DE2930312A1 - Screen-type centrifuge with washing fluid supply - at reduced speed providing thicker and less damaging film - Google Patents

Abstract

A screen-type centrifuge has an inner sieve with cylindrical walls and divided into pockets, and a frusto-conical upwardly widening outer sieve. Between these is a concentric drum-like cap which is supplied at the top with fluid for washing solid material adhering to the inner sieve wall. At high rotary speeds the washing fluid would form a thin and fast-flowing film and thus provide only ineffective washing. The cap is rotated at a lower speed than the inner and outer sieves, which may themselves rotate at equal or different speeds, and so produces a thicker and more effective film of fluid. The cap is freely rotatable, esp. on a fixed vertical filler pipe. The centrifuge is esp. for prodn. such as sugar which have readily damaged crystals. The rotary parts are readily replaceable and the drive is simple.

Description

The invention relates to a sieve centrifuge

according to the preamble of claim 1.

Such a sieve centrifuge has already been proposed (German Patent application 28 34 491.4), in which the hood in the form of a frustoconical Collar is firmly connected to the inner sieve part. The washing liquid is thereby fed via a hollow ring open on the radially inner side, which is connected to the hood is firmly connected.

As a result of the high centrifugal acceleration, the washing liquid forms but only a thin and very fast flowing film that is thinner, than the layer of from, which also flows over the frustoconical collar the solids thrown off the inner sieve part.

This is therefore only partially wetted with washing liquid.

The invention is therefore based on the object in a sieve centrifuge of the type mentioned, the mixing of the solid with washing liquid continues to enhance.

This problem is solved by one of the characteristics of the claim 1 appropriately designed sieve centrifuge.

Independent of the respective speeds of the 1..nmeron and outer Sieve part, the hood can be operated at a speed that depends on the viscosity of the washing liquid to form one for mixing with the solid leads to an optimal liquid film.

An additional improvement in the mixing effect is thereby achieved achieved that the solids thrown off from the inner sieve part as a result of the speed difference between the sieve part and the hood with high tangential velocity on the liquid film Due to the friction, the mixed solid is slowed down and falls with lower tangential velocity on the floor or the inner wall of the outer Sieve part, where it is accelerated again. Significant shear forces act again between solid and liquid, which results in further mixing.

Apart from the formation of a thick film of washing liquid on the wall of the Hood, the solid is thus intense twice mixed with the washing liquid, namely when it hits the inner wall the hood and when the already mixed solid hits the outside Sieve part.

In an advantageous embodiment, the inner and the outer screen part have the same speed, whereas the hood is fixed.

In this way, the transition from the inner Sieve part on the hood and aimed at the transition from the hood to the outer sieve part Achieve differential speeds.

For processing sensitive products, their components, for example easily breakable crystals, if you brake too hard and accelerate again could be damaged in an undesirable manner, with little constructive Effort, the speed difference can be reduced in that the hood rotates freely is stored. It can advantageously be placed on the centrally arranged filling pipe must be stored for the product to be processed.

Appropriately, the hood with a frustoconical, with Pre-accelerator provided with through holes for the incoming product be that for the pre-distribution of the product in the inner area of the inner sieve part protrudes.

Apart from improving the distribution effect, it can also do this an excessive acceleration of the hood through the tangential to the inner sieve part thrown off solids are counteracted.

Further features and advantages emerge from the following description based on the drawing and in conjunction with the claims.

1 shows a section through a sieve centrifuge according to the invention, FIG. 2 shows a half section through a further embodiment and FIG. 3 shows a half section by a sieve centrifuge according to FIG. 2 and a pre-accelerator.

The sieve centrifuge shown in Fig. 1 consists of an inner one Sieve part 1, which is firmly connected to an outer sieve part 2. Both screen parts have a common shaft 3, which has bearings 4 in the housing 5 of the sieve centrifuge is mounted and which can be driven via a pulley 6. The inner sieve part 1 consists of a sieve pocket centrifuge with a filling tube in its inner area 7 opens and in the perforated plate 8 for better distribution of the product on the sieve pockets are arranged. To discharge the filtrate separated in the sieve pockets Drain pipe socket 9 is provided.

The outer screen part 2 consists of a bottom part 10 and a adjoining frustoconical screen casing part 11 together.

Between the inner and the outer sieve part 1 and 2 is concentric and rotatably arranged a drum-shaped hood 12, the bottom part 10 of the outer Sieve part 2 is open. At the end of the hood 12 opposite the opening there is a ring line 13 with nozzle openings leading to the inner surface of the hood 12 are directed.

The ring line is connected to a feed line 14 for washing liquid connected. Another line 15 for washing liquid leads to the inner surface of the frustoconical screen casing part 11.

During operation, the product is fed into the inner area via the filling pipe 7 introduced the sieve pocket centrifuge and from there by means of the perforated plates 8 uniformly Distributed on the individual sieve pockets, where the filtrate is secreted and over the Drain port 9 is discharged. The remaining solid is in centrifugal Direction flung out of the inner screen part 1 and hits in the tangential direction on the liquid film of washing liquid located on the inside of the hood 12.

The liquid film is created by the uniform spraying of the Inner wall of the hood, 2 via the nozzles arranged in the ring line 13. Through this, that the washing liquid is only exposed to the acceleration of gravity, it flows relatively slowly along the inner wall of the hood 12 and forms one compared to the previous proposed embodiments are many times thicker liquid film.

In this liquid film with high tangential speed impacting solid is mixed intensively. It is slowed down due to the friction and falls with a lower tangential speed on the bottom part 10 or the Sieve jacket part 11, where it is accelerated again together with the washing liquid. This creates considerable shear forces again between the solid and the liquid, which cause further intimate mixing.

Although in the illustrated embodiments, the two screen parts 1 and 2 have the same speeds, a good distribution of the results is still achieved the inner sieve part 1 achieved solid discharged, since the difference in circumferential speed, which is necessary for the distribution of the product on the outer sieve part 2, of the fixed hood 12 enclosing the inner sieve part 1 bewie, and although in the way that the residue is first slowed down and then on the outside Sieve part 2 is accelerated again. It can therefore be designed with little Effort to achieve good mixing results.

In the embodiment of FIG. 2, the hood 12 is by means of a Bearing arrangement 16 is freely rotatably mounted on the filling pipe 7. A to tube 17 for washing liquid is directed into a radially inwardly open hollow ring 18, which is fixed to the hood is connected and has passage openings 19 leading to the interior of the hood 12.

In the illustration according to FIG. 3, another one with through openings is on the hood 12 provided, frustoconical pre-accelerator 20 for the inflowing from the filling pipe 7 Product intended.

The reference numerals 1, 2, 3, 9 and 10 used in FIGS. 2 and 3 refer to the objects with the same reference numerals in FIG. 1.

The use of the embodiments according to FIGS. 2 and 3 is recommended when processing products that contain sensitive components, for example easily breakable crystals. With such products, a to strong braking and re-acceleration lead to undesirable damage or lead to the comminution of certain components.

To dampen excessive braking and acceleration effects, the hood 12 @ be a Dre @@@ ver @ et @ t. according to those shown in FIGS. 2 and 3 Embodiments, the hood of the solid that is thrown off the inner tube is set in rotation. Make sure these solids are evenly distributed however, the outer screen part 2 is a larger speed difference therebetween Tube or the inner sieve part 1 and the hood 12 required. Because in the hood 12 washing liquid is entered, which cuts into it unaccelerated, there is also a braking effect. For example, have for the sugar industry Tests carried out show that when 40 parts of washing liquid are added au @ 10 part of the inner sieve part 1 discharged sugar in the hood 12 a speed which is roughly half the speed of the internal resp.

outer screen part 1 and 2.

Braking effect can still be achieved by arranging an accelerator 20 (Fig. 3) are reinforced, while the hood 12 not only from the washing liquid; but also slowed down by the incoming product. These arrangement We prefer to use it when the required amount of washing liquid is low.

In the embodiments according to Figures 2 and 3, the hood 12 also determine with the simplest means, so that they are like the one described in FIG Siebzen-trifuge can be operated.

The sieve centrifuges described represent preferred embodiments because it achieves optimal processing results with little construction effort can be. However, applications are also conceivable that require a separate, possibly adjustable drive for each individual rotor part, such as the inner one and outer sieve part and the hood 12 require.

Regardless of the simple structure of the screen centrifuges shown there are also the following special advantages: The drive of the centrifuge is simple. The rotating parts are easily exchangeable. At the buyer of the housing cover the centrifuge one removes the hood at the same time, so that the inner and the outer The sieve part is easily accessible, e.g. to change the sieve.

L e r s e i t e

Claims (8)

Sieve centrifuge claims 1. Sieve centrifuge with an outer, preferably conically widening upward part of the sieve, in which an inner, is arranged preferably formed from sieve pockets, and with a, between the inner and outer sieve part concentrically arranged, with washing liquid beauischlagbaren drum-shaped hood, which engages over the inner sieve part and itself opens to the bottom part of the conical sieve part, as you can c h -n e t that the hood (12) is one of the speeds of the inner and outer Sieve part (1 or 2) has different speeds. 2. Sieve centrifuge according to claim 1, d a d u r c h g e k e n n z e i c h n e t that the two sieve parts (1, 2) same or different Have speed and the speed of the hood (1; zero. 3. Sieve centrifuge according to claim 1 and 2, d a d u r c h g e k e n n z e i c h n e t that to act on the inner wall of the hood (12) with washing liquid a stationary ring line (13) provided with nozzles is arranged. 4. Sieve centrifuge according to claim 1, d a d u r c h g e k e n n z e i c h n e t that the hood (12) is freely rotatable. 5. Sieve centrifuge according to claim 4, d a d u r c h g e k e n n z e i c h n e t that the hood (12) is rotatably mounted on a (fixed) filling pipe (7) is. 6. Sieve centrifuge according to claim 4, d a d u r c h g e k e n n z e i c h n e t that with the hood (12) into the interior of the inner sieve part (1) more protruding, frustoconical, with through openings for the incoming product provided pre-accelerator (20) is firmly connected. 7. Sieve centrifuge according to claims 1 to 6, characterized in that that a hollow ring (18) open on the radially inner side is attached to the hood (12) is, the through openings (19) directed towards the outer surface of the hood (12) for has the application of washing liquid. 8. Sieve centrifuge according to at least one of the preceding claims, d a d u r c h g e -k e n n n z e i c h n e t that the hood (12) with a housing cover (21) is connected.