US2371513A - Material cooler - Google Patents

Description

March 13, 1945. J, B, GFFNEY 2,371,512.`-

MATERIAL COOLER Filed sept. 2:5, 1945 -o oo o o I 0 o o o o o TTF-o o o o 0 l 60 oo`ooo ."gipoaooaI Arran/5K5 Patented Mar. i3, 1945 l asians unirse STATES PATENT ferries l Fuller tion of Delaware Company, Catasauqua, Pa., a corpora- Applicatlon September 23, 1943. Serial No. 503,467

6 Claims. (Cl. 34164) This invention relates to material cooling and more particularly to the rapid air quenching oi Portland cement clinker, ore nodules, and lime in varied particle size as issuing from rotary kilns in which the material is burned.

The apparatus of the invention is an improvement upon that of United States Patent No. 2,137,158, granted November 15, 1938, to which reference may be had for a complete statement of the general problem of cooling Portland cement clinker.

The principal cooling elements in the patented structure comprise a series of overlapping, horizontal water-cooled grates, with Vfixed grates alternating with laterally movable reciprocating grates. -The moving grates serve to agitate the bed continuously and to cause the individual parv ticles of material being cooled to be rolled and overturned as they advance toward the discharge port at the lower end of the grate assembly. The

-slope formed by the leading edges of the grates is preferably relatively flat and well within the angle of repose of the material so that incoming particles will not roll freely down over the grates, a slope of about l2 degrees being usually provided.

Each grate is provided with a multiplicity of vertical air ports, which are alternately covered and uncovered, as the moving grates are reciprocated, and air is forced through these ports upwardly through the clinker bed. The xed and moving grates are also vertically spaced, usually about one-quarter of an inch, to provide a horiso that the necessary volume of air can be forced through and between the grates at and adjacent to the entrance to the chamber to reduce the temperature of the material abruptly. When cooling cement clinker, a relatively large proportional the air may bev diverted through the elements of the grate surfaces near the entrance for the material inorder to correct a severe magnesia condition and this procedure may, at times, result in less emcient heat recuperation than that obtainable in modern types of coolers. However, it should be borne in mind that the principal objective is to produce a maximum glass content in the clinker and that even moderate delay in cooling in the region of high temperature results inthe formation of dangerous proportions of periclase.

The rest of the requirement of secondary air is preferably proportioned and distributed through the remainder of the clinker bed to provide for a maximum heat recovery relative to the optimum volume of air. The preheated secondary air passes freely upward to a bustle above the chamber, from which it enters the kiln.

2.5 In addition to the control of cooling rates in zontal air passage through which air is forced continuously at substantially right angles to the flow through the ports and generally in the direction of advance ofthe material. v

Immediately'upon dropping through the chute` from the kiln and entering the cooling chamber,

the material particles are subjected to Vblasts of cold air, and as they are continuously agitated and overturned as they advance from grate to grate, the cold blasts of air impinging upon the particles from two directions provide for abrupt and uniform cooling.

The space in the cooling chamber below the grates forms a wind-box supplied by a fan having the capacity to deliver a volume ofair at least equal to the kiln requirement of secondary air forl combustion and at suiilcient pressure, usually about 5 inches of water, to overcome the resistance of the grates and the material stream. The wind-box is preferably provided with transverse baiiles forming compartments which may be separately supplied with air in varying quantities succeeding portions of the clinlrer bed by the above described proportioning of volume ow of air, the degree of agitation may be modied by adjusting the throw or extent of lateral movement of the moving grates and the rate of travel of the bed and its function, the time of exposure in the cooling chamber, may be modified by changing the rate of movement of the grates.

In using the apparatus incorporating the invention of the above patent, it was found that frequently the material would suddenly flow or cascade down the steps of the cooler to a red hot pile at the bottom. 'I'his action interrupted the continuous operation of the device, caused unevenness of preheating of the'secondary air fed to the kiln. and created a generally unsatisfactory condition interfering with the eiilciency and satisfactory operation of the device. 0ccasionally the large material particles would ride down over the smaller ones, but more frequently the whole body would suddenly slide down in a manner similar to that of an avalanche. The

sliding action seems to be closely associated with any solution allow for such motion and be substantially positive in operation without the need of attention and preferably without adding other moving parts to this particular portion of the device.

The best means of preventing the cascading or avalanche action of the hot material was found to be the addition of an upwardly inclined toe portion to the outer edge of the tread of the step. This toe portion was found to be most satisfactory when of about the same area as the tread of the step, inclined upwardly from the plane of the tread at an angle of about 30 degrees, and provided with air holes for additional more rapid cooling ofthe clinker. While the cascading eil'ect is most prevalent in the upper or hot half of the clinker stream, it is contemplated that the toe portion may be added to all the grates if desired.

For a better understanding of the invention, reference is had to the drawing which is to be taken as illustrative and not as limiting.

Fig. l is a fragmentary elevation in section of the apparatus with some of the conventional parts only partially shown.

Fig. 2 is a plan view of one of the individual grates.

Fig. 3 is a vertical section along line 3-3 of Fig. 2.

A conventional rotary kiln l is normally closed and sealed by a refractory-lined hood 2, having a relatively large circular opening 3 communicating with an arch-shaped refractory lined bustle 4. Bustle 4 is somewhat longer than is usual and is provided with an open bottom 5 registering with a passage 6 opening into cooling chamber 1.

Hot material as discharged from kiln I falls through narrow chute II which is displaced transversely toward the rising side of kiln I. The bottom of chute II is closed by shelf I2 which is air-cooled by means of radiating fins I3. After the material particles have accumulated on shelf I2, and have formed a natural angle of repose, the descending particles which follow are distributed by the pile previously formed and pass through entra-nce I5 of the cooling chamber 1 in which they form an inclined bed resting upon the upper portion of the grate assembly.

The grate assembly comprises alternately xed grates I6 and movable grates I1. Fixed grates I6 are rigidly secured to a stationary frame comprising inclined channels I8 secured by upright supports 20 and 2l to lower frame members 22 which rest on ledges 24. Suitable transverse bracing is provided as at 25 and 26. Movable grates II are mounted on a moving frame comprising inclined side members 29 suitably braced and carrying uprights 32 to which movable grates I1 are secured. Members 29 are movably mounted on axles 33 and 34.

The desired reciprocating motion of the movable frame may be conveniently accomplished by two spaced eccentrics comprising eccentric rods 44 pivotally connected to a horizontal shaft 45 secured to the movable frame members 29. Rods 44 pass through slots in the rear wall of chamber 1 and terminate in straps 48 surrounding the eccentric discs 49. A common crankshaft mounts sprocket Wheel 50 driven through chain 5I by a variable speed motor and speed reducer indicated generally at 52. It will be noted that the grates I1 move in parallel horizontal planes between the fixed grates I6 and that the extent of the movement or throw depends upon the eccentricity of the discs 49 on the crank-shaft.

The' maximum practical advance of the movable grates is substantially one-half their width, at which point the rear edge of each moving grate is covered by the leading edge o! the fixed grate above it, thereby avoiding passage of. line clinker between the grates. It will be understood that the rate of travel of the bed, and consequently its thickness can be varied by changing the speed of the motor 52.

The fixed and moving grates are substantially similar, and may be gray iron castings reinforced by steel rods 53, the forward or leading edges of the fixed grates I6 and the forward and side edges of the movable grates I1 preferably being hardened as by chilling to resist the wear of the highlyabrasive clinker. The forward discharge portion of grates I6 and I'I is provided with an upwardly inclined," smooth-surfaced toe portion which occupies about of the total width of the grate and has a top surface making an angle of about 20 to about 30 with the plane of the grate. At its free edge, the portion has a thickness preferably somewhat more than 50% greater than the thickness of the grate along the opposite edge thereof and the increased thickness of the grate at its forward edge, resulting from the provision of the toe portion. causes the material to fall through a greater distance in passing from one grate to the next. This results in increased cooling action. While in the apparatus shown in Fig. 1, only the grate members near the entrance end of the cooler are provided with toe portions, it will be evident that such grates may be used throughout the cooler, if desired.

Each of the grates is provided with a plurality of ports or orifices 60 substantially perpendicular to its clinker supporting face, conical in shape, and widening downwardly so that they will not be plugged by small particles of clinker. The alter- 40 nate grates are spaced about one-quarter of an inch to form horizontal passageways for air from the lower portion of chamber 1 which forms the wind-box.

The forward or discharge end of the cooling chamber 1 is closed below the grate assembly by a refractory wall 6I upon which the lowermost fixed grate rests. The secondary combustion air is the cooling medium and is supplied to the windbox portion of the chamber 1 through the duct 62 which is in turn supplied by the usual fan, not shown, at a pressure of about five inches of water. The wind-box is preferably provided with at least one transverse baille 63 to form a compartment supplied by the duct 62 through a connection 64. One or more additional bales 68 may be provided to divide the wind-box into additional compartments, whereby the volume flow of air through the remainder of the clinker bed may be proportioned to provide for a maximum of cooling and heat recovery.

The clinker discharge from the lowest grate falls between wall 6I and pivotally supported gate or screen 61, the clinker falling into tunnel 68 from which it is removed by conventional means such as a drag chain 69. Outlets 10 normally closed by slide-gates 'II are provided for the convenient discharge of fine clinker particles and dust which accumulate in the wind-box.

As above indicated, in operation clinker falls from kiln I through chute II onto shelf I2 and forms a relatively fiat inclined bed on the surfaces of grates I6 and I'I. The bed is advanced by the reciprocation of movable grates I1 and is moved forward to the discharge end at wall 8l at a regular though intermittent rate. The thickness asrnm I of the bed is normally from three to six inches and its rate of travel is controlled by the distance. grates I1 move as well as by the` speed of movement. Normally eccentric discs 48 are driven at about four to six revolutions per minute. The individual particles arer subjected to continuous agitation and rolling movements and are subiected to air blasts from three directions.` As the moving grates are advanced and retracted, the ports 60 in the rear portion of each grate save the top one are covered and uncovered alternately. During the rearward movement, the leading edges of the fixed grates I6 force the clinker particles oil the intermediate movable grates I1 onto the fixed grates I6 next below. from which they are subsequently forced during the next forward movement. Any sudden flow or cascading of the molten clinker from rear shelf l2 to wall 6| is entirely prevented by toe portions 54. Furthermore, it has been found that the use of the toe portions on the grates eliminates the necessity of secondary cooling described inthe patent and the aeration of the material and the cooling thereof is so increased by the increase in the fall of the material from one grate to the next that the material can be comfortably picked up at the -last grate in the gloved hand. The use of the grates with the toe portions thus not only prevent avalances of the material through the cooler but also increases the efficiency ofthe cooling action.

Iclaim:

1. In an apparatus for the rapid cooling of heated material, the combination of a cooling chamber having an entrance for hot material at one end and a discharge port at the other. cooling elements in the chamber comprising a series of spaced over-lapping grates, including fixed grates alternating with movable grates, the upper surfaces of the grates serving to support a y bed of material particles. means to limpart reciprocating movement to the movable grates` to agitate and advance the bed, said grates having their forward discharge portion inclined upwardly with respect to the horizontal on a smooth surface to increase the vertical height thereof. whereby .the rapid flowing characteristics of very hot material is overcome to permit proper initial cooling and means to admit air under pressure to the chamber below the grates to provide air blasts owing between the grates and into the heated material.

2. In an apparatus for cooling heated material, the combination of a cooling chamber having an entrance port for the heated material at one end and a discharge port -at the other end, a downwardly inclined support in the chamber having its upper end adjacent the inlet to receive the material, the upper surface of the support serving to support a substantially flat bed of particles, said support comprising two series of spaced, overlapping, transverse grates, the grates lying in stepped relation with fixed grates a1- ternating with movable grates, means for recip rocating the movable grates to cause the material in the bed to travel downwardly along the support', the grates in the lower seriesV of grate-s having flat supporting surfaces, the grates in the upper series of grates having their forwardV and meansl to admit airy under vpressure to the chamber below the grates to provide air blasts iiowing between the grates and into the material. v

3. In an apparatus for cooling heated material, the combination of a cooling chamber havin the bed to travel downwardy along the support, I

the grates in the lower series of grates having flatl supporting surfaces, the grates in the upper series of grates having their forward portion inclined upwardly with respect to the horizontal in a, manner to form a smooth supporting surface, whereby the vertical height of the discharge portion of those grates is increased and rapid movement of the hottest material particles entering the entrance port is inhibited, the grates of each series having air channels therein, and means to admit air under pressure to the chamber below the grates to provide air blasts flowing between and through the grates and into the material.

4. In an apparatus for the rapid cooling of hot material, the combination of a cooling chamber having an entrance for hot material at one endl and a discharge port at the other, cooling elements in the chamber comprising a series of spaced, generally horizontally-extending, overlapping grates, including xed grates alternating with movable grates, the upper surfaces of the grates serving to support a bed of material particles, means to impart reciprocating movement to the movable grates to agitate and advance the bed of material, the forward portion of at least some of said grates being inclined upwardly with respect to the horizontal a distance sulcient to extend beyond the planes of the bottoms of the next preceding grates, whereby such preceding grates, in the relative movement of the grates, push the material on the next succeeding grates up said inclined portions, and over the forward edges thereof, said upwardlyinclined portions inhibiting rapid movement of the. material particles in the direction of their advance, and means to admit air under vpressure to the chamber below the grates to provide air blasts flowing between the grates and into the hot material.

5. In an apparatus for lthe rapid cooling of hot material, the combination of a cooling chamber having an entrance for hot material at one end and a discharge port at the other, cooling elements in the chamber comprising a series of spaced, generally horizontally extending,

- over-lapping grates, fixed grates alternating with movable grates, the upper surfaces of the grates serving to support a bed of material particles,v means to impart reciprocatingmovement to the movable grates to agitate and advance the bed of material, at least some of said grates having rear and forward portions, the upper surfaces of which are in different planes, with the upper surface of the forward portion lof such grates being inclined upwardly with respect to the horizontal a distance suiiicient to extend beyond the plane of the bottoms of the preceding grates,

' the bed of material in a multiplicity of converging jets. y

'8. In combination a cooling grate for cement clinker comprising a base member, downwardly extending mounting portions on each end of said base member, said base member having its for-- ward portion upwardly inclined at an angle of substantially 25 to the plane of said base member and increasing its height more than 50%, said base member and said inclined portion having a plurality of air channels through the faces thereof and a reinforcing member embedded longitudinally in said base member and said upwardly inclined portion.

JOSEPH B. GAFFNEY.

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