EP0613721A2 - Method, its application and device for grinding and treating recycling products - Google Patents

Abstract

The new invention proposes guiding recycling products in the form of e.g. small pieces (13) of material into a comminuting space (8) at the same time as hot gases (3). In this space, an impeller (1) is arranged, which comminutes the pieces (13) of material to a size of 2 - 3 mm and throws them into a swirling chamber (2), in which a multiple recirculation takes place. The adequately comminuted parts are conveyed with the drying gases (3) into a drying tower (15) and extracted via a cyclone. The drying tower is designed as a rising sifter (16) and has a return duct (18) for oversizes. The method and the device are in particular suitable for the processing of e.g. egg shells, glass recycling waste, and also a large number of organic recycling products such as the most varied agricultural products and other organic waste of animal origin. The end product can be separated into very different material categories or e.g. used as feed. <IMAGE>

Description

The invention relates to a method for crushing and processing, for example. of waste of animal and / or vegetable origin. The classic process engineering e.g. For the drying of solid substances, it is generally assumed that the starting product is shredded into a particle size that is optimal for drying. In many cases, the good particles have a given shape, size or structure that must not be destroyed by drying. In the second case, the drying system is equipped with correspondingly gentle moving or conveying means. This results in either a high expenditure for the preparation or very long preparation times. Both make installation and operating costs more expensive. In the field of recycling product recycling, such solutions are out of the question, otherwise the end product will become too expensive.

For decades, the expert opinion had prevailed that the recycling products should be divided into organic and inorganic materials and processed separately. In the case of organic products, a changing composition was always accepted, although this means that the preparation, e.g. is usually not optimally feasible through composting. In the case of inorganic materials, depending on the type of substance and the quantity of the corresponding recycling products, processing that had specialized in each type of waste had prevailed.

The invention was based on the object of reducing the outlay for processing a large part of recycling products, in particular also for waste of animal and / or vegetable origin, which as a rule have a very high water content, for example. for meat waste or vegetable or vegetable waste. Another part of the task was to obtain optimal end products with uncomplicated means.

The solution according to the invention is characterized in that the starting product is mechanically impact crushed in a hot gas stream and spun with the hot gas stream into a whirling chamber, with enough comminuted parts being discharged from the hot gas stream and separated therefrom, but insufficiently comminuted parts being recirculated in the whirling chamber and repeatedly being impact crushed.

In a particularly advantageous embodiment, the starting product consists of different substance categories, with at least two substance categories, e.g. separated by sieving or sifting. The inventor has recognized that in many cases the waste is composed in such a way that comminution without preparation cannot lead to the goal. It is known that in so-called high-level milling, for the production of semolina and flour, the grain is added to the grain beforehand by repeated grinding and sieving, so that the grain shell acquires an elastic behavior during a 1 - 2 day rest period of the whole grain mass. The grain interior, on the other hand, maintains an emphatically crystalline behavior (starch crystals). It has now been shown that, analogously to this, when a hot gas stream is used according to the invention on broken eggshells, two fractions can be separated with a high degree of purity and a fraction egg shell and a fraction egg skin can be separated. The egg skin retains a flat shape, similar to the grain shell in high-milling, whereas the hard egg shell is crushed into lime flour. Leave over a sieve the lime powder as sieve diarrhea and the eggshell as sieve rejection separate very easily. Interestingly, bottles or broken glass could also be processed analogously according to the invention as recycling products. All foreign objects, such as Plastic-aluminum closures and labels could be separated from the cleaning glass. The glass itself was reduced to sand. The glass was pulverized using high impact crushing speeds. Here, too, the separation was very simple using classifying sieves.

According to a particularly advantageous embodiment, the starting product can have a high water content of, for example. 30% - 60% and with the hot gas flow e.g. be dried to a storage humidity. The vortex chamber is preferably formed directly above an impact crushing rotor and under the inlet part of a drying storm, the insufficiently crushed parts repeatedly falling back on the impact crushing rotor by gravity until they are sufficiently crushed.

According to a further very advantageous design idea, so-called wet products, preferably wet recycling products, such as waste of animal and / or vegetable origin (optionally mixed with dry products), can be used to produce a meal or semolina as a finished or semi-finished product. Potato and sugar beet pulp and other crops or fruit can be processed as wet raw materials (e.g. cabbage, cabbage, fruit such as apples, pears), as well as canteen kitchen waste and residues from cider plants. Mixed grass, clover, reed grass can be used as "chopped grass". Cereals, maize, cereal by-products, bran or other dry, organic substances suitable for feeding to animals can be added to the starting product as dry products. This allows the adjustment of the water content for the starting product and for upgrading the end product. The wet raw materials and the dry products are preferably mixed to an average water content of 30% to 60% and a desired nutrient content and then, possibly after preheating, processed according to the invention. With the new method it is possible e.g. Mix potatoes or beet pulp (leached or unleached) and chopped grass with dry products, so that with 30% - 60% moisture of the starting product, a high-quality compound feed could be produced, which is not known in this way. It was interesting in all cases to observe that segregation, for example that the comminuted raw materials are carried out in a staggered manner, does not take place. The flour or semolina produced is both a finished product and a semi-finished product. Flour is bagged and sold as animal feed. Semolina can be pressed into feed cubes in a feed press. The shelf life of the end products flour, semolina or feed cubes corresponds to the shelf life customary for feed. According to a further embodiment, the material to be dried can be separated from the hot gas stream and passed through a separation device and a coarse fraction can be recirculated into the area of the impact comminution.

The new invention is based on the invention that the comminution work is usually only an intermediate step that is technically necessary. The shredding requires a lot of energy if it takes place before or after drying. But this is in poor relation to the benefit. It is therefore proposed to put the waste in piece form directly into the hot gas stream and to carry out the comminution work in the hot gas stream itself which accelerates the drying process by repeated recirculation and impact crushing of the insufficiently comminuted parts. This has the great advantage that for the shredding work required energy can be kept small because the material is crushed wet and the heat generated can be used directly to accelerate drying.

The invention further relates to a device for carrying out the method and is characterized in that it has a centrifugal wheel with a hot gas supply channel and an enlarged swirl chamber arranged directly above it, which continues as a riser and is connected to a separating device.

Preferably, the hot gas supply channel, which is arranged vertically from top to bottom, is directly upstream of a flammable space of a controllable oil or preferably gas burner, arranged from the bottom upwards, in such a way that the heat effect of the flame cannot act directly on the material to be dried, and in the region of the swirl space an initial temperature of e.g. 400 ° C or higher is adjustable. The drying tower is advantageously designed as a climbing sifter. A flow rate of the drying gases corresponding to the floating speed of particles smaller than 2-3 mm and a temperature of the drying gases of 400 ° C. or more are selected for odor-intensive substances, preferably from 500 ° C. to over 600 ° C. It can also be advantageous if, for example, part of the fat is previously separated from meat waste with an excessively high fat content and at the same time the entire waste mass is preheated. Instead of separating the fat from meat waste with a high fat content beforehand, such meat waste can also contain 20 - 50 vol. % ground grain (or its sub-products) are added, which absorbs the excess fat.

The separating device can have a cyclone for separating the dry material from the drying gas, furthermore a subsequent sieving device, which is preferably either via a return device for a coarse sieve fraction is led directly into the vortex room or back to the inlet for the starting product. The swirl chamber is preferably arranged directly above the centrifugal wheel (1) and has guide walls for local recirculation of lumpy parts. The vertical sifter can be connected to the swirl chamber for the recirculation of oversized parts via a return channel separated by a lock. Advantageously, the gas treatment and the drying are set up as essentially vertically extending and compactly arranged process areas which are designed as an assembly in the sense of transport units. Viewed in a horizontal section, the burner chamber, hot gas supply duct and the riser form an angle in which a separator designed as a cyclone is arranged.

The invention further relates to the use of the method for preparing egg shells, for producing a fraction of egg membranes (cuticles) and lime (shell); or for the processing of recycled glass, bottles or broken glass, for the production of a granular glass fraction and the other foreign bodies or for the processing of organic products such as potato or sugar beet pulp as well as, if necessary, chopped grass and dry products for the production of animal feed. For the individual product categories, only a special injection has to be selected. Pretreatment or pre-shredding is e.g. not necessary in the case of glass preparation. The resulting glass grains are smaller than the contaminants such as label residues (shredded paper), aluminum or plastic closures. The glass grains are removed together with the impurities from the cyclone and then separated by sieving. The glass powder obtained as sieve diarrhea can be used in road construction or for the production of artificial stone floor slabs. The contaminants that form the screen discharge are stored or burned in landfills.

In egg processing factories, the egg shells are no longer processed but crushed and taken to the field. According to the invention, they are now comminuted with the hot gas stream without pretreatment. The resulting lime powder and the egg skin are discharged together by the wind sifting and the cyclone. After the cyclone, the mixture of lime powder / single skin is separated over the drum screen. Sieve diarrhea is the lime powder; Sieve the egg skin. The lime flour is used as a raw material for the animal feed industry or as an auxiliary for other industries (e.g. tannery). The egg skin is ground into flour and can be used as an additive for pet food.

In the following, reference is now made to FIG. 1, which represents a preferred exemplary embodiment. At the heart of the device is a rotating centrifugal wheel 1 with a swirl chamber 2 arranged directly above it. The drying gases 3 are brought to the desired temperature by an oil or gas burner 4, for this purpose the burner flame 5 opens directly into a flame chamber 6 which extends vertically upwards and which is connected to a hot gas feed chamber 7 which is directed vertically downwards and directly into a comminution chamber 8 opens. Pieces of waste 9 are, if necessary, reduced in a reducing device 10, for example in the manner of a meat grinder, and metered via a feed line 11, fed directly into the comminution space 8. In addition, the waste 9 can be brought to a higher temperature by means of a heater 12. This supports the inherently less favorable heat transfer from the drying gases to the items to be dried, with the aim of drying the items very quickly, in order to avoid harmful biological or chemical changes to the products as far as possible. The lumpy good parts 13 are comminuted by the centrifugal wheel 1 to a grain size 14 of approximately 2-3 mm.

The vortex chamber 2 opens directly into a drying tower 15, which on the one hand has a riser 16 and additionally a plurality of guide walls 17 or correspondingly formed channels and on the other hand a return channel 18. The return duct 18 is blocked by a lock 19 for direct passage of the drying gases 3, so that the oversized parts are specifically returned to the swirl chamber 2. This results not only in the swirl chamber 2 itself, but also with the inclusion of the drying tower 15, an intensive recirculation of the material to be dried until the particles 20 no longer exceed a desired particle size. By choosing the correct gas velocity VG in the upper region of the drying tower 15, the corresponding fraction with the hot gases can be passed into a cyclone 21, in which the drying material 22 is separated from the hot gases 3 ′ or conveying gases saturated and cooled with water. So that the amount of drying gases 3 and the temperature of the drying gases can be selected independently, the fuel supply can be regulated by means of appropriate control means and the amount of air can be adjusted by a fan 24. The aim is to ensure that the entire facility is under vacuum in all operating states and that no gases escape. All processes are controlled by a controller 25. The dry material 22 is passed via a lock 26 into a drum sieve 27, from which the fine fraction is fed to corresponding storage containers or further processing via a discharge line 28. The screen rejection can be conveyed back into the swirl chamber 2 via a return line 29.

The drum screen 27 can be replaced by an equivalent device. Instead of this, the dry material 22 can be fed from the lock 26 into a suction line which is acted upon by a fan and which also sucks in ambient air together with the dry material 22 in the area of the lock 26. Between the lock 26 and the fan, a second cyclone is connected to the suction line, which the dry material 22nd separates. The ambient air drawn in by the suction line at the lock 26 cools the dry material 22 removed from the cyclone 21 so intensively that it can be fed directly to a further processing station, for example a bagging device, after the second cyclone. A coarse part separator can be integrated in this equivalent device, from which coarse parts are conveyed back into the swirl chamber 2 via a return line (analogous to the return line 29).

The whole system has the particular advantage that all parts of the material to be dried only stay in the respective zone for as long as is absolutely necessary for shredding or drying. In relation to the original condition and the drying time required - which is much longer for large parts than for fine parts - there is an ideal dwell time for the goods, especially the fastest dried fine parts are removed immediately and no longer burden the drying process.

Claims (15)

Processes for shredding and processing recycled products,
characterized by
that the starting product is mechanically impact-crushed in a hot gas stream and flung with the hot gas stream into a whirling space, with enough comminuted parts being discharged from the hot gas stream and separated therefrom, but insufficiently comminuted parts being recirculated in the whirling space and being repeatedly crushed. Method according to claim 1,
characterized by
that the starting product consists of different substance categories and after processing in at least two substance categories e.g. is separated by sieving or sifting. The method of claim 1 or 2,
characterized by
that the starting product has a high moisture content of e.g. Has 30% - 60% and is preferably dried to a storage moisture with the hot gas stream. Method according to one of claims 1 to 3,
characterized by
that the vortex space is formed directly above an impact crushing rotor and under the inlet part of a drying tower, the insufficiently crushed parts falling back on the impact crushing rotor due to gravity. Method according to one of claims 1 to 4,
characterized by
that the starting product, so-called wet product or fat product, is preferably wet or high-fat recycling products such as waste of animal and / or vegetable origin, optionally mixed with dry components, from which a feed meal or feed semolina is produced as a finished or semi-finished product. Method according to claim 5,
characterized by
that the dry components are 20 to 50 vol. % are ground grain or its sub-products. Method according to one of claims 1 to 6,
characterized by
that the material to be dried is separated from the hot gas stream and passed through a separation device and a coarse fraction is recirculated into the area of the impact comminution. Method according to one of claims 1 to 7,
characterized by
that the material to be dried is passed through a flow channel and mixed therein with ambient air for cooling. Device for carrying out the method according to one of claims 1 to 8,
characterized by
that it has a centrifugal wheel (1) with hot gas supply channel (7) and an enlarged free swirl chamber (2) arranged directly above it, which continues as a climbing sifter (16) and is connected to a separating device (21). Device according to claim 9,
characterized by
that the separating device (21) has a cyclone for separating the dry material (22) from the drying gas (3 ') and a subsequent sieving device (27), which preferably has a return device (29) in the vortex chamber (9) for a coarse sieve fraction. Apparatus according to claim 10,
characterized by
that the separating device (21) has a cyclone for separating the dry material (22) from the drying gas (3 ') and then a pneumatic cooling section and a further separating device with preferably a return device (29) in the vortex chamber (9) for a coarse fraction. Device according to one of claims 9 or 10,
characterized by
that the vortex chamber (21) has guide walls (17) directly above the centrifugal wheel (1), for local recirculation of oversized parts, the riser (16) preferably having a return duct (18), separated by a lock (19), into the vortex chamber ( 2), is connected. Device according to one of claims 9 to 12,
characterized by
that the gas treatment and the drying are designed as essentially vertically extending and compactly arranged process areas. Device according to one of claims 9 to 13,
characterized by
that it is designed as an assembly, the flame chamber (6), the hot gas supply channel (7) and the riser (16) forming an angle in a horizontal section, in which a separator (21) designed as a cyclone is arranged. Application of the method according to one of claims 1 to 8, for the preparation of egg shells, for the production of a fraction of egg membranes (cuticle) and lime (shell); or for the processing of recycled glass, bottles or broken glass, for the production of a granular glass fraction and the other foreign bodies; or for the preparation of organic products such as potato or sugar beet pulp and / or chopped grass, optionally mixed with dry products for the production of animal feed.

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