US1314009A - Allan b - Google Patents

Description

A. M. MASSER.

GRATE BAR.

APPLICATION men MAY 2|. m2.

Patented Aug. 26, 1919.

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UNITED STATES PATENT OFFICE.

ALLAN M. MASSER, OF CHICAGO, ILLINOIS, ASSIGNOR 'IO COMBUSTION SERVICE CORPORATION, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

GRATIS-BAR.

Specification of Letters Patent.

Patented A11 26, 1919.

To all whom it may concern:

Be it known that I, ALLAN M. MAssnn, a citizen of the United States of America, and a resident of Chicago, county of Cook, and State of Illinois, have invented certain new and useful Improvements in Grate-Bars, of which the following is a specification.

This invention relates to grate bars, and particularly to those which are intended for use in coal furnaces having forced draft. Some of the prime requisites of such bars are permanence of form, capability to distribute the supply of air for combustion as uniformly as possible throughout the grate area and to preheat the air nearly to the ignition temperature in transmitting it to the fuel, and also capability to rapidly conduct away excessive heat from the combustio-n surfaces and distribute such heat to the more remote and downward parts of the grate whereby it may most efliciently preheat the air and whereby any excess heat may be radiated and suitably disposed of without harm.

Many attempts have heretofore been made to meet these requirements efficiently, and varying degrees of success have been attained by fitting the bars together in various ways and providing apertures and air passages in, through and between the bars, but the prior devices for one reason or another have been more or less deficient, and moreover the ever increasing demands for capacity, space economy, smoke prevention, low initial cost, and inexpensive maintenance and operation continually develop new problems of refinement and efficiency.

WVhen coal is burned the process which occurs consists of two distinct ope -ations, which, however, may be continuous and the one immediately successive with respect to the other. The first operation, which requires a comparatively low temperature and is independent of the presence of air, is one of destructive distillation similar to that which occurs in the retorts of gasworks. It

results in the decomposition of the coal and formation of numerous substances including hydrogen and certain hydrocarbon gases, certain nitrogenous compounds, and coke. It is these products of distillation, not the coal itself, that burn, in the strict sense of the word; and this second operation requires the presence of air and also a much higher temperature than the first. If the combustion is perfect the products are mainly water-vapor, carbon dioxid, nitrogen, and sulfur dioxid, part of the nitrogen being liberated from the fuel but the greater part being derived from the air which has supplied the necessary oxygen.

Two things are necessary for insuring such complete combustion, namely an adequate but not too large supply of air properly administered, and the maintenance of the requisite temperature. In practice, however, these conditions are never perfectly fulfilled and consequently the combustion of coal is always more or less imperfect and gives rise to a greater or less waste of fuel elements, the more important of which include certain hydrocarbons, carbon monoxid, and unburnt carbon in a very finely divided state. This mixture commonly referred to as smoke usually includes considerable volumes of unused air.

The main objects of this invention are to provide an improved and more eflicient form of g ate, adapted especially for forced draft furnaces; to provide an improved form of grate bar adapted to avoid warping, and having apertures better disposed and shaped to economically distribute and discharge the certain requisite supply of air at a proper temperature forcibly and uni-- formly in finely divided streams, well distributed, so as to effect more even and speedy combustion, and so as to avoid admission and useless heating of more air than required tov support complete combustion; to so form and dispose the apertures as to avoid substantial weakening of the bars, and so as to cause upward cross currents of air to be discharged obliquely into the fuel in such manner as to more thoroughly equalize the distribution of air throughout the fuel mass and thus permit of supplying a thicker fuel bed such as may require the least amount of attention and may keep free from holes burning through; and to provide downward ribs or flanges on the bars, formed and adapted both to preheat the air and by due 'adiation to prevent warping or fusing of the bars, as well as to reinforce the bars and provide suitable pockets for the collection of a packing of cindors and ash between bars so as to insure all of the air passing through the bar apertures or perforations.

An illustrative embodiment of this invention is shown in the accompanying drawings, in which Figure 1 is a fragmentary plan showing adjacent ends of a plurality of the improved grate bars, relatively disposed as in a grate.

Fig. 2 is a central vertical section running lengthwise through one of the bars on the line .AA of Figs. 1 and 2.

Fig. 3 is a cross section through a' group of bars on the line BB of Fig. 1.

In the embodiment shown in the drawings each bar 1 comprises a horizontal body part 2 having downward flanges 3 on each side and also a medial downward web 1. These flanges and webs constituting substantially a series of ribs, giving the bar an M-shape, and serve mainly for two important functions, namely to strengthen the bar, which is made as light as practicable, and to facilitate distribution and radiation of heat, as well as preheating of the draft air. The strengthening is effected by the truss-like form of the downward members 3 and 4E, and heat radiation and preheating are efliciently provided for by the broad surfaces which said flange and web members expose to the air passing through the narrow spaces between them.

In order to distribute the air of the forced draft uniformly and efliciently over the whole grate area and to best adapt the grate for insuring proper combustion, numerous small apertures or air passages through the bars are provided of definite form and particular relation with respect to each other and to the several parts of the bar, as will be more fully described. For this purpose each bar is provided with alternate groups of perforations 5 and 6 respectively, said groups as such being of different character and form, the holes 5 being arranged in circular form and the holes 6 being arranged in pairs alined crosswise of the bars. In each group the holes are disposed symmetrically on opposite sides of the middle rib or web 4. The holes or jets 5 and 6 are all inclined divergently upward in each group so as to impart somewhat of radial movement to the air as it is discharged upward into the fuel, and the discharge or nozzle end of each hole is considerably restricted or narrowed with respect to the intake end and body of the passage, so as to cause the air to be ejected forcibly well up into the mass of the fuel.

Each circular group of holes 5 preferably comprises a pair of nearly semicircular apertures, one on each side of web 4, and the outward flare of each preferably increases somewhat toward the top, as best shown by the outer bar sections in Fig. 3. The restricted nozzle effect is also well shown in this view. It is also found that alternate adjacent bar ends may to advantage be provided with a pair of quadrant apertures 5, as shown in the second bar of Fig. 1, so as to utilize the space outside of what would otherwise be the end apertures 6 of alternate bars.

Each pair of narrow apertures 6 comprises two substantially straight holes or jets also restricted at their upper ends. The nozzle-like shape and the upward divergence of these apertures is well shown in the middle bar of Fig. l I

In order that the circle group holes 5 and the line-group holes 6 may come in alternate alinement when the bars are assembled, the group spacing is made alike on all of the bars and alternate'bars :begin with holes 5 and 5' respectively as shown in Fig. 1. This result may be had by making the bars a'll alike, and each terminating at one end with a quadrant group of holes 5, and at the opposite end with a circlegroup of holes 5, and then assembling the bars in alternate relative position, as will readily be understood by reference to Fig. 1.

The bars are thickened vertically some what at their ends or hearing points 1, and as a result the casting is more massive here. The ribs 3 and 4: terminate somewhat short of the bar ends, so as to leave a flat even bearing surface on the under side, as shown in Fig. 2.

In order that the grate as a whole may readily be made substantially air tight, except for the holes 5 and 6, and in order to made due allowance for expansion and 'shrinkage'at times, provision is made for deep ash pockets 7 between bars. For this purpose a slight rim or flange 8 is cast or otherwise provided on the outer side of the outer ribs 4 adjacent to their lower edges and extending the whole length of the bars, the abutting flanges 8 on .adjacent bars constituting complementary bottomparts of the pockets 7 Each pocket flange 8 follows the 3, which like rib 4 is deepest at the center and turns upward sharply near the ends as shown at 8 'on Fig. 2, from whence it extends horizontally to the tip of the bar. lVhen the bars are assembled in the grate they are preferably spaced slightly at the edges of the pocket flanges 8, so as to accommodate expansion, but not enough to permit ashes to leak through appreciably. In use the pockets? soon become packed full of ashes and cinders and are practically air tight so that the draft is limited to the spe-' cial draft apertures 5 and 6. When the iVl-bars are thus assembled in the grate the adjacent flanges 3 of adjoining bars constituge complementary parts of composite grate n s.

The draft air is heated mainly as it passes aipward at comparatively low speed through v 110 downwardly convex curved edge of the rib the long narrow channels or grooves 9 between the ribs 3 and 4, and receives its final high degree temperature as it rushes out through the narrow jets 5 and 6. From these jets the hot air blast is driven obliquely upward well into the mass of burning fuel so that combustion is hastened and a more intimate mixture of air with the combustible gases passing to the combustion chamber occurs.

Although but one specific embodiment of this invention has been herein shown and described, it will be understood that numerous details of the construction shown may be altered or omitted without departing from the spirit of this invention as defined by the following claims.

I claim:

1. In a grate adapted for preheating the air and efiiciently distributing same in connection with forced draft, a plurality of apertured grate bars disposed closely together in draft-tight relation, the apertures in each bar being in the form of perforations disposed in definite group arrangements, each bar having uniformly spaced alternating group forms, the adjacent bars having different group forms disposed adjacently.

2. In a grate adapted for forced draft, a plurality of apertured grate bars disposed closely together in draft-tight relation, the apertures in each bar being in the form of peculiarly shaped perforations disposed in group forms disposed adjacently,

definite group arrangements, each bar having uniformly spaced alternating group forms, the adjacent bars having different the holes in said groups being disposed symmetrically about their respective group axes and inclined divergently toward the top.

3. In a grate, a plurality of g'ate bars each having a downwardly ribbed flat body part containing alternate groups of perforations, one series of said groups being ar ranged in pairs and the groups of the other series being arranged each in circular form, the circular groups in one bar being opposite the pair groups in the adjacent bars, and vice versa.

4:. A grate having draft apertures in distinct groups of circular and right-line form respectively, said groups being disposed alternately in each of two directions at right angles to each other, said grate comprising a series of downwardly ribbed bars in which the said apertures are formed, said bars having medial ribs and deep lateral flanges which abut at their lower edges against corresponding flanges on adjacent bars and constitute complementary parts of composite grate ribs, and the apertures of each group bein disposed symmetrically with respect to said medial ribs.

Signed at Chicago this 28th day of April 1917.

ALLAN M. MASSER.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, I). G.

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