US3774854A

US3774854A - Breaker roll mill

Info

Publication number: US3774854A
Application number: US00270162A
Authority: US
Inventors: F Poeschl
Original assignee: Loesche Hartzerkleinerungs und Zementmachinen KG
Current assignee: Loesche GmbH
Priority date: 1972-07-10
Filing date: 1972-07-10
Publication date: 1973-11-27
Anticipated expiration: 1990-11-27

Abstract

Breaker roller mill with horizontally rotating grinding plate and two rotating grinding rollers in a stationary position and a stock food apparatus and on the opposite side of this apparatus a stationary baffle wall extending in curvilinear form in the direction of the grinding path and in the direction of rotation of the grinding plate and whose height permits the stock/gas mixture to flow over said baffle.

Description

United States Patent 191 Poeschl Nov. 27, 1973 BREAKER ROLL MILL [75] lnventor: Franz Poeschl, Reutlingen, Germany [73] Assignee: Loesche Hartzerkleinerungsund Zement-Maschinen KG, Dusseldorf, Germany [22] Filed: July 10, 1972 [21] Appl. No.: 270,162

Related [1.8. Application Data [63] Continuation of Ser. No. 43,164, June 3, 1970,

abandoned.

{52] US. Cl 241/52, 241/80, 241/117 [51] Int. Cl. B02c 13/14 [58] Field of Search 241/52, 79, 79.1, 241/79.2, 8O, 117, 123, DIG. 2

[56] References Cited UNITED STATES PATENTS 1,697,704 1/1929 Wood 241/52 1,832,403 11/1931 Loesche 241/80 X 2,431,746 12/1947 Frangquist.. 2,436,487 2/1948 Sherban.....; 241/117 X Primary ExaminerHarold D. Whitehead Assistant Examiner-E. F. Desmond Attorney-Holman & Stern 5 7 ABSTRACT Breaker roller mill with horizontally rotating grinding plate and two rotating grinding rollers in a stationary position and a stock food apparatus and on the opposite side of this apparatus a stationary baffle wall extending in curvilinear form in the direction of the grinding path and in the direction of rotation of the grinding plate and whose height permits the stock/gas mixture to flow over said baffle.

7 Claims, 7 Drawing Figures PAHENIEDNuv 27 ms Fig. 2

IDVEDIOF 4 rrnxwcrs PATENTEUHUVZT I975 SHEET 3 [IF 3 Fig.7

Inventor:

14 fr: Anrf Y5 BACKGROUND OF THE INVENTION mill is also known.

Since roller mills often operate in close cooperation with larger plants it is possible for cases to occur in which it is desirable for the mill to be fed with a constant stream of stock. This case occurs frequently when furnace exhaust gases are utilised for drying the ground stock. It is a condition for this kind of operation that the furnace can be regulated independently of the downstream connected mill which must therefore accommodate a fluctuating quantity of gas. Since it is appropriate for the mill to remain in constant operation but is required during continuous operation to produce the quantity of stock to be taken up by the furnace it is possible for conditions to arise in which it is desirable for the mill to have the smallest specific work loading at partial loads. It is possible for the prestress of the hydropneumatic suspension of the milling rolls to be taken over automatically at partial loading but in most cases this will have the effect of varying the consistency of the ground stock.

These difficulties in regulation led to the consideration that it is appropriate to incorporate a regulating element at a position not hithertoprovidedfor this purpose in roller mills with two milling rolls, such regulating elements simultaneously providing by means of a screening effect a division of the ground stock into finer and coarser fractions, the coarser fraction being returned for grinding by the shortest possible path. It

has been found that such apparatus successfully permits output regulation with a constant material flow rate or other constant factors and that moreover the subdivision of the stock into finer and coarser fractions at this position under conditions of a substantially identical energy requirement enables a noticeable output of the mill to be achieved. This surprisingresult is based on the observation that if abaffle wall is installed in a partially-fluidised stream of material, the finer fraction flows around a baffle wall in the manner of a flow encountering an obstacle, while the larger and insufficiently ground fractions may be diverted by the baffle wall in a desired direction. A particularly strong regulating effect is achieved by virtue of the shape and di rection impared to the baffle wall.

The provision of baffle walls in breaker roller hills is known. However, in known systems the baffle walls are provided merely to,clear the ground stock from the grinding platen or to re-feed the coarse stock to the grinding platen.

According to the invention a stationary baffle wall,

extending substantially in curvilinear form in the direction of the grinding path is disposed on the opposite side of the grinding plate and extends in the direction of rotation of the grinding plate as far as the pinch gap of a grinding roller and whose height permits the stockgas mixture to flow past it at least along its top edge.

5 According to the invention the baffle wall may also be curved, that is to say it may be constructed in spatially curved form. The inner guide surface of the baffle wall may be parabolic, the greatest curvature being provided approximately at the position of the most intense flow of material. The baffle wall may also be constructed in stream line section.

Finally, according to the invention it is possible for two or more baffle walls to be vertically staggered. It is also possible for two sets of material feed apparatus to be provided, one baffle wall being disposed opposite to the material feed apparatus. In all embodiments it is possible for the baffle wall to be vertically adjustable. According to the invention the baffle wall may be pivotable in parallel to the plane of the grinding platen.

The apparatus according to the invention provides for reliable output control with a constant stock flowrate or other constant factors at the same time providing a noticeable output increase with the same energy requirements.

Embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which:

FIG. 1 is a diagrammatic with two grinding rollers;

FIG. 2 is a diagrammatic side view of a roller mill;

FIG. 3 and 4 are diagrammatic plan views and a sectional view of a bafflewall;

FIG. 5 and 6 show a plan view and section of a further embodiment of a baffle wall;

FIG. 7 is a diagrammatic view of adjusting means.

The diagrammatic view of FIG. 1 shows merely the grinding platen 1 as a plan view, the grinding rollers 2, disposed thereabove and being slightly inclined, material feed apparatus 3 and the contour of the mill housing 6, illustrated merely by a circular line.

FIG. 2 shows as a side view the central parts of a roller mill to the extent to which they are required for an understanding of the invention. As shown in FIG. 1, the grinding platen is referenced with the numeral 1, the grinding rollers with the numeral 2 and the baffle means with the numeral 4. As shown in FIG. 2 the grinding rollers 2 are mounted on rocker levers 15 which in turn are arranged to pivot around a shaft 16. The rocker lever 15 has a shorter arm on which the piston rod 20 acts, said piston rod being driven by the hydraulic cylinder 19. The grinding plate I is driven via a transmission 18.

FIGS. 3 to 6 show plan views and sections of two embodiments of a baffle wall. In FIGS. 3 and 4 the stream of grinding stock is subdivided on striking the baffle wall 4 into afraction 10 of a coarser structure and a fraction 11 of a finer structure. FIG. 4 is intended to show that a rough preclassification takes place on.the baffle wall 4 because the air stream conducts theifiner fractions 4 around the top and bottom of the baffle wall 4 because of the greater floating capability of saidfraction while the coarser fraction 10 is deflected and returned by the shortest possible path to the grinding process thus eliminating the repeated grinding of fine fraction material which is observed in such mills.- Preclassifying of the infed stock has resulted in an increase of output which is substantial compared with the slight efplan view of a roller mill fort. FIGS. 5 and 6 are plan views and a side view of an embodiment of a baffle wall 4'. which is curved, the curvature following substantially that of a parabola and representing a closed cross sectional shape which, according to FIG. 6, facilitates the flow of the time fraction around said baffle wall. FIG. 7 shows the arrangement of an adjustable baffle wall 4". The baffle wall 4" is pivotably mounted on a shaft 5 which in turn is mounted by means of a support on the housing wall 6. The adjusting rod 7, extending through the mill casing 6 is disposed at the other end of the baffle wall and is provided on the outside with a nut for adjustment.

I claim:

1. In a breaker roller mill for grinding a gas fluidized stream of material, said mill having a horizontally rotating grinding platen, two rotating grinding rollers in stationary positions, and at least one stock feed apparatus disposed to one side of the grinding platen between said rollers, the improvement comprising a stationary baffle wall having a top edge and bottom edge, said baffle wall being disposed on the opposite side of the grinding platen from said stock feed apparatus immediately above the grinding platen, said baffle wall extending in curvilinear form substantially in the direction of rotation of the grinding platen to the pinch gap of one of the grinding rollers, said baffle wall spaced above said grinding platen and extending into the path of a stream of material traversing the grinding platen, the distance between the top and bottom edges allowing a flowing around of the finely ground stock particles in said fluidized stream over at least the top edge of the baffle wall, while coarser stock particles are carried to the pinch gap-of the grinding rollers for further grinding.

2. In a breaker roller mill for grinding a gas fluidized stream of material, said mill having a horizontally rotating grinding platen, two rotating grinding rollers'in stationary positions, and at least one stock feed apparatus disposed to one side of the grinding platen between said rollers, the improvement comprising a stationary baffle wall disposed on the opposite side of the grinding platen from said stock feed apparatus immediately above the grinding platen, said baffle wall extending in curvilinear form substantially in the direction of rotation of the grinding platen to the pinch gap of one of the grinding rollers, said baffle wall being spaced above said grinding platen and extending into the path of a stream of material traversing the grinding platen whereby finely ground stock particles in said fluidized stream will be carried past said baffle wall over at least an upper edge thereof, while coarser stock particles are carried to the pinch gap or the grinding rollers for further grinding.

3. In a breaker roller mill for grinding a gas fluidized stream of material, said mill having a horizontally rotating grinding platen, two rotating grinding rollers in stationary positions, and at least one stock feed apparatus disposed to one side of the grinding platen between said rollers, the improvement comprising a stationary baffle wall having a top edge and bottom edge, said baffle wall being disposed on the opposite side of the grinding platen from said stock feed apparatus immediately above the grinding platen, said baffle wall extending in curvilinear form substantially in the direction of rotation of the grinding platen to the-pinch gap of one of the grinding rollers, said baffle wall spaced above said grinding platen and extending into the path of a stream of material traversing the grinding platen, said baffle wall-being convex between the top and bottom edges to allow finely ground stock particles in said fluidized stream to be carried past said baffle wall over at least the top edge thereof, while coarser stock particles are carried to the pinch gap of the grinding rollers for further grinding.

4. The breaker roller mill according to claim 3, characterized in that the baffle wall is curved in the direction perpendicular to the plane of the grinding platen.

5. The breaker roller mill according to claim 3, characterized in that the baffle wall includes an inner guide surface facing the stock feed apparatus and constructed in parabolic form, the greatest curvature of said guide surface being located approximately at the position of the most intense flow of stock in the gas stream.

6. The breaker roller mill according to claim 4, characterized in that the baffle wall has a streamlined section.

7. The breaker roller mill according to claim 3, characterized in that the baffle wall is pivotable parallel to the plane of the grinding platen.

Claims

1. In a breaker roller mill for grinding a gas fluidized stream of material, said mill having a horizontally rotating grinding platen, two rotating grinding rollers in stationary positions, and at least one stock feed apparatus disposed to one side of the grinding platen between said rollers, the improvement comprising a stationary baffle wall having a top edge and bottom edge, said baffle wall being disposed on the opposite side of the grinding platen from said stock feed apparatus immediately above the grinding platen, said baffle wall extending in curvilinear form substantially in the direction of rotation of the grinding platen to the pinch gap of one of the grinding rollers, said baffle wall spaced above said grinding platen and extending into the path of a stream of material traversing the grinding platen, the distance between the top and bottom edges allowing a flowing around of the finely ground stock particles in said fluidized stream over at least the top edge of the baffle wall, while coarser stock particles are carried to the pinch gap of the grinding rollers for further grinding.

2. In a breaker roller mill for grinding a gas fluidized stream of material, said mill having a horizontally rotating grinding platen, two rotating grinding rollers in stationary positions, and at least one stock feed apparatus disposed to one side of the grinding platen between said rollers, the improvement comprising a stationary baffle wall disposed on the opposite side of the grinding platen from said stock feed apparatus immediately above the grinding platen, said baffle wall extending in curvilinear form substantially in the direction of rotation of the grinding platen to the pinch gap of one of the grinding rollers, said baffle wall being spaced above said grinding platen and extending into the path of a stream of material traversing the grinding platen whereby finely ground stock particles in said fluidized stream will be carried past said baffle wall over at least an upper edge thereof, while coarser stock particles are carried to the pinch gap or the grinding rollers for further grinding.

3. In a breaker roller mill for grinding a gas fluidized stream of material, said mill having a horizontally rotating grinding platen, two rotating grinding rollers in stationary positions, and at least one stock feed apparatus disposed to one side of the grinding platen between said rollers, the improvement comprising a stationary baffle wall having a top edge and bottom edge, said baffle wall being disposed on the opposite side of the grinding platen from said stock feed apparatus immediately above the grinding platen, said baffle wall extending in curvilinear form substantially in the direction of rotation of the grinding platen to the pinch gap of one of the grinding rollers, said baffle wall spaced above said grinding platen and extending into the path of a stream of material traversing the grinding platen, said baffle wall being convex between the top and bottom edges to allow finely ground stock particles in said fluidized stream to be carried past said baffle wall over at least the top edge thereof, while coarser stock particles are carried to the pinch gap of the grinding rollers for further grinding.