Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F22—STEAM GENERATION
  • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
  • F22B37/00—Component parts or details of steam boilers
  • F22B37/02—Component parts or details of steam boilers applicable to more than one kind or type of steam boiler
  • F22B37/22—Drums; Headers; Accessories therefor
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
  • F28F9/00—Casings; Header boxes; Auxiliary supports for elements; Auxiliary members within casings
  • F28F9/02—Header boxes; End plates
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
  • F16L41/00—Branching pipes; Joining pipes to walls
  • F16L41/08—Joining pipes to walls or pipes, the joined pipe axis being perpendicular to the plane of the wall or to the axis of another pipe
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
  • F28F9/00—Casings; Header boxes; Auxiliary supports for elements; Auxiliary members within casings
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
  • F28F9/00—Casings; Header boxes; Auxiliary supports for elements; Auxiliary members within casings
  • F28F9/02—Header boxes; End plates
  • F28F9/0243—Header boxes having a circular cross-section
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
  • F28F9/00—Casings; Header boxes; Auxiliary supports for elements; Auxiliary members within casings
  • F28F9/02—Header boxes; End plates
  • F28F9/026—Header boxes; End plates with static flow control means, e.g. with means for uniformly distributing heat exchange media into conduits
  • F28F9/0263—Header boxes; End plates with static flow control means, e.g. with means for uniformly distributing heat exchange media into conduits by varying the geometry or cross-section of header box

Definitions

• This disclosure is related to shape optimized headers and to methods of manufacture thereof.
• headers to collect fluids (e.g., steam and/or other vapors).
• fluids e.g., steam and/or other vapors.
• headers and the associated distribution hardware are always possessed of circular cross-sectional geometries with uniform wall thicknesses. These geometrical attributes are selected because they can easily be manufactured from available pipe, or by rolling and seam welding plates, or by centrifugal casting. Ease of manufacturing dictates the shapes of the header geometry as well as the wall thicknesses.
• the Figure 1 depicts a front view and a side view of a current commercially available header 100 (also referred to herein as a "comparative header").
• the header 100 comprises a shell 102 of a uniform circular cross-sectional internal diameter "d” and a uniform wall thickness "t" that is in communication with an array of tubes 104 that enter the header along its length.
• the shell 102 is operative to collect a fluid that is discharged into the shell via the array of tubes 104.
• the shell 102 comprises a first end 106 and a second end 108 that is opposite to the first end 106.
• the first end 106 is sealed to the outside, while the second end 108 is in communication with an outlet port (not shown) that permits the evacuation of the fluid that is collected in the header 100 to the outside.
• the steam pressure and/or the fluid flow rate into the header 100 is lowest in the array of tubes 104 that are closest to the first end 106 while it is highest in the array of tubes 104 that are closest to the opposite end.
• the internal diameter "d" of the shell 102 is determined by considering the pressure drop within the shell 102. This is done to ensure that the array of tubes 104 are controlling the resistance in the system.
• the diameter d of the shell 102 is also calculated in such a manner as to limit frictional losses in the header itself. This internal diameter d then defines the bore of the pipe used to fabricate the shell 102.
• the header design shown in the Figure 1 is larger than it needs to be, other than at the outlet plane, and consequently uses a larger amount of material than needed for an efficient design. This increases material costs and results in headers that are expensive and occupy more space in the plant than needed.
• headers and associated distribution systems that can operate under existing conditions in a plant for time periods that are as long or longer than the currently existing header designs.
• a shape optimized header comprising a shell that is operative for collecting a fluid; wherein an internal diameter and/or a wall thickness of the shell vary with a change in pressure and/or a change in a fluid flow rate in the shell; and tubes; wherein the tubes are in communication with the shell and are operative to transfer fluid into the shell.
• a method comprising fixedly attaching tubes to a shell; wherein the shell is operative for collecting a fluid; wherein an internal diameter and/or a wall thickness of the shell vary with a change in pressure and/or a change in a fluid flow rate in the shell; and wherein the tubes are in communication with the shell and are operative to transfer fluid into the shell.
• Figure 1 depicts a front view and a side view of a current commercially available header 100 (also referred to herein as a "comparative header");
• Figure 2 depicts a shape optimized version of the comparative header of the Figure 1 in accordance with the present invention
• Figure 4 is a front view of an exemplary embodiment that depicts the header 200 of the Figure 2, with the exception that the cross-sectional area of the shell is increased from the first end 206 to the second end 208 in a step-wise manner;
• Figure 5A shows a comparative configuration (prior art) for a header 100 having a plurality of outlets
• Figure 5B shows a shaped optimized configuration for the same header of the Figure 5A having a plurality of outlets in accordance with the present invention
• Figure 6 A shows a comparative configuration (prior art) for a header 100 having the central tee
• Figure 6B shows a shaped optimized configuration for the same header 200 having a single outlet in accordance with the present invention
• Figure 7 A depicts a cross section of a comparative header wall 100 at the point where the tube 104 contacts the wall of the shell 102 of the Figure 6 A;
• Figure 7B depicts a cross sectional view of the wall of a shape optimized header 200 of the Figure 6B.
• first, second, third etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present invention.
• relative terms such as “lower” or “bottom” and “upper” or “top,” may be used herein to describe one element's relationship to another element as illustrated in the Figures. It will be understood that relative terms are intended to encompass different orientations of the device in addition to the orientation depicted in the Figures. For example, if the device in one of the figures is turned over, elements described as being on the “lower” side of other elements would then be oriented on “upper” sides of the other elements. The exemplary term “lower,” can therefore, encompasses both an orientation of “lower” and “upper,” depending on the particular orientation of the figure.
• Exemplary embodiments are described herein with reference to cross section illustrations that are schematic illustrations of idealized embodiments. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, embodiments described herein should not be construed as limited to the particular shapes of regions as illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. For example, a region illustrated or described as flat may, typically, have rough and/or nonlinear features.
• shape optimized headers shaped optimized headers and associated conduits that have cross-sectional areas and wall thicknesses that are optimized for localized operational stress and velocities of fluids (e.g., water, steam and/or other vapors or fluids) encountered during the operation of the header.
• the shaped optimized headers have shells of variable cross-sectional areas and/or wall thicknesses.
• the cross- sectional area of a particular portion of the shell of the header and/or the wall thickness varies in proportion to the localized flow and localized stress due to the combination of cumulative flow in the header of the incoming fluid and of geometry of the connecting tubes, and to the velocity of the fluid and/or the chemical composition of the incoming fluid in that particular portion of the shell.
• the shaped optimized headers are designed in such a manner so as to have larger cross-sectional areas and possibly, larger wall thicknesses (than other cross- sectional areas and wall thicknesses of the same header) only in those localized portions where the header encounters higher stress (due to geometry of incoming tubes) and fluid velocities.
• the resulting shaped optimized headers can have numerous cross-sectional areas and wall thicknesses depending upon the localized stress and fluid velocities encountered during operation.
• shape optimized headers can also use different materials of construction depending upon the chemistry of fluids encountered in different sections.
• the shaped optimized headers can be made of specialized materials that are more expensive than those used in the headers depicted in the Figure 1, but because of the optimized design can cost less than if the header of the Figure 1 were constructed from the same specialized materials.
• headers are also advantageous in that they use less floor space and volumetric space in a plant and can be used in operation for as long or for longer periods of time than headers designed in the manner depicted in the Figure 1.
• the Figure 2 depicts a shape optimized version of the comparative header of the Figure 1.
• the shape optimized header 200 comprises a shell 202 (in the form of a conical section) 202 having a circular cross-sectional internal diameter that varies from a minimum diametric value of di (at the end where the stress and/or fluid flow rate is lowest) to a maximum diametric value d 2 at the opposite end (where the stress and/or fluid flow rate is greatest).
• the wall thickness also varies from a minimum wall thickness of ti (at the end where the stress and/or fluid flow rate is lowest) to a maximum wall thickness of t 2 at the opposite end (where the stress and/or fluid flow rate is greatest).
• the header 200 comprises a first end 206 and a second end 208 that is opposite the first end 206.
• the first end 206 is sealed to the outside (i.e., fluid from the outside cannot enter or leave the shell 202 via the first end 206), while the second end 208 is in
• FIG. 2 depicts a smooth linear variation in the cross-sectional area of the header and a smooth linear variation in the wall thickness from the first end 206 to the second end 208, other variations may also be used.
• the variation in either the cross sectional area or the thickness may be non-linear (e.g., curvilinear, varied according to an exponential or spline function, varied randomly in a discontinuous manner, or
• the inner surface 218 or outer surface 220 of the header 200 may be a continuously varying surface or it may be a discontinuously varying surface (i.e., one with variations that are similar to a step function), or it may be a combination thereof.
• the increase in the diameter and/or in the wall thickness of the shell is proportional to the local increase in the pressure experienced in different sections of the header and can be expressed by the equation (1) as follows:
• the change in diameter and/or the change in the wall thickness of the shell is proportional to a change in local pressure experienced in the shell and determined by the equation (l a):
• Ad 2 is the change in the internal diameter of a second section of the shell
• ⁇ ⁇ is the change in the internal diameter of a first section of the shell
• ⁇ 2 is the change in the wall thickness of a second section of the shell
• ⁇ is the change in the wall thickness of a first section of the shell
• ⁇ 2 is the change in pressure experienced in the second section of the shell
• pi is the change in pressure encountered in the first section of the shell.
• the increase in the diameter and/or in the wall thickness of the shell is proportional to the increase in the fluid flow rate experienced in different sections of the header and can be expressed by the equation (2) as follows:
• d 2 , d 1; t 2 and ft are indicated in the Figure 2 and where f 2 is the maximum fluid flow rate and ft is the minimum fluid flow rate encountered in the different sections of the header.
• a change in diameter and/or a change in a wall thickness of the shell is proportional to a change in fluid flow rate experienced in the shell and determined by the equation (2a):
• Ad 2 is the change in the internal diameter of a second section of the shell
• ⁇ is the change in the internal diameter of a first section of the shell
• At 2 is the change in the wall thickness of a second section of the shell
• Aft is the wall thickness of a first section of the shell
• ⁇ 2 is the change in the fluid flow rate experienced in the second section of the shell
• Aft is the change in the fluid flow rate encountered in the first section of the shell.
• [0]it is desirable to maintain a uniform velocity or fluid flow rate along the length of the header.
• A] and A 2 are the cross-sectional areas of those portions of the shell that encounter the fluid flows ft and f 2 respectively, while di and d 2 are the respective internal diameters of the header at those portions of the shell that encounter the fluid flows ft and f 2 respectively.
• the thickness of the header is varied to maintain uniform stress due to the pressure in the header.
• the stress is equal to the product of pressure and diameter, divided by thickness. In other words, the stress is proportional to diameter but is inversely proportional to thickness as shown in the equations (4) and (5). ⁇ P * d
• p is the pressure in a given portion of the header
• d is the internal diameter of the header
• t is the wall thickness of the header
• d 2 is the internal diameter of a second section of the shell
• dj is the internal diameter of a first section of the shell
• t 2 is the wall thickness of a second section of the shell
• ti is the wall thickness of a first section of the shell
• p 2 is the pressure experienced in the second section of the shell and pi is pressure encountered in the first section of the shell
• ⁇ 2 and ⁇ are the stresses encountered in the second section of the shell and in the first section of the shell respectively.
• the Figure 4 is a front view of an exemplary embodiment that depicts the header 200 of the Figure 2, with the exception that the cross-sectional area of the shell is increased from the first end 206 to the second end 208 in a step-wise manner.
• This increase in the cross- sectional area varies with the increase in the local pressure and/or the fluid flow rate as witnessed in the equations (1) and (2) above.
• the wall thickness t is increased as well to compensate for the increases in the pressure and/or the fluid flow rate.
• the cross-sectional area increases from d ⁇ to d 2 to d and the wall thickness increases from ti to t 2 to t 3 as pressure increases from pi to p 2 to p 3 and/or the fluid flow rate increases from 3 ⁇ 4 to f 2 to f 3 .
• the headers 200 in the Figures 2 and 4 each have a single outlet at the second end 208, there can be two or more outlets if desired.
• the Figure 5 shows headers 200 that have the plurality of outlets.
• the Figure 5A shows a comparative configuration for a header 100 having a plurality of outlets while the Figure 5B shows a shaped optimized configuration for the same header 200 having a plurality of outlets.
• the cross-sectional area of the shell 202 is greatest near the outlets at the first end 206 and the second end 208 since these regions experience the highest pressures and/or fluid flow rates.
• the wall thickness at the outlet regions is greater than the wall thickness at other regions of the header.
• the outlets located near the first end 206 and the second end 208 of the header are used to remove the fluid or vapor being conveyed by the header from the header 200.
• the Figure 6A shows a comparative header along with a shape optimized header for a design having a central tee that serves as the outlet.
• the Figure 6A shows a comparative configuration for a header 100 having the central tee while the Figure 6B shows a shaped optimized configuration for the same header 200 having a single outlet.
• the central tee 212 is used as an outlet in the Figure 6B while it is listed as 112 in the Figure 6 A.
• the cross-sectional area of the shell is greatest at the center of the header because this is the region where the pressure and/or the fluid flow rate is greatest.
• the wall thickness is greatest at the center.
• the wall thickness of the shell is narrowest at the opposite ends 206 and 208 where the pressure and/or the fluid flow rate, is the lowest.
• the wall thickness is determined by the internal pressure that the header has to withstand during normal operation, or as defined by a fault case or other condition as defined by prevailing codes, standards or other design rules. This principle is generally applied to the wall thickness of regions where the tubes are affixed to the wall of the header as well.
• these regions can be weakened by the addition of the tubes to the wall.
• these regions see a greater amount of utility since all of the fluids that enter the header contact the tubes 204.
• the fluids that enter the header also contact the region of the header around the tubes 204 because of the proximity of the region to the point of entry of the fluid. The regions where the fluid enters the header therefore gets weakened more rapidly than other regions of the header.
• the regions where the tubes 204 are affixed to the walls of the header 200 may be increased in thickness in order to provide additional reinforcement to a region that would normally be weakened due to the removal of material to provide paths for entry of fluid from the tubes to the shell.
• the reinforcement also provides a longer life cycle to a region that sees greater usage than other regions during the course of operation of the header. This increase in thickness is local and is undertaken only in an appropriate vicinity to those regions where the tubes 204 are fixedly attached to the header.
• the regions of the wall to which the tubes 204 are fixedly attached are thickened to locally compensate for material removed by forming penetrations for the tubes to communicate with the shell, or to overcome wear and degradation that occurs with increased usage.
• This increase in local thickness provides the header with increased life cycle performance while at the same time reducing the weight of the header and reducing material costs.
• the Figure 7A depicts a cross section of a comparative header wall 100 at the point where the tube 104 contacts the wall of the shell 102.
• the header wall 100 would normally have a thickness of t 4 if the tube 104 were not contacted to the header.
• the thickness of the header wall 100 is increased to t 5 .
• This increase in thickness from t 4 to t 5 in a conventional header causes increases in material costs and in the weight of the finished header.
• Figure 7B depicts a cross sectional view of the wall of a shape optimized header 200.
• the wall thickness for the header is t 4 except in an appropriate vicinity to those regions where the tube 204 is fixedly attached to the header, where it is increased to t 5 . This local increase in thickness ensures uniformity of stress in the header while actually decreasing the weight when compared with the weight of the comparative header of the Figure 7A.
• the shell of the header 200 may be manufactured from iron based alloys, nickel based alloys, tantalum based alloys, and titanium based alloys.
• a shell in the form of a conical section having a smaller diameter di (corresponding to the lower flow rate 3 ⁇ 4) and a larger diameter d 2 (corresponding to the higher flow rate f 2 ) at an end opposed to the smaller diameter d ⁇ has its opposing ends sealed to prevent fluid from inside the shell from contacting the outside.
• An outlet (or an inlet - inlets can also serve as outlets) is then drilled or cut in a portion of the shell. The outlet is used to evacuate the shell of its contents. Holes are drilled in the shell to accommodate the tubes that discharge fluid into the shell.
• a roll of sheet metal e.g., a scroll of metal
• the metal is extended radially outwardly from the center of the scroll in addition to being extended longitudinally so that with each turn of the sheet metal, the diameter of the header increases along with the length.
• the overlapping sheets may be seam welded or riveted together to form the shell of the header.
• the ends of the header may be cut off to form two parallel ends.
• the ends of the header may be welded onto the shell. One end may be sealed against the outside, while the other end has an opening through which the contents of the header are removed for recycling or discharged to waste.
• a scroll of sheet metal of gradually increasing thickness can be used to manufacture the header as described above.
• the thinnest section is held fixed while the thickest section of the scroll is extended outwardly away from the thinnest section to produce a shell of smoothly increasing cross-sectional area and increasing wall thickness as well.
• Holes may be drilled in a surface of the shell in order to fixedly attach the tubes to the header.
• the tubes may be welded onto the shell as shown in the Figures 2 - 5 above.
• the tubes may be screwed into threads formed in the walls of the shell, or welded to the shell.
• the shell may be optionally thickened in the local region surrounding the tubes by using techniques such as laser welding.
• Other techniques used for forming the header and for local reinforcing are conventional casting, spray casting, spray forming and powder metallurgy.
• pipes in another manner of manufacturing a header where the cross-sectional areas increase in a step function manner as seen in the Figure 4 (from those portions of the header that experience lower pressure to those portions of the header that experience higher pressures), pipes (spools) of varying desired diameters and thiclcnesses are first cut and then welded or riveted together to form the header. The ends of the header and the tubes are then welded together to form the header.
• the use of thinner walls and shells reduces thermal stresses and increase the life cycle and the durability of the header or other devices manufactured using these methods and principles.
• Another advantage is that the decreased diameter and wall thickness results in smaller weldments (fewer passes) to joins several spools to form a large header.

Landscapes

• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Mechanical Engineering (AREA)
• Thermal Sciences (AREA)
• Geometry (AREA)
• Pipe Accessories (AREA)
• Branch Pipes, Bends, And The Like (AREA)

Priority Applications (7)

Applications Claiming Priority (1)

Publications (1)

Family

ID=45554789

Family Applications (1)

Country Status (6)

Cited By (1)

Families Citing this family (3)

Citations (5)

Family Cites Families (13)

• 2011
  • 2011-12-21 EP EP11813847.8A patent/EP2798269A1/en not_active Ceased
  • 2011-12-21 WO PCT/US2011/066425 patent/WO2013095424A1/en active Application Filing
  • 2011-12-21 KR KR1020147019608A patent/KR101736559B1/ko active IP Right Grant
  • 2011-12-21 CN CN201180075748.2A patent/CN104024731B/zh not_active Expired - Fee Related
  • 2011-12-21 JP JP2014548756A patent/JP6209531B2/ja not_active Expired - Fee Related
• 2014
  • 2014-05-16 ZA ZA2014/03568A patent/ZA201403568B/en unknown

Patent Citations (5)

Also Published As

Similar Documents

Legal Events