This invention relates to a reactor for the conversion of a gaseous or liquid reaction medium with at least two reaction spaces at least partly filled with a catalyst, which are formed in that in the reactor at least three heat transport spaces arranged substantially parallel to each other are provided, which at least partly separate the individual reaction spaces from each other, wherein the heat transport spaces are formed by at least one thermoplate each and wherein each thermoplate consists of two plates which are welded together at their edges and over whose surface a plurality of spot welds, which likewise connect the plates, are distributed. This invention also relates to a process for the reaction control in such reactor. A number of typical heterogeneously catalyzed gas phase reactions are carried out in so-called fixed-bed reactors. In the process, a bed (fixed bed) of catalyst particles or carriers coated with catalyst each is traversed by the reaction medium. Subsequently, the reaction medium flows through a heat exchanger, in order to at least partly dissipate the reaction heat obtained, before it enters into the next catalyst bed. Alternatively, the temperature decrease also can be realized by introducing a material stream for quenching. In general, typical reactors have 4 to 6 fixed beds which are traversed one after the other.

Using the example of a conversion of methanol to propylene (MTP process) the configuration of such fixed-bed reactors will be explained in more detail. Figure 1 shows a reactor as it is usually employed for the conversion of methanol to propylene. Via conduits 1 3 and 1 3i methanol is supplied to the reactor 1 0 over head. From there, it first arrives at the fixed bed 1 1 in direction of gravity, in which fixed bed at least parts of the methanol are converted to propylene. As the reaction proceeds exothermally, reaction heat is released, which is dissipated in the heat exchanger ^' \ 2 ^< _\ . Alternatively, the temperature decrease also can be realized by introducing a material stream for quenching. The desired temperature before entry into the succeeding fixed bed 1 1 ₂ , however, also can be achieved by adding a correspondingly conditioned material stream (e.g. methanol) as quenching stream. Subsequently, the mixture of oxygenate, preferably methanol, propylene and other reaction products, enters into the fixed bed 1 1 ₂ . Via a conduit 13 ₂ , fresh oxygenate here usually is supplied once again above the actual fixed bed, whereby the conversion in each fixed bed and thus also the heat quantity obtained can be controlled in addition. Subsequently, the educt-product mixture is guided over the heat exchanger 12 ₂ . The same is repeated in the fixed beds 1 13, 1 14, 1 5 and 1 1 ₆ as well as the corresponding heat exchangers 12 ₃ , 1 2 ₄ , 12 ₅ and 12 ₆ as well as the feed conduits 13 ₃ , 13 ₄ , 13 ₅ and 1 3 ₆ . Finally, the product mixture is withdrawn via conduit 14. In a typical MTP plant three of these reactors each are provided, two of which each are operated in parallel and the third one is in stand-by or the catalyst just is being regenerated. A typical design of such plant and process is to be found in DE 10 027 159 or also in US 2009/01 24841 . After completion of the catalyst regeneration, the reactor is again put into operation with the regenerated catalyst, while that reactor which contains the catalyst with the longest service life now is supplied to the regeneration. Thus, in a typical production line always 2 reactors are in the operating mode, which carry out the reaction, but which are filled with catalysts with different ageing conditions. The reaction concept of today requires a large reactor volume of about 2000 m ³ (for a plant capacity of about 450 kta of propylene), which results from the fact that beside the adiabatic catalyst beds the cooling zones mentioned already must be provided in the form of heat exchangers or quenching sections. In addition, a corresponding space must be provided for charging and draining the catalyst. In general, six fixed beds are arranged one above the other, which each have a height of 20 to 60 cm. In each reactor about 150 Mt of catalyst are distributed over these six catalyst beds, with the total quantity of catalyst rising with the beds. This means that in the first bed less catalyst is to be found, so that here the reaction deliberately cannot proceed completely, but is limited by the catalyst quantity. This should prevent a runaway of the reaction as a result of too much local production of heat by exothermal reactions. By the fact that the last, sixth bed, contains the largest quantity of catalyst, it can be ensured that the methanol is converted completely or approximately completely.

Usually, approximately 1 00 compartments are present in each fixed bed, which individually are filled with catalyst. This process turns out to be relatively expensive as compared to the concept of the invention (only 1 bed). When the fixed bed is traversed by the catalyst, care should be taken that later on all compartments are approached uniformly, in order to avoid local catalyst damages. In addition, it must also be avoided that the catalyst gets in contact with liquid, as this can lead to a permanent damage of the catalyst. To adjust the temperature in each fixed bed, reaction medium partly converted already also is mixed with fresh reaction medium.

Furthermore, care must be taken in the reactor that a pressure loss as low as possible occurs via the fixed bed, so as to ensure the selectivity towards the target products, the short-chain olefins, particularly propylene. As explained above, the reactor concept of today for the usual propylene capacity of more than 450,000 t per year requires a comparatively large reactor volume and a corresponding reactor diameter, in order to minimize the pressure loss. Therefore, the reactor cannot easily be designed still larger and construction and transport also are limited.

In summary, a potential for improvement very well exists in the described plant set-up, in particular with regard to the very large reactor volumes and diameters, the challenging distribution of the reaction medium and the relatively expensive catalyst handling.

It therefore is the object of the present invention to provide a reactor with smaller dimensions, in which exothermal reactions, in particular the MTP reaction can be carried out, wherein a uniform temperature profile with low pressure loss is the objective of the design. In addition the handling, in particular the filling with new catalyst should be facilitated. This object is solved by a reactor with the features of claim 1 .

Such reactor for the conversion of a gaseous or liquid reaction medium comprises at least two reaction spaces at least partly filled with a catalyst. These reaction spaces are formed in that in the reactor at least three heat transport spaces arranged substantially parallel to each other are arranged. Substantially in the sense of the invention means that the course of the heat transport spaces maximally deviates from each other by +/- 20°, preferably by 10°, particularly preferably by 5°, quite particularly preferably by 2°. These individual, parallel heat transport spaces at least partly separate the individual reaction spaces from each other.

The heat transport spaces each are formed by at least one thermoplate. A thermoplate in the sense of the invention consists of two plates which are connected, preferably welded together, at their edges and over whose surface a plurality of additional connections, preferably spot welds, are distributed, which likewise connect the plates with each other. Such plates can be produced by robots or machines in an automated way and thus at very low prices. After welding, the plates are expanded by hydraulic forming, in general by pressing in a liquid under high pressure, whereby cushion-like channels are obtained between the plates. Via the heat transport spaces thermal energy can both be supplied to the reaction and removed from the reaction, wherein in the following exothermal reactions will be discussed primarily, in which accordingly a removal of thermal energy is required.

It now is the subject-matter of the invention that in operation the horizontal extension of the reactor in at least one axis is greater than its vertical extension. This means that the flux of the reaction medium extends orthogonally to the horizontal axis of the reactor. The thermoplates can be oriented in parallel one beside the other on the horizontal axis or orthogonally to the horizontal axis in the reactor.

Compared with the previous reactors, the arrangement in the reactor according to the invention is changed. The inlets and outlets for the reaction medium are provided such that the reactor is vertically traversed by the reaction medium. Preferably, the through-flow is effected such that the flow direction is in line with the force of gravity. This has the advantage that during the through-flow no structural changes can occur in the fixed bed of the catalyst. The inventive design of a reactor which is formed less in the height than in the width offers a plurality of advantages. On the one hand, various fixed beds with interposed heat exchangers can be omitted in principle, but the thermoplates rather are located within an individual fixed bed. On the other hand, there now are obtained dimensions which involve a distinctly lower pressure loss, since the flow of the reaction medium already must split up above the individual reaction spaces, in order to pass through the individual reaction spaces. The reaction medium then in each case only flows through one fixed catalyst bed with the vertical height of the reactor, instead of through a plurality of fixed beds like in the previously customary embodiment. The term reactor container in the sense of the invention means a container in the interior of the reactor, which at least comprises the thermoplates and their interspaces and in the term is at least partly, preferably completely filled with catalyst. The significantly reduced path length of the reaction medium also leads to distinctly lower pressure losses. Due to the reduced path length of the reaction medium, the conditions in general along the path length covered by the reaction medium also are much more uniform than in a reactor design in which the reactor is traversed along a distinctly longer vertical path. This leads to the fact that in the reactor according to the invention the reaction control can proceed distinctly closer to the ideal isothermal reaction conditions and thus less by-products and more of the desired product, for example propylene, can be formed.

Furthermore, the exchange of the catalyst is simplified distinctly, as here less beds, preferably one bed instead of the 6 fixed beds customary for example in the MTP process, must be exchanged. Furthermore, the reactor has a distinctly smaller diameter, whereby the transport and the construction is greatly simplified.

Finally, such reactor has the advantage that it allows a very simple design for larger and smaller capacities, as from the critical quantity of at least 10 thermoplates, which form 10 heat transport spaces, it must be assumed that the reaction conditions in each reaction space are the same and thus the number of the reaction spaces can be calculated directly by simple multiplication based on the quantity of desired product. At the same time, it also is possible at long last to fabricate reactors which convert a smaller quantity, so that the reactor in particular also seems more expedient for small plants than the previous reactors which have required certain minimum dimensions. In particular for the approach of generating methanol from renewable raw materials, which necessarily will lead to a decentralization of the further processing of methanol, this concept is very promising. In principle, it is possible with this concept to realize capacities of less than 1 00 kt of propylene per year.

In addition, with only one fixed bed the so-called steaming, i.e. a pretreatment of the catalyst with steam, is greatly simplified, as only one fixed bed must be treated yet and thus a better control of the temperature profile during the steaming operation is possible.

The reactor dimensions preferably are designed such that a person can work therein without any problems and all parts are easy to reach. This in particular simplifies maintenance work. However, smaller reactor dimensions, in particular for small production capacities, also are possible.

Furthermore, it is preferred when the reaction spaces extend vertically along the extension of the heat transport spaces. In practice this means that in the lower part of the reactor, i.e. the region which in operation is closest to the surface of the earth, exclusively fixed catalyst bed is to be found, but no thermoplates, so that the reaction here proceeds adiabatically. As this is the region in which the reaction medium already is converted for a large part, because it already has flown vertically through the fixed catalyst bed along the longest path length, a completion of the conversion can be achieved at this point due to the adiabatic reaction conditions.

It also turned out to be favorable when the additional connections, preferably spot welds of the thermoplate, lie on straight lines, wherein a straight line is defined by the fact that the respectively adjacent welding spots lie on a straight line. Preferably, the distance of the individual points, which lie on a straight line, to each other always is the same distance d3, and the straight lines always have the same distance d5 to each other, i.e. extend in parallel. It is particularly preferred when the points on the individual straight lines are arranged offset to each other, so that straight lines only are to be found within one dimension. This results in a system which equally ensures sufficient channels for an optimum exchange of heat and thus a uniform temperature over the entire thermoplate. In a particularly preferred embodiment the thermoplates include the cushion-like channels mentioned already between the additional connections, preferably spot welds, in which channels the maximum distance of the two plates to each other is the distance d2. At the same time, the distance between two adjacent thermoplates is referred to as d1 . According to the invention, the distance d1 between the two adjacent thermo-surfaces and hence this reaction space always is larger than d2, namely the maximum expansion of the thermoplate between two additional connections, preferably spot welds. At the same time the distance d1 always is smaller than a hundred times the distance d2. It therefore is an aspect of the invention that the advantageous isothermal reaction control mentioned already can be ensured in particular when these two geometrical parameters are adapted correspondingly.

It is particularly favorable when the distance and thus the width of a reaction space d1 lies between 1 .5 times d2 and 10 times d2. Quite particularly for the production of propylene from methanol this results in an optimized reaction control, in which hot spots in the fixed catalyst bed can be excluded just like spots which are so cold that no reaction at all or even the condensation of methanol occurs.

One aspect of the invention is the integration of an apparatus for the removal of the catalyst. The same for example can be designed such that the support surface of the catalyst can be opened by a folding mechanism, so that the catalyst falls down. Another, particularly space-saving design provides to divide the support surface of the catalyst into at least two parts and to support the same on rails such that one part of the support surface each can be pushed under the respective other part and the catalyst thus falls down by gravity.

Furthermore, it is a particularity of the invention that the thermoplates are designed such that they are suitable for guiding a salt melt. Beside an optimized guidance with regard to the temperature profile, the channels in the thermoplates are configured such that in the case of a shut-down or decommissioning a quasi complete drainage of the cavities in the thermoplates by means of gravity is ensured. After cooling of the apparatus no solidified salt thus is left in the thermoplate and reduces the risk of a damage of the thermoplate. Recommissioning also is facilitated thereby correspondingly. The utilization of a salt melt has the advantage that the wall thickness of the thermoplates can be distinctly smaller than with the customary use of high- pressure steam as heat transport medium, as the pressure load correspondingly is lower. The heat transfer thereby is strongly improved again. At low pressures within the thermoplates, such as in use of salt melts, there will preferably be chosen wall thicknesses between 0.5 and 1 .5 mm per plate (thermoplate consists of 2 plates) - for reasons of construction some manufacturers prefer to not go under 1 mm. In systems with high pressures there will rather be used wall thicknesses between 1 .5 and 3 mm - greater than 3 mm hardly is possible, as the plate not longer can be deformed correspondingly, but with 3 mm design pressures of distinctly above 100 bar already can be realized here. Furthermore, it also is possible to utilize high-pressure steam as heat transport medium, as it is usually done when using thermoplates. Such high-pressure steam has a pressure of up to 1 00 bar and therefore has a corresponding thermal capacity. Larger plant complexes generally are configured with steam systems with different pressures (high-, medium- and low-pressure steam), which are suitable for conducting energy between the individual plant components, and wherein electricity in part is gained from generated steam. The incorporation of the reactor type according to the invention in such high- pressure steam system therefore is recommendable in particular in a plant complex.

Another aspect of the invention provides that the reaction spaces filled with a catalyst bed and the associated heat transport spaces are dimensioned such that per cubic meter of catalyst the reactor includes at least one thermoplate and/or per cubic meter of catalyst bed has at least 10 m ² of cooling surface, wherein the cooling surface directly constitutes a surface of one of the two plates of the thermoplate. This results in a surprisingly simple correlation with respect to the total quantity of the thermoplates used. Another aspect of the invention provides that in individual thermoplates passage openings are provided from one reaction space to another, for example by holes within the thermoplates, wherein the two plates are tightly connected with each other by a circular weld at these holes. Through these additional openings the reaction medium can mix via the reaction spaces, whereby the homogeneity of the product can thereby be increased further.

Furthermore, the invention comprises an apparatus in which the reactor provides a gas distribution device by which the reaction medium is uniformly distributed on all reaction spaces. Such gas distribution device of such distributor either can be a distribution chamber from which a plurality of openings (the same can e.g. also be designed as slots which e.g. extend along or transversely to the horizontal reactor axis) or nozzles makes the reaction medium flow into the reactor with its reaction spaces, whereby a very uniform distribution over all reaction spaces can be achieved. It likewise is also possible to introduce the reaction medium without a distribution chamber directly via nozzles above the reaction spaces, from where it is distributed over the various reaction spaces. In principle it is possible to operate with larger and smaller nozzle quantities and corresponding connecting valves and tubes, or however to design the individual nozzles and the associated equipment larger. A large number of nozzles has the advantage that the distribution of the reaction medium can be effected in an optimized way in the sense of a distribution as uniform as possible and a higher flexibility also is possible with regard to different approach flow rates in different reaction spaces.

The catalyst in part can also be placed within the reaction spaces through a corresponding grating or another device. This has the advantage that a carrier structure can be incorporated, which together with the catalyst can again be removed from the reaction spaces.

It also is advantageous to apply a net and/or inert material above the catalyst, in order to place the catalyst in that region which faces the inflow of the reaction medium, in particular at a point where no heat transport medium is provided yet, or where such inflow just starts, but the heat dissipation is reduced. The catalyst thereby can be protected in addition. Furthermore, it also is possible to also introduce inert material together with a catalyst bed, so that the catalyst density in the bed is reduced and thus the local reaction rate also is lowered. What also is conceivable is a non- homogeneous catalyst bed by which the local reaction rate can be influenced in addition.

The subject-matter of the invention also is a process for converting a gaseous or liquid reaction medium in a reactor with the features of claim 1 1 . Such reactor comprises at least two reaction spaces at least partly filled with a catalyst, which are traversed by the reaction medium. The reaction spaces are formed by at least three heat transport spaces arranged substantially parallel to each other, wherein a heat transport medium flows through the heat transport spaces.

The heat transport spaces each consist of at least one thermoplate, wherein each thermoplate in turn consists of two plates which are welded together at their edges and over whose surface a plurality of spot welds, which likewise connect the plates, are distributed.

It is the subject-matter of the invention that the reaction medium flows through the reactor vertically, preferably in direction of the force of gravity, and that the horizontal extension of the reactor in at least one axis is greater than its vertical extension. This offers the advantage that loading and unloading with the catalyst is simplified distinctly. Furthermore, the reactor itself also is much easier to handle due to an altogether narrower diameter. Using the example of a conversion of methanol to propylene a reactor with a capacity of 100-250 kt per year or also less, which is reduced in size with respect to current plant capacities, also is conceivable.

It is decisive that thus a very homogeneous flow approaches the catalyst bed, an isothermal reaction control is achieved, and at the same time the pressure loss is lower than in the case of a conventional reaction control.

It is one aspect of the invention that the heat transport medium is guided in cocurrent flow to the reaction medium. This has the advantage that the largest temperature difference between reaction medium and heat transport medium occurs in the region of the entry of the reaction medium into the reaction spaces, where locally the highest degrees of conversion and thus also the largest development of heat exists in the case of an exothermal reaction. It is, however, also possible to supply the heat transport medium in counterflow or even in cross flow (depending on the arrangement of the thermoplates which can be oriented both vertically and horizontally to the flow direction of the reaction medium), as in this way a more homogeneous temperature profile can be generated in general.

Furthermore, there can be used any form of heat transport medium in liquid or gaseous form. Due to its mostly higher thermal capacity, a liquid heat transport medium generally is preferred, quite preferably a medium which evaporates within the thermoplates, where due to the additionally required evaporation enthalpy an even more isothermal reaction control becomes possible.

Preferably, individual regions of the reaction spaces are operated adiabatically, wherein the conversion can be increased further. Finally, it is an embodiment of the invention that the process which is carried out in the reactor according to the invention is the at least partial conversion of methanol to propylene, which represents a typical reaction in the fixed bed, which with the previous reactor arrangement requires a very large reactor with the related disadvantages.

Further features, advantages and possible applications of the invention can be taken from the following description of the drawings and the examples. All features described and/or illustrated form the subject-matter of the invention per se or in any combination, independent of their inclusion in the claims or their back-references. In the drawings:

Figure 1 shows the construction of a conventional multistage fixed-bed reactor,

Figure 2 shows the construction of a reactor according to the invention, and

Figures 3a and 3b show the construction of a thermoplate used.

Figure 1 already has been discussed with respect to the prior art.

Figure 2 now shows a reactor 20 according to the invention. Via a feed conduit 22 educt, such as methanol, is introduced into a distributor chamber 23. From this distributor chamber 23 a plurality of openings, for example slots, branch off, which lead into the reactor 20. The distributor chamber 23 can be placed directly on the reactor 20 or even be part of the reactor 20 and for example be formed by a bulge. The distance between the openings and the actual reaction region however also is to be chosen such that a uniform flow approaches the reaction region. At the same time it also is possible in a non-illustrated way to introduce the reaction medium into the reactor 20 via nozzles. The nozzles then are to be arranged such that a uniform through-flow is ensured. The reaction spaces 25i to 25 ₆ are defined by heat transport spaces 24-i to 24 ₇ which are formed of at least one thermoplate. The reaction spaces 25^ to 25 ₆ are at least partly filled with catalyst, as indicated, on which the reaction medium, such as for example methanol, can be converted.

The product stream obtained is withdrawn via conduit 26.

The distance between two adjacent heat transport spaces 24 _n to 24 _n+ each defines a reaction space 25 _m with the width d1 . The arrangement is made such that the reaction medium first vertically flows through the reaction spaces 25^ to 25 ₆ from top to bottom and in the lower adiabatic region 21 the reaction spaces are not separated from each other by individual heat transport spaces 24 to 24 ₇ . In this region 21 the reaction proceeds adiabatically, as there is no heat dissipation or heat supply. In the region of the heat transport spaces 24 to 24 ₇ an approximately isothermal reaction control can be assumed. The heat exchanger plates 24i to 24 ₇ also each have at least one non-illustrated inlet and outlet. It also is possible in a non-illustrated way to already provide a catalyst above the heat transport spaces and thus expand the reaction spaces. The catalyst rests on at least one holding device 27, such as for example a suitable grating. This holding device 27 can be shifted or released via a removal device 28, so that the catalyst falls down and can easily be removed at the bottom of the reactor 20. Figure 3a shows an x-y-view on a thermoplate 30 over the surface of a plate which forms one side of the thermoplate. The points 31 1 to 31 ₉ represent the so-called welding points with which the plate is connected with the non- illustrated plate on the opposite side by an additional spot weld. The points 31 1 to 31 3, 31 4 to 31 6 and 31 ₇ to 31 ₉ each lie on a straight line, wherein the points of each second straight line in alternation again lie on a straight line in the respective other dimension. The straight lines extend parallel to each other and have the distance d5. In that the thermoplate is welded together not only at the edges of two superimposed plates, but additional welding spots 31 1 to 319 are located thereon, the sectional representation as shown in Figure 3b is obtained in the x- z-view through a thermoplate. Between the individual spot welds 31 1 to 31 ₉ channels 32-i and 32 ₂ are formed, which in general are produced by pressure forming, particularly preferably by internal high-pressure forming. The diameter d2 of such channel 32i or 32 ₂ describes the distance between the two plates 30a and 30b at the maximum channel formation, while the diameter d4 designates the thickness of the welding spot 31 1 to 31 ₉ . The distance between two welding spots 31 1 to 319, which also exactly corresponds to the distance of two welding spots 31 1 to 319 on a straight line, corresponds to d3. Preferably, the following applies: d3 > d2 > d4.

Exemplary Embodiments

Example 1

Example 1 shows the differences in a reactor design in comparison with a reactor according to the prior art, as it is shown in Figure 1 , and the reactor according to the invention, which is designed ring-shaped in the horizontal. The data for the reactor according to the prior art each are stated as 100 %, whereas the reactor according to the invention is stated in relation thereto.

Table 1 : Comparison of the geometrical dimensions of a reactor according to the prior art and the reactor according to the invention.

The cross-sectional area in the horizontal can be filled out round, but of course also in any other shape. It is decisive that the shape of the reactor provides for a good distribution of the reaction medium and an easy handling of the catalyst. It becomes clear that the dimensions of the reactor according to the invention are reduced distinctly, as due to the local dissipation of heat the very large heat exchangers ultimately can be omitted. The ratio of catalyst to reactor volume is increased almost threefold. The space-time yield in the reactor according to the invention hence is improved drastically. Example 2

With reference to a simulation carried out with Matlab®, Example 2 shows that the propylene selectivity in the reactor according to the invention can be increased by at least 2 % by an improved reaction control, closer to an isothermal operation. This is in correlation with the fact that a far smaller temperature difference exists over the entire flow path of the reaction medium. The data for the reactor according to the prior art each are stated as 1 00 %, whereas the reactor according to the invention is stated in relation thereto.

Table 2: Comparison of the geometrical dimensions of a reactor according to the prior art and the reactor according to the invention.

Parameters Prior art Reactor according to the invention

Catalyst weight (t) 150 150

Total catalyst bed height (m) 100% 100%

Total increase in temperature 100% about 15%

(K)

Heat dissipation (MW) 100% 100%

Pressure loss over the reactor 100% about 70%

Pressure of the reaction mixture 100% 100%

at the outlet (bar)

Temperature of the reaction 480 °C 480 °C

mixture at the outlet (°C)

Propylene selectivity (mol C-%) 65 > 67 Table 3 shows the yield of propylene in dependence on a temperature deviation from the ideal reaction temperature

Usual reactor systems show a deviation of about 1 5 K and thus a propylene yield of 65 mol C-%. The novel reactor system will be in the range 1 0 to 0 K, preferably in the range 2.5 to 0 K for the average temperature deviation from the optimum reaction temperature. The propylene yield hence is increased distinctly.

List of Reference Numerals:

10 reactor according to the prior art

1 1 1 - 1 1 6 fixed bed

12-1 - 12 ₆ heat exchanger

13, 1 3-1 - 136 methanol feed conduit

14 product discharge conduit

20 reactor according to the invention 21 adiabatic region

22 feed conduit

23 distribution chamber

24-i - 24 ₇ heat transport space

24D passage opening

25-I - 25 ₆ reaction space

26 discharge conduit

27 holding device

28 removal device 30 thermoplate

30a, 30b plate

31 1 - 319 welding spot

32-1 , 32 ₂ heat transport channel