EP1080786A1 - Method, device and system for fluidised-bed jet mill - Google Patents

Abstract

The pulverizing process involves breaking down particles in a fluidized bed by means of a fluid jet (6, 7). The application of centrifugal force to the particles in the region of the fluid jet or jets causes more energy to be used on the particles in the fluidized bed, particularly in the vicinity of the fluid jet entrance.

Description

In the case of fluidized bed grinding, there is a flow in a fluidized bed from a fluid and solid particles suspended in the fluid generated in such a way that the solid particles by energy exchange be crushed. Part of the flow with solid particles below a certain mass or a certain Weight is branched off in a classifier and the further processing e.g. fed in a filter while Solid particles above the aforementioned limit in the Residual flow remain and the fluidized bed grinding again so long be fed until their mass or weight below of the limit.

In the case of fluidized bed jet grinding, the flow in the fluidized bed favored by fluid jets that enter the Fluid bed are introduced and the solid particles in the Induce fluid bed to increased energy exchange. This effect is particularly well achieved, though the high energy fluid jets a suspension of fluid and Solid particles are removed from the file bed if necessary have experienced an energy increase and then with their increased energy can be returned to the fluidized bed.

In order to be able to implement this principle particularly well in practice, Several measures have already been proposed.

One of these suggestions is based on the knowledge that the high-energy gas jets when entering the fluid bed Pick up solid particles from the fluidized bed and thus also inside the energy-rich fluid jets a particle decomposition takes place, this particle separation then particularly takes effect when influence on the particle distribution in high energy gas jet is taken in that the Particles distributed as evenly as possible over the beam cross section are.

In all of these solutions, the fact was not consciously taken into account borne that the energy-rich fluid jets upon entry into the fluidized bed not just an energy exchange between Solid particles of the fluid bed and / or the energy-rich Fluid jets cause but this energy exchange only from a certain distance from penetration The high energy rays in the fluidized bed starts because the energy-rich fluid jets first of all as relatively laminar Flows at least the solid particles into the fluid bed oust it before a turbulence takes place that leads to the willful energy exchange leads.

The present invention is concerned with this Phenomenon by showing ways of how the high-energy Fluid jets into the fluidized bed with high energy can be introduced while preventing the solid particles to be dismantled initially without any noteworthy Energy exchange is pushed into the fluidized bed; in other words, it is said to be the fluidized bed solid particles despite the high-energy fluid jets introduced into the fluidized bed in the area of the entry of high-energy fluid jets be held in the fluidized bed so that the energy exchange between solid particles in the fluidized bed already very intensive in the immediate area of entry the high-energy fluid jets into the fluidized bed.

The essence of the invention for solving this problem is, on the one hand, that on the solid particles in the area of penetration of the Fluid jets of high energy into the fluidized bed, centrifugal forces like this be brought to effect that energy exchange between the solid particles that are part of the high energy Fluid jets are created immediately after penetration the high energy rays into the fluidized bed begins and on the other hand generally the concentration of the solid particles is improved within the fluid jets.

Fig. 1

als Mittellängsschnitt eine als solche bekannte Fließbettstrahlmühle in einer Ausbildung gemäß der Erfindung;

Fig. 2

ebenfalls als Mittellängsschnitt eine bereits von Anfang an erfindungsgemäß ausgebildete Fließbettstrahlmühle ;

Fign.3 bis 5

jeweils als Mittellängsschnitte andere bereits von Anfang an erfindungsgemäß ausgebildete Fließbettstrahlmühlen und

Fig. 6 mit den Teilfiguren 6a und 6b

Diagramme zur Erläuterung der Funktionsweise der Erfindung in einer Ausführungsform, wie sie in den einen Hälften von Fig. 4 und Fig. 5 dargestellt ist.

The invention is explained in more detail below with reference to the drawing, in which, however, only examples are shown which do not represent a restriction of the essential features of the invention as result from the patent claims. The drawing shows:

Fig. 1

as a central longitudinal section, a fluid bed jet mill known as such in an embodiment according to the invention;

Fig. 2

also as a central longitudinal section, a fluidized bed jet mill designed according to the invention from the start;

Figures 3 to 5

in each case as central longitudinal cuts, other fluid bed jet mills designed according to the invention from the start and

Fig. 6 with the sub-figures 6a and 6b

Diagrams for explaining the operation of the invention in an embodiment as shown in one half of FIGS. 4 and 5.

1 shows a fluidized bed jet mill operated with superheated steam as it is known per se. A cylindrical case 1 encloses a chamber 2, which in the lower area Fluid bed 3 takes up and is the actual grinding chamber. This Fluid bed 3 consists of solid particles in a fluid, which are more or less evenly distributed in are suspended in the fluid. They have different masses and should be ground evenly to the finest particles. For this purpose, two diametrically opposite one another Jet nozzles 4, 5 high-energy fluid jets 6, 7 blown in, which penetrate the fluidized bed 3 in such a way and that solid particles collide and through energy exchange be disassembled. The particles remain in the fluidized bed for so long and especially in the area of high energy in the fluidized bed entering fluid jets 6, 7 until their mass has become so low is that it is from the upward beam 8 - the sum of the clashing and doing the energy exchange energetic between solid particles individual jets 6, 7 entering the fluidized bed 3 are entrained be, while the not yet finely ground Solid particles in the area of the individual jets, i.e. in the actual fluid bed 3 remain and through energy exchange be further disassembled. In the upper area of chamber 2 or Housing 1 is now a fines outlet chamber 9 which in turn is the fines outlet nozzle led out of the housing 1 10 joins. That through the outlet nozzle fine material made from the finest particles leaving the mill suspended in one part of the fluid, the other Processing, for example fed in a filter in which Particles and fluid are separated.

The regrind passes through a regrind inlet connection 11 in Cover the housing in the grinder. At 12 is a steam supply for the gap rinsing between the stationary in the housing 1 arranged fine material outlet chamber 9 and one above rotatably arranged classifying wheel 13. The classifying wheel 13 takes advantage of the in it, if necessary between the blades of a bladed sight wheel, prevailing Centrifugal force that only finely ground material in the outlet nozzle 10 arrives while not quite as finely ground Well rejected and using gravity like that original regrind gets into the fluidized bed 3 and continues there is disassembled. The drive 14 of the classifying wheel is outside of the housing 1 mounted on the cover and through the housing cover through functionally connected to the sight wheel 13.

In such a fluid bed jet mill known per se now observed that in the area of the jet nozzles 4, 5, which in several pairs with two diametrically opposite one another Individual nozzles for high-energy introduction diametrically juxtaposed jets in the fluidized bed can be solid particles in a rather laminar Initial flow are carried away until a certain distance from the nozzles the swirling and an effective Energy exchange takes place between the particles. this will felt as a disadvantage because the area of the rather laminar Flow as a grinding area is lost as it were. This should now can be avoided with the invention and entrainment of the particles in front of the nozzle outlets with no energy exchange between they should be hindered or in other words the solid particles despite the high energy in the fluidized bed entering fluid jets in the area of the nozzle outlets and immediately after the energy-intensive fluid jets begin the milling process, with a certain turbulence already in the nozzle area would not only be acceptable, but even desirable because yes thereby the exchange of energy between the particles if not even triggered, so at least is favored and that Blasting in particular immediately after exiting the nozzles are high in energy.

The described, desired effect is now according to the invention applied in that the particles on the one hand the radial flow energy directed inward into the grinding chamber, such as described, exposed, but also one opposing centrifugal force, with centripetal forces on the one hand (nozzle outlet jets) and centrifugal forces (centrifugal force) be coordinated so that they are immediately the degree of optimal particle separation in the nozzle area is present. As can be easily understood, can this situation along with a number of functional advantages structural advantage that the mill has a lower Diameter than the stationary mill shown, because the grinding area starts closer to the wall or the diameter can be maintained and efficient grinding takes place in a larger diameter range.

With this level of knowledge, the invention can now Fluidized bed jet mill according to FIG. 1 can be implemented, that while maintaining the rotation of the sight wheel opposite the mill housing 1, the mill in its entirety for turning is brought about its longitudinal axis. The mill housing 1 is on its upper and lower ends in suitable bearings 15, 16 and the mill housing 1 is a rotary drive 17th assigned so that the mill is driven by such a drive Speed or peripheral speed set in rotation the arrows 18 marked, counteracting the inward beam forces Centrifugal force and the transfugal and the transpedal energies are balanced against each other, that an energy exchange between solid particles of the Fluid bed and optionally the energy rays 6, 7 also in the areas immediately before the grinding nozzles.

To the raw product through the inlet port 11 and the high energy Fluid jets 6, 7 and any other high-energy Fluid jets for penetration into the fluidized bed 3 in the mill introduce and the finely ground regrind through the outlet nozzle To be able to get 10 out of the mill, Stub 4, 5 and 11 annular chambers must be upstream and must Stub 10 an annular chamber downstream, in each If part of the chamber wall of the mill is assigned to rotate and another part of the chamber wall must be stationary, wherein both chamber wall parts are sealed against each other.

While the mill according to FIG. 1 is a known, originally fixed fluid bed jet mill, which was redesigned according to the invention by the housing 1 is made to rotate about its longitudinal axis 1a, is Fluid bed jet mill according to FIG. 2 from the outset according to the invention educated.

An essential part is a rotor 2.1 made of an inner housing 2.2 and an outer housing 2.3. Inner housing 2.2 and outer housing 2.3 are rotatably connected to each other, what by Welding beads 2.4 is indicated. They are so assigned to one another essentially cylindrical parts that between them a fluid-tight annular chamber 2.5 is formed and that Inner housing 2.2 encloses a grinding chamber 2.6. An approximately frustoconical Cover plate 2.7 of the inner housing 2.2 is from passes through a regrind inlet pipe 2.8, so that through the regrind inlet pipe 2.8 the suspension of carrier fluid and therein suspended solid particles enter the grinding chamber 2.6, in which the solid particles are subjected to the grinding process become. A second cover plate 2.9 is the first cover plate 2.7 opposite and is penetrated by a fine material outlet pipe 2.10, so through the fine material outlet pipe 2.10 the suspension Carrier fluid and suspended therein to the desired low Mass of ground solid particles, that is, on one Desired fineness of ground product from the grinding chamber 2.6 are removed and sent for further processing can. The cover plates 2.7 and 2.9 are inclined towards each other that they are on their larger, same sizes with the cylindrical peripheral wall 2.11 of the inner housing 2.2 connected are and assigned to each other so that regrind inlet pipe 2.8 and fine material outlet pipe 2.10 assigned to each other with the same axis are. In front of the regrind inlet pipe 2.8 and the fines outlet pipe 2.10 a traffic cone 2.12 or 2.13 is arranged, of which the traffic cone 2.12 assigned to the inlet pipe 2.8 into the Grinding chamber 2.6 entering regrind in the area of the cylindrical Circumferential wall 2.11 brings or this flow course supported, while that assigned to the fine material outlet pipe 2.10 Traffic cone 2.13 from the edge of the fine material outlet pipe 2.10 expanded in a funnel shape that together with the Traffic cone 2.12 a well-defined grinding chamber core area defined between inlet pipe 2.8 and outlet pipe 2.10. In the cylindrical peripheral wall 2.11 are now at least two jet nozzles 2.14 and 2.15 opposed to each other in pairs like this held that through them grinding jets 2.16 and 2.17 into the during operation of the device, particularly in the core area the fluidized bed of the milling chamber 2.6 is energetic penetration. The grinding jets 2.16 and 2.17 swirl the suspension in the fluidized bed, solid particles collide and are broken down by energy exchange, with which the Fluid bed jet grinding is given.

The grinding jets 2.16 and 2.17 are formed by Fluid conveyed through the jet nozzles 2.14 and 2.15, after it has been removed from the annular chamber 2.5. The feed of the high-energy fluid into the down to the jet nozzles 2.14 and 2.15 closed annulus 2.5 is from a pressurized fluid source out through a concentrically the regrind inlet pipe 2.8 surrounding inlet port 2.18.

The entire system described is now in camps 2.19 and 2.20 rotatably mounted about the axis of symmetry 2.21, so that During the operation of the system, the blowing directions of the grinding jets 2.16 and 2.17 opposing centrifugal force trains. The drive of the system is not essential to the invention and therefore not shown as known. Is essential a relation between the energy of the grinding jets 2.16 and 2.17 on the one hand and centrifugal force 2.22 on the other hand such that the particles to be crushed are as close as possible the jet nozzles 2.14 and 2.15 are kept to in the grinding chamber and to achieve such a small mass as a whole, that they start from the grinding jets in the area the fine material outlet pipe 2.10 promoted and by a suitable Suction device (not shown as usual and known) be sucked out through the fine material outlet pipe 2.10.

3 shows a variant of the device according to FIG. 2, which differs from the embodiment according to FIG. 2 distinguishes that instead of storage on both sides of the mill the bearings in bearings 2.19 and 2.20 are overhung, by the supports 3.18 (in Fig.2 supports 2.18) in the two axially offset bearings 3.19 and 3.20 rotatable is stored.

At the side of the mill and the two bearings 3.19 and 3.20 a drive 3.23 on the inlet port 3.18. Between the two Bearings 3.19, 3.20, a feed device 3.24 is arranged by means of the pressure fluid in the annular space between the inlet nozzle 3.18 and regrind inlet pipe 3.8 arrives and from this into the ring chamber 3.5. Otherwise, the mill of FIG. 3rd corresponding to the mill of FIG. 2 and in both cases Operation essentially the same. The same parts are therefore in both Figures 2 and 3 with the same digits behind the Figure reference 2 and 3 respectively. Due to the flying storage with the two bearings 3.19 and 3.20 there is a larger one Degree of freedom in the use of space on the other Side of the mill. At the free end of the fine material outlet pipe 3.10 is followed by a wind sifter 3.25, which is essential Visible a radial from the outside inwards Blown through sight wheel 3.26 in a housing 3.27. The fine material to be sifted comes in from the mill the housing 3.27 so that it fits into the radially outer ends of the Flow channels between the blades of the classifier wheel 3.26 reached. The relative fines come from the inner ends the vane channels in the centrally located fine material discharge 3.28 to leave the housing 3.27 through it. The relative coarser visible material is at the outer ends of the blade channels rejected and falls down into the funnel-shaped part 3.27a of the housing 3.27, from where it is via a line 3.29 the coarse material to be fed to the mill is mixed and one repeated grinding process is subjected.

4 is similar in the lower Part essentially of the system of FIG. 3, which thereby Expression comes that same reference number behind that on the Figures indicating guide number 3 or 4 used for the same parts are and why on a detailed description is waived.

The wind sifter which is connected downstream in FIG. 3 of the mill 4 as an internal device in the Mill integrated. In the grinding chamber 4.6 is on the inside End of the fine material spout protruding into the grinding chamber 4, 6 4.10 which flowed radially from the outside to the inside, Bladed classifying wheel 4.13 mounted in a rotationally fixed manner. The ground Well gets to the outer ends of the vane channels, and through through them particles below a predetermined mass limit in the fine material outlet nozzle 4.10, around mill and sifter to leave while coarser particles are above this mass limit rejected and subjected to a renewed grinding process become. While both previous solutions of the fines outlet nozzle firmly connected to the mill housing and with this was rotatable, in the solution according to FIG. 4, the fine material outlet nozzle firmly connected to the sight wheel 4.13 and in Bear 4.30 to 4.31 in the assembly from inner housing 4.2 and 4.9 rotatably mounted, so that the sight wheel with the for Sighting optimal speed relative to the assembly from the inner housing 4.2 and outer housing 4.9 can be operated. The The drive acts on the fine material outlet nozzle 4.10 and above it on the classifying wheel 4.123. As for the grinding nozzles, see above the embodiment is the same as below the center line 4.21 Embodiments described so far.

In the embodiment above the center line 4.21 The grinding nozzles 4.14 and 4.15 are installed in such a way that the high-energy ones Grinding jets 4.16 and 4.17 parallel to the axis of rotation 4.21 of the system are blown so that the centrifugal forces act laterally on the fluid bed in the grinding chamber and whose solid particles in the area between the grinding nozzles the grinding rays crowd.

While in the two embodiment according to FIG. 4, the regrind task in the axial direction at an outer end of the inlet pipe 4.12 takes place and the fine material exits the fines outlet nozzle, which is also axial and coaxial with the inlet pipe on the other side of the mill housing 4.2, 4.9 is arranged in the embodiments 5 regrind 5.11 and fines outlet 5.10 on the same side of the mill housing. Otherwise it is the same 5 of the system of FIG. 4, which is indicated by the reference numerals is expressed, again the embodiment below the center line 5.21 the embodiments according to Figures 1 to 3, while the embodiment above the center line is the same as the embodiment that 4 above the center line 4.21, i.e. the centrifugal force supports the introduction of solid particles from the fluid bed into the grinding jets.

What is essential in the embodiments according to FIGS. 1 to 3 and 4 and 5 above the center line or axis of rotation that the maelstrom directed radially inward into the fluid bed enter and onto the solid particles to be ground and sifted a counterforce acts due to centrifugal force.

4 and 5 show in their below the The axis of rotation 4.21 and 5.21 lying parts of the previous ones Designs corresponding embodiments, in which means an acceleration nozzle 4.14 or 5.14, as one of two forming a pair of nozzles and diametrically opposed to each other Nozzles a fluid jet with high flow 4.6 or 5.6 to penetrate perpendicular to the axis of rotation Fluid bed 4.3 or 5.3 causes particles from the fluid bed to be sucked in by energy exchange especially in the fluid jet be disassembled, with a centrifugal force due to rotation the particles around the axis of rotation 4.21 or 5.21 Area of the nozzle outlet stops in such a way on the Particle concentration in the beam. Furthermore 4 and 5 show in their above the axis of rotation 4.21 or 5.21 lying parts other embodiments in which in another way the centrifugal force acting on the particle distribution is brought in the beam. The centrifugal force supports the suction of the particles along the entire beam length from the fluidized bed into the fluid jet with high energy flow in that the suction and centrifugal force in the same direction on the blasting center line and consequently more particles get into the grinding mill than it does by the flow energy of the grinding jet alone or in Milling jet prevailing negative pressure happens, as is usual with Jet mills with a non-rotating mill housing are the case is.

The effect of the rotation of the mill or the resulting centrifugal force can Fig. 6 with the Sub-figures 6A and 6B are removed. 6A can be seen like the hydrostatic or quasi-hydrostatic pressure (corresponding to gas or liquid as a fluid) through the arrows 6.P, over the length 6.L of the grinding jet 6.6, whose longitudinal axis 6.61 with the axis of rotation 6.21 of the mill in the 6A includes a right angle, radially rises from the inside out and in the area of the outlet the nozzle 6.4 is the largest. The suction effect for the Particles in the grinding jet supportive, from the centrifugal force resulting hydrostatic pressure is therefore directly at the nozzle outlet largest, in an area in which according to previous State of the art no particles sucked in from the fluidized bed are present in greater numbers, so the hydrostatic presses Highly pressure particles in the grinding jet.

The resultant one that is optimal for the grinding process Pressure curve in the grinding jet results from Fig. 6b. 6.P1 is the pressure of the material to be ground in front of the nozzle, 6.P2 the pressure curve under centrifugal force, 6.P3 the pressure curve without Centrifugal force influence in the diagram in which the radius r over the pressure P is plotted.

Claims (14)

Process for fluidized bed jet milling in a fluid suspended particulate regrind using at least one energy-intensive penetrating into the fluid bed Fluid jets (6.7) and using measures to influence the particle concentration in the range of at least an energetic entering the fluidized bed Fluid jet (6, 7), characterized in that the measure the application to influence the particle concentration a centrifugal force (18) on the particles in the area of the at least one fluid jet (6, 7). A method according to claim 1, characterized in that the centrifugal force is essentially perpendicular to the direction of the jet is brought to the suction of the Beam on solid particles of the fluid bed in the surrounding area of the jet by the of the centrifugal force back pressure caused to support the entire beam length. A method according to claim 1, characterized in that the centrifugal force is essentially the direction of the fluid jet is opposite with the goal of creating a gradient the particle concentration along the beam direction bring about, with the highest concentration preferred occurs in the immediate area of the beam entry. Device for performing the method according to claim 1 and one of claims 2 and 3, characterized in that the fluidized bed (3) is enclosed by a housing (1.2.1) is that used to generate one on the fluid bed in the area of the energy-intensive entering the fluidized bed at least a fluid jet (6, 7) about an axis (2.21) rotates, to which preferably or substantially perpendicular the at least one fluid jet (23.16; 2.17) into the fluidized bed, essentially counter to the centrifugal force to Penetration is brought. Apparatus according to claim 4, characterized in that the rotating housing (2.1) is an inner housing (2., 2), which is surrounded by an outer housing (2.3), in which Area (2.5) between the inner housing (2.2) and the outer housing (2.3) generates an overpressure and maintains it for the operating time that is sufficient, at least one, with high energy in the inner housing (2.2) to feed the incoming fluid jet (2.16, 2.17). Apparatus according to claim 4, characterized in that Inner housing (2.2) and outer housing (2.3) rotatably together are connected. Device according to claim 5 or 6, characterized in that that the cylindrical outer housing (2.3) in a cover plate Provide concentrically with an inlet connection (2.18) is through which the medium of at least one is energetic fluid jet (2.16, entering the inner housing (2.2), 2.17) in the area between the two housings (2.2, 2.3) reached. Apparatus according to claim 7, characterized in that an inlet pipe concentrically in the inlet connection (2.18) (2.8) is arranged, through which the regrind in the grinding chamber (2.6) enclosed by the inner housing (2.2) reached. Device according to claims 7 and 8, characterized in that that coaxially in one of the first mentioned cover plates of the outer housing (2.3) opposite the outlet Cover plate of the outer housing (2.3) an outlet (2.10) is arranged for the floured good. Device according to one of claims 8 and 9, characterized in that that to the outlet opening on the grinding chamber side of the regrind inlet pipe (2.8) a guide device (2.12) within the grinding chamber (2.6) is arranged, which in the Grinding material reaching the area of the at least one that is introduced into the grinding chamber (2.6) with high energy Grinding jet (2.16, 2.17) arrives. Apparatus according to claim 9, characterized in that the inlet opening of the outlet connection on the grinding chamber side (2.10) a guide device for the ground material (2.13) upstream which is the shipment of the to exit from the grinding chamber (2.6) certain grinding material into the area the inlet opening of the outlet nozzle (2.10) favors. Plant with a device according to one of claims 4 to 11 for performing the method according to claim 1 and one of claims 2 and 3, characterized in that the ground material is fed to a classifier (3.25) with a predetermined separation limit, which is below this Borderline, coarser property of that of the fluid bed jet mill regrind to be fed is fed again and that fine material of further processing above this limit, for example in a filter. Plant according to claim 12, characterized in that the Sifter a functionally separate from the mill interacting wind sifter (3.25). Plant according to claim 12, characterized in that the Sifter a wind sifter built into the mill (4.13).

Images