US20030054300A1

US20030054300A1 - Apparatus having similar interstitial passages

Info

Publication number: US20030054300A1
Application number: US09/952,607
Authority: US
Inventors: Marco Castaldi; Lance Smith; William Pfefferle
Original assignee: Precision Combustion Inc
Current assignee: Precision Combustion Inc
Priority date: 2001-09-15
Filing date: 2001-09-15
Publication date: 2003-03-20

Abstract

The invention disclosed herein is a method and apparatus for use therewith for creating flow passages of approximately equal cross section whereby a flow of a fluid through any passage will be approximately equal to the flow of a fluid through another passage.

Description

FIELD OF THE INVENTION

The present invention is generally directed to equalizing the flow within a plurality of passages, and more specifically to extending a pattern defined by a tube bundle into the housing into which the tube bundle is positioned.

BACKGROUND OF THE INVENTION

A catalytic reactor is a device that has a catalyst therein that facilitates a chemical reaction. Generally, the main components of a catalytic reactor are a housing surrounding a support onto which the catalyst is positioned. The support is commonly referred to as a substrate. Substrates vary widely. Some of the more basic substrates are pellets, monoliths, gauzes or screens. More complex substrates can be enclosed passages such as tubes.

Catalytic reactors that employ enclosed passages are disclosed in U.S. patent application Ser. No. 09/527,708 entitled “Method and Apparatus for a Fuel-Rich Catalytic Reactor” and U.S. Pat. No. 6,174,159 entitled “Method and Apparatus for a Catalytic Firebox Reactor,” both assigned to the assignee of the present application, namely Precision Combustion, Inc., and both incorporated herein by reference in their entirety. Both of these catalytic reactors use elongated bodies having passages, e.g. tubes, spaced apart relative one to the other and positioned within a housing thereby defining a single flow channel. The catalyst is positioned on the outer surface of at least one tube within the single flow channel.

When similar tubes, e.g. straight with a circular cross section, are packed to form a bundle within a housing such as in the above-identified catalytic reactors, interstitial areas are created. More specifically, the tubes in the bundle are positioned along a coordinate direction longitudinal of the housing with the interstitial areas being between the tubes and best visualized along a plane perpendicular to the coordinate direction. There are two general categories of interstitial areas—those between the tubes relative one to the other and those between the tubes and the housing.

In a uniform tube-packing scheme, i.e. where the tubes are uniformly spaced one to the other, the interstitial areas between the tubes are of uniform cross section and in turn define interstitial passages of uniform cross section. When the bundle is placed within the housing, the interstitial areas defined by the tubes and housing can be of any cross section but will be different from the cross section of the interstitial areas between the tubes. If the housing is uniform around the bundle, the interstitial areas defined by the tubes and the housing will be uniform. As a result of the cross-sectional differences between the interstitial areas, at least two different type flow channels within the housing are defined. Therefore, when these tube type reactors are placed in a fluid flow stream, the different flow channels impart to a fluid flowing therethrough distinctly different flow characteristics.

In the above-identified tube reactors, the fluid flowing in the single flow passage will be combined with another fluid flowing in the tubes at the reactor's downstream exit. This is accomplished by co-locating and interspersing the exits of each flow channel within the single flow channel and the exits of the tubes creating a point of confluence for the two fluid streams. If the flow characteristics of the flow channels are not uniform, mixing of the fluid exiting the flow channels with the fluid exiting the tubes will not be uniform potentially causing the two fluid streams to not mix as desired.

Based on the foregoing, it is the general object of the present invention to provide an apparatus that overcomes the problems and drawbacks of the prior art.

SUMMARY OF THE INVENTION

The present invention is directed in one aspect to an apparatus for defining relatively similar interstitial passages. The apparatus has a housing with a plurality of tubes defining a bundle wherein the tubes cooperate to define a repeating interstitial pattern. In the apparatus, the housing is contoured such that the repeating interstitial pattern defined by the tubes is continued in the area between the bundle and the housing. While the invention is being depicted in the context of a catalytic reactor the invention should not be so limited as it could also find utility in heat exchangers and other similar devices wherein there is a defined repeating interstitial pattern.

In the present invention, a plurality of tubes in the form of a bundle are positioned within a housing along a coordinate direction longitudinal of the housing. The tubes are positioned in a pattern such that there is a generally uniform repeating interstitial area between adjacent tubes in a cross section taken perpendicular to the coordinate direction, which define generally identical flow channels. The bundle has a perimeter defined by an outer row of tubes and the housing is contoured such that the contours and the outer row of tubes establish the same pattern formed between adjacent tube rows within the bundle, i.e. a pattern consistent with a next hypothetical row of tubes that would form part of the bundle.

The tubes can be positioned in almost any repeating pattern such as triangles and rectangles. Non-uniform patterns that produce a repeating pattern of interstitial areas are also permitted. The tubes can touch to define discrete flow passages or can be positioned to define a single flow channel such as depicted in the incorporated application and patent.

There is considerable flexibility permitted in the contouring of the housing. For example, the contouring may be done throughout the length of the bundle or only within a portion of the length of the bundle. It is also possible to continue the contouring originating within the length of the bundle outside the length of the bundle. In some cases it might be desirable to only have the housing contoured in the area of the end of the bundle.

The housing can be contoured in numerous ways. For example, a body can be either attached to or made part of the housing with each body having a profile that is the same as the profile of the next hypothetical tube. The housing could also be cased or machined to have the contours.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of an apparatus of the present invention. [0013]
FIG. 2 is an end view of the apparatus of FIG. 1. [0014]
FIG. 3 is an end view of a second embodiment of the apparatus. [0015]
FIG. 4 is an cross-sectional view of a third embodiment of the present invention.[0016]

DETAILED DESCRIPTION

As shown in FIG. 1, the apparatus generally denoted by reference number [0017] 9 is comprised of a plurality of tubes 10 defining a bundle 11 positioned within a volume 12 defined by housing 14 having an inner surface 16 and a length 18. Each tube 10 has an outer surface 20 and a length 22. Referring to FIG. 2, the apparatus has seven tubes 10 in a close packed configuration, meaning that the outer surfaces 20 of adjacent tubes 10 are in contact and the outer surface 20 of the tubes 10 adjacent to the inner surface 16 and the inner surface 16 are in contact. A body 24 is attached to the inner surface 16 having a terminus 26 positioned approximately at a tube outlet 28.
Continuing with FIG. 2, the apparatus [0018] 9 has seven tubes 10 configured in a pattern of a ring of six tubes 10 around a single center tube 10. Adding additional rings of tubes could extend this pattern. The outer surfaces 20 of the tubes 10 in the ring define a perimeter 31. This pattern defines two interstitial areas, the first interstitial areas 30 and the second interstitial areas 32. The first interstitial areas 30 are defined by the outer surfaces 20 of adjacent tubes 10. The second interstitial areas 32 are defined by the outer surfaces 20 of tubes 10 closest to the inner surface 16 and by the inner surface 16. The second interstitial areas 32 are of a different cross section than the first interstitial areas 30.
The [0019] tubes 10 define a uniform repeating first interstitial pattern. However, this is not a requirement of the invention as any repeating first interstitial pattern is acceptable. In addition while the term tube has a cylindrical connotation, that is not considered a limitation of this invention, and the term tube should not be so limited.
Referring to FIG. 2, a [0020] catalyst 36 is positioned on the outer surface 20 of a tube 10. It is understood, however, that positioning of a catalyst 36 at the outer surface 20 is not required, nor should the invention be considered so limited. The catalyst 36 can be positioned on any surface of the tube 10. As those skilled in the art will readily recognize there are numerous ways to position a catalyst 36 at the surface of the tube including but not limited to deposition on to the tube material and integration into the tube material.
A [0021] body 24 is disposed in fixed position within each second interstitial area 32. The body is fixed in position relative to the inner surface 16 of the housing 14. The body 24 has a cross-section 40 that is the same as the cross section a hypothetical tube 10 would have if positioned in this location to continue the tube pattern. The body 24 further sub-divides the second interstitial areas 32 creating a third interstitial area 42 having a cross-section similar to, if not identical to, the first interstitial areas 30.
As shown in FIG. 1, the [0022] body 24 has a length 46 that places the body 24 at the tube outlets 28. This is not a requirement as the length and position of the body 28 can be adjusted based on the application. In some applications, the body 24 might extend the length of the bundle 11, or only a portion of the bundle 11. In addition, the body 24 might extend from along the length of the bundle 11 to outside the bundle 11 or be intermittently placed along the bundle 11. The body 24 need only continue the pattern within at least one cross section within the housing 14.
FIG. 3 shows the [0023] tubes 10 packed within a hexagonal housing 14. It should be noted that a body 24 is not placed within every second interstitial area 32, such as the interstitial areas at the corners of the hexagon. While it is preferred that all second interstitial areas 32 be sub-dividable into third interstitial areas 42 consistent with the interstitial pattern, it is not required. For the invention, only a majority of the second interstitial area 32 is required to be divided. Where a second interstitial area 32 can not be properly subdivided, consideration should be given to blocking that flow channel.
FIG. 4 depicts a tube packing arrangement wherein the [0024] tube 10 outer surfaces 20 do not touch and the tube outer surfaces 20 do not touch the housing inner surface 38. The tube pattern defines first interstitial areas 38, denoted by dotted lines 48 and 50, and second interstitial areas 32, and denoted by dotted lines 50 and 52. Note that in this arrangement the various interstitial areas are in fluid communication. Placement of the bodies 24 subdivides the second interstitial areas 32 into third interstitial areas 42, denoted by dotted lines 50 and 54, and 52 and 54. Note how the third interstitial areas 42 have similar cross-sections 56 and 58 to the first interstitial areas 30.
Although the present invention has been described in considerable detail with reference to certain preferred versions thereof, other versions are possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the preferred versions contained herein. [0025]

Claims

What is claimed is:

1. An apparatus having relatively similar interstitial passages comprising:

a housing having an inner surface,

a plurality of elongated bodies having passages defining a bundle having a perimeter, the passages cooperating to define a repeating first interstitial area; and

at least a portion of the housing inner surface being contoured to generally repeat the first interstitial pattern between the perimeter and the inner surface.

2. The apparatus of claim 1 wherein the bundle has a length and the housing is contoured throughout the length.

3. The apparatus of claim 1 wherein the bundle has a terminus and the housing is contoured at the terminus.

4. The apparatus of claim 1 wherein the passages cooperate to define a single flow channel.

5. The apparatus of claim 4 wherein a passage has a catalyst positioned thereon on a surface that defines the single flow channel.

6. The method of equalizing the flow within a catalytic reactor comprising:

providing a catalytic reactor comprising a housing having an interior surface defining a volume and a plurality of passages defining a bundle having a catalyst positioned thereon, the passages cooperating to define a repeating interstitial pattern; and the housing contoured to repeat the interstitial pattern between the bundle and the housing.

7. The method of equalizing the flow within a catalytic reactor of claim 6 wherein the passages define discrete flow passages.

8. The method of equalizing the flow within a catalytic reactor of claim 6 wherein the passages cooperate to define a single flow channel.