US1888110A - Furnace grate - Google Patents

Description

1932- A. w. BENNIS 1,883,110

FURNACE GRAI 'E Filed March 14, 1929 5 Sheets-Sheet 1 F EIW A. W. BENNIS FURNACE GRATE Nov. 15, 1932.

Filed March 14, 1929 5 Sheets-Sheet vz/vroe agwzaam #rrai/ma A. W. BENNIS FURNACE GRATE Nov. 15, 1932.

5 Sheets-Sheet 3 Filed March 14. 1929 ATTORNEKS.

NOY.-

A w BENNIS FURNACE GRATE Filed March 14, 1929 S Sheet S-Sheet 4 FIQM. 56 Fig.5.

ATTORNEYS.

A. W. BENNIS FURNACE GRATE Nov. 15, 1932.

Fild March 14, 1929 5 Sheets-Sheet 5 Patented Nov. 15, 1932.

UNITED STA j- '1,sss,110 l f ALFRED winmam BENNILS, on oLTon' nGLANn FURNACE GBATE' Application flIedMarc-h 14, 1929; Serial No. 347,068, and m Great-Britain March 14,1s2s

The present invention relates to furnace grates and more particularly of the chain grate type.

Under modern conditions of combustion,,

5 particularly with regardto electricity supplystation practice the use of heated air' for.

theair supply toithe furnace is demanded and as a consequence of the passage of the heated air between the grate bars'or through said grate bars or their air spaces and also as a consequence of the high temperature furnace conditionsabove the grate, theseare liable to become overheated, causing them to deteriorate, crack and eventually burn away. a A fur l5 ther detrimental feature arises in that when the fire bars become heated in 'chain grates,

the fuel tends to when the bars which. produces a condition known as cauliflowering, with the result that the efliciency of combustion is impaired and. the output is reduced with the result that the" furnace has, to be slowed down and the grate cooled.

The tendency of modern conditions is to,

continually demand higher air temperature supply to the furnace, and itris extremely likely that as time goes on an air supply of even greater temperature will be required.

With a view to meeting these-demands, the object of the present inventionistoprovide means whereby links orfire bars of the V grate may be kept cool independently of the temperature of the air supply through the grate so that while in use the dered substantially unburnable;

grate bars, a connection being formed be} tween the inlet of said air passages" and a cool air chamber below the grate bars, whilst the exit of the air passage or passages is coning off the warm air from the warm air compartment. In the latter case, the warm air taken off may be utilized for combustion purposes. i

of the passages in the grate is ren- Accordingly to the present invention one or more an passages are provided in the;

r :scribe'd with reference to theaccompanying v In apreferredform of construction, the. V 0

grate bars are mounted on hollow carrier bars which are divided into a plurality of compartments by. suitablediaphragms, or

division's. One Or more of these compartments is utilized for the transm ssion ofcool air from'the source tOthB filI passages in the and thence tojthe'combustion chamber or further to air heaters to befurtherheated' and then utilized. forcombustion; v I Any suitable form of connection-may. be 7 I used between the grate bar'sian'd thecarrier bars. Preferably these connections. are in the form of tubes extending between the ends graterbars and the orifices in the carrier ba l The ainmay be forced by a fan or the like means "through the 'cool air compartments of the rhollow carrier bar and the'n through a the links or grate bars'in parallel after which '75 it passes into the warm air compartment in the, hollow carrier bars and thence onfto trunksor conduits toair'heaters after which it passes through said air heaters onto-hot" lair trunksto the underside-of the grateagain '80 where it' passes up to burn the fuel on the grate.

Trunks-or ,conduits' may be arran ged to conveythe coolrai-r to themoving hollow carrier bars from the cool airysupplyf means, whilst additional trunks areutilized to con- 'vey the heated air away from the hollow carrier bars. No mechanical difliculty exists in this transfer of the air from the'conduit to the hollow c arrier'b'ar'or from'the hollow carrier bar to the trunk as .air has been 'fed totravelling chain grate compartments in a number of ways in the past;

It will be obvious that the hollow carrier bars may have more than one entrance forts.

drawings, in which-'1 mg air to the grate bars.

Figure 1 is a plan view of a general ar-g rangement of a grate constructed according. to the present invention.

Figure2 is asectional elevation of the grate on the line BB of Fig. 1.

Figure 3 is a transverse section of the grate along the line A-A of Fig.2.

Figure 4 is a plan view on a larger scale, of a portion of the grate. I 1

Figure 5 is an enlarged transverse section of the grate across a portion of this'only.

Figure 6 is a section through a portion of the longitudinal upper run of the grate.

Figure 7 is a transverse section of a por-;-

tion of a modified arrangement for supply- 7 F igure' 8 is a sectional viewthrough. a

grate bar and hollow carrier bar on which said gratebar is mounted showing one method-of interconnection between said grate bar and its carrier bar for the purpose of allowing air to pass through the grate bar.

'Figures 9and 10 show modified forms of construction in which the grate bars are cast on tubes connected to the hollow carrier bars. Figures 11, 12 and 13 aredetail views of a modified arrangement for the supply of air to the grate bars, Fig. 11 being a transverse section throughthe hollow carrier" bar, Fig. 12 being a corresponding lOIlgltllClll'lELl view in elevation and 13 beingacorrespond ing longitudinal view in plan.

Figures 14 and 15 show a modified arrangement for the air supply to the drop link type of stoker, Fig. 14 being a transverse section across a portion of the upper run of the grate and Fig. 15 being a view in elevation over a portion of the longitudinal run of the grate. Figure 16 is a perspective view showing the various parts diagrammatically in their relationship to one another.

In the general arrangement as shown in Flgs. 1-3 of the drawings, the inlet ducts for supplying cool air forpassage through the grate'bars areillustrated at 20 and the exit ducts through whichthe' warm air isled away,preferably to assist in the combustion onthe grate, are illustrated at 21, combustion air ducts being illustrated at 22.

It will be seen'from a study ofthese drawtending transversely over the whole or a portion of the grate are shown at 25, whilst the rollers for supporting the carrler bars are illustrated at 26 in Fig. 2.

' Turning to Figs. 4-6 0f the drawings it Wlll be seen that each transverse carrier'bar is formed with a pair of compartments 27, 28 separated by a division wall or diaphragm 29.

A plurality of hollow grate bars 30 are mounted on each carrier bar.

rier bars are illustratedin Fig. 6. i p

YVith regard to the manner in which the extreme left hand grate bar is mounted on its carrier bar, it will be seen that a plurality of lugs 31 are formed on the upper face of reach hollow carrier bar at spaced intervals along this, these lugs 31 being adapted to receive guides 32,the lower portions of which are bifurcated to rest on such lugs 31 whilst the upper portions of which are T- shaped to be engaged by T-shaped recesses in the grate bars. The grate bars are hollow asillustrated at 33, the passages through the grate bars being connected to the chambers 27 and 28 of the hollow carrier bars so that cool air supplied upwardly through the transverse cold airqduct 20. passes into the longitudinally extendedportion of such duct 23 and thence into chambers 27 of all those carrier bars situated above said longitudinally extended upper portion 23 of the cold air duct whereupon the cold air passes through the grate bars on said carrier'bars and thence into the .warm aircompartment 28 of said carrier bars, whereupon the air which has been warmed in its passage through the grate bars is exhausted into the longitudinally extended upper portion 24 of; the transverse warm'air duct 21. If desired, the'warm air is then led ofi-to air heaters for further heating and to subsequently assist in supporting combustion of the fuel on the grate.

'Any convenient arrangement may be adopted for mounting the grate bars on to the transverse hollow carrier bars, A number of such arrangements are illustrated in Figs. 8-13. I V

In the construction according to Fig. 8-the grate bars 34 have passages 35 formed. therein, the inlet to -such passage 35-being connected to a tube 36 whilst the exit of the passage '35 is. connected to the tube 37.

The tube 36 further is connected with a cool air compartment 38 of a carrier bar 39 whilst the tube 37 is connected to the warm air compartment 40 of'said hollow carrier bar..

These tubes 36, 37 may either be cast'inlor otherwise suitably secured to the carrier bar 39 and the opposite ends inserted just within the inlet and exhaust ends respectively of the passages35', or alternatively such tubes may beca'st with such grate bars 34 and their ends inserted, priortofuse on the grate within the orifices formed in the upper face of the 1101- low carrier bar 39 V V In the modified form of construction shown in. Fig. 9 a hollow carrier bar 41 is provided of substantially triangular cross section, the

Various methods'of mounting these grate bars on the carinto the warm air compartment of such car-- rier bar. 7 Y 7 In the further modified form of construc tion illustrated in'Fig. 10 each grate bar48 is cast on atube 49,one end of whichtube-is insertedin the cool air compartment 50 of the hollow carrier bar 51 whilst th eopposite end is inserted in the warm air compartment52 of, such carrier bar. p H

It will be seen that in'the arrangements illustrated in Figs. 1-6 and Figs. 8-10, the

cool air passes from the cool air compartment of each carrier bar throughthe' grate bars mounted thereon in parallel andthen passes to' the warm air compartment of the carrier bar.

In the construction illustrated a Figs.

11-13 the cool 'air passes through a number of grate bars in series before returning to the;

warm air compartment ofthe lcarrier bar. By this, it is not meant to infer that the 'air passes through every grate baron any single carrier bar in parallel prior toentering the warm air'compartment of such carrier bar. Preferably, separate streams'of cool air each 'pass through about six grate bars prior to entering the warm air compartment of the carrier bar.

In Figs. 11-13 the carrier bar is illustrated at 51 and its cool andwarm air'compartments at 52 and 53 respect ively-whilst the grate bars mounted- .on the carrier bar are illustrated at The air passes along a coiled tube. in

series througha number of laterally adjacent grate bars 54,1'which are formed by casting the metal of the grate bars around, the tube.

In a further modified form of construction (not illustrated. in the drawings) the tube itself may form the hollow grate'bar and for this purpose, is'suitably shaped. and treated. It will be appreciated that in: a very narrow grate one coil'ov'er each'carrier bar may be suflicientin which case it would not be necessary for the carrierbarjtobe hollow, as means may be arranged at the inlet and outlet oi' the coil to feed to and from the cool andvwarm air ducts. In wider -grates;;however, it would be preferred toprovide a'number of series coils, the number dependingon the coolness and speed of airpassing there through forcooling purposes.

In Figure 16, the ash pit 1O has'the grate above it, of which only the one carrie'rbar'25 opsuing-22 into the ash pit is shown, "with'the one grate bar or link v thereon. The other figures of the drawings show that a lar e number of carrier bars, each with a great number "of gratebars 30 may be employed. The carrier bar'is substantially oft-he form shown in Fig.8, with the central partition dividing it along its length into; compartments 38 and 40; Air pumped from compressor 11' by motonM passesthr0ugh the cold air duct 20 into the-inlet trunk23 which .ifo'rms a manifold, and hasan aperture in its upper surface. Thisaperture, it will be un derstood, is norm'ally'closed by a plurality of tlie jbars 25. In this conventional figure,'tl1e carrier bar 25'has been shown-away from its definite position, for greaterclearnessr The .arrows indicate thefiow of coldair from-the 'coi'npressor 1 1-through"an openlnglt into the compartment 3810f the carrier bar 25. Each of the grate bars 3O- has a passage 32 through it by which airmay' pass from the coidi'air' compartment 38 intothe hot air compartmentAO. -A-t the other end of theillustr ated carr er bar 25; -this hot'airpasses through the opening 15 and an aperturein tliel'top outlet trunk or manifold 24 to the hot air duct-'21. Thencetlie air-moves through I an air heater 12shown conventionally as con 'nec'tedto the hot air pipe 18 leading to'the 10-whence the air moves upward betweenthevariouscarrier bars 251 and gratebars 30 into the'ifire bed. 1 For the purpose of illustr'ating an arrange;

ment which maybeemployed for adapting Tthe present invention to the drop link type of stoker referencefis made to. Figs' 14 and 15 of the drawings. In thesefigures the cold-air inlet is illustrated at 56 andthe hot airexit" Cold air passes fronitheinle'toGupthrOugh a'vert-icalconduit 58 and 'thenceoutwardly at 59' intopassages 60 formed in links 61{ The air 'is heated in its' travel along the passages thence into the hot airexit 57 (SQ-and returns to a verti'cal' conduit 62 and tween a plurality'of laterally adjacent links It will'thus be seenthat coldair may bef ed f up through a verticalconduit situated be- I or grate bars and "emerges from these links A or grate bars at the opposite ends thereof.

In this wayjasingle cold airinlet only is necessary for each pair of laterally adjacent groupsiof. grate bars. In' the form ofjcon'struction Fig. '7 a longitudinal cold'air duct 68 is pro vided as distinct from thetransverse cold air ducts already de'scribed whilst'similar remarks apply to the longitudinalhot 'air ducts 64, these ducts 63 and' 6d being connected to vertical ductsor passages*65,i66' with the cold air compartments and hotair com: I I "partm'ents respectively of thevariouscarrier bars; 7

Incor'der to prevent the -h'ea'tedair which isjj fed tothe-furnace- 0r. cells under thegrate illustrated in.

from leaking into the cool air conduit grates, sliding joints or the like, air at a higher pressure is utilized in the conduit to the cool air compartments in the hollow carrierbar thanis used under the grate. s

A number of cool air conduits may be utilized to feed cool air to the hollow carrier bars sothatsuch carrier bars may be fed with cool air at different pressures according totheir position of travel along the furnace.

It will be obvious that the means for 0001 ing the grate bars as described above may be combined with the air supply regulating means described in the specifications accompanying my patent applications Serial Nos. 311,169, filed October 8,1928, and 334,772, filed January 24, 1929. 1 v

I declare that whatI claim is n 1. A furnace grate comprising stationary longitudinally directed and transversely spaced air inlet and outlet trunks having top apertures, hollow carrier bars operable to' travel over said trunks and to substantially close said apertures and having bottom apertures positioned to register with theapertures of the trunks, hollow grate bars mounted on said carrier bars and communicating therewith so "that air may pass between the cavities of said grate and carrier bars, means for supplying air to said inlet trunk, said inlet, trunk and carrier bars and grate bars providing passages for the air therethrough to said outlet trunk, and means for withdrawing air from said outlet trunk. I

2. A traveling furnace grate comprising hollow carrier bars and hollow grate bars mounted thereon, each carrier bar containing a longitudinal partition dividing it into two compartments, means "for placing the cavia: ties of the grate bars mounted on the carrier bars in communication with each ofsaid compartments, and means for supplying air to one of said compartments, the other of said compartments having an outlet.

3. A traveling furnacegrate comprising hollow carrier bars and hollow gra'tebars' mounted thereon, each said carrier bar con taining a longitudinal partitiondividing it into two compartments, an air inlet conduit for delivering air into one compartment, an air outlet conduit for permitting the escape of air from the' other compartment, and

means for placing the cavities of the grate bars mounted on the carrier bars in commu-' nication at theirends with an inlet and an outlet compartment of said carrier bars.

4:. A traveling furnace grate comprising hollow carrier bars and pluralities of hollow grate bars mounted thereon, conduit means for connecting the grate bars of each pluralitv so'that the. air may flow in succession through the bars of such plurality, each carrier bar containing a longitudinal partition dividing 1t mto: two compartments, means for placing the cavity of the one end grate nasano bariof. eachplurality in communication with one said compartment and'the' cavity of the other end grate bar of each'plurality in com- I munication with the othersaid compartment,

each said carrier bar and grate, wherebythe grate bars may be removed without disengagement of the carrler bars.

6.; A furnace-grate asin claim 2 in which the grate bars comprise-tubes and fuel supsporting structures formed upon the tubes,

and the ends of each tube being connected to a carrier bar whereby to establish the com- :munication of thecavity of the tube with the two compartments of thecarrier bar.

[71A furnace grate as in claim 2 in which the grate bars are provided with tubes fixed thereto and extending relatively downwardly therefrom, vand hollow connecting means are provided on the grate bars for engaging said tubes whereby to form said communication means between the cavities in saidgrate bars and said carrier bars. v

8.,A; furnace grate comprising stationary air trunks extending lengthwise of the grate and having apertures on their upper surfaces, hollow carrier barslocated above said air trunks and extending transversely; of the grateand having bottom apertures in communication with said trunks throughsaid trunk aperturesand providing airinlet and outlet-7' compartments alternately extending transversely of the grate, a plurality of hollow grate bars mounted on said carrierbars andincommunication at their ends with the air inlet and outlet compartments thereof,and

means for supplying air to one of said trunkswherefrom itmay'pass to the air inlet compartments, the other of said trunks having an outlet. 7 p p a p '9. A furnace grate comprising a plurality ofhollow carrier bars and means for con- 1 n'ecting the same to travel in chainto form a traveling furnace grate structure, a plurality of hollowgratebars for formingthe fuel supporting surface of thegrate mounted on each of saidcarrier bars,sai'd carrier bars extending transversely of the grate and being provided with lengthwise 'internal partitions dividing them each into? two compartments, each said hollow grate bar-having connections to each. of said compartments of the hollow-carrier bar upon which the grate bar is mounted.

10. A. traveling furnacegrate comprising hollow grate bars for forming the fuel supporting surfaceof the grate, fixed air inlet and outlet conduits extending along the grate, hollow members extending across the grate "and providing airinlet and outlet compartments in communication with said conduits, and connections for supporting said grate bars on sald hollowmembers and mcludmg conduits for establishing communication between the'cavities of the grate bars and said compartments so that air may flow from said inlet conduit through said inlet compartment and said grate bars to cool the said grate bars and be discharged therefrom through said outlet compartment and outlet conduit.

In witness whereof, I have hereunto signed my name this 26th day of February, 1929.

ALFRED WILLIAM BENN IS.

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