EP2484451A2 - Solid bowl centrifuge with drying of solid cake - Google Patents

Abstract

The centrifuge (1) has an annular shell chamber (17) axially arranged above a drum cover (6). Connecting openings (19) are provided in the drum cover, and form a fluid channel for fluid or residual fluid (27) from solid cakes (3) to the shell chamber. The solid cakes are isolated at an inner side of a centrifuge drum (5). A residual fluid shell pipe (21) is arranged in the shell chamber. The pipe is designed such that the pipe is activated during a drying operation so that the fluid or the residual fluid from the chamber is drained in a drying operation by the pipe. An independent claim is also included for a method for separating solid-liquid-mixtures in a clear centrifugate and solid cakes by a solid bowl centrifuge.

Description

The invention relates to a solid bowl centrifuge, in particular for the sedimentation, which is used for separating solid-liquid mixtures (suspensions) in clarified centrifugate (clarified liquid) and a solid cake (sediment). Such a solid bowl centrifuge comprises a downwardly open solid bowl centrifuge drum rotatable about a vertical axis of rotation, a drum lid for closing the centrifuge drum and a centrifuge bowl arranged in the centrifuge bowl for withdrawing the centrifuge from the rotating centrifuge bowl during a sedimentation operation (cleaning operation) performed with the centrifuge.

For the separation of solid and liquid substances by the use of centrifugal force in centrifuges in addition to full-bowl centrifuges and drum centrifuges are known. Sieve drum centrifuges have a sieve-like perforated drum, which is sometimes covered with a filter cloth. They use the centrifugal force to squeeze the filtrate through the sieve or the filter material, whereby solids from the solid-liquid mixture, which can not pass because of their size, are retained. If the filtrate is the desired product, this is referred to as clarification filtration; in the case of separation filtration, the solid forming the solid cake is the desired product.

Screen drum centrifuges are very expensive overall in their construction. For this reason, it is known to use structurally less complicated Vollmantelzentrifugen for cleaning and separating solid-liquid mixtures in centrifugate and a solid cake.

During the sedimentation operation performed with the solid bowl centrifuge, i. during high-speed centrifugation of solid-liquid mixture fed to the rotary solid bowl centrifuge drum, separation into internal liquid clarified liquid (centrifugate) and external solid takes place by the centrifugal force. The solid settles in a continuously growing solid cake on the inside of the centrifuge drum, while the clarified liquid standing radially inwardly above it can be drawn off continuously by means of the centrifugal peeling tube. In the known Vollmantelzentrifugen, which are mostly oriented vertically, runs during centrifugation, the purified liquid via an overflow or an overflow edge or with a Zentrifugatschälrohr, which is set to a certain fixed diameter in the centrifuge or to a variable diameter in the centrifuge can be adjusted by panning, deducted. A manually operable solid bowl centrifuge can have a removable drum insert, which can be removed manually from the centrifuge drum together with the solid cake therein for emptying and cleaning.

Known solid bowl centrifuges have the disadvantage that a high proportion of liquid remains in the drum together with the solid which forms the also called filter cake solid cake, since the centrifugate can not run off completely over the overflow board or can be withdrawn with a Zentrifugatschälrohr. This residual liquid must then be disposed of either with the solid, whereby it is lost on the one hand and on the other hand to increased disposal quantities and disposal costs for the disposed wet solid leads, or it must be separated in a complex manner in another device to increase the degree of dryness of the solid from the solid. When removing the drum insert there is also the danger that the environment is polluted by spilling the liquid. Furthermore, it is disadvantageous that the operating personnel can come into contact with the liquid.

It is known, in particular, to manually scoop or dump the residual liquid left in the centrifuge drum after centrifuging. Again, there is a risk that the liquid is being dragged or the operator comes into contact with the liquid. Furthermore, this method is time consuming and also leads to large amounts of disposal, since the skimmed liquid does not have a sufficient degree of purity in order to continue to be used.

In the case of solid bowl centrifuges, there is therefore the problem of discharging the solid, which has been centrifuged out of a solid-liquid mixture and deposited on the centrifuge drum as a solid cake, as dry as possible out of the centrifuge after the cleaning process. If the discharged solid is very dry, this has the advantage that it can be used further and thus sold by the centrifuge user as a usable raw material. On the other hand, if the discharged solid is not adequately dried but contaminated with oil residues, it must be disposed of as hazardous waste at a high cost. Therefore, it is important to centrifuge the material to be centrifuged, a solid-liquid mixture, not only very well, ie, at high speed in the sedimentation operation to achieve high separation into solid components and liquid, but also it is important the solid is very good, that is dried at maximum speed of the drum before the solid cake is discharged from the drum. The problem is that modern, highly productive processing machines in production downtime immense costs cause. The fine abrasion (sludge) that occurs during mechanical cutting leads to high wear on tools. A renewal of the cooling lubricants by centrifuging is therefore essential.

Typical examples of solid-liquid mixtures which are cleaned with such centrifuges are all liquids used in industry, for example in metal, glass or ceramic processing. The liquids may therefore be oils, water, emulsions or other process liquids. The solids contained therein and separated in the centrifuge are very fine (for example, from grinding or erosion processes). Their size is in the range of a few microns to about 1 mm. For example, particles produced during grinding, honing or erosion are typically less than 20 μm.

The centrifuges to which the invention is directed are not primarily for the purpose of recovering the solid from the solid-liquid mixture (separation filtration), but the main purpose is to produce a liquid, i. to clean an oil or other emulsion contaminated with solid particles so that it can be reused (clarifying filtration). For this purpose, the solid must be centrifuged out of the contaminated liquid, but also it is important for the reasons described above that the solid is obtained as dry as possible.

A known solid bowl centrifuge, to which the invention relates, is usually open at the bottom, so that the solid can be discharged downwards or fall down. In the centrifuge drum is a peeling tube with which the cleaned or clarified liquid (the centrifugate), for example, an oil, an emulsion or other liquid, during the centrifuge carried out with the cleaning process (sedimentation) from the rotating drum discharged. This peeling tube is used in the present Application referred to as Zentrifugatschälrohr, but could also be referred to as a liquid peeling pipe or cleaning peeling pipe. The Zentrifugatschälrohr is usually fixed, that is arranged at a fixed radial distance from the drum, but may in principle be adjustable to different (radial) positions. The running drum is to be centrifuged solid-liquid mixture via an inlet, usually on the top fed. It is put in the same rotation as the drum. Due to the centrifugal force, a solid cake settles on the inner wall of the drum and in front of it, ie lying in the radial direction in front of the solid cake, forms a liquid column whose liquid level reaches to the Zentrifugatschälrohr and is permanently discharged through the Zentrifugatschälrohr.

When the solid cake has reached a certain layer thickness, the sedimentation operation of the centrifuge is stopped and the supply of solid-liquid mixture into the drum is stopped. The liquid column lying in front of the solids cake then receives no supply of liquid and thereby removes the positioned at the inner edge of the liquid column Zentrifugatschälrohr no further purified liquid. Subsequently, the drying of the solid cake in the centrifuge in a drying operation and then the removal of the solids cake from the centrifuge is initiated in a removal operation.

The centrifuging of the centrifuge drum supplied solid-liquid mixture in the sedimentation process is thus carried out at high speed of the centrifuge drum until a sufficiently thick layer of solids deposited on the inside of the centrifuge drum with the solids cake. The thickness of the solids cake that settles on the inside of the drum before it is discharged, for example by a paring knife, is typically about 2-3 cm. Thereafter, this layer is peeled off while the drum is running with a paring knife or scratched out. This raises the mentioned problem that the remaining in centrifuging in the solid cake liquid should be as far as possible removed from the solid cake before the solid is discharged from the centrifuge drum.

In the prior art, there are various solutions for a corresponding coolant treatment with cleaning centrifuges. In the publication DE 196 16 040 C2 a manually operable, not fully automatic operable solid bowl centrifuge has been proposed, which is a filter element for retaining solid cake forming solid, wherein the filter element, based on the axis of rotation of the centrifuge drum, is arranged in the axial direction of the solid cake and is designed so that it can be separated Contain solids and only the centrifugate passes, and a drainage channel which forms a flow path between the outlet side of the filter element and the surrounding centrifuge space, a drum lid for closing the centrifuge drum and a closing device for liquid-tight sealing of the discharge channel at its outlet-side discharge opening in the form of a sealing screw.

In order to be able to remove almost completely the residual liquid remaining in the centrifuge drum after centrifuging, the centrifuge is first stopped. At standstill, the closing device is opened manually, whereby the outlet side of the filter element is connected via the discharge channel forming a flow path with the centrifuge space surrounding the centrifuge drum and the drum cover. After opening the closing device, the centrifuge is then restarted manually, whereby the residual liquid is thrown through the filter element and the discharge channel into the centrifuge space, from which it can be withdrawn in a known manner. During the drying process, no additional liquid is supplied. After the final drying of the solid cake The centrifuge is stopped and the solids cake or the drum insert can be removed manually.

Although this known manually operable and not fully automatic centrifuge has the advantage that the solid cake can be dried at maximum speed of the drum. However, there is the problem that for complete drying of the solid cake, the centrifuge stopped, operated the seal screw and the centrifuge must then be restarted. This is associated with a manipulation and time. Furthermore, the centrifuging of the residual liquid into the centrifuge space surrounding the centrifuge drum and the drum lid is often undesirable.

According to a first method used in the prior art for preferably fully automatic discharge of the solids cake in a removal operation carried out following a sedimentation operation with a rotating scraper, the centrifuge drum is stopped after the sedimentation operation. The liquid from the centrifuge drum and the residual liquid from the solids cake run downwards when the centrifuge drum is stationary. With a scraping or scraper device, the solid cake is scraped off the drum wall. The disadvantage here is that the scraped solid has a very high liquid content, which may for example be up to 60% oil content, because the solid cake is not thrown dry in a drying operation. Furthermore, the wet solid may adhere to the scraper when scraping, so that the centrifuge drum must be rinsed several times before a new sedimentation operation is started. In addition, a displacement or diverting device arranged under the centrifuge drum is required in order to separate the rinsing liquid discharged downwardly in or after the removal operation from the solid also discharged downwards in the removal operation.

According to a second method used in the prior art for preferably fully automatic discharging of the solids cake in a removal operation carried out after a drying operation bores or openings are provided in the centrifuge lid, for example on the inner radius of the drum, through the sedimentation always a small proportion the liquid from the rotating drum runs uncleaned. After the sedimentation operation, the feed of solid-liquid mixture into the centrifuge is stopped for a drying operation and the residual liquid from the solids cake can be dried at maximum rotational speed of the centrifuge drum, the residual liquid passing through the bores or openings. Subsequently, the solid cake is scraped off in a removal operation. A disadvantage of this known type is that no optimal cleaning of the solid-liquid mixture or no optimal separation of the solid-liquid mixture is achieved in centrifugate and solid, as discharged with the expiring in sedimentation through the holes or holes liquid and solids become. Further, due to the permanent fluid flow, the holes or openings may become clogged by the solids entrained therein. This leads both to imbalances and to the fact that the solid cake can not be dried.

The most common solution known in the art uses spring-loaded centrifugal valves, such as ball valves, which open and close in response to the rotational speed of the drum to open or close a flow path for discharging the residual liquid from the solids cake. At high speed, ie in sedimentation mode, the valve is closed so that the liquid remains in the drum. At reduced speed, ie in a drying operation, the valve opens because of the reduced centrifugal force, and the remaining liquid contained in the solids cake, ie liquid that has not already been withdrawn from the Zentrifugatschälrohr, can drain through a released from the valve opening from the drum. In the sedimentation operation, therefore, the liquid is withdrawn through the Zentrifugatschälrohr, and as soon as a thick solid cake has formed, the rotational speed of the drum for the drying operation is reduced to a smaller value.

As a result, arranged on the drum wall, spring-loaded, controlled by the centrifugal force valves open and contained in the solids cake residual liquid can drain through the valves at a lower speed of the drum. Following this, the solid cake is then peeled out in a removal operation at the same or even further reduced drum speed. When peeling the solid with the paring knife from the inner wall of the drum, the solid is scraped off the drum wall with a scraper and falls down through an opening in the drum into a collection container. Subsequently, the sedimentation operation can be resumed. For this purpose, the speed of the drum is increased so far that close the centrifugal valves, solid-liquid mixture is fed, the solid cake grows again and purified liquid is withdrawn through the Zentrifugatschälrohr.

This known embodiment has the following disadvantages: First, the valves do not open at high, but only at greatly reduced speed. This has the consequence that the solids cake is not optimally dried at high speed, but only at low speed of the residual liquid contained in it. He therefore still has a relatively high moisture content, which is disadvantageous for the reasons described above. On the other hand, depending on the type of solids separated from the solid-liquid mixture in the solids cake, the valves can clog or stick. Therefore, usually at a rotational speed of the drum, which is opposite to the maximum speed used in the cleaning process is reduced, that is, when the valves are opened, the drum and the solid cake again rinsing liquid supplied to clean the valve seat and the channels. This additional flushing fluid must be recycled or treated. Nevertheless, the clogging or sticking of the valves allows liquids to escape through the valves during the cleaning process and must be collected separately. In some cases, even a remission lid must be opened and the valve seat manually cleaned or rinsed to service the centrifuge. In addition, the valves must be set in a complex series of tests and occasionally readjusted. Basically, it is disadvantageous in this embodiment that the cleaning and drying process solids can get into the valves and sealing surfaces, the system is very susceptible to interference and the solid is dried only at low speed.

In the prior art, various centrifuges are known with horizontal axis of rotation. These generally have the disadvantage that the discharge of the deposited solid cake is difficult.

In the DE 36 34 994 A1 is a Vollmantelzentrifuge horizontal axis of rotation and a cylindrical centrifuge drum with closed drum bottom described which has no Zentrifugatschälrohr. The connection openings formed in the drum cover, which form a fluid channel from the inside of the centrifuge drum, are not arranged at the largest internal diameter of the drum, so that complete drying of the solids cake is not possible. The manner of solids discharge from the centrifuge drum is unclear.

In the DE 36 26 314 A1 a centrifuge with a horizontal axis of rotation and a cylindrical centrifuge drum with an open drum bottom is described, which has no arranged inside the centrifuge drum Zentrifugatschälrohr. The centrifuge drum is a Combination of sieve and solid drum and has essentially the function of a basket drum. The manner of solids discharge from the centrifuge drum is unclear.

In the DE 41 32 044 C1 is described a Vollmantelzentrifuge with horizontal axis of rotation and a cylindrical centrifuge drum having no Zentrifugatschälrohr. The connection openings formed in the drum cover, which form a fluid channel from the inside of the centrifuge drum, are not arranged at the largest internal diameter of the drum, so that complete drying of the solids cake is not possible. The manner of solids discharge from the centrifuge drum is unclear.

In the DE 26 03 610 A1 a Siebmantelzentrifuge with horizontal axis of rotation and a cylindrical centrifuge drum is described, which has no Zentrifugatschälrohr. The manner of solids discharge from the centrifuge drum is unclear.

In the DE 10 2008 009 253 A1 describes a Siebmantelzentrifuge with vertical axis of rotation and a cylindrical centrifuge drum having no Zentrifugatschälrohr. The solids discharge takes place in a complicated manner by means of scraper devices fastened to the drum cover.

Based on this prior art, the present invention seeks to provide a vertical Vollmantelzentrifuge, with the deposited in a sedimentation solid cake in a drying operation at high speed can be maximally dried before (at low speed) in a sampling operation with a Paring knife is scraped out. The solid should be as dry as possible, ie discharged in the removal operation, to Disposal costs for its disposal or to be able to continue using it as a valuable raw material.

This object is achieved by a solid bowl centrifuge with the features of the attached claim 1. Preferred embodiments, developments and uses of the invention will become apparent from the independent and dependent claims and the following description with accompanying drawings.

A full-bowl centrifuge according to the invention, in particular for sedimentation, for separating solid-liquid mixtures into centrifugate and a solids cake comprising a rotatable about a vertical axis of rotation, downwardly open solid bowl centrifuge drum, a drum lid for closing the centrifuge drum, and a in the centrifuge drum arranged Zentrifugatschälrohr for withdrawing the centrifugate from the rotating centrifuge drum during a sedimentation carried out with the centrifuge, thus has the peculiarity that it comprises an annular peeling chamber, which is arranged axially above the drum cover, it has formed in the drum cover connecting openings which a fluid channel form liquid or residual liquid from a deposited on the inside of the centrifuge drum solids cake to the peeling chamber, and they are arranged in the peeling chamber Restflüssigkeitsschälrohr for Extracting liquid or residual liquid from the peeling chamber, wherein the Restflüssigkeitsschälrohr is designed such that it can be activated during a drying operation, so that in the drying operation with the Restflüssigkeitsschälrohr liquid or residual liquid from the peeling chamber is removable.

A corresponding inventive method for separating solid-liquid mixtures in centrifugate and a solid cake, in particular a method of sedimentation, by means of a Vollmantelzentrifuge, the A downwardly open solid bowl centrifuge drum rotatable about a vertical axis of rotation, a drum lid for closing the centrifuge drum, and a centrifuge peeler tube disposed in the centrifuge drum for withdrawing the centrifuge from the rotating centrifuge drum during a sedimentation operation performed with the centrifuge has the corresponding feature in that for centrifuging the solid-liquid mixture a centrifuge is used which comprises an annular peeling chamber arranged axially above the drum cover, which has connecting openings formed in the drum cover which provide a liquid or residual liquid passageway for fluid on the inside of the drum Centrifuge drum deposited solids cake to the peeling chamber, and which comprises a arranged in the peeling chamber residual liquid peeling pipe for removing liquid or residual liquid from the peeling chamber, w obei drying of the sedimentation on the inside of the centrifuge drum deposited solid cake during a drying operation, the supply of solid-liquid mixture is interrupted in the centrifuge drum and the Restflüssigkeitsschälrohr is activated, so that in the drying operation with the Restflüssigkeitsschälrohr liquid or residual liquid is withdrawn from the peeling chamber. The process can be carried out manually, partially, semi or fully automatically controlled.

The present invention thus improves the properties of the previously known solid bowl centrifuges of the type mentioned above by an annular peeling chamber and a Restflüssigkeitsschälrohr formed in addition to the Zentrifugatschälrohr, which is arranged in the peeling chamber and for withdrawing liquid or residual liquid from the peeling chamber from the solid cake passes through formed in the drum cover connecting openings in the peeling chamber, at maximum speed of the drum is used.

The invention is based on the finding that it is possible with these characteristics Vollmantelzentrifugen to dry the solid cake at very high speed maximum before it is discharged from the drum, since in the drying operation, the liquid or residual liquid from the solid cake at a very high speed pass through the connection openings in the peeling chamber and can be removed there with the Restflüssigkeitsschälrohr.

The advantages of inventive solid bowl centrifuges thus consist in that the solid cake at very high speed of the drum, which corresponds to the maximum speed used in sedimentation, can be dried and optimum cleaning performance is achieved. Ecology and economy complement each other. High disposal costs for the solid cake are avoided, instead it can be recycled, and also by the effective cleaning of the solid-liquid mixture, a cost reduction is achieved. Centrifuges according to the invention ensure the optimum state of the cleaned liquids, for example of lubricants, whereby with the centrifuge both the separation of liquid, e.g. Oil, as well as the separation of solids from a solid-liquid mixture, such as an emulsion, is possible. The dried solid at maximum speed can be recycled or disposed of with the resulting in a production residues such as chips while avoiding the expense of hazardous waste.

• Der Feststoff wird optimal bis auf eine geringe Restfeuchte getrocknet, bevor er aus der Zentrifugentrommel ausgetragen wird, da die in ihm enthaltene Restflüssigkeit bei maximaler Drehzahl der Zentrifugentrommel abgezogen werden kann.
• Dadurch ergeben sich beste Bedingungen, um den Feststoff weiter verwerten zu können oder um hohe Entsorgungskosten zu vermeiden.
• Es wird eine optimale Trennung des Fest-Flüssig-Gemischs in geklärtes Zentrifugat und Feststoff erzielt.
• Es sind keine (beweglichen) Ventilelemente vorhanden, die verstopfen oder verkleben können, daher ist der Betrieb der erfindungsgemäßen Zentrifuge sehr störungsfrei.
• Es wird keine Spülflüssigkeit für das Reinigen von Ventilsitzen oder Kanälen benötigt. Es wird also (im Sedimentationsbetrieb) eine volle, optimale Reinigungsleistung beim Betrieb der Zentrifuge und beim Reinigen von Fest-Flüssig-Gemisch erzielt.
• Die Zentrifugentrommel muss vor, während oder nach dem Austragen des Feststoffkuchens nicht gespült werden, um das Verstopfen oder Verkleben von Ventilen zu vermeiden. Dadurch ist die gesamte Zeitdauer, die zum Austragen des Feststoffs erforderlich ist, geringer und die Zentrifuge kann früher wieder in dem Reinigungsprozess verwendet werden.
• Die Zentrifuge ist einfach und kostengünstig herstellbar sowie leicht bedienbar, wobei einzelne, mehrere oder alle Schritte (Sedimentationsbetrieb, Trocknungsbetrieb und Entnahmebetrieb) manuell, teil-, halb- oder vollautomatisch steuerbar sein können. Besonders vorteilhaft ist, dass eine erfindungsgemäße Zentrifuge vollautomatisch betreibbar ist.
• Der gesamte Prozess, d.h. Sedimentationsbetrieb, Trocknungsbetrieb und Entnahmebetrieb, kann mit einer einzigen Zentrifuge durchgeführt werden, auch teil-, halb- oder vollautomatisch.
• Die Zentrifuge kann derart ausgebildet werden, dass das Bedienungspersonal nicht mit der Restflüssigkeit in Kontakt kommt und diese nicht abgeschöpft oder in einer separaten Trennvorrichtung abgetrennt werden muss.

The invention thus has the following advantages over the prior art:

• The solid is optimally dried to a low residual moisture before it is discharged from the centrifuge drum, since the residual liquid contained in it can be withdrawn at maximum speed of the centrifuge drum.
• This results in the best conditions for further recycling of the solid or to avoid high disposal costs.
• It is achieved an optimal separation of the solid-liquid mixture in clarified centrifugate and solid.
• There are no (movable) valve elements that can clog or stick, therefore, the operation of the centrifuge according to the invention is very trouble-free.
• No flushing liquid is required for cleaning valve seats or channels. It is thus achieved (in sedimentation) a full, optimal cleaning performance during operation of the centrifuge and cleaning of solid-liquid mixture.
• The centrifuge drum must not be rinsed before, during or after discharge of the solids cake to avoid clogging or sticking of valves. As a result, the total time required to discharge the solid is lower and the centrifuge can be reused earlier in the cleaning process.
• The centrifuge is simple and inexpensive to produce and easy to use, with individual, several or all steps (sedimentation, drying operation and removal operation) can be manually, partially, semi or fully automatically controlled. It is particularly advantageous that a centrifuge according to the invention is fully automatic operable.
• The entire process, ie sedimentation operation, drying operation and withdrawal operation, can be carried out with a single centrifuge, also semi-automatic, semi-automatic or fully automatic.
• The centrifuge can be designed such that the operating personnel does not come into contact with the residual liquid and this does not have to be skimmed off or separated in a separate separating device.

The residual liquid peeling pipe can in principle also be designed such that during the sedimentation operation, i. simultaneously or instead of Zentrifugatschälrohrs, clarified with him clarified centrifugate or residual liquid can be withdrawn from the peeling chamber, so it can be activated not only for the drying operation, but also during the sedimentation. According to a preferred development, however, it is provided that the residual liquid peeling pipe can be deactivated during the sedimentation operation, so that no liquid or residual liquid can be withdrawn from the peeling chamber in the sedimentation operation with the residual liquid peeling pipe. This simplifies the expenditure on equipment, e.g. on valves and control devices, for operating the centrifuge. Furthermore, the Zentrifugatschälrohr usually also allows due to a larger diameter of its flow cross-sections a larger volume flow than the Restflüssigkeitsschälrohr, so that the Zentrifugatschälrohr is usually not waived. In exceptional cases, however, could also be dispensed with the Zentrifugatschälrohr; In this case, the claimed, arranged in the centrifuge drum Zentrifugatschälrohr coincides with the invention, arranged in the peeling chamber Restflüssigkeitsschälrohr.

To activate and deactivate the Restflüssigkeitsschälrohrs for the removal of clarified centrifugate or residual liquid from the peeling chamber may be suitably provided that the inlet opening of the Restflüssigkeitsschälrohrs or the Restflüssigkeitsschälrohr in the active position in liquid or residual liquid, which is located in the peeling chamber, immersed or retractable is, and in the inactive position of liquid or residual liquid, which is located in the peeling chamber, is extendable. For this purpose, the residual liquid peeling pipe can be, for example, pivotable or linearly movable.

Thus, in the drying operation, the residual liquid from the peeling chamber can be removed as completely as possible, it is advantageous if the inlet opening of the Restflüssigkeitsschälrohrs or the Restflüssigkeitsschälrohr in the active position relative to the axis of rotation of the centrifuge drum is moved to a diameter which is at least the largest relative to the axis of rotation Outside diameter of the solid cake corresponds. If the centrifuge drum does not have a drum insert, the outer edge of the solids cake is identical to the inner wall of the centrifuge drum. In an inserted drum insert, the outer edge of the solids cake is the inner wall of the drum insert. The liquid located between the radially outermost position of the inlet opening of the residual liquid peeling pipe and the outermost edge of the solid cake could not be drawn off through the residual liquid peeling pipe, if the residual liquid peeling pipe does not extend to the outer edge of the solids cake. For the widest possible drying of the waste cake, it is therefore advantageous if the residual liquid peeling pipe can be moved until then or beyond.

In order to be able to deactivate the residual liquid peeling pipe in the sedimentation operation, it can advantageously be provided that the inlet opening of the residual liquid peeling pipe or the residual liquid peeling pipe can be moved to a diameter in the inactive position relative to the axis of rotation of the centrifuge drum, which diameter is smaller than the inner diameter of the centrifuge drum Liquid column in the centrifuge drum is, wherein the inner diameter of the liquid column is predetermined in the centrifuge drum by the position of the inlet opening of Zentrifugatschälrohrs in sedimentation.

In order to avoid, by means of a simple structural measure, that during sedimentation operation, even when the residual liquid peeling pipe is deactivated, ie if the residual liquid peeling pipe is not immersed in the liquid in the peeling chamber, yet liquid is withdrawn from the peeling chamber, namely by overflow of liquid over the upper end of the peeling chamber, it can be provided that the peeling chamber has an annular, axially upwardly closing the peeling chamber Peeling chamber having a smaller inner diameter than the inner diameter of the liquid column in the centrifuge drum, which is determined by the position of the inlet opening of Zentrifugatschälrohrs in sedimentation. In other words, the inner diameter of the peeling chamber cover, that is, the outer diameter of a central opening in the peeling chamber cover, is smaller than the inner diameter of the liquid column of the running centrifuge drum, which is determined by the position of the usually fixed Zentrifugatschälrohrs in the centrifuge drum. Characterized the liquid column is covered in the centrifuge drum and in the peeling chamber with rotating centrifuge drum up from the peeling chamber cover and does not reach the more inner edge of the central opening in the peeling chamber cover so that they can not overflow over this edge.

Thus, in the drying operation, the residual liquid from the peeling chamber can be removed as completely as possible, it is also advantageous if the relation to the axis of rotation of the centrifuge drum outer edge of the peeling chamber extends to a diameter which is at least the largest relative to the axis of rotation of the centrifuge drum outside Diameter of the solid cake corresponds.

For the same reason, it can advantageously be provided that the centrifuge has connecting openings formed in the drum cover, which have a fluid channel for liquid or residual liquid from a solid cake deposited on the inside of the centrifuge drum form the peeling chamber and which are formed in relation to the axis of rotation of the centrifuge drum in the radial direction outside in the drum lid at a diameter corresponding to the largest outside diameter of the solids cake relative to the axis of rotation of the centrifuge drum. In other words, the connection openings are arranged on the outside of the centrifuge drum, ie the largest drum diameter, in order to ensure that the residual liquid emerges as completely as possible into the peeling chamber and can be removed therefrom by means of the residual liquid peeling tube.

In addition to the connection openings at the largest inner diameter of the drum, one or more bores may be provided which are arranged at smaller diameters in order to accelerate the outflow of the liquid column from the centrifuge drum through the connection openings and the bores into the peeling chamber. The larger the total area of the connection openings, the faster the residual liquid can pass. Therefore, it is proposed according to an additional advantageous feature that the drum cover has one or more connecting openings, which are formed at least partially annular or arcuate. By an arcuate extent in the direction of rotation of the centrifuge drum of the available cross section is increased.

In particular embodiments, or when centrifuging special solid-liquid mixtures, the connection openings in the drum cover may have filter elements designed to retain the solid to be separated and allow only the liquid to pass to allow coarse solid to pass from the filter cake into the peeling chamber to prevent. In general, however, such filter elements are not required.

According to a further advantageous aspect, which may have independent significance both in combination with the invention described above and independently thereof, a Vollmantelzentrifuge, in particular for sedimentation, for separating solid-liquid mixtures in clarified centrifugate and a solid cake is proposed which a downwardly open solid bowl centrifuge drum rotatable about a vertical axis of rotation, a drum lid for closing the centrifuge drum, and a centrifuge peeler tube disposed in the centrifuge drum for drawing the clarified centrifugate out of the rotating centrifuge drum during a sedimentation operation performed with the centrifuge; that it has a paring knife for discharging the deposited in the centrifuge drum solids cake, which does not rotate with the centrifuge drum during sedimentation, but in the direction of rotation of Zentri Fugentrommel is fixed, and which is designed such that it can be retracted for scraping the solid cake in a removal operation by means of a paring knife drive from the axially down side of the centrifuge drum along the inner wall of the drum in the centrifuge drum. This scraping could also be referred to as scraping or peeling. The scraping or the entire removal operation can be carried out manually, partially, semi or fully automatically controlled.

A running peeling knife known from the prior art rotates with the centrifuge drum during the sedimentation operation, without there being any relative movement between the peeling blade and the drum wall. To scrape the solids cake, the paring knife then moves relative to the drum wall or the drum wall relative to the paring knife, wherein the solid is scraped out. This residue of the solid can get stuck on the paring knife and lead to imbalance in the subsequent cleaning process, ie at high speed of the drum. In this case, usually the drum must again be rinsed and / or scraped. In a solid bowl centrifuge, in particular a centrifuge according to the invention, a peeling knife, which is fixed relative to the direction of rotation of the centrifuge drum and is not co-rotating with the centrifuge drum, is advantageously used.

In principle, any drum shape can be used, for example a cylindrical, curved or with different angles successive rectilinear sections provided centrifuge drum when the paring knife has a suitable corresponding feed or path control. However, to reduce the expenditure on equipment, it is advantageous if the drum inner wall is frusto-conical, at least in a region along which by the peeling knife Feststoffkuchen is ausschabbar, and the peeling knife drive as a linear drive for moving or advancing the peeling knife along a rectilinear path parallel to the drum inner wall is trained. This embodiment is optimal in terms of both manufacturing costs and solids discharge, since no corners, edges and pockets can be left in which solids remain, which can lead to imbalances.

Figur 1

einen Gesamtschnitt einer erfindungsgemäßen Vollmantelzentrifuge mit einem Schälmesser,

Figur 2

einen Teilschnitt durch die Zentrifuge von Figur 1 im Sedimentationsbetrieb mit Trommel und Antriebsmotor für die Trommel,

Figur 3

den Teilschnitt von Figur 2 im Trocknungsbetrieb,

Figur 4

den Teilschnitt von Figur 2 im Entnahmebetrieb und

Figur 5

eine Draufsicht auf die Zentrifuge von Figur 1 mit dem Restflüssigkeitsschälrohr in den beiden Endstellungen.

The invention will be explained in more detail with reference to an embodiment shown in FIGS. The features described therein may be used alone or in combination with each other to provide preferred embodiments of the invention. Identical or equivalent parts are denoted by the same reference numerals in the various figures and usually described only once, although they can be used advantageously in other embodiments. Show it:

FIG. 1

an overall section of a solid bowl centrifuge according to the invention with a paring knife,

FIG. 2

a partial section through the centrifuge of FIG. 1 in sedimentation mode with drum and drive motor for the drum,

FIG. 3

the partial section of FIG. 2 in drying operation,

FIG. 4

the partial section of FIG. 2 in the removal operation and

FIG. 5

a plan view of the centrifuge of FIG. 1 with the Restflüssigkeitsschälrohr in the two end positions.

The FIG. 1 shows an overall section of an embodiment of a solid bowl centrifuge 1 according to the invention for the fully automatic separation of solid-liquid mixtures in clarified centrifugate 2 and a solid cake 3, in particular for sedimentation. It comprises a solid-bowl centrifuge drum 5 rotatable about a rotation axis 4, a drum cover 6 for closing the centrifuge drum 5, and a centrifugal peeling tube 7 arranged in the centrifuge drum for drawing the clarified centrifugate 2 out of the rotating centrifuge drum 5 during a sedimentation operation performed with the centrifuge 1.

The drum cover 6 is connected by means of fastening elements 8 with the centrifuge drum 5. Furthermore, an unrepresented safety bolt can be provided which prevents rotation of the drum cover 6 relative to the centrifuge drum 5. The centrifuge 1 is surrounded by a housing 9, which can be closed by a machine cover 10, which is mounted with machine cover fixtures 11.

The centrifuge drum 5 is mounted on the drum cover 6 in a bearing 12 and is rotated by means of a motor 13 or geared motor and a transmission belt 14 in rotation about the vertical axis of rotation 4. In modified embodiments, the drive motor 13 can also be integrated directly into the bearing 12 or arranged along the axis of rotation 4. The centrifuge drum 5 is open at the bottom, so has no or a downwardly open drum bottom. The centrifuge drum 5 may have any shape, i. For example, have a cylindrical, curved or with different angles successive rectilinear sections provided inner wall. The illustrated embodiment shows a preferred embodiment with a frusto-conical centrifuge drum 5 or drum inner wall, which forms a downwardly narrowing cone.

In general, the centrifuge drum 5 will have a shape tapering downwards in the axial direction in any way, because then a solid cake 3 settles on the inner wall of the centrifuge drum 5 due to the centrifugal force and lies in front of the solids cake 3 in the radial direction, can form a liquid column in the sedimentation, the liquid level extends to Zentrifugatschälrohr 7 and permanently withdrawn through the Zentrifugatschälrohr 7 from the rotating centrifuge drum. In other words, the downwardly tapering shape of the centrifuge drum 5 results as a result of the requirement that the withdrawal of liquid through the Zentrifugatschälrohr 7 from a radially further inward position than the position of the deposited solid cake 3 should lie. Since the residual liquid is withdrawn from the solids cake 3 via the drum cover 6, the inlet opening of the Zentrifugatschälrohrs 7 is preferably arranged in the region of the axially lower end of the centrifuge drum 5, so that the solid cake 3 in the axially overlying area of the widening upward drum inner wall can.

The filling of the centrifuge drum 5 with solid-liquid mixture via an unillustrated filling tube, usually on the top of the centrifuge drum 5 or in some embodiments from below into the centrifuge drum 5. Inside the centrifuge drum 5 are acceleration plates 15 for distributing the Solid-liquid mixture arranged. The solid-liquid mixture to be centrifuged is fed to the running centrifuge drum 5 via an inlet, usually via the top, usually continuously. It is set in the centrifuge drum 5 in rotation. The specific heavier solids settle in a solid cake 3 on the drum wall.

In the illustrated example case, the drum wall, on which the solid cake 3 deposits in the sedimentation mode, is formed by the solid bowl centrifuge drum 5. In other embodiments, a drum insert, which consists for example of rubber and is removable by means of insert handles, be inserted into the centrifuge drum 5, wherein the inner wall forms the drum wall, where the solid cake 3 deposits.

Before the solid cake 3, ie lying radially in front of the solid cake 3, a liquid column whose inner liquid level 16 to, based on the axis of rotation 4 of the centrifuge drum 5, largest diameter of a Zentrifugatschälrohrs 7 extends and with the Zentrifugatschälrohr 7, usually continuously, as clarified centrifugate 2 is discharged. In the sedimentation operation, the clarified centrifugate 2 is withdrawn via the Zentrifugatschälrohr 7. The Zentrifugatschälrohr 7 is generally fixed, that is arranged at a fixed radial distance from the drum inner wall or the axis of rotation 4 of the centrifuge drum 5, but can in principle also be adjustable to different (radial) positions.

Axially above the drum cover 6, an annular peeling chamber 17 is arranged. The diameter of the peeling chamber 17 is greater than its height. It is thus designed annular and could also be referred to as a peeling ring. The lower end of the peeling chamber 17 is formed by the drum cover 6, the upper end of a peeling chamber cover 18. The peeling chamber cover 18 is connected to the drum cover 6 or to the centrifuge drum 5 by means of the fastening elements 8.

In the drum cover 6 there are connecting openings 19, which serve as a fluid channel for liquid or residual liquid 27 from a deposited on the inside of the centrifuge drum 5 solid cake 3 to the peeling chamber 17. The connection openings 19 are located on the outside of the centrifuge drum 5, i. arranged at the largest inner diameter drum to ensure that the residual liquid 27 can emerge from the solid cake 3 as completely as possible in the peeling chamber 17. In addition to the connection openings 19 at the largest inner diameter of the drum, further bores 20 are provided radially further inwards in order to allow a faster outflow of the liquid column from the centrifuge drum 5 through the connection openings 19 and the bores 20 into the peeling chamber 17.

The peeling chamber 17 thus forms an annular collecting pocket or an annular collecting space for liquid or residual liquid 27 emerging from the solids cake 3 through the connecting openings 19 in the drum cover 6 in the sedimentation mode and in particular in the drying operation.

In the peeling chamber 17, a residual liquid peeling pipe 21 is arranged, which serves for drawing off liquid or residual liquid 27 from the peeling chamber 17. The residual liquid peeling pipe 21 is formed such that it can be activated during a drying operation, so that in Drying operation with the residual liquid peeling pipe 21 liquid or residual liquid 27 from the peeling chamber 17 is removable. For activating the residual liquid peeling pipe 21 for withdrawing liquid (centrifugate) or residual liquid 27 from the peeling chamber 17, in particular in the drying operation, the inlet opening of the residual liquid peeling pipe 21 can be in the active position in liquid or residual liquid 27, which is located in the peeling chamber 17, be dipped or retracted. In the inactive position, in particular in the sedimentation operation, it can be swung out or extended from liquid or residual liquid 27, which is located in the peeling chamber 17.

For this purpose, the Restflüssigkeitsschälrohr 21, for example, be pivotable or linearly movable. The embodiment shows a Restflüssigkeitsschälrohr 21 which is pivotable about a parallel to the axis of rotation 4 of the centrifuge drum 5 extending pivot axis. The Restflüssigkeitsschälrohr 21 may be integrally formed in order to achieve optimum tightness or to allow easy production without individual parts sealing gaskets with each other.

In the FIG. 1 is the Restflüssigkeitsschälrohr 21 in the pivoted position during drying of the solid cake in the drying operation. In the normal cleaning process, ie in the sedimentation, while purified by the centrifuge 1 running solid-liquid mixture and the purified liquid 2 is withdrawn from the Zentrifugatschälrohr 7, the Restflüssigkeitsschälrohr 21 is not active, ie pivoted out of the liquid column in the peeling chamber 17 or moved out.

For drying the solid cake 3, the supply of solid-liquid mixture is stopped in the centrifuge 1, the Restflüssigkeitsschälrohr 21 pivoted into the liquid in the peeling chamber 17 and the liquid contained in the peeling chamber 17 is with the Restflüssigkeitsschälrohr 21 deducted. If it is desired to avoid heavy impurities or strong spraying, while the speed of the centrifuge drum 5 can also be reduced. Important for achieving a high degree of drying of the solid cake 3, however, is that at the end of stripping the residual liquid 27 by means of the Restflüssigkeitsschälrohrs 21 from the peeling chamber 17, the speed of the drum 5 is raised again to a high or maximum value, so that the solid cake 3 at maximum speed dried and the liquid contained in the solid cake 3 at the highest possible maximum speed by means of the Restflüssigkeitsschälrohrs 21 from the peeling chamber 17 is removed.

Accordingly, it is advantageously provided in a centrifuge 1 according to the invention that the residual liquid peeling tube 21 can be activated at a high rotational speed of the centrifuge drum 5, which corresponds essentially to the maximum rotational speed of the centrifuge drum 5 used in the sedimentation mode for withdrawing liquid or residual liquid 27 from the peeling chamber 17 , As a result, the residual liquid 27 can be withdrawn from the solids cake 3 via the peeling chamber 17, wherein the withdrawn residual liquid 27 can have a high degree of purity with a reduced solids content which corresponds to that of the centrifugate 2 withdrawn in sedimentation operation. In a corresponding method, it is proposed that the residual liquid peeling pipe 21 be activated at a high rotational speed of the centrifuge drum 5, which corresponds essentially to the maximum rotational speed of the centrifuge drum 5 used in the sedimentation operation for drawing off liquid or residual liquid 27 from the peeling chamber 17.

The duration of the drying time during which the Restflüssigkeitsschälrohr 21 is active, that is dipped or retracted in the drying operation in residual liquid 27 in the peeling chamber 17, the respective liquids and solids adjusted. Typical times are between two and five minutes.

After removing the residual liquid 27 from the peeling chamber 17 with the Restflüssigkeitsschälrohr 21 in the drying operation, the solid cake 3 is scraped with a paring knife 23 before resuming the sedimentation first in the removal operation. This is usually done at reduced speed of the centrifuge drum 5. Such a paring knife 23, for example, pneumatically, electrically or hydraulically driven into the centrifuge drum 5. The propulsion of the peeling blade 23 is usually linear. The scraped, optimally dried solid falls down from the downwardly open centrifuge drum 5 and is collected. Thereafter, the cleaning process in sedimentation operation can start from the beginning, i. the centrifuge drum 5 is driven to maximum speed and new, solid-liquid mixture to be cleaned is fed to the centrifuge drum 5 and centrifuged.

The illustrated centrifuge 1 has a paring knife 23 for discharging the deposited in the centrifuge drum 5 solid cake 3, which does not rotate with the centrifuge drum 5 during sedimentation, but is fixed in the direction of rotation of the centrifuge drum 5. It is designed in such a way that it can be moved into the centrifuge drum 5 from the axially lower side of the centrifuge drum 5 along the inside wall of the drum for scraping out the solid cake 3 in a removal operation by means of a peeling knife drive 24. Since the drum inner wall is formed frusto-conical, at least in a region along which by means of the peeling knife 23 solids cake 3 is ausschabbar, the peeling blade drive 24 is formed as a linear drive for moving or delivering the peeling blade 23 along a rectilinear path parallel to the drum inner wall.

Following the drying operation, therefore, solid cake 3 deposited on the inside of the centrifuge drum 5 is discharged from the centrifuge drum 5 in a removal operation with a peeling blade 23 which does not rotate with the centrifuge drum 5 during the sedimentation operation, but is stationary in the direction of rotation 28 of the centrifuge drum 5, and is moved to the scraping of the solid cake 3 in the removal operation by means of a paring knife drive 24 from the axially lower side of the centrifuge drum 5 along the inner wall of the drum in the centrifuge drum 5. The peeling of the solid cake 3 with the peeling blade 23 from the centrifuge drum 5 is advantageously carried out at a reduced rotational speed of the centrifuge drum 5.

The FIGS. 2 to 4 show individual steps in the operation of the centrifuge 1 according to FIG. 1 , The FIG. 2 shows the sedimentation, in which the Restflüssigkeitsschälrohr 21 is in the non-active position, that is pivoted out of the liquid column in the peeling chamber 17. The FIG. 3 shows accordingly FIG. 1 the drying operation in which the Restflüssigkeitsschälrohr 21 is in the active position, that is pivoted into the liquid column in the peeling chamber 17 in order to deduct the residual liquid 27 can. The FIG. 4 shows the removal operation for discharging the solid cake 3 from the centrifuge drum 5, wherein the peeling blade 23 is fully retracted into the centrifuge drum 5.

The FIG. 5 shows a plan view of the centrifuge 1 of FIG. 1 with the Restflüssigkeitsschälrohr 21 in the two end positions, ie in the active position 25 in the drying operation and in the inactive position 26 in sedimentation. The residual liquid peeling pipe 21 is shown here as a pivotable variant. It is a bent tube whose inlet opening 22 is directed counter to the direction of rotation 28 of the rotating centrifuge drum 5. The inlet opening 22 of the residual liquid peeling pipe 21, as well as that of Zentrifugatschälrohrs 7, preferably opposite to the direction of rotation 28 of the centrifuge drum 5, to allow optimum "peeling" of the liquid column at the inner edge of the liquid column.

LIST OF REFERENCE NUMBERS

1

Solid bowl centrifuge

2

clarified centrifugate

3

Solid cake

4

axis of rotation

5

centrifuge drum

6

drum lid

7

Zentrifugatschälrohr

8th

fastener

9

casing

10

Generator cover

11

Generator cover mounting

12

camp

13

engine

14

transmission belt

15

acceleration block

16

liquid Level

17

peeling chamber

18

Peeling chamber lid

19

connecting opening

20

drilling

21

Residual liquid outlet pipe

22

inlet opening

23

paring knife

24

Paring knife drive

25

active position

26

inactive position

27

residual liquid

28

direction of rotation

Claims (15)

A solid bowl centrifuge (1), in particular for sedimentation, for separating solid-liquid mixtures into clarified centrifugate (2) and a solid cake (3), comprising a solid bowl centrifuge drum (5) rotatable about a vertical axis of rotation (4) ), a drum lid (6) for closing the centrifuge drum (5), and a Zentrifugatschälrohr (7) arranged in the centrifuge drum (5) for withdrawing the centrifugate (2) from the rotating centrifuge drum (5) during a centrifuge (1) carried out sedimentation operation,
characterized in that
it comprises an annular peeling chamber (17) arranged axially above the drum cover (6),
in the drum cover (6) formed connecting openings (19) which form a fluid channel for liquid or residual liquid (27) from a on the inside of the centrifuge drum (5) deposited solid cake (3) to the peeling chamber (17), and
it comprises a residual liquid peeling pipe (21) arranged in the peeling chamber (17) for drawing off liquid or residual liquid (27) from the peeling chamber (17), wherein
the Restflüssigkeitsschälrohr (21) is designed such that it can be activated during a drying operation, so that in the drying operation with the Restflüssigkeitsschälrohr (21) liquid or residual liquid (27) from the peeling chamber (17) is removable. Centrifuge (1) according to Claim 1, characterized in that the residual liquid peeling pipe (21) can be deactivated during the sedimentation operation so that no liquid or residual liquid (27) can be withdrawn from the peeling chamber (17) in the sedimentation operation with the residual liquid peeling pipe (21). Centrifuge (1) according to one of the preceding claims, characterized in that the residual liquid peeling pipe (21) at a high rotational speed of the centrifuge drum (5), which corresponds substantially to the maximum rotational speed of the centrifuge drum (5) used in the sedimentation operation, for drawing off liquid or residual liquid (27) from the peeling chamber (17) can be activated. Centrifuge (1) according to one of the preceding claims, characterized in that the inlet opening (22) of the residual liquid peeling pipe (21) or the residual liquid peeling pipe (21) in the active position in liquid or residual liquid (27), which is located in the peeling chamber (17). is, submersible or retractable, and in the inactive position of liquid or residual liquid (27), which is located in the peeling chamber (17), is extendable. Centrifuge (1) according to the preceding claim, characterized in that the inlet opening (22) of the Restflüssigkeitsschälrohrs (21) or the Restflüssigkeitsschälrohr (21) in the active position relative to the axis of rotation (4) of the centrifuge drum (5) is movable to a diameter which corresponds at least to the largest outside diameter of the solid cake (3) relative to the axis of rotation (4). Centrifuge (1) according to claim 4 or 5, characterized in that the inlet opening (22) of the residual liquid peeling pipe (21) or the residual liquid peeling pipe (21) in the inactive position relative to the axis of rotation (4) of the centrifuge drum (5) is movable to a diameter which is smaller than the inner diameter of the liquid column in the centrifuge drum (5) relative to the axis of rotation (4) of the centrifuge drum (5), wherein the inner diameter of the liquid column in the centrifuge drum (5) is predetermined by the position of the inlet opening of Zentrifugatschälrohrs (7) in sedimentation. Centrifuge (1) according to one of the preceding claims, characterized in that the peeling chamber (17) has a peeling chamber (17) axially upwardly closing, annular peeling chamber cover (18) having a smaller inner diameter than the inner diameter of the liquid column in the centrifuge drum ( 5), which is predetermined by the position of the inlet opening of Zentrifugatschälrohrs (7) in sedimentation. Centrifuge (1) according to any one of the preceding claims, characterized in that the outer edge of the peeling chamber (17), which lies on the outer side relative to the axis of rotation (4) of the centrifuge drum (5), extends to a diameter at least that of the rotational axis (3). 4) of the centrifuge drum (5) corresponds to the largest outside diameter of the solids cake (3). Centrifuge (1) according to one of the preceding claims, characterized in that it comprises in the drum cover (6) formed connecting openings (19) having a fluid channel for liquid or residual liquid (27) from a on the inside of the centrifuge drum (5) deposited solid cake (3) to form the peeling chamber (17) and which, relative to the axis of rotation (4) of the centrifuge drum (5) in the radial direction on the outside in the drum cover (6) are formed at a diameter which with respect to the axis of rotation (4) of the centrifuge drum (5) corresponds to the largest outside diameter of the solid cake (3). Centrifuge (1) according to one of the preceding claims, characterized in that it comprises a paring knife (23) for discharging the solid cake (3) deposited in the centrifuge drum (5), which does not co-rotate with the centrifuge drum (5) during the sedimentation operation but instead rotates in the rotation direction (28) of the centrifuge drum (5) is fixed, and which is designed such that it for scraping the solids cake (3) in a removal operation by means of a paring knife drive (24) from the axially lower side of the centrifuge drum (5) along the Drum inner wall in the centrifuge drum (5) can be retracted. Centrifuge (1) according to the preceding claim, characterized in that the downwardly open centrifuge drum (5) has a curved inner wall or a truncated conical section forming a truncated cone, forming a downwardly narrowing cone, and the paring knife (23 ) has a corresponding feed or path control. Centrifuge (1) according to the preceding claim, characterized in that the drum inner wall is frusto-conical, at least in a region along which by the peeling blade (23) solid cake (3) can be scraped, and the peeling blade drive (24) as a linear drive to the process or Delivering the paring knife (23) is formed along a rectilinear path parallel to the drum inner wall. Process for separating solid-liquid mixtures into clarified centrifugate (2) and a solid cake (3), in particular sedimentation processes, by means of a solid bowl centrifuge (1) having a downwardly open solid shell rotating about a vertical axis of rotation (4) Centrifuge drum (5), a drum lid (6) for closing the centrifuge drum (5), and a Zentrifugatschälrohr (7) arranged in the centrifuge drum (5) for withdrawing the clarified centrifugate (2) from the rotating centrifuge drum (5) during a with the Having centrifuge (1) carried out sedimentation operation,
characterized in that
for centrifuging the solid-liquid mixture, use is made of a centrifuge (1) comprising an annular peeling chamber (17) arranged axially above the drum cover (6),
in the drum cover (6) formed connecting openings (19) which form a fluid channel for liquid or residual liquid (27) from a on the inside of the centrifuge drum (5) deposited solid cake (3) to the peeling chamber (17), and
a residual liquid peeling pipe (21) arranged in the peeling chamber (17) for drawing off liquid or residual liquid (27) from the peeling chamber (17), wherein
during a drying operation, the feed of solid-liquid mixture into the centrifuge drum (5) is interrupted and the residual liquid peeling pipe (21) is activated so that the drying cake is dried in the drying operation Residual liquid peeling pipe (21) liquid or residual liquid (27) from the peeling chamber (17) is withdrawn. Method according to the preceding claim, characterized in that the residual liquid peeling pipe (21) at a high The rotational speed of the centrifuge drum (5), which corresponds essentially to the maximum rotational speed of the centrifuge drum (5) used in the sedimentation operation, is activated for drawing off liquid or residual liquid (27) from the peeling chamber (17). A method according to claim 13 or 14, characterized in that following the drying operation on the inside of the centrifuge drum (5) separated solids cake (3) in a removal operation with a paring knife (23) from the centrifuge drum (5) is discharged during sedimentation is not co-rotated with the centrifuge drum (5), but in the direction of rotation (28) of the centrifuge drum (5) is fixed, and for scraping the solids cake (3) in the removal operation by means of a peeling blade drive (24) from the axially lower side of the centrifuge drum (5) along the drum inner wall in the centrifuge drum (5) is retracted.

Images