DE7300113U - MILL FOR CRUSHING PARTICULATE MATERIAL - Google Patents

Description

Mill for the fine comminution of particulate matter material

The invention relates to a mill for the fine comminution of particulate material and , in particular, relates to a mill of the type having a cylindrical chamber in which the particulate material entrained in a gas is subjected to a high-speed circular motion, comminution taking place by collisions between the particles, and removing the crushed particles in a gas stream in the center of the mill . A predominant part of the high pressure gas is introduced into the chamber through tangentially inclined nozzles in the curved peripheral walls of the mill chamber.

The mill according to the invention is particularly advantageous in the process as described in British patent application 19304/71 is described.

Or. Müller-Bore Dr. Manltz Dr. Deufel ■ Dipl.-Ing. Finsterwald Dtpl.-Ing. Grimkov Braunschweig, Am Bürgerpark 8 8 Munich 22, Robert-Koch-StraB «1 7 Stuttgart-Bad Cannstatt, MvktstraBe

Although mills of this type provide a very efficient comminution of particulate materials and

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Difficulties encountered when crushing very hard materials such as fly ash. Ss was found that the inner surfaces of the mill chamber then into one be abraded to such an extent that the resulting wear on the surfaces and the presence of impurities in the comminuted products makes the use of such mills uneconomical. So far are such mills have always been set up so that the axis of the cylindrical chamber was vertical, and the wear and tear then shows itself mainly on the flat circular bottom plate of the mill.

According to the invention, a mill is provided with this ϊτρβ a cylindrical chamber, the axis of which is arranged horizontally, which is lined with flat side plates, which are divided into a plurality of segments, and which has curved peripheral sides selected from a plurality consist of abutting plates, the segments and plates being separately removable and replaceable.

This arrangement surprisingly shows the effect that the wear is localized in the lower parts of the mill '' will. It was further found that the gas or Gaa pressure surges from the UnfnTigutisen eia Zueanaeat meet between the 3 wall and 4 particle-free material on one Reduce the minimum and «with the wear and tear even on the lower circumference»

While earlier the entire · Bedenplatt · of the mill was worn out Has been, with the furniture according to the invention, there is wear and tear on the lower one or two segments of each side

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plate and the adjacent flattening of the circumferential sides. This wear and tear can easily be fcaütiOXliesrb w # y4 «B _; £ m & * m "sfcwed"? The mill is rotated, distributing the wear evenly over all surfaces, or the individual plates and / or segments, when they are worn, replaced.

Eib is of advantage in constructing a HQhIe for the comminution of very abrasive or abrasive particulate materials was very well known To be able to use hard materials such as silicon carbide, tungsten carbide, boron carbide and hot-pressed Alnainiuaoxide. Many of these materials are used as abrasives as such. Unfortunately, their hardness and earth strength is inherent in them b £ $ »Fragility such that it is very difficult and are very laborious to edit. ■ only in a limited way Anasbl of forms of how flat plates are made can. As a result, it is not economically feasible in known comminuting mills to do the same To use materials for the inner surfaces of the mills, since ring-shaped ropes are not economical can be manufactured in the dimensions required for the curved Bafangsoberfläohe of the mill or the cylindrical Eye at the center containing the outlet.

As far as the circumferential and lateral vaults of the mill are concerned, the invention enables such materials to be used. The Segmeaten Seltea plates are flat and do not pose a problem and the circumferential walls of the mill consist of a great number be built up of small flat plates made of abrasion-resistant material.

The best results are obtained by using a large anal of small flat uBf * ap-S »it # apIattea,

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in order to provide a circular chamber as precisely as possible and ensure that the flat plates are in reasonable

or be supported. As a result, each peripheral forms side plate preferably an angle of not more than 5 °, preferably not more than 2 (1/2 ° with the axis of the mill.

A preferred feature of the invention enables such materials also for the central eye of the mill, which forms the outlet to use. According to the invention, the eye consists of a large number of tangential wings or blades, which are arranged in a circle around the axis of the mill parallel to the axis of the chamber and inclined to its radii are.

using these features it is possible in more economical Way to build a mill according to the invention,

chamber
whose / insubstantial is completely lined with an abrasion-resistant material. This material preferably has a Knoop hardness value of more than 2100 (Knoop 100GM). The plates made of this material, of which the lining of the mill chamber is made, can easily be removed and replaced if so desired.

Examples of suitable materials are given below.

While using tangential blades on the eye the mill is primarily preferred because it enables the use of abrasion-resistant materials, she points out also advantages in relation to the suffering behavior of the Mill yourself on “The use of such sheep provides a way of getting a finer particle size with a to obtain a narrower size distribution of the products than with

the mills with the well-known cylindrical eye; in order to obtain these characteristics, it is only necessary to adjust the size of the tangential wings or blades in a corresponding manner. Around to obtain a significant increase or improvement in the classification of the product, the Paddles extend outwardly at least a distance of R / 3 from the axis of the mill (where R is the inner radius the Mühlenkamiser is).

Another preferred feature of the invention is that a device is provided for the separation of the crushed particles leaving the mill by the gas in which they are entrained, so that the gas either recycled or released into the atmosphere. This can of course be done in a known manner using an electrostatic precipitator or a cyclone group. However, the results will be better sometimes obtained using a bag filter, one known design of which is 99.9998 efficient for the separation of particles with a size of 1 u

A device is preferably provided for the direct injection of a coolant, for example water, into the mill outlet in order to reduce its temperature to a value at which the outlet can be processed by the downstream system.

For example, the mill according to the invention can be used for fine comminution or comminution to micron size (micronization) of pulverized fuel ash with steam about 15 atmospheres (220 psig) superheated to about 350 ° C, be used as a dragging gas; the mill exit is located

then at about 280 ° 0.

Vertically arranged mills are known, for example, from US Pat. Nos. 3,229,918, 3,058,673 and 2,628,786 and GBi-FS 1 098546, 1 222257 and 660674. Cool with interchangeable linings of various great and materials are from the US Patent No. 3,229,918 and 2,690 88O ₁ of the publication "Mining Engineering", 4 March 1952 pages 262 and following GB = 1 HB 137320, 1 22225? mnd 636503 known. However, no cylindrical mills with segmented flat side liner plates are known to date. Mills with a variety of flattening are known, for example, from US Pat. No. 2,690,880, but the plates shown there are not flat and have been introduced as filling units to prevent gelatinization or clogging of the mill and not to prevent wear. Finally, cylindrical mills with a ring of tangentially arranged openings around the outlet are known from GB-PS 11Θ308, 639 762 and 636503, but tangential, classifying blades in a cylindrical mill are not known as such. GB-PS 1 222257 describes a horizontal mill with a "spider" in the outlet, but this is not equivalent to the tangential classifying blades according to the invention and does not achieve the same results.

The invention is illustrated below with reference to the drawing, for example:

Fig. 1 is a general elevation view of one according to the invention

Mill, FIG. 2 is a general plan view of that shown in FIG

Mill, 3 is a horizontal sectional view taken along the mill their horizontal diameter shown in Fig. 1 3-3,

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Pig. 4 a vertical section of the mill along the lines shown in FIG

indicated lines A-A, FIG. 5 shows a vertical section of the height along the lines in FIG. 3

indicated lines B-B, Fig. 6 is a view on an enlarged scale of a part Wg. 5,

7 is a detailed cross-sectional view of a portion of FIG Fig. 3 on an enlarged scale in which is shown. how the tangential «? * blades are attached to the side plate of the mill, and

8 and 9 are schematic flow charts for processes for the fine comminution of pulverized fuel ash Use of the mill according to the invention.

Hr <3h of Figs. 1-5, a mill comprises a flat straight cylindrical body, which encloses a cylindrical chamber, w ^> ei the common axis of the body and d «r Chamber runs horizontally. The body includes a delivery side panel 2 and an access side panel 3 «, the the former has a peripheral annular flange 2 * ^ mfafttV ^ tta this of the access side panel 3 at a distance. A discharge outlet 1 is provided in the center of the discharge side plate 2. Eis BinefeisuBgsinjektor 4 · leads through the delivery side plate 2 into the mill chamber. The two flatten can by any suitable means, such as hinged G-clamps G to each other.

The Sinspeiisungsindektor 4 comprises a funnel 4- ', which leads into a line 4- ", which includes a venturi device 4-" ¹ . High pressure gas is passed along the line 4- ", tearing particulate material from the funnel 4- 'with aaiii MühleaKasme?

j the mill.

In an alternative embodiment not shown, the injector 4 lies in the plane of the mill and does not lead in the side plate 3 but in the curved peripheral wall

It is also possible to vary the design shown by replacing the venturi feeder 4 * ¹ *, 4 * ¹ * 'with a simple mechanical feeder such as a screw feeder located in the injector 4-.

Between the side plates 2 and 3 and concentric to them there is a jet ring or nozzle ring 13, which is regularly spaced, copolymeric, angled, Bores 14 containing nozzles. The ring flange 2 *, the nozzle ring 13 and the access side plate 3 enclose an annular space 7 which serves as a gas chamber. One Line 16 is provided for the supply of high pressure gas to the gas chamber 7.

The discharge and access side panels 2 and 3 and the inner Surface of the nozzle ring 13 define a cylindrical mill chamber 15, which according to the invention with an abrasion-resistant Material shown in black is lined. The side plates 2 and 3 each have 4 segment plates 8 lined with this material and the surface of the nozzle ring 13 is protected by a large number of flat rectangular plates 10 made of wear-resistant material (which is shown in more detail in Jig. 6) · These plates are drilled where necessary, around the To allow access of high pressure gas through the nozzles 14 from the gas chamber 7 to the mill chamber 15.

In the center or eye of the mill there is a ring with tangential blades or blades 11, which are flat

if made of the abrasion-resistant material. These blades are parallel to the axis of the mill and equidistant located from this but in the opposite direction to a diameter of the mill; to the angle of the Gaöeinläsae 16 angled.

In operation, the gas chamber 7 with high pressure gas, usually Air or steam fed into the chamber 15 through the nozzles 14 to create a helical flow of gas cause inside the mill chamber 15. The gas exits through outlet 1. Particulate to be warned Material is introduced into the mill chamber through feed 4, also entrained in high pressure gas, where the size reduction or downsizing takes place.

In Fig. 6 is more detailed, a Braeh section (scrap section) of Düsssring 13, a nozzle 14 «nd Ρ1« 1? ΐ? β !!> 10 of the abrasion-resistant material shown. According to Fig. 6, the inlet hole is through the nozzle ring 13 and a plate with drilled at an angle to the radius of the mill and lined with a nozzle 14, which is preferably made of wear-resistant material consists, but does not necessarily have to consist of the same material as the plates 10. The nozzle 14 may be a have a cylindrical bore or diverge towards the mill chamber; the latter configuration has the advantage that upper sound velocities can be achieved for the introduction of gas are.

In Fig. 7 it is shown in detail how the tangential Blades 15 on. the access side panel 3 by means of a Blade clamping plate 12 are attached.

The abrasion resistant materials from which the segment side panels 8 and panels 10 are made can be any comprise an abrasion-resistant material that has a Knoop hardness greater than 2100 (Knoop 100 GM). The chosen lining

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dung material depends oa. on the ability to grind (abrasive nature) of the supplied material and the gas in which the purbikelföraiie · material mitgvjc-iaead qcird «ab · Si« Files made from this material are removable and interchangeable.

If air is used as the entrainment fluid in the mill, preference is given to high density hot pressed boron carbide, typically at the density of 2.52 grams per square meter, for the abrasion resistant surfaces; this density is more than 99 % of the theoretical value · This material has a Knoop hardness of 2800 (Enoop 100 GM). Bs is available from Carborundum Ltd. under the trade name "HD Boron Carbide".

When steam is used as the gas in which the grinding materials are entrained, the bevox ¹ -drawn lining material is self-bonded reaction-sintered silicon carbide, typically with a density of 3.10 g per cm. This is 97 % of the theoretical density. This material has a Knoop hardness of 2740 (Knoop 100 GM). It is available under the trade name ^ EP Silicon Carbide ^) from Carborundum Ltd. available.'

Whichever material is used inside, the density should be as close as possible to the theoretical value xm to obtain the maximum wear resistance.

The boron carbide described above is preferably used, but this material is attacked by steam • s required, the silicon carbide material described above to use in the presence of steam. The silicon carbide material can, however, also be used in air.

Other lining materials that can be used are tungsten kirbid, which has a Knocp hardness of 17ΟΟ (Knoop 100 GM), and hot-pressed aluminum oxide, the has a Knop hardness of 2050 (Knoop 100 GM). However

XBb xux * uou xu UOX- u'igiBuueu fauouveuuuaxuuuc λ. ·? y \ t-rg ξ λ. a material with an Enoop hardness of 2100 (Knoop 100 GM) is preferred.

The nozzles 4 should also be made of an abrasion-resistant material, but it is not necessary that they are as abrasion-resistant as other parts of the mill lining. For example, even in the process described in the patent application ITr.19304 / 71, it is possible to use nozzles 14 made of tungsten carbide or hot-pressed aluminum oxide.

In Figures 8 and 9 are flow charts of plants that would contain the mill, for reducing to micron size (micronizatioD.) Of pulverized fuel axis, as described in the British Patent Office -. * ^ Ing .19304 / 71 is shown. The HFthle 20 is fed with high pressure gas through a line 21 and from a funnel 22 with feed material entrained in the gas. The outlet 23 of the mill leads to a line 24. A coolant such as water at 15 ° G can be injected at 25 if necessary. The line 24 leads into a container 1 »between. Funnel 26 containing a bag filter which may be of any suitable type. Ufer sack can, for example, consist of a nylon fiber material that is resistant to temperatures of 250 ^Θ 0 and does not melt or drip. The gas is discharged along a line 27 and the solid phase is removed from the container or funnel 26 for further processing or for packaging. The exhaust gas leaving line 27 can be reintroduced into the cycle when recirculation is economically desirable. Especially when

i - 12 - the Γ ··· can simply put the exhaust gas in usual- earth. Hochdi ^ jickdajwDf vii * d I compressed air is used, * AinnosphMre blown off ν
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wisely condensed and re-evaporated for recirculation at 21 and other gases such as nitrogen and argon are usually recompressed before being recirculated at 21.

In Pig. 9 shows an alternative scheme in which a cyclone group 28 produces the main separation. That Injection of a coolant is generally not required in this embodiment and the bag filter and the container 25 can be omitted, although they are shown, as they are advantageous for removing the know the last traces of solid material used by the effluent.

Claims (1)

Schutsaη sayings 1. Mill for fine comminution by mutual attrition τοη particulate entrained in a gas Gen material, characterized in that a cylindrical "Ea" M "3? (15> with its Aeha" is arranged horizontally, is clad with flat side plates {8) which are divided into a multiplicity of segments, and curved circumferential sidewords includes, which comprise a plurality of abutting plates (10), and that the segments (8) and the plates (10) are separately removable and replaceable. 2. Mill nae-i claim 1, characterized by an axially arranged outlet opening (1) in a side plate (2) and through a plurality of fcaagentialea Paddles (11) located in a circle around the axis of the mill parallel to the axis of the chamber (15) and to the latter Radii are inclined. 3. Mill according to spoke 1 or 2, characterized in that the segments (8) and the side plates (10) and the tangential blades (11), if they are intended to be made of a material with a Khoop hardness value greater than 2100 (Knoop 100 GM). 4. Mill according to claim 3 «characterized in that the material is hot-pressed high boron carbide? Density is. Il I ι »· ι »ι t> - G 73 OO II 3.5 - 14 - 5 · Mill according to claim 3 »characterized by · - · net that the material is self-glued, reaction-sintered Is silicon carbide. 6. Mill according to one of the preceding claims, characterized in that the abutting Plates (10) in the Umfants side walls are flat and rectangular and that each have an angle rcXt from the central axis the chamber voa does not include more than 5 °. 7 · Tables according to one of the preceding claims, characterized characterized in that they are dimensioned suitable for crushing pulverized fuel ash and liner.