US1649148A - Coal-pulverizing machine - Google Patents

Description

c. E. BLYTH.

COAL PULVERIZ ING MACHINE Filed April 13. 1926 2 Sheets-Sheet 2 itl Patented CHARLES EDWARD BLYTH, 0F STOCKTON. NEAR RUGBY, ENGLAND, ASSIGNOR TO ALFRED HERBERT LIMITED,OF BUTTS, COVENTRY, ENGLAND, A BRITISH COM- JPANY.

COAL-PULVERIZING MACHINE.

Application led April 13, V1926, Serial No.

rll`his invention relates to coal and similar pulverizing machines, of the type shown in my prior patent Reissue No. 16,229, in which a stream of air passing through the machine carries the finely powdered coal in suspension, whilst means are provided to return to the pulverizing chamber such particles .of coal as have not attained a suiiicient degree of iineness, and its object is to provide mechanism for this purpose which will be effective and inexpensive as well as easy to renew it' necessary. i

In such apparatus, a rotor disk is mounted centrally of the casing between an inlet for airand coarse material and a centrally located outlet to provide two pulverizing zones which communicate annularly around the periphery of the rotor. The disk is pro- `vided with rows of pegs on cach side which interfit and cooperate with rows of stationarv pegs on the two opposed casing walls. yllhe coarse material is ground preliminarily in the inlet zone and is then drawn by a fan adjacent the outlet around the disk and into the final pulverizing zone. Here the Inaterial must be subjected to the impacts of the rapidly revolving pegs on the rotor as it is drawn inwardly towards the centrally located outlet.

According to this invention, in the eXit from the pulverizing chamber is employed a rejector device constituted by one or more rotating members adapted to traverse the outgoing stream and to throw back into the pulverizing mechanism the heavier particles of coal. Thus until such particles attain the necessary degrl of tineness they are repeatedly returned into the pulverizer tor further treatment.

A ring adapted to guide the path of the reJected particles mayvalso be provided to increase the e'ectiveness of the rejector device in returning the larger coal particles to the pulverizer mechanism.

ln the accompanying drawings, illustrating the application ot the invention to a lrnown kind of pulverizing machine,

Figure 1 is a diagrammatic sectional view of the machine,

Figure 2 is a fragmentary view of apart oit' the machine showing one form of rejector device, to a larger scale than Figure 1, and

.Figure 3 is an end view of Figure 2.

101,805, and'in Great Britain May is, 1925.

The machine shown diagrammatically in Figure 1 colnprises a pulverizing chamber 2. having' fixed beaters 3 and rotating beaters 4 carried by a main shaft 5 on which also is mounted a `fan (not shown) located in a casing 6 beside the pulverizer chamber.

Coal is fed through the passage 7 and at the lower part 8 encounters an upward draught ot air created by the fan, which sweeps it through the branch 9 into the pulverizing chamber 2, from which it passes eventually by way of a central exit aperture 10` into the fan casing, and thence to the burner. I n u It is at this exit aperture 10 that it is 1mportant not only to prevent the discharge of such particles of coal as are not sutiicientlv reduced in-'size, but also to provide for their return to the pulverizing chamber for further treatment. Y

Accordingly, therefore, the rejector dcvice is a rotating striker in the form of a4 part ot' the pulverizer.

The shape of the blade may be such that its root 13 is in the plane of the exit aperture 10, this being provided in a diaphragm plate 14 dividing the pulverizing chamber from the fan chamber, whilst the tip 15 of the blade is within'the pulverizing chamber itself. A screen or guide ring 16-may be yarranged aroundthe edge of the exit aperture on the side towards the pulverizer, so that the tip of the blade is within the ring. The'inner face of the ring may be flared or belled outwardly, as at 17, 'towards the pulverizing chamber, and this serves to guide back into the latter the heavier particles of coal upon which the blade acts. rlhe screen ring may be provided with a radial flange 18 to enable it to be detachably mounted upon the diaphragm plate 14, or on a plate 19 to which the fixed beaters 3 are attached.

The blade may be ot channel section with the open part 20 ot the channel as the lead ing. side,.and the depth of the channel may increase progressively :trom the root to the tip. Also the blade, and particularly the bottom wall oia its channel would be curved backwardly of its direction of rotation (indicated by the arrow) in the manner of a centrifugal tan blade. the blade at the root, the side flanges ot the To give stiffness to channel may be extended on each side of the portion forming the base of the channel, and/orl there may be a stilfening web 21 behind it, and a laterally projecting flange or base plate Q2 may be provided at the base to enable the blade to be secured radially to thehub member l2 or the like on the shaft 5 which carries it. One blade alone generally suffices, but two, three (as shown) or more may be employed if desired.

In action, the pulverized coal passes through the aperture 10 from the pulver-izing chamber into the fan chamber, and the rotating striker or blade 11 traverses the outgoing stream and acts upon the heavier particles of coal, flinging them back into the mechanism within the pulverizing chamber.

lVith this arrangement a very simple and effective device is provided for rejecting the heavier particles of fuel and for returning them into the pulverizingnmechanism for further treatment, whilst the construction employed is initially inexpensive and also cheap to renew. Furthermore, the use of balles or other devices which would obstruct the outflow of the finely pulverized material is avoided.

What I claim as my invention and 'desire to secure by Letters Patent of the United States isz- 1. A pulverizing apparatus comprising a casing having a centrally located outlet, 1mpact members mounted to revolve substantially concentrically with the outlet, means for introducing air and material to be pulverized to the peripheral zone surrounding the impact members, means to move the air and pulverized material towards the outlet, and radially projecting rejeetor blades mounted to revolve close to the outlet, each of which has an open ended substantially radial channel which slopes inwardl)v and is arranged to scoop coarse material from the air current passing the blades and hurl it inwardly towards the impact members.

2. A pulverizing -apparatus comprising a casing having an inlet for airand coarse material and a centrally located outlet, impact members revoluble about the outlet to pulverize the material l'ed thereto. and a radially projecting rejector blade mounted to revolve close to the outlet and scoop coarse particles from the air current, said blade having a channel which faces in the direction of revolution and which increases in depth from its inner to its outer end.

3. A rejector for use in a pulverizing apparatus comprising a channel shaped member provided with a laterally projectin base plate integral therewith arranged to [be secured to a rotatable shaft, the channel of said member being open at its outer end so that material caught thereby may be hurled outwardly therefrom.

4. A rejector for use in a pulverizing ap paratus comprising a channel shaped member adapted to revolve and scoo n coarse ma terial from an air current Wiich is provided with a laterally projecting base plate arranged to be secured to a rotatable shaft, the channel shaped member being so shaped that the bottom of the channel inclines backwardly with respect to a radial line and its direction of revolution.

In testimony whereof I have signed my name to this specification.

CHARLES EDWARD BLYTH.

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