US2411918A - Grate for burning solid fuel - Google Patents

Description

DecQa, 1946. R1 V WRIGHT 2,411,918

`GRATE FOR BURNING SOLID FUEL Filed Sept. 5, 1944 6 Sheets-Sheet 2 Dec 3, 1946- R. c. WRIGHT 2,411,918

@RATE FOR` BURNING soLID FUEL. I

I Filled Sept. 5, 1944 v f6 Sheets-Sheet 3' x m 4 NN Q4 L. Il

m, lll Imm Dec.3, 1946. l RvcfWRlGH-r I 2,411,918,

GRATE FOR BURNING SOLID FUEL Filed sept. 5, 1944 e sheets-'sheet 4 n [v1/@Wok C Wwe/97." 5km ra/mfr GRATE FOR BURN'INGVSOLID FUEL Filedl Sept. 5, 1944 6 Sheets-Sheet 5 5;@ Qi I n imi. g; L

ec. 3, 1946. R. c. WRIGHT GRATE FOR URNING SOLID FUEL Filed sept. 5, 1944 6 Sheets-Sheet 6 I'IIII.

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Patented Dec. 3, 1946 GRATE FOR BURNING SOLID FUEL Richard C. Wright, Bay Village, Ohio, assignor to Iron Fireman Manufacturing Company,

Portland, Oreg.

Application September 5, 1944, Serial No. 552,720

7 Claims.

The main object is to provide a grate of the class described which will minimize the amount of riddlings passing downwardly through the grates by means of a special arrangement of air ports, wherein each vertical port is located directly under a horizontal rib which is considerably Wider than the air port, thereby eliminating any possibility of fine particles falling through the air ports. Riddlings are .also prevented from passing downwardly'through the grate sections by special seals between adjacent grate bars.

The second object is to provide a grate of the class described having improved air distribution brought about by having each air port disposed horizontally against an opposing air stream, thereby diffusing the air at the grate level and greatly reducing the maximum localized velocity Ipressure of the air leaving the grate in a vertical direction. The distribution of air is further improved by maintaining abit of loose ash between the ribs of the grate bars of sufficient depth to provide uniform air diffusion, which is not a common characteristic of other types of grates. The grate bars on the top of the grates hold sufficient ash between to insure complete air diffusion at all times, regardless of the'skill or care used by the operator in cleaning the iire.

The third object is to provide an improved form of seal between adjoining grate bars, these seals effectively closing the clearances between the grate bars at al1 times and in a very iiexible manner. and form a means of justifying the grate bars much in the manner in which type is justified by varying the spaces between the adjacent bars in order that the over-all dimension may be easily controlled, and at the same time providing flexible means of actuating the grate bars to repeated. expansions and contractions. A tight seal is maintained at each end of a grate bar by so arranging them that one end of each grate is supported by the next grate in line. the grate bars themselves being loose in their support bars and so arranged that they are free to float in any direction in order to seat themselveson the end seal ledge of the next grate bar. ,n

The fourth object is to provide a grate of the class described which will remain unusually cool in operation due to the .high degree of area exposed to the cooler air in the plenum chamber in comparison with the very small amount of area exposed to the fire. The, only portion of the grate which is ever directly exposedto therflre is a very narrow strip on topof each rib. Cross ribs are provided betweenl the main ribs to insure the retention 'of a protective layerA of' ash on the grates even when the grates are in the dumpe position, thereby eliminating the source of high maintenance commonly experienced with other types of dumping grates, and also preventing the usual period of poor burning conditionsV encountered with other` types of grates immediately after being dumped bare.` Y Y The fifth object is toY provide a grate of the class described which is especially adapted for use with a Stoker of the spreader type. Aspreader type stoker which is adjusted to give proper coal distribution under normal running conditions (grates covered with ash) will notgive uniform distribution on a bare grate. On a bare f' grate the coal tends to accumulate at the rear because of the tendency for the pieces of coal to ricochet from the hard surface. Thismeans that after the grate is raked or dumped. clean, uniform coal distribution is slow to establish itself; and until the 'grates' become sufciently covered to correct the coal distribution, the combustion of the coal is poor.V -It is to overcome his diiliculty that the present type of grate has been devised.

The'sixth object is to devise a grate of the class described which would be simple to assemble,

install and adjust without the employment of special skill or tools. This is established by causing each grate bar to float on its bearing bar entirely independent of the other grate bars. i

The operation of leveling the bars is greatly simplified and if any bar is damaged, it can be replaced by simply lifting it out and dropping the replacement bars in place.

The seventh object is to construct a grate of the class described in which the dumping grates are constructed on steel bearing bars with replaceable cast iron bearings at each end, thereby affording the advantages of the cast iron bearings and the greater strength of the structural steel grate supporting bars.

The eighth object is to provide supporting beams which are strong enough to support the load and yet will protectthe supporting beam from becoming overheated as the air cooled bearing grates prevent the beams from coming into contact with the radiant heat of the re, and due to this construction break up any downward ow of conducted heat. This construction also lends itself readily to the use of partitions for zoning of the plenum chamber.

The ninth object is to provide a grate support assembly which becomes a rigid steel structure `which is entirely independent of the boiler' or furnace setting. This arrangement eliminates distortion due to expansion or contraction of the brick work.

The tenth object is to afford an easily replaceable form of skirt for the lateral marginal dump` ing grates to prevent pieces of clinker from getting underneath the dump grates and pinching between the dump grate and the bearing grate, which would make it diicult to close the grates when they are in the open position.

I accomplish these and other objects in a manner set forth in the following specification as illustrated in th accompanying drawings, in which:

Fig. 1 is a fragmentary plan of the grates showing the brick work cut away in the horizontal sectio-n.

Fig. 2 is a fragmentary View showing a section of the dumping grates in elevation and showing the supporting structure in brick work in section taken along the line 2 2 in Fig. 3, but showing the dump grates level.

Fig. 3 is a longitudinal vertical section taken along the line 3 3 in Fig. 2 and showing the front and rear grate bars in elevation.

Fig. 4 is a Vertical section through one of the dump grates taken along the line 4 4 in Fig. 6.

Fig. 5 is an end elevation of one of the shaker grates taken along the line 5 5 in Fig. 6.

Fig. 6 is a side elevation of one of the shaker grates shown in Fig. 5.

, Fig. 7 is a fragmentary enlarged section taken along the line 1 1 in Fig. 4.

Fig. 8 is a side elevation of one of the skids used between each lateral dump grate and its adjacent bearing grate.

Fig. 9 is a plan of Fig. 8.

Similar numerals refer to similar throughout the several views.

parts Bearing grate unit Referring in detail to the drawings, there is shown the front wall I0, the bridge wall II, and side wall I2 of the furnace or boiler setting, into which my grate bars are to be installed.

Referring particularly to my invention, Same will be seen to consist of the bed rails I3 which are preferably in the form of channels and spaced from each other to receive one complete unit of dumping grates. On the top side of each member I 3 is placed a plate I4, which acts as a support for the side wall seals I5 and 3I which close the space between the outside of the members I3 and the side wall I2. Disposed along the intermediate portions of the plates I4 are the bearing grates I3, having an opening i1 formed therein to receive the bushing I3, or other form of bearing, which is held in place by means of the pin I3 extending into the opening i1. The bearing grates i3 are held in place on the members I3 by means of the bolts 2S.

The member i6 has an air passageway 21 formed therein which cools the bearing and affords a means of communication for air passing from the under grate space 28 through the air ports 29 to the combustion. Air enters the member I3 through the side ports 3l). A refractory material 3l is filled in between the bearing grate I6 and the wall I2 and its top surface 32 is preferably inclined as shown.

Dumpingl grottey unit Each section of dumping grates consists of a channel` shaped dumping grate bearing bar 2i within the ends of which are bolted the blocks 22, from the ends of which project the tllnllQllS- CII 23 which journal in the bushing I8. Foreign substances are prevented from entering the bearing surfaces by means of the collar 24 on the inner side of the bearing I 6, and the cover plate 25 on the outer side of the bearing IS. Of course, this applies only to the bearing nearer to the outer wall` l2. The intermediate bearings 26 are duplicates of the bearings I6 but of course use two of the collars 24 as the trunnions 23 extend into those bearings from both ends. Each dumping grate unit consists generally of a fiat grate surface 33, which is somewhat rectangular in form and has formed on the top side thereof the plurality of ribs 34 through the bases of which are formed the horizontal slots 35 which communicate through the downwardly extending portion 36 with the under side of the grate surface 33. Depending from the nat top 33 are the vertical sides 31 having a groove 38 formed along the length thereof except at the extreme ends, which are closed by the ribs 39. The lower side of each groove 33 is inclined as shown to receive the sealing rods 4I. The faces 4I! are opposite and slope downwardly toward each other and the rods 4! simply settle down to a seat on the two faces 4Q. The rods 4I may be of any length but in practice are about one half an inch in diameter and six inches in length. At one end of the ribs 34 is disposed the transverse rib 42, and along the length thereof one or more intermediate ribs 43, the purpose of which is to prevent all of the ashes from dumping, leaving a blanket of ash over the dump grates when the dump grates are returnedL to their horizontal or burning position.

It is desirable to provide the notches 44 in the ribs 42 and 43 and the ribs 34 are provided with the notches 45 for expansion purposes. Extending downwardly from the end of the grate surface 33 just outside of the rib 42 is the inclined wall 43, which terminates in a horizontal ledge 41 which forms a support for the next adjacent grate member when in a` burning position.

At the opposite end of the grate surface 33 is formed the under cut face 48, which terminates in the rounded shoulder 43 adapted to rest on the ledge 41 of the next adjacent grate member.

Extending downwardly from the grate surface 33 are the webs 50 which are united at intermediate points by the transverse webs4 5l, which are spaced far enough apart to receive the bar 2l, it being preferable to provide bosses 52 at each corner of each web 5I for seating purposes if desired. Projecting below the edge 53 is a pivot pin 54 which is integral with the central rib 55, which extends along the length of the shaker grate section. The pin 54 occupies a corresponding hole. in the top of the bar 2|.

It will be noted that the air passing upwardly through the ports 33 will be turned horizontally along the surface 33 and meet the corresponding air stream from the opposite port 35, setting up a dispersing and diffusing action, which is conducive to uniform combustion over the area of the fuel bed.

Skirt for dumping grates It is sometimes desirable to provide a skirt 53 whose upper edge 51 extends over the side of a marginal grate as shown in Fig. 4, while its projecting lug 58 is a counterpart of the shoulder 49 and its lug 59 is a counterpart of the ledge 41. The member is provided with a cut away portion 60 to receive the channel 2l. An angular foot BI projects laterally from the member 53 and bears yagainst'the si'de web 50 and holds the member 56 in a vertical plane. Y

VA shoulder 62 is formed on the same side of the member 56 as is the foot 6|, and is adapted to engage the under edge of the shaker grate 53 as shown in Fig. 4. "The purpose of the skirt 56 is to prevent pieces of clinker from getting underneath the dump grates and pinching between the dump grates and the bearing grates, thereby making vitfdifdcult to close the dump grates after they have been placed in an open position.

Rear bearing grate units Mounted across the bed rails I3 near the bridge Wall I I is a rear grate supporting rail 63 which is secured to the rails I3 by means of the bolts t4.

Each rear'grate unit has a sloping surface 65 which terminates at its lower end in the horizontal section 66,-which is substantially level with the top of the bearing grate I6. The portions 65 and A66 are provided with air outlet ports 61'. From the horizontal 'portion 66 the rear grate slopes downwardly along Ithe faces 68, which is substantially parallel with the face 69 of the bearing grates I6 and spaced therefrom by means ofthe horizontal lug 10, the space between the faces 68 and 69 and above the lug 1I) being filled with refractory or ash, Whereas those portions of the rear grates in alignment with the shaker grates employ the lugs 19 as stops for the shoulder 49 thereof. Side wings 1I extend downwardly along the front of the rail 63 while the lugs 12 engage the upper portion of the rear side of the rail 63. An asbestos strip 13 is placed above the lug 12 between the rear grate units and .the bridge wall II. The space above the strip 13 is lled with a refractory 14.

Front grate um'ts is employed in the wings 1I of the rear grates and r for the same purpose. Ihe front edge of the front grate is provided with a channel sha-ped lug 8| upon which rests the strip 82 of asbestos, upon which is placed the filler 83 of refractory material,

which extends to the front wall I0. The purpose i of the channel is for a special form of casting em- .ployed in front of the fire door, the .details of which will not be described here as they have no bearing on the present application. It will be understood that the front and rear grates are stationary.

Dumping mechanism For convenience in rocking .the dumping grate unit, is provided a cylinder 84 which is pivotly mounted on the pin 85 and is provided with a piston rod 88 which is connected to the forked end 81 of the rock lever 88, which is secured to .the bar 2l by means of the bolts 89. The link 90 extends to duplicate levers 88A which are not shown in these drawings, but it will be understood that as many of these must be employed as is necessary to occupy the space between the front and rear grates. A fluid pressure is admitted to and released from the cylinder 84 in any convenient formed around the base of the pin 54, the pur-pose of which is -tov enable the relatively large dumping grate unit to float into a position of maximum air seal, and also facilitating the assembly of the grate. y V

It will be seen from the foregoing that in addition to the structural advantages 'above de-f scribed, grates so constructed'are self-protecting due to the layer of ash Ywhich must remain on lthe grates even after they are dumped, which condition not only protects the grate members but also insures a more uniform diffusionA of air over the entire surface anda better burning conditionv over the entire grate area. Special attention i's drawn to the sealing rods 4I, each of which is supported by the faces 48 of adjacent shaker grate sections, not only adapting the sections to 'each other within the limits of the spacings" determined by the pins- 54 but also affording a sealfto prevent air from passing forwardly between the sections or ashes from passing downwardlybetween the sections. f

With further reference to Fig. 4 of the draw# ings, it will be noted that the air passing upwardvly through the ports 36 impinges against the top of the slots 35, .carrying the heat away from the only portion of the grates in direct contact with the burning fuel and then passing laterally along the surface 33 until it meets a corresponding stream from the opposite port 35, producing a diffusing action.

While I have thus illustrated and described my invention, it is not my intention to be limited to this precise form, but intend that it shall cover all such forms and modifications thereof as fall fairly within the appended claims.

I claim:

l. A grate of the class described Icharacterized by having its surface broken longitudinally and laterally into a plurality of grate sections and characterized by having each of said sections independently `and pivotally mounted, and self-adjusting rods for sealing the clearance spaces between said sections,

2. I n a grate of the class described, a combination o-f a transverse grate supporting bar for a furnace, supported at opposite ends thereof and having means for rocking same, together with a plurality of gratevsections disposed along the upper side of said bar, each of said sections being characterized by having an inverted U-shaped slot formed under same adapted to straddle said bar, each of said sections having a centering pin extending into said bar and having means adjacent to said pins for spacing said grate bar and said supporting bar. y

3. A dump grate section consisting of a rectangular plate having a forked projection on the under side thereof adapted to receive a grate sup- Aport; a dowel pin projecting from said plate into within vsaid grooves, one end of said plate being inclined downwardly and then horizontally to form a ledge and the other end of said plate extending downwardly to form a shoulder approximately the same distance from the top of said plate as is said ledge, and a plurality of transverse ribs connecting said first mentioned ribs adapted to prevent the complete dumping of ashes from the top side of said plate when said plate is inclined for dumping purposes.

4. The grate section as defined in claim 3, characterized by having .a forked projection on the under side thereof, a channel bar a plurality of said sections mounted side by side on said channel shaped bar, said channel bar having a trunnion secured at each end thereof, a bearing grate at each end of said bar support having a bushing therein adapted to receive said trunnions and means for dissipating the flow of heat downwardly from said grate to said bearings.

5. A skirt for dumping gratos consisting of a at vertical member having a notch formed along the middle thereof for the reception of a grate supporting channel, one end of said skirt having an arcuate edge and the other end of said skirt having a ledge formed at its outermost end adapted to stop-against an adjacent member.

6. A grate bar for supporting a bed of fuel, characterized by having grooves formed along the side thereof, the lower portions of the grooves being inclined outwardly, and a sealing rod in each groove, adapted to rest upon the inclined faces of the grooves in adjacent sections.

7. In an apparatus of the class described, the combination of a horizontal channel member constituting a dump grate supporting bar, having dowel holes formed along one leg thereof, a bearing grate disposed at each end of said bar, a trunnion secured to each end of said bar in said grate, a plurality of removable dump grate sections mounted on said supporting bar, each of said dump grates having forked extensions on the under side thereof adapted to stradd-le said bar, each of said sections having a dowel pin projecting downwardly therefrom adapted to register with the holes in said bar, the adjacent sides of said dump grate sections having recesses formed therein, each recess having a sealing rod disposed therein, the endmost dump grate sections having skirts adapted t0 extend downwardly along side of the bearing sections when said dump grates are inclined for the purpose of preventing the lodgment of obstructions therebetween.

RICHARD C. WRIGHT.

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