departing from the spirit and scope thereof, and therefore is not limited to these disclosed particulars but extends instead to all equivalents within the scope of the following claims.
Patent Application
20080022949
