US2608958A - Grate bar - Google Patents

Description

Sept. 2,1952 c. M. HAZELTON GRATE BAR 2 SHEETSSHEET 1 Filed Aug. 20, 1949 Enventor 1" ill (/MRLEJ M. HHZEI. To/v v I a :Qfiwm Gttomeg S p 1952 c. M. HAZELTON 2,608,958

GRATE BAR Filed Aug. 20, 1949 2 SHEETS-SHEET 2 3nneutor 0/14/5155 N. HHZELTO/Y Ciitomeg Patented Sept. 2, 1952 UNITED STATES PATENT OFFICE This invention relates to water-cooled grates for use in furnaces and it has reference more particularly to water-cooled grates, comprising a succession of likegrate bars that are fixed in juxtaposition to form a supporting surface for a fuel bed, and wherein water pipes are contained for circulation of water as a means for keeping the temperature of the grate below thatwhichis detrimental to the life and effectiveness of the bar. ihe present invention may be considered to be an improvement upon grate bars of those kinds typified by U. S. Patents issued to John T. Tawlks, under Nos. 1,775,790 and 1,852,492.

It is the principal object of this invention to provide a water cooled grate embodying novel features of design, both with respectto the individual bars and the water pipes contained therein, whereby maximum effectiveness for cooling by water and air is obtained; whereby the flow of the air through the grate will be increased; wherein the removal and replacement of the parts of the individual bars may be accomplished without disturbing the setting of other bars; that minimizes the number of header connections for boiler feed water; that facilitates the flow of air through the bars to the fired bed and furnace and promotes self-cleaning of the bars; whereby weight is materially reduced and life of the grate is materially lengthened.

It is also an object of this invention to provide a grate bar comprising a base section and top or cover section with adjacent surfaces channeled for the enclosing of a section or coil of pipe through which water as a cooling medium may be circulated; the arrangement of channels being such that when all base sections of a grate have been set in place, the pipe coils therefor, as a continuous conduit, may be laid in-place and then covered by applying the top sections to the bars.

It is a further object of my invention to obtain more contact surface of the water pipes, and increased effectiveness of the cooling medium by use of pipes that are somewhat flattened in. a horizontal direction.

Further objects of my invention reside in the details of construction of the bars and pipe coils, particularly in the manner in which the coils are disposed in the bars as a continuous conduit.

It is also an object of the invention to provide grate bars of the present character for containing water pipes therein and having removable top sections that are held in place by bolts that are removable from the top of the grate, and wherein it is not required that a orkman should enter the furnacebelow the grate for the removal of a bolt or for the repair or replacement of any part of the grate.

Yet another object is to so design the air passages through the bars that a better flow of air is provided and the bars will be self-cleaningoi ashes and will afford a flat easily cleaned surface for the fuel bed.

Still further objects and advantages of my invention are to be found in the details of construction of the various parts of the bar and in the combination and relationship of parts as will hereinafter be described.

In accomplishing theseand other objects of the invention, I have provided the improved details of construction, the preferred forms of which are illustrated in the accompanying drawings, wherem-- Fig. l is a perspective View of a portion of a grate comprising water-cooled bars embodying the improvements of the present invention there- Fig. 2 is a top view of one of the grate bars, with one end portion of the top section thereof cut away, to show the channeled top surface of the lower section; the water pipe not being shown in this view.

Fig. 3 is atop view of the base section of a bar,

with a coil or section of water pipe disposed thereon. V

Fig. 4 is a side elevation of one of the bars, one half being shown incentral, longitudinal section.

Fig. 5 is a cross-section of the bar taken substantially on line 5-5 in Fig. 4.

Fig. 6 is a cross-section taken on line 6-6 in Fig. 4, showing the cross-sectional shape of the water pipe and the disposition of the bafiie.

Fig. 7 is an end elevation of one of the bars.

Fig. 8 is a-perspective view, showing a detail of construction at the under side of the bar.

Referring more in detail to the drawings- In Fig. l, I have shown a portion of a furnace and grate; the latter comprising bars embodying the improvements of the present invention therein; the top section of the near bar being removed to show the disposition of the pipe coil in the bar.

Each grate bar is of elongated, rectangular form ,as shown in Fig.2, and comprises a base or bottom section, designated in its entirety by numeral I0, and a top or cover section, designated in its entirety by numeral l2. These two sections, in plan, have identical dimensions and are assembled by placing section [2 upon and in regis- 'tration with section Hi, and then securing the sections together by means of a plurality of bolts 13 applied through registering openings [4 formed in the longitudinal edge portions of the sections as shown in Figs. 2 and 5.

The bottom section ID of the bar, as noted best in Fig. 3, comprises a rectangular body portion, substantially uniform in thickness from endto end and formed along its longitudinal center line with a through slot or opening l5 of substantial width. This slot terminates at its opposite ends, at short distances from the ends of the bar. It provides for the passage of air from beneath the grate to the fuel bed as supported on the bar, and also for disposal of ashes from the grate to the ash pit below.

Cast integrally with the bar section ill, at its underside and spanning the longitudinal slot [5 at spaced intervals therealong as seen in Figs. 3 and 4, are downwardly directed ribs or flanges it, which support a longitudinally extending baiile I9. This baflle is cast integrally with the bar section as noted best by reference to Figs. 4 and 6, and it extends lengthwise of the bar in its central, longitudinal plane, and its top edge is spaced somewhat below the bottom surface of the bar and extending to the full length of the slot l5. In this position the baille serves to defiect air flowing to the grate through the ash pit, upwardly into the slot and through the distributing slots or passages of thejtop section l2 of the bar presently described. Medially of the opposite ends of the bar section H3, the space between adjacent cross ribs I8 is closed by a cross web 20, shown in Figs. 3 and 5, to give strength to the bar at this particular location where it is somewhat weakened by reason of the cross channel formed therein for the end portion of the pipe coil.

Formed in the top surface of the bar section I 2 is a continuous channel for containing a section of a pipe for the circulation of the grate cooling medium. This channel is shown in Fig. 3 to lead from a starting point at one side edge of the bar designated at 25a, which is midway of the ends of the bar, into and then along the piece adjacent the longitudinal slot l5 to one end portion thereof, it then turns gradually, as at 25?), to the opposite side of the piece and continues therealong adjacent the slot l5 into the opposite end portion and there makes a halfturn as at 25c, and continues along the bar to near the starting point where it turns inwardly, as at 25d, into the slot [5 above the web 20. Directly opposite the point 25d, a channel 251: is f ormed transversely in the bar; this channel being extended in depth below the depth of the longitudinal channel as willbe understood by reference to Fig. 5. It is shown also in Fig. 5 that the depth of the channel 25, at its entrance point 25a is of increased depth for a purpose presently apparent.

Associated with each grate bar is a looped section of water pipe 30, one complete loop being shown in Fig. 3. Each section is bent so that it may be laid in the bar channel 25. The opposite ends portions, 30a and 30b, of the pipe section are downwardly offset from the plane of the horizontal loop, as shown in Fig. 5, so that the end portion 352), which is turned inwardly and extends across the bar, will pass beneath that straight length of the pipe that extends the length of the bar, where it continues into'the end of the pipe coil of the next adjacent bar. It is preferred that the pipe coils be in one continuou pipe and that sleeves 35, as applied in Fig. 5, be used to join the ends of the water pipe to the boiler circulation or with other water supply system. Preferably a water pipe of copper is used because of its ready adaptability and high heat transmission.

The top section l2 of the grate bar comprises a flat body section that is designed to rest flatly upon the top surface of its complemental base section IE3. It is formed in its under side in registration with the channel 25 of the base section, with a channel 36 for receiving the top half of the pipe coil therein, as best shown in Figs. 5 and 6; the pipe being flattened to an oval crosssectional form for a purpose presently explained.

The top section 12 of the grate bar is formed with a succession of angularly directed cross slots 40, opening to the side surfaces of the bar, and downwardly flared in cross-section as shown in Fig. 4. These slots Gil extend across and open directly into the slot l5 that is formed through the bar l0, and thus provide for an upflow of air to the top surface of the grate and for an easy downward passage of ashes through the grates. The opposite end portions of the section I2 and the bar-like portions thereof that are between the cross-slots 40 are united in a rigid, unitary member by integral, continuous bar-like portions designated in Figs. '3 and 4 by reference numerals Ho and 12b. These bar-like portions which provide open spaces [59: between them are flush with the bottom surface of section [2 and register directly upon the longitudinal portions Illa and lllb of section H] which are at opposite sides of the slot 15 therein. The bar-like parts 12a and [21) have a vertical thickness equal to about one-half the vertical thickness of the section I2 and, as exposed in the cross-slots have their top surfaces transversely arched so as to not retain ashes thereon. The transversely slotted portion of section I2 extends the full length of the slot [5 in thesection 10..

It is shown in Figs. 1, 2 and 3, that the longitudinal edge portions of the bar section I0 is formed with notches 50 that register with the end portions of the slots 40 in the top section to provide for passage of air to the furnace therethrough in addition to that supplied through the slots I5. These passages also provide for the passing of ashes to the ash pit.

To build a grate in a furnace, the base sections of the grate bars are first placed edge to edge, as in Fig. 1; being supported at their ends on shelves formed in the furnace walls 6il6ll, as shown in Fig. 4. After the base sections have been positioned, the water pipe as a continuous piece in a succession of loops is placed thereon, and connected at its ends in the boiler system.

After the water pipe has been placed on the bottom sections, the top sections of the bars are placed in position, and are then secured by applying the bolts l3.

It is a feature of this invention that the bolts are equipped with oblong nuts I32: as shown in Fig. 8 and that the holes [4 in the bar sections are oblong for passing the nuts therethrough. The manner of applying the bolts, is to first apply a nut to the bolt, then project the nut and bolt down through registering holes in the bar sections, and. then to tighten the bolt into the nut. The nut in this case, engages against lugs 65 on the under side of the base section of the bar and is held against turning. It is the intent that the head of the bolt be quite thin to avoid obstruction of the top surface of the grate.

Those portions of the channels which contain the opposite end portions of the pipe coils and the laterally turned end portions are given extra transverse width in order to allow for a certain amount of expansion and contraction of the coil. This extra width is shown in Fig. 3.

In briefly summarizing the advantages residing in the present construction, it can be stated that the horizontally flattened condition of the pipe coils makes possible a materially greater contact area between bar elements and pipe surface, that results in a correspondingly increased heat transmission. The use of copper tubing in making the coils not only makes it possible to easily and quickly shape the coils but also materially minimizes the number of fittings and headers necessary. Weight in the grate bars is reduced to about two-thirds that ordinarily required and installation costs are also materially decreased.

The design of the bar, with the single centrally located bafile and the relatively large central air passage, materially increases the flow of air through the grate; this being due to the guiding and deflecting affect of the baiile.

Grates so constructed, under reasonable and average operating conditions, will last indefinitely. They may be made in various sizes, and to include various numbers of bars. A single, continuous water circulating pipe is preferable but this may be made of one or more sections if such is found desirable.

Having thus described my invention, what I claim as new therein and desire to secure by Letters Patent is-- 1. A watercooled furnace grate comprising a plurality of grate bars mounted in juxtaposition; each bar comprising a flat base section and a fiat top section disposed thereon, and a continuous pipe for circulation of the cooling medium therein, formed into a succession of loops disposed in the grate between the base and top sections of the said bars; each of said base sections being formed therethrough with a central, longitudinal air slot extending substantially to the full length of the bar and there being a channel in the top surface of said section, leading thereinto at one side of the bar and continuing entirely about the said air slot and opening at its other end to the oppo- I lower surface of the said section, in the central longitudinal plane of the slot therein for the deflection of air currents into the bar slot.

3. A grate as recited in claim 1 wherein the said registering channels of the upper and lower sections open to opposite sides of the bar medially of its ends to receive the said continuous pipe, forming the said loops, said pipe being substantially flattened in a horizontal direction and said channels, as formed in the sections of the bar, to receive the pipe, being shaped to conform to the flattened form of the pipe.

4. A grate as recited in claim 1 wherein the lower sections of the bars are formed along opposite side edges with vertical air channels thereacross opening into the ends of the transverse slots of the top sections, and wherein said vertical edge channels of adjacent bars in the grate are in registration.

CHARLES M. HAZELTON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 656,059 Thurell Aug. 14, 1900 916,609 Schmidt Mar. 30, 1909 1,026,030 Goreau May 14, 1912 1,775,790 Tawlks Sept, 16, 1930 1,796,868 Hagedorn May 17, 1931 1,852,492 Tawlks Apr. 5, 1932 2,242,629 Thoke et al May 20, 1941

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