FI121369B - Improved accelerator nozzle for gas-solid suspension - Google Patents

Description

Improved accelerator nozzle for gas-solid suspension -Förbättrat accelerationsmunstycke för en gas-fastsubstance suspension 5

The present invention relates to an improved accelerator nozzle for a gas-solid suspension #

In order to accelerate the gas-solid suspension, a tubular nozzle with a uniform internal diameter or, for the highest speeds, slightly tapering on the inlet side and slightly expanding on the discharge side is usually used.

In order to obtain sufficient speed, for example, to grind the solid particles, the gas-solid suspension must have a relatively low solids content. As a result, a relatively large amount of gas enters the refining chamber, which partially interferes with the actual refining process. In principle, the milling process does not require working gas. Some of the working gas may be removed after the particles have reached their optimum speed at the nozzle. Thus, it would be desirable to find a means for diverting excess gas 20 prior to the milling zone.

This objective is achieved by the accelerator nozzle according to the present invention.

• * * I

· ... * *, characterized in that a plurality of middle passages of the flow channel are made on the wall of the tip • • •. '* I are gaseous discharge channels extending obliquely outward from the direction of the rib A through which a fluid is arranged to discharge from the flow.

* '*: *' 'This solution allows the coarse grinding masses, which are larger in mass, typically moving around the center axis of the nozzle, to keep the solids from turning to the gaseous discharge channels and to continue' '* *: 30 movements in accordance with the law of continuity of motion, with only a slight loss of kinetic energy generated in the • · i. * ·· nozzle. In the case that the tip portion is • · ·. **: the remainder of the tapered tapered gas discharge passages are located at the beginning of said 2 tapering, where the gas-solid suspension rate is high. Hereby, the particle number and kinetic energy per unit area continue to increase due to the tapering of the tip, while a portion of the gas used to initially accelerate the gas-solid suspension is exited from the nozzle through said gas discharge channels. Even the smallest solid particles in the suspension, which do not require additional grinding, are removed through these gas release channels.

Preferably, said gas release channels are spaced evenly adjacent to each other in an annular order to form at least one circumference. If the cross-sectional area of the individual gas release channels 10 is to be kept small, these channels may be arranged in a plurality of circumferences. The best effect is obtained when the suspension enters the gas passage without causing disturbing turbulence to the upstream end of the gas passage. This is achieved if the gas discharge passage forms an angle of about 45 ° with the central axis of the flow passage.

15

According to the invention, the gas discharge ducts may be, for example, rectangular or circular in cross-section, uniform in size or expandable in the downstream direction, or conical or cylindrical and in some cases may be in the form of a longitudinally extending end.

• · · • · • * • • • • • · · · · · · ·. Since the most abrasive part of the accelerator nozzle is its tip portion, this is a releasably mounted accelerator in accordance with a highly preferred embodiment of the invention. · * *. to the nozzle outlet. Thus, tapering of the flow passage of the tip portion, and at the same time the first ends of the gas discharge passages are preferably located in the middle region of the tip portion. The flow passage at the end of the tip portion preferably tapers such that its reduction in cross-sectional area at least corresponds to at least about 20% of the cross-sectional area of the upstream end of the flow section. Length of the tapered portion of the tip portion at the gas outlet inlet • · ·. ♦ ··. At the 30-point outlet end, the composition and material to be milled • • ···. : based on features. If the material to be milled is very light and finely divided, the length of the taper section must be very short, and the coarse and heavier quality of the material to be milled may be relatively long.

Accelerator nozzles of the above type may advantageously be mounted in a refining refiner refining chamber such that two such accelerating nozzles are mounted on opposite sides of the refiner chamber, extending into the refiner chamber and oriented at a common location in the center of the refiner chamber. The center axes of the accelerator nozzles preferably intersect at an angle of slightly less than 180 °.

In such a counter-jet refiner, the high-velocity coarse solid particles fly linearly at the collision point of the two gas-solid jets where they collide with the solids from the opposite accelerator nozzle and grind. Some of the working gas exits the accelerator nozzles through said gas discharge channels so directed that they do not cause interfering gas streams in the refining zone itself. Thanks to the gas discharge channels, the tips of the opposing accelerator nozzles can be brought very close to each other without significant increase in back pressure. Due to these gas release channels, the area where the fins collide will get less air, which also contributes to slowing the exit of the particles from the collision area and to the particles staying longer. in the effective milling zone.

• · «· • · ... 20 According to a preferred embodiment, both accelerator nozzles are removed. a thick spacer is provided between the ends, having a through opening of size · · ·· ·: the size of a through hole of the accelerator nozzle intersecting the center axes of these accelerator nozzles; at the point. In this case, a limited ··· 25 milling zone is formed in said through-hole because the sides of the baffle effectively deflect the gas streams flowing from the gas-discharge ducts from that milling zone. The best result is achieved if the baffle is shaped such that each side surface forms a straight line. angle with the center axis of the accelerator nozzle towards it.

• · ·· * • · • · • · t ···. 30 The refiner housing of the counter-jet refiner is preferably of cylindrical cross-section • ·

«I •

shaped with one or both ends having powder gas-solid suspension outlets and acceleration nozzles extending through the cylinder casing.

4

According to another preferred embodiment, the cylindrical refiner chamber of the counter-jet refiner has a cylindrical baffle centrally disposed through which the tip portions of the accelerator nozzles extend so that the gas discharge passages therein terminate outside the cylindrical baffle. This ensures that all the gas that leaves the gas discharge channels and carries with it the fines that do not need to be milled are already separated from the millable solid stream before milling, whereby milling takes place in a state free of annoying external gas streams. Preferably, the gas-fines mixture exiting through the degassing ducts 10 is completely separated from the refiner chamber and recovered, while the material milled inside the septum is conducted in a separate stream from the refiner chamber. As a result, the cylindrical partition is closed at one end. Thus, a preliminary classification of the material gas stream is performed at the same time.

15

According to a preferred embodiment, the proportion of the gas solids discharged through the gas discharge passages is adjustable by adjusting the pressure in the space outside the partition of the refining chamber. This feature can also be utilized when the equipment is mainly used as a classifier, in which its grinding • • · · ... function is neglected or completely abandoned.

1 / In the following, the invention will be described in more detail with reference to the accompanying drawings, with reference to which, where: FIG. 1 illustrates, by way of example, a detailed side view of an embodiment of the tip portion of an accelerator nozzle according to the invention, partially cut away;

Figure 2 shows a first example of a counter jet refiner • ·: * * ': as seen from the liner section in the direction of the center axis of the refiner chamber, and cut along • · ·. ···. 30 Accelerator Nozzle Center Shafts, • 5 · 5 *

Fig. 3 shows an alternative embodiment of a refining section of a counter-jet refiner, viewed from the side and cut away along the central axes of the accelerator nozzles; and Fig. 4

As shown in Figure 1, the acceleration nozzle 1 according to the invention consists of a conventional nozzle 1 with an outlet end having a tubular tip portion 2 having a flow conduit 3 at least remainder tapered in the flow direction and a plurality of The gas-discharge channels 4 extending obliquely outward from the A direction are preferably disposed equally spaced in a circular order so that excess gas is discharged from the nozzle 1, 2 evenly at approximately the same position in the longitudinal direction of the nozzle.

Preferably, each gas discharge passage 4 forms an angle of about 45 ° with the central flow axis A of the flow passage. The gas-discharge passage 4 may be circular in cross-section or 20 rectangular in shape, and may be of equal or expandable cross-section as shown in Figure 1.

The tubular tip portion 2 of the accelerator nozzle 1 is preferably removably secured to the outlet end of the conventional accelerator nozzle 1 so that it can be easily replaced after completion. In this case, the gas discharge passages 4 are preferably located in the middle region of this tip part 2. The attachment of the tip portion 2 to the end of the accelerator nozzle 1 is · · · suitably accomplished by means of a special mounting sleeve 9.

The refining chamber 5 of the counter-jet refiner shown in Fig. 2 has a cross-sectional area ···. ···. 30 cylindrical, with two acceleration nozzles 1 with tip 2 extending opposite • · • · · | from the axial sides, substantially radially through the cylindrical • surface of the refiner chamber 5 so that they are directed to a common point B in the center portion of the refiner chamber 5, where the center axes A of the accelerating nozzles intersect at an angle of 180 °. The gas discharge openings 4 of the tip portions 2 end up in the refiner chamber 5, close to its casing surface, so that any excess gasses is discharged along the casing surfaces of the refiner chamber 5 to the outlets 8 at both ends without interfering with refining in the center.

According to a preferred embodiment of the invention, the refiner chamber 5 is fitted with a thick spacer 6 between the outlet ends of both accelerator nozzles 1,2 and at an interval of 10 from each, so that the refiner chamber 5 is partially divided into two compartments. In front of the accelerator nozzles 1, 2, the baffle plate 6 is provided with a through hole 7 of substantially outer circumference of the accelerator nozzles 1,2, which forms a refining zone protected from interfering gas streams. Namely, a considerable amount of gas coming from the outlet of each accelerator nozzle 1,2 is exited from the gap between the tip part 2 of each accelerator nozzle 1 and the baffle 6, which width is preferably adjustable according to the material to be milled by changing the distance between the tip portions 2. As a result, the spacer plate 6 is preferably shaped such that each side surface forms a right angle to the central axis A of the accelerator nozzle 1,2 directed towards it. In the embodiment of Fig. 2, said spacer 6 protrudes from the shell wall of the refiner chamber 5 on the side which is. farther away from the passages of said accelerator nozzles 1.

• · · • • · *. In contrast, the counter-jet refiner of Fig. 3 has only one powdered gas • ·: ***: removal of the solid suspension 8, whereby the other end of the cylindrical refiner chamber 5 is · · 25 closed by a thick metal plate 10. In this embodiment, / * · The baffle 6 extends from the end of the closing metal plate 10. Since the outlet of the refiner chamber 5 · · · * ... · 8 is only at one end, the acceleration nozzles 1 are slightly inclined · * · *: the outlet 8 extends a corresponding extent · »« removal 8. The milled knntoainesupensio gas exits the arrow C direction. · **. The cylindrical refiner part 5 of the counter-jet refiner of FIG. the gas discharge ducts 4 terminate outside this septum 6a so that the gas-fines-5 suspension exiting the accelerator nozzles 1,2 through the degassing ducts 4 enters a space outside the septum 6a of the refiner chamber 5, which can be removed separately from the flow 7a to present the direction of the arrow C for further processing. Thus, in this grinding chamber, a preliminary classification takes place. By controlling the pressure 10 in the refining chamber 5, outside the septum 6a, it is possible to control the proportion of the gas-fine mixture exiting the accelerator nozzles 1,2 through the degassing channels 4 through the total amount of gas-solid suspension fed through the accelerator nozzles 1,2.

It is to be understood that the drawings are intended only to illustrate the inventive idea and not to limit the invention. It is obvious to a person skilled in the art that the details of the subject matter of the invention may be altered within the scope of the appended claims.

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Claims (8)

8 P 8 h Claims: i An improved accelerator nozzle for a gas-solid suspension, wherein at the outlet end of a conventional accelerator nozzle (1) is provided a tubular interior of a toothless tip portion (2) having a flow channel (3) of substantially the same size or at least gas discharge passages (4) extending obliquely outwardly from the direction of the central axis (A) of the flow channel (3) through which the flow medium is arranged to discharge off the flow. Acceleration nozzle according to Claim 1, characterized in that the gas discharge ducts (4) are spaced evenly next to each other in an annular order, preferably at the beginning of the tapering of the flow channel. An accelerator nozzle according to claim 2, characterized in that each gas-15 discharge conduit (4) forms an angle of about 45 ° with the central axis (A) of the flow conduit (3). The accelerator nozzle according to claim 3, characterized in that the gas discharge • • t! The working channels (4) are rectangular or circular in cross-section and through,! ; 20 of the same size or expanding downstream. > <<t I Accelerator nozzle according to Claim 3, characterized in that the gas passages (4) are formed by longitudinal slits extending to the outlet end of the tip part (2). Accelerator nozzle according to one of the preceding claims, characterized in that said tubular tip part (2) is removably attached to the outlet end of a conventional accelerator nozzle (1). <*. K Acceleration nozzle according to Claim 6, characterized in that the gas discharge passages (4) are located in the middle region of the tip part (2). • '* 1 Λ /'. * Acceleration nozzle according to Claim 1, characterized in that the flow passage in the remainder of the tip portion (2) tapers so that its reduction in cross-sectional area corresponds at least to the total cross-sectional area of the inlets of gas discharge channels (4) naked .. 5 10 15 20 25 30