EP1384502B1 - Mixer, heat exchanger - Google Patents

Abstract

The combined static mixer and heat exchanger has a housing (6) with heat exchange pipes (1) with projecting blades (2a,2b) at their circumference, which act as static mixers in at least two parallel levels. The blades are offset from each other by an angle (alpha) of 45-135 degrees and especially 70-110 degrees around the pipe axes. The blades are pitched an angle (beta) to the material flow direction of +/-10 degrees to +/-80 degrees.

Description

The invention relates to a combination of static mixer and heat exchanger for the processing of thermally sensitive viscous media, consisting of several parallel side by side, one above the other or staggered tubes which are transversely at an angle, preferably of 90 ° to the product flow direction in a housing and be streamed. The tubes have on the outer diameter raised radially arranged webs or curved, which are arranged axially offset from the tube axis and are offset from each other on the tube axis. The raised contours are arranged so that a good mixing effect occurs in particular for viscous and highly viscous substances and mixtures and at the same time a fast product-gentle temperature control is made possible by the significantly enlarged outer tube surface.

The fast, even and gentle tempering of viscous and highly viscous products, for example polymer melts, is insufficiently achieved with the known static mixer systems described below. As direct heating surface for such tasks, only the outer tempered housing or pipe wall is available. For temperature control of a product, this is repeatedly passed through the known static mixer from the housing or tube center to tempered housing wall, so that with increasing length of the heating the desired product temperature is reached. Such tempering tasks require due to the low thermal conductivity of most organic substances long-tempered mixing lines, which lead to a high residence time and high pressure drop and thus viscous substances (> 1 mPa.s) at laminar flow velocity, especially those with temperature-sensitive character damage. An additional disadvantage of the long mixing lines are the high design-related investment costs of such systems. Disadvantages, such as low mechanical stability and high Pressure losses of known static mixers lead to large flow cross sections, which in turn make temperature control more difficult.

A slight improvement in Temperieraufgaben is achieved when known static mixers are pressed or rolled in pipes or in housing. As a result, a limited metallic contact between the heated inner housing wall and the small outer cross-sectional areas of the metallic static mixer is formed. However, the drawn or rolled Static mixer can only form an insufficient contact surface with the tempered housing wall. Experience has shown that the contact surfaces are not completely formed so that gaps always form towards the inner housing wall. Due to the high heat conduction properties of the metallic mixing webs, heat is conducted radially through this narrow gap radially into the flow region of the static mixer. This method allows only for very small housing or pipe diameters little improvement, since the heat conduction to the center of the static mixer or the housing is limited by the small not fully formed contact surfaces. Furthermore, these gaps are "dead spots" that cause specks, e.g. contribute in polymer melts. The stains (impurities) reduce the quality of the sales products (e.g., thermoplastics).

Somewhat better temperature control properties have known static mixers that are soldered into housings or pipelines. The soldering requires a precise prepared housing or pipe and a machined on its outer diameter static mixer, so that a good and complete solder joint can come about. The mechanical preparations of the parts to be soldered are expensive and expensive. Soldered static mixers show a good contact surface to the inner tempered housing wall with good soldering. Due to the geometric structure of the static mixer, the contact surface with the heated housing surface, however, is very small, so that only a slightly higher temperature control to the product flow is possible. The enlargement of the tempered area compared to the rolled-in Static mixers are not significantly higher, so mixing joints with soldered static mixers can not be significantly reduced. The soldering is possible because of the limited Lötofenbaugröße and because of the delay of the tubes during soldering only with a small tube length (generally <2 m).

Due to the solder used, also often occur additional corrosion problems that must be considered in the application of such mixers, thus z. B. Purity and quality of a product is not deteriorated by impurities due to corrosion.

For heat transfer in liquid and gaseous substances tubes with external wound or pressed or welded technically thin sheet metal discs are still known. The outer thin disks do not have complete contact with the actual support tube, so that they are preferably used for use for temperature control of air in the highly turbulent flow region. These designs are not pressure-stable and have no mixing properties for viscous substances in the laminar flow range. Therefore, such pipe systems are not suitable for the tempering of viscous and highly viscous liquids. For improving the heat transferring properties, e.g. these outer panes and the support tube completely coated with a Niedertemperaturlot to increase product contact areas and thus increase the heat conduction. The solders used (e.g., zinc, tin) can not be used in chemical processes with high corrosion requirements, furthermore, the mechanical strength of such solders, especially at high temperature stress, is very low.

Furthermore, the temperature-controllable static mixer reactor (DE 2 839 564 A1) is known. This reactor mixes the product flowing through, wherein the mixing internals consist of meandering curved tubes. This device exists from a heatable housing, in which the mixing internals are replaced by a specially shaped meander tube bundle.

The pipe bundle consists of several parallel curved thin tubes. The ends of the tubes are welded to a flange from which the heating or cooling agent is fed to control the temperature of the Produlctstroms.

The parallel curved tubes are inserted as tempered internals parallel to the flow direction of the product in the housing. The meandering tubes are at an alternating angle in the product flow direction and extend across the hydraulic diameter of the housing. The parallel tubes in the bundle intersect each other in the axial direction of the housing, according to the known principle of the static mixer. The mixing tubes show in this construction a round to elliptical inflow cross-section, the tubes are inclined to the product flow at an angle, so that only a small distributing deflection or mixing of the product stream to be tempered takes place. Since flowed round profiles have a low mixing effect, a homogeneous temperature distribution in a highly viscous product flow in a short way is not sufficient.

The length of the insertable meander tube bundle is always a multiple of the hydraulic housing diameter. The meandering curved tubes have a large heat transferring area due to their elongated length. Through the connecting flange, the supply and removal of the liquid heat carrier takes place, which emits its energy through the product flow around the tube bundle. In particular, in the tempering of viscous substances that have heat-insulating properties, the large heating surface can not be used effectively, since the internals have no good mixing effect.

The bent pluggable tube bundles are susceptible to large pressure gradients. During start-ups or product clogging by highly viscous products high pressure gradients occur, so that the meandering curved heating / cooling tubes in the product flow direction tensile or pressure loaded and stretched. The internal heat-transmitting internals of the apparatus tend to deform and further tempering of the product by the then missing deflection of the product is no longer possible. The unwanted stretching of the tube bundle is irreparable and can lead to system downtime with high failure costs.

Due to the ideally stretched length of the individual tube and the small flow cross-section, the temperature-controllable meandering tube bundle shows a high pressure loss and a long residence time on the temperature control side. Both, pressure loss and residence time e.g. of the tempering medium in the meandering coils leads to high differences between the inlet and outlet temperature and reduces the important for heat transfer average temperature difference crucial. Due to this, the performance of such meandering tube bundles is low. In practice, a plurality of tube bundles are often connected in series, which in turn increases the investment costs, the pressure loss, the residence time of the material to be tempered and increases the assembly costs.

A uniform and gentle tempering of highly viscous, single-phase or multiphase product streams with a simultaneously low residence time can be achieved with the known systems, e.g. Static mixers with heatable housings or the temperature-controlled meandering tube bundles do not take place.

Another temperature-controllable static mixer reactor describes EP-A-1067352. This reactor consists of a channel in which the highly viscous material flow flows in the shell space of a specially arranged tube bundle and static mixers are placed in the tube bundle. The static mixer consists of crossing each other Web plates whose width, length and distance between each other are proportional to the pipe diameter and which show at an angle of 42 ° to 48 ° to the pipe axis. The mixing with this system is also not sufficient to achieve the desired uniform and gentle tempering.

This results in the need to develop a temperature-controlled static mixer, the heating channels in the product stream and has good mixing properties. The new temperature-controlled static mixer should have a low pressure drop on the heat transfer medium side, so that can be expected with large temperature differences to the temperature-controlled product flow. Furthermore, the new apparatus concept should be applicable to large hydraulic housing diameters. Additional improvements in terms of high mechanical strength, high pressure gradient capability, and the ability to use a variety of heat-conductive and corrosion-resistant materials to meet different product requirements would be advantageous.

Further requirements exist with regard to a good adaptation to different procedural problems with regard to low pressure loss on the product-contacted and tempered side, high mixing performance, a short residence time spectrum on the product side, large temperature control surface and high heat transfer performance. The invention is intended to show significant advantages for the use of viscous to highly viscous substances (viscosity 0.001 to 20,000 Pa.s).

The mechanical stability during start-up procedures or during assembly should be increased so that a higher level of operational reliability is achieved.

The new apparatus will be a compact heat exchanger, which can be installed in production plants with a low installation wall and low production costs.

The object of the invention is to provide a static mixer / heat exchanger in summary, which avoids the disadvantages of the known constructions of the prior art, allows a significantly improved temperature control with lower apparatus volume, reduces the manufacturing cost of the apparatus and a higher robustness, reliability and durability than known heat exchangers having.

The object is achieved by a mixer / heat exchanger according to the preamble of claim 1 with the characterizing features of claim 1.

The invention relates to a static mixer / heat exchanger for the treatment of viscous and highly viscous products, comprising at least one optionally temperature-controlled housing for passage of the product, in particular transverse to the main flow direction of the product at least two, preferably one behind the other arranged temperable tubes, in particular tempered by passage a heat transfer medium, are arranged distributed on the circumference of the tubes a plurality of heat exchanger webs, characterized in that the heat exchanger webs along each tube in at least two parallel layers are aligned and the webs of the various layers by an angle α of 45 ° 135 °, preferably from 70 ° to 100 °, more preferably from 85 ° to 95 ° to each other about the axis of the tube are arranged rotated and that the webs of the various layers to the main flow direction of the product by the Geh use at an angle β are of ± 10 ° to ± 80 °.

The webs of the various layers are in a preferred embodiment to the main flow direction of the product through the housing at an angle β from + 30 ° to ± 60 °, and more preferably at an angle β of ± 40 ° to ± 50 °.

Preference is given to a mixer / heat exchanger, characterized in that a web which faces this web on the pipe is arranged for each web of a layer. In the simplest case, both webs then face each other on the pipe exactly at an angle of 180 °.

Also preferred is a mixer / heat exchanger, characterized in that the webs of the various layers of webs over the length of the tube are arranged alternately. This further improves the mixing effect.

In a preferred embodiment, the webs are formed so that the webs of the various web layers are arranged along the tubes to each other in gap.

For processing higher viscosity products, in an alternative design of the mixer / heat exchanger, the distances of the webs of the various layers along the tube to each other to gap to reduce the pressure loss.

For processing higher viscosity products, in an alternative design of the mixer / heat exchanger, the distances of the webs of the various layers along the tube are chosen so that the gap between rohraxialen adjacent webs is greater than the respective web width.

The gaps increase the product flow area and reduce the pressure loss. If the gaps are smaller than the respective axial web width, the pressure loss and at the same time the heat-transferring surface of the tubes increases.

In a particular embodiment, the web width / gap ratio between two webs of two adjacent web layers is less than 1, preferably less than 0.7 and particularly preferably less than 0.5 in order to reduce the pressure loss.

Also preferred is a mixer / heat exchanger, characterized in that a plurality of tubes with webs in the housing are mounted side by side transversely to the main flow direction.

In the main flow direction of the product, the direction parallel to the longitudinal extent of the housing is referred to, which follows the product flow, with a tubular housing the direction parallel to the central axis of the housing.

In a preferred form of the mixer / heat exchanger, the tubes have tempering channels for the passage of a liquid heat carrier, wherein in the outflow of each channel, a nozzle with a reduced relative to the channel hydraulic diameter, for limiting the flow rate of the temperature control is attached.

Preferably, the diameter of the nozzle is only half as large as the hydraulic channel diameter of the respective tube.

The preferred integrated nozzle at the end of the tempering channel, in the discharge area of the tubes, reduces the flow rate of the liquid tempering medium when the channel is completely flooded. This increases the uniform flow through many parallel arranged straw pipes of the mixer / heat exchanger.

In a particularly preferred form of the mixer / heat exchanger, the housing of the mixer / heat exchanger has a separate supply and a separate dissipative housing portion for the heat transfer medium to the Supply inflow or outflow of the temperature control. In this case, there is a forced flow through the straw tubes.

The temperature-controlled mixer / heat exchanger may have a circular (hydraulic) or a rectangular cross-section, so that the cross-sectional shape of the module of the procedural need can be adjusted. The mixer has a height of length to diameter L / D <10, preferably with larger diameters, the L / D ratio is <5 and more preferably the L / D ratio is <1.

A preferred variant of the mixer / heat exchanger is characterized in that pipes which are provided with webs in a plurality of planes one behind the other (in the main flow direction), in particular pipes provided with different web forms or variants of execution, are mounted in the housing. On the one hand, this multi-stage design makes it possible to mix the mixed material more intensively on the other hand, and on the other hand, a temperature gradient along the mixing section is made possible by the different heating surfaces of the tubes standing one behind the other in the product flow direction.

By selecting the distances "a" (see FIG. 13) of the horizontal tubes, the outer webs can form mutually defined gaps. By varying the vertical pipe distances "h" gaps between the individual mixing levels can form, so that a pressure loss reduction occurs and a good welding connection of the trained in segments mixing elements with the housing is possible.

To further intensify the mixing action and tempering, a preferred mixer / heat exchanger is constructed such that the radial extent of the adjacent adjacent heat exchanger webs overlaps on adjacent tubes.

The variation of the tube spacing transversely to the product flow direction or the variation of the distances in the product flow direction enables an improvement of the mixing and tempering processes with a simultaneously smaller volume of the apparatus (hold-up). When flowing through the mixer / heat exchanger takes place in a close arrangement, an intermeshing of Temperierstege, juxtaposed or successively arranged pipes. This increases the flow rate and, as a result, the temperature control and mixing performance.

Preference is furthermore given to a mixer / heat exchanger, characterized in that the radial extent of the webs is at least 0.5 times to 30 times, preferably at least 5 times to 15 times, the inner diameter of the tube connected thereto.

Preference is furthermore a mixer / heat exchanger, characterized in that the radial webs are hollow on the tubes and the web cavity has a direct connection to the tube interior.

In special embodiments, the guide surfaces of the webs are sublime structured, so that the heat-exchanging surface is further increased and additional mixing or flow effects occur especially when passing low-viscosity materials.

The radial extent of the webs and thereby increased effective heat exchange surface while reducing the local pressure loss can not be chosen arbitrarily large due to the heat conduction properties of the pipe material used and the substance-specific heat transfer coefficient of the product to be tempered. A large radial extent of the webs can take place when the webs are hollow and the web cavity has a direct connection to the channel of the pipe. Is the process side a high dispersing performance demanded the radial extent of the webs can be made large, so that the webs overlap in different planes or webs of adjacent tubes interlock. The tubes with hollow webs can be produced in one piece by casting. Due to modern welding processes (laser welding) also a welded construction is economical.

Also preferred is a variant of the mixer / heat exchanger, characterized in that the inner wall of the tubes has a contouring to increase its surface, in particular in the form of longitudinal ribs. In analogy to the interior of the tempering tube, the outer surfaces of the tempering tubes and in particular the webs are preferably provided with contours in order to increase the product-side heat transfer surface.

Alternatively, the mixer / heat exchanger is preferably designed so that the tubes are provided with an electrical resistance heater.

If the mixer / heat exchanger is used as a heater with electrical heating cartridges inserted into the pipes, the separately formed conducting and dissipating pipes for temperature control medium are dispensed with, so that the pipes which are directly connected to the enclosing housing can be fitted on one side with the heating cartridges.

When using liquid temperature control the temperature range of the mixer / heat exchanger is from -50 ° C to + 300 ° C. Above 300 ° C, the mixer / heat exchanger can be operated with electric heating cartridges up to 500 ° C.

For carrying out catalysed processes, a further preferred design of the mixer / heat exchanger is advantageous, which is characterized in that Tubes and / or the webs are coated on their wetted surface with a catalyst.

Preferably, the tubes of the mixer / heat exchanger are integrally formed, e.g. in that the tubes are manufactured with bars in the casting process or as a forging.

The production of the pipes with bars or the pipes through casting or forming technology has cost advantages. In particular, the homogeneous material structure ensures good heat conduction from the temperature control medium flowing through to the outer surface in contact with the product and prevents cold bridges. For this reason, in particular metallic, alloyed CrNi materials, Cu compounds, aluminum, titanium, high-alloy nickel steels or precious metals are preferred materials.

The mixing action and heat exchanger function are particularly effective in a preferred mixer / heat exchanger in which the straw tubes are arranged in the housing transversely to the main flow direction of the product at an angle γ of at most +/- 15 degrees.

For special mixing tasks, a preferred mixer / heat exchanger is advantageous in which tubes are provided in the housing in several levels in the flow direction one behind the other with webs, and the tubes of the planes have differently dimensioned webs in comparison to the webs of the tubes of adjacent planes.

Preferably, a mixer / heat exchanger, characterized in that at least one behind the other arranged two parallel flocks of tubes with webs have different web shapes.

Particularly preferably, a mixer / heat exchanger is constructed, characterized in that at least one tube with webs in a plane is guided on one side with a pipe extension through the zuleitenden or dissipating tempering outside the housing and the channel of the web tube is closed on one side and at least two radial openings forms a connection from the channel of the web tube to the product chamber through which flows through the mixer / heat exchanger in order to direct an additional liquid or gaseous component into the main stream of the mixed material and to mix directly.

The direct feed of an additional substance via an outwardly extended web tube, allows the use of the mixer / heat exchanger as a reactor. On the one hand, a dye or an additive or an entraining agent can be metered in, e.g. to dye viscous products, to realize admixtures or to supply cleaning agents for a downstream purification stage. Another procedural use becomes possible when e.g. a reaction component is metered into the main stream via the flow cross section of the mixer / heat exchanger, thereby initiating or starting a chemical reaction. A possibly resulting heat of reaction, by the start of an exothermic reaction, can be removed immediately in order to keep the process isothermal.

A further preferred embodiment of the invention with plug-in temperature control units is possible if the housing of the product-side flow channel has lateral openings in the flow direction through which the tempering unit can be inserted transversely to the flow direction, so that the product-side flow cross section is completely filled with the temperature-controllable static mixer unit. Several plug-in temperature control units can then be introduced into the product-carrying channel of the housing, each offset by 90 degrees in the main flow direction. As a result, the disassembly and assembly of the device for cleaning purposes due to eg a product change is much easier. The single-sided adjustable temperature control units in this version are one-sided with heating medium supplied, so that over a prolonged extending into the tempering Kappilare the tempering the flow conditions of the heat exchanger means uniform and eliminates a further narrowing of the tempering.

In special embodiments of the mixer / heat exchanger tubes with outer webs or baffles are arranged one above the other in a U-shaped housing and welded both U-shaped housing shells to a sealed housing, so that forms a rectangular flow area for the product to be tempered (Figure 2, 2a).

Another user-friendly design of the mixer / heat exchanger is when tempering Stegrohrenden each in separate heating pockets, for the supply and discharge of the temperature, used, welded and unilaterally provided with a flange to be used as pluggable temperature control units in a customized housing.

The stacked tubes with the single-sided distributor pockets can be pushed into tempered housings as plug-in units. In such an arrangement, there is a particularly large amount of heating surface in a small space, so that a temperature-gentle temperature control takes place with a short residence time. A special advantage for the user is the possibility of cleaning the temperature-controlled mixer unit.

Preferably, several mixers / heat exchangers can be arranged one behind the other, optionally in combination with known static mixers. The mixer / heat exchanger can thereby be arranged at an angle δ of 45 to 135 °, for example of 90 ° to the housing center axis rotated to each other.

By switching several mixers / heat exchangers in series, a chemical reaction in a static-mixing reactor can be sufficiently homogenized and kept isothermal.

The mixer / heat exchanger is a powerful tempering apparatus that provides high heat transfer performance even at laminar flow rates. For this reason, the mixer / heat exchangers according to the invention are preferably suitable for the construction of backmixing-poor flow reactors, for carrying out exothermic and endothermic processes. Depending on the task can be in process-intensive reactor areas in which a reaction is started, a rapid heat exchange is desired and after dwell time regions which have less temperature-regulating effect and only a mixing is required is distinguished. Residence time ranges of flow reactors may be e.g. tempered tubes be used with known static mixers.

The main application of the invention is in the field of gentle rapid tempering of viscous to highly viscous material systems. In these applications, in addition to an effective temperature always a good and effective mixing is required to achieve temperature stability across the flow cross-section.

By being able to introduce and distribute a further substance directly into the main stream via the additional preferred material feed, additives or dyes can be mixed in so that additional mixing sections can be dispensed with in a process plant. In particular, in processes for Entrnonomerisierung of polymer melts so-called entrainers can be metered directly into the melt, at the same time takes place by the effective temperature gentle gentle heating of the polymer to a higher temperature level, without initiating a thermal product damage, so that a downstream Evaporation step as a purification step, for example, a lower-boiling undesirable component, can be performed.

Several series-connected mixers / heat exchangers can be used to design backmixing tube reactors. It can e.g. a reaction component over the additional feed of a preferred mixer / heat exchanger evenly distributed in the reaction space (product space). In endothermic reactions, the energy required for the reaction can be supplied directly in the course of the flow. If heat is generated during the reaction, the reaction heat can be dissipated directly when a refrigerant is added.

With the mentioned invention, small, compact high-performance heat exchangers for low-viscosity and high-viscosity, liquid and gaseous substances can be formed. The apparatuses show a very stable design, can be used due to the stable design at high pressure gradients, have a large heat transfer surface and work backmixing. In particular, in applications for temperature control of viscous and highly viscous single-phase or multi-phase material systems, the advantages are particularly noticeable due to small residence times.

The flow behavior of very high-viscosity material systems implies a very high pressure drop, which is why only small flow velocities are economically possible. The expert speaks of creeping currents. Here, the heat exchange between the heat transfer medium and the product is particularly bad. In this application, in addition to the large heat exchanging surface at the same time an intensive mixing process is necessary to achieve a gentle and uniform heating of the product. The temperature of the product is carried out with a corresponding arrangement of the tubes with very small residence time and a small residence time spectrum, so that in particular temperature-sensitive substances can be tempered with the mixer / heat exchanger according to the invention.

With the invention can even be dispensed with a fully tempered housing in some cases, which u. a. Investment costs are further reduced.

Due to the high conceptual flexibility of the mixer / heat exchanger according to the invention, by combining the tube spacings "a" and "h" with different land areas, variation of the number of straw tubes side by side, with each other or offset from each other, and the variation of the tube spacing transverse or with the main flow direction of the product , it is possible to meet all procedural and product-specific requirements.

The apparatus always works with small temperature differences between the inlet and outlet of the heat carrier or the coolant, so that a high power transfer when tempering and a very good use of secondary energy is possible.

The invention enables compact, pressure-resistant and inexpensive heat transfer apparatuses or backmixing poor tube reactors. The form of plug-in mixer / heat exchanger units into appropriate tempered housings results in particularly easy-to-use appliances that allow easy cleaning.

In particular, the use as low backmixing tubular reactor, with an integrated unit for uniform feed of a reaction component over the hydraulic flow cross-section of a primary main product stream offers further technical applications, which are not possible with aggregates according to the prior art.

The invention will be explained in more detail with reference to the figures by the examples, which do not represent a limitation of the invention.

Show it:

FIG. 1

a longitudinal section through the housing 6 of a mixer / heat exchanger according to the invention according to line A-A in Figure 1a and the angular offset of the webs to each other and the angular arrangement of the webs to the main flow direction.

FIG. 1a

Partial cross section and side view of the tube 1 with webs 2a and 2b of Figure 1.

FIG. 2

shows a mixer / heat exchanger with two parallel tubes 1 in a plane with webs 2a and 2a in the product flow, and the angular range α of the webs 2a and 2b and the angular range β of the webs to the main flow direction.

FIG. 2a

shows the mixer / heat exchanger according to the line B-B of Figure 2 with a zuftihrenden heat transfer chamber 4 and a laxative heat transfer chamber 5 and the angular range γ for the inclination of the straw pipes in the product flow.

Figure 3, 3a

a variant of a web pair 2a of Figure 1 in cross section.

4, 4a

a further variant of a web pair 2a of Figure 1.

Figure 5, 5a

a further variant of a flow-optimized web pair 2a of Figure 1.

Figure 6, 6a

a variant of a web pair 2a of Figure 1 with only one web 62 'and eccentric heating channel. 3

Figure 7, 7a

a variant of a web pair 2a of Figure 1.

Figure 8, 8a

a further variant of a web pair 2a of Figure 1.

Figure 9, 9a

a further variant of a web pair 2a of Figure 1.

FIG. 10

a longitudinal section along line D-D of Figure 12, by a rectangular mixer / heat exchanger unit with three adjacent tubes 1, 1 ', 1 "in a plane and a lengthened by the housing heat carrier supply chamber 4th

FIG. 11

a cross section through a mixer / heat exchanger unit, according to the line C-C of Figure 10 and integrated nozzle or aperture 3 'in the outlet region of the heating channel. 3

FIG. 12

a top view of a mixer / heat exchanger unit of Figure 10 with connections for the heat carrier supply 4 and -5 derivative.

FIG. 13

a longitudinal section through a mixer / heat exchanger unit with three in the main product flow direction successively arranged rows of adjacent tubes with different sized bars and with different tube center distances "a" or "h" and defined columns to the housing wall and between the individual tube planes for Reduction of dead spaces.

FIG. 14

shows a cross section of a mixer / heat exchanger unit with separate concentric heat supply 4 and heat dissipation region 5, further by the heat supply region 4, an infeed capillary 13 is shown as a one-sided extension of Temperierkanal to introduce an additional substance through distribution holes 14, distributed in the main product stream.

Figure 14a

shows a sectional view taken along the line A-A of Figure 14, in particular, the distribution holes 14 for uniform distribution of a feed substance in the main product stream.

FIG. 15

shows a modular mixer / heat exchanger reactor with a material introduction via capillary 13 and distribution through holes 14 for the supply of a reaction component, the arrangement having four successive mixer / heat exchanger units (9, 9a, 9b, 9c) with different L / D ratios and the mixer / heat exchanger units are rotated by 90 degrees to each other.

Examples example 1

1 shows a one-piece tube 1 in a product through which flows through housing 6, which has a land area on the outer circumference and two at a angle β = 45 and -135 ° to the main flow direction (arrow) radial mixing ribs 2a, 2a 'in a front, shown in section and a rear web area with two further webs 2b, 2b 'has. The width of the web region is chosen here such that two web layers, each with two webs 2a, 2a 'and 2b, 2b', are arranged radially offset from one another in the housing 6 along the tube axis, and they adjoin each other without gaps in their axial extent (see FIG 1a).

The shape or configuration of the webs and the web surface condition may be different. For example, the surface of the lands and the pipe may be structured by raised knobs, warts or grooves to increase the heat transferring area and to produce additional flow effects. Essentially, it depends on the process task or requirement. Examples are given in FIGS. 3 to 9. The webs may be arranged radially symmetrically (as in FIGS. 3-5) or also asymmetrically (FIGS. 7-9) on the outer circumference of the tube 1 and may show different angles relative to one another, it also being possible to combine different web shapes with one another and FIG -9 correspond with each other. The ridge shape may differ from the radial simple shape in that they additionally show a curved shape as a vane, which is particularly advantageous when the concentric regions intersect and secondary flows are forced.

Figure 3, 3a show a cross-section or longitudinal section through a tube 1 similar to FIG. 1 with two webs 32a, 32a 'which have a constant diameter and have a flattening 31 transverse to the main flow direction 21 at their ends.

In the variant according to FIGS. 4, 4 a, the webs 42 a, 42 a 'are tapered in cross-section at the end. The webs 52a, 52a 'according to the variant of FIG. 5, 5a are similar to FIG. 4, but with widened foot according to the diameter of the tube 1 executed.

Fig. 6 shows a variant of a web tube 1 similar to that of FIG. 5, but with only one web 62 'in a web position. The design according to FIG. 7 combines web shapes according to FIGS. 4 and 5 here with different radial extent of the webs 72, 72 '. In the embodiment of Fig. 8, which is similar to Fig. 7, both webs 82, 82 'in cross-section and at an angle of 170 ° C are rotated around the tube axis to each other.

In the variant according to FIG. 9, the angular offset is 90 ° C., between the webs 92 and 92 'compared with the arrangement according to FIG. 7.

Due to the shape and arrangement of the webs, the heat-transferring surface on the product-contacted side and also the flow around the pipe and thus the important mixing process can be favored. In particular, in tempering of highly viscous media, with a viscosity of greater than 1 Pa.s, a defined arrangement of the webs on the outer circumference of the tube is useful to achieve in addition to the heat transfer and an effective mixing effect. To increase the heating power, the inner contour of the straw tubes 1, which is in contact with the temperature control, can also be equipped with ribs. As a result, the heating surface is significantly increased on the heat or brine side.

The tubular shape with any number or selectively arranged web areas on the outer pipe diameter can be produced economically by casting or in a forging process, thereby always ensures that there is a complete metallic contact between the pipe and raised outer contour. In special cases, the radial webs may be hollow, so that the web cavity has a direct connection to the temperature control and everywhere constant wall thicknesses are present. Requirements regarding mechanical strength and required compressive strength are made by appropriate choice of wall thickness.

The pipes can be made of different materials to ensure a sufficiently high corrosion resistance.

The casting process allows economical production of only a specific pipe length. Larger pipe lengths must be made by connecting several pipe units with a suitable welding process.

Example 2

Another mixer / heat exchanger is shown in Figure 2 in longitudinal section. Six tubes 1 have two parallel layers of webs 2a and 2b, each with two radially offset webs 2a, 2a 'on the outer circumference of the tubes. The tubes 1 project with one end into a heat carrier feed chamber 4 and end in a heat transfer chamber 5 (FIG. 2a). The tubes 1 are welded to the supply 4 and the discharge chamber 5. The tubes 1 are at an angle γ of about 5 degrees transverse to the main flow direction 21 of the product. The tubes 1 with the webs are positioned so that the webs are positioned at an angle β of 45 degrees to the product inlet 21. The webs 2a are offset to the webs 2b at an angle α of 90 degrees.

The Zufiihrkammer 4 and discharge chamber 5 of the temperature control consist of a welded to the housing 6 pocket or a half pipe (not shown).

Example 3

10 shows a mixer / heat exchanger unit, with a rectangular housing 6 and three strut tubes 1, 1 ', 1 ".The struts 12a, 12b correspond in their design to the types shown in FIG. 3 and are along the length of the tubes 1 , 1 ', 1 "arranged in an alternating position.

In the cross section in FIG. 11 along the line CC from FIG. 10, it can be seen that two chambers 4, 5 are formed by an outer casing 15, which chambers are connected to a supply line 16 or a discharge line 17 for a liquid heat carrier (see FIG 12). The tubes 1, 1 ', 1 "are flowed through by the heat transfer medium 18 during operation, as shown in Fig. 11. At their one end, the tubes 1, 1', 1" have a constriction 3 'in the channel 3.

The mixer / heat exchanger (see cross-sectional view in FIG. 12) has a rectangular product flow area formed by the housing 6. The further housing 6 surrounding the housing 15, which is divided with partitions, forms the chambers 4, 5 for the heat transfer medium 18. Several according to FIG. 10 shaped mixer / heat exchanger units are arranged one behind the other in the flow direction and connected flush to a product line. The product flows through the units according to FIG. 10 from above (flow direction 21).

Another way of supplying and discharging the heat transfer liquid is that around the heat exchanger housing with inner struts a ring or jacket tube, which in turn has two dividers to ensure a separation between flow and return of the heat carrier (see Figure 14), slipped and welded. In a round heat transfer chamber and Housing are the temperature-adjustable tubes 1 with their webs in the Anstrulbene of the product of different lengths.

The web shape and direction, in conjunction with the horizontal pipe distances "a" or the vertical pipe distances "h" with each other form an optimal temperature-mixable mixer / heat exchanger geometry, with large heat transfer surface and high mixing effect. The tubes with the outer webs can show different pipe spacings, they can be chosen so narrow that the concentric web areas overlap and the outer mixing webs intersect with each other (see Figure 13). Thereby, the heat transferring area per unit volume can be varied and the residence time of the product can be reduced. The tubes in a plane can show different web shapes and arrangements.

Example 4

FIG. 13 shows a mixer heat exchanger arrangement similar to that shown in FIG. 10, but with two further rows of stanchions 131, 132 arranged one behind the other in the product flow direction 21.

The first series of string tubes 1, 1 ', 1 "with webs 12 a, 12 b corresponds to the shape shown in Fig. 10.

In the further rows, the tubes 131, 132 are arranged with the outer webs in such a way that the terminal webs in each case face the housing 6 in a defined gap in order to allow the flow tubes, in particular to the housing wall 6, to flow around as completely as possible (FIG. 13, level 2u ). This gap prevents the formation of dead spaces in the direction of flow, in which products can be deposited which reduce the quality of the products due to long temperature stress leads. At the same time there is an additional temperature control through the targeted guidance of the product to the temperature-controlled housing.

Example 5

According to the variant according to FIG. 14, the temperature-controllable mixers / heat exchangers can be used to distribute a component to be admixed uniformly in the product. In this application, small inlet openings 14 are introduced into the central tube 13 in the region of the webs 2a, 2b, which allow a einzumischende component via a pipe extension (13) through the Heizmittelraum to feed and uniformly introduced via the introduced openings 14 over the entire product flow cross-section (Figure 14, 14a).

A combination of several mixers / heat exchangers 9, 9a, 9b, 9c to form a flow reactor is shown schematically in section in FIG. The unit 9a here has an L / D ratio of 1.5 while the remaining units of the reactor have an L / D ratio of 0.75. The units are offset from each other by 90 degrees. The supplying heat transfer chambers 4 and dissipating Wärmeträgerkammem 5 of the mixer / heat exchanger units are all connected in parallel with the heat carrier supply. The tempering tubes 1 with webs are indicated in the units 9, 9b by broken lines and in the units 9a, 9c by the crossing points of the broken lines. It can be seen that the units in the horizontal and in the vertical plane or in the main flow direction 21 have different numbers of flow tubes for temperature control in order to effect a differentiated tempering and dispersing performance in the respective module. In the unit 9, the central tube is open only on one side (similar to the embodiment in Figure 14a) and extended by a capillary 13 on one side by the tempering 4 until outside the mixer / heat exchanger unit 9. Outside the unit 9 can now a metering pump, the not shown in FIG. 15, can be connected to, for example, a further substance (additive, entrainment agent, reactants). over the entire flow cross-section of the module or the unit to dose and distribute. Holes or nozzles 14 along the tube in the product flow ensure a uniform distribution over the flow cross-section of the unit.

Depending on the volume flow of the heat transfer medium (for example hot water, oil, cooling brine), it is necessary to provide a cross-sectional constriction or a nozzle in the outlet area of the tubes to supply the same energy density to parallel-flowed tubes. In the simplest embodiment, the inner diameter 3 of the tube in the outlet region to the dissipative heat transfer chamber is reduced in short distance, e.g. on the inner diameter 3 ', similar to that shown in Figure 11. If steam is used as an energy source, this narrowing of the inner diameter 3 of the tube 1 is not required.

Example 6 Compact heat exchanger

Compact heat exchangers have the task in a short time a medium flowing through as high as possible, ie to heat as close to the heating medium temperature, so that due to a short-term temperature load no thermal damage to the product occurs. Compact heat exchangers should have smaller apparatus dimensions, as known heat exchangers with the same performance, so that in a process engineering system only a small space requirement and thus low installation and investment costs arise. An essential feature for comparing different types of heat exchangers is the heat transfer performance, the required heat exchange area and the product-side apparatus volume. The mixer / heat exchanger according to the invention was compared with a device from the prior art (Offenlegungsschrift DE-2 839 564 A1). The investigated mixer / heat exchanger according to the invention basically corresponded to the embodiment shown in FIGS. 2 and 2a with four rather than two tubes arranged side by side transversely of the product flow direction and overall nine instead of three seen in the flow direction 21 successively arranged tube packages (see Figure 2a).

For the test, a highly viscous substance (silicone oil) with a viscosity of 10 Pa.s was selected as the product and pumped through the heat exchangers with a gear pump, so that the mass flow could be determined gravimetrically in the outlet area of the respective apparatus. The heat exchangers were connected to an electrically heated and regulated thermostat (heating power 3 kW) for the test. Water was chosen as the heat transfer medium so that the thermostat for the flow temperature at the thermostat was set to 90 ° C. The inlet and outlet temperature of the heat transfer medium and the product side were measured by means of a Pt-100 thermocouple and registered and stored on a data acquisition system. In addition, pressure sensors recorded the pressures occurring in the inlet and outlet areas of the temperature control and product side as a result of the flow losses occurring. The apparatus characteristics of the heat exchangers are summarized in Table 1. <b><u> Table 1: </ u></b> apparatus data State of the art Mixer / heat exchanger material 1.4571 * 1.4571 * Hydraulic cross section 38 x 38 mm 40 x 43 mm apparatuses length 310 mm 158 mm web width Tube 4 x 1mm 5 mm Bar areas per tube / bars per area 8 pipe parallel 8/2 Pipe diameter / inner diameter Tube 4 x 1 mm 7 mm / 5 mm Nozzle Drchm. in the exit area ------------------------------- 2.5 mm Temperature control surface of the internals 0.09 sqm 0.068 sqm Temperature control surface of the u. dissipative area (housing part) 0,00 sqm 0.012 sqm * Cr-Ni stainless steel

The apparatus data show constructive deviations. From Table 1 it can be seen that the mixer / heat exchanger has a shorter design and thus a lower product-side volume (hold-up). In addition, the mixer / heat exchanger has an effective heat transfer area of less than 0.01 square meters. Due to the design, a partial area of the housing is always tempered in the mixer / heat exchanger. For the evaluation of the test, the effective overall tempering surface has been used. From the experiments carried out, the measured temperatures and pressures, the characteristic characteristics were calculated and compared in Table 2 for both heat exchangers. The transferred heat output, the average heat transfer coefficient and the pressure loss were calculated from the recorded measured values.

Table 2 shows the calculated performance data of the heat exchangers for a constant volume flow (silicone oil) of approx. 30 l / h. <b><u> Table 2 </ u></b> Stand d. technology Mixer / heat exchanger Heat transfer performance 400W 520 W Product inlet temperature 22.6 ° C 22.5 ° C Product exit temperature 55.2 ° C 67.3 ° C Average heat transfer coefficient 98 W / sqm / K 160 W / sqm / K Pressure loss (product page) 1.5 bar 1 bar

The result of the tests confirms the higher performance of the compact mixer / heat exchanger according to the invention. With a constant volume flow and reduced residence time in the heated zone, about 120 watts more was transferred, although the product-contacting heat transfer area is lower than at the known heat exchanger. Due to the compact design of the mixer / heat exchanger, the residence time was halved.

The test result confirms a substantial improvement in the heat transfer performance with less residence time by the mixer / heat exchanger according to the invention.

Claims (18)

1. Static mixer/heat exchanger for the treatment of viscous and highly viscous products, at least comprising one housing (6) for passing the product, at least two temperature-controllable tubes (1) which are provided, in particular, with a passage (3) for passing a heat-carrying medium, the housing surrounding the tubes (1) and a multiplicity of heat-exchanger fins (2a, 2b) being mounted distributed on the circumference of the tubes (1), characterised in that the heat exchanger fins (2a, 2b) are aligned along the tubes (1) in at least two parallel layers (7, 8) and the fins (2a) and (2b) of adjacent layers (7, 8) are in each case rotationally offset to one another by an angle α of from 45° to 135°, preferably from 70° to 110°, about the axis of the tube (1) carrying the fins, and in that the fins (2a, 2b) are disposed at an angle P of from ±10° to ±80° to the main flow direction (21) of the product through the housing (6) and the temperature-controllable tubes are mounted with fins side-by-side in the housing transversely to the main flow direction of the product.
2. Mixer/heat exchanger according to claim 1, characterised in that with respect to each fin (2a) or (2b) of a layer (7) or (8) a fin (2a') or (2b') opposed to this fin (2a) or (2b) is arranged on the tube (1).
3. Mixer/heat exchanger according to claim 1 or 2, characterised in that the fins (2a) or (2b) of the different layers (7) or (8) are arranged alternatingly, viewed along the length of the tube (1).
4. Mixer/heat exchanger according to any one of claims 1 to 3, characterised in that the angle α between the fins of the different layers (7, 8) is from 85° to 95°.
5. Mixer/heat exchanger according to any one of claims 1 to 4, characterised in that the housing (6) includes supply lines (4) and discharge lines (5) for a heat-carrying medium which are connected respectively to the inlets and outlets of the passages (3, 3').
6. Mixer/heat exchanger according to any one of claims 1 to 5, characterised in that tubes (1, 1') provided with fins (2a, 2b) are mounted in the housing (6) in a plurality of planes one behind the other.
7. Mixer/heat exchanger according to any one of claims 1 to 6, characterised in that the radial extension of the respective neighbouring fins (2a, 2b) arranged on neighbouring tubes (132, 132') overlaps.
8. Mixer/heat exchanger according to any one of claims 1 to 7, characterised in that the fins (2a, 2b) of the different layers (7, 8) are staggered with respect to one another along the tubes (1, 1', 1").
9. Mixer/heat exchanger according to any one of claims 1 to 8, characterised in that the radial extension of the fins (2a, 2b) is at least 0.5 times the internal diameter of the tube (1) connected thereto.
10. Mixer/heat exchanger according to any one of claims 1 to 9, characterised in that the internal walls of the tubes (1, 1', 1") include contouring, in particular in the form of longitudinal ribs, to increase their surface area.
11. Mixer/heat exchanger according to any one of claims 1 to 10, characterised in that selected fins (2, 2a', 2b, 2b') of the tubes (1) are internally hollow and the cavity is connected to the passage (3) of the tube (1).
12. Mixer/heat exchanger according to any one of claims 1 to 11, characterised in that the tubes (1, 1', 1") are provided with a resistance heater or an electric cooling element.
13. Mixer/heat exchanger according to any one of claims 1 to 12, characterised in that the tubes (1, 1', 1") and/or the fins (2a, 2b) are coated with a catalyst.
14. Mixer/heat exchanger according to any one of claims 1 to 13, characterised in that the tubes (1, 1', 1") are arranged in a transverse direction at an angle γ of not more than +/-15° to the main flow direction of the product in the housing (6).
15. Mixer/heat exchanger according to any one of claims 1 to 14, characterised in that tubes (1, 1a) provided with fins (2a, 2b) are mounted in a plurality of planes one behind the other in the housing (6), and the tubes (1) of the planes have differently dimensioned fins (2a, 2b) in comparison to the fins of the tubes (1a) of the neighbouring plane.
16. Mixer/heat exchanger according to any one of claims 1 to 15, characterised in that the mixer/heat exchanger includes at least one medium induction tube which is arranged parallel to the tubes (1), is provided with fins (2a, 2b) of the same kind and has a plurality of openings (14) into the interior of the housing (6).
17. Mixer/heat exchanger according to any one of claims 1 to 16, characterised in that the tubes (1) include passages (3) in the outlet region of which a jet (3') of reduced diameter as compared to the passages (3) is mounted.
18. Use of the mixer/heat exchanger according to any one of claims 1 to 17 for the temperature control of viscous medium systems having a viscosity of 0.001 to 20 000 Pa.s.

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