DE102009057079A1 - Hydrocyclone assembly, underflow nozzle with approach or extension piece for a hydrocyclone, and method of operating a hydrocyclone assembly - Google Patents

Abstract

The invention relates to a hydrocyclone arrangement with a, in particular tangential inlet of the feed pulp, a headrace 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. According to the invention, 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. Furthermore, a choke valve is optionally formed on the upper flow to influence the flow of solids to the underflow such that at a detected transition from strand to Schirmaustrag at the lower reaches after activating the additional water supply a close lying on the screen Strangaustragszustand is set.

Description

The The invention relates to a hydrocyclone arrangement with an inlet of the Feed sludge, an upper run for the fine grain discharge, a conical-cylindrical underflow for coarse grain discharge and a sensor for detecting the beam shape or the beam envelope on coarse grain discharge according to the preamble of the claim 1. Furthermore, the invention relates to an underflow nozzle with approach or extension piece according to the Feature combination according to claim 8 and a method for Operating a Hydrozyklonanordnung according to the The jig of claim 11, wherein the subclaims are at least expedient refinements and developments represent.

Known Hydrocyclones have a tangential inlet of the feed pulp in a cylindrical-conical process space and two discharges the separation products into a fine grain overflow and a coarse grain underflow on. Such cyclones are used to polydisperse suspensions if possible with a desired grain size to classify strictly. At the desired classification exist physical limits. This concerns especially the solid particles in the micrometer range, with the aqueous Medium with the coarse grain are discharged, but also coarse grains, which are not completely separable in the lower reaches.

The DE 199 63 284 A1 as well as the PCT WO 00/25933 A1 show a Hydrozyklonanordnung and an associated method of operation, wherein the hydrocyclone assembly has an inlet of the feed pulp, an upper course and an underflow, wherein the inlet is guided by a pump in a receiving chamber.

Of the Overflow is directed into a collection chamber and for the Underflow is a free run available. According to the There teaching are several, preferably equally sized hydrocyclones provided and arranged so spatially close to each other, that the headwaters of these hydrocyclones in the for they lead to common headbox chamber, with the headbox chamber is designed as a pressure pot and an overflow header with an adjustable control valve and an associated Control device for adjusting the volume split, namely the ratio of the volume flows of upper and lower reaches, cooperates.

It there is exploited the fact that a hydrocyclone depending on different amounts of solids from its operating state in its conical, lower section stores. Through the coupling of several hydrocyclones of smaller design in the overall hydrocyclone assembly the capacity is increased overall, with the required construction effort is low. From the recorded mass the stored sediment in the hydrocyclone cone can be a controlled variable be derived for the volume split by an appropriate Interaction with the aforementioned control valve in the manifold the upstream flow of the hydrocyclone (s) in the case of a hydrocyclone battery will be produced. The mass of stored solid in the hydrocyclone cone Determines the extent to which coarse grain in the fine grain discharge of Hydrozyklonvorlaufs is separated and thus the separation grain size of the Hydrocyclones rises.

As optimal operating point is in the DE 199 63 284 A1 stated that this is given when, with free discharge of the coarse grain flow in the hydrocyclone underflow, the shape of the discharge jet turns from a strand to a so-called screen. As long as 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.

For the determination of the jet shape at the underflow, according to DE 100 27 976 C2 proposed to form a special arrangement for scanning the underflow, 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.

From the company FLSmidth Krebs, USA, under " www.krebs.com/product "An additional device for the reduction of fine sludge proportions in the lower reaches of a hydrocyclone presented and offered. According to this solution, a cylindrical intermediate piece is used in the lower part of the hydrocyclone cone, comprising a device for the tangential supply of washing water. This additional wash water dilutes the suspension with respect to the turbulently mixed fine particles contained therein. This dilution causes the fine particle concentration in the coarse-grain discharge to be reduced. However, the desired positive effect of this water supply measure is limited, which is mainly due to the fact that only defined additional amounts of water can be added, otherwise more coarse grains are pushed to the cyclone center and thus in the upper reaches. Furthermore occurs in undesirable Wei Make a dilution in the lower run. In the conical part of the additional water is distributed over a relatively large radius, which indeed reduces the dilution effect, on the erroneous discharge of coarse grains in the lower reaches, however, can not be influenced.

Out The above, it is therefore an object of the invention, a further developed Hydrozyklonanordnung and a method for operating such To provide an arrangement which improves the separation such that both the erroneous discharge of fine grain in the underflow and the coarse grain is reduced in the upper reaches, without the disadvantages described of the prior art occur.

The Solution to the problem of the invention is achieved by a hydrocyclone arrangement according to the combination of features according to claim 1, by a, also retrofittable, approach or extension piece for or such an extended underflow nozzle according to the feature combination according to claim 8 and with a method according to the teaching of Claim 11, wherein the dependent claims at least expedient Embodiments and developments include.

Therefore is from a Hydrozyklonanordnung with one, in particular tangential Inlet of the task sludge assumed, which is an upper course for the Feinkornaustrag, a conical-cylindrical trained Underflow for coarse grain discharge and a sensor for detection the jet shape or the beam envelope at coarse grain discharge comprises.

According to the invention in the area of the transition from conical to cylindrical Part of the underflow means for the directed feeding of Provided additional water.

Farther can with particularly problematic task conditions with large fluctuations in the upper course a throttle valve or be formed a throttle of defined size, to influence the flow of solids to the underflow, in such a way that after activating the auxiliary water supply in the range low screen angle, near the transition screen / strand is working.

Ausgestaltend the make-up water is provided via a control valve, wherein a regulator unit with both the auxiliary water control valve as well as with the upper-flow throttle valve in effective connection stands.

The Allow means for directed feeding of make-up water a superposition of given in the cyclone cross-flow classification with a countercurrent classification, whereby in the centrifugal field of the cyclone through the additional water directed to the center radial flow which is generated by an axial upward flow directed towards the center is accompanied.

The Means for supplying the make-up water are in particular formed as nozzle-like bores, wherein the nozzles evenly spaced, one or more rows be formed circumferentially at the lower reaches.

The nozzle-like bores have a relation to the underflow cross section tangential orientation and have a radial and axial Angle of attack for defined flow generation.

at In one embodiment, the holes of an annular Faceplate sealed, with the forend simultaneously the water connection, the water distribution and water supply is used.

The Sensors for steel mold analysis can be an optical detector and / or have a vibration detector. The vibration detector is immediate mounted on the hydrocyclone and is in acoustic communication with this. With such vibration detectors, it is possible to very sensitive to the sediment level in the hydrocyclone cone.

The Inventive, also retrofittable underflow nozzle extension for hydrocyclones known per se 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 area between the conical and cylindrical cross-section has circumferentially and spaced nozzle-like openings, which a tangential-radial orientation in the center direction and a Axial angle of attack to the desired countercurrent classification in the centrifugal field of the hydrocyclone.

The nozzle-like openings can in one, but evenly spaced in several rows be formed and located in the area of a circumferential annular groove.

The annular groove is sealingly surrounded by a circular ring forend, wherein an annular additional water serving space is formed between the forend and the annular groove. Forearm z. B. a nozzle available to feed additional water accordingly. Due to the two-part design of the underflow nozzle with the special nozzle-like openings within an annular groove and the sealing-Kreisringstulp is a easy production possible and guaranteed access to the nozzle-like openings at any time.

at the method of operation according to the invention The above-explained hydrocyclone arrangement is first running or in cyclic intervals the beam shape at Coarse grain discharge monitored to activate the make-up water feed to recognize a changing beam shape. For stabilization the desired strand discharge, it is possible to to reduce the suspension pressure to the underflow. Therefor the throttle valve can be opened at the upper reaches and / or the Additional water supply are regulated. By using optical Sensors can be the beam shape, especially the beam angle very be determined exactly. The aim is one of the application dependent desired beam shape of the underflow discharge, preferably near the transition screen / strand.

The Additional amount of water is always dependent of the suspension density and the grain size composition regulated to be classified discontinued solids flow.

at A throttling of the valve at the upper reaches can to obtain the desired Task throughput the performance of an existing task feed pump be increased at least temporarily.

The Invention will be described below with reference to an embodiment and explained in more detail with the aid of figures become.

in this connection demonstrate:

1 a schematic diagram of the hydrocyclone arrangement according to the invention with control components for operating the hydrocyclone according to the invention;

2 a cross-sectional view and a longitudinal sectional view of the provided with the nozzle-like holes according to the invention underflow and symbolically represented angles of attack for the targeted introduction of additional water and

3 typical separation characteristics in hydrocyclone classification.

Of the inventive approach, which with the following Embodiment will be explained again is, is targeted, additional water flow directed into the hydrocyclone, in particular pumping. in this connection It is crucial that the placement point as far as possible in the direction of the underflow discharge. So it is true the additional water connection at the underflow nozzle or a To arrange approach or extension piece, and although near the transition from the conical part to the cylindrical one Outlet of the corresponding underflow nozzle. In this area there is a dense fluidized bed of sediment. With optimal dosage the make-up water can be produced at this point a fluidized bed countercurrent classification which are responsible for both the reduction of fine grain and an increased deposition of coarse grain in the lower reaches leads.

in this connection it succeeds, with a relatively small amount of added water a very to achieve great effect, since the radial cross-section essential smaller than in the larger one above Cone area. The positive effect on coarse grain separation is due to the following causes.

By the displacement of the fine grain becomes cloud density and turbidity viscosity and thus the sedimentation of coarse grain reduced.

Also has a misguided coarse grain on the way to the headwaters to cover further distance and therefore again centrifigurated towards the hydrocyclone wall. The thus designed Hydrocyclone then reacts sensitively to make-up water, the farther one goes moves towards coarse grain discharge. It exists basically the risk that the additional water in the Underflow breaks through and leads to an undesirable dilution of coarse grain leads. There is also the danger of a breakthrough in the upper reaches with corresponding Fehlaustrag.

to Avoiding these disadvantages is a targeted control intervention made, which will be explained in more detail.

Essential for the supply of make-up water are number, Arrangement and orientation of the feed channels, which are preferably designed as bores.

there It is important to note that the introduction of make-up water should be done so that the cyclone flow is not in undesirable Way is disturbed. For this one is possible large number of feed channels or Provide supply holes, each in the same Condition and in several superimposed rows over the circumference of the underflow nozzle are arranged distributed.

The basic orientation of the feed channels or feed holes follows the tangential flow in the cyclone. Here, an essential idea of the invention is to effect a superimposition of the cyclone, preferably cross-flow classification, by a countercurrent classification, which operates very precisely tet.

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 α with a radial angle of attack 2 purposefully influenced.

Another prerequisite for the success of the countercurrent classification is that in the center of an axial upflow and on the wall provides an axial outflow for the removal of the separation products. This in turn is achieved by an axial angle β of the feed channels in either the positive or negative direction, as also in the 2 , lower part of the picture, is shown.

Regarding operating the hydrocyclone assembly according to the invention First, a hydrocyclone monitoring, and related on the shape of the free underflow discharge. Can be used here come optical sensors that scan the discharge. But also Vibration or vibration sensors are suitable in accordance with sensitive Way to react to the sediment level in the hydrocyclone cone.

Of the Discharge jet of the underflow has either the shape of a screen or a strand. When working with additional water offers the Discharge with low screen angle or the strand discharge near the transition optimal conditions for the umbrella. As is known, the solids content in the underflow at Schirmaustrag higher, resulting in a lower Faulty discharge leads to fine grain.

in principle results from the supply of make-up water a dilution of the lower course, whereby its shape tends more to Schirmaustrag. This is counteracted in critical cases by a Throttle valve in the upper reaches is opened. In this way manages the suspension pressure in the underflow nozzle and thus also to reduce the flow of solids in the lower reaches, so that sediment is dammed again and the discharge jet returns to the strand form.

The Additional water is here on the solids flow, the suspension density and the given grain size composition matched. As in this regard, the operating conditions inevitably change during the use of the hydrocyclone, In the case of an advanced control, the additional water flow is also used influenced by a valve. With low-fluctuation feed stream the effort can be reduced and only one of the mentioned valves one Subject to regulation, while the other valve is set to a constant value.

The Control in the upper reaches has the advantage that with multiple circuits in hydrocyclone batteries one valve for all hydrocyclone overflows is sufficient if this summarized in a collecting pot become. The inlet or additional water control has in contrast the advantage that the expense of the valve on the single cyclone relatively low and that each individual cyclone individually adjustable is.

Of the granted hydrocyclone with control according to the invention stable conditions regarding fluidized bed height, Fluidized bed density and countercurrent velocity. The throttling of the Valve in the upper reaches can cause an increased pressure drop lead, resulting in lower throughput of the cyclone is accompanied. This disadvantage can be counteracted by the pressure drop between inlet and upper reaches with the help of a corresponding Measuring device determines and increasing the speed of the Feed pump of the hydrocyclone is made.

The Advantages according to the invention of the described hydrocyclone arrangement consist in that the cyclone by means of a regulated additional water dosage has greatly improved release properties, such as countercurrent classification correspond. As a result, both better product yields than also better product qualities with regard to a desired Grain size composition achieved. It can So also flow diagrams and separation technologies simplified become, because so far high separating sharpness either by multilevel Cyclone circuits or the interconnection of cyclones with upstream classifiers were achieved.

The necessary technical or constructive changes on the cyclone itself are relatively low, since no new components required and only one underflow nozzle to be modified accordingly got to. So it offers itself the presented teaching also for the retrofitting of existing plants.

Of the required regulatory effort is limited, since for the regulation of the addition of water and for the Sensors resorted to commercially available products can be. Compared to operation of the cyclone without regulated Additional water flow is also a reduction of the separation grain sizes possible.

1 showed a schematic representation of a hydrocyclone.

The hydrocyclone body 15 goes into a funnel-shaped area 16 over, with the funnel-shaped area 16 as underflow nozzle 1 is designed.

At the conical end of the underflow nozzle 1 are holes 2 designed to make additional water under pressure 3 introduce.

Of the Diameter of the underflow nozzle is chosen that discharged without additional water of the lower reaches stranded becomes.

After connecting the make-up water 3 the underflow discharge changes to the umbrella shape 5.2 , The strand shape is denoted by the reference numeral 5.1 Mistake.

The make-up water 3 is via a valve assembly 6 the holes 2 supplied for the additional water, wherein the additional water valve 6 via a first control unit 17 is pressed.

The particular shape of the underflow jet 5.1 or 5.2 is using either an optical detector 4 or with the help of a vibration detector 11 determined. The corresponding detector 4 or 11 provides the signals for the actuation of the actuators, namely the control valve 6 and the throttle valve in the upper reaches 7 ,

The throttle valve 7 in the upper course, which is never completely closed when the cyclone functions, leads to a reduced suspension pressure on the underflow discharge and thus to a braked flow of solids to the underflow nozzle. As a result, sediment is dammed again and the discharge line returns to the strand form 5.1 back.

The countercurrent classification in the fluidized bed of the accumulated sediment works best when the output line is close to the transition to the screen discharge. This is detected by the optical sensor 4 as occasional penetration of the screen or the at least one vibration detector 11 by registering resonant vibrations of the hydrocyclone body 15 ; 16 ,

It It should be noted in this context that in countercurrent classification in a fluidized bed in contrast to conventional hydrocyclones the sharpest separation is achieved at Strandaustrag. Thus, it is advantageously possible, even at high Feed solid contents at the same time high thickening and high To achieve selectivity.

The This regulation is necessary because there are small fluctuations the properties of the feed pulp in terms of solids content and / or grain size composition countercurrent classification to disturb.

At relatively stable task conditions but the effort can be reduced to the effect that in the upper reaches a constant throttling is specified and the stabilization of the strand shape in the lower course solely by pressing the control valve 6 is reached for the supply water flow.

The feed pulp is made with the help of a feed pump 13 to the inlet 18 at the hydrocyclone body 15 promoted. The upper run with fine grain discharge is denoted by the reference numeral 19 Mistake.

Pressure measuring devices 12 determine the pressure conditions, in particular a pressure drop between inlet 18 and upper reaches 19 , This is done with the help of the second controller 20 the speed and thus the power of the feed pump 13 adapted, especially increased in pressure drop.

With the reference number 10 is a ring segment indicated that a uniform supply and feeding the make-up water to the holes 2 allows.

The 2 shows by way of example the arrangement and the angle of attack of the selected holes in the underflow nozzle for additional water supply.

2 , upper part of the picture, shows a horizontal section with recognizable eight holes (arrow representations), which are distributed at the same distance over the circumference of the nozzle.

The teaching according to the invention requires that by a radial angle of attack for the countercurrent separation required radial component of the flow is generated.

Like from the 2 can be seen, this radial angle of attack α is measured to the tangent to the inner wall of the cyclone.

2 , below, shows a vertical section of the underflow nozzle. The holes can be on two levels, z. B. the level 100 and 200 be provided, wherein an axial angle β for the corresponding hole (again arrow view) is selected. This axial angle β can have a positive, but also a negative sign. Depending on the choice of sign, either the axial flow in the outer vortex directed toward the lower reaches is intensified, or the axial flow of the inner vortex in the cyclone directed towards the upper flow is increased. The appropriate choice of the angle of attack takes place in dependence on the respective Hydrozyklongeometrie.

The 3 shows typical separation curves in an inventively realized hydrocyclone classification.

The separation curves indicate with which Probability the individual grain sizes are discharged in the lower reaches.

As can be seen, 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 the values at an ideal separation.

The Curve b follows a typical course as it is through use the controlled countercurrent separation is achieved in the cyclone. there is an approximation to the ideal course both in the fine grain and also to observe in the coarse grain area. This is due on the construction according to the invention and the Operating procedure of the hydrocyclone. So it receives the Hydrocyclone in terms of its release properties a new quality, which make it possible to open up further fields of application.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 19963284 A1 [0003, 0006]
• WO 00/25933 A1 [0003]
• - DE 10027976 C2 [0007]

Cited non-patent literature

• - www.krebs.com/product [0008]

Claims (13)

Hydrozyklonanordnung with a, in particular tangential inlet of the feed pulp, a headrace 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, characterized in that in the region of the transition from conical to cylindrical Part of the underflow means are provided for the directed supply of make-up water, wherein the make-up water is provided via a control valve. Hydrocyclone arrangement according to claim 1, characterized in that that at the upper reaches a throttle valve is formed to the flow of solids to influence the underflow such that at a detected transition from strand to screen discharge at the underflow after activating the additional water supply a Strandaustragszustand located near the screen or a discharge state is set with a low screen angle, wherein a Regiereinheit both with the auxiliary water control valve and the upper-flow throttle valve communicates. Hydrozyklonanordnung according to claim 1 or 2, characterized in that the means for directed feeding of the make-up water a superposition of the given in the cyclone Allow cross flow classification with a countercurrent classification, wherein for this in the centrifugal field of the cyclone by the additional water producing a radial flow directed to the center, which accompanies by an axial upward flow directed to the center is. Hydrocyclone arrangement according to one of the preceding Claims, characterized in that the means for Supply of additional water nozzle-like holes are equally spaced, one or multi-row circumferentially arranged at the lower reaches. Hydrozyklonanordnung according to claim 4, characterized in that that the nozzle-like bores tangentially with respect to the underflow cross-section Have alignment and a radial (α) and a axial (β) angle of attack for defined flow generation have. Hydrozyklonanordnung according to claim 4 or 5, characterized characterized in that the bores of an annular Faceplates are sealed, with the forend at the same time the water connection and the water distribution serves. Hydrocyclone arrangement according to one of the preceding Claims, characterized in that the sensor a comprises optical detector for beam shape analysis and / or a vibration detector, the latter being directly acoustically coupled to the cyclone. Shoulder or extension piece for an underflow nozzle for a hydrocyclone with a nozzle cross-sectional profile, which in axial Direction from conical to cylindrical changes, characterized that in the transition region between the conical and the cylindrical cross-section circumferentially and spaced nozzle-like openings formed which are a tangential-radial orientation in the center direction and have an axial angle of attack. Underflow nozzle according to claim 8, characterized that the nozzle-like openings in one or formed a plurality of rows evenly spaced are and are in the range of an annular groove. Underflow nozzle according to claim 9, characterized in that the annular groove is sealed by a circular ring forend is surrounded, between forend and annular groove an annular Additional water serving space is formed and at the forend a make-up water feed is arranged. Method for operating a hydrocyclone arrangement according to one of claims 1 to 7, characterized that constantly monitors the beam shape at the coarse grain discharge to change the activation of the additional water supply a modified beam shape to recognize, with the stabilization of the desired strand discharge reduces the suspension pressure to the underflow and this an existing throttle valve on the upper reaches opened and / or a regulation of the additional water supply takes place. Method according to claim 11, characterized in that that the additional water amount depending on the suspension density and the grain size composition of the to be classified regulated solids flow is controlled. Method according to claim 11 or 12, characterized that when throttling the valve in the upper reaches to obtain the desired Task throughput affects the performance of a task feed pump, in particular is increased.