DD252982A5 - MULTI-STAGE DEVICE AND METHOD FOR COUNTERWASHING SUSPENDED SOLIDS - Google Patents

Abstract

The invention relates to a multi-stage apparatus and a method for countercurrent washing of suspended solids, preferably crystals, by means of series-connected hydrocyclone groups and associated pumps and pump suits. In order to be able to work with a relatively small apparatus-related effort when working under higher pressures and with higher temperatures in a certain, limited temperature range, the hydrocyclone groups, the pump sumps with projecting pumps and the essential parts or areas of the lines in a common, pressure-resistant and heat-insulated Container housed. Furthermore, for the purpose of eliminating larger crystallizations and solid particles, it is also possible to provide an upflow classifier likewise accommodated in the container. The invention further relates to applications of such an arrangement. For example, in a process for the preparation of terephthalic acid from dimethyl terephthalate as an intermediate and z. As in a process of coal hydrogenation. In addition, the invention relates to associated method measures. Fig. 2

Description

Field of application of the invention

The invention relates to a multi-stage device and a method for countercurrent washing suspended suspensions.

Characteristic of the known state of the art

Such arrangements are described in their basic structure and the associated mathematical foundations in "Process Engineering 8 (1974) Wr 1, page 28 - 31" and in "reprocessing technique Volume 18 (1977) page 395 - 404". They are also mentioned in DE-PS 30 44 617 concerning a process for the preparation of terephthalic acid from DimethylterepJatalat as an intermediate. Furthermore, a countercurrent washing system is specified in a further prior publication pertaining to the same method (DE-PS 29 1-6 197). With such a countercurrent washing, dissolved impurities are to be washed out. These impurities of the feed suspension are below the cut-off point of the hydrocyclone. The washing liquid used for washing them out can be of different types. For example, demineralized water is used for this purpose. One of the essential advantages of the hydrocyclones known for this purpose is that the solids present in the feed suspension are classified and supplied to the overflow or underflow according to their classification.

In a number of applications there is a requirement that must be carried out under elevated pressure and temperature, for process reasons-a certain temperature range must be maintained.

η 6.87- ^ 42-15:

_ 2 - Object of the invention

The aim of the invention is to avoid the high equipment expense of the known devices.

Explanation of the essence of the invention

The invention has the object to provide a multi-stage device and a method for countercurrent washing of suspended solids, in which the aforementioned conditions are solved with the least possible expense in terms of apparatus. In this respect, namely the above-mentioned prior art is not apparent.

To achieve this object, according to a preferred embodiment of the invention, all the essential parts of such a device and in particular the much larger part of the connecting line are arranged in the pressure-resistant and heat-insulated container. This serves, on the one hand, the safety of persons working with such an arrangement. The heat losses caused by heat radiation are very low. Sine alternative solution to the teaching of claim 2 is contained in claim 3. In both of the aforementioned embodiments, it is ensured, in particular, in connection with the content of claim 1, that the temperature in and at the components which are located in the container and the temperatures of the countercurrent washing are kept within the desired temperature range. Cold bridges to the outside are avoided, hole outside the container located parts or piping can be isolated and / or externally heated. The invention not only achieves the described functional advantages, but also creates a device of very compact and simple design from the container and the components located therein, which are particularly in the

preferred embodiment according to claim. 2 as an outwardly more compact, z. B .. cylindrical container with a few pipes presented. Since the components located within the container need not be isolated and are located within the container under elevated pressure, and therefore do not have to be made pressure-resistant on their own, advantageously, relatively low production costs result for the apparatus according to the invention. With regard to special and particularly advantageous applications of the invention, reference is made to the later statements on the claims 16 ff.

The features of claim 4 allow easy access to the hydrocyclones of the respective group for repairs or replacements by only 'the dome lid must be removed and lifted off with the hydrocyclones attached to it upwards. When speaking here in the majority of hydrocyclones, this is only for the sake of linguistic simplicity. However, this also includes the case in which only one hydrocyclone is present per group.

The features of claim 5 represent a preferred embodiment of the invention. They cause in addition to the intended isolation, a constant maintenance of the [temperature in the container. This is particularly recommended if the temperature range to be maintained in the container is very low (see comments on claims 16 and 17).

The features of claim 6 are used to compensate for thermal stresses.

The claims 7 to 11 are concerned with advantageous embodiments of the device, which have as far as possible accommodation of the various inlets and outlets in the container to the destination, on the other hand, the possibility

 include, against pressure and / or temperature sensitive components, such as the motors of the pumps and stirrers outside the container to provide (claims 7 to 9) · The configuration of the container and the housing of the hydrocyclone groups, pumps and sumps according to claims 10, 11 so chosen that the stages of the countercurrent washing system between the two end portions of the container are arranged in this one behind the other and the respective pump sump of the associated pump and hydrocyclone group directly associated, namely provided underneath.

The claims 12, 13 and 14 include advantageous derivations of the underflows of the hydrocyclone groups (claim 12) and the advancing hydrocyclone groups (claim 13) in the natural gradient and reducing and simplifying the lines and an arrangement of the components in the stages of the container, which required length of the pressure lines provided outside the container as far as possible reduced.

The features of claim 15 show that the level height in dejü. Pump sumps exactly the desired value, without the need for complicated control devices, radioactive measuring devices (Cesiumstrahler) and the like are necessary. Also known from other applications ago known float controls are avoided, which would clog easily with the here washed out solids, especially when it comes to auskristallisierende pesticides (see the comments on claims 16 and 17). The features of claim 15-act particularly advantageous together with the overflow arrangement according to claim 13.

Furthermore, the specific task of providing a countercurrent washing system for suspended solids in saturated solutions, to further crystallize the dissolved in the suspension of the pesticides on the one hand with certainty and on the other also with a, at pressures which are above the vapor pressure of the washing liquid at the working temperature To prevent reasonable equipment expense.

The achievement of this object are the features of claim 16. It is based on the finding that this proves to be particularly advantageous for the treatment of saturated solutions, ie so-suspended suspended - (crystals). In treating such solutions, it is crucial to avoid unwanted crystallization of additional particulate matter. This additional crystallization could, on the one hand, have the effect of more or less quickly clogging up pipes, container walls, barges, nozzles, etc., and, on the other hand, causing an impermissible crystallization even of "contaminants which are present, for example, in the purification of terephthalic acid (cf. Claims 17 "to 19) are contained in the solvent and are intended to be removed by the washing process. In order to avoid these disadvantages, it must be ensured that, in the case of counter-current washing, a drop below the vapor pressure belonging to the working temperature of the solvent in each pass is avoided. Such a shortfall could alone z. B. be conditioned by the suction of pumps. It would have a corresponding evaporation of the solvent with the consequence of the aforementioned crystallization to Polge. üies but is prevented according to the invention characterized in that the pump sump, is sucked from the inside of the pressurized container.

The same danger also exists if there is an inadmissible lowering of the working temperature of the countercurrent wash. The working temperature of the countercurrent wash is z. B. in the production of terephthalic acid described in more detail below according to the .DE-PS 30 44 617 due to. Solubility of Cokristallisationsneigung the impurities contained in the solvent (mother liquor). Such impurities have the tendency to crystallize on the pure terephthalic crystals. The working temperature is determined so that on the one hand the terephthalic acid is crystallized as nearly as possible, on the other hand, however, the impurities are still completely dissolved. A drop in temperature would, inevitably in turn, mean that in this case too the impurities would undesirably crystallize with the aforementioned consequences and, moreover, the aforementioned risk of blockage also occurs. -

The countercurrent washing according to the invention makes it possible with relatively little expenditure on equipment, at these relatively extreme requirements in terms of pressure and temperature still perfect results, d. H. to obtain a "washed" product with a minimum level of impurities. This is achieved by that. it allows this arrangement readily to work at a pressure which is above the aforementioned vapor pressure of the solvent at the operating temperature, so that the risk of improper evaporation can be clearly excluded.

Bine preferred application of the teaching of claim 16 results from claim 17. This has already been mentioned above. With regard to details of a possible and preferred process for the preparation of pure terephthalic acid from dimethyl terephthalate as an intermediate, the two cited above

DE-PS 29 16 197 and 30 44 617 referenced. The pesticides are terephthalic acid, the solvent (mother liquor) is water, the impurities are monomethyl terephthalate and the isomers of terephthalic acid and the washing liquid is dimineralized water. Instead of dimethyl terephthalate as an intermediate (claim 18) can be based on a further proposal of the invention of crude terephthalic acid as an intermediate (claim 19). Then the pesticide is likewise terephthalic acid, the solvents again water, acetic acid or mixtures thereof, the impurities are iaratu luallic acid, 4-carboxybenzaldehyde (4-cba) and the isomers of terephthalic acid, and all other impurities arising in oxidation and / or hydrogenation. In these two preferred cases one has to keep a temperature range of less than +1 C constant. Crystallization, z. B. by cold bridges, are to be avoided.

Furthermore, the teaching according to one or more of claims 1 to 15 can also be applied differently than specified in claims 16 and 17 and in the context explained in more detail above, the possibility of such an application is content of claim 20. Such coal hydrogenation is found high pressures and temperatures, so that for this purpose, too, the solution of the aforementioned object is essential for the success of such countercurrent washing.

There may be cases in which crystals, in particular the crystals of terephthalic acid, or pesticides of a ash-containing Peinstkohle (claim 20) in such a countercurrent washing system have an inadmissible, at least one undesirable size. It is therefore the other task to avoid this within such a countercurrent washing system.

To solve this problem, the features of claim 21 are initially provided. Upstream classifiers are for themselves, z. As for the separation of grain sizes in sands, known. However, when used in a counterflow apparatus according to the invention, they have the advantage that coarser crystals or particles of pesticide which are formed as a result can be removed. In addition, the claim 21 includes the further feature of accommodating the Aufstrpmklassierers in the common, pressure-resistant and thermally insulated container, so that the conditions mentioned at the outset to the hydrocyclones, etc. are also met with respect to the onstrom classier.

Claim 23 relates to the use of a. Upstream classifier for reducing the size of crystals of terephthalic acid, while claim 24 deals with the use of an upflow classifier for the removal of coarser crystals or pesticidal particles from a suspension.

The invention further relates to method measures according to claims 26 to 31 in order to control or regulate the processes, in particular the processes resulting from the use of the upstream classifier.

In particular, the multi-stage countercurrent washing device is that of suspended pesticides, preferably crystals, by means of. hydrocyclones connected in series or groups of several hydrocyclones connected in parallel (both hereinafter referred to simply as "Ilydrocyclone Group"), and associated pumps and sumps and lines connecting the aforementioned components, the scrubbing liquid flowing in countercurrent to the direction of conveyance suspended pesticides is promoted and wherein the suspended pesticides under increased pressure and

-s

Temperature treated, characterized in that the Kydrozyklongruppen and the pump sumps are housed therein with projecting pumps or pump parts in a common, druckiesten and thermally insulated container.

It is advantageous if the essential parts or areas of the lines are also housed in the common, pressure-resistant and heat-insulated container.

It may also be appropriate that essential parts or. Portions of the lines, or parts of the pump or pump lines provided outside the pressure-resistant and thermally insulated container and, if they lead to be kept within a certain temperature range media countercurrent washing, heat-insulated and / or externally heated.

The belonging to a stage Kydrozyklongruppe is arranged in a dome whose lid is removable and carries the associated hydrocyclone group, wherein the dome are pressure-resistant and thermally insulated.

It is advantageous that the walls of the container and optionally the dome are heated from the outside and the hydrocyclones or hydrocyclone groups in the domes on stretchable parts, for. B. bellows, are suspended.

The underflows and overflows of the hydrocyclone groups and their discharges to the pump sumps of the device are completely within the container or dome.

It may be advantageous that at least the pumps and partly the pump pressure lines are located outside the container, wherein the pump pressure lines are connected to the inlets of the next in the conveying direction of the suspended pesticides Hydrozyklongruppen.

Each pump sump is assigned a stirrer whose engine is outside the container.

Appropriately, in an elongated container in one end of the inlet of the suspended pesticides and the outgoing overflow of the washing liquid, and in the other end the addition of -vaschflüssigkeit and the outlet or outlet of the washed and thickened solid suspension is provided, which is connected in series between the end regions the steps of the counter-current washing system are located.

In the stages of the container are next to each other, d. H. in a plane extending approximately transversely to the longitudinal direction of the container, depending on a Hydrozyklongruppe or containing this hydrocyclone Dom and one pump with agitator, which is located in the lower part of each stage of the pump sump, which is separated by transverse walls of the respective adjacent pump sumps.

In this case, the underflow of the hydrocyclone group of each stage flows directly down into the pump sump below, while the overflow of the hydrocyclone group of each stage flows directly down into a channel, barge or the like, which is inclined and arranged so that they overflow in S 'Direction of the wash fluid in the natural gradient to the next pump sump or pump sump of the Y / ash liquid outlet flow.

In the sections or stages of the container, which are located one behind the other in the longitudinal direction thereof, the pumps and hydrocyclone groups are arranged on both sides of a vertical longitudinal center plane of the container, wherein a pump and a hydrocyclone group or the mandrel receiving them alternate in the longitudinal direction of the container.

are seen and in each case the pressure line of a pump is connected to the inlet of the adjacent in the conveying direction of the suspended pesticides Hydrozyklongruppe or Dom.

The height of the walls between the pump sumps in the conveying direction of the washing liquid decreases, thus allowing an overflow from a pump sump to the pump sump adjacent in this conveying direction,

In particular, the device is suitable for the following applications:

for the treatment of saturated solutions with crystallizing suspended pesticides to avoid acrystallization;

in a process for the production of pure terephthalic acid;

in a process for the production of pure. Terephthalic acid from dimethyl terephthalate as intermediate ¹ ;

in a process for the preparation of pure terephthalic acid from crude terephthalic acid as an intermediate;

- For the treatment of ash containing fine coal in the grain size preferably less than 1 mm containing hydrocarbon suspension, wherein water is provided as the washing liquid and the overflow in the form of suspended in hydrocarbon liquid further hydrogenatable Peinstkohlefraktion represents the desired product.

It is advantageous in the course of Gegenstromweschung a. Upstream classifier provided for the purpose of eliminating any crystallization and / or coarser solid particles, which is also housed in the common, pressure-resistant and thermally insulated container.

In this case, the lower portion of the upflow classifier is arranged in a dome, wherein the lid of the dome is removable and also this mandrel pressure-resistant and thermally insulated.

For use in a process for producing terephthalic acid, the upflow classifier is provided on the Singeng of the scrubbing liquid, and the clean scrub liquid inlet is connected to its upstream and forms the upflow of the classifier. The underflow of the associated hydrocyclone or hydrocyclone group located above it is fed to the inlet of the upstream classifier and the overflow of the upstream classifier flows into the associated pump sump and is passed on from there. The underflow of the power classifier is closed.

Purified by the treatment of saturated solutions with crystallized, suspended solid, or for the treatment of an ash-containing Peinstkoiile the Aufstromklassierer is provided in the container, preferably at the outlet of the contaminated washing liquid that its upflow is formed by a separately supplied quenching liquid, that the lower reaches of the associated, overlying hydrocyclone or hydrocyclone group is fed to the inlet of the upstream classifier, while the overflow of the upflow classifier flows into the associated pump sump and is forwarded from there and the underflow · the upstream classifier for the purpose of discharging the classified crystals or Schadstoffteilchen is opened.

(je, y '-j L, - 13 -

The stage lying in the direction of flow of the liquid at the bottom of the container is subdivided into two chambers or pump sumps, with each of these sumps having a separate underflow of the contaminated washing liquid, and the overflows of the hydrocyclone stages each being directed into the associated pump sump.

The method for Gegenstromv / ashes using the multi-stage device according to the invention is characterized in that the feed of washing liquid and the pump performance are coordinated so that always more feed than pump discharge and the amount of per unit time supplied and the up-stream forming clean wash liquid so is adjusted so that any crystallization of terephthalic acid are at least so far resolved that their size is equal to or less than a certain maximum size.

Advantageously, the amount of supply of the flow of liquid is regulated or controlled as a function of the particular suspension and its degree of impurity or the resulting crystallization.

By measuring the suspension density in the upflow classifier bed and a corresponding change in the volume of water, the degree of dissolution and / or the particle size to be separated off can be influenced.

Suitably, a control or regulation of the suspension supply is provided such that, with a constant grain size of the constituents of the suspension feed, a regulation of the suspension feed takes place as a function of its density.

- 14 - embodiments

For further details, reference is made to the following description and the accompanying drawings of. refer to the execution options according to the invention. In the drawing show:

 Pig. 1: the schematic flow diagram of the counterflow washing,

Pig. 2: the side view of an arrangement according to the invention, also schematically, with drawn components,

Pig. 3: a top view of pig. 2,.

Pig. 4: a section along the line A - Δ in Pig. 2,

Pig. 5: on an enlarged scale a section of the container wall,

Pig. 6: a Pließschaltbild analogous to the representation in the Pig. 1 and 2, but with omission of the plaque processes already shown there or

 Compounds, but with an upstream classifier used at the beginning of the feeding of the washing liquid,

Pig. 7: a section along the line VII - VII in Pig. 6

Pig. 8: a Pließschaltbild analog Pig. 6, but with the Aufstromklassierer in another location of the container and

y s 7 ν «- 15 -

Pig. 9: a diagrammatic representation of the pouring sequence of an arrangement according to FIG. 6 with a variant of the order of contaminated washing liquid. This Pließschaltbild applies mutatis mutandis to the execution of Pig. 8 with the proviso that the upflow classifier at the location according to Pig. 3 is provided.

First, using the Pig. 1, the conveying direction of Pließ-bzw. Current curves, etc. explained in the countercurrent washing system. You contaminated suspension passes through the line 1 and can be controlled by a valve 2 in dependence on the liquid level 3 of a sump 4 (precursor) by means of a schematically indicated device 5, the z. B. with radioactive rays, the level height 3 measures. In addition to the contaminated suspension, the overflow 7a of the next pump-on sump 4a is also conducted into the pump sump 4. The content of the pump sump 4 is fed via a pump 11 and a line 30 to the inlet 12a of the downstream in Pörderrrichtung P 1 of the suspension Ilydrozyklongruppe 9a. Their underflow 13 a passes into the associated pump sump 4a with agitator 6a. In the pumping direction P 2 of the washing liquid, the overflow 7b of the pump sump 4b following in the conveying direction P 1 and the overflow Sc of the after-cycle Eydrozyklongruppe 9c in the conveying direction P 1 lead into this pump sump 4 a. This continues in accordance with the individual from liydrozyklongruppen, pump sumps with pumps and ilührweric existing stages of the countercurrent washing system, wherein gradually the suspension repeatedly thickened and thus more and more purified until it finally flows out of the pump sump 4f last stage at 14. The washing liquid is added at 15 in the flow direction P 2 and flows through the weirs 7 a to 7 e. At 1o a Piltrat can be entered. In addition, in the free Pail the overflows of the pump sumps 4f, 4e, etc., according to the numbers 7f, 7e us? /, Flow in the

2 b Ί ν ö *

Pörderrichtung P 2. As well as the components discussed above, the underflow of the liydrozyklongruppen 9a, 9b, etc. with 13a, 13b, etc. and their overflows with 3a, 86, etc. numbered. They flow into the respectively underlying pump sumps 4a, 4b, etc. In the sumps the mixing of thickened cyclone underflow and the introduced overflow takes place.

The one in Pig. 1 left area includes not only the initially mentioned suspension feed 1, but. also the removal, d. H. the underflow 17 of the contaminated washing liquid from a pump sump 40 into which the overflows 8a and 8b of the two in the conveying direction Ϊ 1 nearest hydrocyclone stages open. The other, in Pig. 1 Binding area on the right contains the already explained removal 14 of the purified and thickened suspension and the above mentioned. Supply lines 15, 16.

The one in the Pig. 1 explained elements of this countercurrent washing system are in the Pig. 2 to 4 with the same numbers. These elements essentially surrounding 'container 13 is pressure-resistant and thermally insulated. When using the arrangement according to the invention can, for. B. pressures in the order of 75 bar and temperatures in the order of 300 C occur. This information is given only for example, without the invention being limited thereto. Each. Hydro cyclic ongruppe 9 is arranged in this preferred embodiment in a dome, which consists of a fixed to the container 18 lower part 19 a to 19 f and a detachably connected, preferably flanged top (cover) 20 a to 20 f. After loosening the flange connection and possibly the supply line 12, the respective Domoberteil 20a to 2Of with the hanging hanging Eydrozyklonen up for the purpose of A exchange or repair of Hydrozykone

lifted and then subsequently put back on the respective mandrel part 19a to 19f and thus firmly connected.

Fig. 5 shows "on an enlarged scale a section of the container wall and the peripheral wall, consisting of an inner protective layer 21, eg of stainless steel 1.4571 or titanium or another corrosion-resistant material." DIN 1.4571 is an internationally known designation an austenitic steel with the analysis: Si 1.0, Mn 2.0, P 0.045, S 0.030, Cr 16.50-18.50, Mo 2.00-2.50, Ήί 11.00-14.00, and G = In the case of a carbon content of less than 0.03, such a steel is stabilized, otherwise it must be stabilized by, for example, titanium .. Basically Crom-lJickel steels of the 2yp X 10 Gr ITi 18 8 with austenitic Similar and corrosion-equivalent steels are known under the US designation 316 L. However, the above information is meant only by way of example, without the invention being limited thereto, to which the inner protective layer 21 adjoins the supporting steel jacket 22. This is followed in the direction outward, an air gap 23 in which held by webs 24 heating 25 »z. B. steam flowed through pipes, is located .. 26 is the insulating layer located on the outside. Heating and insulation are coordinated.

From Pig. 2 and also from the contrast drawn on a larger scale Pig. 4 shows that the lower courses 13a to 13f and the overflows 8a to Sf of the hydrocyclone groups and their derivatives to. the sumps 4 to 4f are completely within the container 18 or the dome 19a to 19f, 20a to 2Of. The lower courses 13a to 13f flow directly into the pump sumps 4a to 4f underneath. The overflows of the Kydrozyklongruppen flow in

including gutters, barges or the like 2, a to 27f, which are functionally connected to the lines Sa to 8f of the Pig. 1 correspond. These grooves, barges or the like are sloping sloping in the conveying direction F 2 and arranged so that they overflow the hydrocyclone groups in this direction of the washing liquid in the natural gradient either through the gutters, barges or the like 27 b to 27 f in the second pump sump Case of the channel, barge or the like 27a flow into the pump sump 40 of the left in Fig. 2 area. The individual pump sumps 4 to 4f are separated from one another by partitions 28f to 28a, whereby in the conveying direction F 2 these partitions each become slightly lower.

If it is further ensured that the inlet of washing liquid 15 and the respective pump capacity are coordinated so that always the inlet is greater than the pump outlet, the pump sumps are always filled to the edge of lying in the conveying direction F 2 of the washing liquid partition wall 28, d. H. the height level of the swamps is always adjusted to a constant value. The overflowing liquid flows according to the line information 7f to 7a in the conveying direction F 2 from one sump to the next. Float controls or the like are, as mentioned, not necessary. The partition wall 28o between the pump sumps 4 and 4o is, however, deliberately made higher, since at this point no overflow should take place. For the above reasons, idling of the pumps is avoided. The drive motors of the pumps 11 to 11f and 29 to 29f of the agitators are preferably located outside the container, so that they are not attacked by the high pressure present in the container interior and the high temperature given there. The pumps can either be designed as submersible pumps and thus be provided completely inside the container 18.

the. It would also be possible to provide a part of the pump on the outside of the container and to heat it there, with the remaining parts of the pump projecting into the container, namely into the associated pump sump.

The pig. 2, 3 further show that the pump pressure lines 30 to 30e. are connected to the inlets of the next in the conveying direction F 1 of the suspended solids hydrocyclone group. Also at this point it should be noted that to a hydrocyclone group either only one. single hydrocyclone or multiple hydrocyclones connected in parallel. The pump pressure lines are thermally insulated. Although according to claim 3, the lines provided outside the container and heated in order to avoid crystallization, z. B. externally heated, can be (not shown in the drawing), it is a preferred embodiment of the invention to keep the line sections lying outside the container as short as possible, so that they are located with the greater part of their length within the container. Furthermore, according to. Fig. 3, the arrangement be taken as followsi

On both sides of the vertical plane 31 extending in the longitudinal direction of the container 1, a pump and a hydrocyclone group are alternately arranged one behind the other. In each of the stages, ie approximately transversely to the direction of the longitudinal center plane 31, a pump and a hydrocyclone group side by side, wherein in Fig. 3 left of the hydrocyclone group of stage a pump and right of the pump stage e is still at f a hydrocyclone group. With this spatial arrangement, the required length of the pump pressure lines 30 to 30e is kept as low as possible. In the lower areas of these stages · are the already explained sumps. The pump shafts are numbered with 10.

Possible applications of the invention are already discussed in connection with claims 16 and 17. A further possible application of the invention, in which no saturated solution with crystallizing suspended solids is provided, is described below:

A hydrocarbon suspension containing ash-containing fine coal with a grain size of less than 1 mm is at high pressure (eg 60 bar) and high temperature (eg 200 ^° C.) with as little water as possible in countercurrent to that already described Method separately. The separation is carried out in the higher-ash and also specific heavier and coarser water-containing fraction (underflow) on the one hand and in the further hydrogenatable very fine coal fraction (overflow) on the other hand, which is suspended in the hydrocarbon-containing liquid. In this application, the overflow is the desired, ie desired product, while the underflow, namely the ash-rich coal product with some water, is the waste product.

This example thus shows, on the one hand, the countercurrent washing of non-crystalline solids and, on the other hand, that the arrangement according to the invention can be used so well that the overflows lead to the desired end product and the underflows to the waste product.

The schematic illustration of FIG. 6, with the details already explained, shows an upflow classifier 32 provided in the course of this countercurrent washing, namely in the pump sump 4e and below the hydrocyclone group 9e, that the inlet of the fresh Inlet at V / ash liquid 15 at the same time is the upstream water of this classifier. This classifier is, in particular

Pig. 7 shows, in ν? it ent contained within the container 18. As far as it still protrudes from the container 18, a pressure-resistant and heat-sealed mandrel 33, 34 is provided, wherein the removable dome portion 34 allows to introduce the upflow classifier through the nozzle 33 into the container 13, and remove it again.

The upflow 15 flows through a nozzle plate 35 and impinges on the thickened suspension 13 e of the lower reaches of the hydrocyclone group S. This thickened suspension emerges from the lower end of the underflow 13 e leading stub-like tube 37 according to the arrows 36 and from the upflow 38 after torn up and through the upflow classifier bed 39 in the form of an annulus located between the classifier outer wall 40 and its tube 37, to the overflow 41 of the upstream classifier. As far as it is the application in a process for the preparation of terephthalic acid, the baw. to coarse crystals of terephthalic acid are dissolved by the upflow so far and thus reduced in size until the desired or permissible Llaximalgröße is reached. This can be z. B. be a Aristallgröße of 250 μ . The crystals of the desired reduced size then go over the overflow edges according to the arrows 42 in the sump 4e, from there to the next pump sump, etc., as it is based on the Pig. 1, 2 has been explained in detail. In the aforementioned application of the preparation of terephthalic acid, the upflow classifier must be arranged within the countercurrent washing plant (see eg Pig.6) so that the upflow of fresh, not yet contaminated scrubbing liquid is formed. Otherwise, the desired emaciation of coarser crystals would not be achieved or only very imperfectly. Even if the essential part of the coarse crystals of terephthalic acid is emaciated as described above and discharged upward with the upflow, so

After all, a discharge or outlet 43 must be provided on the upstream classifier.

In fact, the upflow water, and thus the solubility and desired crystal reduction, can not always be kept in exact equilibrium. It must therefore be possible to remove too coarse crystals through the outlet 43. It should be mentioned that the emaciation of the crystals of terephthalic acid must be done with fresh, unsaturated water, otherwise the effect of dissolution or emaciation of these crystals is not achieved.

If, in other applications, crystals are or form in the suspension, or 'solid particles are present which may interfere with their size but can not be dissolved, these crystals or solid particles may also be removed by means of an upflow classifier. This shows das.Das embodiment of FIG. 8, wherein the section VII'-VII · practically corresponds to the section VII-VII of FIG. 6 and thus of FIG. Again, the discharge opening 43 is provided for the discharge of ausschecheidenden crystals or solid particles. IJur it is not necessary here to use fresh, unsaturated upstream water. The upflow classifier can therefore be provided at any point in the flow sequence in the container 18, z. B. as Fig. 8 shows in the pump sump 4c. In this application, there is no dissolution or emaciation of crystals, but only a classification of too coarse particles or grains, which can also be done by a contaminated liquid. But it is also preferred for a ^ lassiierung the upflow classifier in the sump 4e, d. H. Provide at the point at which fresh washing liquid is supplied. By largely using the numbering of FIG. 7, the function of the upstream classifier in the embodiment of FIG. 8 is explained as follows:.

  - 23 -

At 45 upstream water is supplied. From the hydrocyclone group 9c of the underflow 13c flows into the pipe socket 37 and is detected after the exit at the lower Rohrstutzehende from on stream 38, wherein the classification takes place, iiur in this example, the too large or coarse crystals or Peststoffteilchen not partially dissolved, but fall down through and exit through the discharge port 43. The overflow 42 passes into the sump 4c where the upflow classifier is located. Incidentally, the course of countercurrent washing as based on the Pig. 1, 2 described. The various possibilities of arranging the upstream classifier in the container 18 have already been explained above. When it comes to removing coarse particles from a ashy charcoal by classification, it is recommended to use it as far as possible at the exit side of the scrubbing liquid, ie. H. preferably in the sump 4a provide.

The hydrocyclone group can be suspended by a bellows 44 elastically in the lid (2Oe or 20 c) of the respective Domes. This has the advantage that this allows Vjärrae- voltages absorbed or compensated. This bellows or other elastic expansion piece holds the hydrocyclone vertoiler. In addition, through such a bellows, an access (pipe) can be made to the distributor.

For control or regulation is also pointed out that one can influence the degree of dissolution and / or the particle size of the suspension to be separated by measuring the suspension density in the upstream classifier bed 39 (see Pig. 7) and a corresponding change in the Aufstromwassermenge.

In order to achieve a uniform grain size in the final product, it is sufficient in the pail to have a constant grain size of 1.

suspension control the suspension feed as a function of the density of this suspension, which can be measured. ,

Pig. 8 also shows a suction pipe 46 "which is attached to each of the pumps (here pump 11b) (not shown in detail.). This line serves to be able to pump the suspension from the sump even at low liquid level.

£ 'ig. FIG. 9 shows a flow diagram of the embodiment according to FIG. 6 for a better understanding, wherein essentially the illustration and in particular also the numbering of FIG. 1 has been adopted. Pig. 9 also shows the variant of two separate lower runs 17 a and 17 b of the contaminated liquor.

The examples of Pig '. FIGS. 6 to 9 further show that in stage 0, the chamber or sump 4o may be subdivided into two chambers or sumps 4.o a and 4. o b. Details of this distribution are in particular Pig. 9 and the corresponding numbering. Hereby one can separate the overflows 8a and 8b of the hydrocyclone stages 9a and 9b separately and thus supply them separately to different further processing stages. This may be advantageous because the overflows have different degrees of contamination. The overflow 8a is more contaminated than the overflow 8b. The overflow 8a of the hydrocyclone group 9a thus leads into the sump 4.0 a. This is associated with a separate underflow 17a. The overflow. 8b of the hydrocyclone group 9b, on the other hand, leads into the pump sump 4.0b, whose underflow of the contaminated scrubbing liquid is numbered 17b.

In general, for all embodiments to say that fed at 15 fresh washing liquid or washing water

must become. At 16, a diluent (PiI) may be added, if necessary, to make the suspension pumpable in the chamber 4f, i. H. to dilute accordingly.

If a classifier is provided, in the embodiment of the Pig. .6 the Aufströme liquid with the washing liquid identical. In contrast, in the example of the pig. 8 at 15, the supply of the washing liquid and at 45 the supply of a separate Aufstromflüssigkeit or on stromwassers.

All features shown and described, and their combinations with each other are essential to the invention.

Claims (25)

- 26 Pat en tans prüche 1 · Multi-stage apparatus for countercurrent washing · of suspended solids, preferably crystals, by means of hydrocyclones connected in series or of groups of several hydrocyclones connected in parallel (both hereinafter referred to simply as "hydrocyclone group ¹¹ ") and associated pumps and pump sumps and the conduits connecting the aforementioned components, the scrubbing liquid being conveyed countercurrently to the conveying direction of the suspended solids and the suspended solids being treated under elevated pressure and temperature, characterized in that the hydrocyclone groups (9a to 9f) and the sumps (4 to 4f) are housed therein with projecting pumps or pump parts in a common, pressure-resistant and heat-insulated container (18). 2. Apparatus according to claim 1, characterized in that the essential parts or areas of the lines are also housed in the common, pressure-resistant and thermally insulated container (18). Device according to claim 1, characterized in that substantial portions or lines of the pipes or ropes of the pumps or of the pump pipes are provided outside the flameproof and thermally insulated container (18) and, if they contain the media to be held within a certain temperature range Run countercurrent washing, heat-insulated and / or externally heated. 4. Device according to one of claims 1 to 3, characterized in that the to a stage (a to f) belonging to the hydrocyclone group (9a to 9f) in a dome (19a to 19f, 20 a to 2Of) is arranged, whose lid ( 20a to 2Of) and carries the associated hydrocyclone group, - 27 where the mandrels are flameproof and thermally insulated. 5. Device according, one of claims 1 to 4, characterized in that the V / andungen "of the container and optionally the dome from the outside are heated (2 5). 6. _orr V iclitung according to any one of claims 1 to 5, characterized in that the hydrocyclones BAW. Hydrozyklongrunpen (9a to 9f) in the Domen (19a to 13f) via stretchable parts, z. B. bellows (44) are suspended. 7. Device according to one of claims 1 to 6, characterized in that the underflow (13 a to, 13 f) and overflows (Sa to Sf) of the hydrocyclone groups (9 a to 9 f) and their derivatives to the pump sumps of the assembly is completely within the container (18) or the dome (19a to 19f), 20 a to 2Of) are located. 8. Device according to one of claims 1 to 7, characterized in that at least the IvIo tor en the pump (11 to 11e) and partially the pump pressure lines (30 to 3Oe) are outside the container (18), wherein the pump pressure lines with the feed (12a to 12f) of the next in the conveying direction (5 ¹ I) of the suspended pesticides hydrocyclone groups (9a to 9f) are connected. 9. Device according to one of claims 1 to 8, characterized in that each pump sump (4c to 4f) is associated with an agitator (6c to 6f), the - ^ otor (29c to 29f) is located outside of the container (18), 10.Vorrichtung according to any one of claims 1 to 9, characterized in that in an elongated container C13) in one hand, the inflow (1) of the suspended solids and the outgoing overflow (17) of the washing liquid, as well as in the other end Addition (15) of the V.aschfltissigkeit and the outlet or outlet (14) of the washed and thickened pesticide suspension are provided, which are connected in succession between the Sndbereichen the stages of the countercurrent washing system. 11. The device according to claim 10, characterized in that in the steps (a to e) of the container (18) side by side, d. H. in a plane extending approximately transversely to the longitudinal direction of the container, each one hydrocyclone group (9a to 9e) or the dome containing said hydrocyclone group and one pump (11 to 11e) with agitator (6a to 6e) are arranged, wherein in the lower part of each stage of Pump sump (4a to 4e), which is separated by transverse walls (28a to 2Sf) of the respective adjacent pump sumps. 12. The apparatus according to claim 11, characterized in that the underflow (13a to 13f) of the hydrocyclone group (9a to 9f) of each stage flows directly down into the underlying pump sump (4a to 4f). 13. The apparatus according to claim 11 or 12, characterized in that the overflow (8 a to 8 f) of the hydrocyclone group (9 a to 9 f) of each stage flows directly down into a channel, barge or the like (27 a to 27 f), the so inclined and is arranged to flow the overflow in Fö'rderrichtung (F 2) of the washing liquid in the natural gradient to the next pump sump or pump sump (4o) of the washing liquid outlet. 14. The device according to any one of claims 11 to 13, characterized in that in the sections or stages of the container (18) which are in the longitudinal direction one behind the other, the pumps (11 to 11e) and, hydrocyclone groups (9a to 9f) on both sides of a vertical The longitudinal center plane (31) of the container are arranged, wherein, the longitudinal direction of the container, alternately a pump and a hydrocyclone group or the receiving female are provided, and that in each case the pressure line (30 to 3Oe) a pump with the inlet (12a to 12f ) is connected in the conveying direction (P 1) of the suspended solids adjacent hydrocyclone group or dome. '. 15. Device according to one of claims 11 to 14, characterized in that the height of the 'partitions (28 a to 28 f) between the pump sumps in the conveying direction (P 2) of the; / a, liquid decreases and thus an overflow of a pump sump to the in this. Pörderrichtung (P 2) adjacent pump sump allows. .16. Device according to one of claims 1 to 16, characterized by its application for the treatment of saturated solutions with crystallized suspended solids, in order to avoid crystallization « 17. Device according to claim 16, characterized by its use in a process for the preparation of pure terephthalic acid. 18. The apparatus according to claim 17, characterized by its use in a process for the preparation of pure '.Terephthalsäure from dimethyl terephthalate as an intermediate. 19. The apparatus according to claim 17, characterized by its application in a process for the preparation of pure terephthalic acid from crude terephthalic acid as an intermediate. 20. Device according to one of claims 1 to 15, characterized by their application for the treatment of a ash-containing Peinstkohle in the grain size preferably small ner than 1 mm containing hydrocarbon suspension, which is provided as a washing liquid \ 7asser and the overflow in the form of suspended in hydrocarbon liquid further hydrogenated Feinstkohlefrcktion represents the desired product. 21. Device according to one of claims 1 to 20, characterized in that provided in the course of the countercurrent washing a Aufstromklassierer (32) for the purpose of eliminating any crystallizations and / or coarser solid particles and also in the common, pressure-resistant and wärmexso.lirrten container (18). is housed. The device according to claim 21, characterized in that the lower portion of the upstream classifier (32) is disposed in a dome (33, 34), the dome (34) of the dome being detachable and also that dome (33, 34) pressure-resistant and thermally insulated. .23 Device according to one of claims 17 to 19, 21, 22, characterized in that for the application in a process for the production of terephthalic acid the upflow classifier (32) at the entrance of the washing liquid (15) is provided that the influx of the sowable Washing liquid (15) is connected to the Aufströmöffnung and forms the upflow of the classifier, that the lower reaches (13 e) of the associated, located above hydro cyclone or Iiydrozyklongruppe (9e) is fed to the inlet of the Aufströmeklassierers, that the overflow (42) of Stream classifier in the associated pump sump (4e) flows and is forwarded from there and that the lower reaches (43) of the power class classified. is closed. 24. v'orricirtung according to any one of claims 16, 20 to 22, characterized in that for the treatment of saturated solutions with crystallizing suspended solids, or for the treatment of ash-containing fines coal of the upflow classifier (32) in the container preferably at the outlet of the contaminated Washing liquid is provided that its upflow is formed by a separately supplied washing liquid (45), that the lower reaches of the associated, overlying hydrocyclone or hydrosyclone group is fed to the inlet of Aufstroniklassierer's that the overflow of Aufstromklassierers flows into the associated pump sump and from there is forwarded and that the underflow (43) of the upstream classifier for the purpose of discharging the classified crystals or Schädstoffteilchen is opened. 25. Device according to one of claims 1 to 24, characterized in that the lying in the flow direction of the washing liquid at the end of the container stage (o) is divided into two chambers or pump sumps (4.ο a and 4.0 b), wherein each This pump sumps a separate underflow (17a, 17b) of the contaminated scrubbing liquid belongs and that the overflows (Sa and 8b) of the hydrocyclone stages (9a, 9b) each in.den associated pump sump (4.ο a and 4.ο b) are passed , 26. A process for countercurrent washing of suspended pesticides, characterized in that the inlet of washing liquid and the pump performance are matched to one another such that always more inlet than the pump outlet. 27. The method according to claim 26, characterized in that the amount of supplied per unit time and the 2 5 2 9 8 Upstream forming clean wash liquid is adjusted so that any crystallizations of terephthalic acid are at least so far resolved that their size is equal to or less than a certain maximum size. 28. The method according to claim 26 and 27, characterized in that the supply amount of upflow liquid is regulated or controlled in dependence on the respective suspension and the degree of impurity or the resulting crystallization there. Process according to Claims 26 to 28, characterized in that the degree of dissolution and / or the particle size to be separated are influenced by measuring the suspension density in the air flow classifier bed (39) and a corresponding change in the amount of wash water. 30. The method according to claim 26 to 28, characterized by a regulation or control of the suspension feed. 31. The method according to claim 30, 'characterized in that with a constant grain size of the components of the suspension supply, a regulation of the suspension supply in dependence on their density. Hkr Iu. S Se ^ tOz 2t> ch