Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
  • B04C—APPARATUS USING FREE VORTEX FLOW, e.g. CYCLONES
  • B04C5/00—Apparatus in which the axial direction of the vortex is reversed
  • B04C5/14—Construction of the underflow ducting; Apex constructions; Discharge arrangements ; discharge through sidewall provided with a few slits or perforations
  • B04C5/18—Construction of the underflow ducting; Apex constructions; Discharge arrangements ; discharge through sidewall provided with a few slits or perforations with auxiliary fluid assisting discharge
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
  • B04C—APPARATUS USING FREE VORTEX FLOW, e.g. CYCLONES
  • B04C11/00—Accessories, e.g. safety or control devices, not otherwise provided for, e.g. regulators, valves in inlet or overflow ducting

Definitions

• the invention relates to a hydrocyclone arrangement with an inlet ofoccasiontrübe, an upper course for the fine grain discharge, a conical cylindrical underflow for coarse grain discharge and a sensor for detecting the beam shape or the jet envelope on coarse grain discharge according to the preamble of claim 1. Furthermore, the invention relates to an underflow nozzle with approach or extension piece according to the combination of features according to claim 8 and a method for m operating a hydrocyclone assembly according to the teaching of claim 11, wherein the dependent claims represent at least expedient refinements and developments.
• Known hydrocyclones have a tangential inlet of the feed pulp in a cylindrical-conical process space and two discharges of the separation products in a fine grain overflow and coarse grain underflow.
• Such cyclones are used to classify polydisperse suspensions as close as possible to a desired particle size.
• the desired classification has physical limits. This concerns above all the solid particles in the micrometer range, which are discharged with the coarse grain with the aqueous medium, but also coarse grains, which are not completely separable in the underflow.
• the upper-head collecting chamber is designed as a pressure pot and an overflow collecting line with an adjustable Control valve and an associated control device for the adjustment of the volume split, namely the ratio of the flow rates of the upper and lower reaches, cooperates.
• a hydrocyclone depending on its operating state stores different amounts of solids in its conical lower section.
• the capacity is increased overall, the required structural complexity is low.
• a control variable for the volume split can be derived by establishing a corresponding interaction with said control valve in the collecting line of the top stream of the hydrocyclone or hydrocyclone in the case of a hydrocyclone battery.
• the mass of the stored solid in the hydrocyclone cone determines to what extent coarse grain is separated into the fine grain discharge of the hydrocyclone overflow and thus increases the separation grain size of the hydrocyclone.
• DE 199 63 284 A1 states that this is given as the optimum operating point when, with free discharge of the coarse grain stream in the hydrocyclone underflow, the shape of the discharge jet turns from one strand to a so-called screen.
• the strand shape can be observed in the lower reaches, sediment is still stored in the cone, which on the one hand means a high solids content or a high thickening in the lower reaches, on the other hand entails an at least partial spillage of this coarse-grained material in the lower reaches.
• DE 100 27 976 C2 proposes to design a special arrangement for scanning the underflow jet, which is designed as a measuring probe.
• the measuring probe is located in a housing, wherein the housing has a flexible membrane on its side facing the beam or is terminated with such.
• the membrane is then subjected to deformation upon impact of the jet.
• An arranged inside the housing sensor can then detect the deformation, so that a conclusion on the corresponding beam shape or the beam shape change is possible.
• a hydrocyclone arrangement with a, in particular tangential inlet of the feed pulp, which comprises an upper course for the fine grain discharge, a conical-cylindrical underflow for coarse grain discharge and a sensor for detecting the jet shape or the jet envelope on Coarse grain discharge.
• means for directional supply of make-up water are provided in the region of the transition from the conical to the cylindrical part of the underflow.
• a throttle valve or a throttle of defined size be formed to influence the flow of solids to the lower reaches, in such a way that after activation of the additional water supply in the field low screen angle, near the transition screen / strand is working.
• Ausgestaltend the make-up water is provided via a control valve, wherein a control unit is in effective connection with both the auxiliary water control valve and the upper-flow throttle valve.
• the means for the directional feeding the make-up water allow a superposition of given in the cyclone cross-flow classification with a countercurrent classification, for this purpose in the centrifugal field of the cyclone by the Make additional water is directed to the center radial flow, which is accompanied by a directed to the center axial upflow.
• the means for supplying the make-up water are designed in particular as nozzle-like bores, wherein the nozzles are uniformly spaced, one or more rows are formed circumferentially at the underflow.
• the nozzle-like bores have a tangential with respect to the underflow cross-section and have a radial and axial angle of attack for defined flow generation.
• the holes may be sealed by an annular Stülp, the Stülp simultaneously serves the water connection, the water distribution and water supply.
• the sensor for steel mold analysis may comprise an optical detector and / or a vibration detector.
• the vibration detector is mounted directly on the hydrocyclone and is in acoustic communication with it. With such vibration detectors, it is possible to react very sensitively to the sediment level in the hydrocyclone cone.
• the inventive, retrofittable underflow nozzle extension for known hydrocyclones has a nozzle cross-sectional profile, which changes in the axial direction from conical to cylindrical, wherein the discharge takes place at the cylindrical end.
• the transition region between the conical and cylindrical cross-section has circumferentially and spaced nozzle-like openings which have a tangential-radial orientation in the center direction and an axial angle of attack to ensure the desired countercurrent classification in the centrifugal field of the hydrocyclone.
• the nozzle-like openings may be uniformly spaced in one, but also in several rows and be in the region of a circumferential annular groove.
• the annular groove is sealingly surrounded by a circular ring forend, wherein between Stülp and annular groove, an annular beaushispeiseraum is formed.
• Stülp is z.
• the jet shape at the coarse-grain discharge is initially monitored continuously or at cyclic intervals in order to detect a changing beam shape when the additional-water feed is activated.
• the throttle valve can be opened at the upper reaches and / or the soiriganeinspeisung be regulated.
• the beam shape, in particular the beam angle can be determined very accurately.
• the aim is a dependent on the application case desired beam shape of the underflow discharge, preferably near the transition screen / strand.
• the additional water quantity is generally regulated as a function of the suspension density and the grain size composition of the discontinued solids stream to be classified.
• Fig. 1 is a schematic diagram of the hydrocyclone arrangement according to the invention with control components for operating the hydrocyclone according to the invention;
• Fig. 2 is a cross-sectional and a longitudinal sectional view of the nozzle-like holes provided with the underflow and symbolically represented angles of attack for the targeted introduction of the additional water and
• Fig. 3 typical separation characteristics in the hydrocyclone classification.
• the approach according to the invention consists of specifically introducing additional water flow-oriented into the hydrocyclone, in particular pumping it in. It is crucial that the point of introduction is laid as far as possible in the direction of the underflow discharge. It is therefore necessary to arrange the additional water connection to the underflow nozzle or a neck or extension piece, near the transition from the conical part to the cylindrical outlet of the corresponding underflow nozzle. In this area there is a dense fluidized bed of the sediment. With optimal dosing of make-up water, a fluidized bed countercurrent classification can be generated at this point, which leads both to a reduction of the fine grain and to an increased separation of the coarse grain in the underflow.
• a misoriented coarse grain has to travel a further distance on the way to the upper run and can therefore be centrifigured again in the direction of the hydrocyclone wall.
• the thus designed hydrocyclone then reacts sensitively to make-up water, the further one moves in the direction of coarse grain discharge.
• the additional water breaks through in the lower reaches and leads to an undesirable dilution of the coarse grain.
• Essential for the supply of additional water are number, arrangement and alignment of the feed channels, which are preferably formed as bores.
• H is an essential idea of the invention is to effect a superposition of the cyclone taking place preferably cross-flow classification by a countercurrent classification, which operates very segregated.
• the prerequisite for a desired countercurrent classification in the centrifugal field of the hydrocyclone is the generation of a radial flow directed towards the center. This radial component of the additional water flow is influenced in a targeted manner with a radial angle of attack ⁇ according to FIG. 2.
• a hydrocyclone monitoring takes place, specifically based on the form of the free underflow discharge.
• optical sensors can come here, which scan the discharge.
• vibration or vibration sensors are also suitable for reacting sensitively to the sediment level in the hydrocyclone cone.
• the discharge jet of the underflow is in the form of either a screen or a strand.
• the discharge with a small screen angle or the strand discharge close to the transition to the screen offers optimum conditions.
• the solids content in the underflow at Schirmaustrag is higher, which leads to a lower erroneous discharge of fine grain.
• the control in the upper reaches has the advantage that in multiple circuits in hydrocyclone batteries, a valve is sufficient for all hydrocyclone overflows, if they are combined in a collecting pot.
• the supply or additional water control has the advantage that the cost of the valve on the cyclone is relatively low and that each individual cyclone is individually controlled.
• the inventive hydrocyclone with control provides stable conditions in terms of fluidized bed height, fluidized bed density and countercurrent flow.
• the throttling of the valve in the upper reaches can lead to an increased pressure drop, which is accompanied by a lower throughput of the cyclone.
• This disadvantage can be counteracted by the pressure drop between inlet and upper reaches determined by means of a corresponding measuring device and an increase in the speed of the feed pump of the hydrocyclone is made.
• the advantages of the described hydrocyclone arrangement according to the invention consist in the fact that the cyclone has greatly improved separation properties by means of a controlled addition of added water, as they correspond to a countercurrent classification. As a result, both better product yields and better product qualities are achieved with respect to a desired grain size composition. It can also flow diagrams and separation technologies are simplified because previously high Separation sharpness either by multi-stage cyclone circuits or the interconnection of cyclones were achieved with upstream classifiers.
• the required regulatory effort is kept within limits, as can be used for the regulation of the water additive and for sensors on commercial products. In comparison to an operation of the cyclone without regulated additional water flow, a reduction of the separation grain sizes is also possible.
• Fig. 1 shows a schematic representation of a hydrocyclone.
• the hydrocyclone body 15 merges into a funnel-shaped region 16, wherein the funnel-shaped region 16 is configured as underflow nozzle 1.
• the diameter of the underflow nozzle is selected so that the underflow is discharged strand-shaped without additional water.
• the strand shape is provided with the reference numeral 5.1.
• the additional water 3 is supplied via a valve arrangement 6 to the holes 2 for the additional water, wherein the additional water valve 6 is actuated via a first control unit 17.
• the respective shape of the underflow jet 5.1 or 5.2 is determined either by means of an optical detector 4 or by means of a vibration detector 11.
• the corresponding detector 4 or 11 supplies the signals for the actuation of the Stellg songs, namely the control valve 6 and the throttle valve in the upper reaches. 7
• the countercurrent classification in the fluidized bed of the accumulated sediment is best achieved when the output line is close to the transition to the screen discharge. This detects the optical sensor 4 as an occasional penetration of the screen or the at least one vibration detector 11 by the registration of resonant vibrations of the hydrocyclone body 15; 16th
• Pressure measuring devices 12 determine the pressure conditions, in particular a pressure drop between inlet 18 and upper run 19. From this, the speed and thus the power of the feed pump 13 is adjusted with the aid of the second regulator 20, in particular increases in pressure drop.
• a ring segment is indicated, which allows a uniform supply and feeding the make-up water to the holes 2.
• the Fig. 2 shows an example of the arrangement and the angle of attack of the selected holes in the underflow nozzle for additional water supply.
• Fig. 2 upper part of the picture, shows a horizontal section with recognizable eight holes (Pfeildarstell ments), which are arranged distributed at the same distance over the circumference of the nozzle.
• the teaching according to the invention presupposes that the radial component of the flow required for countercurrent separation is generated by a radial angle of attack.
• this radial angle of attack ⁇ is measured to the tangent to the inner wall of the cyclone.
• Fig. 2 bottom, shows a vertical section of the underflow nozzle.
• the Bohru can gene on two levels, eg. B. the level 100 and 200, be provided with an axial angle ß for the corresponding hole (turn arrow) is selected.
• This axial angle ⁇ can have a positive, but also a negative sign.
• the axial flow directed towards the lower reaches in the outer vortex or there is an increase in the axial flow of the inner vortex in the cyclone directed towards the upper flow.
• the appropriate choice of the angle of attack takes place in dependence on the respective Hydrozyklongeometrie.
• FIG. 3 shows typical separation curves for a hydrocyclone classified according to the invention.
• the separation curves indicate the probability with which the individual particle sizes in the underflow are discharged.
• an ideal separation would be characterized by a vertical c at the cut-off grain size d 50 , which, however, does not correspond to physical reality.
• the curve a for the typical course of the separation curve of a conventional cyclone shows the known deviations in both the fine grain and the coarse grain range with respect to the values for an ideal separation.
• the curve b follows a typical course, as it is achieved by the use of controlled countercurrent separation in the cyclone.
• An approach to the ideal course can be observed in both the fine grain and the coarse grain range. This is due to the construction according to the invention and the operating method of the hydrocyclone. So it receives the hydrocyclone in terms of its release properties a new quality, which make it possible to develop other applications.

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• 2009
  • 2009-12-04 DE DE102009057079A patent/DE102009057079A1/de not_active Ceased
• 2010
  • 2010-02-03 EP EP10702304.6A patent/EP2393601B1/de active Active
  • 2010-02-03 WO PCT/EP2010/051271 patent/WO2010089309A1/de active Application Filing

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