US1833952A - Furnace grate - Google Patents

Description

1, 1931. E. B. PRIEQ'BE ET AL 1,833,952

FURNACE GRATE Original Filed Jurie 25, 1921 s Sheets-Sheet 1 Dec. 1, 1931. B. PRIEBE ET AL FURNACE GRATE Original Filed June 25, 1921 3 Sheets-Sheet 2 M243 &CM

Dec. 1, 1931. E. B. PRIEBE ET AL 1,833,952.

I FURNACE GRATE I Original F'iled June 25, 1921 3 Sheets-Sheet 3 3 wve'wtoag W k 9mm T. W %11 duo M42135 ra mmd KMWI.

Patented Dec. 1, 1931 UNITED STATES ERNEST B. PRIEBE, OF RICHMOND HILL,

NEW" YORK, AND DANIEL r. MINER, or

PROVIDENCE, RHODE ISLAND, ASSIGNORS, BY DIRECT AND MESNE ASSIGNMENTS, T0 FURNACE ENGINEERING COMPANSLINQ, OF NEW YORK, N; Y., CORPORATION 5 if OF NEW YORK FURNACE GRATE 7 Original application filed June 25, 1921, Serial No. 480,394. Divided and this application filed Apri14,

1927. Serial no. 181,014.

This invention is, a novel furnace grate adapted for use in connection with automatic stokers and being herein illustrated in connection with an underfeed stoker for aboiler furnace- The general objects of the present invention are to afford a furnace grate and stoker of greater efliciency in operation and superior strength and durability in construction. A particular object is to minimize the difficulty of the sifting of ashes through the grate into the wind box, which has been quite pronounced in certain types of stokers. Another object is to improve the operation and efficiency of the furnace by perfecting the manner and means of air distribution. Another specific object is to afford a novel and advantageous system of twyers for afurnace grate. Other and further advantages of the present invention will be made to appear in the hereinafter following description of one form of embodiment thereof or will be apparent to those skilled in the art.

To the accomplishment of the objectsand advantages mentioned the present invention consists in the novel furnace grate and stoker herein described and illustrated and the novel features of arrangement, combination, construction and operation thereof.

In the accompanying drawings forming a part hereof Fig. 1 is a longitudinal section, taken on the line 11 of Fig. 2, of a furnace, stoker and grate embodying the principles of the present invention. r

Fig. 2 is a transverse section taken on the line 2-2 of Fig. 1, looking toward the rear or bridge wall of the furnace.

Fig. 3 is a perspective view showing the construction and arrangement of the different kinds of'members constituting the main grate.

Fig. 4 is a partial vertical section taken at or beneath the position of the line appearing on Fig. 3. r

This application is a division of our application for furnace grates, filed June 25, 1921, Serial No. 480,394, being based upona por tion of the original disclosure of said application, the same having now resulted in United States Patent No. 1,633,418, granted June 21, 1927 without containing the complete original disclosure. 4 Jv Although the invention might be applied PATENT owes to furnaces, stokers and grates of; various kinds and types we have'merelyshown the same applied to the kind .offurnace embodys ing what is known in the trade as a Type E stoker. The so-called Type E stoker is used more'especially for boilers of smaller sizes and usually there is but one retort to thefurnace, although we wishit understood that the single retort shown in Figs. 1 and2 could be duplicated, or a number of retorts maintained beneath a single boiler. Certainof the devices herein shown, including the stoker actuating mechanism in front of the furnace, are not herein claimed to benovel, but indeed are well known constructions not requiring detailed description; for example, the

exemplified in the patent of Wood No. 818, Y

010 of April 17th, 1906.

Referring to the details of the herein illustrated embodiment of the present invention, the combustion chamber of; the furnace ,is shown as bounded by theusual wall 7 at the front, bridge wall 8 at the rear and side walls 9,9,and at the upper part of the combustion chamber is indicated a portion of a water tube boiler 10. The entire structure is shown resting upon concrete foundations 11 within which isprovided, for each retort, --an' air duct -12 which serves to convey forced draft,

. controlled by damper 13, into the passage 14:

constitutingan air box directly bene'athth'e retort and supplying air to the two opposite wind boxes beneath the grates, as will be described.

Above thegratesjisshown' the fuel bed'15 and while the present invention might be applied to a furnace'having a fuel bed maintained in different ways, for example, by overfeed, it is herein" shown maintained by underfeed, as is customary with the illustrated type of grate. An exterior fuel hopper 16 delivers fuel dir'ectly in front of a reciprocating ram 17 which at each advance stroke thrusts a designated amount of fuel into the lower part of the fuel bed in the furnace. The ram 17 is rigidly connected with a reciprocating crosshead 18 actuated through a connecting rod. 19 by a piston 20 within" a cylinder-21" supplied with steam by a pipe 22, the operation of these parts being regulatedby mechanism 23,. the details of V which are well known and form no partof the present invention.

' The 'fuel thrust into the furnace by the ram 17 passes through the expandingthroat 24 into the retort 25. The fuel passes rearwardthrough: the length of-theretort and also piles up and spills over laterally at both sides forming a symmetrical fuel bed, as shown in'Fig. 2, the fuel travelling down. the inclined grates at the two sides and finally, when'burnedout, being discharged bythe dumping grates 26 into the ash pits 27. The general course of the fuel having been thus explained the construction of the retort, the grates, the wind boxes and the aircontrol will now be described. r

The retort has its bottom formed by a plate'29 which as usual in this type of fur nace is arranged to reciprocate rearwardl-y and forwardly, the side edges of the plate '29 -resting' upon ribs 30 formed on the wind fuel support-atian'd'tothe rear ofthe throat.

The ram 17 is rigidly; connected upon the plate 32 and therebyreceives its reciprocat'ion. Th'erear extremity of the bottom plate 29 slides beneathan inclined plate 33 forming the. rear end' of the retort;

Iirthis symmetrical design of furnace the retort stands between two similar grates which are air supplied and which,therefore,

in efiect form theupper sidesoftwo opposite similarchambers or wind boxes-r These will now be describedi Owin'g to'the preferred flaring shape of" the'retort 25" each-of the "wind boxes may be considered as having a ridgeor peak and two slopes,*an abrupt slope from the ridgeon the retort side, comprisingtwyer members, and a more gradual slope or inclineat' the-outer side, constituting the ra v 'The inner side of each wind box is' pref 'e'r'ablya vertical metal wall, the lower part of the retort.

ofw-hich forms a wall of-the airbox 14 and the upper' part 36 of fwhich forms a side wall Resting on the walls 36 are the-sloping twyer members 37 consisting of up'standihg members in face contact, with grooved edges affording tapered apertures discharging" into the retort; twyer members rest a series of cap plates'38 Above these which form the ridge or peak of the grate. At the other side of the cap plates extends at a downward slant the main grate 39 at each side. The lower end of the gratesrest:

upon" bearing plates 41 at the right and left. Belowthe bearing plates are downwardly extending walls 453, and therebelow diagonal walls 14: connecting with the bottomwalls 455, which extend toward the center and are united with the first mentioned-upright wall portions bounding the air box.

Each wind box is shown with a partition 46 separating it into two chambers connected byan'opening controlledby a damper 470perated by an external handle 4-8. Each wall portion: 35: has a. sliding damper 49 operable from. an-exterior'handle 50 through a slidingrod 51.v The: course of the air is thus through the main. airduct 12, the .air box 14, the dampers 49: into the wind box and partially'through the dampers 5L7 and upwardly from the. windbox through all portions of the grate into the fuel bedr The wind. box: construction is held steady and; rigid by its support and attachment upon aportion: of the concrete foundation ll. The upright wall 36 has attached to it'two or morethree-armed brackets 53. Unearm of this'bracket is used. to secure in" place the twyer members 37 by means of a rod 5r passe ing through the bracket arms and perfcrat ed extensions-f the twyers. Similarly" a second; arm of the bracket "is used togive support to the' stationary bars of the grate 39 ort 40, a' rod 55 extending through the arms and extensionsof the bars.

The cap plates 38 are. of novel form seen. in all: the figures. Each cap plate is beveled at its front end ivin an inclined.

overhang 59 which fits against a correspondbe' clear' from Fig. 1'; e prefer that the cap plate should be constructed with grooves 60 forming apertures at the undersides of the plates for'delivering'air laterally in both directions, that is, into the retort and above the main' grate. The cap plates are also shown provided with ribs 61 which are arranged longitudinally,.these serving to divide "IDS mg incline of the adjacent cap plate as will the surface of the cap plates into concave P r areas which we find to be of substantial ad- This gives a decided protection against the deterioration of the plates and substantially prolongs the life of the cap plates. V The cap plates are shown locked and held in place by means of dovetail extensions,

such as tofit between the inclined twyer members 37 and the, upper edges of the stationary bars of the grates 39.

Coming'now'to-the main grates, each of these comprises aiseriesof inclined grate bars arranged adjacent to each other extending at right angles to the length of the retorts and, of course, longitudinally to the downward advancing travel of the fuel, which passes laterally from the retort toward the dumping grates near the opposite side Walls. These side by side grate bars are shown as stepped, that is each one of them is formed with a series of horizontal surfaces one beneath another so that the advancing fuel bed passes downwardly step by step toward the discharge. Alternate grate bars reciprocate longitudinally of the direction of the fuel feed relatively to the remaining bars which are preferably stationary or non-reciprocating. This construction is shown in front elevation in Fig. 2, which shows a stationary bar at the right side and a reciprocating one at the left. Fig. 3 shows several adjacent bars in perspective, partly broken away, and Fig. 4: is a vertical cross section of several of them. The alternate stationary grate bars 65 have the movable grate bars between them and the two are of slightly different construction for a purpose which will appear. Each stationary grate bar has its topmost portion, which may be termed the top piece or top step 66, of the combined width of two adjacent grate bars. Thus the entire top of this system of grate bars consists of stationary members 65 and these are so shaped and arranged as to engage and lock with the dovetail of the cap pieces 38, already referred to.

The stationary grate bar 65, below its flat top step 66 is formed with integral second, third, etc. steps 67 to 72, a total of 7, at successively lower levels. The grate bar has a substantial vertical dimension below each step and this downward extension is provided with several horizontal ribs or tongues 7 3, extending to the right in Figs. 3 and 4t, and 74: extending to the left, staggered or offset relatively to the ribs 73. These ribs and the recesses between them are for the purpose of engaging similar ribs and recesses on the reciprocating grate bars giving a com pact interfitting system, sufliciently loose fitting, however, to permit the forced draft of air to pass horizontally between the grate bars for discharge into the fuel at each level of the grate.

Each of the movable grate bars 75 is formed with a top step 76. This is not at the same level with the top sections of the stationary bars, but is accommodated between the latter and the uppermost rib 7 3, as clearlyshown in Figs. 8 and 4, the upper end of the movable bars thus receiving support and guidance for their reciprocating movements. The succeeding lower steps 77, 78, etc. of the movable grate bars are the same levels as the corresponding steps 67, 68, etc. of the stationary bars; and the depending portion below each step of the movable bar is provided with ribs or flanges831and ribs 8a which partake in the interengaging structure and function alreadymentioned. j 1

This construction of'grate gives very effective air supply to the fuel bed and yet is 1 i such as to practically prevent the possibility of siftings passinginto the wind boxes. The air outlets are horizontal and there would be no tendency for ashes, etc. to pass inwardly toward the air supply. At the same time the air supply is ample and is delivered in an effective direction and with thorough distribution beneath the entire area of the fuel bed. 3

-The reciprocating or ments of the grate bars 75 are effected through "a connecting rod 85 actuated'by'a rock arm oscillating move- 86 or a rock shaft 87 which is worked auto- I matically under control of the timing mech- V anism 23. a l

The illustrated features of the present :invention, involving a certain amount I of looseness and play between the different grate bars, prevents any damage from expansion and contraction of the metal; the structure has an elasticity orself yielding'quality which takes care of the difficulties frequently involved in the expansion of the metal. 7 Another andvery important advantage of this V invention is the protection of the grate bars by maintaining them relatively cool. This is a due to the mode of air travel, which passes horizontally through the spaces betweenthe inclined grate bars and therefore has an extended length of travel in contact with the plied more eficiently and completely than in a different arrangement, andthe heat which It will thus be seen that we have described a furnace grate embodying the principles and attaining the objects and advantages of the present invention, Since many matters of arrangement, combination; design and detail may be variously modified without departing from the principles involved, it is' not intended to limit the invention to such matters except in so far asspecified in the appended claims. 7 i

What is claimed is:

1. In a furnace having a central fuel retort and a pair 'of oppositely inclined grates one along eachof the lateral'sidesof the retort, the retort discharging laterally over such sides upon such grates, each grate composed of inclined gratebars (65, 75) having stepped fuel supporting top sides, loosely interfitting to afford narrow air passages delivering into the fuel bed, and alternate grate bars (65) being stationary and having wide topmost portions alined longitudinally with -metal. The cooling effect is therefore apis produced at the outer surface of the grate 1,

ins

ilo

'respect to the retort, the remaining bars (7 5) being movable and terminating short of such topmost portions, and connections for methodically reciprocating'the movable bars.

2.-In a furnace havlng a central fuel retort and a pair of. oppositely inclined grates one along each of the lateral sides of the retort, the retort discharging laterally over suchsidesupon such grates, each grate com- 7 posed of alternating inclined grate bars 'of two shapes each having fuel supporting steps, the grate bars'of one shape having wide top portions in horizontal longitudinal alinement with respect to the retort,and those of 1 5 the other shape terminating below such alined portions, and means for reciprocating the bars of'one shape relatively to those of i the other.

3. A furnace as'in claim 2 and wherein are cap plates extending across from the tops of the retort sides tothe top portions of the grate bars of'the first shape and interlocked therewith.

4. In a furnace having a centralfuel retort and a pair of oppositely inclined grates one along each of the lateral sides'of the retort, the retort'di'scharging laterally over such sides upon such grates, each grate composed of inclined grate bars having stepped fuel supportingtop sides, and loosely inter-' fitting to afford numerousnarrow and non-.

1 sifting air passa es delivering into the fuel signatures hereto.

bed, twyer members resting on the retort sides, and a series of separate removable cap pieces. overlying the tops of the twyer members and alternate grate bars and having underneath interlocking engagement with the top edges of both the twyer members and such alternate grate bars, and means for reciprocating the remaining grate bars.

In witness whereof, we have aflixed our ERNEST B. PRIEBE- DANIEL P. MINER.

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