US1988659A - Heat exchange apparatus - Google Patents

Description

Jan. 22, 1935. w. D. LA MONT HEAT EXCHANGE APPARATUS Filed April 23, 1930 WITNESS Q.;f 64

INVENTOR W'qLTER D. LAMONT Patented Jan. 22 1 935 PATENT OFFICE HEAT EXCHANGE APPARATUS Walter Douglas La Mont, North Colebrook, Conn., assignor to La Mont Corporation, New York, N. Y., a corporation of New York Application April 23, 1930, Serial No. 446,546

Renewed June 2, 1934- 20 Claims.

This invention relates to heat exchangers, and more particularly to steam generators of the general type disclosed in my prior Reissue Patent No. 16,895, in which a forced circulation of water is maintained through the generating tubes at a rate in excess of their evaporating capacity.

In apparatus constructed to operate in this manner it is essential to distribute the water among the tubes and deliver a sufiicient quantity of water to each individual tube, for if the water supply to a particular tube should fail, it would almost immediately be damaged by the heat. In my prior construction I provided an orifice at the entrance end of each tube to control the quantity of water flowing thereto.- These orifices may be .sufliciently large to permit the delivery of the necessary water under normal conditions, but I have discovered that there is serious danger of the orifices becoming obstructed during operation by foreign material, such as pipe scale, in the water. This has either caused damage to certain of the steam generating tubes or necessitated the shutting down of the entire steam generator to permit the removal of the foreignmaterial. Many prior attempts have been made to overcome this difiiculty,. but none have proven satisfactory so far as I am aware.

It is accordingly the main object of my invention to provide a steam generator having orifices at the entrance ends of the steam generating tubes, in which means is provided to effectively protect the orifices against pluggin by foreign material and to ensure an adequate supply of waterfor each tube at all times. i

It is a further object of my invention to provide an individual screen for each orifice of a steam generator, the construction being so arranged that the screens may be easily and effectively cleaned without shutting down the generator.

A further object is to provide means for reversing the direction of flow through the individual orifice screens and thereby remove any. foreign material collected thereon.

A further object is to provide means to prevent 45 foreign material in the generating tubes from plugging the orifices when the direction of flow is reversed.

A further object is to provide an individual screened nozzle which is arranged'to be mounted so at the entrance end of a steam generating tube to supply water thereto, and which is free from danger of clog ing. I With these and other objects in view, as will be apparent to those skilled in the art, my invention 55 resides in the combination of parts set forth in the specification and covered by the claims appended hereto.

In accordance with.one embodiment of my.

invention I provide a steam generator'having steam generating tubes to which water is delivered by a suitable forcing means, such as a pump. A flow restricting orifice is located at the entrance end of each tube, and each orifice is protected by an individual screen mounted close to the orifice and on the inlet side thereof. Each screen is preferably shaped as a hollow cylindrical sleeve of non-corrosive metal having perforacharge side thereof to prevent scale from reaching the orifice during this cleaning operation.

Referring to the drawing illustrating one embodiment of the invention, and in which like reference numerals indicate like parts,

. Fig. 1 is a vertical sectional elevation of a steam generator;

Fig. 2 is an enlarged cross section through the inlet header, the section being taken onthe line 2-2 of Fig. 1;

Fig. 3 is a perspective view of the orifice member;

Fig. 4 is a perspective view of the screen for the discharge side of the orifice; and

Fig. 5 is a perspective view'of the sleeve which change apparatus. The embodiment illustrated I comprises a furnace chamber 10 which is maintained at a high temperature by any suitable means. For this purpose I have shown an oil burner 11 arranged to deliver oil for combustion in the furnace in a well known manner.

A boiler 12 of any desired type is mounted above the furnace to absorb heat therefrom by radiation and convection. For simplicity of ii- I lustration, this boiler 12 has been shown as a horizontal cylindrical drum forming a receptacle for steam and water under pressure. Water may be supplied to the drum 12 from any suitable source through a feed pipe 14, and steam may be withdrawn from the drum through a pipe 15 leading to a main steam header 16.

Adjacent to one wall of the furnace chamber 10 I have shown a water wall comprising spaced parallel horizontal tubes 18 arranged to generate steam by the absorption of radiant heat from the furnace and to protect the refractory material of the wall behind them. The tubes 18 are connected at one end to a vertical pipe or inlet header 19, and at their opposite ends to a vertical outlet header 20. A suitable forcing means, such as a centrifugal pump 22 driven by an electric motor 23, is provided to circulate water through the tubes. A pipe 24 is connected to the drum 12 below the water line and leads to the inlet of thepump 22. The discharge of the pump is connected to the inlet header 19 of the water wall. The outlet header 20 is connected by means of a pipe 26 with the steam space of the drum 12. With this construction the pump 22 draws water from the drum 12 through pipe 24 and delivers it under pressure to inlet header 19 and tubes 18. Thesteam which is formed in the tubes, together with any unevaporated water, passes back to the drum 12 through header 20 and pipe 26.

In order to insure a sufiicient pressure drop between the inlet header and the tubes and thus obtain proper distribution of the water among the several tubes and prevent the steam formed in the tubes from flowing back into the inlet header, it is necessary to provide means, such as orifices, for restricting the cross sectional area available for flow at the entrance end of each tube. The present invention is concerned with the construction of these orifices and with means for maintaining them in proper operating condition and for preventing the operation from being affected by the presence of foreign material in the water. Y

In the preferred embodiment illustrated the header 19 is provided with a cylindrical opening 2'7 for each tube 18, and each of these openings has an annular groove 28 therein. The tubes are rolled into the openings 2'7 and the metal is expanded into the groove 28 in a well known manner by inserting an expanding tool through a second opening 30 provided in the wall of the header directly opposite each tube. This opening 30 is preferably screw threaded and closed by a suitable plug 31. An annular gasket 32 is placed beneath a shoulder 33 on each plug and serves to prevent leakage of the water from the header.

Atthe entrance end of each tube 18 I provide a hollow cylindrical sleeve 35 having an external diameter substantially equal to the internal diameter of the rolled portion of the tube. This sleeve is inserted into the tube coaxially therewith and fits tightly enough to prevent leakage between these parts. In some cases it may be dewhich fits tightly in the interior of the sleeve 35. This construction is preferable to an integral one, since it permits the sleeve 35 to be made from commercial tubing and avoids considerable machining. The face of the member 39 surrounding the entrance end of the orifice 37 is beveled as shown at 40 so as to slope toward the orifice. This avoids sharp internal corners in which accretions of scale might form. The member 39 may be held in the sleeve 35 in various ways, but I prefer to contract the diameter of the sleeve slightly at each side of the member by. rolling circumferential grooves 41 in the external surface of the sleeve. This construction provides an individual screened nozzle insertable as a unit in the entrance end of the tube for supplying water thereto.

In order to prevent the entrance of foreign material into the interior of the sleeve through the open end thereof, I provide means for at least partially closing this end. This I preferably accomplish by providing a cylindrical member or rod 43 supported by the plug 31 and extending coaxially therewith into the sleeve 35. This rod 43 is preferably slightly smaller in diameter than the interior of the sleeve, for reasons which will hereinafter appear, but this difference in diamever is, however, less than the diameter of the orifice 37, so that even though the parts should become out. of alignment and the rod should contact with the interior of the sleeve at one side, nevertheless the space between these parts on the opposite side would be insufiicient to permit the passage of foreign particleslarge enough to obstruct the orifice.

The wall of the sleeve 35 is provided with a plurality of openings or perforations 44 therethrough, each preferably circular in shape'and of foreign particles which might cause plugging thereof.

Such foreign particles, however, are likely to obstruct the openings in the screen after a considerable period of operation, and there is also a possibility of chemical deposits from the water occurring in the interior of the sleeve 35. I therefore provide for thoroughly cleaning the orifice and screen without interfering. with the operation of the furnace, and I obtain this result by reversing the direction of flow through these parts. For this purpose I provide a blow off pipe 50 leading from the inlet header 19 and having a valve 51 therein, and I also provide means, such as a valve 52 at the discharge of the pump 22, for cutting off the supply of water from the boiler 12 to the header 19 during the cleaning periods. By closing valve 52 and opening valve 51, the operator can cause steam from the drum 12 to flow under full boiler pressure through pipe 26, header 20, and tubes 18, through the orifices and screens in 'a reverse direction, and out through blow off pipe 50 to a suitable place of deposit. This steam will not only flow outwardly through the openings 44 in the screen, but it will also flow along the interior surface of the screen and out through the annular space between the sleeve 35 and the rod 43. It is thus possible to blow out through this annular space flakes of scale or chemical deposits which may have formed inside the screen and which cannot pass through force the sleeve 35 out of the tube 18 when the copending application for Letters Patent Se'rial flow is reversed for cleaning purposes. In order to prevent this from happening, I provide a pin 55 extending transversely of the rod 43 and closely adjacent to the end of the sleeve. The pin 55 may be made a drive fit in an opening in the rod, and serves to retain the sleeve in its proper position.

The steam flowing along the tubes 18 toward the orifices may pick up scale or other foreign material and force it into the orifices, thereby bringing about the very difiiculties' which the screen 35 is intended to prevent. I therefore provide a second screen 56 to protect each orifice from this possibility.- Each screen 56 is shaped as a fiat thin circular disk having circular openings 58 therethrough slightly smaller in diameter than the orifice 37. The disk 56 is preferably of the same diameter as the orifice plug 39 and fits closely against the discharge side thereof within the sleeve 35. These parts are all held in an assembled relationship by the rolling of the grooves 41. The orifice plug is shown in Fig. 2 as provided with a beveled or countersunk face on its discharge side similar to the beveled face 40 on its inlet side, so that the screen 56 is spaced from the orifice and the screen openings are unobstructed by the plug. The parts 35, 39 and 56 are preferably made of some non-corrosive material, such as Monel metal. l

The operation of the inventionwill be apparent from the above disclosure. The pump 22 delivers water to the inlet header 19 at a pressure in excess of the boiler pressure, and this water is distributed to the tubes by the orifices 37, the steam and any excess water flowing tothe boiler through pipe 26. The screens 35 prevent any clogging of the orifices by foreignmaterial in the water, and any such material which does accumulate on the outside of the screens, as well as any scale which may form inside thescreens, may be easily removed during the operation of the boiler by manipulating the valves 51 and 52 to reverse the direction of fiow. The construction is simple and inexpensive to manufacture and install, and thoroughly reliable in operation.

This application is a continuation in part of my No. 140,665, filed October 9, 1926 Having. thus described my invention, what I claim as new and desire to secure by Letters Patent is: l v

'1. A heat exchange apparatus comprising a plurality of tubes, means for delivering fluid into one end of each tube and causing it to flow therethrough in ,heat exchanging contact therewith, means restricting the cross sectional area at the entrance end of each tube for limiting the flow of the fiuid into the tube, and means for reversing the direction of fiow of the fluid being heated arranged in such relation to said restricting means that said reverse flow of the fluid within the heat exchanger is distributed by said restricting means so that said'reverse flow is caused simultaneously through all said restricting means whereby foreign material is simultaneously removed therefrom. 1

2. Steam generator comprising a plurality of stea'n generating tubes each having one of its ends connected to a header, means to supply water under pressure to said header for delivery into the tubes and flow therethrough, a receptacle for steam under pressure, connections between the other ends of said tubes and the steam receptacle normally to deliver thereto the steam generated in the tubes, means forming a restricting orifice at the water inlet end of each tube, a blow-off pipe connected to the header, and valve means for reducing the pressure of the water in the header and opening the blow-off pipe, the arrangement of said valve means and said blow-oil relative to the header and to the orifices being such that steam from the receptacle is distributed by said orifices so as to be caused to flow along each tube and through each orifice simultaneously in areverse direction and to create a reverse pressure drop through the orifices, said orifices acting to maintain within the tube a pressure not substantially diiferent from that within the receptacle, said reverse fiow and pressure drop thus acting to remove accumulations of foreign material in the orifices.

3. A heat exchange apparatus comprising a tube, means to supply liquid to one end thereof, a hollow cylindrical sleeve fitted endwise to said end of the tube, and means adjacent the end of the sleeve which is fitted to the tube and formed to provide a restricting orifice inside the sleeve through which-the liquid entering the tube must the inlet end of each tube, a hollow cylindrical.

sleeve mounted adjacent to each orifice and coaxial with the corresponding tube, said sleeve having openings in its walls, and a cylindrical member mounted within the sleeve, said cylindrical member being smaller in diameter than the interior of the sleeve so as to form an annular passage between the member and the sleeve, and meansto reverse the direction of flow through the orifice and the annular passage while the generator is in operation.

5. A steam generator as recited in claim 4 in which each cylindrical member is supported on a plug which is mounted in an opening in the wall of the header directly opposite to the inlet end of the tube.

6. A steam generator as, recited in claim 4 in which the end of the cylindrical member toward the tube is shaped as a conical point to guide foreign material into the annular passage when the flow is reversed. 7. A steam generator comprising an inlet header, means to supply water under pressure to the header, a. plurality of steam generating tubes having their inlet ends connected to the header,

a thin walled hollow cylindrical sleeve inserted in f the inlet end of each tube, a cylindrical body fitted tightly in the inside of the sleeve and having a circular fiow restricting orifice therein, the sleeve being provided with circular openings in its walls anterior tothe orifice and smaller in diameter than the orifice, a fiat circular disk mounted within the sleeve adjacent to the discharge side of the cylindrical body and having a plurality of circular openings therethrough each smaller in diameter than the orifice, the sleeve having a circumferential groove rolled in its external surface anterior to the cylindrical body and a similar groove posterior to the disk to hold these parts in position, and means to reverse the direction of flow through the orifices while the generator is in operation.

8. A steam generator comprising an inlet header, means to supply water under pressure to the header, a plurality of steam generating tubes having their inlet ends connected to the header, means forming a fiow restricting orifice at the entrance end of each tube, a separate cylindrical screen at the entrance side of each orifice, a plug mounted in an opening in the wall of the header opposite to the inlet end of each tube, and means supported by each plug for holding the corresponding screen in its proper position.

9. As an article of manufacture, a fluid supply nozzle for use with a tube of a heat exchange apparatus comprising a thin walled hollow cylindrical sleeve formed at one end thereof so as to be fitted tightly to the fluid inlet end of the tube, and a cylindrical body fitted tightly in the inside of the sleeve, said body having an orifice opening therein communicating from inside the sleeve to the tube when the sleeve is fitted to the tube, said sleeve being provided with openings in its walls anterior to the orifice relative to the flow of fluid therethrough and being so constructed and arranged that fluid flowing into the tube through the orifice for the most part must pass through said openings in said walls, said openings having a diametral dimension less than the diametral dimension of the orifice.

10. A nozzle as recited in claim 9 in which the face of the cylindrical body is beveled on the entrance side of the orifice.

11. As an article of manufacture, a fluid supply nozzle for use with a tube in a heat exchange perforated screen carried bythe member and mounted at that side of the orifice which is outside the hollow space of the member.

12. As an article of manufacture, a fluid supply nozzle for use with a tube of a heat exchange apparatus comprising a hollowsleeve of a form to be fitted to the inlet end of the tube, a body fitted tightly in the inside of the sleeve and having an orifice therein communicating from the hollow space of thesleeve to the tube when the sleeve is fitted thereto, said sleeve being provided with openings in its walls anterior to the orifice relative to the flow of fluid therethrough, and a flat perforated screen mounted .at the discharge side of the orifice, the discharge face of said body being beveled.

13. As an article of manufacture, a nozzle for a heat exchange apparatus having a heat exchanging tube comprising a hollow cylindrical sleeve of aform to be fitted to the tube at the fluid supply end of the tube, and a cylindrical body fitting within said sleeve and having an orifice for limiting the flow of fluid into the tube, said sleeve being constructed at an end thereof remote from said cylindrical body to provide at most a revapor generating tubes, means for supplying to said tubes at one end of each tube the liquid to be vaporized in quantity sufficient for the evaporation in said tubes, means connected to the other ends of the tubes for receiving the fluids discharged therefrom, means at the inlet end of each tube for restricting the flow of the liquid into each tube while permitting its passage into the tube in quantity suflicient for the evaporation in said tube, and means for causing fluid from said fluid receiving means to flow by way of said tubes reversely through said flow restricting means to removetherefrom foreign material, said means for reversing the flow being so arranged in relation to said restricting means that said restricting means act to limit the flow from said receiving means reversely through each tube and to distribute said reverse flow so that said reverse flow is produced simultaneously through all said restricting means.

15. A steam generator comprising a plurality of steam generating tubes, means for positively delivering to one end of each of said tubes under pressure greater than that existing in the tubes water in quantity greater than can be evaporated in passage of the water through the tubes, means at the water inlet end of each tube providing an orifice for maintaining a pressure drop while limiting the water entering the tube to a quantity insufiicient to fill the internal cross sectional area of said tube, means connected to the discharge end of the tubes for collecting the steam and water discharged from the tubes, and means for causing the steam and any water carried'therewith from said collecting means to flow in reverse direction through the tubes and arranged in relation to said orifices so that said reverse fiow is distributed by said orifices simultaneously to flow reversely therethrough under a reverse pressure drop and to be exhausted from the generator on the water delivery side of said orifices to remove foreign material therefrom.

-16. As an article of manufacture, a fluid supply nozzle for use with a'tube of a heat exchange apparatus comprising a hollow sleeve of a form at one end thereof to fit to the fluid inlet end of the tube, said sleeve being constructed adjacent said end thereof so as to close said hollow sleeve but to provide an orifice opening from the hollow space within the sleeve to the tube when the sleeve is fitted thereto, said sleeve being constructed, at the other end thereof to provide restricted if any opening and being provided with openings in the walls enclosing the hollow space communicating from outside the sleeve to the hollow space within the sleeve for passage of fluid to said space, said. openings being of restricted size in relation to the size of said orifice opening but of sufiicient number to provide for the flow of the fluid to the orifice for passage therethrough into the tube.

17. As an article of manufacture for use with a tube of a heat exchange apparatus, the combination with a fluid supply nozzle in the form of a hollow sleeve having screening openings in the 18. A heat exchange apparatus comprising a.

plurality of tubes arranged for heating a fluid under a selected pressure, means normally acting to deliver fluid into one end of each tube and to cause it to flow therethru in heat exchanging contact therewith, means restricting the cross sectional area at, the entrance end of each tube for limiting the fiow of the fluid into the tube and producing a pressure drop at said end thereof, and means for stopping the normal flow of said fluid and concomitantly reversing the direction of fiow and of the pressure drop thru the restricting means of the fluid being heated, said means being arranged in such relation to said restricting means that said reverse flow of the fluid within the heat exchanger is distributed by said restricting means so that said reverse flow is caused simultaneously through all said restricting means whereby foreign material is simultaneously removed therefrom.

19. A vapor generator comprising a plurality of vapor generating tubes connected in a closed circuit for circulation of the liquid to be evaporated, means in said circuit for causing the liquid to flow therethru and to be delivered to one end of each tube, means at said inlet end of each tube for restricting the flow of the liquid into the tube and providing a pressure drop in said liquid for causing the generated vapor and any liquid in excess of that evaporated to: be discharged from the opposite end of the tube, means for returning to the liquid delivery means any excess liquid so discharged from the tube, means for stopping the creation of the pressure upon said restricting means of the liquid being delivered to the tube, and means for reducing said pressure below the pressure of the vapor and of any liquid within the tube and so arranged in relation to said restricting means as simultaneously to cause a reverse pressure upon each restricting means and a distributed reverse flow of the vapor and any liquid within the tube thru all said restricting means simultaneously to remove foreign material therefrom.

20. In a steam generator having a plurality of steam generating tubes connected in a closed water circuit having therein a pump for delivery of the water thru said circuit and said tubes, the combination with means providing an orifice at the water inlet end of each tube for limiting the flow of water into said tube and for creating a pressure drop thru the orifice of means for reducing the pressure upon the water delivery side of .said orifices below the pressure of steam and water within the tubes, said means being so arranged in relation to said orifices as simultaneously to reduce said pressure upon all the orifices while maintaining substantially normal pressure in said tubes and in the remainder of the circuit to cause steam and any water carried therewith simultaneously to flow reversely through all the orifices in amount capable of removing foreign material therefrom.

WALTER DOUGLAS LA MONT.

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