US2840051A

US2840051A - Convection fluid heat exchange unit with integral soot blowers

Info

Publication number: US2840051A
Application number: US325328A
Authority: US
Inventors: Paul M Brister; Jr John C Singleton
Original assignee: Babcock and Wilcox Co
Current assignee: Babcock and Wilcox Co
Priority date: 1952-12-11
Filing date: 1952-12-11
Publication date: 1958-06-24
Anticipated expiration: 1975-06-24

Description

J1me 1958 I P. M. BRISTER EI'AL 2,840,051

CONVECTION FLUID HEAT EXCHANGE UNIT WITH INTEGRAL SCOT BLOWERS Filed D60. 11, 1952 3 Sheets-$heet l INVEINV'IILLJRS j au/Mfirister YJo/m C. Singlefionjr F I 1 ATTORNEY June 24, 1958 P. M. BRISTER ETAL 2,840,051

CONVECTION FLUID HEAT EXCHANGE UNIT WITH INTEGRAL SCOT BLOWERS 3 Sheets-Sheet 2 Filed Dec. 11, 1952 INVENTORS azz] Mfirisi'er lam/B1122 Cfing/etozgJr ATTO R N EY M. BRISTER ET AL June 24, 1-958 2,840,051

CONVECTION FLUID HEAT EXCHANGE UNIT WITH INTEGRAL SOOT BLOWERS Filed Dec. 11, 1952 3 Sheet -s 3 r rJ G Em 0 fl. m EM 5 v C Z 1 a 0 w B 8 G F A 0 Mi.

ATTORNEY Patented June 24, 1958 CONVECTION FLUID HEAT EXCHANGE UNIT WITH INTEGRAL-800T BLOWERS' a Application December 11, 1952, Serial No. 325,328

1 Claim. (Cl. 122-392) This invention relates to gas heated fluid heat exchange units of the convection type.

More specifically the invention is concerned with the provision of a permanent or fixedtype of soot blower as an integral part of a vapor generating unit involving a bank of vapor generating tubes heated by high temperature heating gases. The purpose of the soot blower is to promote cleanliness of the Vapor generating tube surfaces subject to heating gas contact. Such gases generally have suspended solids therein, and inthe opera tion of the unit some of these solids are deposited on the tubes. Such deposits decreasethe heat transfer rates from the heating gases to the vaporizable liquid within the tubes. The invention provides a fixed soot blower operable to remove such depositis by the periodic operation of high pressure fluid jets directed against the tube surfaces which have had such solids deposited thereon. The jets are directedthrough nozzles or jet structures leading from a tube disposed in proximity to the main bank of convection tubes and disposed in the same gas flow zone. When the soot blower jets are operative the soot blower tube is protected against destructive heating effects of the gases by the cooling of metal by the soot blowing fluid, but asthis fluid flows only periodically, the soot blower tube needs other thermal protection during the periods of inoperation of the soot blower jets. The invention provides such protection byv enclosing the soot blower tube within an outer tube connected into the same fluid circulation system as that in which the main convection heating tubes are connected.

Thus, for example, a vapor generator having a bank of upright vapor generating tubes heated by high temperature gases has one or more of the tubes enclosing a soot blower tube. The inner and outer tubes are connected by a multiplicity of jet structures welded to the tubes and directed radially toward the remaining, and adjacent tubes. The soot blower tube is thus maintained at a temperature of the order of the temperature of the vaporizable fluid even when the soot blower is inoperative. This reduces thermally created stresses in the inner and outer tubes and in their welded connections which also unite the soot blower jet structures to them.

The invention, in a more specific sense, involves such fluid heat exchange soot blower improvements in a unit operating at such high gas pressures that the entire convection heat exchange components must be enclosed within a pressure vessel. This is an arrangement which would practically exclude the use of retractible soot blowers.

In the pertinent unit, oxygen and methaneare introduced into a reaction chamber under pressures in the range of 250-350 p. s. i. a., and in such proportions that their reaction results in heating gases of a temperature of the order of 2500" F. These gases are directed over ends of these tubes are connected with a liquid and vapor drum arranged exteriorly of the tube enclosing pressure 2 vessel, and the lower ends of the vapor generating tubes communicate with the liquid space of that drum by downcomer connections extending through the pressure vessel wall. These connections may include lower drums or headers circumferentially arranged within the pressure vessel and having the lower ends of difierent banks of the vapor generating tubes directly communicating therewith. Similarly arranged upper headers or drums may have the upper ends of the vapor generating tubes directly connected thereto within the pressure Vessel. The high gas temperatures involved emphasize the need of thermal protection for the fixed soot blower tubes, a plurality of which are provided for each bank of vapor generating tubes.

When the pertinent unit involves a multiplicity of recurrent transverse gas passes over each bank of tubes, a corresponding multiplicity of transverse gas pass baffles are provided, and the soot blower jets are therefore preferably arranged in vertically spaced groups disposed at positions vertically spaced from the levels of the baflies with each transverse gas pass having its own series or group of soot blowers arranged for optimum cleaning of the tube portions within that gas pass.

For the purpose of compliance with the pertinent statutory requirements, the invention is concisely set forth in the appended claim, but for a better understanding of the, invention, its characteristics and results, reference should be had to the accompanying description of a preferred embodiment illustrated in the accompanying drawings:

In the drawings:

Fig. ,1 is a partial sectional elevation through the heat exchange unit involving convection heated tube bundles for vapor generation; 7

Fig. 2 is a sectional elevation of one of the tube bundles incorporating the illustrative soot blower constructions;

Fig. 3 is a partial horizontal section on the line 33 of Fig. 1;

Fig. 4 is partly an elevation and partly a sectional elevation of one of the soot blower constructions employed with each of the tube bundles of the Fig. 1 unit;

Fig. 5 is a vertical section through one of the soot blower constructions, on an enlarged scale;

Fig. 6 is a partial elevation of one of the soot blower constructions showing a group of the soot blower jet structures; I

Fig. 7 is a transverse section on the line 77 of Fig. 6 showing the relationship of the soot blower jet structures to the inner soot blower tube and its enclosing vapor generating tube which is one of the tubes of a tube bundle;

Fig. 8 is a transverse section illustrating the annular and concentric relationship of a soot blower tube and its enclosing tube taken on the line'88 of Fig. 5;

Fig. 9 is a detail view partly in elevation and partly Theheat exchange unit of Fig. 1 involves a pressure vessel 10 in the lower part of which there is a furnace, or

gaseous reactionc'hamber 12 having high temperature

refractory walls

14 and 16 and a refractory roof 18. In one example of this unit, methane is burned in an atmos phere of oxygen, producing high temperature gases which pass recurrently transversely of the upright vapor generating tubes of the tube bundles. Each tube bundle connects a lower header or drum 20 to an upper header or drum 22, the vapor generated in the tube elements collecting in the upper header 22 and passing through the vapor discharge tube 24 to an external vapor and liquid drum (not shown) which is connected to the upper part of the discharge tube "24by a series of circulators 26.

There are series of transverse baffles which cause the heating gases to pass recurrently transversely of the tubes of each tube bundle. One series of these baflles includes the removable central battles 28-31 removably disposed within the annular arrangement of tube bundles, and vertically spaced as indicated in Fig. l. battles is indicated by the baifles 34-36 extending from the outer parts of the baflles 2831 and partially through the tube bundles.

Interposed relative to the baffles 34-36 are baflles 38 41 which extend partially through the tube bundles from the outer wall of the gas space. The lower'headeror drum 20 of each tube bundle is supplied with the vaporizableliquid by downcomers 44 which are indicated as passing through the upper part of the pressure vessel 10,

Another series of j at 45. These downcomers preferably communicate with the liquid space of an external vapor and liquid drum.

After leaving the upper parts of the tube bundles the heating gases exit from the pressure vessel through an opening provided by gas discharge conduit 46 which is preferably of such diameter that any one of the tube bundles including its upper and

lower headers

22 and 20,

maybe bodily removed through it.

The annular arrangement of the tube bundles is indicated in Pig. 3, with tapered refractory 'baflles 50 closing the spacesbetween successive tube bundles. Between the.

downcomers 44 at the rear of the tube bundles and the wall of the pressure vessel 10, there are vapor generating wall cooling tubes 52 having space closing heat resisting material 54 therebetween. These tubes are connected into a fluid circulation system by appropriate connections including upper headers 55 and circulator tubes 56 extending upwardly from the headers. These circulator tubes exit through the upright wall of the pressure vessel at positions indicated at 58 and 60, and, to minimize thermally created stresses the circulators have helically disposed portions v62 interposed relativeto the headersSS and positions 58 and 60. The upper ends of the circulators may be connected to the external vapor and liquid drum and the lower ends of the wall tubes appropriately connected to the liquid space of the vapor and liquid drum.

Disposed centrally of each tube bundle and at a posi tion close to thedowncomers44 is a soot blower structure 64, and a similar structure is disposed at each in ner corner of the tube bundle at the positions indicated at 66 and 68 in Fig. 3. The soot blower structure 64 as shown at the right hand part of Fig. 2 includes an inner soot blower tube 70, concentrically fixed within an outer tube 72 by spacers 7476 (Fig. 8) and the soot blower jet structures such as 77 and 78. These jet structures include short tubular sections extending through openings in the outer tube 72 and expanded therein or welded thereto, for pressure tightness. The inner end of each jet structure is welded to the inner tube 70 as indicated at 80, a small diameter opening 82 through the wall of the tube7tl providing for the flow of high pressure steam or other fluid through the jet structure. Preferably, the

openings 82 are formed by drilling the innertu'be after the jet structures are welded in their operative positions.

The lower end of each outer tube such as 72 is connected to the lower drum ZtF by a tubular element 84, and the upper end of the" outer tube 72 is similarly in communication with the drum 22 through a tubular element 86, these elements being connected'in pressure tight relationships. a

Fig. 6 shows one group of the soot blower jet structures such as 77 and 78, six jets being shown in this group. Such groups are disposed at the positions A, B,

C, D, E, F and G along the soot blower structure 64 so furnace.

' mized.

The jets of the soot blower structure 64 are directed at different radial positions into the associated tube bundle as indicated by the arrows -92 in Fig. 3. The soot blower structures 66 and 68 toward the inner parts of the tube bundles are constructed similarly to the mannot above described, each having an outer tube such as 94 or Q6 with an inner tube 98connected to a source of high pressure fluidsuch as the vapor in the external vapor and liquid' drum. The groups of soot blower jet structures for the soot blower structure 68 are disposed at positions such as indicated at H, L], K, L, M and N iniFig. 2.

Fig. 5 indicates a welding of the tubular connection 84 to the lower end of the Outer tube 72 and the welding of the upper end of the latter around the inner tube 70 at 100.

Fig. l indicatesthat. the lower parts of the interiormost soot blower structures such as 66 and 68 are of an outside diameter less than the upper parts of these structures. The upper parts of these structures include external tubes 94 which are 4" in diameter and the vaporizable fluid flows tubes and the internal tube 98 for the soot blowing fluid.

hese tubes 98, like the tubes 70 previously described, are

connected to a source of soot blowing fluid of a temperature of the same order as the temperature of the vaporizable fluid in the annual passage 104 in order that stresses arising from temperature gradients may be mini- The upper parts of the inner soot blower structures are constructed in the manner above described, but the lower parts are of somewhat different construction. These -lower parts include the outer tubes 108 which are of a diameter of 2". Theyare welded as at 110 (Fig. 9) to the outer tubes 94. However, before this welding takes place the inner tubes 112 having radially positioned soot blower jetelements 116 welded thereto as indicated at within the outer tube 108. The elements 116 are disposed in successive groups along the length of the

tubes

108 and 112, one of such groups being indicated at 118, the various elements 116 being aligned with openings in the outer tube 108.

After the elements116have been welded to the tube 112, the latter is welded asindicated at 120 to the lower end of the inner tube 98. Thereafter, the outer tube 108 is slipped over the inner tube 112 and its projecting elements 116 so that the latter align with openings formed in the tube 108. Thenth'ese openings are filled with weld metal such as that indicated at 122. Thereafter, this weld metal and the elements 116 inwardly thereof are drilled to form thesoot blower jet ducts,"one of which is indicated at-124 in 'Fig. 10. These may be of a diameter of the order of A". Each of the outer tubes 108 of the soot blower structures 66'and 68 is connected to a header 20 by a short tubular element 126, welded to 'the tube 108 as indicated at in Fig. 9. 1

It will be noted from an examination of Fig. lthat the smaller diametertubes 108 of the lower portions of the soot blower element 68 are mainly disposed beneath the baflie 18 which forms the 'roof of. the high temperature Thus, these elements are subjected to temperatures much greater than the portions of the soot blower elements at higher levels, and to keep the tube metal of the elements 108 within allowable limits, the surface exposed to the gases is decreased, relative tothe gases contacted surfaces of the upper parts of those-soot blower structures. The illustrative arrangement of multiple diametered soot blower structures also provides for the as to effectively remove solids-from the parts of the tube bundles disposed between the successive baffles such as 36 -41. 6

expansiouofthe'fluid or fluid mixture within the annular parts of the soot blower structures, the percentage of steam of vapor increasing from thebottom of those structures, upwardly,

Although the invention has been described with refer ence to the details of a preferred embodiment, it is to be appreciated that the invention. is not limited to all of these details. It is rather to be considered as of a scope commensurate with the scope of the subjoined claim.

What is claimed is:

In vapor generating apparatus, in a bank of upright vapor generating tubes, said tubes being horizontally spaced apart for the flow of heating gases therebetween, an upper pressure vessel chamber to which the upper ends of all the tubes are connected, a lower pressure vessel chamber having lower ends of all the tubes connected thereto, a soot blower tube disposed within one of the first mentioned tubes so as to leave an annular space exteriorly of the soot blower tube and within its enclosing tube, intermediately disposed soot blower jet structures welded to the soot blower tube and its enclosing tube and forming soot blowing jet passages leading from the interior of the soot blowing tube through its enclosing tube and directed toward the remainder of the first mentioned v 6 tubes, and means for connecting the inlet of the soot blower tube with a source of soot blowing fluid, the soot blower tube having a part of reduced diameter at a position remote from its inlet.

References Cited in the file of this patent UNITED STATES PATENTS