WO1997013577A2

WO1997013577A2 - Flow reactor with capillary flow channels

Info

Publication number: WO1997013577A2
Application number: PCT/DE1996/001880
Authority: WO
Inventors: Hanno Wenske
Original assignee: Elwatec Elektrolyse- Und Wassertechnik Gmbh
Priority date: 1995-10-04
Filing date: 1996-09-27
Publication date: 1997-04-17
Also published as: DE19536971A1; WO1997013577A3

Abstract

A flow reactor is disclosed of the type described in the preamble to claim 1 and which may be used to carry out various chemical processes - such as, for example, the synthesis, the cleavage or the hydrogenation of substances. The reagents may be present in the liquid and/or gaseous phase.

Description

Flow reactor with capillary flow channels

description

The invention relates to a flow reactor according to the preamble of patent claim 1, which can be used for various chemical processes - such as the synthesis, cleavage or hydrogenation of substances. The reactants can be in the liquid and / or gaseous phase.

Catalytically operating flow reactors with capillary or capillary-like flow cross sections are known from the prior art, the fillings of which offer the reactants a large surface area. Depending on the specific application conditions, a wide variety of materials and geometrical configurations are used. The palette ranges from metal wool processed into nonwovens, to fine-grained, metallic and non-metallic (eg ceramic) bulk materials coated with catalyst material, to porous, sponge-like solids with a pore structure that is continuous for the material flow. All of the aforementioned reactor structures have the disadvantage that the capillary distances encountered within a packing differ very greatly and therefore cause locally different flow conditions, which means that the efficiency of the reactor can also be very different locally. In addition, the known fillings often have a very high hydraulic resistance, since the countless capillary flow cross sections of the reactor filling cannot be matched unidirectionally with the direction of the main flow. In addition to increased operating costs, high flow losses also result in higher plant-technical expenditures, for example for additional or more powerful pumps.

The invention is based on the object of developing a flow reactor with capillary flow channels which is distinguished by a high level of effectiveness and at the same time a low flow resistance. The capillary structure should be simple and inexpensive to manufacture and adaptable to the conditions of a wide variety of chemical or process engineering processes.

According to the invention the object is achieved by the characterizing features of patent claim 1. The dependent claims indicate preferred variants of the invention.

The capillary flow channels of the flow reactor according to the invention run essentially parallel to the main flow direction of the reactants and preferably have a relatively smooth surface. This ensures that the flow reactor, despite its large inner surface, has a comparatively low hydraulic see causing resistance. This enables higher flow velocities, which has a positive effect on the reaction kinetics and thus leads to an increased effectiveness of the flow reactor. In particular in the case of chemical processes which are carried out in the presence of a liquid phase, increased flow velocities advantageously influence the dynamics in the interface area (Helmholtz layer) of the liquid phase and wall of the flow channel. The so-called Nernst layer thickness is considerably reduced, which leads to a considerable acceleration of the course of the reaction, particularly in the case of catalytic processes.

Studies on flow reactors, built up from a large number of stacked film-like elements on the basis of a very smooth, glass-metallic, amorphous material, have shown that optimum reaction conditions are achieved in the capillary channels starting from a flow speed of 0.05 m / s become. The capillary channels designed as columns had an average width of 0.08 mm to 0.4 mm. It goes without saying that the flow velocity mentioned can only represent a guide value. The optimum flow rate in each case should be determined under real process conditions and using the reactor provided.

The flow reactor according to the invention with its essentially unidirectional directed flow channels can be designed in a variety of ways using a wide variety of materials. For example, the capillary columns can be formed from stacked film-like elements, the capillary columns from Profilings are fixed, which has at least every second of the film-like elements. Such profiles can be corrugations or embossments running transversely to the longitudinal axis of the film-like elements.

The materials can be chosen almost arbitrarily, i.e. a suitable material is used according to the specific application. Among other things, metallic materials come into question. If a catalytic effect is to be achieved and the production of the film-like elements from the catalyst material is uneconomical, the catalyst can also be applied subsequently or be part of an alloy which is the basis for the production of the film-like elements. The latter is particularly advantageous if the additional presence of an activator is required to carry out the chemical process.

Metals or metal alloys with amorphous or fine-grained structures are considered to be particularly activating. An inexpensive method for producing amorphous film-like tapes is to use the so-called melt-spinning process. This also allows alloys to be produced that would not be obtained in crystalline form. This applies both with regard to the possibilities of selecting the alloy partners and with regard to their proportionate composition. The thickness of the strips produced in this way is generally between 10 μm and 100 μm. By winding the film-like elements described, which are provided with profiles for capillary spacing, to form a spiral, a large number of capillary gaps running transversely to the spiral plane are created. The required length of the reactor is achieved by lining up a corresponding number of spiral bodies.

A further variant of the invention is based on band-like elements, the longitudinal axis of which runs essentially parallel to the main flow direction of the reactants. To maintain the capillary distance between adjacent elements, they only carry profiles over a small part of their width, which also extend along the longitudinal axis of the film-like elements. When using metallic elements, the profiles should preferably be designed as corrugations or bevels of the material and should be limited to at least one edge area of the element.

The advantage of the variant of the invention described last is that reactors up to several meters in length can be built with only one capillary-structured reactor insert. This means that for a certain reactor length only a few reactor inserts arranged one behind the other are necessary. This results in less pressure loss-causing transitions between the individual reactor inserts, so that the overall hydraulic resistance of the flow reactor is reduced. An advantageous area of application for the flow reactor is the removal of oxygen from the water of heating circuits and in particular from so-called boiler feed water, in order to counteract the corrosion of containers and pipelines. For this purpose, the surface of the flow reactor is coated with a suitable catalyst material, preferably from the platinum group, and the water to be treated is loaded with hydrogen in a stoichiometric ratio. The catalyst enables the dissolved oxygen to be converted into water with the supplied hydrogen, so that no reaction product to be discharged from the plant is formed.

The flow velocity through the capillary gaps in the capillary structure should not fall below a value of approximately 0.05 m / s.

The invention is explained in more detail below on the basis of exemplary embodiments and the figures shown. Show it:

FIG. 1 shows a schematic representation of a cross section through part of a flow reactor constructed from film-like elements;

FIG. 3 shows a perspective view of a section of a reactor packing consisting of several packing units;

Figure 4 from two film-like strips wound into a spiral packing unit; FIG. 5 reactor pack consisting of several spiral wound packing units;

FIG. 6a shows a perspective view of a section of a packaging unit with a corrugated film edge and an adjacent capillary gap;

FIG. 6b shows a perspective view of a section of a packaging unit with a bounded film edge and an adjacent capillary gap;

FIG. 7 cross section through a packing unit with a central elastic range and film edges profiled on both sides;

FIG. 8 broken pack unit with profiled film-like elements, as indicated in FIG. 7;

A first variant for the design of the flow reactor according to the invention consists in the parallel arrangement of a plurality of film-like elements la, lb, with straight elements la and elements lb profiled by corrugation alternating. Figure 1 shows a greatly enlarged section of the arrangement described. Capillary flow channels 10a are formed between the elements 1a, 1b, the cross-section of which depends on the height of the corrugations. The cross-section of the capillaries can be compressed by compressing the film-like elements which are stacked together Flow channels 10a practically reduced as desired and thus optimally adapted to the prevailing conditions.

Insofar as a metallic capillary structure is provided, in many cases this can be produced particularly cheaply by means of ribbon-shaped film elements 1a, 1b which were produced by the so-called melt-spinning process. The desired alloy, optionally with the addition of catalyst and activator material, is transferred in the liquid state from a mold to a rotating, cooled drum, where the melt is quenched at a rate of approx. 1 million ° K per second and the amorphous Condition of the melt is frozen. The material has a comparatively smooth surface. It can currently be manufactured with a thickness of approx. 10 μm to 120 μm and a width of up to approx. 0.5 m.

FIG. 3 schematically shows a reactor packing consisting of four packing units 14, the capillary structure of which was constructed from the above-described film-like elements la, lb or lc or similar elements. Their profiles (corrugations or spacers) guaranteeing the capillary distance 10 between adjacent elements 1 extend parallel to the direction of flow of the reactants and thus transversely to the longitudinal extent of the band-shaped elements 1. The stacked units 14 are stacked the neighboring one rotated by 90 degrees, so that the individual elements 1 intersect. FIG. 4 shows a further possibility for producing a capillary structure on the basis of film-like elements 1a, 1b. Accordingly, the straight, non-profiled band-shaped element 1a and the corrugated element 1b are wound together to form a spiral packing unit 14a, which due to its circular outer contour is particularly suitable for use in a cylindrical reactor. FIG. 5 shows a reactor packing constructed from a plurality of wound packing units 14a. Here, too, the capillary flow channels 10a can be dimensioned by more or less tight winding and can thus be adapted to the prevailing conditions.

FIG. 8 shows a section of a capillary-structured packing unit 14b, the band-shaped elements of which extend along the flow direction 17. For this reason, the profiles 15, which are designed in the form of corrugations, also extend along the flow direction 17. The elements corrugated in their edge region include intermediate capillary gaps 10b. FIG. 7 shows a small part of the packing unit 14b in cross section.

FIGS. 6a and 6b show two variants of the packaging unit 10b described last and shown in FIG. 8 in a greatly enlarged perspective illustration. According to FIG. 6a, the packing unit consists of individual elements 1d profiled on one side by corrugations 15, the corrugations 15 of the adjacent elements 1d being arranged alternately on the left or right. The capillary columns 10b also extend along the flow direction 17 of the reactants. The one shown below The pack cut-out consists of alternately arranged profiled elements lee and non-profiled elements le, the profiled elements lee carrying material barriers 16 in both edge regions. A device with profiling rollers is particularly suitable for generating the profiles 15, 16.

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Reference list

I film-like element la film-like element (straight) lb film-like element (corrugated) lc film-like element with spacers ld film-like element (edge area profiled on one side, corrugated) le film-like element (not profiled) lee film-like element (edge area profiled on both sides, set) lf film-like element (Edge area profiled on both sides, corrugated)

10 capillary gap, flow channel

10a capillary gap, flow channel

10b capillary gap, flow channel

II spacer

12 Width of the film-like element

13 thickness of the film-like element

14 packing unit 14a packing unit

15 Corrugation of the edge area

16 Edge margin

17 flow direction

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Claims

claims

1. flow reactor with capillary flow channels running essentially parallel and in the direction of the main flow for carrying out chemical processes in the liquid and / or gaseous phase, using stacked thin, film-like elements which delimit the walls of the flow channels,

characterized,

that the film-like elements are continuous strips that can be produced with a maximum thickness of 120 μm and a width of 2 mm to 30 mm, that the flow channels are formed as capillary gaps between the adjacent strips and that the capillary distance between the adjacent strips is determined by Profiling (11, 15, 16) of at least every second film-like band (1, lb, lc, ld, lee, lf) is secured, the profiling (11, 15, 16) by plastic deformation of at least a portion of the band (1 , lb, lc, ld, lee, lf) are generated.

2. Flow reactor according to claim 1, characterized in that the profiles are formed as material corrugations if the direction of the main flow is transverse to the longitudinal axis of the film-like band. 13577 PC17DE96 / 01880

13

Flow reactor according to claim 1 or 2, characterized in that a film-like band or a plurality of stacked film-like bands (la, lb) are wound simultaneously into a spiral (14a), so that the spiral (14a) has a plurality transverse to the spiral plane running capillary gaps (10a) forms.

Flow reactor according to claim 1, characterized in that the profiles (15, 16) of the foil-like strips (ld, lee, lf) are only a small part of the width and along the longitudinal axis of the strips (ld, lee, lf ) extend when the direction of the main flow runs along the longitudinal axis of the film-like band, so that capillary gaps (10b) are formed, which extend continuously over the entire length of the bands (ld, lee, lf).

Flow reactor according to claim 4, characterized in that the profiles are limited to at least one edge region of the film-like elements (ID, LEE, IF) and that the profiles are preferably designed as corrugations (15) or inclinations (16) of the material .

Flow reactor according to at least one of the preceding claims, characterized in that the film-like elements (1, la, lb) consist of an amorphous (so-called glass-metallic) material produced by the melt-spinning process. 7. Flow reactor according to claim 6, characterized gekennzeich¬ net that the amorphous film-like elements (1, la, lb) are doped with a catalyst and / or activator.

8. Flow reactor according to at least one of the preceding claims, characterized in that it comprises a plurality of packing units (14, 14a) arranged along the path of the main flow (17) with essentially unidirectionally oriented capillary gaps (10, 10a). is formed.

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