US2695575A - Reciprocal grate for boilers and other heating units - Google Patents

Description

Nov. 30, 1954 L. F. GOUGH 2,695,575

RECIPROCAL GRATE FOR BOILERS AND OTHER HEATING UNITS Filed July 28. 1952 s Sheet s-Sheet 1 INVENTOR L. F. GOUGH Nov. 30, I954 RECIPROCAL CRATE FOR BOILERS AND OTHER HEATING UNITS 3 Sheets$heet 2 Filed July 28. 1952 lN vENToR LESLIE F. GOUGH %1%%%M Nov; 30, 1954 RECIPROCAL GRATE FOR BOILERS AND OTHER HEATING UNITS Filed July 28, 1952 3 Sheets-Sheet 3 j f-a 5 2% 25 24 o o o o o o 34 o O 0 INVENTUR 0 00060 \Zfi Luz Z EGOUGH Patented Nov. 30, 1:54

RECIPROCAL GRATE FOR BOILERSAND OTHER HEATING UNITS Leslie R Gough, La Salle,0ntal'i0, Canada Application July 28, 1952, Serial No. 301,197 2 Claims. (Cl. 110-38) ments used to provide automatic firing of vapor generators such as steam boilers.

It has long been known to supply solid fuel particles to the fire-pot of a heat generating system by means of a, slowly moving chain whereupon the fuel burns progressively throughout its exposed mass as it. is moved across a grate surface toward a clinker state at or near the rearward bulkhead of the fire-box,

In later adventures, the chain has been modified to carry grate members which in some cases overlap. and are arranged shingle-fashion with leading edges forming step-like surfaces which urge the fuel forward across the fire pot.

In a still later adventure, means have been devised to provide a reciprocal and pulse-like motion between adjacent and overlapping grate members with a view to breaking up and foraminating thefuel mass soas to extend the surfaces of attack presented to the combustion gases, and, at the same time pulse-like forward movement of the fuel masses at a predetermined rate. Such arrangements are most advantageous in connection with efforts to provide the highest possible combustion efliciency, and are particularly effective when applied to low grade fuels or to solid fuel particles which have been severely comminuted. An arrangement possessing these desirable advantages is described and claimed in U. S. patent specification No. 2,472,746 issued to the present applicant June 7, 1949.

One of the disadvantages which has plagued the users of prior art equipments resides in the fact that when a system of grate-bars is very closely coupled to an actuating mechanism, there is a very substantial transfer of heat energy from the necessarily very hot fuel-supporting and translating agency (such as a platform of grateto provide a positive and actuating means with resulting short useful life for the equipment.

In. a further aspect, when the grate-bars are firmly bound to the activating members, as for example by means of trunnions, swivels, clevises and the like, not only is the heat transfer to the actuating mechanism very large, but replacement of the grate members themselves is costly and frequent: in fact, in such equipments it is usually considered uneconomic to act otherwise than to scrap the Whole apparatus and install a complete new fuel translating system when heat has finally warped and/or burned vital portions of the equipment.

It is an object of the present invention to provide a means whereby the grate bars or members are loosely coupled to the actuating means but are none the less firmly maintained under positive control by the said actuating means.

It is a further object to provide an arrangement of the type indicated wherein the grate members are of simple design so that they can be manufactured at low unit cost and wherein the said design enables rapid replacement of heat-damaged sections without involving lengthy shut downs of the system.

It is a still further object to provide in combination, a grate member assembly comprising readily assembled and/or detached units which are associated with a rev material deterioration of the members of. the said mechanism.

In a further aspect again, it is an object of the invention to provide an actuating mechanism for a reciprocating grate-system wherein the. essential. driving agencies are of open and slender construction :50 as to provide a. minimum amount of mass within the wind-stream of the upedraf This form of construction, wherein concentrated heavy masses are avoided also furthers. the object of reducing the rate of heat flow into vital moving parts of the mechanism.

In the description generally and in the claims. with which the specification ends, the expression coupled is high initial temperature and control agencies; which are required to maintain a relatively low state of tempera. ture.

The invention broadly contemplates a reciprocating system including a pluhaving a slotted fin on for establishing limited motion of the said tracker-bars chanical stoker system therefor.

The description will be aided by reference tothe ac-. companying drawings wherein:

Fig. 1 represents an end view of a boiler showing the general positioning of the q Fig. 2 depicts, partly in section, a side view of the construction envisaged by Fig. 1.

Fig. 3 is a view looking down from the hot side to- Ward the cool side of the fire-box with one lay of grate members shown in position.

4 is a side view of the construction shown in Fig. 5 is a diagrammatic view of the mechanism and grate system of the invention.

Fig. 6 is a perspective concept of-Fig. 5, and,

Figs. 7, 8 and 9 depict details of a grate member.

Referring now to the figures: 1 depicts a boiler assembly to which the present invention has been fitted, 2 is a hopper to contain and supply the fuel, 3 is a fuel an 6, 8 are representative grate members in each transverse row: in action, 5 and 7 move in the same sense in one direction while 6 and 8 move similarly but in the reverse, direction. The fuel is pushed along platform 3 by pusher 4 and dribbles on to grate members, row 5. When row 5 moves to the left the fuel is dribbled oflf its leading edge onto grate 6 which is moving,

described, ward along row 6 whichis now moving to the left and the fuel dribbles off row 6 onto row 7. As the phase of motion is cyclically reversed at a predetermined rate, the fuel is inched along the grate surfaces toward a clinker platform 9 which may take the form of a dump grate.

The mechanism for actuating the respective rows of grate members comprises satellite shafts 10, 11, 12 and driven master shaft 13. These shafts are journalled in the side walls of the cool region of assembly, preferably in a self-contained framework independent of the fire-pot walls, and wholly below the grate surface.

Each of these shafts carries a captive tracker-bar, 14, 15, 16, 17 which is retained at a predetermined distance above its shaft by a plurality of spacing pillars 18. Alternate shafts also carry members 19, 20 similar to 18 but rigidly positioned 180 from 18 and arranged to receive, at their respective ends, the journalled terminations of a drive link 21: member 20 also provides journalled connection for a second drive link 23 and a corresponding member 18 on satellite shaft 10 provides journalled termination for the other end of drive-link 23, and also for one end of a drive-link 22 whose other end terminates in journalled relation with tracker-bar 16 and lies in a plane normal thereto.

A grate-member comprises (Figs. 7, 8, 9) and a depending fin 24 projecting downa foraminated casting 5 a wardly from one surface in a plane normal thereto, and

containing a slot 25 designated to engage a trackerbar 14, 15, 16 or 17 so as to provide a positive mechanical relationship between a said tracker bar and the grate member when the slot 25 and the bar are engaged. The slot provides a loosely journalled connection between a tracker bar and the grate member and constitutes the only coupling between the hot and cold sides of the system.

This loose relationship also provides a simple means for attaching and detaching grate members to and from the driving system without the aid of machine tools. It is not necessary to completely shut down the boiler in order to change a warped or burnt section of the fuel combustion surface nor does an operative need to work under intolerable temperature conditions in order to replace part or all of a grate platform.

The grate members seat over the tracker-bars and lie overlapping one another like shingles upon a roof but relying upon the slots 25 and the law of gravity to hold the fuel combustion platform in shape and position.

The foraminations of the grate members provide means 7 for access to the fuel of the up-draft and also provide simple means for grasping the member by a poker-end or the like so that grate-member replacements can be effected by an operator from outside the fire-box. From an inspection of Figs. 5 and 6 it will be eviden that when the piston rod 27 of motor cylinder 26 reciprocates and imparts through lever 28 a limited oscillatory angular motion to driven shaft 13, rows 5 and 7 will move together in the same direction under the influence of drive link 21, and rows 6 and 8 will move together in similar phases under control of link 22. These two links the positioning of group-driving link 23 the motion of shafts 10, 12 will be antihasal to that of shafts 11, 13.

Thus adjacent grate rows move toward and then away from one another during each cycle of the mechanism.

The showings on the drawings are not to be regarded as limiting as to scale. The pusher 4 may be arrange to have a longer thrust so as to function as both valve and injector. The length of thrust of piston rod 27 may be varied or .even made adjustable and its rate of reciprocation may be variably predetermined. The spacing between the tracker-bars and their associated shafts may be increased or decreased. It will be evident to those skilled in the art that different types of fuel will require specific rates of motion of the combustible material along the grate surface in order to achieve the highest combustion efficiency for a particular fuel composition. This may require corresponding modification of the dimensions depicted in order to predetermine the specific limits of excursion and translation rates of the respective grate member rows.

It will be evident that the different grate rows need not all have the same limits of excursion. For example, by positioning the shafts at respectively different levels and correspondingly lengthening or shortening the spacer members 18 on one shaft-tracker assembly with respect to another such assembly, the limits of reciprocation of one row of grates can be made less or more than that of another selected row or rows thereby providing non-linear movement of the fuel mass at different points on the grate surface.

Any number of grate rows greater than two can be employed in the practice of the invention. The number of pairs of rows required will depend upon the size of the heating system and in some cases upon the type of fuel employed.

It will also be evident that a clinker-grinder can be added to the mechanism by incorporating a linkage or other device associated with any selected one or more of the moving parts of the present invention.

The example of construction just described comprises what the applicant regards as a preferred embodiment of the teachings of the invention. Many modifications of this construction can be made by those skilled in the art without departing from the spirit of these teachings and all such are to be regarded as lying within the ambit of the appended claims.

What I claim is:

l. A reciprocating mechanism for a heat generating system of the type described comprising a supporting frame having rigid side walls, four transversally positioned tracker-bars designed to engage and control a system of grate bars, a spindle remotely but rigidly associated by means of spacing pillars with each tracker-bar below it and in parallel relation thereto and journalled at each end in respective side walls of said frame, a first drive link interconnecting the second and fourth trackerbars in journalled relation therewith, a second drive-link interconnecting the first and third tracker-bars by having its respective ends in journalled relation with extensions normal to the respective axes of the corresponding first and third spindles, the said extensions being respectively rigidly positioned upon said respective spindles degrees from the corresponding said spacing pillars, and a third drive link anti-phasally interconnecting the first and fourth tracker-bars by having its one end journalled upon the said fourth tracker-bar and its other end journalled co-axially' with the pivotal connection of the second drive-link at its point of junction with the said extension positioned normal to the first said spindle, all the drive links being in planes parallel with the said side-walls so that when the first spindle is oscillated about its axis over a predetermined angular range the first and third tracker bars will move arcuately in one direction While the second and fourth tracker-bars will simultaneously move arcuately in the opposite direction. 1

2. The combination set forth in claim 1, and a dump grate residing at the rear of the assembly and characterized by a transversely positioned member upon which the leading edges of adjacent grate members are slidably supported.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 945,469 Mapel Ian. 4, 1910 1,186,971 Davis June 13, 1916 1,564,813 Babendrier Dec. 8, 1925 2,472,746 Gough June 7, 1949 OTHER REFERENCES Number Country Date 538,023 Germany Nov. 9, 1931

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