DE2130930A1 - DEVICE FOR EXTRACTION OF LIQUIDS FROM FIBER MATERIALS - Google Patents

Description

PAT ^p * 4TANWÄLTE ⁸⁹⁰² AUGSBUSG-GDGGlNGEN, den

DR. ING. E. LlEBAU u "," z "h. _o " ₈ 3S7 DlPi. ING. G. LI E B AU w «* -. *.« · * «,

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Your message from

William J. Nblan
1029 NE 23rd Blvd.
Gainesville, Florida / USA

Device for removing liquids from fibrous materials

The invention relates to a device for removing water, aqueous solutions or other liquids from suspensions of fibrous substances, e.g. suspensions of cellulose fibers, wood fibers, asbestos and the like .. The invention is primarily concerned with the removal of water, cooker waste liquor and bleach solution from fibers of wood pulp, such as kraft pulp, sulphite pulp, neutral sulphite pulps and wood pulp «

Although the invention can be applied to various technical fields, it was the first Line developed for use in paper mills and similar operations for washing pulps. The following The description therefore relates in the first place.

^ t) 9 H H 2 / U IS «)

official file number +

P 21 JO 930.8, "

on this branch of application. However, this one is special The description is only to be seen as an illustration of a possible application and not as a restriction of the invention.

For washing the waste liquids from cellulose pulp Until now, tanks with intermediate floors (diffusers), vacuum filters and screw presses were used. The diffuser wa shear, can be used very effectively for removing liquids *, but for countercurrent washing It takes a few hours because the process is based on the slow diffusion of concentrated liquid from the hollow lumens of the fibers through the cell wall is based in the diluting liquid flowing past the fibers. This process runs for modern, with high output paper mills work far too slowly.

Vacuum filters are typically used in paper mills these days, three or four of them to a battery interconnected to facilitate fluid withdrawal to undertake. To use such filters it is required, the pulp to less than 1% consistency (0.4-5 kg dry fiber per H5 kg suspension (1 lb dry fiber 100 Ib suspension)) to be diluted if a uniform cake is to be created on the filter drum. In addition, the drum can be used Do not cake the liquid below 3Λ to 15% consistency revoke. I have found that cellulosic tracheids, or lignin-deprived fibers in the hollow lumens of these fibers about 181 kg (H, 0 Ib) Water or f, Ö times the specific gravity of the liquid may contain. That says that the cellulose fibers if all external fluid, i.e. all fluid, that is not held in the fiber lumen is removed,

could provide a filter cake of 20% consistency. Since the vacuum filter makes its fiber cake with IU up to 15% Consistency, the fibers released by the first filter must be practically all of the original contain concentrated liquid contained in the lumens and a small amount of external liquid. The fiber mat from the first filter is mixed with diluted waste liquor and immediately placed in the trough of the second Filter pumped. .The concentrated liquid inside the fiber will not have time to diffuse into the surrounding diluted liquid left. The washing-out effect of vacuum filters is therefore low. That means, that an undesirably large amount of concentrated liquid remains in the fiber lumen.

Screw presses, on the other hand, work very effectively, because they rely on the compressibility of the hollow cellulose fibers Make use. If the press is operating with an outlet consistency of 40% it is not just the whole withdrawn from its fluid, but there is also a large amount of the fluid contained in the fiber lumens expressed. At the point where the fiber begins to compress, i.e. at about 20% consistency 0.45 kg (1 lb) dry fiber 1.81 kg (4.0 lb) liquid inside the fiber. At 40% consistency, 0.45 kg of dry fiber contains only 0.67 kg (1.5 lb) of liquid. Thus were 1.12 kg (2.5 lb) of internal fluid expressed what 62.5% of the total internal fluid is equal. If the press releases a pulp with a consistency of 65%, thus 8 6.5% of the internal fluid has been expressed.

the compressed fiber cake the compression zone leaves the press, the fibers, which have an isse elasticity, at least partially jump into it

Shape back. The usual ones today

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Screw presses let these fibers stand in the air expand, after which dilution liquid is added after fiber expansion. Hence becomes a certain Time required for the dilution liquid to enter the fibers diffuse and displace the air absorbed during the previous fiber expansion.

The first feature of the invention relates to the exclusion of such air intake. According to this feature, the discharge end of the press is completely enclosed, apart from lines for the admission of the diluting liquid and for the discharge of the diluted pulp. The discharge area is kept completely filled with pulp and liquid, whereby the contact between the press cake, ie the compressed fibers plus trapped liquid and the air is prevented. When the fibers expand, diluting fluid is immediately drawn into the hollow lumens of the expanding fibers. Stirrers in the discharge area loosen the cake to a uniform suspension that emerges from the press. In such a treatment takes 0.45 kg of a compressed on HO% consistency Trokkenfaser 1.12 kg (2.5 Ib) dilution liquid, with the 0.67 kg, (1.5 Ib) of concentrated liquid in the fiber lumens remained mixed. Then more dilution liquid is added so that the flowability of the fiber mass is established for its discharge. The outflow from the press can now be transferred directly to a second press in which the substance passes through a second pressing stage. So you can see that a properly executed screw press works much more efficiently and removes the liquid faster than any diffuser tank or vacuum filter,

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A major difficulty in screw press design is due to the large volume changes that have to be made in the press. The following The calculation example is intended to illustrate the magnitude of these volume changes, the starting point being one Cellulose pulp of initially 3% consistency (1.36 kg (3.0 lb) dry fiber in 45 kg (100 lb) suspension). This suspension should be removed up to a consistency of 40% liquid. Under the simplifying assumption that the ' specific gravity of the suspension is 1.0, the initial volume per 4.5 kg (100 lb) of dry fiber

4.5 kg
= 151 1

0.03 8.33

The final volume at 40% consistency with a specific weight also assumed to be 1.0

4.5 kg

= 11.4 1

0.40 8.33

The decrease in volume between these two final states is 151 1 - 11.4 1 = 139.6 1 (40.0 - 3.0 = 37 gal). if such a change in volume is to be made in a screw press, 'results in a very difficult one Construction problem because at the inlet end a volume 13.3 times as large as at the outlet must be provided send"

Starting from the same example with 4.5 kg (10 Ib) od pulp, which is to be concentrated from 3.0% to 40.0 % od consistency, the table below shows how the volume changes with the consistency.

Base: 4.5 kg (10 Ib) o.d. Pulp - all like suspensions have a specific gravity of 1.0. Inbound consistency

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q * iqe * t

3.0% o.d. Fiber; 151 1 / 4.5 kg (40 gal / 10 Ib) o.d. Fiber. Final consistency 40% o.d. Fiber; 1.36 1 / 4.5 kg (3.0 gal / 10 lb) o.d. Fiber"

Total change in volume 139.6 1 (37 gal).

Medium
Consistency -
4 od fiber) Middle
Volume 1 / 4.5
(gal / 10 Ib
Fiber) (30.0) Volume change
kg of 3%
1 (gal) (10.0) % of the total
Volume change
tion - 4.0 114 (20.0) 3 7.9 (20.0) 27.0 6.0 ■ 75.7 (15.0) 75.7 (25.0) 54.2 8.0 56.8 (12.0) 94.6 (28.0) 67.5 10.0 45.4 (4.8) 10 6 (35.2) 75.7 25.0 18.2 (3.0) 133.7 X37, O) 95.2 40.0 11.4 139.6 100.0

It can be seen that more than 75% of the total change in volume occur when the consistency increases from 3% to 10% will. If it. would be possible this dehydration from 3.0% to 10.0% to be exercised through a filtering process, only one needed relatively small volume change to be considered. In such a case, the volume needed at the entrance end to be only 4.0 times as large as the original volume, compared to a 13.3-fold magnification, when the press completes all of the dehydration.

The basic mode of operation of a screw press is known per se. which are attached to a central rotating spindle - ■ push the pulp through a cylindrical tube or a drum, the walls of which

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kenden (permeable) material, such as a wire mesh, perforated plates or in the longitudinal direction of the drum closely spaced rods. A mechanical pressure from the rotating screw acts on the Pulp suspension, whereby the pulp through one from the entry end of the press to its exit end ever smaller cross-sectional area is pressed. This reduction in cross-sectional area can be achieved by increasing the spindle diameter in the direction of the exit end or by reducing it the drum diameter. Further compression results from one from the entry to the exit end progressive reduction in the slope of the helical surfaces. The by the slope of the helical surfaces Forces generated by the speed of rotation of the screw provide the energy to pass the pulp through die press «The decreasing cross-sectional area and screw pitch press liquid out of the fibers and through the permeable drum and press the fibers closer together.

If the mechanical structure of the press is fixed, the theoretically occurring liquid removal can be calculated for any amount of food and input consistency. If the cross-section of the ring between the drum and the spindle at the inlet end is designated with A. and the Sehraubenstei.gu-ng at this end with P, then the inlet amount per revolution is AP ^. If the cross-section and pitch at the outlet end are designated with A "and P" in the same way, then the outlet volume per revolution is A _? P ", The volume of the liquid expressed in each revolution is therefore theoretically AP - A" P ₂ »üas the volume of liquid withdrawn per minute would be (AP - A" Po) R if R is the speed

? (J 9 ü B 7 I 0 1 0 B - BAD ORIGINAL

the screw per minute is.

In the table above, in which the percentage change in volume is related to the change in consistency it was found that a 13.3-fold change in volume is required to produce a pulp suspension to bring it by pressing from a consistency of 3.0% to a final value of the consistency of M-0.0%. One sees without further ado, that extraordinarily strong changes the spindle diameter and the helix pitch would be required to achieve this decrease in volume. I have found that too much a wedge shape of the spindle shaft causes a large decrease in volume can lead to an extraordinarily high power requirement and even clogging of the press.

An analysis of the problem of dehydration from fibrous material shows that two different processes take place. At low consistency values, up to a consistency range of approximately 10 to 15%, each depending on the properties of the fiber in question, the suspension behaves like a hydraulic fluid. The liquid can flow around the fibers and the Fibers can flow around each other to a limited extent. In such a case the main resistance is against a flow of liquid through the filter element from the entangled fibers resting on the filter element remain when the liquid permeates it. When these matted fibers or the cake of the flow offers little resistance, most of the liquid will flow through the fiber mat and it will remain as Residue a solid mat, kept moist from remaining liquid, which / now has the properties of a solid Phase instead of that of a hydraulic fluid

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owns. The liquid left in this mat can only be done by mechanical pressure or by drying be eliminated. The removal of the slightly removed Liquid through the filter element is hereinafter referred to as 'filtration' while squeezing the liquid retained in the mat or filter cake should be referred to as pressing. That clearly separating these two dehydration mechanisms constitutes the second feature of the invention represent.

The resistance presented to a flow by a fiber mat formed from pulp fibers or a fiber cake should not be neglected. As the thickness of the cake increases, so does the resistance to the flow of liquid passing through the cake. This resistance of the cake to a flow of liquid passing through depends on the type of fibers to be filtered out; For example, kraft pulp fiber mats offer much less drag than semi-chemical pulp mats and these in turn have much less drag than wood pulp cakes. It would therefore be very advantageous if the cake or the fiber mat, as soon as it has formed on the filter element, would be returned to the pulp suspension, because this would mean that the resistance to the flow of the liquid through the filter element would have a minimum value while the pulp was in process is thickened. This constant return of the freshly emerging fiber mat or the newly formed cake into the mass to be thickened represents the third feature of the invention.

A fourth characteristic is the magnitude of the driving force, those during the implementation of the filtration process

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can be used to drive the liquid through the filter element. With a standard rotary vacuum filter the driving force is limited to one atmosphere or less, depending on the temperature and that of it following vapor pressure of the liquid to be discharged. In the invention, the entering into the press can flowable medium hydraulic pressure can be exerted by a pump. The pump capacity must be so large * be that this hydraulic pressure across the filter

'tion section of the device remains practically the same. In addition, the will. Filtrate collecting container surrounding the drum made pressure-tight so that the filtrate can be drawn off by a pump or a siphon, which creates a strong vacuum inside the container will hold. In this way, hydraulic pressure is applied to the inside or suspension side of the filter element is effective and a vacuum on the outlet or fiI-tratseite, Much higher driving forces can be used for the filtration than with ordinary filters be available.

When the filtration is driven as far as possible, that is, to the point where the thickened material is no more than hydraulic. Liquid acts, rather behaves like a semi-plastic solid, the filtration principle is no longer applied. Instead, mechanical forces must be applied so that the semi-plastic material can be pressed into a smaller volume as it moves through the device. Now the resistance to the flow of liquid is no longer created by the cake on the filter element. Rather, the actual semi-plastic fibrous substance itself forms the resistance to the flow of liquid. There are forces

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-Mr

that press the fibers very closely together, the approximately cylindrical cellulose fibers are also pressed flat so that the hollow lumens of the fibers collapse and push the fluid it contains out through the cell wall. There is also a Power required to continue the liquid moved in this way through the spaces between the tightly packed Fibers and from there through the filter element.

Studies on screw presses have shown that uninterrupted helical surfaces with the incline decreasing towards the outlet end Helical surfaces commonly used in screw presses are preferable. Such right designed, uninterrupted screw surfaces ensure that a thickened cake is continuously discharged without the aid of stoppers or other aids at the outlet end to obtain such a thickened discharge. The consistency of this discharge can can be controlled by the speed of the screw and the amount of material supplied to the press. on the other hand interrupted screw surfaces on the press spindle have two major disadvantages. First the exit end must be sealed until the cake is strong enough; second, call the established ones Rods or corresponding devices in those formed by the interruptions in the screw surface Gaps - sticks that are supposed to prevent the pulp from circulating with the screw - actually that high Shear forces in the thickened pulp show that the ejected cake is always very hard and dense. A medium, not so high consistency of the emerging cake cannot be achieved. With others Words: when using snails with interrupted

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serve visual surfaces ordered no way to Controlling the consistency of the exiting material.

It has also been found that tilter elements, which consist of closely spaced, longitudinal rods, are inexpedient. It has been claimed by others that these parallel, longitudinal bars act as wedges that prevent the pulp from circulating with the screw. It is doubtful that this is the case, but on the other hand it has been shown that a certain regulated ¹ bar circulation of the pulp with the screw is very desirable. This partial rotation of the pulp cake together with the screw leads to a shorter pitch than is normally provided in such screws. Assume that one very helical turn in the series of screw turns on the spindle has a pitch of 15 cm (6.0 in.). If there is a slip of 100% between the guide surface and the screw thread of the pulp, then the Pulpenkuchen moved at each revolution of the 'worm by 15 cm (G ₅ O in.) Forwards. If, however, there is sufficient friction between the screw turn and the pulp that it propels, the pulp rotates to a certain extent in connection with the corner of the screw If one sixth of the force exerted by the riächc is converted into rotary motion of the pulp and only lürii sixth;! Into longitudinal motion of the pulp, the pulp cake rises by only 1 ?, B cm (6.0 in. ) with each revolution of the tendon forward. Assuming the same throughput of dry pulp in both cases, that with the snow:]. ^ "with running pulp one sixth Uu ¹ GH volume through the perforated. Drum expressed in Torrn of liquid compared to that without expressing liquid

o 9 8 8 2 / ο 108. ^βΛ & original

the process taking place vary when the pulp is not rotating. The deliberate application of forces opposed to movement of the pulp at the end of the press can therefore induce π-flammable friction between the screw surfaces and the cake and result in this desired rotation and the application of larger changes in cake volume than it does from mere changes in cross-section and screw ^{pitch would be expected, Therefore 1 it is} recommended to use perforated plates or grids as a liquid drainage area instead of the closely spaced longitudinal rods, The construction is more economical and the pressing process can be controlled better.

Two methods have emerged with which to use the forces that resist the forward movement of the pulp at the exit end of the press. According to the first method, there will be a no at the exit end Spindle piece provided with screw surfaces is provided, however, this is not an interruption in the screw thread surface to watch"

Between the spindle piece not provided with screw turns and the point at which the pulp cake is ejected are no longer very convoluted surfaces intended. The cross-section through which the pulp flows in this section should be kept constant. Since there is no screw turn in this section that could propel the pulp forward, the force required for forward movement from the last screw surface before the free screw surface Section to be delivered. This creates additional force between the screw surface and the pulp cake an additional friction that leads to some rotation

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SAD

- LH -

of the cake leads, it is important to let the dratn-ige drumming L v, I extend over this ochraubunflachen section, because a certain increased pressure caused _{by the c m:;}

These surfaces of Schraubenwindurvgo kept free portion has the ffachteil that he Curr and illustrates operation can not be changed, Est he -ainmaL hargerLehntet, so it can be shortened or lengthened only by disassembly of the exit end of the press. The most appropriate use for this is to modify a press designed for a specific problem of dehydration, if it is necessary to press the same material to a slightly higher consistency than the original press allows, the pressing area can be increased by installing this component will. It can also be used if the press has to be converted for a new material from which the liquid is somewhat more difficult to remove than the previously treated material. The invention «feature can also be used in the original press design if you want to use significantly higher raw screw numbers, with a lower torque and therefore lighter spindles, screw thread surfaces and bearings»

Then a further device will be described with which the forces at the exit end of the press are increased against which the screw thread surfaces have to work. This method has the advantage of being controllable, i.e. the resistance forces can be controlled during the operation of the press can be increased or decreased. This method makes use of the fact that the When leaving the press, the cake always has a certain

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213U93Ü

be ^ egun ,? executes. If at least one ί est standing S1 from od '(iv finger is disposed no that it eht in longitudinal "ri ung protrudes into the Aust vi tt soff direction for the cake, so the moving cake on that rod or these rods must A sharp channel on each of these bars, facing the oncoming pulp, improves the flow of the pulp past the bars. Since the bars stand still, the rotation of the pulp is completely interrupted, and the only movement of the cake is in the longitudinal direction into the exit section into it.

This breaking or stopping of the rotational movement of the pulp at the exit end of the press leads to high shear forces in (! (In the pulp cake ο the pulp rotates in the direction of flow above the rods standing upright. After the pulp has passed the front ends of the rods, it cannot mine be in rotation. ¹ Therefore, the cohesion or adhesion between the fibers by a force has to be broken, which is sufficiently large that it can produce this effect in the seer Pulpenkuchen _t

If these rods or rings are fastened to the press booth, the one insulation of the pulp produces a force that is firmly applied and the corresponding force that the screws of the price must exert is also present ringer, however, is attached to a hollow shaft surrounding the opindelwel Ie and ? λιϊ already hollow shaft and spindle shaft friction-poor bearings vc) rgf ;;, "<: hen are, the run into the pulp cake- i'ny-iiiuH-ii ringer with your Cake, um, and the only force evoked in d (i (i 1 uclien is the ^{force required to slide (If 1} S l'ufJieiU3 on the fingers, Wenn

* ^ϋ 9 Ö 8 _{2/018 8 6AD OR | Ö | NAL}

213Ü93Ü

a brake drum is now attached to the hollow shaft and brake shoes that interact with it are provided on the outlet housing, can be applied by exerting pressure Working cylinders that actuate the brake shoes, the rotation of the fingers is reduced or completely prevented will. In this way, the increased forces that the helix surfaces transfer to the pulp are removed must be controllable. Instead of a brake drum with brake shoes, other devices, such as a worm, can also be used with worm wheel, which are driven at a controlled speed, can be used.

It has been shown that such fingers have a decisive influence on the operation of a screw press to have. For example, if the press with such a supply of Kraft pulp of a certain consistency and such a spindle speed works that a cake of 25% consistency is dispensed, so that increases Insertion of two fixed fingers in the cake outlet area the cake consistency to 30 to 32% o.d ,. It has also been found possible to use these fixed fingers and the consistency of the ejected cake constant at 25% o.d. by increasing the spindle speed by about 25% will. With such an increased spindle speed, of course, the capacity of the press increases.

The use of fingers, which can be restricted in their rotation by means of an adjustable force, in the The exit area of the press offers another major advantage by increasing the flexibility of the press out. In this way, the operation of screw presses can be controlled automatically achieve. For example, assume that pulp contains

209 8 8 2/0 188

constant feed rate is introduced into the press and a constant consistency of the Auüstosses must be achieved. A slight change in filterability the fibers would normally have a change in consistency at the exit and a corresponding change of the filtrate volume. A flow meter the change in the filtrate throughput could occur in the filtrate line scan and send an electronic or pneumatic correction signal to the cylinders, which the Control the braking effect on the shaft to which the fingers are attached. In this way, the Forces exerted on the pulp mass can be increased and decreased accurately and automatically control the consistency of the output.

Preferred embodiments are shown in the drawings of the invention, and the figures have the following meanings:

Fig. 1 is a central section through the complete device, the filtration section is here left, the press section right;

Fig. 2 is an overview of two fixed fingers, the attached to a ring secured by screws to the ejector housing of the press;

Figure 2A is a central section through the ring of Figure 2;

Fig. 3 shows schematically part of a modified form according to which the rotation of the fingers during the operation is controllable;

Fig. 4- is part of a central section through a modified one Structure of the feed and fiI

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-LG-

tration section of the Von · Ich111114 ;;;

FLg * 5 gives a section lamas of the line V- / in> L, η ν; ieder; .

FIG _o 6 shows a section along the line VE-VE in Fig. 4;

Fig. 7 shows a section along the line VEI-VEE - * in Fig. 4;

Fig. 8 corresponds to a part from Fig. 1, but in a modified form,

In the inlet line 1 nach.FLg ₈ L a pint suspension of low consistency, z.ß. 2.0 to 4.0 I cud. Fiber to be imported; the feed pump for feeding pulp to the device can be operated with any pressure gradient.

The outer housing of the press, which is structurally stable and has a filtrate container, is marked with 2 designated. The flanges 3 serve as terminations, partitions and reinforcements .. The inwardly protruding concentric rings 4 on the housing 2 form holders for the filter element 6, which consists of a perforated plate or a net backed by a perforated plate. In the rings 4 Openings 34 are drilled through which filtrate into outlet 5 of the press section can flow off. The press spindle is denoted by 7; it has a shaft 8 (their stuffing boxes and external bearings are not shown are) running in the axial direction through the filter section runs through *

209882/0188 SAD original

2 -130 9

- ia -

According to FIG. 1, there is a separately driven hollow shaft 10 mounted on the shaft 8 and rotates around it. Four scrapers or squeegees 11 are attached to the shaft 10. These scratches 11 remove the pulp cake from the tilter element 12 immediately after it has been deposited and bring it this thickened pulp into the more thinned bulk of the pulp. This separately driven hollow shaft 10 is required when the speed of the press main spindle is low, about 10 rpm or less. If higher spindle speeds are used, up to 30 to HO rpm, so this separately driven hollow shaft is not required. Instead, the one in Tig. 4 construction shown to be used.

Fig. 4 shows a modified construction of the filter section The components which correspond to those drawn in FIG. 1 have the same reference numbers with an appended "A" obtain. According to FIG. 4, the pulp suspension is introduced through the arm IA of the T-piece 40. On the shaft 8A is a screw surface section within the T-piece 4 0 3 5 provided, whereby a better feed line to the filtration section compared to the arrangement can be reached according to Fig. 1,

Fig. 4 also shows that the change in the spindle diameter for the most part, but not entirely, occurs within the filter section. In this filter section are frustoconical collars 37 placed on the frustoconical spindle 7A and are through at least one wedge k rotatably connected to the spindle. There are four pairs of arms 36 on each l'anschette part attached to which the scrapers UA are screwed. Since the spindle 7A in the counterclockwise direction (Fig. I), 6 and 7), the pulp is removed from the filter

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BATH ORIGINAL

element 12A scraped off and from the curved top " the scraper moved to the central area, where it is mixed with the more thinned pulp. the Forming the cuffs 37 as sections serves a dual purpose. First, the route can be along the longitudinal axis on which the scratches are to work can be changed by at least one of the ones shown Cuffs 37 by another cuff of the same dimensions but with screw thread surfaces attached to them exchanges. The slope of these helical surfaces will be a little larger than that on the right in Fig. 4 drawn slope P .. Second If one of the arms supporting the scraper 11A breaks, a single cuff can be replaced without that high repair costs arise.

The scratches HA do not need to be screwed to their holding arms 36, as shown, they can also be screwed welding. However, scratches attached with screws or the like can be replaced more easily when they are worn are. Wear of the filter element 12A can be avoided if thin metal strips are in the form are attached to the filter element by circular rings or as a spiral. The arrangement can also be carried out in this way be that after the scratch has passed a thin layer of pulp adheres to the mesh; this layer reduces fiber losses to the filtrate to a minimum. Leaving a tight space between the scraper edges and the filter element would serve the same purpose as attaching metal strips and would reduce the wear and tear on the scratches.

Both the hollow shaft 10 according to Fig? 1 as well as those in Man-

209882/0188

cuff split SpindeL 7Λ according to Fig. 4 are conical formed, the diameter increasing in the direction of the pulp flow. This cone structure leads to a decrease in the ring cross-section through which the pulp flows, which in part compensates for the strong reduction in pulp volume which, as mentioned above, occurs during thickening. It is not necessary to reduce the total volume decrease to compensate for the flow cross-section for the pulp. Part of this change in volume can be achieved by reducing the straight-ahead speed of the pulp clamping compensate; this suspension is in the filtration section pretty flowable.

The filtration section serves to remove as much liquid (filtrate) as possible from the pulp while the pulp suspension still has the properties of a hydraulic one Fluid has »(The term" hydraulic fluid "in this context is intended to denote a system in which the fibers can move as separate elements and in which one exerted on the system Pressure spread in all directions. It should be noted that the filtrate discharge line 14 or 14A is essential is wider than the filtrate discharge line 5 in the press section. This difference in the line widths is essential * because that is in the filtration section when filtering from the inlet consistency to The volume carried away to the range of 10% consistency is much larger than that when pressing to the final consistency withdrawn volume, a vacuum is applied to line 13 or line 13A to provide the driving force for To increase the liquid drainage during the filtration, one connects the line 14 or 14 A either with a siphon with a fall water tank or with a stepping pump, ·

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BATH ORIGINAL

2 Kl ü 9 3 Ο

In the press section of the device, one or more screw thread surfaces are lined up on the 3 spindle 7. The slope of the first complete turn of the screw surface is denoted by P. As you can see, in this section of the press, which is provided with screw surfaces, the spindle 7 is drawn with a constant diameter. if possible, to keep this diameter constant, because the pulp has lost most of its flowability in this section and is resisting the change in direction associated with the increasing spindle diameter Cross-section through which pulp flows, and thus the pulp volume in Fäl len, in Danes the necessary volume arid is not particularly favorable to bring about by simply lowering the pitch of the screw. In these cases, the change in the spindle diameter should be made as gradually as possible at the wet end of the press (end on the left in Fig. 1).

Since the annular space between the spindle 7 and the Draimigenetz 6 of Figure 1 consistent Grosse, the achievable in this section change in the lumen Pulperiva a function of P. and P _1. By reducing the pitch of successive turns of the helical surface, a sequence of turns can be designed which brings about any change in consistency within the limits set by the inlet consistency and the pulp properties.

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The change in slope - in contrast to a change in slope with each turn - results in a more effective one Way of working.

If the cross-sectional area of the annular gap, the slope of the first complete turn and the consistency of the the pulp entering the first turn is known, one can calculate the theoretical weight of the dry pulp that can be handled by the press at any given speed. Furthermore lets the final consistency can be derived from your known ratio of P. to P. to calculate. These calculations are based on the assumption that all are generated by the rotation of the screw Forces are converted into translational movement of the pulp in the longitudinal direction of the press. However, it occurs in particular with a high consistency at the points of contact between pulp and screw surface, sufficient Friction to bring about a certain entrainment of the pulp by the screw in the sense of a rotary movement. This inhibition actually works in favor of an increased Dewatering capacity of the press in the following way. When the pulp is in the last turn in one turn the spindle is actually carried along by 30 ° by 360 °, a forward movement of the pulp takes place in this turn over a distance of

360 - 30

360 ^Λ η

The drainage effect is the same as if it were The slope of the last helical surface is not P, but

360

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This principle of pulp rotation becomes an advantage in the next part of the press referred to as the non-helical section. The diameter of the spindle 7 remains constant here, but there are no helical surfaces on the spindle. The annular space between the drainage network 6 and the spindle 7 is filled with dense pulp. This pulp must be pushed forward from behind it in the helical (press) section. This increased resistance must be overcome by an increased force which is exerted on the pulp by the screw surface. This increased force or pressure causes the pulp to rotate more and move somewhat less forward. 'The resistance in this helicoid-free section has therefore a further apparent reduction in the Schraubenf lächensteigung result and, accordingly, an increase in the drainage drier at a constant flow rate pulp ₀ It should be noted that the drainage system 6 is also present in this (helicoid-free) portion so that the liquid squeezed out by the forces exerted can be discharged through the network.

According to Fig. 8, the screw surface-free portion of the Press can be removed from the rest of the press. For this purpose, flanges 15 are provided as well as a removable spindle section 16. This arrangement is made "so that the section free of screw surfaces can be freely selected with regard to its length and adapted to changed drainage conditions. The spindle shaft 9 has a key and corresponding grooves are provided to receive a rigid cylinder 16, whose inner diameter corresponds to that of the shaft 9 and whose outer diameter corresponds to that of the spindle 7, see above that a section 16 of any length can be inserted .. Also the outer drum 2B with the net 6B, the

209882/0188

section 16 are interchangeable. This screw A section free of silts thus represents a means with which a stronger drainage can be achieved than just by the final ratio of the screech slopes,

Another device for increasing the compression effect of the press is shown in FIG. 1 at 17 and in the details of FIGS. 2 and 2A. The device is made of metal, usually of steel or stainless steel, wherein the ring ¹ K) is screwed into the ice gezeichnfiten V / to the flange of the press. Attached to this ring are two flat square fingers or rods U1 which protrude into the space between the spindle 7 and the net 6 and act on the pulp cake when it emerges from the annular space between the spindle 7 and the net 6. When the pulp cake approaches these angular fingers, it rotates at a fraction of the rotational speed of the spindle. When the cake slides past these protrusions, the cake stops rotating and all further movement of the cake consists of a longitudinal translation der Presse «At this end of the rotation, the cake is subjected to shear stress, whereby fibers are pulled apart and to the side. Energy is required for the sawing effect, which is supplied to the pulp by the screw winding surfaces. Because of this device 17, the screw surfaces have to exert higher forces on the pulp, the pulp is subjected to a stronger rotation in the screw turns near the outlet end of the press and, in the end, there is an even greater ratio of P. to P with a corresponding increase in the drainage effect. If a stronger dewatering is undesirable that Feist stationary, projecting in the pulp "finger" can ^1H be used to a higher Pulpendurchsatz without higher Endkonsi-

209802/0 188 bad original

s tence can be achieved by increasing the spindle speed *

3 shows a modified embodiment of this device, in which the shearing action transmitted into the pulp can be made variable in order to adapt to the working conditions that can rotate freely around the spindle * drive shaft 9. A brake drum 19 is also attached to the hollow shaft. Brake pads 20 actuated by hydraulic cylinders 21 are able to exert pressure on the brake drum »If the full shearing action of the fingers against the pulp is to occur, a sufficiently high pressure is exerted on the hydraulic cylinders 21 so that the hollow shaft 18 is shut down» Should no effect against the fingers of the pulp occur, the cylinders are full printing t Lists> and the fingers and the hollow shaft rotate with the same speed as the Pulpenkuchen, any required rotational speed between dLeEWn two limit values can be achieved by varying the pressure on the cylinder 21 obtain, thereby, a controllable resistance can be exerted on the pulp rotation. The pressure on the cylinder 21 can be made dependent on a suitable control, in order to achieve an automatic. Adjustment as a function of the operating conditions. For example, as shown in FIG > 1 is returned,

The last, eier ejection section of the press is referred to in Ei.gl as the atomization section »This dilution

0-9 882/0168

BATH ORIGINAL

section is only used when the press is used as one stage in a multi-stage washing process is. Immediately after the compressed cake leaves the device 17 of the press, it is with Brought into contact with diluent or water, that is fed through the pipe, As the cake stretches again because of the elasticity of the fibers, the dilution liquid will enter the hollow lumens of the Fibers sucked. Therefore, the dilution stream mixes almost instantly with the remnants of the in the Fibers after pressing remaining liquid of any concentration.

If the ejection end of the press had to be designed in such a way that at the moment the pressure was released from the fibers and on its return to its natural form, air would have been able to gain access to the cake, so air would enter it Fiber lumens are sucked and mixed with the concentrated liquid remaining in these lumens. As a result, several hours of communication between the pulp and the diluting liquid would be required ^ " diffusion of the concentrated chemicals remaining in the fibers into the bulk of the To achieve dilution liquid.

A housing 23 is placed around the dilution section so that this section remains filled with pulp and diluting liquid wedge and thereby the undesired contact between the re-expanding fibers and the air is avoided. The hollow shaft 24, which is driven independently from the outside of the press, is provided with stirring paddles 25 so that the pulp suspension is sufficiently mixed before it is transferred through line II to the next washing stage.

209882 / 018Ö

BAD ORiG _{? NÄL}

213Ü930

When a fingered hollow shaft 18 is used in the ejection section, as shown in Fig. 3, the mixing of the press cake with the diluting liquid can be achieved by stirrer on shafts above and below the hollow shaft and at right angles attached to her. The agitator shafts enter and exit the housing of the discharge section Stuffing boxes or mechanical seals and are made by outside driven at a suitable speed to make the cake break up in the dilution liquid.

If a fiber product with a very low moisture content is required, the cake will cook through immediately the large opening (e.g. 27 in Fig. 3) led away without any addition of diluting liquid. In these cases it may be advisable to rotate in the ejection section Build in devices so that the cake is split into small pieces to make it easier to eject will. The housing surrounding the discharge section, which in FIG. 3 is in the form of a tube with a large discharge opening is drawn on the bottom can actually also be designed to be completely open so as not to prevent the cake from being ejected To put an obstacle in the way.

The invention is as a combination of those described above To understand the characteristics, but not all characteristics are realized in one and the same embodiment to become. The number of features used in a particular implementation is determined according to the requirements given by the respective circumstances «

In general, with a complete construction the filtration section is provided at the entrance. In this

2 09882/0188

Filtration sections are always circumferential scratches or HA for the continuous removal of the fiber mat or of the cake may be provided by the cylindrical filtration network 12 or 12A, which also has the cake in the direction Slide it back onto the central shaft and mix it with the more dilute main part of the suspension. The rotating shaft on which the scrapers are attached increases its diameter from the entry end to the outlet end of the filtration section there. However, this increase in diameter does not take up the entire increase in diameter of the spindle to represent the total length of the device. Part of the total increase in diameter may be in the pressing section take place, which connects to the filtration section,

If the main spindle shaft moves with sufficient speed Speed drelyt, around 20 to 35 rpm, is an extra one driven hollow shaft 10 at the inlet or »at the filtration section the press is not required. The section with increasing diameter and added scratches, can be used as a structurally uniform part of the main shaft can also be made from a hollow shaft IQ or consist of annularμ sections 37, which are keyed onto the main shaft.

As a drive for the decrease of the liquid in this Filtration section can be either hydraulic pressure these, eggs on the suspension entering the section is exerted, or also vacuum »the outer surface surrounding the cylindrical filtration network 12 Housing 2 is placed, or a combination of hydraulic pressure and vacuum, in no case the ge ^ curved. Scratch 11 or LlA a mechanical pressure

208882/0188

-3Q-

exercise to carry away the liquid. you will be only used to remove the fiber cake when it settles on the net cylinder, and around the Cake attributed to the main part of the suspension.

This filtration section must be used in the systems where the supplied fiber or pulp suspension low consistency ranging from about 1.0 weight percent insoluble solids to about Has 5.0 weight percent insoluble solids. If the suspension supplied to the system is in the area between about 8.0 and about 12.0% insoluble solids moved, the filtration section would be of little use and could be omitted.

The screw press section is part of the overall plant can always be used to a certain extent. If up to one fourth of 25 weight percent insoluble solids or is pressed higher, this press section forms the greater part of the total length of the device, The number the visual surfaces on the revolving spindle, the Measure of the reduction in the pitch of these screw surfaces from the wet to the dry end of the presser from the cut and the spindle speed represent the ¥ ariables that through the press properties, s.chaften of the fiber materials to be treated and by the degree of compression required be determined.

The compression properties of the Fasorin material to be treated should be in a special press before Kanstryktion can be investigated experimentally. I leave that very much easily done in a hydraulic laboratory press. The pressing section for the experiment consists of

Q9ia2 / Q1ia ORIGINAL! NSPECTED

a small lattice cylinder, with the Metz openings as well; '. are tall as in the final construction; The outer cylinder becomes concentric with the interior of a strong steel cylinder of about 2.5 to 5 cm (1 to 2 in.) welded to a junction knife lying across the diameter of the lattice cylinder. In aera lattice cylinder is concentric arranged in a rigid array. The vastness of the Rinjrauias between the rigid shaft and the grid should be just as big as the thickness of the cake to be produced in the commercial press. fJin sealing plunger serves as a piston, the ax pulp cusp presses into the lattice cylinder, whereby the filtrate is pressed through the mesh openings. This between the punch and the table of a hydraulic press Small press arrangement used can be used for extraction the characteristic curve for dehydration (percentage consistency applied over the pressing time) for that to be treated in the commercial press Pulp can be used. Ks will show that various Curves, which are for different, identical ones Pressing forces are recorded, run parallel to the time axis after approximately the same pressing time, These ^ Press time is the retention time for which the press is designed must become. The total length of the press can thus be precisely adapted to the pulp to be pressed.

If in special cases the required liquid content is maintained of the end product is still very high and, for example, between about 10 percent fiber solids and 16 Percent fiber solids, the press section can very kuri: held and the number of turns of the screw can be reduced considerably, possibly up to a single turn. In this, generally called pulp

209882/0188 bathroom ORIGINAL

The procedure referred to as thickening, practically all of the liquid removal takes place in the filtration section. The helical surface section (pressing section) of the system works essentially as a throttle valve to increase the length of stay, to increase the filtration effect or to allow for use higher hydraulic pressure to give the suspension when this hydraulic pressure is the driving force Is the force that propels the liquid through the formed cake and filter net. Of course you can Outer housing of the Filtrationsabschnxtts vacuum can be applied to the driving force for the filtration raise.

The helical frexe shown at 16 in FIG Truncation is used when pressed fiber cakes with at least 25 percent dry fiber content are required and when maximum flexibility of the procedure is required. A change in the length of this non-screw surface Section in connection with the associated drainage section provide the required flexibility the capacity and a higher capacity of dehydration. This screw flat section can be omitted without affecting usability affect the overall system.

Those provided in the ejection section of the press "Fingers" or rods ti, which protrude into the pressed fiber cake, can, as shown at 17 in Fig. 1, be attached in a rigid position by screwing onto the discharge flange 3, or they can, as in Fig. 3 indicated, mounted on a rotatable shaft with a device for controlling this rotation

209882/0188

den, or you can leave them out in the entire complex, if they are dispensable with regard to the required end product. Generally speaking, these will Uses fingers whose task it is to slow down or stop the rotation of the emerging cake, because they increase the pressing capacity of the system and allow a higher spindle speed than without use such finger is possible. Rotatable fingers allow automatic control of the pressing capacity and the Consistency (percent of insoluble solids) of the final product discharged.

The system allows a construction in a vertical as well as in a horizontal position.

Claims;

209882/0188

Claims (1)

Claims 1.J Device for withdrawing liquid from a Suspension of fibrous solids in liquid, characterized by a housing (2) which has a filtration section and a pressing portion defined which are interconnected, which housing a Has means (5, 14) for dispensing liquid, through a cylindrical liquid-permeable filtration device (12) inside the housing, the liquid from the area inside the filtration device lets flow into the housing from which it is drained, through one in the cylindrical filtration device rotatable holder (10) arranged practically concentrically to it, by a number of scratches (11) in the filtration section, the scratches from the holder up to close to the inner surface of the cylindrical filtration device (12) and continue to remove a fiber mat that is formed on this inner surface and steer them towards the bracket so that they is mixed again with the suspension, through screw surfaces (F) in the pressing section of the housing, wherein the screw surfaces are directed from the holder in the direction of the filtration device are to press liquid from the suspension through the filtration device into the housing, and by a device (1) for feeding the suspension 209882/0188 sion into the filtration section. Device according to claim 1, characterized in that that the space between the filtration device and the housing in the filtration section opposes- ' is practically sealed over the corresponding space in the pressing section that a device for Applying vacuum to this space in the filtration section is connected and that the device for supplying the suspension, a device for applying a pressure above atmospheric pressure to the suspension in the interior of the filtration device in the filtration section. 3. Apparatus according to claim 1, characterized in that the rotatable holder in the filtration section has a diameter that is from the inlet end to the outlet end of the filtration section increases. 4. Apparatus according to claim 1, characterized in that the scratches with blades of curved surface are provided, extending from the vicinity of the filtration device in the direction of the rotatable Extend bracket. 5. Apparatus according to claim 1, characterized in that that the filtration device in the pressing section has the same diameter as the filtration device 209882/0188 direction in the filtration section and a continuation of this' filtration device, wherein the rotatable holder in the pressing section consists of a rotatable spindle, and that the screw surfaces, the spindle and the filtration device form an elongated zone with continuously decreasing Form cross-sectional area so that the liquid is pressed out of the suspension when it enters this zone happened. Device for removing liquid from a suspension of fibrous solids in liquid, characterized by a housing defining a pressing section and having means for dispensing is provided by liquid, through a liquid-permeable filtration device inside the housing, the liquid from the bar inside allows the filtration device to flow into the housing from which it is drained, by a rotatable filter arranged practically concentrically to it in the cylindrical filtration device Spindle, by screw surfaces attached to the spindle and are directed from it to the filtration device and serve to remove the suspension from the inlet end to convey the pressing section to its outlet end and to add liquid from the suspension pressing as it moves through the pressing section, further characterized in that at the discharge end of the pressing portion on the spindle a screw surface free Section is provided, the inner 209882/01 88 half of the filtration device lies and with this forms an annular zone, whereby a circularly pressed fiber cake around the screw surface-free Section is generated around next to the ejection end of the pressing section, and that the helical face-free Section of the spindle or the parts of the filtration device or the housing, which this screw surface-free section surrounded by the remaining spindle or filter device or the rest of the housing are separable. 7. Apparatus according to claim 6, characterized in that finger-like components protrude into the annular zone, to contact the annular pressed fiber cake and retard its rotation. Device for removing liquid from a suspension of fibrous solids in liquid, characterized by a housing defining a pressing section and having means for dispensing of liquid is provided by a cylindrical liquid-permeable filtration device inside the housing, the liquid from the area inside the filtration device into the Lets housing flow from which it is drained, through one in the cylindrical filtration device rotatable spindle arranged practically concentrically to it, by screw flats attached to the spindle and proceeding from it to the filtration device 209882/018 8 are directed and serve to convey the suspension from the inlet end of the press section to its outlet end and press liquid out of the suspension as it moves through the press section, further characterized in that at the ejection end of the press section on the spindle helicoid-free portion provided _r is seen that lies within the FiItrationseinrichtung and forms an annular zone therewith, whereby an annular pressed fiber cake is generated around the screw surface free portion around adjacent to the discharge end of the pressing portion, that further to the discharge end of the pressing portion a dilution section is connected and with that communicates in order to receive the pressed fiber cakes from it, this dilution section being practically closed against the entry of gas and having a device with which the dilution liquid can be introduced into the interior of the dilution section, and wherein f Furthermore, a stirring device is provided within the dilution section which breaks up the pressed fiber cake and mixes the dilution liquid with the fiber material so that the dilution liquid is sucked up by the fibers when the fiber material expands again due to the cessation of the pressure exerted on it in the pressing section, and finally a device for discharging the diluted fiber material from the dilution ζ one is provided » 9. Device for withdrawing liquid from a 209882/0188 Suspension of fibrous solids in liquid, characterized by a housing having a pressing section is defined and provided with a device for dispensing liquid "by a cylindrical liquid-permeable filtration device inside the housing, the liquid from the area within the filtration device allows it to flow into the housing from which it is drained will, by a rotatable filter arranged practically concentrically to it in the cylindrical filtration device Spindle, by screw surfaces attached to the spindle and are directed from it to the direction of filtration and serve to remove the suspension from To promote the inlet end of the pressing section to its outlet end and liquid from the suspension to press when it moves through the press section, ^ by finger-like components arranged at the ejection end of the pressing section and relative to the Spindle are movable, the finger-like components in the space between the spindle and the filtration device protrude in order to slow down the rotational movement of the pressed fiber cake and thus to increase the forces that the screw surfaces exert on the suspension exposed to compression, so that the liquid delivery is improved. 10. The device according to claim 9, characterized in that the .finger-like components fixed to the housing 209882/0188 are connected. 11. The device according to claim 9, characterized in that that the finger-like components are attached to a rotating shaft which is rotatable with respect to the spindle is and also opposite a brake assembly that is connected to the rotating shaft, to slow down their rotation adjustable. 12. The device according to claim 9, characterized by a rotatable holder which is relative to the spindle is rotatable, wherein the finger-like components are attached to the holder and relative to her let rotate to the spindle and wherein in an adjustable manner forces exerting means with the Bracket are connected to adjust their rotation speed '. 13. Device for removing liquid from a suspension of fibrous solids in liquid, characterized by a housing defining a pressing section and having means for dispensing of liquid is provided by a liquid-permeable Filtration device inside the housing, the liquid from the, area within the Filtration device can flow into the housing, from which she is drained, through one in the cylindrical filtration device practically concentrically arranged rotating 209882/0188 bare spindle, by screw surfaces attached to the spindle and are directed from her to the filtration device and serve to the To promote suspension from the inlet end of the pressing section to its outlet end and liquid out to press the suspension as it moves through the press section, by one connected to the press section Dilution section for taking over the pressed Fiber cake from the pressing section, this thinning section is closed against the access of gas and has a device with the dilution liquid in the interior of the Dilution section can be introduced, and further in the interior of the dilution section a Stirring device is provided which mixes the dilution liquid with the pressed fiber cake, so that the diluting liquid when the fiber material expands again from the fibers due to the cessation of the pressure exerted thereon in the pressing section is sucked up, and by means for discharging the diluted Fiber material from the thinning section. Device according to Claim 13, characterized in that it is dux'ch f ingerar tigei component «!, which is at the discharge end of the Preßabs chn it t; 3 are arranged, being, the fin ^ erart: igen Components in the barely /. Between the spindle and d'jr fi! Entered ion device protrude to the rotary movement to slow down the pressed fiber cake 209882/0 188 213Ü930 and thus to increase the forces that the screw surfaces exert on the suspension exposed to pressure exercise so that the liquid delivery is improved. 15. Device for withdrawing liquid from a ' Suspension of fibrous solids in liquid, characterized by a cylindrical drum made of a filtration mesh, behind which a perforated reinforcement part and its total length is chosen so that there is a retention time ^ which the fluid removal properties is adapted for the particular fibrous solids to be treated, wherein the liquid from the drum flows out through the drum openings while the moving forward fibrous material is retained in the drum; . by a solid drum surrounding the filtration mesh Filtration housing; by a concentric inside the filtration mesh drum ' to this arranged revolving spindle; wherein the filtration mesh drum has a filtration section defined in which the pulp suspension under hydraulic pressure is pumped, furthermore dtu Spindle diameter from the entry point dor Suspen-.sicm up to the outlet end of the filtration section increases, furthermore the spindle in the fi LLrat: L -.m »- absolmitt with a number of rotatable scratches Removal of the resulting fiber matta from d ^ ni cylindrical Metz is provided, which also dan cake convey into the area of the spindle and iliochung of the cake with the main part of the suspension 209882/0188 BAD ORDINAL lead, furthermore, the filtration housing from the rest of the device by flanges and through means for applying vacuum / is isolated to the filtration housing, further comprising the in pulp entering the filtration section low consistency in the range between about 2.0% ■ ■ fibrous solids and about 5.0% fibrous Solids and the suspension leaving the filtration section have a consistency between about 8.0 and 12.0% solids; by a pressing section consisting of a cylindrical Pressed mesh drum of the same diameter as the filtration mesh drum and which consists of the filtration section Receives leaving thickened suspension, the press screen drum in the press section is surrounded by a solid press housing made of metal for receiving the squeezed out liquid, wherein furthermore the rotating spindle inside the press mesh drum in the press section concentric to the drum runs, furthermore uninterrupted on the spindle Screw winding surfaces are attached, the slope of which from the entry end to close to the end of the exit end of the pressing section decreases, furthermore the screw thread surfaces on the suspension Applying forces that pull the liquid out of the suspension through the cylindrical press mesh drum through it outwards into the solid press housing, from where the liquid is carried away is, furthermore, the spindle has a short helical surface-free Section at the exit end of the press section and inside the cylindrical press screen drum possesses and finally the press cake 209882/01 88 - 144 - is ejected from the press section in the form of a pressed ring cake with a dry matter content in the range between about 15% and about 60 % ; by a number of rods with sharp edges protruding into the ring of the pressed pulp, which slow down the rotation of the pressed pulp and thereby increase the forces exerted by the helical surfaces against the pressurized suspension and improve the removal of liquid; by a closed dilution section for receiving the pressed cake, in which section there are mechanical stirrers which mix the cake with a dilution liquid while at the same time excluding air, so that the dilution liquid when the fiber material expands again due to the cessation of the pressure exerted on it in the pressing section, is soaked up by the fibers, sufficient amounts of additional liquid being added to the dilution section so that the diluted fiber mass can be discharged from the dilution station. 2 09882/0188 Hf Blank page