US3451364A

US3451364A - Reciprocating grate structure

Info

Publication number: US3451364A
Application number: US681845A
Authority: US
Inventors: Lester H Andersen
Original assignee: Clear Air Waste Reduction Inc
Current assignee: Clear Air Waste Reduction Inc
Priority date: 1967-11-09
Filing date: 1967-11-09
Publication date: 1969-06-24
Anticipated expiration: 1986-06-24

Description

v June 24, 1969 L. H. ANDERSEN RECIPROCATING CRATE STRUCTURE Sheet of 5 Original Filed Feb. 14, 1966 June 24, 1969 L H. ANDERSEN 3,451,364 Y RECIPROCATING @RATE STRUCTURE Sheet 2 of 5 Original Filed Feb. 14, 1966 June 24, 1969 L. H. ANDERSEN REC IPHOCATING GRATE STRUCTURE sheet 5 of 5 Original Filed Feb. 14, 1966 swim@ June 24, 1969 L H; ANDERSEN l3,451,364.

RECIPROCAT ING GRATE STRUCTURE original Filed Feb. 14, 196e sheet 4 of 5 @imm @M55/wm @WM Jane 24, 1969 1 H, ANDERSEN 3,451,364

RECIPROCATING GRATE STRUCTURE original Filed Feb. 14, 196e sheet 5 of 5 ijf mm www@ United States Patent O Int. ci. Fasi) 1/22,1/38

U.S. 'CL 110--38 5 'Claims ABSTRACT OF THE DISCLOSURE An eflcient grate structure for incinerating garbage or other refuse characterized by reciprocable frames carrying grate elements provided with small perforations to admit air upwardly therethrough, thus preventing burning refuse from gravitating downwardly through the perforations. The grate is formed in sections which are spaced apart and separated by stationary ratchet-like elements between the sections which permit forward movement of the refuse with the grate means as the grate means advances in a direction away from the intake end of a combustion chamber toward the outlet thereof, and which resist retrograde movement of the refuse when the grate means moves in the opposite direction. A simple rack and pinion means is provided for reciprocating the grates through the medium of opposite limit switches which alternately reverse the direction of rotation of a motor driving the rack and pinion means.

Background and summary of the invention My present invention contemplates in general the provision of grate means as disclosed in my copending application Ser. No. 527,368, iiled Feb. 14, 1966, now abandoned, the present application being a division thereof.

One object of the invention is to provide grate means which is reciprocated in such manner as to advance burning refuse along the grate means and distribute batches thereof over the grate means, stationary ratchetlike advancing elements being provided to assist in the advancing action of the refuse with respect to the grate means; and to provide track and roller means for reciprocably mounting the grate means, rack and pinion means to effect reciprocation of the grate means and track and roller means for mounting the stationary advancing elements on the grate means.

Among specific objects of the invention, one is to provide grate means comprising reciprocable spaced-apart sections and an arrangement of ratchet-like stationary elements between the sections which cooperate with the sections to advance refuse along the grate from the intake end thereof to the discharge end thereof.

Another object is to provide grate means including a refuse receiving wall at the intake end of the grate means, the wall being inclined downwardly from the intake toward the grate means, and an imperforate grate portion being reciprocable thereunder and projecting therefrom, the reciprocations thereof periodically changing the degree of such projection.

Still another object is to provide track and roller means for reciprocably mounting the grate means, rack and pinion means to eect reciprocation of the grate means, and control means responsive to such reciprocations to periodically reverse the pinion means to effect the reciprocations of the rack means and the grate means.

A further object is to provide a plurality of grate means and elongated stationary ratchet-like elements between them to permit forward movement of the refuse with the grate means as the grate means advances in a direction away from the intake and resist retrograde movement of ICC the refuse when the grate means moves in the opposite direction.

Still a further object is to provide track and roller means -for mounting the ratchet-like elements in supported positions on the grate means.

An additional object is to provide an eiicient grate means which includes a first impervious portion adjacent the intake of a combustion chamber, a second impervious portion adjacent the discharge end thereof and a perforated portion between the first and second imperforate portions.

Another additional object is to provide stationary ratchet-like elements of hollow construction and with perforations in their downstream ends to permit discharge therefrom of cooling air received from under the grate means.

A further additional object is to provide means for supplying air under the grate means and into the hollow ratchet-like elements thereof to cool them before discharging through the perforations in their downstream ends.

Still a further additional object is to provide grate means comprising a plurality of frames and a plurality of perforated grate elements resting on each frame and spanning the combustion chamber with the exception of the stationary ratchet-like elements, the adjacent edges of the stationary ratchet-like elements and the grate elements having flange-and-groove sliding coaction with each other.

With these and other objects in view, my invention consists in the construction, arrangement and combination of the various parts of my reciprocating grate structure, whereby the objects above contemplated are attained, as hereinafter more fully set forth, pointed out in my claims and illustrated in detail on the accompanying drawings, wherein:

FIG. 1 is a plan View of my grate means as used in an incinerator disclosed in my parent application.

FIG. 1A is a continuation of FIG. 1 and shows a gas scrubber in horizontal section;

FIG. 2 is a vertical sectional view through the portion of my incinerator shown in FIG. 1, FIG. 1 being taken on the line 1-1 of FIG. 2;

FIG. 2A is a vertical sectional view through the remaining portion of my incinerator and is a continuation of FIG. 2, FIG. 1A being taken on the line 1A-1A of FIG. 2A;

FIG. 3 is a part plan view, part horizontal sectional view taken on the line 3-3 of FIG. 2A;

FIG. 4 is an enlarged horizontal sectional view on the line 4 4 of FIG. 3;

FIG. 5 is a vertical sectional view on the line 5-5 of FIG. 1, and shows the parts on an enlarged scale;

FIG. 6 is a further enlarged detail sectional view of the portion of FIG. 5 shown within the dot-and-dash rectangle 6 thereof;

FIG. 7 is a vertical sectional view on the line 7-7 of FIG. 1 showing details of dry ash conveyor;

FIG. 8 is a vertical sectional view similar to a portion at the right hand end of FIG. 2 to show further details of the dry ash conveyor; and

FIG. 9 is a vertical sectional view on the line 9-9 of FIG. 2 to show details of a rack and pinion drive for grate means of my incinerator,

On the accompanying drawings several areas and dominant parts of my incinerator are designated by reference characters as follows: CJC-Combustion Chamber GM-Grate Means AC--Ash Conveyor GS-Gas Scrubber SC-Sludge Conveyor DA--Deflecting Arch DC--Drying Chamber The combustion chamber CC comprises a floor shown in FIGS. 5, 7 and 8, sidewalls 12 and a top wall 14. The combustion chamber also has a front wall 16 and .a rear wall 18, and adjacent the front wall 16 an inclined wall 20 constituting a garbage chute. As shown in FIG. 2, the left hand end of the combustion chamber is open above the inclined wall 20 so that refuse trucks can back up to the combustion chamber and discharge their contents down the inclined wall 20 on to the grate means GM. Such open end is designated 13.

The walls 12 and 14 have

extensions

12a and 14a at the right hand end in FIGS. 1 and 2 which continue into FIGS. 1A and 2A to form a baflie chamber wherein a baie 18a shown in FIGS. 1 and 2 is an upward extension of the rear wall 18 of the combustion chamber, and a downwardly extending baffle 22 shown in FIGS. 1A and 2A is provided, both upstream from the gas scrubber GS. The baffle chamber is provided with a sloping floor 24 which continues as at 24a in FIGS. lA and 2A to form a floor for the gas scrubber GS.

The floor 24a, sidewalls 26 and a top wall 14b which is an extension of the top wall 14' provide a gas scrubber chamber, the details of which are shown in FIGS. 1A and 2A. In this chamber a series of vertical piers 28 constitute scrubber elements which, as shown in FIG. 1A, are arranged in rows ,and staggered relative to each other in successive rows to provide a tortuous path for the products of combustion and iiy ash passing through the gas scrubber GS. These piers are spaced so that the area between them for the flow of combustion gases is reduced to about one-third the area within the

bathe chamber

12a, 14a, 24, so that the velocity of combustion gases and fly ash through the gas scrubber is increased for ericiency of the gas scrubbing operation as will hereinafter appear.

The gas scrubber GS also includes a water distributing manifold 30 adapted to be kept lled with water and having a slot 32 so that a curtain 34 of water falls therefrom as illustrated in FIGS. 1A and 2A when there is no flow of combustion gases through the gas scrubber. This curtain is broken up for an important reason which will hereinafter appear during operation of my incinerator.

The products of combustion after leaving the gas scrubber GS enter a plenum chamber 36 shown in FIG. 2A and ow upwardly through the drying chamber DC, first passing through the deflecting arch DA. The dellecting a-rch comprises a horizontal wall 38 of concrete or the like having reinforcing elements 40 therein and having a series of inclined passages 42 which, as shown in FIG. 2A will deflect the gases of combustion toward the sides of the drying chamber DC which chamber may have a vertical height approximately the same as shown for the plenum chamber 36 Q portions having been broken away to conserve space on the drawing). At the top of the drying chamber DC, a blower 44 is provided suitably driven as by an electric motor 46. The blower has an intake chamber 48 and a discharge chamber 50 to atmosphere.

The grate means GM comprises perforated grates 52 and a means to support them so that they are reciprocably mounted. These grates may be formed of cast iron or the like with small holes drilled therethrough .as shown in FIG. l, and as shown in FIGS. 2, 5, 6 and 9 the grates rest on grate carriers 54 which are supported by a framework of lateral and longitudinal I-

beam

56 and 58, respectively. The I-bearns 58 are supported by rollers 60` which in turn are journalled in stationary brackets on a partition 62 as shown in FIGS. 5 and 9 and a pair of shoulders 64 of the combustion chamber sidewalls 12.

The

framework

56, 58, also carries five rows of rollers 68 to support longitudinal channels 66 which are secured at 70 to the front wall 16 as shown in FIG. 2 so that the framework can reciprocate beneath the channels but at the same time will support them. Surrnounting the channels 66 are inverted channels 72 having side edges which are grooved ash shown in FIG. 5 to coact with end flanges 74 of the grates 52 to effect a satisfactory seal for combustion purposes between the channels 72 and the grates. The inverted channels 72 have ratchet-like projections 76 having an important function for the burning refuse as will be described later. Reciprocations are imparted to the grate means GM by -reciprocating the

frame

56, 58, which has attached thereto three racks 78 as shown in FIGS. 2 and 9 meshing with pinions 80 on a shaft 82. A chain 84 operatively connects the shaft 82 to the output of a speed reducer 86 driven by a motor 88. The motor is under control of a projection 83 (shown in FIG. 1) which coacts with .a pair of limit switches 85 and 87 to energize the motor for rotation in alternately opposite directions in a manner well known in the art, thus automatically reciprocating the grate means GM as long as current is supplied to the motor and controlled by the limit switches.

For supplying combustion air to the combustion chamber CC above the grate GM, blowers 90 are provided as shown in FIGS. l and 5 driven by motors 91 and supplying air to manifolds 92 extending along the sidewalls 12. A plurality of nozzles 94 extend from each manifold 92 into Venturi tubes 96 arranged at angles such .as shown in order to furnish air for combustion in a direction downwardly from the sidewalls .12 and toward the center of the grate means GM.

Additional combustion air is supplied by a blower 98 driven by a motor 100 and discharging into a duct 102 having

discharge openings

104 and 106 on opposite sides of the partition 62 as shown in FIG. 5 for supplying combustion air beneath the grate means GM. The grate means is inclined to facilitate the movement of burning refuse therealong toward the dry .ash conveyor AC and to eifect a more even spreading and leveling out of the refuse and to effect distribution of combustion air through the grate 52 to the refuse. The downhill ends of the projections 76 are perforated as shown at 77 in FIGS. 5 and 6 to keep them relatively cool and promote more complete combustion of the refuse.

As will hereinafter appear, water containing y ash flows downwardly along the inclined bottom wall 24a of the gas scrubber as shown in FIG. 2A into a trough 108. Discharge openings lead therefrom into a sludge conveyor trough 112 containing the sluge conveyor SC. The trough 112 as shown in FIG. 3 and dotted in FIG. 2A leads to a sump 114 from which the water is pumped by .a pump 1.16 driven by a motor 118, the intake of the pump being shown at 120. The trough 112 and the sump 114 thus constitute an open L-shaped settling tank from which Water is drawn for recirculation to the gas scrubber. The pump and motor are contained in a compartment 122 sealed off from the tank 112, 114, and the pump has .an outlet pipe 124 leading to the manifold 30. A barile 126 serves as an aid to prevent the ow of sludge from the bottom of the trough 112 and the sump 114 into the intake 120.

In order to keep the water in the trough 112 and the sump 114 at a predetermined level 113 such as shown in FIG. 2A, a water supply line 128 ilows through a water meter 130 to a float valve 132 in a float chamber 134. The float chamber .134 has an outlet 136 leading into the sump 114. This arrangement provides make-up water to compensate for that which is evaporated by operation of the incinerator. In .actual practice I find that a high water recovery is possible thus requiring only a nominal amount of make-up water and effecting a substantial economy in the use of water.

The ash conveyor AC as shown in FIG. 2 is adapted to receive dry ashes falling off the lower (right hand) end of the grate means GM which it will be noted is inclined downwardly toward the ash conveyor. The marginal right hand end of the grate means reciprocates as indicated by dot-and-dash lines over the ash conveyor so Ias to discharge ashes directly into the conveyor. As noted in FIG. 1, the major area f the grate means GM is provided with the perforated grates 52 whereas the left hand end under the inclined wall 20 and the right hand marginal end are provided with imperforate members 138 so that the burning of refuse is accomplished between the discharge end of the inclined wall 20 and the imperforate members 138 at the downhill end of the grate means. The imperforate members 138 just mentioned serve as a platform for the advance of ashes from the grates 52 and into the ash conveyor AC. As shown in FIG. 7, the ash conveyor at the right hand end has an upwardly and outwardly inclined portion 139 extending from the combustion chamber to discharge in an ash box 140 or the like and is driven by a chain 142 from the output shaft of a speed rreducer 144 driven by a motor 146.

The sludge conveyor SC is somewhat similar in vertical cross section to the ash conveyor AC shown in FIG. 7, being driven by a chain 148 (FIG. 3) from a speed reducer 150 which in turn is driven by an electric motor 152. The sludge conveyor discharges into a sludge box 154 or the sludge may be otherwise disposed of.

Practical operationI In the operation of my refuse incinerator, atruck load of refuse is dumped into the open end 13 of the combustion chamber CC and slides down the inclined wall 20 on to the imperforate members 138. Since a considerable portion of normal household and industrial waste and similar refuse consists of paper and other combustible materials, it can be readily ignited, and after suitable ignition, the

blowers

44, 90 and 98 may have their motors energized for operation. The motor 88 may also be energized for reciprocating the gate means GM and the

motors

146 and 152 may be energized for operating the ash conveyor AC and the sludge conveyor SC. The grate means GM is so designed as to hold and disturb the refuse for efficient aeration which results in faster and more complete burning when compared to burning on stationary grates.

The burning refuse produces products of combustion including ffy ash and dry ashes. The dry ashes are gradually deposited in the ash conveyor AC due to the reciprocations of the grate means GM. The dry ashes are carried by the ash conveyor AC up the inclined portion 139 of the conveyor and into the ash box 140 or are otherwise disposed of.

Refuse is advanced along the grate means GM by reason of positional changes of the refuse relative to the grate accomplished during the backward portion of reciprocating grate motion. During the forward portion of grate motion a clear area of grate 138 becomes exposed from under the inclined wall 20 and is thereupon covered with incoming refuse. Accordingly, as grate motion reverses the refuse now becomes positionally held by the inclined wall 20 while the grate slips beneath the refuse thereby effecting a change of position relative tothe grate. The retarding effect of the inclined wall 20 is impa-rted through the refuse to all the burning material on the grate means, but not proportionally so. Heavier parts of the conglomerate refuse s-lip the grate less due to greater friction, and lighter parts thereby flow around and past the heavier parts. Advancement of refuse along the grate is maintained as long as incoming refuse is sufficiently present on the inclined wall 20 to cover the free area exposed during forward grate motion.

Large variations in the rate of burning are inherent in the particle disorder of accumulated refuse with it varied physical geometry and material chemistry. `It is to this situation that my grate is particularly adaptable. As refuse moves onto the grate, ignition of the refuse occurs on the inclined wall 20 due to kindling from slower moving parts of preceding quantities. The selectivity of movement to various particle weights becomes increasingly defined while movement progresses. As advancement of the burning particles continues, rates of burning are equated by combustion to changes in density to which the grate means is selective and thereby translates to rates of movement. The accuracy of translation is evidenced by a line of demarcation that defines the inert .material toward the discharge end of the grate. In essence, rates of burning become rates of movement, and in such manner variables in the incineration of refuse are accommodated by the grate means as herein disclosed.

The foregoing described operation has the effect of breaking down the individual batches of refuse land substantially evenly distributing them over the grate means. Additional batches of refuse can be periodically fed to the incinerator to keep it in continuous operation. The major function of the projections 76 is to lift and disturb portions of the load `during forward grate motion for more effective aeration and consequent burning.

The products of combustion including fly ash pass upwardly and over the baffle 18@l as indicated by arrows in FIG. 2 and under the baffle 22 of FIG. 2A to the gas scrubber GS. The temperature generated in the combustion chamber may run as high as 1600 F. to l800 F. and the velocity of the products of combustion and ily ash from the outlet end of the combustion chamber may be in the range of 1000 fpm. to 3000 f.p.m. caused by the operation of the blowers 44, and 98. Such high velocity is desirable in order to effectively wet the surfaces of the piers 28 with water from the curtain of water 34 which, of course, is distorted from the showing in FIG. 2A when the blowers are in operation. I have found that the water effectively wets the surfaces of the piers 28 so most of the fly ash will be collected in the water that gravitates downwardly along the piers and flows downhill along the gas scrubber chamber floor 241n and into the trough 108. The water also has the effect of keeping the piers 28 cool relative to the transit gases of combustion by thermal sink losses and vaporization of the water.

Due to the increase in velocity of the products of combustion through the gas scrubber, as well as the presence of water therein as films on the piers 28 and the cooling effect of the water as it evaporates, the temperature is only about 200 to 250 F. around the piers. The velocity is then reduced again in the drying chamber DC so that the temperature is increased to something like 400 F. thus increasing the drying effect and making for a gas scrubber and gas dryer combination having a high overall efficiency.

By staggering the piers as shown in FIG. 1A, the flow past the first row impinges the second row and the flow past the second row impinges the third row and so on, in such manner as to effectively accomplish maximum collection of y ash. These piers are formed preferably of water-repellent ceramic capable of withstanding high temperature on the order encountered in the gas scrubber and to withstand the abrasive effect of the fiy ash impinging against them. Also, the spacing between the piers is such as to reduce the area through which the products of combustion pass as they flow through the gas scrubber so that an even higher velocity is attained in the gas scrubber (on the order of 3000 to 9000 f.p.m.).

As for the arrangement of the piers 28 in rows in the gas scrubber GS, the first row of piers has the effect of reducing the temperature of the products of combustion and the second row, because the piers thereof are offset relative to the piers of the first row, causes fly ash to impinge on their water films so as to be entrained in the water that gravitates downwardly along the piers. Likewise the third row being offset from the second row performs the same function as the second row and so does the fourth row. The piers obviously act as retarders for the products of combustion to effect separation of fly ash therefrom. The third and fourth rows :serve as a final wash for the removal of most of the residual fly ash from the first and second row, and by the time the products of combustion pass the fourth row, up to of the fly ash has been removed. Ceramic piers are provided in place of metal baffles as in existing gas scrubbers as they are more resistant to the abrasive elfect of the ily ash and insure Contact of the ily ash with the Water for eliicient removal of the ily ash. Longer life for the piers is thus experienced in an installation of the kind herein disclosed. Slugs of water from the curtain 34 act as lubricant for the lly ash thus reducing wea-r on the piers.

The relatively clean products of combustion and some water entrained therewith are discharged from the gas scrubber GS into the plenum chamber 36 wherein they flow upwardly through the dellection arch DA and into the drying chamber DC. The passageways 42 of the dellction arch, being inclined as they are, direct the products 'and water toward the walls of the drying chamber as illustrated by arrows in FIG. 2A and the impingement of the water against these walls results in a drying reaction by reason of such water trickling down the walls of the plenum chamber and eventually into the trough 108. Accordingly, products of combustion almost entirely free of fly ash are discharged into the inlet 48 and through the blower 44 and its outlet 50 to atmosphere, thus producing a clean burning refuse incinerator satisfactory for the requirements o-f most smoke ordinances.

The fly ash and water draining from the gas scrubber into the trough 108 drains through the discharge openings 110 into the sludge conveyor trough 112 and the sludge settles to the bottom of the trough whereby it may be picked up by the lower stretch `of blades of the sludge conveyor SC and pushed along the trough 112 toward the right and then up the inclined portion 139 and into the sludge box 154. Excess water drains back into the trough 112 and linds its way into the sump 114 where the Water can be recirculated to the manifold 30 and the slot 32 to effect an economy of operation represented by a considenab'le saving of water as distinguished from those types of gas scrubbers which nse fresh water throughout their operation without recirculation. Some of the water, however, will evaporate because of the heat generated in the incinerator and this is automatically compensated for by operation of the -l'loat valve 1132 which may be set to replenish the water to the level 113` shown in FIG. 2A.

From the foregoing specilcation, it will be obvious that I have provided a refuse incinerator and a method of treating refuse which accomplish the objects set forth in the foregoing specification. An incinerator is disclosed which does not need a high chimney to create draft as in many installations where the chimney alone may cost as much as $125,000.00. In many prior art refuse incinerators the cost of blowers is also high because they must withstand considerable abrasive action by fly ash whereas in my installation the blower 44 can be of a relatively inexpensive type since the products of combustion passing therethrough are relatively free of fly ash.

My apparatus and method contribute to minimization of air pollution as the output from my incinerator is about 90% to 95% cleaner than the output from conventional chimneys, caused, of course, by the removal of a greater proportion of liy ash in the eicient gas scrubber disclosed. As far as complete refuse ncinerator systems of comparable size are concerned, those with stacks or chimneys may cost three times as much as an installation of the kind herein disclosed.

Some changes may be made in the construction and arrangement of the parts of my incinerator, and my method steps may be varied to some extent without departing from the real spirit and purpose of my invention.

I claim as my invention:

1. A reciprocating grate struct-ure comprising grate means mounted to reciprocate longitudinally of a combustion chamber having an inlet end and an outlet end, said grate means being inclined downwardly from said inlet end toward said outlet end whereby the reciprocations thereof tend to advance the burning material along said grate means, said grate means comprising grate elements provided with small perforations to admit air upwardly therethrough thus preventing burning material on the grate means yfrom gravitating downwardly through said perforations, and means at the lower end of said grate means to receive residual dry ashes and other residue lof the burning material which are not carried away with other products of combustion along with draft air through the combustion chamber, said grate means being formed of a plurality of laterally spaced sections, and elongated stationary ratchet-like elements provided between said sections to permit forward movement of the burning material with the grate means as the grate means advances in a direction away from said intake, and to resist retrograde movement of the burning material when the grate means moves in the opposite direction.

2. A reciprocating grate structure according to claim 1 wherein said grate means includes track and roller means for reciprocably mounting the grate means, rack and pinion means to effect reciprocations of the grate means, and track and roller means for mounting said ratchet-like elements in supported position on said grate means.

3. A reciprocating grate structure according to claim 1 wherein said stationary ratchet-like elements are hollow and have perforations in their downstream ends to permit discharge therefrom of cooling air received from under said grate means.

4. A reciprocating grate structure according to claim 3 wherein a blower constitutes means for supplying air under said grate means and into said hollow ratchet-like elements to cool them before such air discharges through said perforations of said ratchet-like elements to support combustion of burning material on said grate means.

5. An incinerator in accordance with claim 1 wherein said grate means comprises a plurality of frames, and a plurality of perforated grate elements resting on each frame and spanning said combustion chamber with the exception of said stationary ratchet-like elements, the adjacent edges of said stationary ratchet-like elements and said grate elements having ange-and-groove sliding coaction with each other.

References Cited UNITED STATES PATENTS 1,180,737 4/1916 Rees 110-38 1,211,755 1/1917 Reagan 110-38 1,245,914 l1/1917` Helseth 110-15 1,517,319 12/1924 Seyboth 110-7 1,811,339 y6/1931 Van Der Does De Bige 110-38 2,008,884 7/1935 Tuppen 110-15 2,978,997 4/ 1961 Pierce 110-18 JAMES W. WESTHAVER, Primary Examiner.

U.S. C1. X.R. L--7 fzgjgo UNITED STATES PATENT OFFICE CERTIFICATE OF CRRECTION Paten: No. 3,451,364 Dated June 24, 1969 Inventor(s) l L. H. Andersen It is certified thaterror appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 53, "FIG. 1" should be FIG. 2.

Column 6, line 53, "Water-repellent" should be --water resistant".

Column 8, line 44, "An incnerator" should be --A reciprocating grate Slr ANU c um Mamma. n. Ofr Gomisslm or hun