US2748754A

US2748754A - Fluid heat exchange unit with a furnace having gas deflecting inner wall surfaces

Info

Publication number: US2748754A
Application number: US319079A
Authority: US
Inventors: Lotz Otto
Original assignee: Babcock and Wilcox Co
Current assignee: Babcock and Wilcox Co
Priority date: 1952-11-06
Filing date: 1952-11-06
Publication date: 1956-06-05
Anticipated expiration: 1973-06-05

Description

June 5, 1956 o. oTz 2,748,754

FLUID HEAT EXCHANGE UNIT WITH A FURNACE HAVING GAS DEFLECTING INNER WALL suRFAcEs Filed Nov. 6, 1952 v v A mmm ' 36 INVENTOR F|GI 2 BY O ,ZOZ

ATTORNEY United States Patent FLUID .HEAT 4EXCHANGE UNIT .-A FUR- vISVACE.HAVING GAS DEFLECTING INNER WALL "SURFACES "`.ttLotz,.0berhausen,.Germany,.a1ssignor to The Bab- ,cock 1.-&- Wilcox Company, NewYork, N. Y., .a corpontonofNewfJersey Application November, 1952, Serial N o. '319,079

v4 Claims. (Cl. -122-2-35) '.l`h`is'inven'tion relates to fluid heat exchange apparatus o'flthe typehaving afurnace burning a slag forming fuel. The walls of theffurnace linclude vaporpgenerating wall .tubes sLibjectstoJthe'heat ofthe furnace. vThe invention .is more particularly concerned .with such a unit, operating at temperaturesabove the'fusion temperatures of the slag or non-combustible vof .the fuel. 'One of 'the-major problems encountered inthe operation of .such `a unit is 'the separation ofthe slag from 'the gaseous combustion products so'that'the-slag will not excessively accumulate uponconvection .heat 'exchange components contacted by the combustion'products at positions beyond 'the furnace. The invention" promotes the 'solution of this "problem vby increasingimp ingernent of the burner llames upon the `furnace Walls.

"Inapreferred-exeniplicationrof the invention a corner `fired 'furnace :has Ywalltu'be sides A'so "angled -with respect tolthe'fprojectionof the flames lfrom the yburners that'the flames Ysweep thefurnace walls to a high degree. The fuel andairastreamsare introduced at the furnace corners vand are Vdirected Ytoward 'and yover ladjacent Lfurnace walls Ydisposed-in converging relation to the V1longitudinal axes Y-o'flthe fuel land air jets projected by'theburner means. 'The 4slag accumulates upon -the walls in a molten state, 'owsdown lthefurnaeewalls and Lalong the furnace iloor 'lwhichhas 'a central'slag dischargeopeningrthrough which fthe;sla'gfrexits' from the unit.

:'In :another yaspect of the yinvention different .and lateral adjacentisectionsrofaffurnace wall includeedge or mar- ,fginl `sections having an iacute vangle relationship. ,In Xone-.ofthe edge sections, :a fuel and air mixture enters the furnace .as a jet 'through that section fand the angularly :related section is so disposed withreferenceto the fbnrnerzsection that the furnace gases are directed away from ,the 'burner Y:port from lwhich 4the lfuel land air jet renters .the furnace. When .a .plurality of such Vfurnace walls are .arranged between `successive 4and similarly ar- ;ranged burners the furnace gases have `a circular vor rcyclonic path .within fthe furnace, .and Athe :combustion -products :from 'a Y,leading burner .zare idirected away from 4theffuelfandzair.jetgportsyof thesucceeding burner. This arrangement would .promote effective lring 'of the ffur :nace'reven under conditions A.where one-burner burns -fuel such =as natural -gas and an adjacent burner is red by aplverizedf'fuel and airmixture.

'lhe'fspecicfsbject matter of the invention'is 4particularly set forth l'inthe appendedclaims, but, fora 'better understanding Aof lthe invention, its characteristics and advantages, reference shouldbe hadto'the'accompanying drawing and descriptionwhich disclose apreferred em- `bodinrent of the invention.

'In the drawing:

Figl is a,plan..of the illustrative furnace; and

'Eig l. is a .sectionalclevation showing the furnace and agpartof asuperposedradiation chamber.

The :furnaceof Fig. .l has .walls .2-55 including strata v6 :and .7 of vnon-metallic heat resisting material. :The

ICC

Such intersecting Vinterior walls, or wall surfaces, are indicated at 9, lihand 111, along the exterior 'furnace wall the exterior wall'Z; and'l, 19 and'20 alongthe exterior ,wall

At each `corner of the furnace the interior walls, l.or wall surfaces, .such as 10, 11 and.12, are arranged to form a .channel-like pocket, or recess opening toward the center of .the furnace, and in .each recess fuelburning ,means are arranged. 'For instance, in the furnace wall 4, and extending through the interior .wall surface '11, there is afuel and air (pulverized coal with carrier air) tube (or ,burner tube) 21 having its longitudinal axis AB so disposed as to direct a jet'of pulverized'fuel and air along the line .of that axis, and in convergent relation to the interior wall or Wall surface 12 so that the projected combustion elements sweepxthat interior wall. `The tube 21 and its fuel and air jetare directedat an acute angle to'the'plane ofthe interior wall'2.

A second "air jet ris Vdirected 'through the Wall 1E) 'by the duct `orccnduct 22 yandar a greater acute angle Lto lthe'wall 12, as shown, and ontheother sideof the fuel `and air 4jet from -the tube Zi'another'secondary air jet `is Adirected from the ytube-22 along the'wall 12, as indicated Jby the arrow 2S. Similar arrangements ofl fuel and air `jets are provided by the vburner tubes '2li-2&5V at the `remaining furnace corners, along with similar secondary airfietsfroni theducts or conduits 27h-'32.

'-With this arrangement of interior furnace Walls or wall sections such as 13--17 relative Yto1the fuel vand air jetsthroughthe tubes or conduits suchas'2S,j26, and 2'9-32, Vthefflames lfrom the jet *

tubes

26, 31 and32 are deflected away frorn'the burner vport of the'jettube `25 by reason of the rinclination of the interior Wall or :wall section "15. Thus, stabilized flame `and `ignition conditions in front of the wall ports 'of jet tubes v25, 29 and '30 are promoted v"by -the prevention of the vtransversely moving lcombustion products Vfrom interfering with ythe operation of a following burner, such as `thatformed

bythe jet tubes

25, 29 and 30. The transversely moving combustion products here referred to are those moving'across the front-of the Jburner vrecess and the kburner forrnedf'by the

tubes

25, 29 and '-30.

The furnace of this application maybe regarded as having a plurality of similarly directed `fuel burning rneansdisposed at successive lpositions angularly or .circumferentially spaced perimetrically of the furnace. These `fuel burning means so'direct fuel and air streams substantially tangentially into the v'furnace that the vfurnace gases have a substantially circular path Within thefurnace. The furnace may be also regarded as having interior wallportions (illustrated in the drawings at '9 to f2() inclusive) which include yvapor generating tubes and form ateach of the-spaced positions of thefuel burning means 'a fuel Vand air mixing chamber, or fuel burning pocket, keach of lthe pockets rbeing disposed exteriorly oi the maximum circular path ofthe vfurnace gases within the furnace. The -fuelburning means maybe regarded as having fuel `and Vair jet tubes supplying fuel 'and air toeach pocketor fuel and air-mixing chamber. Thefjet tubestterm'inate Within the pocket and exteriorly of the vmaximum circular fpath the ymovement Vof -the 'furnace gases within "the furnace. The above indicated wall .portions ymay '.be :regarded `as including the Jdeflecting `walls .15, =18,'9:andf12, .eachipreceding a pocket or ifuel and air :mixing .chamber Yin :the direction of rotation of the gases within the furnace, and angled inwardly away from its pocket so as to deflect the rotating gases from or inwardly out of the pocket. For example, the pocket in which the jet tubes and 29 inject air streams may be regarded as having the furnace gases deflected away therefrom by the preceding detlecting wall portion 15.

With the pertinent arrangement of furnace components the advantages of tangential or corner ring are maintained, with the characteristic high turbulence due to the cumulative tangential relationship of the burning fuel streams to an imaginary circle (such as 33) within the combustion chamber. Additionally, when a slag forming fuel is burned, a higher degree of separation of the suspended slag particles and their suspending gases is attained by the increased sweeping and impingement of the combustion products over or against the angled interior furnace walls 9, 12, 15 and 18. The molten slag particles contact the interior furnaces, agglomerate thereon, and then tlow down those walls to the furnace floor. They then flow along that tloor to the central slag discharge opening 35 where they exit from the furnace.

The furnace floor has extensions 36 of the wall tubes 8 disposed therealong. These tubes extend to the

lower headers

37 and 38, and other appropriate tubular elements, through which they are connected into the fluid system of the illustrative unit.

At the tops of the furnace walls the wall tubes have converging roof parts 39 extending to the furnace gas outlet 40. Thence, succeeding parts of the tubes diverge along the

inclined walls

42 and 43 of the radiation chamber 44. From these walls

further parts

45 and 46 of the tubes are disposed along the

upright walls

47 and 48 of the radiation chamber, as shown in Fig. 2. At the top of this chamber (not shown) the tubes may be appropriately connected by suitable headers and circulators to a steam and water separating drum, the water space of which is preferably directly connected to such lower headers as 37 and 38.

The radiation chamber 44 is divided by rows of

vapor generating tubes

49 and 50 having the more divergently related parts 51 presenting a downwardly opening channel for the manifold 52 from which additional secondary air is directed through the nozzles 53 downwardly toward the furnace gas exit 40. From the level of the mauifold 52, the division wall tubes further converge downwardly in widely spaced relationship, to form the

tubular screens

54 and 55. The screen tubes extend through the

inclined walls

42 and 43 to juncture with the

headers

56 and 57 which are appropriately connected into the circulatory system of the unit. They are preferably connected with the water space of the conventional steam and water separator drum by downcomer tubes.

Whereas the invention has been described with reference to the details of a preferred embodiment thereof,

it is to be appreciated that the invention is not limited to all of the details described. It is rather to be taken as a scope commensurate with the scope of the subjoined claims.

What is claimed is:

l. In a vapor generating unit, a furnace, similarly directed fuel burning means disposed at successive positions angularly or circumferentially spaced perimetrically of the furnace, said fuel burning means so directing fuel and air streams substantially tangentially into the furnace that the furnace gases have a substantially circular path within the furnace, interior wall portions of the furnace including vapor generating tubes and forming a fuel and air mixing chamber or a fuel burning pocket at each of said positions disposed exteriorly of the maximum circular path of the furnace gases within the furnace, the fuel burning means including fuel and air jet tubes supply ing fuel and air to each pocket, the jet tubes terminating within the pocket, said wall portions including a plurality of gas deilecting walls each preceding a pocket in the direction of rotation of the gases within the furnace and angled inwardly away from that pocket to deflect the rotating gases away from the pocket and toward the furnace center, tubes of each deilecting wall constituting a surface of a pocket, each of said deilecting walls angled toward the detlecting wall for the next succeeding pocket to direct the gasesand suspended combustion elements toward the deflecting wall for the next succeeding pocket, at least one of said jet tubes for each pocket directed obliquely toward the defiecting wall of the same pocket.

2. ln a vapor generating unit, a furnace, separate and similarly directed coal burning means disposed at successive positions angularly or circumferentially spaced perimetrically of the furnace, said fuel burning means so directing fuel and air streams substantially tangentially into the furnace that the furnace gases have a substantially circular path within the furnace, and interior wall portions of the furnace including vapor generating tubes and forming a fuel and air mixing chamber or a fuel burning pocket at each of said positions disposed exteriorly of the maximum circular path of the furnace gases within the furnace, the fuel burning means including fuel and air jet tubes supplying fuel and air to each pocket, said wall portions including a plurality of gas deflecting walls each preceding a pocket in the direction of rotation of the gases within the furnace and angled inwardly away from its pocket to deflect the rotating gases away from the pocket and toward the furnace center, the tubes of each deflecting wall constituting a surface of a pocket, the air and fuel jet tubes of each fuel burning means being angled oblquely of and toward the gas detlecting wall of the same pocket and directing the burning fuel stream sweepingly over that gas deilecting wall each of said deecting walls angled toward the corresponding deflecting wall of the next succeeding pocket to direct gases and suspended combustion elements toward the corresponding deilecting wall of the next succeeding pocket.

3. In a vapor generating unit, a furnace, separate and similarly directed coal burning means disposed at successive positions angularly or circumferentially spaced perimetrically of the furnace, said fuel burning means so directing fuel and air streams substantially tangentially into the furnace that the furnace gases have a substantially circular path within the furnace, and interior wall p0rtions of the furnace including vapor generating tubes and forming a fuel and air mixing chamber or a fuel burning pocket at each of said positions disposed exteriorly of the maximum circular path of the furnace gases within the furnace, the fuel burning means including fuel and air jet tubes supplying fuel and air to each pocket, said wall portions including a plurality of gas detlecting walls each preceding a pocket in the direction of rotation of the gases within the furnace and angled inwardly away from its pocket to deflect the rotating gases away from or inwardly of the pocket, the air and fuel jet tubes of each fuel burning means being angled toward the gas deilecting wall of the next succeeding pocket and directing the burning fuel stream toward and sweepingly over that gas defleeting wall, one air jet tube for each pocket directing a stratum of air along and immediately adjacent the first part of the deilecting wall of that pocket and a second air jet for each pocket directed toward said deilecting wall and toward said stratum and thereby increasing the fuel and air sweeping action of the detleeting wall and preventing action which otherwise would eect air insulation of the deflecting wall.

4. In a vapor generating unit, a furnace having a plurality of similar series of meeting upright wall segments including vapor generating wall tubes, the adjacent series of wall segments meeting at a plurality of corner posi tions so as to form pockets opening toward the interior of the furnace and disposed exteriorly of the maximum of circular gas movement within the furnace, means with in each pocket for corner tiring the furnace with pulverized coal by the direction of streams of combustion elements out of the pockets and generally tangentially to an imaginary circle indicating the general movement of combustion elements within the furnace, each series of Wall segments including one major segment or deecting Wall segment presenting a wall surface at a small acute angle to the direction of firing from the pertinent pocket and facing that tiring, the surfaces of said major wall segments extending generally in planes generally tangentially to said circle at points in advance 0f the points of tangency of the directions of firing from successive pockets, the volume of the pockets outside of said circle constituting a large fraction of the volume of total furnace space, the fuel exit ports of the firing means being disposed radially outwardly of the circle to an extent equal to a major part of the radius of the circle, a furnace oor constructed to provide a slag discharge opening, and walls providing a radiation chamber disposed beyond the furnace with respect to gas ilow, said last named walls being further constructed to provide a constricted furnace gas outlet leading to the radiation chamber and disposed centrally with respect to said circle, the pulverized coal burning means including an air jet in each pocket directing an air stream immediately adjacent and parallel to each major wall segment (or deilecting wall segment) and another air jet directed against said major segment and said air stream to increase the fuel and air sweeping action of the deecting wall segment.

References Cited in the tile of this patent UNITED STATES PATENTS 1,905,283 Heaton Apr. 25, 1933 1,917,275 Rossman et al. July 11, 1933 1,966,054 Wheeler July 10, 1934 2,044,270 Wood June 16, 1936