US3651862A

US3651862A - Mechanical heat exchanging apparatus

Info

Publication number: US3651862A
Application number: US825090*A
Authority: US
Inventors: Robert G Ballinger
Original assignee: Individual
Current assignee: Individual
Priority date: 1969-04-11
Filing date: 1969-04-11
Publication date: 1972-03-28
Anticipated expiration: 1989-03-28

Abstract

Apparatus for cooling a stream of gas having a temperature of about 2,000* F. by mechanical means. An endless metal curtain of simple construction moves at relatively high speed over and between pulley means transverse of the gas stream, and extends into a cooling enclosure. Stretching means are provided to keep the metal curtain under substantially constant tension at any possible temperature encountered, and purging means are provided to insure that the metal curtain is cleaned without contaminating the coolant. I prefer that the pulley means be driven by a variable speed power means which is controlled by a temperature sensing device positioned in the gas downstream so that the gas stream from the apparatus is cooled to a substantially constant temperature.

Description

1451 Mar. 28, 1972 [54] MECHANICAL HEAT EXCHANGING APPARATUS [72] Inventor: Robert G. Ballinger, 604 Browns Lane,

Ross Township, Allegheny County, Pa. 15237 [58] Field of Search ..165/5, 6, 10, 7, 60; 55/354;

[56] v References Cited UNITED STATES PATENTS 3,211,213 10/1963 Baxley et a1. ..l65/9 2,866,624 12/1958 Holmquist 1 65/6 489,651 1/1893 Karlsteen ..107/57 866,115 9/1907 Dock ..261/80 1,818,391 8/1931 Greene ..261/80X 1,832,374 11/1931 Forby et al ..107/57 X 2,836,398 5/1958 Linderoth ..165/5 FOREIGN PATENTS 0R APPLICATIONS 89,244 8/1922 Austria 165/6 1,062,263 7/1959 Germany .165/6 1,124,528 3/1962 Germany 165/6 693,048 6/ 1953 Great Britain... .165/6 554,507 1/1957 ltaly ...165/6 251,895 5/1926 Great Britain 165/6 Primary Examiner-Albert W. Davis, Jr. Attorney-Buell, Blenko & Ziesenheim [57] ABSTRACT Apparatus for cooling a stream of gas having a temperature of about 2,000 F by mechanical means. An endless metal curtain of simple construction moves at relatively high speed over and between pulley means transverse of the gas stream, and extends into a cooling enclosure. Stretching means are provided to keep the metal curtain under substantially constant tension at any possible temperature encountered, and purging means are provided to insure that the metal curtain is cleaned without contaminating the coolant. I prefer that the pulley means be driven by a variable speed power means which is controlled by a temperature sensing device positioned in the gas downstream so that the gas stream from the apparatus is cooled to a substantially constant temperature.

2 Claims, 6 Drawing Figures PATENTEnmzs 1922 SHEET 1 OF 3 PATENTEnmzs I972 3,651,862

SHEET 2 UF 3 INVENTOR Robert G. Ballinger PATENTEBMAR28 I972 SHEET 3 [1F 3 A .m F

INVENTOR Robert G. Bollinger MECHANICAL HEAT EXCHANGING APPARATUS This application is a continuation-in-part of patent application, Ser. No. 782,130, filed December 9, 1968.

This invention relates to a mechanical heat exchanging apparatus used to cool a stream of gas. It is particularly useful for efficiently cooling a gas stream of very high temperature to a substantially constant temperature without contaminating the coolant.

The use of apparatus to cool a stream of fluid mechanically is broadly old and well known. It provides a compact and relatively inexpensive means of cooling fluid streams such as gases encountered in industrial plants. Such apparatus usually consisted of continuously moving panels of screen-like material sequentially through a hot gas stream and a cold gas or liquid stream. For example, a wheel having continuous radial-shaped sections of screen-like material was positioned transverse of a hot gas stream and a cold gas stream so that for each revolution, each radial shaped section passed successively through the hot gas stream and the cold gas stream. Or, a belt of spring wire moved over and between two pulleys positioned transverse of a hot gas stream and a cold gas stream so that for each revolution of the belt,'a given point thereon passed successively through the hot gas stream and the cold gas stream. Such mechanical heat exchangers were contemplated for use in cooling a fluid stream with a temperature of about 300 F. They were impractical for cooling a fluid stream of very high temperature, such as encountered in certain exhaust systems, because the panel of screen-like material (i) would bind or slip on the pulley means, (ii) would distort until it was incapable of allowing the passage of the gas stream, and/or (iii) could not be moved at high speed.

Mechanical apparatus were not heretofore used to cool gases of such high temperature. To cool such gases one of three methods were ordinarily used: (i) mixing the high temperature gas with ambient air; (ii) conducting the gas through an extended system of metal ducts which are surrounded by ambient air or other coolant, or (iii) conducting the gas through a cold water. or other coolant spray. Each of these methods has one or more disadvantages which made its commercial use undesirable: (i) mixing the gas with ambient air resulted in. uncontrolled temperatures under certain atmospheric conditions in the downstream gas, and resulted in larger volumes of gas to filter; (ii) conducting the gas through extended metal ducts resulted in uncontrolled temperatures in the downstream gas, and involved large expenditures in fabrication and installation of metal ducts; (iii) spraying with water and the like produced large amounts of contaminated liquid which in turn presented problems in disposal to avoid pollution, and problems in maintenance of the equipment because of corrosion and condensation.

The present invention overcomes these disadvantages and difficulties and makes the use of mechanical heat exchanging apparatus commercially feasible in cooling a high temperature gas stream.

I provide an apparatus for cooling a gas stream of high temperature. An endless metal curtain is positioned transverse a gas stream and is extended into a cooling enclosure. Pulley means are provided substantially out of the gas stream, inside or outside the cooling enclosure, so that they are capable of continuously and sequentially moving said metal curtain transverse of said gas stream and through the cooling enclosure. A stretching means is provided to keep the metal curtain under substantially constant tension as it travels between the pulley means at any possible temperature which may be encountered. And cooling means are provided in the cooling enclosure to transfer the heat from said metal curtain to a coolant.

The metal curtain is made of a material which is stable and inert at high temperatures and with high fluctuations in temperature. I prefer that the metal curtain be made of a high chromium-nickel alloy steel such as Inconel, Incoloy" or stainless. I prefer that the metal curtain be made of round or flat, preferably thin wire of simple construction, such as chainlink fence construction, which will flex but not bend the metal or wear the joints substantially Stretching means 7 are comprised of a movable frame 10 and a movable pulley housing 11, which support pulley means 6 positioned below the cooling enclosure 4. Movable when the curtain is moved by the pulley means at relatively high speed. I prefer that the wire size be in the range of from 0.01 inch to 0.25 inch in diameter, but larger diameter wire can be used, particularly when used in a laminate as hereinafter described. In this way, the metal curtain can have an extremely large surface area per unit volume, and yet have a relatively open mesh and in addition tend not to collect contaminates in the gas stream.

The metal curtain need not be made of a highly efficient heat transfer material because of the high temperatures of the gas stream, high speed at which the metal curtain is moved, and the large area per unit volume exposed to the gas stream. Indeed, I have calculated that a steel wire 0.125 inch in diameter can be heated from 200 to l,300 F in 4 seconds when exposed to an air stream of 1,800" F. If additional mass of metal curtain is necessary, heavier wire can be used or, preferably the endless metal curtain can be made of multi-layers of wire. In this connection, I prefer that endless metal curtain be made of multi-layers of wire with larger diameter, larger mesh wire as a base layer so that the useful life of endless metal curtain can be increased without effecting its heat transfer efficiency.

The cooling means for transferring heat from the metal curtain to a coolant may be of any suitable kind. For example, it may consist of a fan or fans which force a stream of cool gas, such as ambient air, through the cooling enclosure. Or it may consist of nozzles that spray water (or other suitable liquid which will not evaporate during the cooling operation) over the metal curtain as it passes through the cooling enclosure. ln either case, the heated uncontaminated coolant could be used to heat a building'or the like.

I prefer that a purge means is provided between the gas stream and the cooling enclosure to clean the metal curtain of any contaminates and thereby insure that the coolant is not contaminated. Such a purge means could be simply a rotary brush placed in contact with the metal curtain. But I prefer that the purge means consist of a high velocity stream of ambient air which is jetted through the metal curtain and into the gas upstream of the metal curtain. l contemplate that the gas stream will be under a negative pressure so that the high velocity stream of ambient air, containing the small amount of contaminates removed from the metal curtain, will be sucked into the gas stream and ultimately to a filtering system. In this way, the metal curtain is cleaned of the small amount of contaminates collected and the coolant safe guarded against contamination.

I further contemplated that my invention can cool gases moving at high velocity, e.g., between 2,000 to 3,000 feet per minute, with a gas coolant moving at the same high velocity. I also contemplated that my invention can be positioned at various orientation relative to gravity and still operate efficiently.

I contemplate that my inventioncan be used to reduce the temperature of exhaust gases of high temperature such as those coming from electric and open hearth furnaces and converters used in the reduction of metals. Such exhaust gases usually contain dust, dirt, oxides and/or various other contaminating material from reduction of scrap, pig iron and the like, and must be cleaned to avoid pollution before the exhaust gases are emitted to the open air. Such exhaust gases, however, leave an electric furnace at a temperature in the range of from 1,500 to 3,000 F. and must therefore be cooled before they can be cleaned. Such exhaust gases have heretofore been cleaned by bag collectors, scrubbers and cyclone separators which require a substantially constant temperature for efiicient operation. As explained hereinbefore, the necessary cooling apparatus heretofore available was expensive to fabricate and operate, and/or resulted in expensive and inefiicient cleaning of such exhaust gases.

My heat exchanging apparatus will cool such exhaust gases to a substantially constant temperature at which the cleaning apparatus can be operated efficiently without capturing contaminates entrained in the gas stream and in turn contaminating a coolant.

I prefer that the pulley means be driven by a variable speed power means and that the power means be controlled by a temperature sensing device positioned in the gas downstream of the metal curtain. By this arrangement, the gas stream can be cooled to a substantially constant temperature by my in vention.

Other details, objects and advantages of my present invention become apparent as the following description of the presently preferred embodiments thereof proceeds.

In the accompanying drawings I illustrate presently preferred embodiments of my invention in which:

FIG. 1 is a cross-sectional side view of an apparatus for cooling a gas stream of high temperature;

FIG. 2 is an end view of an apparatus for cooling a gas stream of high temperature taken along the line lI-II of FIG.

FIG. 3 is a partial side view with portions broken away of an alternative apparatus for cooling a gas stream of hightemperature;

FIG. 4 is a partial transverse view of an alternative apparatus for cooling a gas stream of high temperature taken along the line IVIV of FIG. 3;

FIG. 5 is an enlarged perspective view of an alternative endless metal curtain for apparatus for cooling a gas stream of high temperature as shown in FIG. I and FIG. 3; and

FIG. 6 is an enlarged perspective view of a second altemative endless metal curtain for apparatus for cooling a gas stream of high temperature as shown in FIG. 1 and FIG. 3.

Referring specifically to the drawings, an apparatus for cooling a gas stream of high temperature is comprised of an endless metal curtain 2 positioned transverse of a gas stream 3 within a conduit means 5 and transverse of a cooling enclosure 4. Pulley means 6, is provided above the conduit means 5, and pulley means 6 is provided below the cooling enclosure 4. Such pulley means 6, and 6, are capable of continuously and sequentially moving said endless metal curtain 2 transverse of the said gas stream 3 and transverse of the cooling enclosure 4. A stretching means 7 is provided to keep the metal curtain 2 under substantially constant tension as it travels between the pulley means 6, and 6,, at any possible temperature which may be encountered. And cooling means 8 are provided in the cooling enclosure 4 to transfer the heat from the endless metal curtain 2 to a coolant 9.

The endless metal curtain 2 is made of relatively open mesh round wire 2a of very simple construction of patterns (as shown in FIG. 5) so that it can flex easily and yet not bend the wire or wear substantially the joints 32 of the wire 2a when the metal curtain 2 is driven at speeds of about 50 feet/min. The endless metal curtain can be guided by any suitable means, but preferably flange means 34 (shown on FIG. 3 and FIG. 4) are provided toguide the endless metal curtain 2 or 2'.

In alternative embodiments, the endless metal curtain 2 can be of open mesh flat wire 2b (as shown in FIG. 6) with the largest flat surfaces 33 of the wire 2b substantially in the direction of the stream of gas; in addition, the endless metal curtain 2, whether of round wire 2a of flat wire 2b, can be made of multi-layers (as shown in FIG. 5) where the layer 28 forming the base layer has a larger diameter and mesh than the diameter-and mesh of the wire 29 as an over layer. The endless metal curtain 2 need not have a high specific heat to be efficient because of the high temperatures of the gas stream 3, the high surface area per unit volume of the metal curtain 2, and the high speed of the metal curtain 2. It is made, however, of high chromium-nickel alloy steel, such as Inconel," Incoloy or stainless, which is able to withstand temperatures of about I ,500 F. or about 2,500 F. (depending on the application) and high fluctuations in temperature, and yet remain inert and stable.

The making of the metal curtain 2 in a plurality of layers greatly increases the efficiency of the apparatus. The use of a plurality of layers allows the introduction of heat transfer mass into the gas stream 3 without appreciable increase in the time required to heat the mass. And additional layers can be added without impeding the flexibility of the apparatus because the overlayers can be loosely attached to the base layer without interfering with the operation of the self-adjusting stretching means 7 for keeping substantially constant tension on said metal curtain 2. The use of plural layers of metal curtain 2 also can increase the heat transfer mass without appreciable increase in pressure drop in gas stream 3 across the metal curtain 2, and without appreciable increase in the pick-up of dirt and the like or decreasing the removability of dirt and the like. The cleanability, heat transfer, and pressure drop can be optimized by varying the number of layers of metal curtain 2, the speed of the metal curtain 2, the cross section area and mesh of wire used for various layers of the metal curtain 2 so that the best combination will be present in the particular application.

The cooling means 8 is comprised of simply passing a stream of coolant 9,, (e.g.,,cold ambient air) through the cooling enclosure 4 and through the metal curtain 2. Alternatively and Supplementally, the cooling means may have noule means 18 which spray coolant 9, (e.g., cold water) onto the metal curtain 2 as it passes through the cooling enclosure 4. The nozzle means 18 should be positioned on the outside of the metal curtain 2 on the downstream side so that the water spray contacts the metal curtain as it enters the cooling enclosure 4 and the coolant 9, will tend not to become entrained in the coolant 9,. In addition, by positioning the nozzle means 18 outside of the metal curtain 2 there is less chance that the coolant 9, will become contaminated by removing contaminates from the metal curtain 2. The coolant 9 is collected in movable pulley housing 11 which acts as a sump, and drain means 19 is provided to remove the cold water coolant 9, from the movable pulley housing 11. pulley housing 11 is dimensioned so that it telescopes over metal curtain housing 12 and is provided with a seal of asbestos or the like to form an insulated sliding joint. Movable pulley housing 11 has fixed flange portions 13, and metal curtain housing 12 has fixed flange portions 14, each rigidly fastened to its respective housing 11 or 12. A guided adjustable spring assembly 15, is provided between

flange portions

13 and 14, and is maintained under compression so that the metal curtain 2 is constantly under substantially the same tension at any temperature which may be encountered. In addition, bearing means 27 of pulley means 6 is adjustable so that the metal curtain 2 can be aligned for movement on pulley means 6, and 6,. As an added feature a safety stop 26 is provided on adjustable spring assembly 15; by this arrangement, each safety stop 26 will stop the movable pulley housing 11 from coming apart from the metal curtain housing 12 if the metal curtain 2 should break.

In an alternative embodiment shown in FIG. 3 and FIG. 4, stretching means 7 are comprised of a movable frame 10' and a movable pulley housing 11', which support pulley means 6, positioned below the cooling enclosure 4. Movable pulley housing 11' is dimensioned so that it telescopes over metal curtain housing 12 and is provided with a seal of asbestos or the like to form an insulated sliding joint. Movable pulley housing 11 has fixed flange portions 13', and metal curtain housing 12 has fixed flange portions 14, each rigidly fastened to its respective housing 11 or 12'. Adjustable pneumatic cylinders 30 are provided between flange portions 13 and 14' and are maintained in compression. Adjustable spring assemblies 31 are fastened between flange portions 13' and 14 and are maintained under tension to support the movable pulley housing 11'. In this way, the metal curtain 2 is constantly under substantially the same tension at any temperature which may be encountered, but need not support any substantial portions of the weight of the movable pulley housing 11' whether in operation or not in operation. Supplementally or in the alternative an idler pulley or pulleys (not shown) can also be used in the stretching means 7 to keep substantially constant tension on the metal curtain 2.

The metal curtain 2 is driven by pulley means 6,, positioned below the cooling enclosure 4, which in turn is driven by power means 16. The power means 16 is rigidly fastened to the movable pulley housing 11. Preferably the power means 16 may be a variable speed motor as shown in FIG. 2 or a variable speed gear drive as shown in FIG. 4. By this arrangement, the gas stream 3 can be cooled to a substantially constant temperature by controlling the power means 16 by a temperature sensing device 41. Temperature sensing device 41 has portion 42 positioned in the gas stream 3 downstream of the metal curtain 2 and is electrically connected to power means 16 by lead 43.

In addition, a purge means 20 is provided between the conduit means 5 and the cooling enclosure 4 to clean the metal curtain 2 so that the coolants 9, and 9, are not contaminated with contaminates from the gas stream 3 which may collect on the metal curtain 2. The purge means 20 is comprised of a centrifugal blower 21 which jets a high velocity stream of ambient air through a purge conduit 22 within the metal curtain 2, through the metal curtain 2 and into the gas stream 3, so that the small amount of contaminates collected on the metal curtain 2 are returned to the gas stream 3. The gas stream 3 is normally under a negative pressure so that highly efficient seals are not needed to keep the contaminates from finding their way into the cooling enclosure 4.

The metal curtain housing 12 will in some cases have to be made of high temperature alloy steel or provided with a water jacket because of the high temperature of gas stream 3. In other applications, the metal curtain housing 12, like the movable pulley housing 11, can be made of ordinary low carbon steel because it is surrounded by ambient air which will keep it cool. Pulley means 6, will also have to be made of high temperature alloy steel because of the temperature of the gas stream 3. But in some cases, pulley means 6, like pulley means 6 may be made of ordinary low carbon steel because it is positioned to be cooled. In certain applications, pulley means 6, is cooled by providing a cooling conduit 23 in the metal curtain housing 11 above the pulley means 6, and positioning a baffle 24 between said pulley means 6, and the gas stream 3 within the metal curtain 2; by this arrangement ambient air is sucked into the gas stream 3 through the cooling conduit 23 around the battle 24 to cool the pulley means 6,.

For easy installation assembly flanges 25 are provided on the metal curtain housing 12 so that the apparatus can be spotwelded or bolted to standard metal ducts of a square or rectangular shape.

While I have shown and described certain present preferred embodiments of my invention, it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied within the scope of the following claims.

I claim:

1. Apparatus for cooling a gas stream of high temperature comprising: an open mesh endless metal curtain for receiving heat from said gas stream positioned substantially transverse to said gas stream and extending into a cooling enclosure, said endless curtain being comprised of a plurality of layers of wire, pulley means for continuously and sequentially moving said metal curtain substantially transverse of said gas stream and into the cooling enclosure and positioned substantially out of said gas stream, self-adjusting stretching means for keeping substantially constant tension on said metal curtain where said metal curtain is subject to said gas stream of high temperatures such as in the range of 1,500 to 3,000 F positioned substantially out of said gas stream, and cooling means for transferring heat from said metal curtain to a coolant.

2. Apparatus for cooling a gas stream of high temperature as claimed in claim 4 wherein: said layer of endless metal curtain forming a base layer has wire of larger cross-section than the cross-section of the wire of a layer of endless metal curtain positioned over said base layer.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,651,862 I Dated March 28, 1972 l f Robert G. Ballinger It is certified that error appears in the above-identified patentand that said Letters Patent are hereby corrected as shown below:

Column 2,

lines

1, 2 and 3, delete "Stretching means 7 are comprised of a movable frame 10 and a movable pulley housing 11, which support pulley means 6 positioned below the cooling enclosure 1. Movable";

7 Column 1, line 32, after '11." insert Stretching means 7 are comprised of a movable frame 10 and a movable pulley housing 11, which support pulley means 6 positioned below the cooling enclosure 4. Movable Signed and sealed this 7th day of November 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents OFlM PO-105O (1069) USCOMM-DC GQB'IB-PBQ U.S, GOVERNMENT PRINTING OFFICE I969 0-356-334,

Claims

1. Apparatus for cooling a gas stream of high temperature comprising: an open mesh endless metal curtain for receiving heat from said gas stream positioned substantially transverse to said gas stream and extending into a cooling enclosure, said endless curtain being comprised of a plurality of layers of wire, pulley means for continuously and sequentially moving said metal curtain substantially transverse of said gas stream and into the cooling enclosure and positioned substantially out of said gas stream, self-adjusting stretching means for keeping substantially constant tension on said metal curtain where said metal curtain is subject to said gas stream of high temperatures such as in the range of 1,500* to 3,000* F., positioned substantially out of said gas stream, and cooling means for transferring heat from said metal curtain to a coolant.