Device for introducing atmospheric oxygen into a moist solid

Abstract

Device (1) for introducing atmospheric oxygen into a moist solid (30) comprising - a cylindrical drum (2) arranged to rotate about an axis of rotation (3), - an inlet device (8) on the drum (2) for introducing the solid (30), - a discharge device (9) on the drum (2) for discharging the solid (30), - at least one aeration device (15) for introducing atmospheric oxygen into the solid (30), characterized in that the aeration device (15) comprises: - a fixed outer supply air duct (16) arranged on the drum (2), wherein the fixed outer supply air duct (16) surrounds a rotatably encircling outer surface (18) of the drum (2) transversely to the rotation axis (3) and in a rotation angle segment (α) around the rotation axis (3) with a form fit, and - at least one air inlet opening (19) which rotates with the rotation of the drum (2) through the outer surface (18) of the drum (2), so that when passing through the rotation angle segment (α) the at least one circumferential air inlet opening (19) comes into open flow contact with the fixed outer supply air duct (16) by overlapping.

Description

[0001] The invention relates to a device for introducing atmospheric oxygen into a moist solid, preferably into partially dewatered liquid manure, comprising: a cylindrical drum arranged to be rotatable about a preferably horizontal axis of rotation; an inlet device on the drum for introducing the solid; a discharge device on the drum for discharging the solid; at least one aeration device for introducing atmospheric oxygen into the solid.

[0002] The device according to the invention can be used to treat, in particular, partially dewatered liquid manure, preferably cattle manure, in order to obtain hygienic bedding.

[0003] The prior art, for example EP 1 817 532 B1, describes that cattle manure is partially dewatered using separators and then sanitized in rotating drums. This allows bedding to be recycled from the manure. Corresponding regulations (for example, Regulation EC 1069 / 2009) of the European Parliament prescribe sanitization at 70 °C and a residence time of one hour for the use of such a material. DE 10 2014 212 196 A1 describes a process for the aerobic microbiological heating of pourable, moist organic solids and a corresponding device that enables cost-effective operation for the purpose of safe and energy-efficient heating of the solid, in particular for sanitizing bedding. Since the present invention relates to a further development of the subject matter contained in DE 10 2014 212 196 A1, reference is made here to this document.

[0004] DE 20 2012 012 027 U1 discloses a device for drying, mixing, treating and / or refining solid and / or liquid substances or substance mixtures, with a drum which is rotatable about a longitudinal axis for receiving the substances or substance mixtures, wherein the drum has an inlet opening and an outlet opening for receiving and discharging the substances or substance mixtures, wherein the drum has an inlet and an outlet for an air flow, and wherein the drum is arranged in a housing, characterized in that the drum is arranged within the housing in such a way that part of the air flow flows through the drum in a substantially axial direction from the inlet to the outlet and part of the air flow flows between the drum and the housing, wherein the drum is heated from the outside by the air flow.

[0005] DE 10 2013 219 275 A1 relates to a device for the aerobic microbiological heating of pourable, moist organic solids, preferably partially dewatered liquid manure. The device comprises a rotatably mounted drum, an inlet device on the drum, and a discharge device on the drum. The inlet device is designed to inlet the solids. The discharge device is designed to discharge the solids from the drum. Furthermore, at least one perforated tube is provided for introducing oxygen, in particular atmospheric oxygen, into the solids. The tube extends within the drum and is connected to the drum in a rotationally fixed manner.

[0006] In the current state of the art, the task of introducing oxygen, particularly as aeration with atmospheric oxygen, into a moist solid continues to play an important role, particularly, but not exclusively, in the context of the pasteurization of solids such as partially dewatered manure. The approach of aerating in rotating drums, in which the moist solid is present as a bulk, has proven to be advantageous on an industrial scale compared to other conceivable approaches, such as the mixing of additives such as zeolites, acids, flocculants, and the use of mechanical devices based on the principle of microwaves, high voltage, or an applied vacuum, which regularly entail disadvantages in terms of design effort and the required safety technology during operation.The latter alternative processes are often unsuitable for large-scale use due to the resulting cost disadvantages alone. Furthermore, the process costs increase when introducing additives mentioned above, for example, due to the additional raw material costs plus the costs of silo maintenance and material flow.

[0007] In this respect, the fundamentally advantageous processes that aerate the moist solid in a drum receiver pose the technical challenge of achieving a high throughput, which in turn requires a high filling level of the drum with the moist solid, while simultaneously achieving a high exchange interface for the oxygen transfer from the gas phase to the solid phase. The efficiency of such a process-engineering aeration unit is known to result from the interplay of many fundamental physical processes of mass and, if applicable, heat transport, in particular diffusion in the macroscopic phases and at interfaces, possibly in porous voids in the case of agglomerated solids, absorption / adsorption, dissolution behavior, possibly chemical reactions at solid surfaces, wetting, drying behavior, etc.

[0008] In the case of a rotating drum, one specific disadvantage plays a major role, which has been discovered many times in operation and is sometimes so prohibitive that it rules out some applications, particularly in pasteurization tasks: In the bulk of moist solids that rotates and circulates with the drum rotation, a solid, non-renewing, cylindrical, rolling cylinder often forms in the center of the drum around the axis of rotation. This effect is observed more frequently at the desired high fill levels, which in turn are necessary for appropriate throughput in terms of economical dimensioning of the drum and design of the entire system. This rolling solid cylinder acts as a compacted core volume in the bulk and forms a boundary zone that is difficult to overcome for diffusion into the interior.As a result, material transport, particularly the intentional introduction of oxygen, but also any desired heat transport, occurs only to a limited extent or even not at all inside this solid drum. However, particularly with regard to aeration processes for the purpose of pasteurization in the case of a microbiologically colonized solid, it is essential, for example, to ensure that every small volume element experiences the same process history with regard to the prescribed sanitation residence time of at least one hour at a minimum of 70 °C by setting an optimal filling level of the drum with solids.

[0009] In particular, it was found that in countries with geographically high humidity, heating in the drum is more difficult than in dry regions. From a thermodynamic perspective, the core cause of this is the enthalpy of the water content carried in the air phase. Therefore, a further object of the present invention is to be able to significantly reduce the volume flows of the aerating gas phase by increasing the oxygen transport, in the sense of an uptake rate or an overall uptake degree after the residence time of the bulk. Only with such a measure can the entire device and the associated peripherals, such as a fan for the supply air, be dimensioned smaller. Smaller dimensions, in turn, regularly lead to an advantageous reduction in overall costs, both in terms of device construction as an investment and in operation.

[0010] This already suggests the disclosure of DE 10 2014 212 196 A1, in particular Fig. 3, proposes an advantageous solution to this problem, whereby optimized mass and heat transport occurs throughout the solids in the bulk drum, and even a uniform residence time distribution per volume element can be achieved. However, the solution disclosed therein has the significant operational disadvantage that the rotary coupling described therein and the perforated, movable ventilation pipe with the movable cover to be inserted into the drum are structurally complex in this arrangement, which in turn entails high costs. In this respect, although this arrangement is fundamentally feasible, it is somewhat disadvantageous in terms of investment, operating, and maintenance costs.A further practical disadvantage arises from the complex rotary joint design with preferential control, which results in a rather narrow dimensioning range in which such an arrangement can be reasonably constructed, namely less so for smaller pilot plants. In this respect, practical disadvantages of this solution often arise from the need to scale up processes, which should be carried out carefully, especially in the case of microbiological process applications. A further disadvantage is that the air intake is distributed over the entire length of the drum and thus not only targeted in those bulk areas where the air is actually needed. Furthermore, areas with varying levels of ventilation arise. The resulting different pressures prevent the desired flow of the solids through the corresponding areas of the drum.

[0011] Therefore, a central objective of the present invention is to ensure an increase in the interface between the solid-gas phase for increased oxygen transport while simultaneously ensuring homogeneous flow of the individual volume elements. This should be achieved in terms of design and process technology in such a way that a cost-effective device implementation is ensured, which is also suitable not only for large-scale plants but also for pilot operations in the laboratory and on a smaller scale.

[0012] Furthermore, it is an additional object of the present invention to provide a replica version that is easy to install for an existing system with a rotating drum template. With regard to the requirement of the present invention to create a retrofittable device, it is considered an additional object that this ideally even enables retrofitting in systems from all manufacturers, so that the greatest possible compatibility with different designs is also required through a flexible design. The object is achieved by a device according to the independent claim. The dependent claims relate to advantageous embodiments of the device.

[0013] The object is thus achieved by a device for introducing atmospheric oxygen into a moist solid, preferably partially dewatered liquid manure. In particular, the device can be used to produce bedding for cattle, preferably for dairy farms, from the resulting liquid manure.

[0014] The device comprises at least the following components: (i) a rotatable drum, (ii) an inlet device, (iii) a discharge device, and (iv) an aeration device. The axis of rotation of the drum is aligned approximately horizontally and runs through both ends of the drum. Preferably, the axis of rotation is set at a slight angle to the axis of gravity so that, for example, excess moisture from the solid or a cleaning agent can easily flow away during batch changes.

[0015] The solids are conveyed through the drum from one end with the feed device to the other end with the discharge device. This is preferably, but not limited to, continuous; thus, both quasi-continuous and batch operations are conceivable. The solids are conveyed in the drum by rotating the drum in conjunction with a height gradient, which is adjusted during operation according to a difference in the fill levels at the drum inlet and outlet, i.e. from one end with the feed device to the other end with the discharge device. Sometimes, even a slight height gradient, depending on the fill levels at the drum inlet and outlet, is sufficient to adequately convey the solids. Conveyor screws or flap systems are preferred as the feed device.The discharge device is preferably designed as an outlet according to the principle of an overflow weir.

[0016] The aeration device uses atmospheric oxygen, which can be transported to the aeration device, for example, via conventional fans. The aeration device according to the invention for introducing atmospheric oxygen into the solid material essentially comprises at least two corresponding components, one stationary and the other rotating, located essentially outside the drum shell: Firstly, a fixed outer supply air duct which is arranged on the frame of the drum; this duct encloses a rotatably rotating outer surface of the drum with a form fit, essentially transverse to the axis of rotation of the drum and in a rotation angle segment α around the axis of rotation.

[0017] On the other hand, the outer surface of the drum is provided with at least one circumferential air inlet opening in such a way that when passing through the rotation angle segment α, the circumferential air inlet openings each come into open flow contact by overlapping with the fixed outer supply air duct.

[0018] The device according to the invention for introducing atmospheric oxygen thus aims, through this essentially two-component design of the aeration device, to ensure, in a structurally advantageous manner, ventilation from the outside into the bulk volume of moist solids present inside the drum via, ideally, several air inlets, which are ideally evenly distributed across the contact surface between the solids bulk and the drum shell. Since the ventilation air only flows from the outside to the inside when passing through the rotation angle segment α due to the overlap of the circumferential air inlets with the fixed outer supply air duct, this is determined by the rotational position of the drum itself; consequently, complex regulation and control systems can be dispensed with.This also regularly results in significant cost reductions as well as further advantages in terms of improved usability of the device under conditions of use on an agricultural farm that require robustness.

[0019] Advantageously, the supply air duct is arranged substantially below the drum and the rotation angle segment α is less than 270°, preferably less than 180°, more preferably less than 120°, and particularly preferably less than or equal to 90°. This requirement arises from the fact that, during operation, a smaller filling level of particularly preferably 50 to 70 vol.% in the drum with bulk moist solids is more appropriate than 100% filling of the empty volume, since otherwise difficult conveying would also be a disadvantage. Therefore, in large-scale operation, filling levels are typically between 40 and 80 vol.%, volume fraction of solids based on the internal empty volume of the rotating drum, whereby it has been shown that the volume fraction targeted in real operation is particularly preferably between 50 and 70%.Since it is sensible that ventilation only takes place in the rotation angle segment of the inner surface of the drum where solids actually lie against the inner surface, this is achieved structurally by the rotation angle segment α not encompassing the entire inner circumference (360°) of the drum, but only the partial rotation section seen from below, defined as rotation angle segment α; this corresponds approximately to the optimal filling level of the bulk material in the drum for a particular process with a particular moist solid to be treated.

[0020] Furthermore, it is ideally taken into account that during operation of such rotating drums, it has been shown that the surface of the solid is inclined; the angle is approximately 45° due to the flow behavior, for example in the case of a crumbly solid. Therefore, in order to make a constructive provision whereby an optimal overlap area of ​​the outer supply air duct to the circumferential air inlet openings is ensured and ventilation is carried out primarily in the area of ​​solid contact with the inner surface of the drum, it is further advantageous that a proportion α 1 of the rotation angle segment α in the direction of rotation in front of a lowest orbital point P is less than half of the rotation angle segment α, more preferably less than one third of the rotation angle segment α.

[0021] As already stated, it is an object of the present invention to ensure the largest possible exchange surface between the solid and gas phases in order to optimize oxygen transport from the gas phase into and / or to the moist solid.

[0022] Therefore, the at least one circumferential air inlet opening is advantageously provided with an air diffuser element extending, preferably radially, into the interior of the drum. This can preferably be designed as a perforated

[0023] A pipe section can be designed as an aeration candle. Alternatively, air diffuser elements can be implemented in the form of an external sieve basket, which can be filled with loose dispersion fill or fiber pellets for better air distribution into the solids.

[0024] A particularly advantageous alternative for an air diffuser element extending into the interior of the drum is an inflatable rubber ventilation hose element, as is also typically used in wastewater treatment technology. Such air diffuser elements, designed in the form of inflatable rubber ventilation hoses, are typically flanged against the air inlet opening so that when internal pressure is applied by compressed air, they inflate like a balloon against a return spring and, in this state, open small slotted openings towards the solids side. This allows air flow and oxygen transport into the adjacent solids. However, when the internal pressure is removed, these air diffuser elements relax, so that the solids on the outside of the air inlet openings do not cause contamination of the slots.

[0025] Advantageously, the air diffuser element is arranged by mechanical connection to a holder that is at least partially in contact with the outer surface of the drum, with the connection extending through the air opening. In a preferred embodiment, the holder can be a sheet metal bent in the shape of a circular arc segment. Such an arrangement ensures that the air diffuser element is mechanically stable and, above all, secured against rotation even during rotation. Furthermore, advantages arise from easy modular interchangeability of the correspondingly arranged air diffuser elements by easily loosening the respective connection.

[0026] The mechanical connection area can be located on the inside of the drum, on the outside of the drum, or even between them inside the air inlet opening. Regarding the overall design, it is advantageous if the brackets, each of which can fill a segment of a circular arc, together encompass the entire 360° of the outer circumference of the drum's lateral surface, resulting in a closed circumferential surface with a uniform radius.

[0027] In particular, it is an object of the present invention to ensure and further optimize the introduction of atmospheric oxygen into the solid, both with regard to the overall material balance of the process and the homogeneity of the history of all volume elements. This plays a particularly important role in the operation of such devices for solids colonized with thermophilic and / or aerobic microorganisms. For the preferred case in which the device according to the invention is intended for operation as a microbiological process reactor, preferably as a pasteurization and / or fermentation unit, all aspects of microbiological process engineering and their basic operations known from the prior art must be taken into account. In particular, these aspects include considerations of the residence time as well as mass and heat transfer, as well as the hydrodynamic design of the drum as a microbiological reactor.These considerations include countercurrent operation, i.e. the direction of conveyance of the solids is opposite to the direction of conveyance of the air, versus cocurrent versus crosscurrent, as well as all operation modes that can be regarded as superimposed.

[0028] Preferably, therefore, the aeration takes place in a front region of the solid volume conveyed through, which is implemented constructively in that at least a first length is defined in the direction of the axis of rotation of the drum, namely as the distance between the end face of the drum near the feed device and the position of the at least one aeration device according to the invention, and a second, total, length of the drum is defined, namely as the distance between its two mutual end faces, wherein the ratio of the first length to the second length is preferably less than or equal to 60%, more preferably less than 45%, even more preferably less than 35% and particularly preferably less than 10%.

[0029] Furthermore, it may be preferable to arrange several, for example two or three, aeration devices according to the invention at different positions, i.e., with different first lengths, along the direction of the rotational axis of the drum for the gradual introduction of air. For example, for an embodiment with two aeration devices according to the invention, it may be preferable to arrange one at a first length of 10% and the other at a first length of 70%.

[0030] Such improved aeration is primarily aimed at pasteurization applications. As has been shown in practice, a complete pasteurization result in the solids can be achieved already in the first half of the drum due to the optimized aeration. Since the temperature of the solids required for pasteurization is already reached in the front area of ​​the drum and should not rise any higher, The exothermic heat generated by the microorganisms is dissipated by the air flowing over the solid. This further achieves the intended drying of the solid. It has proven advantageous not to further alter the dry content of the solids exiting the drum, but rather to feed the drum with moister solids via the feed device. If this procedure is possible, an additional advantage arises in the case of upstream press screw separators, since processing materials with a higher moisture content can be processed with less wear.

[0031] In embodiments of the device according to the invention with multiple ventilation devices, it may further be preferable to measure the quantitative ratio of the respective supplied air volume flows via respective flow meters arranged upstream of the respective ventilation device in the respective supply air lines. Furthermore, it may be preferable to specifically adjust the respective supplied volume flows relative to one another.

[0032] A fan is preferably used to extract the air from the drum. For the purposes of the present invention, the term "fan" also encompasses compression stages up to very high compression ratios, i.e., the outlet pressure to the inlet pressure of the compressed gas phase. To convey the air into the drum interior, at least one additional fan is preferably used, which is connected to the supply air connection and thus to the ventilation device. The exhaust air and the supply air can preferably be coupled via a heat exchanger for heat recovery.

[0033] Within the scope of the invention, it was also recognized that aeration can ideally also depend on various parameters of the moist solid to be aerated; for example, such process states are characterized by typical measurement data, e.g., free and / or bound oxygen concentration, temperature, moisture content, and pH value. Further typical process parameters include the parameters that typically characterize the air flow, e.g., the external pressure and / or the pressure present within the drum, which can be adjusted, for example, according to the integral void volume of the moist agglomerate to be aerated and also from other intrinsic properties such as, for example, the structure of this void volume. In this respect, it is preferred that the device contains a further fan, namely for uniformly blowing the air into the supply air duct to the drum.Preferably, the device further comprises a control device for changing the volume flow and / or the pressure of the injected air as a function of the rotational position of the drum and / or the pressure in the drum and / or the amount of air conveyed and / or measurement data characterizing the state of the moist solid, preferably the free and / or bound oxygen concentration and / or the temperature and / or the moisture content and / or the pH value.

[0034] The invention includes the possibility of introducing other gases into the moist solid as an alternative to introducing only atmospheric oxygen.

[0035] Advantageously, the power of the exhaust fan is slightly higher than the power of the inlet fan. This maintains a slight negative pressure in the drum, ensuring the airflow from the aeration device through the solids. Furthermore, the fan must also remove the evaporated water from the drum. The control device can preferably also ensure that the positive or negative pressure inside the drum remains within a certain range.

[0036] Regardless of the fact that selected parameters of the drum operation can be incorporated into the control device for changing the volume flow and / or the pressure of the injected air, it can be conversely or additionally provided that a control device in turn influences the speed of the drum.

[0037] Within the scope of the invention, it was further recognized that the high temperature of at least 70°C required to ensure pasteurization over a longer period of time can be achieved, in particular, when optimal living conditions are created for thermophilic microorganisms. The device according to the invention provides optimal living conditions for the proliferation of aerobic thermophilic microorganisms. This is particularly important because aerobic organisms, which require oxygen for their metabolism, have a much faster proliferation rate and thus also a higher temperature generation capacity than anaerobic organisms.

[0038] Therefore, the device preferably comprises a heating device upstream of the at least one supply air duct, preferably in the region of a supply air line to the supply air duct, for directly and / or indirectly heating the blown-in air.

[0039] This can preferably be configured as a supply air / exhaust air and / or a supply air / fuel heat exchanger. Alternative and / or additional active heating devices include electric heating elements, microwaves, and / or infrared heaters.

[0040] Furthermore, a method for operating the device according to the invention is disclosed. The method comprises, as central method steps, (i) rotating a rotatably arranged cylindrical drum about a preferably horizontal axis of rotation; (ii) introducing the solid into the drum and discharging the solid from the drum, preferably to a filling level of 30 to 98% by volume, more preferably 35 to 95% by volume, even more preferably 40 to 80% by volume, particularly preferably 50 to 70% by volume; (iii) introducing atmospheric oxygen into the solid by means of at least one essentially external aeration device with an overall method efficiency characterized in that the oxygen concentration of the air is depleted from 21% upon entry into the drum via the inlet channel.

[0041] As already described, a fan (fan 12) is preferably used to extract the air from the drum. The oxygen concentration depletion is determined independently of the air drawn in via the discharge end by the fan (fan 12). Preferably, the depletion is at least 10%, preferably at least 5%, even more preferably at least 2%, particularly preferably at least 0.5%.

[0042] A preferably additional process step in the operation of the drum according to the invention is the dispersion and / or homogenization of the solid, which is intended to go beyond the dispersion and / or homogenization effect already generated in the solid by the rotation of the drum. Furthermore, the solid is preferably additionally heated in the drum, particularly if the process according to the invention involves pasteurizing the solid in the drum, preferably by keeping it at a temperature of at least 70°C for a residence time of at least one hour, i.e., in the form intended for effective sanitization.

[0043] The subclaims and the advantageous embodiments of the device according to the invention find correspondingly advantageous application for the method.

[0044] Furthermore, a product produced using a device according to the invention is disclosed; the product is in the form of a solid, preferably an agglomerated solid, a moist solid and / or a solid dried to an equilibrium residual moisture content, which is also pourable, even more preferably free-flowing; the product produced is characterized in that it is pasteurized upon leaving the plant.

[0045] Advantageously, it is characterized by the fact that for the three bacterial strains primarily used in laboratory operations and considered markers, no pathogenic bacterial counts are detectable in representative samples. Conventionally, the degree of pasteurization is considered complete when the remaining maximum bacterial count concentration is as follows: • Escherichia coli: less than 5,000 [germ count], preferably less than 1,000 [germ count] per 1 g sample, particularly preferably less than 1,000 [germ count] in 5 out of 5 1 g samples to be tested; and / or • Enterococci: less than 5,000 [germ count], preferably less than 1,000 [germ count] per 1 g sample, particularly preferably less than 1,000 [germ count] in 5 out of 5 1 g samples to be tested; and / or • Salmonella: lower 0 [germ count] per 25 g samples, particularly preferred low 0 [germ count] in 5 out of 5 25 g samples to be examined.

[0046] An embodiment of the invention is described in detail below with reference to the accompanying drawings. In the drawings: Fig. 1 a schematic representation of the device according to the invention with heat exchanger according to a first embodiment; Fig. 2 a cross-sectional view of the drum of the device according to the invention with internal solid according to all embodiments; Fig. 2a a detail of the lower part of the cross-sectional view from Fig. 2; Fig. 3 an isometric overall view of the device according to the invention according to all embodiments, shown as a section of the cylindrical outer surface of the drum along its axis of rotation. The following are, in the sense of exploded views, individual components of the device according to the invention according to all embodiments or their various states in the assembly progress to form assemblies: Fig. 3a an isometric view of the ventilation device according to the invention according to all embodiments as such without a drum; Fig. 3b corresponding to Fig. 3a, a section along the direction of rotation of the drum from its outer surface as an element of the device according to the invention according to all embodiments; Fig. 3c an isometric view of the section of the outer surface of the drum of the device according to the invention according to all embodiments, fully assembled with holders in which respective air diffuser elements are held towards the drum interior; Fig. 3d isometric view as a detail of the Fig. 3c shown mounted bracket with air diffuser element; Fig. 3e is an isometric view of a preferred air diffuser element according to all embodiments; Fig. 3f is an isometric view of a preferred wear ring of the device according to the invention according to all embodiments; to be provided between the Fig. 3a and the external ventilation device shown in Fig. 3c shows the pre-assembled shell surface with air diffuser elements; Fig. 4 a schematic representation of the device according to the invention with two ventilation devices according to a second embodiment.

[0047] The Fig. 1 to 3f show a first embodiment of an aeration device 15 in a device 1 and its integration into a process engineering system diagram for operating the device 1 according to the invention, specifically in this embodiment with provided heat recovery by means of a heat exchanger 25 from the exhaust air 27 sucked out of a drum 2 by means of a fan 12. By means of the device 1 according to the invention for introducing atmospheric oxygen into a moist solid, comprising the aeration device 15 as a central component, the disclosed method can be carried out and the disclosed product can be produced.

[0048] The device 1 comprises the drum 2. This drum 2 is mounted for rotation about a rotation axis 3. Several bearings are arranged to support the drum 2. These bearings support the outer surface of the drum 2 and can dampen vibrations relative to the installation surface. Furthermore, a drive (not shown) is arranged to set the drum 2 in rotation.

[0049] An inlet end face 6 and a discharge end face 7 are defined on the drum 2. An inlet device 8 is integrated into the inlet end face 6. A discharge device 9 is integrated into the discharge end face 7. The inlet device 8 serves for the preferably continuous introduction of the solid 30 into the interior of the drum 2; solid 30 is preferably continuously discharged via the discharge device 9. The inlet device 8 for the moist solid 30, shown schematically here, can be designed, for example, as a screw conveyor or funnel-shaped feed chute; preferably, a press screw separator (not shown here) can be installed directly upstream of the actual inlet device 8, from which the solid 30 to be aerated falls directly into the inlet device 8 or is conveyed by a screw conveyor.The preferably variable arrangement of the feed and discharge devices 8, 9 allows the filling level of the drum 2 with solid material 30 to be adjusted. As a preferred embodiment of the discharge device 9, in this preferred embodiment of the device according to the invention, the discharge device 9 is arranged vertically at a certain height of the discharge end 7 of the rotating drum 2 as a discharge chute 13. Due to this vertically selected arrangement of the discharge chute 13, the same proportion of solid material falls into the discharge chute 13 and thus outwards as it is fed in at the feed end 6. The adjusted height of the discharge chute 13 effectively implements an overflow principle, which directly determines the filling level in the drum 2, for example in the range of 50% to 70% filling level.

[0050] The system diagram, as shown in Fig. 1 for the preferred embodiment, also makes clear the guidance of the ventilation periphery, namely here by utilising the heat contained in the exhaust air 27 through a recovery stage, designed as a heat exchanger 25.

[0051] The latter brings the warm exhaust air 27, which is extracted from the upper gas chamber of the drum 2 by an extracting fan 12 via an exhaust air connection 23, into countercurrent contact with supply air 26, which is drawn in from the environment by another fan 24. As a result, the cooling of the exhaust air 27 causes the contained water vapor and any other entrained components to condense out in the form of a condensate 28, which is then discharged.

[0052] The air thus heated in the heat exchanger 25 is compressed by compression in the further fan 24 and blown via an air supply line 22 into the ventilation device 15 according to the invention, which is mounted on an outer surface 18 of the drum 2.

[0053] Furthermore, Fig. 1 shows the definitions of the two lengths 40 and 41: The first length 40 is measured as the running length of the attachment point of the aeration device 15 according to the invention, measured from the inlet end face 6. The second length 41 is defined as the length of the drum 2 from its inlet end face 6 to its outlet end face 7, i.e., measured as the total length.

[0054] Fig. Figure 2 shows a cross-section of the drum 2 with the bulk of moist solid 30 present within it. The direction of rotation of the drum 2 is indicated by an arrow (clockwise). It is clearly visible that the solid 30, which is present at a filling level of approximately 70% of the empty drum volume, is scooped up by the rotational movement in the direction of rotation to a surface inclined at approximately 45° and then falls downwards again due to gravity in the direction of rotation, resulting in internal mixing. This illustration shows the structure of the aeration device 15 of the device according to the invention, which basically comprises at least two components, according to the exemplary embodiment shown here: A first central assembly relates to the outwardly facing part of the ventilation device 15 of the embodiment according to the invention and is designed to be stationary. This outwardly facing part of the ventilation device 15 comprises an outer supply air duct 16, through which the air containing the oxygen to be introduced into the solid 30 is blown in. This outer supply air duct 16 surrounds the outer surface 18 of the drum 2 in a form-fitting manner, visible here below the drum 2 in a rotation angle segment α as the lower circumferential component. In this exemplary embodiment, the outer supply air duct 16 is supplied with compressed air from the horizontal, tangentially flanged supply air line 22. Complementary to the rotation angle segment α relative to the circumference of the drum 2, i.e. Arranged in the upper region of the drum 2 as the upper peripheral component, a fixed sliding ring 31 positively surrounds the outer surface 18 of the drum 2. Both fixed, outwardly facing, positively locking peripheral components, i.e., on the one hand, the outer supply air duct 16 at the bottom and, on the other hand, the fixed sliding ring 31, are connected to one another in the areas of the flanges 33 and 34 provided on both sides, preferably in a force-locking and / or detachable design.

[0055] Another central component concerns the inner part of the aeration device 15 of the embodiment according to the invention, which is designed to rotate with the rotation of the drum 2. This inner part of the aeration device 15 comprises at least one air inlet opening 19 penetrating the outer surface 18 of the drum 2 and serves to continue the flow and introduce the atmospheric oxygen into the solid 30 present inside the drum 2.

[0056] Furthermore, as an intermediate element between these two central assemblies, i.e., the fixed outer-facing assembly and the rotating inner-facing assembly, a fixed rotating wear ring 32 can preferably be provided—as shown for this embodiment—to rest against the inside of the fixed outer-facing assembly, i.e., here, against the fixed sliding ring 31 and the outer air supply duct 16, and to protect them against abrasion by the rotating rotating parts. If such an intermediate element is present, as in this embodiment, it must be designed to be open across the entire area of ​​the outer air supply duct 16 to allow air to flow through to the rotating air inlet openings 19.

[0057] Clearly visible are the preferably provided air diffuser elements 20, which are intended to introduce the air from the air inlet openings 19 into the solid 30 in an improved manner. Here, they are designed as a perforated pipe section, forming an aeration candle. Four of these are arranged around the inner circumference of the drum 2, at the 12, 3, 6, and 9 o'clock positions, respectively, in the rotational position of the drum 2 shown here.

[0058] In the enlarged detail of the lower part of the drum 2 with external supply air duct 16 in detail of the Fig. 2a, the functional principle of the ventilation device 15 of the device 1 according to the invention in this embodiment is particularly clearly visible. Only the air diffuser element 20 located in the rotation angle segment α, here 90°, shown here in the rotation position at 6 o'clock, receives compressed air from the outer supply air duct 16 through the air inlet opening 19 released in this rotation position. In contrast, the other three

[0059] Air diffuser elements 20 (here in the rotational positions at 12 o'clock, 3 o'clock, 9 o'clock) are closed against air ingress in this remaining orbital angle range by the fixed sliding ring 31.

[0060] Out of Fig. The advantageous functional principle is also clearly visible in Figure 2a: As soon as the air diffuser element 20, which is located just below and through which air flows, continues to rotate clockwise until it leaves the rotation angle range α of the outer supply air duct 16, the air inlet opening 19, which is still completely free here, is increasingly blocked airtight by the fixed sliding ring 31. Fig. Figure 2 shows for the embodiment that the aeration area of ​​the solid 30 present in the drum 2, defined as the rotation angle segment α, is adapted to the surface level of the moist solid 30, which is inclined to the horizontal. This is achieved by the proportion α 1 of the rotation angle segment α in the direction of rotation before the lowest orbital point P in the embodiment shown here corresponds to a third of α, namely here: 30°.

[0061] In the areas of the two flanges 33 and 34, the cross-section of the detail according to Fig. 2a clearly shows that the connection of the outer supply air duct 16 located below with the stationary sliding ring 31 takes place there, in such a way that the cylindrical drum peripheral surface is thereby positively enclosed. It can be seen that typical flange connections can be selected, indicated here as a screw connection via at least one typically push-through opening.

[0062] Furthermore, the innermost circumferential surface is shown as the circumferential outer surface 18 of the drum 2, with which the at least one air inlet opening 19, here four, rotates. The stationary sliding ring 31 with the outer air supply duct 16 and the circumferential outer surface 18 are made of metal, preferably V4A stainless steel. In between, the stationary wear ring 32 is shown, preferably in this embodiment made of polymeric wear material with sliding properties, for example PE and / or Teflon, and / or another preferably extrudable polymer, which prevents seizure of the movable outer surface 18 in the stationary sliding ring 31. Accordingly, the material of the wear ring 32 can ideally, but not necessarily, be made of a material with such good sliding properties that it does not wear away, but is characterized by a long service life.

[0063] This fixed wear ring 32 made of polymeric material is, as can be seen from Fig. 3f in the individual representation of this component, is provided with elongated ventilation slots 36. The overlap area of ​​the rectangular elongated ventilation slots 36 with narrow support webs in between for static improvement corresponds together to the rotation angle segment α of the outer supply air duct 16. In order to prevent the visible ventilation slots 36 of the fixed wear ring 32 from rotating out of the opening of the outer supply air duct 16 in the rotation angle segment α during rotation of the drum, as shown in detail in Fig. 2a bottom right, an anti-rotation device for the fixed wear ring 32 is designed in the form of an outwardly projecting radial clamping area 35. For this purpose, Fig. 3f and Fig. 2a clearly shows that, in the embodiment shown here, this is achieved by an incision in the fixed wear ring 32 at this point, so that the radial clamping area is bent outwards in the form of a tab into the front flange 34. In this embodiment, it is shown by way of example that the radial clamping area 35 is secured by two small retaining screws, namely between two likewise radially bent end areas of the outer supply air duct 16 arranged below and the fixed sliding ring 31 arranged from above in the area in the direction of rotation of the front flange 34.

[0064] Fig. 3, 3a to 3f show the overall view of the embodiment in isometric perspective in Fig. 3 of a fully assembled ventilation device 15, wherein a section of the cylindrical outer surface 18 of the drum 2 is shown along the axis of rotation 3, namely the area in which the ventilation device 15 according to the invention is mounted. On the other hand, the individual representations of the Fig. 3a to 3f show the isometric views and enlarged detail sections in the form of an exploded view ( Fig. 3d and Fig. 3e) of the individual components.

[0065] The dimensions of such components mentioned here are to be understood as examples; they are not intended to limit the disclosure content of the invention in any way. In particular, reference is again made to the advantage of the present invention that it can be implemented in a virtually arbitrary manner across multiple dimensions.

[0066] The four air diffuser elements 20 are inserted into the outer surface 18 of the drum 2 from the outside via the four corresponding air inlet openings 19 at a 90° angle to each other. The design of the air diffuser elements 20 is shown in detail together with their holder 21 in the Fig. 3d and from the Fig. 3e. The air diffuser elements 20 shown for this embodiment are designed in the form of bar screens with an exemplary diameter of 80 mm; these diffuse escaping air bubbles along an exemplary extension depth of 160 mm into the drum interior, the latter corresponding to the height of the cylindrically shaped air diffuser elements 20. Using screen bars of the designation standard "120" and "C20" support struts results in a distribution of approximately 173 screen bars along the circumference with a diameter of 80 mm.The close-meshed sieve design, on the one hand, supports the dispersal of the incoming air into the finest bubbles against the applied Laplace bubble pressure; on the other hand, it provides protection against the escape of the solid 30, which is often present in agglomerated form, in the form of particles into the fitting gap between the circumferential outer surface 18 and the fixed wear ring 32 provided in this embodiment; because such particle escape would be a so-called "sand grain fit" and must be avoided at all costs. For a diameter of the drum 2 of 2000 mm chosen as an example and representative in this embodiment, the corresponding thicknesses of the fixed slide ring 31 and the fixed wear ring 32 would be selected to be 5 mm each, for example. As can be seen from the overall view in . Fig. 3, in this embodiment the fixed sliding ring 31 is tightly clamped around the outer surface 18 of the drum 2 by means of a clamping element 29 with adjusting screws; this serves to increase the mechanical stability for an ideally centric rotation behavior of the drum in the ventilation device 15.

[0067] Fig. Figure 3a shows, in an isometric perspective, only the fixed sliding ring 31 flanged to the corresponding outer supply air duct 16. This illustration clearly shows that the outer supply air duct 16 is spanned internally over the rotation angle segment α by a ventilation opening 37, here designed in the form of a rectangular longitudinal slot, which virtually fills it; thus, the ventilation opening 37 of the outer supply air duct 16 corresponds to the rectangular elongated ventilation slots 36 of the fixed wear ring 32.

[0068] From the Fig. 3b, which represents the section of the outer surface 18 of the drum 2 intended for assembly, shows the positioning of the four circumferential air inlet openings 19, each offset by 90°. These are shown in this

[0069] The design is also selected to have a diameter of approximately 80 mm, corresponding to the diameter of the air diffuser elements 20 to be used. Furthermore, small side stops 38 are arranged in pairs between them. These are intended as an assembly aid and for lateral fixation, on the one hand for the holders 21 for the air diffuser elements 20 (see Fig. 3c), and the other for the surrounding fixed sliding ring 31 (see Fig. 3 and Fig. 3c).

[0070] Fig. 3c corresponds to Fig. 3b shows the progress of the assembly of the ventilation device 15 by inserting the four air diffuser elements 20 through the air inlet openings 19. These air diffuser elements 20 are fixed from the outside by the brackets 21, here four, which are located on the outer surface 18 of the drum 2. As can be seen particularly well from the detail in Fig. As can be seen in Figure 3d, these four brackets 21 are bent as flat webs in the form of a circular arc segment, specifically in this embodiment at 90° each and thus completely spanning the drum diameter. This embodiment of the bracket 21 has the advantages of being easy to install by fastening from the outside, so that no screwing is required from the inside. Furthermore, this embodiment has the advantage that any disruptive screw edges or protruding screw heads are eliminated on the circumferential wear surface.

[0071] Fig. 4 shows a second embodiment of the device 1 according to the invention in a preferred modification of the device 1 according to the first embodiment, namely here with two aeration devices 15a, 15b, and their integration into a process engineering system diagram for operating the device 1 according to the invention.

[0072] The two ventilation devices 15a, 15b in different positions, i.e. at two different first lengths 40a, 40b, along the direction of the axis of rotation of the drum 2 serve to gradually introduce air. Fig.In the second preferred embodiment illustrated in Figure 4, on the one hand, the upstream ventilation device 15a is arranged at a first length 40a of approximately 30% of the length 41, and on the other hand, the downstream ventilation device 15b is arranged at a first length 40b of approximately 70% of the length 41. Volume flows of air are supplied to the two ventilation devices 15a, 15b via the respective supply air lines 22a, 22b, which in turn are detected in the supply air lines 22a, 22b by respectively arranged flow meters 42a, 42b.

[0073] In addition to the above written description of the invention, reference is hereby explicitly made to the drawings of the invention in all figures for the purpose of supplementing its disclosure. List of reference symbols 1 device 2 drums 3 axis of rotation 6 Entry front side 7 Discharge front side 8 Entry device 9 Discharge device 12 fans to extract air from the drum 13 discharge chute 15, 15a, 15b Ventilation device 16 external supply air duct 18 outer surface 19 circumferential air inlet opening 20 Air diffuser element 21 Bracket 22, 22a, 22b supply air duct 23 Exhaust air connection 24 fans for blowing air into the external supply air duct 25 heat exchangers 26 Supply air 27 Exhaust air 28 Condensate 29 clamping element 30 moist solid 31 fixed sliding ring 32 fixed wear ring 33 rear flange 34 front flange with wear ring clamp 35 radial clamping range 36 ventilation slots 37 Ventilation opening 38 page boundaries 40, 40a, 40b first pitch 41 second length 42a, 42b flow meters α rotation angle segment α 1 Share of the rotation angle segment P lowest orbit point

Claims

[1] Device (1) for introducing atmospheric oxygen into a moist solid (30) comprising - a cylindrical drum (2) arranged to rotate about an axis of rotation (3), - an inlet device (8) on the drum (2) for introducing the solid (30), - a discharge device (9) on the drum (2) for discharging the solid (30), - at least one aeration device (15) for introducing atmospheric oxygen into the solid (30), characterized by that the ventilation device (15) comprises: - a fixed outer supply air duct (16) arranged on the drum (2), wherein the fixed outer supply air duct (16) surrounds a rotatably encircling outer surface (18) of the drum (2) transversely to the rotation axis (3) and in a rotation angle segment (α) around the rotation axis (3) with a form fit, and - at least one air inlet opening (19) which rotates with the rotation of the drum (2) through the outer surface (18) of the drum (2), so that when passing through the rotation angle segment (α) the at least one circumferential air inlet opening (19) comes into open flow contact with the fixed outer supply air duct (16) by overlapping. [2] Device according to claim 1, characterized by that the outer supply air duct (16) is arranged below the drum (2) and the rotation angle segment (α) is less than 270°, wherein a portion (α 1 ) of the rotation angle segment (α) in the direction of rotation before a lowest orbital point (P) is less than half of the rotation angle segment (α). [3] Device according to claim 1 or 2, characterized by that the at least one circumferential air inlet opening (19) is provided with an air diffuser element (20) extending into the interior of the drum (2). [4] Device according to claim 3, characterized bythat the air diffuser element (20) is arranged by mechanical connection to a holder (21) which at least partially rests on the outer circumferential surface (18) of the drum (2), the connection running through the air inlet opening (19). [5] Device according to one of the preceding claims, characterized by , that • at least a first length (40) in the direction of the axis of rotation (3) of the drum (2) is defined between the front side (6) of the drum (2) near the feed device (8) and the position of the at least one aeration device (15), • a second, total length (41) of the drum (2) is defined between its two mutual end faces (6) and (7), wherein the ratio of the first length (40) to the second length (41) is less than or equal to 60%. [6] Device according to one of the preceding claims, characterized bya fan (24) for blowing air into the outer supply air duct (16) to the drum (2), comprising a control device for varying the volume flow and / or the pressure of the blown-in air as a function of: • the rotational position of the drum (2); and / or • the pressure in the drum (2); and / or • the air volume conveyed; and / or • measurement data characterizing the state of the solid (30). [7] Device according to one of the preceding claims, characterized by a heating device connected upstream of the at least one external supply air duct (16) for the direct and / or indirect heating of air to be introduced, comprising: • a heat exchanger (25) for transferring heat from air extracted from the drum (2) by a fan (12) to the air to be introduced; and / or • an electric heating element and / or a fuel heater and / or a microwave heater and / or an infrared heater. [8] Device according to claim 7, characterized by that the extracted air is dried in the heat exchanger (25) while removing a moisture condensate (28).

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