Патент USA US2126081код для вставки
Aug. 9, 1938. E. G. BAILEY ET AL 2,126,081 PULVERI ZER Filed March 23, 1934 0 / 33 ymw MW HY 57 Erv/n G. Bai/e dg .B . V: M . M .m T a E Y.‘r w Patented Aug. 9, 1938 2,126,08l UNITED ‘STATES PATENT OFFICE ' 2,126,081 PULVERIZER Ervin G. Bailey, Easton, Pa., and Ralph M. Hard grove, West?eld, N. J., assignors to The Bab cock & Wilcox Company, Newark, N. J., a cor~ poration of New Jersey Application March 23, 1934, Serial No. 716,936 4 Claims. (01. 83-45) Our present invention relates to apparatus for grinding capacity. This undesirable distribution pulverizing materials, such as coal, cement, rock products and ore, and more particularly to pul verizers wherein the material to be pulverized 5 passes through a plurality of successive grinding stages, each formed by a pair of Vertically spaced of the grinding load naturally results in a de crease in the degree of ?neness of the product. As pulverizers of the character described are nor mally associated with classifying apparatus for relatively rotatable grinding rings between which separating and returning the coarse particles to the pulverizer, the amount of coarse particles is positioned an orbital row of rolling grinding returned correspondingly increases, with a corre elements. sponding increase in the cost of grinding per ton of product of the desired degree of ?neness. The rate of passage of the material through the upper grinding stage, and thereby the depth of material therein and the amount of the circulat ing load, may be controlled by providing flow re stricting means at the outer or discharge side of 15 In operation the grinding elements move over the surface of the grinding rings and eifect a grinding action on any material between the contacting surfaces. When the relative movement between the grinding‘ parts is pro duced by having the lower grinding ring rotary 15 and the upper grinding ring non-rotary, the ma terial undergoing pulverization is advantageously the upper grinding stage, as disclosed, for ex supplied to the inner side of the row of grinding ‘ ample, in, our prior joint patent with Perry R. ‘ , ‘ elements and passed outwardly therethrough. Cassidy, No. 2,071,379. , The outward flow of material may be partly due Heretofore, as shown in our said prior patent, 20 ‘to a head of material at the inner side ofthe such flow controlling provisions have consisted 20 row, but is mainly due to the centrifugal effect exerted on the material by the rotation of the lower grinding ring, over the upper surface of which the material passes, and the grinding ele 25 ments,‘ and to the displacement effect of the roll ing grinding elements on some of the material in their path of rotation. At economical speeds, the combined effects normally result in a too rapid of an annular basket or plate forming a restrict flow of material across the grinding area. In a multi-stage pulverizer, in which the grind ing stages are vertically spaced and formed by top, intermediate and bottom grinding rings be tween the successive pairs of which are respec tively positioned upper and lower circular rows 35 ‘of metallic grinding balls having a relative rota tion with respect to the grinding rings contact ing therewith due to a ?oating drive connection to the intermediate ring, thelmaterial passes out “ 40 ed annular gap with the rotary intermediate ring in the path of flow of the material passing from the upper grinding stage to the lower stage. Such means have been found objectionable because of 25 their inherent inability to maintain a uniform ?ow controlling effect for an extended period of operation and the tendency of the material to pack at the gap. This lack of'uniformity of con trol is mainly due to changes in position of the intermediate ring relative to the gap forming provisions with wearing of the lower grinding ring and balls and Wear on the gap-de?ning edge of the basket or ledge plate due to friction of the material, which is increased by the rotation of the adjacent intermediate ring. The variations in size of the flow controlling gap due to these various causes may be somewhat offset by read wardly through the upper grindingv stage and justing the position of the gap-forming provi inwardly‘ through the lower stage; The mate sions. rial tends to pass at a higher speed through the upper grinding stage due to the centrifugal force imposed thereon in that stage, while the cen trifugal effect, if any, on the material in the low 45. er stage will oppose its passage therethrough. The depth of material in a grinding stage of the character described is an important factor af fecting the amount of grinding accomplished therein, as little, if any, grinding will be done on 50 the upper ring of the stage if the depth of mate rial falls below a certain value. Thus with a too rapid flow of material through‘the upper grind ing stage, those grinding parts will do less grind ing than they are capable of doing, while the 55 lower grinding stage will be loaded beyondv its The proper adjustment however cannot be accurately determined without interrupting the operation of the pulverizer, and moreover is limited in extent. , , , ' The general object of the present invention is the provision of pulverizers of the character de scribed with improved provisions for controlling the ?ow therein of material undergoing pulveri zation. A more speci?c object is the provision of pulverizer ?ow controlling means which will maintain a uniform flow controlling effect re 50 gardless of changes in size or position of the grinding parts and are not subjected to undue wear in operation. A further speci?c object is the‘provision of a ?ow controlling dam on a pul verizer rotary grinding ring having an outward 55 2 2,126,081 flow of material thereon so constructed and ar ranged relative to the grinding area on the ring to substantially neutralize the centrifugal effect thereof on the material undergoing pulverization. A further speci?c object is the provision of a multi-stage air-swept pulverizer of the general character described having a flow controlling dam on the intermediate rotary ring thereof associat ed with means for facilitating the separation of 1 O ?nes before the material reaches the classi?er. The various features of novelty which charac—' terize our invention are pointed out with par ticularity in the claims annexed to and forming a part of this speci?cation. For a better under standing of the invention, its operating advan tages and speci?c objects attained by its use, ref erence should be had to the accompanying draw ing and descriptive matter in which we have row of balls into the lower or discharge section of the casing, to which a discharge conduit 45 is connected. The discharge of the material is facilitated by a series of sweep blades 46 mounted on the drive yoke 31. In accordance with our present invention, de sirable grinding conditions are continuously maintained in each grinding stage with high capacity operation and low power consumption by employing flow controlling or load distribut ing provisions which are constructed and ar ranged to function uniformly in operation over a prolonged period. One of the novel features of our flow control ling provisions is their arrangement on and ro ' lustrated and described various embodiments tatable with the intermediate ring 32, whereby of our invention. the troubles heretofore due to wear on the sta ' Of the drawing: tionary ledge plate in proximity to the rotary Fig. l is a sectional elevation of a gravity dis charge pulverizer incorporating our invention; Fig. 2 is an elevation and Fig. 3 is a plan view of the adjustable skirt shown in Fig. 1; and Fig. 4 is a fragmentary view illustrating a modi ?ed dam construction. The gravity-discharge type pulverizer illus trated in Fig. 1 comprises a metallic casing 30 .having a cylindrical upper section enclosing the ‘material pulverizing parts which include a non rotary top grinding ring 3], a rotary intermediate grinding ring 32, and a non-rotary bottom grind; ing ring 33 spaced vertically in the casing, a cir ; ‘cular row of rolling grinding elements, prefer ably in the form of heavy metallic balls 34, be tween the top and intermediate grinding rings and a concentric row of grinding balls 35 between the intermediate and bottom grinding rings. A 40 floating drive connection for the intermediate grinding ring from a main drive shaft 36 axially ring will be eliminated. In the drawing we have illustrated various forms of flow controlling pro visions of this type. The flow control provisions consist of means 25 forming an adjustable dam on the periphery of the rotary intermediate ring 32, and are based upon our theory that there is a slope correspond ing to the speed of the intermediate ring and coe?icient of friction of the material undergoing pulverization, on which the particles of material will be in equilibrium with the component forces of gravity and friction balancing the component of centrifugal force. Under such conditions, the flow of material over the top of the dam will be 35 due to the push or displacing effect thereon of the balls 34 and the discharge of material will increase as the level in the grinding zone tends to build up. end of the drive shaft and having driving arms' If the dam slope be too low the material will 40 ?ow at too great a rate, and if too high the mate rial will be retained in the top ring for too long a period, and thereby lower the capacity, in crease the power consumption of the pulverizer, 38 thereon each positioned between andverti cally movable relative to a pair of plates 39 on and throw an excessive amount of the grinding 45 load on the upper row of balls tending to cause arranged relative to the ball rows is effected through a drive yoke 37 mounted on the upper the inner side of the intermediate grinding ring. Similar parts provide a ?oating non-rotary con-7 nection between the top grinding ring and the casing 30, as shown. The adjacent faces of the several grinding rings are formed with races or tracks along which the corresponding rows of balls move. A substantial grinding pressure is ordinarily applied to the upper side of the top grinding ring 3| by a series of helical pressure springs 46 arranged in a circular row on the top grinding ring, as indicated in Fig. l. The spring pressure is externally adjusted in accordance with the hardness of the material undergoing (30 pulverization. The material to be pulverized is delivered to the upper part of the casing through one or more feed spouts 42 projecting through the casing top plate 4|. ' . The feed spouts 42 deliver the material cen trally of the top grinding ring, Where‘it is di rected to the inner side of the upper row of balls 34 by a conical cover plate 43 mounted on the intermediate grinding ring. The material will pass substantially spirally outward on the inter, 70 -mediate grinding ring and through the upper row of balls, and is pulverized thereby. The material pulverized in the upper grinding stage drops to the outer side of the lower row of grind Ci inwardly through the lower row of balls 35. The material is further ground in the lower grinding stage and drops from the inner side of the lower ing balls. The partly pulverized material drop ‘;ping to the lower'grinding stage is fed by gravity the material to pack therein. In the construction illustrated in Figs. 1 to 3, the dam is formed by a cylindrical ledge plate 57 mounted on the periphery of the intermediate 50 ring and carrying an adjustable skirt section 58 formed by a plurality of overlapping curved plates 59, each of which is provided with verti cally elongated slots 69 through which project bolts 6| carried by the ledge plate 51. The ad- _ justable skirt section is held in any of its posi tions within its range of adjustment by curved washers 62 and nuts 63 carried by the bolts. The raising or lowering of the skirt correspond ingly varies the effective angle of the dam rela tive to the grinding race. With this arrangement a ledge plate of a height corresponding to the ' minimum angle calculated may be mounted on‘ the intermediate ring and the most desirable angle within that range determined experimen tally by varying the height of the skirt. Small variations in the height of the dam have been‘ found to cause substantial variations in the pul verizer capacity, ?neness-of the output, and power consumption. For example, an increase 70 in height of the dam of approximately two inches was found to substantially lower the ca pacity and ?neness of the product and increase the power consumption 40% as compared with ' the results obtained with the lower height. The 7511.: 3 2,126,081 cylindrical ledge plate 51 may be detachably inner side of said row of elements, a circular ledge mounted on the grinding ring, as in Figs. 1 to 3, or integrally formed thereon as shown in Fig. 4. With the various forms of flow controlling pro; visions disclosed, the pulverizing load will be de~. sirably distributed so that under varying load conditions, the depth of material in the upper grinding stage will remain substantially the same. By this arrangement, a substantially uniform. and 10 predetermined grinding effect will be given to the material in the upper grinding stage, and a fur ther grinding supplied in the lower stage. The grinding load in the several stages can be thus proportioned so that none of the stages will be 15 overloaded with a consequent decrease in the degree of ?neness of the product and increase in circulating load, or underloaded with a conse~ quent decrease in pulverizer capacity and in~ creased wearing or‘ the grinding parts. While in accordance with the provisions of the 20 statutes we have illustrated and described herein the best forms of our invention known to us, those skilled in the art will understand that changes may be made in the form of the appa 25 ratus disclosed without departing from the spirit of the invention covered by our claims, and that certain features of our invention may some times be used to advantage without a correspond ing use of other features. We claim: 30 1. A pulverizer comprising a casing having an inlet for material to be ground and an outlet for ground material, a grinding stage having an out ward ?ow of material therethrough and including an upper grinding ring, a rotary lower grinding ring movable relative thereto, and an orbital row of rolling grinding elements positioned between said grinding rings, means for supplying material to be ground to the inner side of said row of ele 40 ments, means forming an annular dam, on said rotary grinding ring at the outer side of and ex tending above the centers of the elements in said row, said dam being radially spaced throughout its height from said vrow of elements, and means 45 for varying the effective height of said dam to regulate the discharge and ?neness of the mate rial leaving said grinding stage including a sec tional skirt forming the upper portion of said dam, and means for varying the position of said 50 skirt. 2. A pulverizer comprising a casing having an inlet for material to be ground and an outlet for ground material, a grinding stage having an out ward ?ow of material therethrough and includ ing an upper grinding ring, a rotary lower grind ing ring movable relative thereto, and an orbital row of rolling grinding elements positioned be tween and contacting with said grinding rings, means for supplying material to be ground to the plate on the periphery of said rotary grinding ring forming a circumferential dam on said rotary grinding ring at the outer side of and radially spaced throughout its height from said row of "It elements, and means for varying the height of said dam to regulate the amount and ?neness of the material discharging from said grinding stage including an upper skirt section adjustably 10 mounted on said ledge plate. 3. In a pulverizer comprising a casing having an inlet for material to be ground and an outlet for ground material, an upper grinding stage having an outward flow of material therethrough and including a rotary grinding ring and an or bital row of rolling grinding elements positioned thereon, a lower grinding stage receiving material discharging from said upper grinding stage, means for supplying material to be ground ‘to the inner side of said row of elements, an adjustable flow controlling dam mounted on said rotary grinding ring at the outer side of and radially spaced throughout its height from said row of ele ments, and means for varying the effective height of said dam for regulating the amount and ?ne 25 ness of the material delivered to said lower grind ing stage including a sectional skirt forming the upper portion of said dam, and means for vary ing the position of said skirt. 4. In a pulverizer comprising a casing having 30 an inlet for material to be ground and an outlet for ground material, an upper grinding stage hav ing an outward ?ow of material therethrough and including a non-rotary top grinding ring, a ro tary intermediate grinding ring movable relative thereto, and an orbital row of rolling grinding elements positioned between said top and inter mediate grinding rings, a lower grinding stage receiving material discharging from said upper grinding stage and having an inward ?ow of ma 40 terial therethrough and including said rotary in termediate grinding ring, a non-rotary bottom grinding ring, and an orbital row of rolling grind ing elements positioned between said intermediate and bottom grinding rings, means for supplying material to be ground to the inner side of said upper row of elements, a circular ledge plate on the periphery of said rotary grinding ring forme ing a circumferential dam on said intermediate grinding ring at the outer side of and radially 50 spaced throughout its height from said upper row of elements, and means for varying the height of said dam to regulate the amount and ?neness of the material delivered to said lower grinding stage including an upper skirt section adjustably 55 mounted on said ledge plate. ERVIN G. BAILEY. RALPH M. HARDG'ROVE.