US2777407A

US2777407A - Fuel burning apparatus

Info

Publication number: US2777407A
Application number: US311963A
Authority: US
Inventors: Schindler Ewald
Original assignee: Babcock and Wilcox Co
Current assignee: Babcock and Wilcox Co
Priority date: 1951-10-02
Filing date: 1952-09-29
Publication date: 1957-01-15
Anticipated expiration: 1974-01-15

Description

Jan. 15, 1957 E. SCHINDLER FUEL BURNING APPARATUS Filed Sept. 29, 1952 INVENTOR Wa/d ckind/er BY ATTORNEY United States Patent Ofiice 2,777,407 Patented Jan. 15, 1957 FUEL BURNING APPARATUS Ewald Schindler, Oberhausen, Germany, assignor to The Babcock & Wilcox Company, New York, N. Y., a corporation of New Jersey Application September 29, 1952, Serial No. 311,963

Claim priority, application Germany October 2, 1951 Claims. (Cl. 110-28) The present invention relates to fuel burning apparatus and more particularly to the construction and operation of a cyclone type furnace having a cylindrical combustion chamber to which a pulverized fuel-air mixture is introduced through a burner at one end while a substantial proportion of the combustion air is introduced through ports distributed longitudinally of the chamber. The burner is suitably formed with a star-form distributor head having radially extending nozzle arms through which the incoming fuel-air mixture is directed into the chamber in jets parallel to the front wall thereof.

In certain forms of cylindrical cylone furnaces heretofore constructed or proposed, the coarsely pulverized or granular fuel particles, such as coal, which are introduced tangentially into an end portion of the combustion chamber, are required to travel in a helical path a substantial distance, depending on the size of the particles, before such fuel particles are brought into contact with the supply of secondary air which is introduced tangentially at the maximum periphery of the combustion space. As a result, that part of the combustion space which lies in the vicinity of the fuel-introducing burner is not used to the fullest extent for combustion, while the remaining available space may still not be suflicient to permit complete combustion of all fuel particles within the cyclone chamber particularly with certain grades of fuels. As a result, the combustion chamber temperatures are lower than they would be if combustion of the fuel were completed within the primary chamber, and the fluidity of the resulting slag may therefore be deficient. These phenomena are particularly manifested with the relatively low volatile fuels whose combustion reactions proceed more slowly. With such fuels, an at tempt to obtain complete combustion of the fuel within the limits of the furnace chamber has entailed a lengthening of the cylindrical combustion space. However, since the lengthening of the combustion space also involves an increase in the surrounding fiuid cooled wall area, the desired effect is thereby at least partially offset.

It has also been proposed, for the purpose or" making the space in the region of fuel introduction available for combustion, to arrange in the end wall of the cyclone furnace, close to its periphery, one or more supplementary burners which are directed axially into the secondary combustion air introduced tangentially at the periphery. With such an arrangement of supplementary burners, a ring of flame is provided adjacent the front end wall which results in the development of a high temperature zone in the foremost part of the chamber and thus accelerates combustion of the major fuel supply. However, supplementary burners arranged in this manner involve additional structural features which result in increased complication and cost of the assembly.

According to the invention, therefore, it is herein proposed to provide a burner having a star-form distributor head which, being arranged directly adjacent the inner face of the front wall and parallel thereto, results in the total fuel-air mixture being subdivided and discharged into the chamber in a large number of outwardly directed radial jets. The fuel, and specifically, the total quantity of fuel fed to the burner, is in this manner uniformly distributed over a large area and thus results in the creation 'of conditions particularly favorable for ignition. Moreover, since the total length of the cyclone furnace is in this way made. available for combustion of the fuel, there is assured a complete combustion of fuel within the cyclone chamber.

The various features of novelty which characterize my invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which I have illustrated and described a preferred embodiment of my invention.

Of the drawings:

Fig. l is a central longitudinal sectional view of a cyclone furnace embodying burner means arranged in accordance with the present invention;

Fig. 2 is a transverse sectional view of the furnace shown in Fig. l, as seen along line 22; and

Fig. 3 is an additional transverse sectional view of Fig. l, as seen in separate parallel planes along line 3-3.

The cyclone furnace, as herein illustrated, includes a main combustion chamber A, of substantially circular cylindrical formation, having a fluid cooled circumferential wall or boundary 2 formed with fluid conducting tubes 3 which are embedded in a layer of refractory material 4. Outwardly of the refractory material there is provided an insulating layer 5 and also an outer sheet metal jacket 6. The outer end wall 7, of generally planar formation, suitably at right angles to wall 2, is of similar construction, as indicated. At the opposite end of the chamber, the transverse wall 8 is formed with a fluid cooled central reentrant throat section 9 by which a. circular :gas outlet 10 is defined. A slag outlet 11 is formed in a lower portion of wall 8.

The granular fuel-air mixture is introduced into chamber A through a fuel inlet pipe or conduit 12 of circular cross section, arranged co-axially of the chamber, and formed interiorly with helically arranged ribs 13 by which the mixture is distributed throughout the total internal cross section of the conduit. At the inner end of conduit 12, a distributing head section 15 is provided by which, through radially extending arms or nozzles 16, at equal circumferential spacing, the total incoming primary air-fuel mixture is divided into a relatively large number of separate streams which are projected outwardly through nozzles 16 in circumferentially separate directions in a plane parallel to the outer end wall 7. Nozzles 16 are suitably of tapered formation, as shown, whereby the internal fiow area is decreased progressively toward the outer discharge tips. The fuel-air inlet conduit 12, including the nozzle head 15 at its inner end, is arranged axially within an air inlet conduit 17 which extends through an opening 18 in the outer furnace wall 7. Air is admitted in regulable quantity to conduit 17 through an exterior supply conduit 19, under control of damper 20.

The inner end of air inlet conduit l7'extends through the furnace wall opening 18 and, being IPP rted therein, opens into a "cup-shaped burner head 21 which is formed with refractory walls and positioned over the inner end of the wall opening. In the cylindrical burner head wall or skirt 22, there are formed rectangular openings 23 into which the outer ends of nozzles 16 project, leaving separate surrounding areas 25 through which air from conduit 17 is discharged peripherally of the respective primary air-fuel nozzles 16. A transverse partition 26 is arranged at the inner margins of openings 23 so as 3 to define an inner compartment 27 from which air is saparately discharged into chamber A through other sets of

openings

28 and 29 Air is supplied to the inner head chamber 27 through pipes 31 which, at their outer ends, receive a regulable supply of air from a duct 32, under control of damper 34. The larger discharge openings 28 are arranged in a single circumferential row at an outward inclination so as to provide a generally frusto-conical pattern of jets. The smaller openings 29 are formed in the planar end face of burner head 21 and provide jets which extend parallel to the longitudinal axis of chamber A. The pipts 31 are suitably of triangular cross section since in this form they may be advantageously installed in the crotch between successive tapering nozzles 16 and thus provide a more compact assembly. With this arrangement, the pipes 31 also provide support for the star-shaped distributor head 15, since each pipe 31 is supported at one end by the partition 26 and, at its opposite end, by the outer wall of air conduit 17.

Secondary combustion air is introduced at high velocity into the combustion chamber A through ports 35 which open tangentially into the chamber adjacent the end wall 7, thereby producing a whirling movement of the fuelair mixture entering radially through nozzles 16. Additional tangentially directed secondary air ports 36 are provided, as may be required, whereby a whirling movement of the total fuel-air stream is maintained throughout the length of the chamber.

While in accordance with the provisions of the statutes I have illustrated and described herein the best form of the invention now known to me, those skilled in the art will understand that changes may be made in the form of the apparatus disclosed without departing from the spirit of the invention covered by my claims, and that certain features of the invention may sometimes be used to advantage without a corresponding use of other features.

I claim:

1. A cyclone furnace having a circumferential wall defining a combustion chamber of generally circular cross section about a central axis, burner means associated with an end wall of said chamber and comprising a distributor head formed with nozzles extending outwardly with respect to said axis for discharging a primary air-fuel mixture in jets directed toward said circumferential wall along circumferentially separate paths, conduit means arranged axially of said burner means for supplying said air-fuel mixture to said distributor head and thereby to said nozzles, means adjacent said end wall for introducing secondary air into said chamber in a stream directed tangentially along the inner face of said circumferential wall, said burner means including a head member in which openings are formed about the discharge ends of said nozzles, and means for admitting air to the interior of said head member for discharge through said openings.

2. A cyclone furnace as defined in claim 1 and further characterized by said head member having a compartment therein from which a separate body of air is directed in jets longitudinally of said combustion chamber.

3. A cyclone furnace having a circumferential wall defining a combustion chamber of generally circular cross-section, means for burning a particle-form solid fuel in said cyclone furnace, said fuel burning means being associated with an end wall of said chamber and including fuel discharge nozzles adjacent to said end wall and arranged for discharging primary air and entrained solid fuel particles outwardly into said chamber along circumferentially separated paths, and a burner head surrounding said fuel discharge nozzles and having circumferentially spaced air inlets arranged to discharge addi tional air into said chamber at positions adjacent said fuel discharge nozzles, air inlet means adjacent said end wall arranged to introduce secondary air into said chamber in streams directed tangentially along the inner side of said circumferential wall, and gas outlet means formed in a wall at the opposite end of said combustion chamber.

4. A cyclone furnace having a circumferential wall defining a combustion chamber of generally circular cross-section, means for burning particle-form solid fuel in said cyclone furnace under a mean furnace temperature above the fuel ash fusion temperature, said fuel burning means being associated with an end wall of said chamber and including fuel discharge nozzles adjacent to said end wall and arranged for discharging primary air and entrained solid fuel particles radially outwardly into said chamber along circumferentially separated paths, and a burner head surrounding said fuel discharge nozzles and having circumferentially spaced air inlets arranged to discharge additional air into said chamber at positions adjacent said fuel discharge nozzles, air inlet means for introducing secondary air into said furnace in a stream directed tangentially of said circumferential wall in substantially a common plane with said air entrained fuel particles, gas outlet means formed in a wall at the op,

posite end of said combustion chamber, and means forming a slag outlet at the lower part of said furnace chamber adjacent the gas outlet.

5. In a furnace of the cyclone type having a combustion chamber of generally circular cross-section about a central axis, the improvement which comprises burner means arranged at one end of said chamber and having a distributor head formed with nozzles extending outwardly with respect to said axis for discharging a primary air-fuel mixture into said chamber in jets directed transversely of said axis, conduit means arranged axially of said burner means for supplying said air-fuel mixture to said distributor head and thereby to said nozzles, said burner means including a head member having a cylindrical skirt portion formed with openings in which said nozzles are respectively received in spaced relation to the walls of said openings, means including a conduit joined to said skirt portion for supplying air to said openings for admission to said chamber, a partition within said burner head member forming the inner wall of a compartment from which air is directed longitudinally of said combustion chamber, and means for supplying air to said compartment including tubular members extending transversely of and between successive nozzles.

References Cited in the file of this patent UNITED STATES PATENTS 1,614,314 Murray et al. Jan. 11, 1927 1,618,808 Burg Feb. 22, 1927 1,637,772 Heckel et al. Aug. 2, 1927 2,368,827 Hanson et al. Feb. 6, 1945 2,458,992 Hague Jan. 11, 1949 FOREIGN PATENTS 228,507 Great Britain Apr. 23, 1925 302,255 Great Britain Dec. 11, 1928 975,610 France Oct. 17, 1950