DE10246639A1 - Multi-purpose mixer assembly for granular solids and liquids has two shafts driving ingredients in opposite directions for chemical, environmental and food processing - Google Patents

Abstract

A continually operated combined mixer and feed system for solids and liquids has a housing in the shape of an enclosed trough and a two shafts. The shafts have profiled projections driving a portion of the ingredients towards the discharge point, and a further portion of the ingredients in the opposite direction. The profiled projections are e.g. helical profiles, paddle blades. The helical profiles drive the charge towards the outlet while paddles drive the charge in the reverse direction. The trough cross-section is U-shaped, omega-shaped or tubular, preferably. omega and is temperature-regulated. One or both shafts and conveyer components are temperature-regulated. The charge is driven through the mixer at a pressure of preferably. less than 2 bar. In parallel to the mixing operation, further operations take place within the same assembly e.g. cooling, heating, isothermal residence periods, drying, sterilization, chilling and drying. The discharge is height-adjustable. The mixer has a combination of fixed and non-rotating wipers. The mixer also incorporates a vapor trap dome and vapor exhaust.

Description

The invention relates to a Mixers for the continuous mixing and conveying of solids and / or Liquids, comprising a housing in the form of a closed trough and at least one with conveyor elements occupied wave.

Solid mixers are used in a wide variety Areas needed to mix bulk goods, to temper and dry. In many cases, there are other procedural ones To solve tasks like z. B. disinfection, drying, destruction of agglomerates, discharge chemical reactions, so that high demands on the functionality of such Apparatus are available.

For Various mixers are available for the technical implementation of the "Mixing" task available often very complex apparatus geometries with several mixing waves or revolving shafts are used. Despite the availability Of the apparatus, the process engineering implementation is often still not satisfactory. So can often the ones needed Mixtures not reached within the specified mixing time, liquids not introduced homogeneously or shear-sensitive products not non-destructively are processed. Next to it is the cleaning behavior of the apparatus problematic, so that often an incomplete emptying in connection with a critical procrastination results.

Object of the present invention is a mixer for To provide solids and / or liquids, which with a simple apparatus construction is homogeneous and non-destructive mixing of the mix, and in particular an additional one Tempering, even of different zones of the mixer, the simultaneous implementation of further Procedural operations are allowed and easy to clean.

The object is achieved by a mixer according to the main claim. Special embodiment are the subject of the subclaims or shown below.

The invention relates to a Mixers for the continuous mixing and conveying of solids and / or Liquids, comprising a housing in the form of a closed trough and at least one with conveyor elements occupied rotating shaft, characterized in that the conveyor elements are arranged on the shaft so that part of the funding or Mixing elements the mix in the conveying direction promotes and another part of the funding or mixing elements promotes the mix in the opposite direction, whereby the funding elements are preferably screw, coiled tubing or paddle elements.

The mixer according to the invention can be used as a single-shaft mixer with a shaft with conveyor elements or be designed as a two- or multi-shaft mixer. Preferably the speed of the shaft (s) is infinitely variable.

The shaft is linear in the housing of the mixer rotatably installed, with the housing horizontally or at the mixer outlet erected above - stepless adjustable - aligned can be.

The mix is in the mixer from Mixer input or several mixer inputs along the conveyor line to the mixer output promoted. The direction from the entrance to the exit is called the conveying direction. The Transport in the opposite direction is called conveying in Denoted opposite direction.

The mixer according to the invention is characterized in Compared to conventional Mixers or screw conveyors characterized in that the mixer not only contains conveyor elements that the mix during transport through the mixer in axial and radial Transport direction, but at the same time a transport opposite the axial direction. There is therefore a strong backmixing in the mixing room. This is brought about by additional funding elements that so are designed so that they do not move the mix axially, i.e. conveying direction move, but in the opposite direction. This will make everyone conveying movement Part of the mix is conveyed back, which also creates new completely entered into the reactor Mix unmixed mix already premixed in the reactor. There is regional backmixing, so that an even dwell time can be guaranteed. In contrast to the extruder, the conveyance takes place essentially through the conveyor elements without additional Pressure while high pressures in the extruder of several 100 bar can be used to extract the extrudate from the reactor to press. During the Mixing and conveying pressures of less than 5, in particular, preferably form in the mixer less than 2 bar.

The residence time in the mixer can vary from from a few minutes to several hours. Especially in Case of additional Heat treatment (cooling, Heat, Drying) are residence times of 3 to 6 h, based on a conveying length of 6 m advantageous (1/2 to 1 h per meter).

The shaft particularly preferably points Screw elements on, designed as a fully threaded screw or several fully threaded screw belts (this is a screw belt, which is mounted on the shaft by means of spacers), and / or several Auger segments or auger belt segments. The snail elements take care of that Mixing and funding of the mix in the main conveying direction.

The fully threaded screws or fully threaded screw belts can also have openings, in particular oval openings. The breakthroughs can be made by laser. The openings can make up 10 to 70% of the production area (s). As special It has also proven to be advantageous if the outer contour of the screw elements is sawtooth-like, at least in the outlet area, possibly with exposed saw teeth, which are used for scraping in the outer casing area.

Coiled tubes are also possible, preferably additionally to be used for the screw elements. The coiled raw have the shape of a spiral.

In another embodiment has the shaft mounted on the shaft and perpendicular to the axis of rotation aligned discs on, which with paddles, preferably adjustable Paddling on the outer perimeter are provided, wherein the majority of the paddles are aligned with the axis of rotation is that this is a promotion in the main conveying direction effect and a smaller proportion of the paddles opposed is to promote in the opposite direction.

It is also possible to provide several fully threaded screw belts, wherein at least one fully threaded screw conveyor conveys in opposite directions.

Furthermore, the wave or the other mixing elements preferably paddle elements that at least some funding effect in the opposite direction. These are preferably on the outer diameter the screw elements, coiled pipes or discs, can but also be mounted on the shaft itself. The paddles are preferred rotatable, i.e. adjustable and lockable. The Paddles take the height preferably up to about 30% of the length of the disk radius or Screw radius on, measured from the shaft to the radially outermost one Edge of the screw, tube or disk.

The paddles are preferably sufficient their radially outward Edge on the inner housing wall to get there as a housing wall scraper to act and are shaped accordingly with regard to the upper edge. The padels preferably have an oval shape.

For cleaning and removing Product buildup on the mixing tools, especially on the temperature-controlled ones Disks, for example Scraper can be provided as cleaning elements by the fixed Housing inner wall of the trough laterally between the panes or between the segments protrude into the mixing room. For example, on the inner wall of the housing attached scraper holders each hold two scraper blades that scrape the mix from the disc elements and / or from the shaft. The side elements of the scrapers can be radially adjustable, so that the penetration depth and thus the cleaning efficiency varies can be. This can short cleaning intervals can be realized.

In contrast to mixers that are in the Can work in batch mode higher Space-time yields can be realized. At the same time, more Process steps and for this needed Equipment saved, which further shortened the manufacturing process and for a cheaper one Production leads. At the same time, due to the continuous way of working the same amount of mix processed in a smaller reactor become. This will add Space and energy saved. Long service life of the mixer between the mixing processes, the for Cleaning and filling are avoided.

The housing of the mixing device is is preferably designed as a U-trough, Omega trough or tubular trough, particularly preferred as an omega trough. Taking omega trough in the sense of Invention is. thereby a housing understood that in its form essentially that rotated by 180 ° greek letters omega (Ω) with the upper flat edge. The upper part of the trough can the assembly of a dome and vapor deduction serve.

In the case of a pure mixed task is that Filling volume on mixed material, preferably approx. 30 to 70% of the mixing space available in the mixer, with additional thermal treatment preferably up to 100%.

For the process stages that can be achieved with the mixer, such as heating, cooling, drying, Mixing, conveying, Crystallize, coat, linger, sanitize, classify partly also run in combination is according to a further embodiment the invention a special housing has been developed. The housing The structure of the mixer is always the same, only the geometry of the actual mixing room is changeable or parameterizable. For this, the conveying and mixing shaft is connected with process control, i.e. Speed, temperature, conveying speed (= Flow rate) adapted to the respective product. The mixer is preferred designed so that in the same housing shafts with different geometries can be used. So only the shaft has to be exchanged when changing the mix and it can then be in the same mixer in its physical Texture completely different mixes are processed.

In a special embodiment of the invention, the housing can be tempered. The temperature control of the housing is understood to mean that the mixing space is at least partially surrounded by a jacket and this is temperature-controlled. At least one shaft and / or the conveying elements are preferably tempered. In addition to the mixing elements, the jacket of the mixing room should also be used for temperature control. The housing, the shaft or the shafts and / or the conveying elements can each be designed to be temperature-controllable separately from one another. It is also possible to temper only some of the conveying elements, for example in certain zones of the mixer, or to temper the conveying elements differently along the conveying path, for example initially by means of different cooling or hot medium accesses heat and then cool. For example, a two-stage structure is conceivable, ie the heating / drying zone is immediately followed by a cooling zone. In this way, the thermal stress on the mix should be reduced.

Realizing cooling directly in the mixer is possible because of the long dwell time of the product in continuous operation can be achieved. To set the dwell time in a targeted manner, according to the invention the special design of the funding elements, additionally the discharge side of the mixer, i.e. the mixer outlet is hydraulic height adjustable accomplished his. about a minor one Employment of the mixer becomes the conveying behavior of the mixer and thus the dwell time changes.

The mixer is preferably off Steel made, depending on the requirement, the corresponding Steel can be used, from black material to stainless steel, boiler steel up to high heat resistance and / or high abrasion resistant steels.

In the mixer according to the invention can be preferred parallel to the mixing process, further process operations such as cooling, heating, isothermal lingering, drying and sanitizing can be carried out. While of funding in continuous operation additionally in the mixer Temperature, particle compositions, pressure, humidity and residence time be set specifically.

The mixer is preferably used for Mixing or treating solids and bulk materials used. The mixer can also be used to mix liquids or liquids and solids are used, such as the cereal Honey is added, or technical resin mixtures.

The mixer according to the invention is for very diverse applications and different products in the fields of environment, chemistry, food use. Examples of applications are the drying of whitewash in the environmental industry, drying silica gel in chemistry, the Mixing cereal in the food sector as well as mixing, drying and pressing cellulose, for just a few possible uses to call.

The mixer has a high mixing efficiency and optimized heat transfer behavior on. Due to the modular design, a housing in which different shaft geometries various mixing tasks can be carried out. The Mixer can be configured, for example, as a single-shaft horizontal mixer his. As mixing elements can in this case temperature-controlled discs are used on the shaft, on those outside Return feed paddle are attached. The paddle position is adapted to the mix, in order to adjust the throughput and the dwell time in a targeted manner by partially restituted and returning Paddle.

Due to the continuous operation can in the mixer according to the invention also such products are processed which are responsible for the heat transfer and the mixing effect need high speeds and the for Product drying and cooling require long product residence times in the mixing room, i.e. such Use cases, the high mixing intensities require for long dwell times. This means for batch mixers always low space-time yield.

Various examples are given below embodiments of the mixer according to the invention described:

A wave thermal mixing reactor

With the wave thermal mixing reactor is a mixer for conveying and thermal treatment of less adherent media. Liquid products or bulk goods can be treated become.

It is essential that at a defined product throughput with a certain thermal Performance sufficient effective heat exchange surface at the same time good mixing and, if necessary, also a sufficient waiting time of the product can be achieved in the system. This will be a combination from fully threaded screw, one or more coiled tubes and Paddle elements used.

Different heating or Cooling media - such as Saturated steam, thermal oil, Water, brine or liquid nitrogen be used. The selection of the heating or cooling media is based on the application and the one you want Temperature range.

Einwellenscheibenprozessreaktor

The mixer according to the invention can also be used as a single-shaft process reactor equipped with a heated shaft and heated disks and conveyor paddles accomplished his. The single-shaft process reactor is one maximum heat exchanger area per Reactor volume, one if possible huge Product retention time in the reactor and mixing optimized. The process reactor can due to self-cleaning properties and applicable scraper for higher viscosity products that tend to cake are used.

Two-wave process reactor with fully threaded thermal wing

The wave process reactor was developed especially for viscous products with problematic rheological properties. Here it is important to continuously clean the heat exchange surfaces and loosen the product from the free spaces between the conveying elements. A robot drive offers the additional for each shaft che Possibility of continuous cleaning of the spaces between the conveyor elements such as screw flights or paddle elements, the shafts being electronically controlled relative to each other so that the shafts are operated - preferably continuously - sometimes with a high and sometimes with a low speed difference, in order to interlock the screws To cause stripping of buildup. Depending on the product properties, different shafts can be used with adapted conveyor elements.

1 shows a schematic longitudinal section through a mixer.

2 and 3 show different sections through the apparatus 1 , On 3 The presence of the tubes in the area of the shaft shows that a separate temperature control of the disc blades is provided in the area of the product inlet.

4 and 5 show separately heated panes. 6 and 7 those that are heated together with the shaft.

8th the exterior of the mixer is shown in the set-up form (mixer outlet above).

Claims (17)

Mixers for the continuous mixing and conveying of Solids and / or liquids, comprising a housing in the form of a closed trough and at least one with conveyor elements occupied rotating shaft, characterized in that the conveyor elements are arranged on the shaft so that part of the conveyor elements the mix in the conveying direction promote and another part of the funding elements promotes the mix in the opposite direction on the same shaft. Mixer according to claim 1, characterized in that the conveyor elements screw, coiled tubing and / or paddle elements. Mixer according to one of claims 1 or 2, characterized in that the mixer at least two Has waves. Mixer according to one of the preceding claims, characterized in that the shaft screw elements, formed as a fully threaded screw, one or more fully threaded auger belts, several auger segments and / or screw conveyor segments, with in the area of the outer circumference the screw elements and paddle elements attached to them, the screw elements in the conveying direction and at least partially convey the paddle elements in the opposite direction. Mixer according to one of the preceding claims, characterized in that the housing as a U-trough, Omega trough or tubular trough, preferably as an omega trough. Mixer according to one of the preceding claims, characterized in that the housing is tempered. Mixer according to one of the preceding claims, characterized in that at least one wave is tempered. Mixer according to one of the preceding claims, characterized in that the conveying elements are tempered, preferably the screw elements. Mixer according to one of the preceding claims, characterized in that the promotion of the mix low pressure, preferably at pressures less than 5, in particular less than 2 bar. Mixer according to one of the preceding claims, characterized in that further process operations in parallel to the mixing process Mixer performed can be preferably cooling, Heating, isothermal lingering, drying and / or sanitizing, especially cooling, heating and / or drying. Mixer according to one of the preceding claims, characterized in that the discharge side of the mixer is adjustable in height is executed. Mixer according to one of the preceding claims, characterized in that the mixer is fixed and not has rotating wipers. Mixer according to one of the preceding claims, characterized in that the mixer has a vapor dome and has a vapor deduction. Mixer according to one of the preceding claims, characterized in that the mixer mounted on the shaft Disc elements, preferably temperature-controlled, which may are equipped with paddle elements, at least some of which are paddle elements promote in the opposite direction. Mixer according to one of the preceding claims, characterized in that the mixer on the outer outline the saw elements located saw teeth, preferably with a width of 5 to 50 mm and a height of 5 to 20 mm. Mixer according to one of the preceding Claims, characterized in that the mixer has two shafts, of which one shaft is operated at a constant speed and the other shaft is temporarily rotatable within a mixing process at a higher and temporarily at a lower speed and the shafts have intermeshing screw elements which may are filled with paddle elements. Process for mixing and, if necessary, tempering mixed materials a mixer according to one of the previous claims.