US1649147A - Machine for the production of powdered fuel - Google Patents

Description

NW, m K270 LMQAW C. E. BLYTH MACHINE FOR THE PRODUCTION OF POWDERED FUEL Filed Sept. 8 1925 2 Sheets-Sheet l NV ENTOR Charles E. Blyzh ATTORN Y C. E. BLYTH MACHINE FOR THE PRODUCTION OF POWDERED FUEL Filed Sept. 8. 1925 2 Sheets-Sheet 2 all -"9 K any. 7

WITNESS E5 4 INVENTOR $6 If CharlesEZBlyth W K HTTw Patented Nov. 15,, 192W.

untrue STATES,

CHARLES E. BLYTH, OF DUNCHURCE, ENGLAND, ASSIGNOR TO AI-JFBED HERBERT LTD,

' OF COVENTRY, ENGLAND.

MACHINE FOR THE PRODUCTION FQWDER'JED FUEL.

This invention relates to pulverizing'machines and more particularly to machines of the type shown in the-patent to Blyth, No. 1,446,151, dated February 20, 1923. It

has. been found as the result of experimental studies on the machine shown in the Blyth patent for pulverizing fuel, that if the impact pegs on the casing and the rotor in the second grinding zone are of full length and project substantially the whole distance from the rotor to the casing wall, these pegs set up a centrifugal action in opposition to theexhaust fan which makes it impossible to get enough pulverized fuel through the 5 machine to form a flame. The length of the pegs on the rotor is therefore an important factor in the operation of the machine. It is also found that if the coarse pieces of material should escape from the second pulverizing zone into the fan casing without being broken to a sufliciently fine size, they impose a burden on the fan of subdividing them sufficiently to permit their passing with the fine fuel into the burner, as the heavy particles cannot be blown along with the air unless they are reduced to a very small size. It is therefore necessary, if fine grinding is to be done, that the coarse particles be rejected at the entrance to the fan chamber. In the construction illustrated in in my prior patent, twp sets ofclosely ar ranged fan belts are mounted to revolve with the rotor,one in the inlet zone near the periphery o'f'the disk and the other located f in the second zone near the outlet pipe. The

blades in the second zone reject coarse particles attempting to pass therethrough but they are not properly located and arranged to scoop the coarse material from the outgoing air current and hurl it back into the path of the revolving pegs satisfactorily and eficiently. The outflow of the air is impeded by these blades and the restricted outlet passage, andthe counter air pressure thus set up requires greater efiort on the art of the main fan to remove the material rom the pulverizing chamber. Since these blades are subjected to severe wear and will have but short lives, it is necessary to shut down the machine frequently for repairs, and the parts are expensive and dificult to replace. For such reasons, scribed in my-prior patent is not commercially practical.

it is accordingly the main object of my the machine deinvention to overcome these difficulties and 7 improve the machine shown in said patent, and particularly to provide a machine adapted for pulverizing fuel, which will be highly-efficient in operation and will have a large capacity and a long life of useful service.

It is a further object of myinvention to provide a construction which will serve efficientlyto scoop thecoarse particles from the air current assing to the outlet and to permitonly suc finely pulverized material as will travel in a cloudlike formation to pass through therejector from the pulverizing zone to the fancasing and to throw the coarse particles back into the path of the pegs for further pulverization.

It isa still further object to provide an arrangement of attrition pegs in the second zone which will permitthe passage of air, and the finally divided fuel carried thereby, from the first grinding zone to the fan chamber, and yet will serve to grind efficiently the material supplied thereto and particularly to provide-such an arrangement that the fuel may be rejected-at the outlet and forced to recirculate repeatedly in this second zone until it has been ground to such a fine size that it will pass readily between the rejector arms. 7 I

With these and other objects in view as will be apparent in the following disclosure, my invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.

Referring to the drawin in which like reference numerals indicate li ke parts:

Fig. 1 is a vertical section partly broken away of that portion of the pulverizer which relates to the resent invention;

Fig. 2 is a fragmentary perspective view of a portion of the device;

Fig. 3 is a fragmentary vertical elevation of a glart of the rotor showing the passage theret rough for rejected material; 7

Fig. 4 is a cross section of the part shown in Fig. 3;

Figs. 5 and 6 are front and side elevational views of one of the rejector arms; and

Fig. 7 is a diagrammatic view illustrating the supposed path of travel of the pulverine material.

As will be understood by reference to the prior patent to Blyth, this type of machine comprises a hollow, cylindrical casing in,

close to the exit orifice 29 of the within which is rotatably mounted a disk 11 supported on and rotated by a shaft 12 driven by any suitable source of power. The manner of mounting the disk on the shaft may be in accordance with any well known mechanical construction, and I have herein illustrated the rotor as mounted on a sleeve 13 and clamped in position therein by means of an adjustable collar 14. The rotor 11 comprises two plates 15 and 16, as shown particularly in Fig. 4, and a set of attrition pegs 18 and 19 are mounted on opposite sides of these plates in any suitable manner. In the-present instance, the pegs are provided with enlarged heads which are clamped between the plates 15 and 16. Similarly two sets of pegs 20 and 21 are mounted on the opposite side walls of the casing 10. the pegs 20 interfitting with the pegs 18 and pegs 21 on the opposite wall of the casing interfitting with the pegs 19, these various sets of pegs being so located that the pegs on the rotor may pass between the pegs on the casing wall and pulverize material by impact therebetween. 7

Material is fed into the machine through a hopper 25 and into the passage 26 and thence centrally into the chamber on the left hand side of the rotor shown in Fig. 1. The material is brokenby impact between the pegs 18 and 20 and due to the suction of the fan 28 which is adjacent the exit 29 of the casing, the material tends to travel from this chamber around the annual portion of the rotor into the second chamber formed between the rotor and the right hand wall of the casing. Air is admitted into the pulverizing chamber through the pasages 31 and 32.

I find it desirable to provide a device which will reject any over-sized material which would otherwise escape through the exit 29 and insure its retention in the pulverizing chamber until it is ground to the desired degree of fineness. One simple construction for accomplishing this purpose com rises a set of rejector arms 35 mounted on t e sleeve 13 to rotate with the shaft 12 and located outside of the grinding zone close to the exit 29. These arms are preferably disposed substantially radially to the shaft and are so shaped that they automatically scoop all coarse material from the air current; and throw it back into the grinding zone.

While these rejector arms may be madein various shapes and arrangements, I have shown them herein as having forwardly facing concave surfaces formed of hollow pieces of pipe which are cut away and bent as shown particularly in Figs. 2, 5 and 6, to form -U-shaped troughs 36 which serve to scoop the material from the air current and hurl it centrifugally out of the open end of the trough. These rejector arms are located ulverizer casing so that they will not be in t e field of screwed into corresponding pockets in a split collar 37 and held in place by lock nuts 39. The arms extend all the way across the exit opening 29 and close to a ring 40 which is fastened to the wall 41 of the casing.

The arms are arranged with the hollow U- shaped portions 36 facing in the directionof revolution of .the arms- The arms are bent backwards slightly, as indicated by the curve 42 in Fig. 6, and the ring 40 is beveled off as shown particularly in Fig. 2 so that material striking this ring will be given a glancing blow and thrown back into the grinding zone. These rapidly rotating arms therefore form ascreen through which the slowly moving solid particles cannot pass, but which lets a cloud of fine material pass between the arms into the fan chamber. The coarse material is thrown outwardly against the rotor or in the path of the pegs in the grinding zone and are thus returned by centrifugal action toward the outer portion of the casing where they are efi'ectively ground before they can get back towards the exit.

In certain instances, I may utilize a feature illustrated in the drawings, which, however, may be omitted if desired. This comprises a series of perforations 50 and 51 in the two plates 15 and 16'of the rotor, which are so located that material thrown by a glancing blow against the ring 40 is deflected along the line c0 in Fig. 7 and much of it will pass outwardly through the openings 50 and 51 of the rotor into the chamber of the first effect where the coarser material is initially ground. In order to assist in this action and at the same time help to pre vent material in the first chamber from passing through these openings into the second chamber without being ground, I preferably form the walls of the openings 50 and 51 of a flaring shape as illustrated particularly in Figs. 3 and 4. The flared portions 53 of these openings serve as vanes which tend to deflect material striking against the surfaces and thrust it back into the same grinding zone. It is also possible that these passa es through the rotor serve to equalize t e air pressure within the casing and admit directly into the chamber of the second effect a clou 0f fine material which has been sulficiently ulverized in the chamber of the first effect, tlius short-circuiting some of the air through the rotor and counteracting the centrifugal force which tends to pass all of the material around the outer edge of the rotor.

In the first grinding zone, the tendency of the rotating pegs is to move the material outwardly toward the periphery of the disk and thus aid the fan in drawing the material through the casing, whereas in the second zone the rotating pegs tend to counteract the hurltthe same into the path of the impact members.

3. A fuel pulverizing machine comprising a casing having a fuel and air entrance, a rotor. mounted therein, impact pegs on said casing and rotor arranged to pulverize'the fuel by impact thereagainst, a deflecting ring on the casing defining an exit for the pulverized fuel mixed with said air, and spaced radial rejector arms mounted to revolve close to said ring which have forwardly facing surfaces shaped and arranged to throw the coarse material against said ring and into the pulverizing chamber but permlt the passage of a cloud of air and finely divided material between said arms.

4. A pulverizing machine comprising a casing having an entrance and an exit for air and the fuel on opposite sides thereof, a bait rotatably mounted in the casing, a rotor fixed to said shaft, cooperating impact members on both sides of said casing .and rotor arranged to form two communicating pulverizing zones, and a series of rejector arms mounted on said shaft close to the exit in the second zone and arranged to revolve with the rotor and prevent the passage of coarse fuel through the exit, said rotor having openings therethrough so located and shaped that coarse material thrown by said rejector arms may be returned to the first grinding zone.

5. A pulverizing machine comprising a casing having an inlet and a centrally located outlet for air and the material to be pulverized, means in the casing to pulverize said material and revoluble radial rejector arms adjacent the outlet which have forwardly facing concave surfaces arranged to scoop coarse particles from the air current and hurl them centrifugally into the pulverizing zone.

6. A pulverizing apparatus comprising a casing having opposed internal walls and an inlet and a centrally located outlet opening on opposite sides thereof for air and the material to be pulverized, a rotor disk mounted between said openings and spaced peripherally from the casing to provide two communicating pulverizing zones, means to pulverize the material in both zones including a set of beater pegs on the disk interfitting with a set of pegs on the casing wall in the second zone, all of the pegs on the disk in the second zone being relatively short and spaced a considerable distance from the casing wall and the pegs on the casing wall projecting between the pegs on the disk substantially to the rotor, whereby the material may be pulverized between the two sets of pegs adjacent to the disk and air and the pulverized material may pass freely adjacent the casing wall from the periphery of the casing towards the exit.

7. A pulverizing machine comprising a casing having an inlet on one side and a centrally located outlet on the other. a rotor disk between said openings, means cooperating therewith to form first and second grindng zones communicating at the periphery of the disk, including a set of short pegs on the disk interfitting with a set of pegs on the casing in the second zone arranged to pulverize material adjacent the disk and provide a free passage adjacent the casing for the air to pass from the first zone to the outlet and a rejector arm located outside of the grindin zone and revoluble across the entire outl et which is arranged to return coarse material into the path of the revolving egs.

Signed at the city of Coventry, England this twentieth day of August 1925.

CHARLES E. BLYTH.

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