US3196843A - Baffle arrangement for vapor generator - Google Patents

Description

y 1965 A. c. u CAUSI 3,196,843

BAFFLE ARRANGEMENT FOR VAPOR GENERATOR Original Filed Sept. 11, 1961 2 Sheets-Sheet l ATTORNEY July 27, 1965 A. c. L]! CAUSI BAFFLE ARRANGEMENT FOR VAPOR GENERATOR 2 Sheets-Sheet 2 Original Filed Sept. 11. 1961 IN VEN T OR.

ANTHONY C LICAUS! A TTORNEY United States Patent 3,196,843 RAFFLE ARRANGEMENT FOR VAPQR GENERATOR Anthony C. Li Causi, East Brunswick, N.J., assignor to Foster Wheeler Corporation, New York, N.Y., a corporation of New York Continuation of application Ser. No. 137,154, Sept. 11, 1961. This application Sept. 21, 1964, Ser. No. 397,855 4 Claims. (Cl. 122-478) This is a continuation of application Serial No. 137,154, filed September 11, 1961, now abandoned.

The present invention relates to a novel baffle arrangement for water tube marine boilers and, in particular, to a tangent tube arrangement for baffling marine boiler screen tubes for the fiow of hot gases across a super heater, which superheater is coextensive with an area of said screen tubes.

The purpose of a baffle in a marine boiler is to direct hot furnace gases over a heat-absorbing tube surface in a manner to reduce the temperature of the gas to a minimum with a reasonably low draft loss.

In vapor generators having a superheater, a conventional marine boiler arrangement may comprise a single combustion chamber with a plurality of laterally adjacent, vertically oriented banks of steam generating tubes extending between a steam drum and one or more water drums. A superheater is generally positioned between two of the banks extending substantially from the front to the rear of the boiler parallel to the longitudinal axes of the drums. A vapor generator of this type may also have a plurality of roof and wall tubes extending to the steam drum along the roof of the combustion chamber. One of the banks of screen tubes, generally the inner bank, i.e., the bank adjacent the combustion chamber, is bafiled in the area above the superheater to prevent furnace gases from passing to the flue without giving up heat to the superheater.

Conventional boiler installations for this purpose customarily use castable refractory baffles disposed around the inner bank of screen tubes, but modern high capacity, hi h temperature installations require that the superheater, with the necessary baffling, be moved closer to the furnace. This results in more severe furnace conditions, and it has been found that the castable refractory deteriorates or breaks up by reason of excessive movement of the screen tubes.

One approach proposed for bafiling the screen tubes above the superheater has been to dispose the upper portions of the screen tubes'in tangent relationship. However, the tubes must be diverged from each other in the area of the steam drum to be accommodated in the drum surface. It has been suggested to use fins to close the area between the diverging tubes, but this is not feasible since the width of the fins would increase to the point where they could not be adequately cooled.

According to the present invention, there is provided in a vapor generator a battle arrangement which overcomes the above disadvantages, and which directs the flow of hot furnace gases for most effective removal of heat from the gases with minimum draft loss.

Specifically, the invention involves providing, in a marine boiler having a steam drum, a superheater generally below the drum, and banks of roof and screen tubes emanating from the steam drum defining in part a combustion chamber, the screen tube bank being between the combustion chamber and the superheater, a baffie arrangement in which a row of tubes of the screen tube banks are extended upwardly or disposed so as to be tangent to or come in contact with tubes of the roof tube bank at a point of tangency Or contact removed from the steam drum. The tubes of both banks are diverged or separated slightly from one another before entering the steam drum so as to be accommodated in the drum, but the screen tubes so extended enter the drum grouped with the roof tubes so that refractory can be poured between all of the tubes in question sealing the area between the point of tangency and the drum.

In a direction away from the drum and away from the point of tangency, the individual tubes, which provided the tangency are themselves in tangent relationship and/or otherwise bafiled to effectively complete the screen between the superheater and the drum so as to direct the flow from the combustion chamber across the superheater.

In describing the tubes or rows of tubes as being in tangent relationship or in contact, it should be under stood that the tube walls per se may be contiguous, i.e., closely spaced on normal screen tube centers or in actual contact, or the tubes may be spaced somewhat apart from each other and provided with fins which are contiguous, the relationship being such as to substantially prevent the flow of gases between the tubes.

It is believed that other features and advantages of the invention will become apparent upon further consideration of the specification and accompanying drawings in which:

FIGURE 1 is a sectional view, in elevation, of a boiler according to the invention;

FIGURE 2 is an enlarged sectional, elevation view of the baffile arrangement of FIG. 1;

FIGURE 3 is a fragmentary sectional view taken along line 3-3 of FIG. 2;

FIGURE 4 is a fragmentary sectional view similar to FIG. 3 of an embodiment of the invention;

FIGURE 5 is a fragmentary sectional view taken along line 55 of FIG. 1.

Referring to FIG. 1, there is illustrated a single water tube marine boiler according to the invention having a setting 10 comprising side walls 12 and 14, a front wall 16, a rear wall (not shown), floor 18 and roof 20. A steam drum 22 is positioned adjacent the top of the boiler in roof 20, and is connected to a water drum 24 positioned at the bottom of the boiler in floor 18 by two banks of boiler screen tubes 26 and 28. The banks of screen tubes are disposed between a combustion chamber 30 of the boiler and a flue 32. Combustion gases are provided by burners 34 mounted in the front wall 16 of the setting 10.

The tube bank 26 remote from the combustion chamber, hereinafter referred to as the outer bank, comprises a substantially greater number of tubes than the bank 28 immediately adjacent the furnace chamber 30, which bank will be hereinafter referred to as the inner bank. A superheater 36, schematically shown in FIG. 1 is arranged between the two banks of screen tubes 26 and 28, and is disposed approximately intermediate the banks of screen tubes and intermediate the water and steam drums. Roof tubes 38 are provided leading from the steam drum 22 and extending downwardly along the side wall 12 to a collection manifold 40 in communication with the water drum 24. Rear wall and front wall tubes 42 are disposed above the roof tubes and extend from the steam drum 22 towards the side wall 12, bending at substantially towards the rear and front walls covering the walls in a conventional manner.

The superheater 36 may be conventional comprising a nest of U-shaped tubes arranged one within another lying in substantially horizontal planes, the open ends of the U-shaped tubes extending outside of the boiler into headers which are not shown. The superheater terminates at the base of the boiler near the water drum 24 and at the top substantially short of the steam drum, so that, without bathing there would exist above the e3 superheater a passageway by which furnace gases could pass through the inner bank 28 to the flue 32 without passing through the superheater 36. The present invention resides in the provision of an improved baffle arrangement by which this by-passing of furnace gas around the superheater is prevented, or by which furnace gases are constrained to How past portions of the screen tubes coextensive with the superheater.

Referring to FIG. 2, the invention is illustrated in greater detail.

The roof tubes 38 and rear and front wall tubes 42 extend substantially radially from the steam drum 22 in the area immediately beneath the roof 20. Spaced circumferentially from the roof and wall tubes, the inner bank of screen tubes 28 also extends radially from the steam drum as illustrated.

In a standard construction of roof and screen tubes, the main length of the inner bank of screen tubes is approximately perpendicular to the main length of roof and wall tubes, the screen tubes approaching the roof and wall tubes until about within one foot of the same. The screen tubes are then bent at about 90 and parallel the roof and Wall tubes until they enter the steam drum tube sheets, while the roof and wall tubes continue in a radial direction from the steam drum parallel and adjacent to the roof of the boiler.

According to the invention, rows of screen tubes of the inner bank, preferably the rows adjacent the combustion chamber, are displaced or extended upwardly from this conventional disposition and the roof tubes 38 are displaced or bent downwardly until the roof tubes and screen tubes are in a tangent relationship at a point 48 removed from the surface of the steam drum.

In the embodiment illustrated in FIGS. 2 and 3, the tubes of a first row 44 of the inner bank are extended until they are brought into a tangent or contiguous relationship with alternate tubes of the roof tube bank at the point 48, while the tubes of a second row 46 of the inner bank are also displaced or extended from their conventional disposition until they are in tangent relationship with the remaining tubes of the roof tube bank. In both instances, the point of tangency for the screen tubes is past that point at which the screen tubes are bent at about 90 towards the steam drum. The tubes of additional rows of the inner bank, i.e. the row furthest removed from the steam drum, combustion chamber, follow their normal disposition.

To make it clear what is meant by tangent relationship, tubes defining a screen against the flow of combustion gases will be on predetermined centers so as to effectively present a gas flow barrier. The screen tubes 44 and 46 of the inner banks will be on the same centers at the point of tangency, not only with respect to each other, but also with respect to the roof tubes 38.

Between the point of tangency and the steam drum, the displaced screen tubes are grouped With the roof tubes to enter the drum more or less with the roof tubes.

In the area of the roof tubes between the point 48, of tangency, and the steam drum, a castable refractory 49 is provided sealing the area about the roof tubes. The refractory also flows around the screen tubes grouped with the roof tubes, and is extended outwardly from the steam drum into the area 50 above the roof tubes shielding the wall tubes 42 from the furnace and separating the roof and wall tubes.

Refractory around the roof tubes in the area 49 conventionally withstands severe furnace conditions. It was only refractory around screen tubes, in conventional installations, that was subjected to deterioration. By the invention, it was found that grouping of the displaced screen tubes with the roof tubes, in effect making the screen tubes part of the roof tube bank in this area adjacent the steam drum, provided the result that the re fractory around the screen tubes withstands the movement of the tubes as well as that around the roof tubes.

From the point of tangency 48 to a second point 52 near the top of the superheater 36, and across the furnace from the front to the rear wall, the rows 44 and 46 of screen tubes, which are continguous with the roof tubes, are provided with fins 54 disposed between the tubes to prevent the flow of furnace gases through the screen tubes in this area. By aligning rows 44 and 46 of the screen tubes into a single row, the fins may be made of minimum width for adequate cooling thereof.

Below the point 52 and in the area coextensive with the superheater the rows of tubes, 44 and 46, are diverged or separated from each other, as illustrated in FIG. 1, to permit the free passage of air past the tubes. This is also illustrated in FIG. 5 which shows the screen tubes 44 and 46 in the area above the superheater in alignment or defining a baffie surface with fins 54 closing the gaps between the tubes, and the tubes 46 in the area below the point 52 diverging from the tubes 44 towards the combustion chamber.

It should be noted that the section line 3-3 is taken along a broken line to show the fins 54 bridging the gaps between the tubes 44 and 46, and to show the castable refractory 49 disposed around the roof tubes 38. The refractory 49 is preferably poured into place to effectively close off any passageways for the flow of gases (at the point of tangency 48) between the fin surfaces 54 and the refractory 50. By off-setting the screen tubes 44 and 46 from the roof tubes 33, a more effective baffling is obtained since the castable refractory 49 can be poured close to the fins 54 at the point of tangency.

Instead of using fins, the screen tubes themselves may be contiguous with each other in the area between the point of tangency 48 and the superheater to provide baffling. This arrangement is illustrated in FIG. 4 showing the tubes 44 and 46 as closely spaced and without fins.

It is apparent from the above description that the invention eliminates the need for bathing of the screen tubes in the area between the point 48 of tangency and the steam drum, and provides a bafile surface above the superheater defined by the tangent screen tubes 44 and 46, the point of tangency 48, the tangent roof tubes 38, and the refractory material 49 and 50, by which the furnace gases are constrained to pass through the screen tubes in an area coextensive with the superheater and are prevented from by-passing the superheater.

Various modifications will be apparent to those skilled in the art. For instance, the invention is readily applicable to types of boilers other than the specific type described and shown in the drawings. Accordingly, the present invention is to be limited only as defined in the following claims.

What is claimed is:

1. A vapor generator comprising a combustion chamber, an upper steam drum, a bank of roof tubes and at least one bank of steam generating screen tubes entering said steam drum, a superheater co-extensive with at least a portion of said bank of screen tubes, said superheater and screen tubes being arranged such that the screen tubes shield said superheater from said combustion chamber, said roof and screen tubes being disposed whereby tubes of said bank of roof tubes are in tangent contiguous offset relationship and on a triangular pitch with tubes of said bank of screen tubes and nested into the spacing between the latter at a point of tangency removed from said steam drum, the screen tubes being contiguous to each other at said point of tangency, the roof tubes and screen tubes tangent thereto being in grouped and triangular relationship between the point of tangency and the steam drum, a castable refractory poured into the spacing around the roof tubes and between the roof and screen tubes at the point of tangency to the steam drum sealing the area around said bank of roof tubes and the screen tubes against the flow of combustion gases between said point of tangency and the steam drum, said screen tubes which are tangent to said roof tubes also being tangent to each other from said point of tangency to a second point adjacent said superheater to provide a bafiie surface whereby hot furnace gases from said combustion chamber are constrained to flow past portions of said screen tubes coextensive with said superheater.

2. A vapor generator according to claim ll, wherein said roof tubes are bafiied from said point of tangency across the roof of said combustion chamber.

3. A vapor generator according to claim 1, and includ ing fins between the screen tubes from said point of tangency to said second point adjacent said superheater.

4. A vapor generator comprising a combustion chamher, a substantially horizontal upper steam drum, a substantially horizontal water drum disposed below said steam drum, multiple banks of upright steam generating screen tubes disposed adjacent said chamber and extending be tween said steam drum and said water drum, one of said banks having a bent construction including upper and lower approximately horizontal runs and a substantially vertical run therebetween defining with another of said upright banks a space between the steam drum and said water drum, a superheater disposed in said space, a bank of roof tubes entering said steam drum in a direction approximately parallel to said upper run of said bank of bent screen tubes, said upper run of said screen tubes and the bank of roof tubes being arranged whereby tubes of one are disposed in tangent contiguous offset relationship and on a triangular pitch with tubes of the other and nested into the spacing defined by the latter at a point of tangency removed from the steam drum, the screen tubes which are tangent to said roof tubes also being tangent to each other at said point of tangency and from said point of tangency to a second point further removed from the steam drum and adjacent to the superheater to provide a bathe surface whereby hot furnace gases from the combustion chamber are constrained to flow past portions of said screen tubes co-extensive with the superheater, the roof tubes and screen tubes tangent thereto being in grouped and triangular relationship between the point of tangency and the steam drum, a castable refractory poured into the spacing around the roof tubes and between the roof and screen tubes at the point of tangency to the steam drum sealing the area around said bank of roof tubes and the screen tubes against the flow of combustion gases between said point of tangency and the steam drum.

References ited by the Examiner UNITED STATES PATENTS 2,206,265 7/40 Saathofi 122-235 2,327,161 8/43 Badenhausen l22--473 2,834,327 5/58 Banker 122510 FREDERICK L. MATTESON, 1a., Primary Examiner. KENNETH W. SPRAGUE, Examiner.

Claims (1)

1. A VAPOR GENERATOR COMPRISING A COMBUSTION CHAMBER, AN UPPER STREAM DRUM, A BANK OF ROOF TUBES AND AT LEAST ONE BANK OF STREAM GENERATING SCREEN TUBES ENTERING SAID STREAM DRUM, A SUPERHEATER CO-EXTENSIVE WITH AT LEAST A PORTION OF SAID BANK OF SCREEN TUBES, SAID SUPERHEATER SAID SCREEN TUBES BEING ARRANGED SUCH THAT THE SCREEN TUBES SHIELD SAID SUPERHEATER FROM SAID COMBUSTION CHAMBER, SAID ROOF AND SCREEN TUBES BEING DISPOSED WHEREBY TUBES OF SAID BANK OF ROOF TUBES ARE IN TANGENT CONTIGUOUS OFFSET RELATIONSHIP AND ON A TRIANGULAR PITCH WITH TUBES OF SAID BANK OF SCREEN TUBES AND NESTED INTO THE SPACING BETWEEN THE LATTER AT A POINT OF TANGENCY REMOVED FROM SAID STEAM DRUM, THE SCREEN TUBES BEING CONTIGUOUS TO EACH OTHER AT SAID POINT OF TANGENCY, THE ROOF TUBES AND SCREEN TUBES TANGENT THERETO BEING IN GROUPED AND TRIANGULAR RELATIONSHIP BETWEEN THE POINT OF TANGENCY AND THE STEAM DRUM, A CASTABLE REFRACTORY POURED INTO THE SPACING AROUND THE ROOF TUBES AND BETWEEN THE ROOF AND SCREEN TUBES AT THE POINT OF TANGENCY TO THE STEAM DRUM SEALING THE AREA AROUND SAID BANK OF ROOF TUBES AND THE SCREEN TUBES

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