GB2224341A - Heat transfer or chemical tower packing element - Google Patents

Description

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HEAT TRANSFER OR TOWER PACKING ELEMENT BACKGROUND OF THE INVENTION

Tower packing elements and heat transfer elements exist in the prior art. In the case of heat transfer elements, such are frequently used in large numbers, to comprise heat transfer beds. For example, some heat transfer elements are made of ceramic or stoneware, and are used such that f umes or odors are delivered into a combustion chamber, wherein the same are burnt at a sufficiently high temperature that substantially all that is released into the atmosphere is converted to carbon dioxide and water. In the passage of such gases into the combustion chamber, they generally preliminary pass through stoneware beds, which beds have been pre-heated so that they can, in turn, pre-heat the incoming gases so that combustion is assured as soon as the incoming gases pass into the combustion chamber. In such uses of heat transfer elements, the flow of gases is periodically reversed, such that gases from the combustion chamber also pass outwardly through the stoneware chamber to preheat the stones or elements in the chamber, as the products of combustion pass outwardly on their way to atmosphere. In such devices, the combustion processes alternate the flow through the recovery chambers having the elements therein, such that the elements alternately pre-heat the incoming gases or are themselves heated by

2224341 outgoing gases. An example of such a system is that disclosed in U.S. Patent 3,895,918 issued to James H. Mueller on July 22, 1975.

It is also known to use elements as tower packing, such as for gas scrubbers or other industrial equipment, in which the elements are generally randomly dumped or stacked in an arranged manner to allow for flow of fluids therethrough, and often generally to allow for flow of fluids in opposite directions simultaneously therethrough, such as in liquid-gas contact systems, liquid contact systems, and fluid-fluid contact systems. Often such systems are used to collect impurities of smokestack effluent or the like, rather than discharge the same to atmosphere. An example of a tower packing element of saddle configuration is that disclosed in U.S. Patent 4,155,960. Other examples of tower packing elements are disclosed in U.S. Patents 4,333,892, 4,303,599 and 4, 316,863.

Whether the elements are used for tower packing, or for heat retention/transfer, certain considerations exist that are common to each type of use of the elements. For example, one factor of interest in both systems of use woud be the amount of surface area afforded by the elements; another factor would be the amount of mass of the elements; the geometric shapes provide yet another 1 1 3 factor; pressure drop through the chamber or tower in which the elements are dumped or arranged provides yet another factor; still another factor is the inherent strength of the elements to support each other in a packed tower or packed chamber arrangement; yet another factor is the ability of the elements to remain intact, without breakage, when dumped from above to fill a chamber or packed tower; another factor resides in economy of manufacture. These and other factors or features of such elements, it will be seen, have commonality regardless of the application of the elements for heat transfer or for t9wer packing.

SUMMARY OF THE INVENTION

The present invention is directed to providing elements for use as heat transfer or chemical tower packing material, preferably for use in a dumped tower or chamber arrangement.

Accordingly, it is a primary object of this invention to provide a novel configuration for a heat transfer or tower packing element.

It is a further object of this invention to accomplish the above object, wherein a three-dimensional, solid shape is provided of a suitable material of 4 composition, wherein the configuration of the element is generally cylindrical, comprised of radial portions emanating f rom a core and terminating outwardly in an enlarged portion to provide a plurality of 'IT" shaped cross-sections that aggregately define a cylindrical configuration.

It is a further object to accomplish the above, wherein longitudinal channels are disposed between "T" shaped portions.

It is another object to accomplish the above, wherein the material of construction is a mineral, at least in part of metal, clay, ceramic, formed plastic with fiberglas imbedments, or other synthetic material.

It is yet another object of this invention to accomplish the objects set forth above, wherein the elements have surface/weight ratios in square feet/pound within the range of about 1.20 to about 1.56.

It is a further objection of this invention to accomplish any of the objects set forth above, wherein the elements, in cross-section, are about 65% open, to allow for fluid flow therethrough.

-1 It is another object of this invention to accomplish any of the objects set forth above, wherein the elements may have various diameter to length ratios depending upon their desired end uses.

other objects and advantages of the present invention will be readily apparent to those skilled in the art from a reading of the following brief descriptions of the drawing figures, the detailed descriptions of the preferred embodiments, and the appended claims.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

Fig. 1 is a perspective view of an element in accordance with this invention.

Fig. 2 is an end view of the element of Fig, 1.

Fig. 3 is a left side, elevational view of the element of Fig. 2.

Figs. 4 to 8 are enlarged, fragmentary end elevational views of alternative embodiments of the "T" shaped portions of alternative element configurations.

i 6 Fig. 9 is a schematic perspective view, partially broken away, of an incineration apparatus with which the elements in accordance with this invention are used as a heat transfer media.

Fig. 10 is a graph showing the surface to weight ratios of elements in accordance with this invention, for a range of diameter to length ratios.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Preparatory to describing the constructions of the elements, per se, reference is first made to Fig. 9, wherein an incineration apparatus is generally designated by the number 10, as comprising a high temperature combustion chamber 11 having a plurality of energy recovery chambers 12 disposed thereabout, separated therefrom by a wall 13. The wall 13 is shown in Fig. 9 to have convex sides or faces 15 and concave sides or faces 16. The elements 17 within the chambers 12 exert forces of weight or gravity against the convex faces 15 of the wall 13 that keep the individual blocks 18 under compression. The blocks 18 have perforations (not shown) in them for passage of gases therethrough, from the concave faces 16 to the convex faces 15, and the reverse, as will be explained hereinafter, and are generally constructed of refractory material, laid in generally A 1 7 horizontal rows, with each row comprising a plurality of blocks, and with adjacent rows being in staggard relation to each other.

The combustion chamber 11 has one or more burners 22 therein, coming up through the bottom, as illustrated in Fig. 9. Such burners enable the combustion within the combustion chambers to take place at temperatures up to 20000P, or more, depending upon the ingredients of the gases.

Generally, the incoming gases from a suitable factory, plant or the like enter the inlet 23, into the inlet toroid distribution facility 24, by which they may enter via vertical ducts 19, certain ones of the alreadypreheated energy recovery chambers 12, to pass over the pre-heated elements that are piled up therein, so that when such gases enter the combustion chamber by passing through the porous wall portions 14 thereof, into the combustion chamber 11, they may be readily be burned therein, with the gases then passing outwardly through other porous wall portions 13, passing through still other element beds in recovery chambers 12, to serve to heat the elements within such chambers as they pass outwardly therethrough, on theirlway to a discharge duct 8 27, to be discharged via fan or pump-operated duct 28, as shown, to atmosphere, pref erably in the f orm of carbon dioxide and moisture.

It will be seen that various valving arrangements 30 may be used to direct the f low of gases either inwardly through the recovery chambers on their way to combustion chamber 11, or outwardly from the combustion chamber 11, through the recovery chamber 12. as desired, but that, in any given apparatus 10. some of the recovery chambers 12, will, at any given time, be passing gases inwardly, and some will be passing gases outwardly, as will be understood from the prior art discussed above.

Preferably, the blocks 18 that make up the wall portions 13 are porous in the sense that they have perforations through them, which perforations amount to about 30%-40% of the volume of each said block, and in some cases, about 50%-70% of each block.

As constructed, and in accordance with this invention, the apparatus will work such that contaminated fumes or odors may enter the apparatus through the inlet manifold-like ring 24. The valves 30 thus direct such gases containing fumes or the like, into the chambers 12, passing over the elements, and moving the gases toward the incineration chamber. The gases leave the element t! 9 beds 12 at temperatures very close to the incineration temperature. Oxidation is completed in the combustion chamber 11, by means of a gas (or oil) burner that maintains a pre-set incineration temperature. After the burning is effected in the chamber 11, the purified gases are then pulled from such chamber through the element beds, which are at that time in an "outlet" mode, thereby passing heat to the elements, which the elements absorb.

It will be understood that the situation is then reversed, such that a given element bed alternately operates to receive heat from outgoing gases, or to preheat gases, depending upon the settings of the valve 30.

With reference to Figs. 1-3, it will be seen that the bed 12 of elements 17 is one in which the elements 17 have been randomly "dumped" in the parlance of the trade, meaning that they are not precisely arranged geometrically but that they have been provided to the chamber in a gravity fall, such that the elements assume various positions of orientation in their beds. Alternatively, but less customary. particularly when the elements are small in size, the elements may be precisely arranged in a given pattern, if desired.

Each element 17 is geometrically configured, preferably by means of an extrusion process, to include an elongated core portion 50, extending from one face 51 to an opposite face 52 thereof, with a plurality of radial portions 52 emanating radially outwardly from the core portion 50. In the embodiment shown, six radial portions are illustrated, although a greater or lesser number could, if desired, be used. Also, it will be seen that the radial portions 52 are illustrated as being equally- angularly spaced relative to each other, at about 600 apart, although non- uniform spacings may be also be used, if desired.

Each radial portion 52 is provided with an associated peripheral portion 53, such that, as viewed in end view as illustrated in Fig. 2, a given radial portion 52 with an associated periphery portion 53, together comprise a generally "T" shaped cross-section. In the aggregate, such "T" shaped cross-sections, as illustrated in Fig. 2, describe a generally circular configuration, as indicated by the dotted line 54 illustrated in Fig. 2. It will also be noted that the outer surfaces 55 of the periphery portions in the embodiment illustrated in Figs. 1-3, are shown to be arcuate, in conformity with a true cross-section. It will further be noted that such outer surface 55 of each periphery portion need not be truly 4.

11 arcuate, but can be generally configured in various forms, such that the exterior configuration of the elements will still be "generally" cylindrical.

It will further be noted that adjacent 1' T 11 configurations for the element 17 has periphery portions that define longitudinal channels therebetween, to increase the surface area for fluid flow contact therewith, as gases or other fluids flow through a bed of elements.

It will further be noted that in the particular configuration for an element illustrated in Figs. 1-3, the elements appear in cross-section as "wagon wheel" configurations.

With specific reference to Fig. 4, it will be noted that a core portion 58 is provided with a longitudinally co-extensive through-hole 60, generally centrally located therethrough, to facilitate the provision of additional surface area and the passage of fluid therethrough.

With reference to Fig. 5, an alternative periphery portion 61 for an alternate embodiment of the element is provided with a curved peripheral surface 62 that merges 12 gently with curved corner portions 63, as shown, rather than the abrupt intersecting planes illustrated in the embodiment of Fig. 2.

With ref erence to Fig. 6, it will be seen that the periphery portion 64 has a longitudinally f luted outer surface 65 for additional element contact area.

With reference to Fig. 7, another alternative element embodiment is provided with a periphery portion 66 that is generally triangular in cross-section, while still forming a "T" configuration with its radial portion 67, and with a fluted outer peripheral surface 68, for greater strength between the periphery portion and the radial portion, but still with increased surface area on the outer surface of the peripheral portion.

With reference to Fig. 8, another cross-sectional of configuration for the radial and periphery portions of an element is illustrated, with the periphery portion 70 being generally similar to that 61 of Fig. 5, but with the radial portion being curvingly sinusoidal at 71, as shown, for increased surface area contact at the zone of the radial portion surfaces.

3 13 It will thus be seen that various modifications can be made to the elements of the present invention, still retaining the plurality of "T" shaped cross-sections as shown.

It has been f ound that in some embodiments of the element in accordance with this invention, particularly those of one-inch diameter by one-inch length, the area may be up to 0.053 ft2 per element.. to have 65% open area, as viewed in end view, as in Fig. 2. Such an element can provide in a packed tower or heat recovery chamber, when a great number of such elements are used, up to 92 ft2 of surface area, per cubic foot of elements through which fluids traverse.

It will be seen that the ability to provide enhanced surface areas provides, in the case of chemical tower packings, greater scrubbing possibilities from the greater surface area, and in the case of heat recovery elements, greater heat recovery.

The configurations for the elements as described herein provide for increased scrubbing or heat transfer, as the case may be,. by utilizing smaller passageways which increase the area of the boundary layers, increase the turbulence of fluid passing therethrough, and allow 14 f or more contact with the surface areas. In the case of heat transfer elements, this allows for increased heat transfer.

In accordance with the present invention, it has been f ound that a bed of such elements can provide the same heat transfer at about 37% of a prior art volume of elements, with a 10-15% reduction in pressure drop across the elements. It has also been found that, in accordance with elements of the present invention, for approximately the same pressure drop across a bed of elements, and with the same heat transfer capabilities, only about half the volume of elements is necessary. This allows for considerably less expense in providing elements where existing parameters are acceptable.

While it will also be seen that there can be variations in the radial portions of the "T" configurations, and that depending upon the desired strength of the elements. generally acceptable design criteria can be met. For example,one design criteria is that the elements, when in a bed, should be able to support a column height of up to 50 feet without elements at the bottom of the column being crushed by the weight of elements. Another design criteria is that wall thickness considerations should recognize that elements anywhere in a bed should be capable of supporting up to A 1 2,000 lbs. per ft2 of floor area for the bed. It will be seen that, within the scope of the present invention, flexibility is afforded to allow for different element strengths, depending upon the desired construction parameters.

The materials of construction of the elements may include various metals and non-metals, including ceramics, aluminium, silicon, even plastics, with or without fiberglas imbedments or the like. Generally, the materials of composition will be based upon the desired end use. For example, in high temperature conditions, such as in heat recovery conditions in accordance with the embodiment of use of elements as shown in Fig. 9, it may be desirable that the elements be of ceramic, clay construction or the like, capable of withstanding temperatures of up to 2, 200OF or more. In such cases, the elements may be of stoneware-like construction. In other uses, such as for packed towers, elements of metal construction, such as steel, may be desirable, where temperatures on the order of 5001F may be encountered. It will thus be apparent that any of the various compositions set forth herein, and others not specifically disclosed herein, may be used, all within the term "mineral composition" as set forth in the claims. Such materials may further include porcelain, chemical stoneware, various steels, alloys, hardened 16 metals such as titanium, nickel, teflons, poly- propylenes, or the like. The particular compositions and/or formulations will depend upon the desired end use. Examples of such uses could be in distillation, gas absorption, heat recovery and many related operations. In connection with heat recovery, particularly of the regenerative type, the elements provide skeletons to facilitate the heat recovery as gases pass through the interstices between the individual elements, such that gas streams become f inely divided as gases pass over the elements, allowing heat transfer between the gas and the element.

The present invention seeks to optimize the physical attributes of the elements to provide a maximum surf ace area to mass ratio, in order to optimize the heat transfer rates. It does so by introducing a high state of turbulence, with a minimum pressure drop through the bed of elements, to bring about the enhanced heat transfer performance.

The present invention also provides capabilities to configure the length to diameter ratios of the elements in order to provide a desired orientation during random dumping. Thus, a longer length to diameter dimension will have a tendency to orient the element, when dumped, into a horizontal position to allow for maximum orientation in t 1 1 17 the horizontal direction. The opposite condition will occur with a larger diameter than length, such that there will be a tendency for the element to orient in a vertical position, which will maximize flow in a vertical direction. In this manner, elements can be specifically provided with desired length to diameter ratios depending upon whether flow will be either horizontal or vertical, through the element bed, thereby to maximize the heat transfer efficiency and minimize pressure drops during flow through the bed.

With reference to Fig. 10, it will be seen that there is provided a graph indicating the relative surface to weight rates for various lengths and diameters. For example, following in a vertical upward direction, the various entries for a 0.75 inch diameter element, various surface/weight ratios are presented, ranging from about 1.22 to 1.33, as the length of the element decreases from 2 inches to 1.75 inches, to 1.5 inches, to 1. 25 inches, to 1 inch, to 0.75 inches. Thus, the relative effect of element diameter to element length can be noted, while noting that the cross-sectional configuration produces high surface/weight ratios, irrespective of relative diameter to length ratios, with such surface to weight ratios in all of the graphed instances being between 1.20 and 1.56, as measured in square feet per pound.

18 It will be apparent from the foregoing that various modifications may be made in the details of construction, as well as in use of the elements of the present invention, all within the spirit and purview of the invention as defined in the appended claims.

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Claims (14)

1. An element for use as a heat transfer or chemical tower packing material in which a plurality of the elements are to be disposed in a chamber, to have a fluid passing through the chamber in contact with the elements, said element comprising a one-piece, threedimensional solid shape of mineral composition, constructed of a longitudinally extending core portion having a plurality of similarly configured radial portions extending generally radially outwardly therefrom and terminating in associated periphery portions; each said radial portion and its associated periphery portion being of generally "V shaped crosssection, longitudinally co-extensive of said core portion; with the radial outer-most surfaces of all said periphery portions together defining a generally cylindrical configuration.

2. The element of Claim 1, wherein adjacent ones of said periphery portions are spaced apart from each other, defining longitudinal by disposed channels therebetween.

3. The element of Claim 1, wherein said periphery portions are of generally arcuate cross-section.

4. The element of Claim 1, wherein said core portion has a generally central through-hole longitudinally coextensive thereof.

5. The element of Claim 1, wherein adjacent ones of said periphery portions are spaced apart from each other, defining longitudinal by disposed channels there between, wherein said periphery portions are of generally arcuate cross-section, and wherein said core portion has a generally central through-hole longitudinally coextensive thereof.

6. The element of any of Claims 1-5, wherein the mineral composition thereof includes materials selected from the group consisting of clay, alumina, zinc and other metals.

7. An element for use as a heat transfer or chemical tower packing material in which a plurality of the elements are to be disposed in a chamber, to have fluid passing through the chamber and in contact with the elements, said element comprising a one-piece threedimensional solid shape of mineral composition, and being constructed of generally cylindrical configuration having I A 0 21 openings extending longitudinally thereof, with said element having a surface/weight ratio in square feet/pounds within the range of about 1.20 to about 1.56.

8. The element of Claim 7, wherein the surf ace/weight ratio is within the range of about 1.4 to about 1.5.

9. The element of Claim 7, wherein, in cross-section, the generally cylindrical configuration of the element is about 65% open.

10. The element of Claim 7, wherein the surface/weight ratio is within the range of about 1.4 to about 1.5, and wherein, in cross-section, the generally configuration of the element is about 65% open.

11. The element of any of Claim 1-5, wherein the element has a surface/weight ratio in square feet/pounds within the range of about 1.20 to about 1.56.

12. The element of Claim 11, wherein the surface/weight ratio is within the range of about 1.4 to about 1.5.

13. The element of Claim 11, wherein, in cross-section, the generally cylindrical configuration of the element is about 65% open.

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14. An element for use as a heat transfer or chemical tower packing material, substantially as herein described with reference to Figs 1 to 3 or any one of Figs 4 to 8.

i Published 1990 at The Patent OffIce, State House. 86.11 High Holborn. LondonWClR4TP.Further copies m8Ybe obtainedfrom ThePatentoffice Sales Branch, St Mary Cray, Orpington, Kent BR5 3RD. Printed bY Multiplex techniques ltd, St MaTY CraY, Kent. Con. 1187