US2976856A - Vapor generator - Google Patents

Description

March 28, 1961 R. A. MOCORMACK VAPOR GENERATOR 3 Sheets-Sheet 1 Filed Dec. 12, 1958 ATTORNEY March 28, 1961 R. A. MCCORMACK 2,976,856

VAPOR GENERATOR Filed Dec. 12, 1958 3 Sheets-Sheet 2 "I "I Al? INVENTOR Richard A. McCormock Fig. 2. a y/d ATTORNEY March 28, 1961 R. A. MCCORMACK VAPOR GENERATOR 3 Sheets-Sheet 5 Filed Dec. 12, 1958 INVENTOR Richard A. McCormock 2 14! ATTORNEY VAPOR GENERATOR Richard A. McCormack, Bayside, N.Y., assignor to Combustion Engineering, Inc., New York, N.Y., a corporation of Delaware Filed Dec. 12, 1958, Ser. No. 780,083

4 Claims. (Cl. 122--'4-78) This invention relates generally to vapor generators of large capacity such as those employed in the utility industry and has particular relation to such a generator organized in a manner so that a more eflicient utilization of the furnace may be had and a more uniform heat distribution may be had across the stream of combustion gases passing up through and issuing from the furnace.

In accordance with the invention there is provided an upright furnace into the lower portion of which is intro duced fuel and air with the fuel burning therewithin and the combustion gases passing up through the furnace and out through a lateral passage or opening at the upper end of the rear wall. Extending from this lateral opening is a generally horizontal gas pass which connects with a downwardly extending gas pass and within each of these passes is disposed convection heat exchange surface, generally superheater and reheater surface, in the form of sinuously bent tubes. The rear wall of the furnace immediately below the lateral combustion gas outlet is generally provided with a so-called nose baflle which is to direct the upwardly flowing gases toward the front wall of the furnace to prevent short circuiting of the gases through the lower portion of the lateral outlet and to effect a mixing of the gases as well as to attempt to better utilize the heat exchange surface lining the furnace wall in the upper front portion of the furnace. However, even with this nose bafde .it is found that the heat exchange surface in this location is relatively ineffective because the combustion gases tend to by-pass this zone and also the nose bafile does not mix the gases suificiently to provide a uniform heat distribution across the width of the gas stream.

In order to offset these undesirable effects as well as to provide other advantages thefurnace of this invention is provided with tubular panels spaced across the furnace in the upper front portion thereof with these panels preferably comprising the high temperature or finishing stage of a superheater with the low temperature stage and perhaps an intermediate stage being convection heat exchange surface in the gas passes communicating with the furnace outlet. Immediately to the rear of this superheater section there is provided a tubular wall which extends all the way across the furnace. This wall extends down from the upper end of the furnace immediately behind the superheater panels and at the lower end of the panels, the tubes which make up this wall are .bent laterally so that they extend through the front wall of the furnace in closely spacedrelation with the panels at their lower ends. The laterally extending portion of this wall of tubes as well as the upper portion thereof is provided with openings for the entrance and exit of combustion gases while the intermediate portion of .the -wall is substantially .imperforate. With this arrangement the wall acts as a guide to direct combustion gases into the upper front portion of the furnace whereby greater utilization of the heat exchange surface on the furnace walls at this location is obtained and through this arrangement a more even heat distribution across the gas stream is provided.

nited States I atent O f 2,976,856 Ce Patented .Mar. 28,, 1961 The tubes that make up this wall may form the low temperature portion of the reheater of the vapor generator and these tubes are-effective to shield to an appreciable extent the superheater tubes in the high temperature section of the superheater so that the likelihood of excessive metal temperature in these tubes may be greatly reduced if not eliminated.

Accordingly, it is an object of this invention to provide an improved vapor generator. 7

Other and further objects of the invention will become apparent to those skilled in the art as the description proceeds.

With the aforementioned objects in view, the invention comprises an arrangement, construction and combination of the elements of the inventive organization in such a manner as to attain the results desired as hereinafter more particularly set-forth in the following detailed description of an illustrative embodiment, said embodiment being shown by the accompanying drawing wherein:

Fig. 1 is a diagrammatic representation in the nature of a vertical sectionithrough a vapor generator embodying the present invention; 1 p v Fig. 2'isa detailed representation of the tubular wall located at the upper portion of the furnace and is taken generally from line 22 .of Fig. l; and

Fig. 3 is a perspective view, fragmentary in nature,

showing the disposition of this tubular wall and the. panel heat exchangerlocated in front .of the wall and between the wall and the front of the furnace.

Referring now to the drawing, wherein like reference characters are used throughout to designate like elements, the illustrative and preferred embodiment of the-invention depicted therein is comprised .of an elongated upright furnace 10 which issupplied with fuel andair in its lower region through burners 12 and which has its walls lined with heat exchange surface in the form of tubes 14 which may be steam generating tubes that are connected at their lower ends with one of the headers 1.6 and the upper ends with steam and water drum 18. The furnace has the conventional rectilinear transverse section and thereaf Wall 20 of the furnace is provided with the usual lateral outlet 22 with nose bafile 24 extending inwardly of the furnace immediately below this outlet in order to direct the combustion gases that pass upwardly through the furnace towards the upper front portion thereof and to, at least to a degree, effect a mixing of .these gases. The combustion gases pass from the furnace through outlet 22 and then traverse the generally horizontal gas pass 26 that extends from this outlet and which leads to the vertically disposed gas pass 28 with the combustion gases passing down through this later gas pass to a suitable point .of discharge. 7

In the illustrative organization, steam from steam and water drum 18 is conveyed through conduit 30 to the, primary or low temperature stage 32 of the superheater and which is comprised of a tube bundle formed of sinu ously bent tubes-disposed in gas pass 28. From low tem. perature section 32 the steam passes through conduit 34 to the intermediate stage 36 of the superheater and from this intermediate stage the steam is conveyedthrough conduit 38 to the finish or high temperature stage 40.. This high temperature superheater stage is comprisedxof tubular panels identified as 42 in Figs. 1 and 3 and which are spaced in side by side relation across the width of the furnace, with. two such spaced panels being shown in Fig. 3 and with the space between adjacent panels beingiden tified as 43 (Fig. '3). The tubes that make up thesevv panels are connected at their upper ends to inlet header 44 and at their lower ends with outlet header 46 with these tubes extending down from header 44 through the roof 48 of the furnace and then through the frontfw'all' 50.

Immediately to the rear of these panels 42 that make up the high temperature superheater section is a group of tubes which are effective to form a baffle or directing vane to direct combustion gases into the upper front por-- tion of the furnace and over the panels 42. This wall, identified generally as.52,1is comprised of tubes54 which are connected at their upper ends with header 56 and at their lower ends with header 58. These tubes may make up the initial or primary section of the reheater of the vapor generator with steam that is to be reheated, and which is the superheated steam produced by the generator after a portion of its energy has been utilized, being supplied to header 58 and passing up throughthese tubes to header 56. The Wall 52 extends down from the upper end of the furnace in adjacent relation to the panels 52 and at the lower end of the panels the tubes 54 making up this wall and laterally bent so that they extend through the front wall of the furnace in spaced relation with the lower end of the panels The upper portion of this wall, identified as 60, and the laterally extending portion, identified as 62, are provided with openings or passages 63 (Figs. 2 and 3) in order that gases may pass up in front of this wall and into the area occupied by the panels 42 with arrows 64 indicating the flow of the combustion gases. The intermediate portion of the wall 52, i.e., the portion intermediate the portions identified as 60 and 62 and which is identified as 61 is generally imperforate so that it is effective to direct the combustion gases as indicated. This wall 52 may be made up of tubes which are in tangent relation to each other throughout the imperforate portion of the wall with these tubes being bent so that groups of tubes are disposed one behindthe other in the portions 60 and 62 to define passages 63. This construction of wall 52 is shown in Figs. 2 and 3 wherein the tubes 54 are arranged in groups of four for the purpose of forming the passages 63; The detailed construction of this wall is only illustrative of many constructions that may be employed, as, for example, finned tubes may be employed with the fins omitted at the portions 60 and 62 of the wall so as to form the necessary passages and being arranged to form a generally imperforate wall intermediate these wall portions. It will be understood that the invention includes other and different constructions from that shown for forming the wall 52.

The steam that enters header 56 is conveyed through conduit 66 to and through the high temperature stage 68 of the reheater with this finally reheated steam being then conveyed through conduit 70 to a suitable point of use. i It will be appreciated that wall 52 not only directs combustion gases into the upper front region of the furnace so as to better utilize the heat exchange surface that lines the furnace walls in this region and that may be positioned within this zone of the fm'nace, but also protects the tube panels 42 to an appreciable extent, from the intense radiant heat within the furnace 10. In thedisclosed embodiment of the invention the tubes 54 of wall 52 have relatively low temperature steam that is to be reheated passing through them so that the likelihood of these tubes overheating is not of any great concern. However, the tubes of panels 42 have the highest temperature steam passing through them since these panels form the final or finishing stage of the superheater, Therefore care must be taken in order that the tube metal in this section does not become excessive and the protection afforded by wall 52 is of substantial advantage in this connection.

' In addition to providing a better utilization of the heat-v ing surface in the furnace and in protecting the tubes of panels 42, the wall 52 and this wall together with the panels 42 gives a more uniform heat distribution across the gas stream issuing from outlet 22 and which traverses the convection heat exchange surface therebytending to prevent overheating one section of this surface relative to another.

4 While I have illustrated and described a preferred embodiment of my invention it is to be understood that such is merely illustrative and not restrictive and that variations and modifications may be made therein without departing from the spirit and scope of the invention. 1 therefore do not wish to be limited to the precise details set forth but desire to avail myself of such changes as fall within the purview of my invention.

What is claimed is: l. A vapor generator comprising in combination an elongated upright furnace having an outlet for combustion gases extending laterally through one of its walls adjacent the upper end thereof and being fired with fuel at a location remote from said upper end with the furnace walls being lined with heat exchange tubes, superheating means operative to heat the vapor generated by the vapor generator and comprising a low temperature section in the path of the gases issuing from the furnace and a high temperature section with this latter section being disposed across the upper region of the furnace adjacent the wall opposite said one wall, an inlet header for and connected with this latter section and disposed above said furnace in the region of this section and an outlet header therefor outwardly of said opposite wall at the lower end of the latter superheater section and extending horizontally across the wall, a group of heat exchange tubes disposed across the furnace and forming a portion of the heat exchange surface of the boiler, said group of tubes extending vertically down from the upper end of the furnace in adjacent relation with said high temperature superheater section but between this section and said one wall and being laterally bent at the lower end of this high temperature superheater section to extend therebelow and out said opposite furnace wall, the tubes having their opposite end connected with headers adjacent the headers for the high temperature superheater section, the upper region of this group of tubes and the transversely extending portion thereof being com prised of groups of tubes in spaced relation across the furnace and the portion intermediate these portions being comprised of tangent side by side tubes forming a generally imperforate wall.

2. In a steam generator of the type described an upright elongated furnace fired with fuel in its lower region and having its exit for combustion gas at the upper end of the rear wall, with the furnace wall being lined with heat exchange tubes, means for superheating vapor generated by the vapor generator including a low temperature superheater section and a high temperature superheater section with this latter being comprised of sinuously bent tubular members in the form of panels extending downwardly into the furnace adjacent the front wall thereof and disposed in closely spaced relation across said front wall, an inlet header above the furnace with which the tubes of the panels are connected and an outlet header spaced outwardly of the front wall of the furnace and adjacent the lower ends of the panel and with which the tubes of the panels are connected, a tubular wall extending down into the furnace adjacent the panels and between the panels and the rear furnace wall with the tubular wall being bent toward the front furnace wall so as toextend beneath the tubular panels and pass through the front wall, said tubular wall being an imperforate wall throughout a major portion of its length including the lower portion thereof with the wall being provided with openings at its upper portion and in the portion extending beneath the panels whereby the wall acts as a directing baffle for directing combustion gases through the upper region of the furnace adjacent the front wall and over the panels and at the same time protect the panels to a substantial extent from the radiant heat evolved in the burning of fuel in the lower portion of the furnace. v e

3. A vapor generator comprising an upright furnace of rectangular transverse section having its walls lined 5 with heat exchange tubes and having a lateral exit for combustion gases through the upper end of the rear wall, said furnace being fired in the lower region thereof, a superheater forming part of the vapor generator and including a low temperature section in the path of the combustion gases issuing from the furnace and a high temperature section, said high temperature section comprising vertical panels of heat exchange tubes adjacent to and spaced across the front Wall of the furnace with the panels having their median plane normal to said front Wall, a horizontal header disposed above the furnace in the region of the panels and another horizontal header spaced outwardly of the front wall at the lower end of the panels with opposite ends of the tubes of the panels being connected with these headers, a reheater forming part of the vapor generator and also including a high temperature section in the path of the combustion gases issuing from the furnace and a low temperature section, said low temperature section comprising a wall disposed across the furnace and formed 20 of tubes extending vertically down in the furnace adjacent and to the rear of the panels and transversely beneath the panels and through the front wall, headers connected with these tubes and disposed in similar relation to the headers for the high temperature section, said wall being imperforate throughout its lower extent and being provided with passages in its laterally extending portion for the ingress of said combustion gases and in its upper portion for the egress of said combustion gases.

4. The organization of claim 3 wherein the imperforate portion of the Wall is comprised of tangent vertically disposed tubes Welded together and the portion of the wall having passages therein is comprised of tubes bent to lie one behind another in the direction of combustion gas flow in groups that are spaced across the furnace.

References Cited in the file of this patent UNITED STATES PATENTS

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