WO1992011090A1

WO1992011090A1 - A pulverizing chamber of a counterjet pulverizer

Info

Publication number: WO1992011090A1
Application number: PCT/FI1991/000400
Authority: WO
Inventors: Jouko Niemi
Original assignee: Oy Finnpulva Ab
Priority date: 1990-12-19
Filing date: 1991-12-19
Publication date: 1992-07-09
Also published as: FI906266A; FI906266A0; AU9060191A; FI86514B; EP0561897A1; FI86514C; CA2098500A1

Abstract

This invention relates to a pulverizing chamber of a counterjet pulverizer, which chamber is mainly cylindrical and at least two conically arranged, to a common point (2) directed accelerating nozzles (1) terminate at it, the inner walls of which pulverizing chamber are made of a wearing-resistant special material. The invention is characterized in that the pulverizing chamber comprises a fixed basal part (3), in the vicinity of whose open end the accelerating nozzles (1) terminate, as well as of an exchangeable wearing ring (5) mounted rotatably on this open end, whereby the contact surfaces (6) of the basal part (3) and the wearing ring (5) are formed as sliding surfaces.

Description

A pulverizing chamber of a counterjet pulverizer

This invention relates to a pulverizing chamber of a counter et pulverizer, which chamber is mainly cylindrical and at least two conically arranged, to a common point directed accelerating nozzles terminate at it, the inner walls of which pulverizing chamber are made of a wearing-resistant special material.

In such a counterjet pulverizer, the pulverization occurs mainly autogenously in a pulverizing chamber having a small volume, into which the material to be pulverized flows at a high speed via the accelerating nozzles of the pulverizer and supported by a working gas. The gas/material jets impact against eacht other at their common intersection, whereby the pulverization of material particles is caused by the impact effect. The pulverizing nozzles are arranged slightly conically relative to each other such that the material particles would penetrate into the opposite nozzles or nozzle to an extent as low as possible.

The particles, which do not crush at the intersection of the gas/particle jets, impact against a wall of the pulverizing chamber at a high speed, which causes wearing of the wall especially in those parts of the pulverizing chamber, which are located on the opposite side of the orifice of the nozzle, and in the axial direction between the intersection of the gas/material jets and the outlet opening of the pulverizing chamber. Because of this, the pulverizing chamber must be made of especially wearing- resistant special materials, which are expensive and difficult to fabricate and treat.

The object of the present invention is the entension of the operating life and the facilitation of the fabrica¬ tion of a pulverizing chamber of a counterjet pulverizer. In accordance with the invention, this may be solved such that the pulverizing chamber comprises a fixed basal part, in the vicinity of whose open end the accelerating nozzles terminate, as well as an exchangeable wearing ring mounted rotatably on this open end, whereby the contact surfaces of the fixed part and the wearing ring are formed as sliding surfaces.

The other characteristics of the invention appear from the enclosed claims 1 to 9.

The invention is next described in more detail with reference to the accompanying drawing, in which

Fig. 1 is an axial sectional view of the inventive pulverizing chamber, in which certain alternative embodiments of different components are shown by way of example, and

Fig. 2 shows the pulverizing chamber of Fig. 1 seen from the top.

Fig. 3 is a more detailed side elevation of one certain preferred embodiment of the invention as an axial section, in which the attachment of the accelera¬ tion nozzle is shown.

The pulverizing chamber of the counterjet pulverizer is mainly cylindrical and at least two conically arranged, to a common point 1 directed accelerating nozzles 2 terminate at it, which are arranged slightly conically relative to each other such that the material particles would penetrate into the opposite nozzle 1 to an extent as low as possible. Around this intersection 2 an actual wearing zone is formed. The inner walls of the pulveri¬ zing chamber are subjedted to a very high wearing stress at least at those points, against which the material particles penetrating uncrushed through the pulverizing zone 2 impact. Because of this, the inner walls of the pulverizing chamber must be made of especially wearing- resistant special materials, which are expensive and difficult to fabricate and treat. By means of the solution according to the invention, it has been possible to multiply the operating life of the pulverizing chamber at the same time as its fabrication costs at least in somes cases have considerably decreased. Such a good result is achieved when the pulverizing chamber is fabricated such that it comprises a fixed basal part 3, in the vicinity of whose open end are arranged inlet openings 4 for the orifices of the accelerating nozzles 1. At the open end of the basal part 3 an exchangeable wearing ring 5 is rotatably arranged, whereby the contact surfaces of the basal part 3 and the wearing ring 5 are formed as sliding surfaces 6.

The inventive pulverizing chamber is used such that at intervals of a couple of hundreds of operating hours, depending on the material to be pulverized, the wearing ring 5 of the pulverizing chamber is rotated by some degrees around its axis, whereby worn sections move away from the point where the wearing is at its highest. The stepwise rotation of the wearing rings can be performed so many times at said intervals that the first worn sections enter the following point subjected to heavy wearing, whereby the wearing ring must be replaced with a new one. If the wearing in the axial direction is very limited, it is preferable to design both end surfaces of the wearing ring 5 such that the wearing ring 5 can still be turned around, whereby the operating life of the wearing ring is duplicated.

The sliding surfaces 6 have to be directed so that the gas/material jets rapidly flowing from the accelerating nozzle 1 cannot penetrate into them, whereby the most simple alternative is to arrange them completely radial, but in this case the sliding surfaces 6 do not facilitate the concentration of the pulverizing-chamber parts 3 and 5.

If a built-in concentration capacity is desired for the construction, the sliding surfaces 6 may be e.g. designed in the form of a truncated cone, or if a very accurate concentration is necessary, the sliding surfaces 6 may be designed such that one sliding surface 6 has a longitudinal groove and the other, or opposite sliding surface 6 has a ridge that completely fits into this groove, as shown on the right-sided side wall of Fig. 1. If a heavy-wearing material is pulverized with the counterjet pulverizer, it is useful to fabricate both the basal part 3 and the wearing ring 5 from the same special material, but if the wearing concentrates only on those points of the walls of the pulverizing chamber, which are located on the opposite side of the orifice of each pulverizing chamber 1 and in the axial direction, with respec to the intersection of the gas/matarial jets, on the side of an outlet opening of the pulverizing chamber, the basal part 3 may be fabricated preferably from steel.

If wearing occurs in a very limited area, the pulverizing chamber may be comprized of several wearing rings 5, whereby the wearing ring, which is subjected to heavier wearing, is rotated more often and replaced at more frequent intervals than a wearing ring 5 located in a more protected space.

For keeping the different parts 3, 5 together, it is preferable that the entire pulverizing chamber is mounted inside a separate frame structure 8.

The drawing shows two alternative embodiments of how the accelerating nozzles 1 are brought into the pulverizing chamber. If the material to be pulverized is a heavily- wearing material, the right-sided solution is preferable, since it is capable of protecting the ends of the accelerating nozzles 1 from wearing excessively. If, by contrast, a softer material is pulverized or if the material to be pulverized is by its particle size very fine-powdered, the left-sided solution is better, whereby also the ends of the accelerating nozzles may be brought closer to the pulverizing zone.

The pulverizing chamber may be made by its construction either fully circular or brought into a form of a regular polygon. In the latter case, the number of sides of the polygon defines how many degrees the wearing ring must bo rotated at a time.

The attachment of the accelerating nozzles 1 to the frame structure 8 and an accurate concentration with respect to the intersection 2 may be preferably realized such that at each end of each accelerating nozzle 1 is arranged a pair of 0-rings 10, surrounding the accelerating nozzle 1 and adjustable by means of a clamping ring 9. This solution also effectively prevents the entry of dust into the surrounding space at the same time as the structure acts as an effective damper for vibrations and a possible resonance.

Claims

1. A pulverizing chamber of a counterjet pulverizer, which chamber is mainly cylindrical and at which at least two conically arranged, to a common point (2) directed accelerating nozzles (1) terminate, the inner walls of which pulverizing chamber are made of a wearing-resistant special material, characterized in that the pulverizing chamber comprises a fixed basal part (3), in the vicinity of whose open end the accelerating nozzles (1) terminate, as well as of an exchangeable wearing ring (5) mounted rotatably on this open end, whereby the contact surfaces (6) of the basal part (3) and the wearing ring (5) are formed as sliding surfaces.

2. A pulverizing chamber according to Claim 1, characterized in that both end surfaces (6) of the wearing ring (5) are of the same shape, whereby the wearing ring (5) may be turned around.

3. A pulverizing chamber according to Claim 1 or 2, characterized in that the sliding surfaces (6) are radial or extend conically.

4. A pulverizing chamber according to Claim 3, characterized in that one sliding surface (6) has a longitudinal groove and the other one has a ridge that completely fits into said groove.

5. A pulverizing chamber according to any of the preceding Claims, characterized in that the basal part (3) and the wearing ring (5) are made of same material.

6. A pulverizing chamber according to any of the preceding Claims 1 to 4, characterized in that the basal part (3) is made of ordinary steel and the wearing ring (5) is made of a special material.

7. A pulverizing chamber according to any of the preceding Claims, characterized in that it has at least two wearing rings (5) placed on top of each other.

8. A pulverizing chamber according to any of the preceding Claims, characterized in that the basal part (3) and the wearing ring (5) are mounted on a separate frame structure (8).

9. A pulverizing chamber according to Claim 8, characterized in that the attachment of the accelerating nozzles (1) to the frame structure (8) and an accurate concentration with respect to the intersection (2) are realized such that at each end of each accelerating nozzle (1) is arranged a pair of 0-rings (10), surrounding the accelerating nozzle (1) and adjustable by means of a clamping ring (9).