HK1151496B - A flow control method and apparatus - Google Patents

Description

Flow control method and apparatus

Disclosure of Invention

Apparatus for redirecting fluid flow in a plenum provides flow performance (characteristics), structural and economic advantages by utilizing a flat blade array mounted at an angle relative to the inlet (upstream) fluid flow such that the blades are inclined with respect to the flow and accordingly redirect the flow in a desired direction. This device, which may also be referred to as a "GSG" or a "graded straightening grid," has a wide range of applications and offers many performance, structural and economic advantages in large scale applications. As a specific but non-limiting example, one or more embodiments of flow redirection taught herein are configured for Selective Catalytic Reactors (SCR), such as for scrubbing of industrial flue gases.

In at least one embodiment, an apparatus for redirecting fluid flow in a plenum from a first flow direction to a second flow direction includes a transverse array of flat vanes positioned at an angle oblique to the first flow direction to redirect fluid flow from the first flow direction to the second flow direction. In this sense, "transverse" means that the length direction of the blade is transverse to the direction of flow being redirected. In this way, the angle of inclination presents an inclined grading surface to the inlet/upstream flow such that the wind-facing face of each blade in the array redirects a portion of the flow in a desired direction.

In another embodiment, a method of designing a transverse array of flat vanes for redirecting fluid flow in a plenum from a first flow direction to a second flow direction includes defining a transverse vane length as a function of an internal cross-section at a location within the plenum where the transverse array is to be installed, and adjusting at least one of a vane height, a vane spacing, and a vane angle as needed to achieve desired flow characteristics of the fluid flow. The method may include adjusting the vane angle by adjusting a planned (planed) installation angle of the transverse array within the plenum.

In one or more such embodiments, adjusting at least one of the blade height, blade spacing, and blade angle as needed to achieve the desired flow characteristics for the fluid flow includes simulating the fluid flow in a simulation model of the transverse array, evaluating the modeled flow characteristics relative to one or more characteristic requirements, and adjusting one or more of the modeled blade height, modeled blade spacing, and modeled blade angle until the modeled flow characteristics satisfy the one or more flow characteristic requirements. Such a process may be partially or wholly automated, for example by configuring a simulation model with design requirements and specifying preferred design tradeoffs (e.g. blade height-to-pitch adjustment range), and configuring the simulation to tune the array design with respect to flow characteristic requirements. Design requirements may include structural details including dimensions, allowable array weight, structural fastening/support details, stiffness, etc.

Of course, those skilled in the art will recognize additional features and advantages upon reading the following detailed description, and upon viewing the accompanying drawings.

Drawings

FIG. 1 is a simplified side view of one embodiment of a transverse array for flow redirection, shown in a plenum.

FIG. 2 is a simplified side view of a blade detail for one or more embodiments of the array shown in FIG. 1.

FIG. 3 is a simplified perspective view of one embodiment of a transverse array, particularly illustrating flat blades for flow redirection.

FIG. 4 is a simplified plan view of one embodiment of a lateral array.

Fig. 5 and 6 are logic flow diagrams illustrating processing logic, such as may be implemented in a computer system, for one or more embodiments of a method of designing a lateral array for flow redirection.

Fig. 7-9 are installation schematics showing various embodiments of a transverse array installed in a plenum for a Selective Catalytic Reactor (SCR).

Detailed Description

Fig. 1 shows a lateral array 10, which is also referred to as a "graded straightening grid", or simply "array 10". From this schematic view, it can be seen that the array 10 includes a plurality of spaced apart flat blades 12. The array 10 is configured for fixed mounting in a plenum 14 for redirecting fluid flow from a first flow direction to a second flow direction. In particular, it should be appreciated that the novel apparatus shown for redirecting fluid flow provides high downstream flow characteristics in the second flow direction without the need for additional straightening vanes (straightening vanes) downstream of the array 10.

The schematic shows a side view of the array 10 and it will be appreciated that the viewer sees an "end view" of the blades 12, with the blades 12 oriented lengthwise transverse to the first flow direction. Further, as shown in this schematic view, one exemplary installation of the array 10 is at a corner location or junction of the plenums 14, wherein the first plenum section 16 is oriented in a first flow direction and the second plenum section 18 is oriented in a second flow direction. Thus, the array 10 in this example is configured to redirect fluid flow at the corner connection between the first and second plenum sections 16 and 18.

It can be seen that an exemplary angle of inclination relative to the first flow direction for mounting the array 10 is the "corner angle" at the corner connection between the plenum sections 16 and 18. It can be seen that the upstream blade edges of the blades 12 define a plane and, in at least some design applications, it is preferred to align the plane along a corner diagonal 20 extending from an interior plenum corner 22 to an exterior plenum corner 24.

Of course, it should be understood that other alignments may be used and that the array 10 may be raised or lowered relative to the corner centerline as a "tuning" parameter for achieving desired flow characteristics, ease of installation, etc. Further, the angle of the array 10 with respect to the first flow direction may be increased or decreased as a performance tuning parameter, so the tilt angle does not have to follow the inside-to-outside corner angle. Still further, it should be understood that the array 10 may be configured for direction changes other than 90 degrees, such as corners less than 90 degrees, and that the mounting angles and corner positioning may be varied as desired for flow characteristics and mechanical considerations.

Turning to fig. 2, it can be seen that an enlarged side view of some of the blades 12 of a given embodiment of the array 10 is included. In particular, for ease of reference and not by way of limitation, it can be seen that the lateral faces of each blade 12 can be considered as the windward face 30 and the opposite leeward face 32 facing the fluid flowing in the first flow direction. For further reference, each vane 12 is considered to have an upstream (lateral) edge 34 associated with an inlet/upstream first flow direction and a downstream (lateral) edge 36 associated with an outlet/downstream second flow direction. These upstream and downstream blade edges 34 and 36 may or may not be machined or shaped to an aerodynamic profile. In practice, unfinished square edges such as those associated with thick steel plates generally provide acceptable performance. However, some devices with higher flow rates, thicker blades, etc. may benefit from shaped blade edges.

In a general aspect of the array configuration, one or more embodiments of the array 10 are based on a blade height "h" in a range from about 6 inches to about 18 inches, measured from the upstream blade edge 34 to the downstream blade edge 36, and a blade pitch "c" in a range from about 3 inches to about 24 inches between adjacent blades 12 of the array 10. Further, the angle of inclination, i.e., the mounting angle of the array 10 with respect to the first flow direction, may be selected to place the blades 12 of the array 10 at a blade angle θ in the range of from about-25 degrees to about +25 degrees.

Of course, whether or not the parameters are set within the above ranges, it should be understood that the array 10 may be "tuned" by adjusting one or more of such parameters as needed for a given installation requirement. Such adjustments may fix one or more of such parameters and change one or more other parameters in an iterative manner to achieve a design solution that yields acceptable flow characteristics while meeting all practical cost and mechanical considerations.

In at least one embodiment, the preferred blade height "h" is 12 inches or about 12 inches, the preferred blade pitch "c" is 6 inches or about 6 inches, and the preferred blade angle θ is 19 degrees or about 19 degrees. In fig. 2, it can be seen that the blade angle is the blade angle measured between a line extending from the upstream blade edge 34 to the downstream blade edge 36 and a line parallel to the second flow direction. Thus, if the second flow direction is vertical, then the preferred blade angle is 19 degrees or about 19 degrees from the vertical. More broadly, the angle of inclination of the array 10 is selected to position each blade 12 in the array 10 at a blade angle θ between-25 degrees (including-25 degrees) and +25 degrees (including +25 degrees) relative to the second flow direction, where the blade angle θ, as explained, is measured relative to the second flow direction using a straight line connecting the upstream and downstream blade edges 34 and 36.

Further, with respect to array design considerations, in one embodiment, the blade height, measured from the upstream blade edge 34 to the downstream blade edge 36, is configured to be approximately twice the blade pitch, measured between adjacent blades 12 of the array 10. Mathematically, h is 2 c. In another embodiment, the ratio is set to 2.5 times, i.e., h is 2.5 c. For at least some devices, a 2-fold ratio is preferred, however, it should be understood that the height to pitch ratio is a candidate tuning parameter and can be manipulated as part of the design process herein. For example, weight and/or cost limitations may require a smaller number of blades, which means that for a given array dimension, the blade pitch is increased. In such a case, for example, the overall array mounting angle may be varied, and/or the blade height may be varied to compensate for the reduced blade count.

Turning to FIG. 3, it can be seen that a simplified perspective view of the blades 12 in a given array 10 highlights the transverse orientation of the length of the blades 12 and further illustrates the deflection of the blade upwind 30 of the flowing fluid from the first flow direction to the second flow direction. Although the downwind face 32 is not visible in FIG. 3, one or more embodiments contemplated herein include structural reinforcements integrated or mounted on the downwind face 32 of the blade 12. (such structural reinforcements are shown later, for large SCR applications.)

With respect to other mechanical and structural considerations, it should be noted that the term "plenum" will be given a broad structure herein. For example, definitions contemplated herein include, but are not limited to, fluid-filled spaces (e.g., gas, air, etc.) in a structure, particularly, conduits or other channels that convey flowing fluids. Further, unless otherwise specified, the term does not necessarily imply a continuous conduit. For example, a first closed structure (e.g., a duct) may open into a second closed structure (e.g., a space above an SCR group), and all or part of the first and second structures may be considered a plenum 14 in which the array 10 is installed.

Further, it should be understood that the mounting characteristics of the array 10 may be adapted as desired to the particular conditions of the plenum 14 in which it is installed. For example, FIG. 4 illustrates a plan view of a given array 10, which not only illustrates the transverse orientation of the blades 12, but also illustrates a perimeter frame 40 that serves as a carrier for the blades 12 and may be used to secure the array 10 in the plenum 14. Thus, in one or more embodiments, the array 10 includes at least a portion of a perimeter frame 40 for structurally securing the array 10 in the plenum 14. Again, it should be understood that the array 10 may include two or more sub-arrays. For example, for very large plenum cross sections, many smaller arrays 10 may be used to form a larger array across the desired interior space. This may provide, for example, greater structural integrity and limit the individual blade lengths to more practical values.

Still further, it should be understood that in one or more embodiments, the blades 12 are uniformly spaced apart in the array 10. However, in one or more other embodiments, the blades 12 are non-uniformly spaced apart in the array 10. In still other embodiments, a portion of blades 12 may be uniformly spaced, while another portion may be non-uniformly spaced. Such variations may be employed to allow for structural mounting to accommodate obstructions and the like.

Of course, all of the design parameters may be set and adjusted as needed for a given installation. Indeed, one aspect of the teachings herein includes a design methodology whereby computer simulation (and/or experimental level modeling) and parameter adjustment results in an array 10 configured given the requirements of a particular plant. Such simulations may be based on Computational Fluid Dynamics (CFD) modeling and/or experimental-level modeling, and may be completed in whole or in part on a computer system, such as a PC, having a computer-readable medium having program instructions thereon for implementing an array adjustment method in a flow simulation environment.

FIG. 5 illustrates one embodiment of such a method, where processing "begins" by inputting design requirements (block 100). Such a requirement may be a desired flow characteristic in the second direction, which may be expressed in terms of laminar flow characteristics, turbulence values, etc. Such requirements will generally include basic plenum dimensions, flow volumes, velocities, etc., the basic design requirements being mastered, and the method of designing the array 10 includes defining the transverse vane length "L" as a function of the internal cross-section at the location within the plenum 14 where the array 10 is installed (block 102). Processing continues by adjusting at least one of the blade height, blade pitch, and blade angle as needed to achieve the desired flow characteristics for the fluid flow (block 104).

Such processing may be iterative and may be driven by or using command scripts or other program controls that step through a range of design parameter selection for any one or more tuning parameters (e.g., blade height, pitch, angle, total blade number, etc.) until the design requirements are met. Again, such processing may be carried out by computer simulation in a flow modeling simulation environment or in experimental scale modeling.

FIG. 6 illustrates one embodiment of iterative array adjustment. This process may represent the details of block 104 of FIG. 5. The array design may be initialized by utilizing default or nominal array parameters, such as default blade height, pitch, and angle (block 110). Processing continues by adjusting one or more parameters based on known primary parameters (overrides), such as forced blade spacing (block 112). Processing continues by running/evaluating the corresponding simulation model (block 114).

The assessment includes, for example, comparing the simulated flow characteristics to design requirements. If the design criteria are met (within some acceptable range of the variables) (block 116), the process "ends". If the design criteria are not met, and if iteration limits or other processing constraints are not exceeded (block 118), processing continues by adjusting one or more array parameters and running/re-evaluating the re-adjusted simulation model (block 120). Such iterative adjustments continue as needed or until the iteration constraints are exceeded.

In one or more embodiments, adjusting the array 10 includes adjusting the vane angle by adjusting the planar (planed) mounting angle of the pressure array 10 within the ventilation system 14. The adjustment may alternatively or additionally include adjusting at least one of the blade height, blade pitch, and blade angle as needed to achieve a desired flow characteristic of the fluid flow. Again, such adjustments may include simulating fluid flow in a simulation model of the array 10, assessing modeled flow characteristics relative to one or more characteristic requirements, and adjusting one or more of modeled vane height, modeled vane spacing, and modeled vane angle until the modeled flow characteristics satisfy the one or more flow characteristic requirements. Further, as noted, adjusting at least one of the blade height, blade pitch, and blade angle as needed to achieve the desired flow characteristics of the fluid flow may include initializing a transverse array design with a default blade height, default blade pitch, and default blade angle, and then adjusting one or more of these default values.

Such default values may be based on setting the default blade height and the default blade spacing according to a blade height to blade spacing ratio of approximately 2: 1. Further, the adjustment range of one or more adjustment variables may be constrained to be within the previously mentioned ranges of blade height, pitch, and angle.

In view of such design flexibility, fig. 7, 8 and 9 illustrate application examples in which the array 10 is configured for various SCR applications. In particular, FIG. 7 highlights the structural reinforcement of the leeward side on the blade 12 and shows the mechanical mounting characteristics. In these schematic illustrations plenum 14 includes elements upstream of Selective Catalytic Reactor (SCR)50, array 10 is configured to redirect gas flow to SCR 50.

However, the array 10 is not limited to the illustrated example. More generally, it should be understood that the foregoing description and accompanying drawings represent non-limiting examples of the methods, systems, and individual devices taught herein. As such, the invention is not limited by the foregoing description and accompanying drawings. Rather, the invention is limited only by the claims and their legal equivalents.

Claims (21)

1. An apparatus for redirecting fluid flow in a plenum of a selective catalytic reactor, the apparatus capable of redirecting fluid flow from a first flow direction to a second flow direction, the apparatus comprising a transverse array of flat vanes positioned at an oblique angle relative to the first flow direction to redirect the fluid flow from the first flow direction to the second flow direction,

wherein the apparatus is configured to redirect the fluid flow at a corner connection between first and second plenum sections, the first plenum section flowing in the first flow direction of the transport fluid and the second plenum section flowing in the second flow direction of the transport fluid;

wherein the plane defined by the transverse array is adjustable to achieve at least one flow characteristic by adjusting the planar mounting angle of the transverse array within the plenum and aligned along the diagonal of the corner connection; and is

The plane is defined by upstream edges of the vanes in the transverse array, and wherein the angle of inclination represents a measure of the angle between the first flow direction and the plane.

2. The apparatus of claim 1, wherein the lateral array is positioned with the planes aligned on a diagonal extending from an interior corner to an exterior corner of the corner junction.

3. The apparatus of claim 1, wherein a blade height measured from an upstream blade edge to a downstream blade edge is in a range from six inches to eighteen inches, a blade pitch between adjacent blades in the transverse array is in a range between three inches to twenty-four inches, and wherein the inclination angle is selected to arrange the blades in the transverse array at a blade angle in a range from fifteen degrees to twenty-five degrees.

4. The apparatus of claim 3, wherein the blade height is twelve inches, the blade pitch is six inches, and the blade angle is nineteen degrees.

5. The apparatus of claim 1, wherein a blade height measured from an upstream blade edge to a downstream blade edge is configured to be twice a blade pitch measured between adjacent blades in the transverse array.

6. The apparatus of claim 5, wherein the angle of inclination is selected to position each vane in the transverse array at a vane angle between negative twenty-five degrees and positive twenty-five degrees relative to the second flow direction, wherein the vane angle is measured relative to the second flow direction using a line connecting the upstream vane edge and the downstream vane edge.

7. Apparatus according to claim 1, wherein one or more blades comprise a structural reinforcement integrated with or mounted on the downwind face of the blade, wherein the downwind face of the blade is the side of the blade facing away from the first flow direction.

8. The apparatus of claim 1, wherein the transverse array comprises at least a partial perimeter frame for structurally securing the transverse array in a plenum.

9. The apparatus of claim 1, wherein the lateral array comprises two or more sub-arrays.

10. The apparatus of claim 1, wherein the vanes are uniformly spaced within the transverse array.

11. The apparatus of claim 1, wherein the vanes are non-uniformly spaced in the transverse array.

12. The apparatus of claim 1, wherein the plenum comprises an upstream element of a selective catalytic reactor, and wherein the transverse array is configured to redirect gas flow into the selective catalytic reactor.

13. A method of designing a transverse array of flat vanes for redirecting fluid flow in a plenum from a first flow direction to a second flow direction in a selective catalytic reactor, the method comprising:

selecting a corner connection between first and second plenum sections, the first plenum section flowing in the first flow direction of the transport fluid and the second plenum section flowing in the second flow direction of the transport fluid, wherein a plane defined by the transverse array is adjustable by adjusting a planar mounting angle of the transverse array within the plenum to achieve at least one flow characteristic and is aligned along a diagonal of the corner connection, and wherein the plane is defined by upstream edges of the vanes in the transverse array, and wherein an angle of inclination represents a measure of the angle between the first flow direction and the plane;

defining a transverse vane length as a function of an interior cross-section at a corner connection location within the plenum where the transverse array is mounted; and

at least one of blade height, blade pitch, and blade angle are adjusted as needed to achieve desired flow characteristics of the fluid flow while redirecting fluid flow in the plenum.

14. The method of claim 13, further comprising adjusting a blade angle by adjusting a planned installation angle of the transverse array within the plenum.

15. The method of claim 13, wherein adjusting at least one of blade height, blade pitch, and blade angle as needed to achieve a desired flow characteristic of the fluid flow comprises simulating the fluid flow in a simulation model of the transverse array, assessing the modeled flow characteristic relative to one or more characteristic requirements; and adjusting one or more of the modeled blade height, the modeled blade pitch, and the modeled blade angle until the modeled flow characteristic satisfies one or more flow characteristic requirements.

16. The method of claim 15, wherein adjusting at least one of the blade height, blade pitch, and blade angle as needed to achieve desired flow characteristics of the fluid flow comprises initializing a transverse array design with a default blade height, a default blade pitch, and a default blade angle.

17. The method of claim 16, further comprising setting a default blade height and a default blade pitch according to a 2: 1 blade height to blade pitch ratio.

18. The method of claim 16, further comprising setting a default blade height of 12 inches and correspondingly setting a default blade pitch of 6 inches.

19. The method of claim 16, further comprising setting a default blade angle to nineteen degrees relative to the second flow direction.

20. The method of claim 15, wherein initializing a transverse array design with a default blade height, a default blade pitch, and a default blade angle comprises setting the default blade height to a value in a range from 6 inches to 18 inches, setting the default blade pitch to a range from 3 inches to 24 inches, and setting the default blade angle to a range from-25 degrees to +25 degrees.

21. The method of claim 13, further comprising adjusting the actual blade pitch away from the default blade pitch to reduce the total blade count for the transverse array while compensating for the increased blade pitch by adjusting one or both of the blade height and the blade angle accordingly.