EP1748269B1 - Rotary furnace for manufacturing activated carbon - Google Patents

Description

The present invention relates to a rotary tube, in particular for a rotary kiln for the production of activated carbon, according to the preamble of claim 1 and a rotary kiln with such a rotary tube. Furthermore, the present invention relates to the use of this rotary tube or rotary kiln for the production of activated carbon.

Activated carbon is the most widely used adsorbent due to its rather nonspecific adsorptive properties. Legal requirements, but also the increasing awareness of the responsibility for the environment, lead to an increasing need for activated carbon.

The activated carbon is increasingly being used both in the civilian as well as in the military field. In the civil sector, activated carbon is used, for example, for the purification of gases, filter systems for air conditioning, car filters, etc., while in the military area the activated carbon is used in protective materials of all kinds (eg respirators, protective covers and protective clothing of all kinds, such as eg protective suits etc.)

Activated carbon is generally obtained by carbonation (also referred to synonymously as carbonization, pyrolysis or coking) and subsequent activation of suitable carbonaceous starting materials. In this case, those starting materials are preferred which lead to economically reasonable yields. Because the weight loss by elimination of volatile components in the carbonization and by the burn-off when activating are significant. For further details on the production of activated carbon, reference can be made, for example, to H. v. Chem. Kienle and E. Baths, activated carbon and their industrial application, Enke Verlag Stuttgart, 1980.

The nature of the activated carbon produced - fine or coarsely porous, solid or brittle, etc. - depends on the carbonaceous starting material. Typical starting materials are, for example, coconut shells, wood waste, peat, hard coal, pitches, but also special plastics such. As sulfonated polymers that play a major role in the production of activated carbon in the form of granules or beads, inter alia.

Activated carbon is used in various forms: powdered coal, chipping coal, grain carbon, carbon and since the late 1970s also grain and spherical activated carbon (so-called "coal" or "carbon"). Grain-shaped, in particular spherical activated carbon has over a number of advantages over other forms of activated carbon such as powder, chipping coal and the like, which makes them valuable or even indispensable for certain applications: it is free-flowing, highly abrasion-resistant and dust-free and very hard. Grain, especially ball coal, because of their special shape, but also because of the extremely high abrasion resistance for special applications, such. As surface filter materials for protective suits against chemical toxins or filters for low pollutant concentrations in large quantities of air, very popular.

In the production of activated carbon, in particular granular carbon and spherical carbon, it is assumed in most cases of suitable polymers. Preference is given to using sulfonated polymers, in particular sulfonated divinylbenzene crosslinked styrene polymers, wherein the sulfonation can also be achieved in situ in the presence of sulfuric acid or oleum. As a suitable starting material serve z. B. ion exchange resins or their precursors, which is usually divinylbenzene crosslinked polystyrene resins, wherein in the case of the finished ion exchanger, the sulfonic acid groups are already present in the material and in the case of Ionenaustauschervorstufen still need to be introduced by sulfonation. The sulfonic acid groups play a crucial role as they play the role of a crosslinker by cleavage during carbonation. Disadvantageous and problematic, however, are in particular the large amounts of sulfur dioxide released and, among other things, the associated corrosion problems in the production equipment.

Usually, the production of activated carbon takes place in rotary kilns. These have, for example, a point of entry for the raw material feed at the beginning of the oven and a discharge point for the end product at the end of the oven.

In the conventional processes for producing activated carbon according to the prior art, in the batchwise production, both the carbonization and the subsequent activation are carried out in a rotary kiln.

In carbonization, which may precede a pre-carbonization phase, the conversion of the carbonaceous feedstock to carbon occurs, in other words, the feedstock is charred. In the carbonization of the aforementioned organic polymers based on styrene and divinylbenzene, the crosslinking functional chemical groups which in their thermal decomposition to free radicals and thus lead to crosslinking, in particular sulfonic acid groups, are - with elimination of volatile components, in particular SO ₂ - destroys the functional chemical groups, in particular sulfonic acid groups, and free radicals form, which cause strong crosslinking - without which there would be no pyrolysis residue (= carbon). Suitable starting polymers of the abovementioned type are, in particular, ion exchange resins (for example cation exchange resins or acidic ion exchange resins, preferably with sulfonic acid groups, for example cation exchange resins based on sulfonated styrene / divinylbenzene copolymers) or their precursors (ie the unsulfonated ion exchange resins which are present or in the carbonation still with a suitable sulfonating agent, such as sulfuric acid and / or oleum, must be sulfonated). In general, the pyrolysis is carried out under an inert atmosphere (eg nitrogen) or at best a slightly oxidizing atmosphere. Similarly, during carbonation, especially at higher temperatures (eg, in the range of about 500 ° C to 650 ° C), it may be advantageous to add a smaller amount of oxygen to the inert atmosphere, particularly in the form of air (e.g. 1 to 5%) to effect oxidation of the carbonized polymer skeleton and thus facilitate subsequent activation.

Due to the acidic reaction products (eg SO ₂ ) removed during the carbonation, this stage of the activated carbon production process is extremely corrosive with respect to the furnace material and places the highest demands on the corrosion resistance of the rotary kiln material.

Carbonation is then followed by activation of the carbonated starting material. The basic principle of activation is to selectively and selectively degrade part of the carbon generated during carbonization under suitable conditions. This creates numerous pores, Crevices and cracks, and the unit mass surface of the activated carbon increases significantly. During activation, a targeted burning of the coal is thus carried out. Since carbon is degraded upon activation, this process results in a sometimes considerable loss of substance which, under optimum conditions, is equivalent to an increase in porosity and an increase in the internal surface area (pore volume) of the activated carbon. The activation therefore takes place under selective or controlled oxidizing conditions. Common activating gases are generally oxygen, in particular in the form of air, water vapor and / or carbon dioxide and mixtures of these activating gases. If desired, inert gases (eg nitrogen) may be used in the activation gases. In order to achieve a technically sufficiently high reaction rate, the activation is generally carried out at relatively high temperatures, in particular in the temperature range from 700 ° C to 1200 ° C, preferably 800 ° C to 1100 ° C. This places high demands on the temperature resistance of the Trohrohrofenmaterials.

Since the rotary kiln material must withstand the very corrosive conditions of the carbonation phase as well as the high temperature conditions of the activation phase on the one hand, only those materials are used for the production of the rotary kiln, which have a good high temperature corrosion resistance, d. H. in particular steels, which combine a good resistance to chemically aggressive materials, in particular a good corrosion resistance, as well as a good high temperature resistance in a single material.

Despite the high temperature resistance of the materials commonly used for the rotary kiln, especially steel, the high operating temperatures in activated carbon production, which can reach up to 1200 ° C or even more, make these materials or steel relatively soft under these extreme temperatures and lose shape stability and, as a result, tend to have some susceptibility to mechanical deformation. Process inherent occur in the active production of strong pressure differences and pressure fluctuations: This is due in particular to the fact that on the one hand gaseous degradation products are generated and on the other hand reaction or process gases must be supplied and operating under changing pressure conditions (eg atmospheric pressure and reduced pressure or vacuum), wherein the pressure conditions can not be kept constant over the entire process time of the activated carbon production. This leads in part to the fact that the not insignificant pressure differences and pressure fluctuations in the operating state can cause a deformation of the rotary tube. This can lead to damage to the rotary kiln and premature material fatigue, and on the other hand, the process control and process control are not significantly hampered.

It is therefore an object of the present invention to provide an apparatus or a rotary tube which is particularly suitable for the production of activated carbon, wherein the previously described disadvantages of the prior art are at least partially avoided or at least mitigated should.

To solve the above problem, the present invention proposes a rotary tube according to claim 1. Further, advantageous embodiments are the subject of the relevant subclaims.

Another object of the present invention is a rotary kiln according to claim 11, which comprises the rotary tube according to the present invention.

Finally, another object of the present invention is the use of the rotary tube or rotary kiln according to the invention for the production of activated carbon according to claim 12. Further, advantageous embodiments of the inventive use are the subject of the use subclaim.

The present invention - according to a first aspect of the present invention - is thus a rotary tube, in particular for a rotary kiln for the production of activated carbon, wherein the rotary tube is provided on the outside with at least one reinforcing element for stabilizing the rotary tube in the operating state. Thus, a rotary tube is provided with reinforcing elements, which is dimensionally stable in the operating state, in particular under extreme temperature conditions and has a high resistance to deformation.

The Applicant has surprisingly found that the mechanical stability or the dimensional stability of the rotary tube in the operating state, especially under extreme conditions (such as occur in activated carbon production, for example), can be considerably improved if the rotary tube on its outside or Outside wall is provided with at least one reinforcing element, preferably with a plurality of reinforcing elements.

In this way, a rotary tube is provided which can better resist mechanical deformation and is more resistant to strong pressure differences and pressure fluctuations and thus is dimensionally stable under operating conditions. The rotary tube according to the invention consequently has an improved service life with a reduced tendency for premature material fatigue. As a result, the process control and process control are facilitated.

Fig. 1

eine schematische Seitenansicht eines Drehrohrofens nach einem bevorzugten Ausführungsbeispiel der vorliegenden Erfindung im Schnitt (Fig. 1) sowie Ausschnitte a), b), c) und d) von verschieden ausgebildeten, erfindungsgemäß bevorzugten Ausgestaltungen der Verstärkungselemente;

Fig. 2A

einen radialen Querschnitt durch das Drehrohr;

Fig. 2B

einen vergrößerten Ausschnitt des in Fig. 2A gekennzeichneten Bereiches;

Fig. 3A - C

eine schematische Darstellung von Profilen von Mischelementen mit unterschiedlich ausgebildeten Befestigungsabschnitten sowie eine schematische Darstellung der Verstärkungselemente.

Further advantages, features, aspects, features and features of the present invention will become apparent from the following description of a preferred embodiment shown in the drawing. It shows:

Fig. 1

a schematic side view of a rotary kiln according to a preferred embodiment of the present invention in section ( Fig. 1 ) as well as sections a), b), c) and d) of differently shaped, according to the invention preferred embodiments of the reinforcing elements;

Fig. 2A

a radial cross section through the rotary tube;

Fig. 2B

an enlarged section of the in Fig. 2A marked area;

FIGS. 3A-C

a schematic representation of profiles of mixing elements with differently shaped mounting portions and a schematic representation of the reinforcing elements.

Fig. 1 . 2A, 2B and FIGS. 3A to 3C show a rotary tube 1 according to the present invention which can be used in a rotary kiln for the production of activated carbon. As can be seen from the figures, the rotary tube 1 according to the invention is provided on the outside with at least one reinforcing element 8 for stabilizing the rotary tube 1 in the operating state.

Like that Fig. 1 . 2A, 2B 3A and 3C, furthermore, mixing elements 3 for the circulation or mixing of loading material 4 located in the interior 2 of the rotary tube 1 can be arranged in the interior 2 of the rotary tube 1. According to the invention, the mixing elements 3 may be, for example, circulating or turning sheets, which are also referred to as material guide sheets, synonymously. The rotary tube 1 may have openings 5, which serve to receive fastening sections 6 of the mixing elements 3. The fastening sections 6 of the mixing elements 3 are preferably welded to the rotary tube 1 on the outside. In other words, it may be provided according to the invention that the mixing elements 3 pass through the rotary tube 1 radially and in particular are welded to the rotary tube 1 on the outside or on the outside.

As such, the rotary tube 1 can be designed in particular as shown in the DE 10 2004 036 109.6 of 24 July 2004 is described, the entire disclosure of which is hereby incorporated by reference.

Also US 2939693 or DE 914 718 described a fixed rotary tube by externally welded reinforcing elements.

As far as the reinforcing element 8 is concerned, this serves for the mechanical stabilization of the rotary tube 1, in particular when it is exposed in the operating state to high temperatures and strong pressure fluctuations or pressure differences. In this way, due to the inventive equipment of the rotary tube 1 with at least one reinforcing element 8 is compared to the prior art significantly improved dimensional stability or resistance of the rotary tube 1 against deformation, especially in the operating state guaranteed.

The reinforcing element 8 may be formed such that the rotary tube 1 is stabilized in its cross section and / or in its longitudinal extent. As in the Fig. 1 2A and 2B, the reinforcing member 8 may extend peripherally around the rotary tube 1. In this case, the reinforcing element 8, for example, perpendicular or inclined to the axis of rotation of the Rotary tube 1 extend, whereby a gain or stabilization of the cross section of the rotary tube 1 is realized. As far as the term "peripheral" is concerned, this refers to a circumferential arrangement of the reinforcing element 8 on the outer or outer wall of the rotary tube 1.

As regards the arrangement of the reinforcing element 8, this is arranged according to a preferred embodiment according to the invention coaxial with the rotary tube 1, such as Fig. 1 and 2A demonstrate. Thus, the reinforcing member 8 and the rotary tube 1 are arranged concentrically with each other in the cross-sectional area.

Furthermore, the detail enlargements a) to d) of Fig. 1 such as Fig. 2A in that the reinforcing element 8 preferably extends at least substantially completely over the circumference of the rotary tube 1. Equally, however, it is also possible in the context of the present invention that the reinforcing element 8 extends in sections, for example in segments, over the circumference of the rotary tube 1.

Fig. 1 and Fig. 2A show that the reinforcing element 8 is formed in accordance with a ring according to the invention particularly preferred embodiment. In this case, the reinforcing element 8 may be formed, for example, as an annular flange or in the manner of a hollow cylinder. In order to ensure a tight and the rotary tube 1 stabilizing concern of the reinforcing element 8 on the outer wall of the rotary tube 1, while the inner diameter of the reinforcing element 8 should at least substantially correspond to the outer diameter of the rotary tube 1.

The present invention is not limited to a ring or hollow cylindrical design of the reinforcing element 8. Thus, for example, it may also be provided that the reinforcing element 8 is rib-like or helical. In a helical formation of the reinforcing element 8, the reinforcing element 8 extends in a manner helical in the longitudinal direction of the rotary tube 1 around its circumference; Also in this embodiment, not shown in the figures, the reinforcing element 8 and the rotary tube 1 can be coaxial with each other or arranged.

According to a further embodiment of the invention, the reinforcing element 8 may extend axially along the rotary tube 1, whereby in particular a stabilization of the rotary tube 1 is achieved in its longitudinal extent. In this case, the reinforcing element 8 can extend in particular over the entire length of the rotary tube 1. As regards the axial arrangement of the reinforcing element 8, the reinforcing element 8 can be arranged on the outer wall of the rotary tube 1 in this embodiment, not shown in the figures, for example, parallel to the rotational or longitudinal axis of the rotary tube 1.

As Fig. 1 such as Figs. 3A, 3B and 3C show, the reinforcing element 8 as such z. B. an at least substantially rectangular cross section, wherein the cross section of the reinforcing element 8 refers to the cut surface according to a section in the radial plane of the reinforcing element 8. The height or width of the cross section of the reinforcing element 8 can vary within wide limits. According to the invention, the height and width of the cross section of the reinforcing element 8 can be, for example, 0.5 cm to 10 cm, preferably 0.5 cm to 8 cm, preferably 1 cm to 6 cm, particularly preferably 1 cm to 5 cm. According to the invention, the cross section z. B. square, but it is equally possible and preferred according to the invention that the height and the width of the cross section of the reinforcing element 8 are different. It is preferred that the height of the cross section of the reinforcing element 8 is greater than its width. According to the invention, however, it is also possible in principle that the cross section of the reinforcing element 8 is at least substantially circular or round, for example in the manner of a circularly closed steel wire.

Preferably, according to the invention, the reinforcing element 8 is welded to the rotary tube 1 via a welded connection 9, as in FIGS Fig. 1 . 2A, 2B and 3A to 3C can be seen. As a result, a permanent connection between the reinforcing element 8 on the one hand and the rotary tube 1 on the other hand guaranteed. According to a preferred embodiment according to the invention, the welded joint 9 extends along a line of contact of the reinforcing element 8 with the rotary tube 1 without interruption, as shown in particular in the detail enlargements a) to d) Fig. 1 as in Fig. 2A you can see.

Alternatively, however, a section-wise or segment-like welded joint 9 of the reinforcing element 8 with the rotary tube 1 or a punctiform formation of the welded joint 9 for permanent attachment of the reinforcing element 8 on the rotary tube 1 is possible.

According to the invention it can be provided that the welded joint 9 has at least two welding layers 9a, 9b, as shown in FIG Fig. 2B and the section enlargement according to Fig. 3A you can see. In this way, so to speak, a double welded joint 9 with welding layers 9a, 9b is formed. Different materials can be used for the different welding layers 9a, 9b. For related embodiments, reference may be made to the following explanations concerning the welding of the fastening sections 6 of the mixing elements 3 to the rotary tube 1.

Further types of connection between the reinforcing element 8 on the one hand and the rotary tube 1 are well known to those skilled in the art: For this purpose, for example, screwing, riveting and the like can be cited. According to the invention, however, such a connection between reinforcing element 8 and rotary tube 1 is preferred, which does not pierce the shell of the rotary tube 1.

Like in the Fig. 1 can be seen, the rotary tube 1 may have a plurality of reinforcing elements 8. In this case, the number of reinforcing elements 8 may be in particular two to ten, preferably two to eight, particularly preferably three to six. It is inventively preferred that the reinforcing elements 8 are evenly spaced from each other or equidistant. Insofar as required by application or due to individual circumstances, an uneven spacing of the reinforcing elements 8 can equally be provided. For example, in the case of particularly stressed sections of the rotary tube 1, a larger number of reinforcing elements 8 can be fastened per unit length of the rotary tube 1.

The reinforcing element 8 may be made of metal, preferably steel. According to the invention, the reinforcing element 8 may consist of the same material as the rotary tube 1. The reinforcing element 8 or the rotary tube 1 can be particularly preferably made of high temperature resistant Steel exist. Due to the same material, the reinforcing element 8 and the rotary tube 1 at least substantially equal expansion coefficients, so that no additional material stresses due to a different expansion behavior of the reinforcing element 8 on the one hand and the rotary tube 1 on the other hand occur in the operating condition, ie at very high temperatures. In addition, this improves the compatibility of the welded joint.

Furthermore, it can be inventively provided that the reinforcing element 8 is designed as a cooling element or heat sink for optimized temperature control or to improve the cooling behavior of the rotary tube 1. According to this embodiment, the reinforcing element 8 may additionally be provided with cooling fins, which lead to a better heat dissipation behavior of the reinforcing element 8 and thus of the rotary tube 1 due to the increase in surface area.

As previously stated and as in the Fig. 1 . 2A, 2B 3A and 3C, mixing elements 3, for example turnable plates, for the circulation or thorough mixing of load 4 can be arranged in the interior 2 of the rotary tube 1. In this case, the mixing elements 3 can pass through the rotary tube 1 radially and in particular be welded externally to the rotary tube 1. For this purpose, the rotary tube 1 can have apertures 5 for receiving fastening sections 6 of the mixing elements 3, wherein the fastening sections 6 can be welded to the rotary tube 1 on the outside.

Like the detail enlargements a) to d) of Fig. 1 To illustrate, the reinforcing elements 8 may be arranged in different ways on the rotary tube 1.

So is the detail enlargements a) of Fig. 1 It can be seen that the reinforcing element 8 is annular and the rotary tube 1 completely encloses or comprises, wherein it is not in contact with the optionally provided mixing elements 3 and their attachment portions 6 is.

The detail enlargements b) to d) of Fig. 1 show embodiments according to the invention, according to which the reinforcing element 8 is externally connected to at least one attachment portion 6 and is in contact with the attachment portion 6. The connection of the reinforcing element 8 with the attachment portion 6 may preferably be effected by means of a welded connection, which may be a continuation of the welded connection 9.

The outside connection of the reinforcing element 8 with at least one attachment portion 6, in particular their welding, can be done due to the inventive arrangement of the mixing elements 3 and their attachment portions 6: The mounting portions 6 of the mixing elements 3 project outside of the rotary tube 1. In the context of the present invention is to be noted that the welding of the mounting portions 6 is formed with the rotary tube 1 to ensure proper operation of the rotary tube 1 gas-tight.

The detail enlargements b) to d) of Fig. 1 illustrate further the different arrangement possibilities of the reinforcing element 8 with respect to the mixing element 3 and its attachment portion 6:

This is how the section enlargement b) of Fig. 1 an arrangement according to which the attachment portion 6 extends on both sides to a certain extent perpendicular to the reinforcing element 8 and the reinforcing element 8 is thus arranged, for example at least substantially centrally to the extending in the direction of the rotational or longitudinal axis of the rotary tube 1 attachment portion 6 and the attachment portion. 6 so to speak "crosses". In order to ensure a flat abutment of the inner surface of the reinforcing element 8 on the outside of the rotary tube 1, according to this embodiment, the reinforcing element 8 may have at least one recess 10 for receiving the fastening section 6. The reinforcing element 8 according to the invention can be permanently connected to the fastening section 6 in the region of the recess 10, for example by means of welding.

According to detail enlargement c) of Fig. 1 is an embodiment of the invention can be seen, according to which the reinforcing element 8 in the region of the attachment portion 6 has an interruption or opening. In this case, the cross sections of the reinforcing element 8 are to a certain extent dull on the longitudinal side of the attachment portion 6. In this embodiment, too, a welding of the contact surfaces of reinforcing element 8 on the one hand and fastening section 6 on the other hand can be provided.

Finally, section enlargement d) of Fig. 1 a further inventive arrangement of the reinforcing element 8 on the rotary tube 1, after which the annular reinforcing element 8 rests with its side wall on the short side of the mounting portion 6 of a mixing element 3. It can be provided that the reinforcing element 8 is welded in the region of the contact point with the attachment portion 6. Also according to this embodiment may optionally be provided a recess of the reinforcing element 8 (not shown).

The optionally provided attachment of the reinforcing element 8 to the attachment sections 6 of the mixing elements 3 results in an additional stabilization of the rotary tube 1, since the respective elements - reinforcing element 8 on the one hand and attachment section 6 or mixing element 3 on the other hand - intermesh, so to speak, and thus to a certain extent additionally stabilize. As a result, in particular a stabilization of the mechanically heavily loaded mixing elements 3 is achieved, so that thereby an additional extension of the apparatus life is ensured.

As in Fig. 2A 4, the reinforcing element 8 can also be connected to a plurality of mixing elements 3 or their attachment sections 6 Fig. 2A the reinforcing element 8 is connected to the mixing elements 3 located at the top and bottom in the cross-sectional area, while the laterally arranged mixing elements 3 lie behind the reinforcing element 8 in the projection plane.

The present invention also covers such embodiments, according to which at least one particular annular reinforcing element 8 is connected to a plurality of mixing elements 3 and their attachment portions 6 so that the reinforcing element 8 is otherwise spaced from the rotary tube 1 and thus effectively fixed only to the mixing elements 3 is.

According to a particularly preferred embodiment according to the invention, the rotary tube 1 has a plurality, for example at least two, preferably three to six annular reinforcing elements 8, in particular of preferably high temperature resistant steel, wherein the reinforcing elements 8 peripherally about the rotary tube 1 and / or perpendicular to the axis of rotation of Rotary tube 1 extend. In this case, the reinforcing elements 8 of the longitudinal extent of the rotary tube 1 are arranged and preferably evenly spaced from each other. According to this particularly preferred embodiment, the reinforcing elements 8 are welded to the rotary tube 1 on the outside via a welded joint 9. Thus, the rotary tube 1 for mechanical stabilization in particular in pressure fluctuations by externally welded to the rotary tube 1 reinforcing elements 8, for example in the form of steel rings or steel strips reinforced. The reinforcing elements 8 in the form of steel rings or steel strips can, for example, "cross" the mixing elements 3 and the fastening sections 6, so to speak; At these so-called "crossing areas" the steel rings or steel bands may have recesses.

As regards the mixing elements 3 provided according to a preferred embodiment, these are located in the interior 2 of the rotary tube 1 and are advantageously distributed over the interior 2 of the rotary tube 1, so that an optimal circulation or mixing of the load 4 is ensured in the operating state. The mixing elements 3 can be permanently connected via their attachment portions 6 with the rotary tube 1 by external welding. The attachment portions 6 of the mixing elements 3 are so to speak pushed through the located in the wall of the rotary tube 1 openings 5 and protrude in particular on the outside a little out or forth, so that an external welding of the mounting portions 6 of the mixing elements 3 with the rotary tube 1 (ie, with the outer wall of the rotary tube 1) or the reinforcing element 8 is made possible.

The outside attachment of the weld 7 of the mixing elements 3 is associated with a number of advantages: Firstly, the welding site or weld prevents the weld 2 in the interior of the rotary tube 1 in the operating state prevailing aggressive conditions in the activated carbon production - corrosive acid Gases and high temperatures - is exposed. By attaching the outside welding, it is also possible to easily maintain this from the outside - even in the operating condition - to check or repair and repair if necessary. Finally, optimum welding materials can be used in this way, which ensure a good and safe permanent connection mixing elements 3 / rotary tube 1 or mixing elements 3 / reinforcing elements 8, but otherwise not permanently readily in operation 2 prevailing corrosive high temperature conditions inside the rotary tube 1 would withstand.

How out Fig. 1 and in particular the FIGS. 2A and 2B it can be seen, the external welding of the fastening portions 6 of the mixing elements 3 with the rotary tube 1 via a welded section 7. This welding section 7 advantageously has at least two welding layers or two welds 7a, 7b. The two welding layers or welds 7a, 7b are advantageously arranged or applied one above the other. This results in double welding layers or welds 7a, 7b. This has the advantage that different materials can be used for the different welding layers 7a, 7b. For example, in this way, welding materials of different temperature and corrosion resistance can be used or combined with each other, wherein the inner welding layer 7a should advantageously be corrosion and high temperature resistant, while a corrosion resistance in the outer welding layer 7b is not required to the same extent. By using a plurality of welding layers or weld seams 7a, 7b, a tight, in particular gas-tight and reliable welding of the connecting sections 6 of the mixing elements 3 with the rotary tube 1 is achieved. According to a particular embodiment of the present invention, one of both welding layers 7a, 7b austenitic, in particular fully austenitic, and the other formed austenitic ferritic-austenitic. Particularly preferably, the inner welding layer 7a is austenitic, in particular fully austenitic, and the outer welding layer 7b is formed in a ferritic-austenitic manner. According to a preferred embodiment, the welding takes place by build-up welding (eg by electrode welding). In general, the welding is carried out in such a way that the shit portion 7 is formed at least substantially gas-tight.

In general, the fixing portions 6 of the mixing elements 3 are formed so as to protrude on the outside. In other words, the fastening portions 6 protrude beyond the outer wall of the rotary tube 1 or out, which allows a good weldability and a good anchoring of the mounting portions 6.

The apertures 5 in the wall of the rotary tube 1, which serve to receive the mounting portions 6 of the mixing elements 3, are formed generally slit-like. By this particular slot-like openings 5 then the fastening portions 6 of the mixing elements 3 can be inserted, advantageously so that the mounting portions 6 project, ie protrude a little from the outer casing of the rotary tube, so that they can be better welded. This is in the FIGS. 2A and 2B seen.

As regards the attachment portions 6 of the mixing elements 3, various embodiments are possible to ensure a secure connection of the attachment portions 6 to the rotary tube 1: some of them are in the Figs. 3A to 3C shown. For example, there is the possibility that the attachment portions 6 of the mixing elements 3 extend over the entire investment or circumferential length of the mixing elements 3; In this case, the fastening portions 6 are completely inserted through the apertures 5 in the wall of the rotary kiln 1, and such an embodiment is in Fig. 3A shown. Alternatively, there is the possibility that the fixing portions 6 are shorter than the abutment or peripheral length of the mixing elements 3; Such embodiments are in the Figs. 3B and 3C shown. In the latter cases according to Figs. 3B and 3C For example, the mixing elements 3 can have a shoulder at the transition to the fastening cut 6, which serves in particular for contact with the inner side or inner wall of the rotary tube 1. It is also possible that the mixing elements 3 each have a plurality of engaging in different openings 5 mounting portions 6, as for example in Fig. 3C is shown.

As far as the mixing elements 3 are concerned, they may be formed, for example, like a blade or plate, in order to ensure a safe and intensive mixing and circulation of the load 4. According to one embodiment, the mixing elements extend at least substantially in the radial direction of the rotary tube 1, which ensures a particularly intensive mixing of the load 4. As mixing elements 3, for example, sheets, in particular angled sheets (angle plates), can be used, which mix the loading material 4 in the manner of a blade. This is known to the skilled person as such.

As far as the rotary tube 1, the mixing elements 3 and the reinforcing element 8 are concerned, they advantageously consist of high-temperature and corrosion-resistant material, in particular steel. For both the rotary tube 1 and the mixing elements 3 must withstand the extremely corrosive conditions of the carbonation phase and the high temperature conditions of the activation phase in the production of activated carbon. Examples of suitable high temperature and corrosion resistant steels from which the rotary tube 1 and / or the mixing elements 3 and / or the reinforcing element (s) 8 can be made are high alloyed steels, i. H. Steels with more than 5% alloying elements. Examples include high-alloy chromium and chromium / nickel steels, preferably with a chromium and / or nickel content of more than 10%, in particular more than 15%, particularly preferably more than 20%, based on the alloy. Preference is given to using ferritic or ferritic-austenitic steels with good corrosion and high-temperature behavior as the material for the production of the rotary tube 1 and / or the mixing elements 3 and / or the reinforcing element (s) 8.

Furthermore, the rotary tube 1 according to the invention advantageously has inlet and outlet devices for introducing and discharging as well as passing gases, for example for introducing inert gases for the carbonization phase in the activated carbon production and for introducing oxidizing gases for the activation phase in activated carbon production. This is not shown in the figures.

For improved maintenance of the interior 2 of the rotary tube 1, this may have in the wall of the rotary tube a so-called manhole, which is sealed to the rotary tube 1 and thus allows the entry of maintenance personnel in the interior 2 of the rotary tube 1 outside of operation. This is also not shown in the figures. In this way, maintenance of the interior 2 of the rotary tube 1 is ensured in a simple manner.

As described above, the rotary tube 1 according to the present invention is used particularly in rotary kilns for the production of activated carbon. The subject of the present invention - according to a second aspect of the present invention - is thus a rotary kiln having the previously described rotary tube 1 according to the present invention.

Another object of the present invention - according to a third aspect of the invention - is the use of a rotary tube 1 as described above or of this rotary tube 1 contained rotary kiln for the production of activated carbon. As described in the introductory part of the present invention, the production of the activated carbon is generally carried out by carbonization (synonymously also referred to as pyrolysis, carbonization or coking) and subsequent activation of carbonaceous starting materials, in particular organic polymers, such. Sulfonated organic polymers (eg, sulfonated divinylbenzene cross-linked polystyrenes) which are carbonated in the rotary kiln of the present invention and subsequently activated. The carbonization is generally carried out at temperatures of 100 ° C to 750 ° C, in particular 150 ° C to 650 ° C, preferably 200 ° C to 600 ° C, preferably under inert or at best slightly oxidizing atmosphere, as in the introductory part described. Carbonation may be preceded by a stage of precarbonization or pre-carbonization. In contrast, the activation is generally carried out at temperatures of 700 ° C to 1200 ° C, in particular 800 ° C to 1100 ° C, preferably 850 ° C to 1000 ° C. The carbonation is - as described in the introductory part - generally under controlled or selectively oxidizing Conditions, in particular under controlled oxidizing atmosphere performed. Suitable starting polymers of the abovementioned type are, in particular, ion exchange resins (for example cation exchange resins or acidic ion exchange resins, preferably with sulfonic acid groups, for example cation exchange resins based on sulfonated styrene / divinylbenzene copolymers) or their precursors (ie the unsulfonated ion exchange resins which before or during the carbonation process, it may be necessary to sulfonate it with a suitable sulfonating agent, such as, for example, sulfuric acid and / or oleum. For further details in this regard, reference may be made to the above statements in the introductory part.

The external attachment of the reinforcing elements or causes the mechanical stability or the dimensional stability of the rotary tube in the operating state, especially under extreme conditions (such as occur in the activated carbon production, for example), is considerably improved. In this way, a rotary tube is provided which can better resist mechanical deformation and is more resistant to strong pressure differences and pressure fluctuations and thus is dimensionally stable under operating conditions. The rotary tube according to the invention consequently has an improved service life with a reduced tendency for premature material fatigue. As a result, the process control and process control are facilitated.

The rotary kiln of the present invention enables the production of activated carbon from suitable carbonaceous raw materials by carbonization and subsequent activation in a single apparatus with relatively easy handling. Outer welding of the mixing elements provides an easy-to-maintain, low-repair-prone system capable of withstanding both the extremely corrosive conditions of the carbonation phase and the high temperature conditions of the activation phase; the external welding of the mixing elements allows the use of welding materials (= welding materials) which are optimally suited for welding, but which could not easily be used for internal welding, as they corrode the high temperature conditions inside the rotary kiln would not readily withstand during the operating state in the long term.

Further advantages, embodiments, modifications, variations and features of the present invention will be readily apparent to and understood by those skilled in the art upon reading the description, without thereby departing from the scope of the present invention.

Claims (13)

1. A rotary tube (1) for a rotary tube kiln for the production of activated carbon, wherein the rotary tube (1) is equipped on the exterior thereof with at least one reinforcing element (8) extending completely across the circumference of the rotary tube (1) for stabilizing the rotary tube (1) in the operating state,
   characterized in that
   the reinforcing element (8) consists of the same material as the rotary tube (1), wherein the reinforcing element (8) and the rotary tube (1) both consist of highly temperature-resistant steel,
   the reinforcing element (8), along with the rotary tube (1), is welded via a weld joint (9) extending along a contact line of the reinforcing element (8) together with the rotary tube (1) in a manner free of interruptions, and
   mixing elements (3) for the agitation and/or mixing of the charged goods (4) are arranged in the interior (2) of the rotary tube (1), wherein the rotary tube (1) comprises through holes (5) for receiving fastening sections (6) of the mixing elements (3), and the fastening sections (6) are welded onto the exterior of the rotary tube (1).
2. The rotary tube according to claim 1, characterized in that the reinforcing element (8) is embodied such that the reinforcing element (8) extends peripherally about the rotary tube (1), in particular perpendicular or at an angle to the rotary axis of the rotary tube (1).
3. The rotary tube according to claims 1 or 2, characterized in that the reinforcing element (8) is embodied in the shape of ribs, annularly, in particular as an annular flange, or in the shape of a screw line.
4. The rotary tube according to one of the previous claims, characterized in that the reinforcing element (8) extends axially along the rotary tube (1), in particular across the entire length thereof.
5. The rotary tube according to one of the previous claims, characterized in that the weld joint (9) comprises at least two welded layers (9a, 9b).
6. The rotary tube according to one of the previous claims, characterized in that the mixing elements (3) engage radially into the rotary tube (1), and are welded to the exterior of the rotary tube (1).
7. The rotary tube according to one of the previous claims, characterized in that the reinforcing elements (8) is connected, in particular welded, to the exterior of the at least one fastening section (6), in particular wherein the fastening sections (6) of the mixing elements (3) project on the exterior side.
8. The rotary tube according to one of the previous claims, characterized in that the reinforcing element (8) comprises at least one recess (10) for receiving a fastening section (6) of a mixing element (3).
9. The rotary tube according to one of the previous claims, characterized in that the exterior welding of the fastening sections (6) of the mixing elements (3) to the rotary tube (1) is carried out via a welding section (7).
10. The rotary tube according to one of the previous claims, characterized in that mixing elements (3) are embodied in the manner of vanes or plates.
11. A rotary tube kiln, in particular for the production of activated carbon, comprising a rotary tube (1) according to claims 1 to 10.
12. Use of a rotary tube according to claims 1 to 10 or of a rotary tube kiln according to claim 11 for the production of activated carbon, wherein the production of activated carbon is carried out by means of carbonation and subsequent activation of base materials containing carbon.
13. Use according to claim 12, characterized in that the carbonation is carried out at temperatures ranging from 100 to 750 °C, in particular 150 to 650 °C, preferably 200 to 600 °C, and/or that the activation is carried out at temperatures ranging from 700 to 1,200 °C, in particular 800 to 1,100 °C, preferably 850 to 1,000 °C.

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