Dryer system
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-05-10
- Publication Date
- 2026-03-18
AI Technical Summary
Existing dryer systems face challenges in meeting stringent dust emission limits due to the high volume of exhaust air, leading to high manufacturing and operating costs, as they require large and complex filter systems to handle the high volume flow of gas and particles.
The dryer system employs a gas-particle separator with a fan that divides the gas flow into a low-particle main flow and a particle-rich secondary flow, where only the secondary flow is filtered, allowing for a smaller filter system and reduced energy consumption.
This approach enables the release of purified exhaust air while minimizing environmental impact and operational costs by separating particles effectively and reducing the volume of gas that needs to be filtered, thus meeting legal emission limits in a cost-effective and energy-saving manner.
Smart Images
Figure EP2024062908_21112024_PF_FP_ABST
Abstract
Description
[0001] Dryer system
[0002] The invention relates to a drying system comprising a dryer for products to be dried, at least one gas inlet connected to the dryer, at least one gas outlet connected to the dryer, wherein the dryer has a receiving device designed to receive the products to be dried between the at least one gas inlet and the at least one gas outlet, and at least one gas extraction device connected to the at least one gas outlet for extracting gas and particles of the products entrained by the gas.
[0003] The invention also relates to a method for drying products, comprising the steps:
[0004] - Placing the products in a dryer;
[0005] - Exposing the products to a gas flow in the dryer;
[0006] - removing the gas which has come into contact with the products and particles of the products entrained by the gas from the dryer by means of at least one gas extraction device.
[0007] Dryer systems for drying products, for example agricultural products, using an air stream or generally a gas stream and, if appropriate, by adding heat are known. For this purpose, in known systems, ambient air in an upper area of the dryer system is passed over heating devices and is thereby heated. The products are applied as evenly as possible to a drying belt running beneath the heating devices, for example made of an air-permeable, woven plastic material. The process air, heated by the heating devices, is then sucked downwards through the drying belt and in the process removes moisture from the products on the belt. The moisture-laden exhaust air is released back into the environment. In known dryer systems, the products to be dried also act as filters.In the past, this filter effect was sufficient for many products to comply with legal requirements for dust emissions. However, since the type of materials to be dried has changed over time and more and more waste wood is being added, which is relatively dry and has a higher dust content than, for example, wood chips, compliance with the emission limits is becoming increasingly difficult. One option for complying with the emission limits is to filter the exhaust air stream. The disadvantage of this is that the filter required for this generally processes very large air volumes, usually up to 350,000 m. 3 / h. Conventional dryer systems that require filtering of the exhaust air stream therefore result in high manufacturing and operating costs.
[0008] Devices for separating particles from air flows without a filter are also known.
[0009] GB 187,348 A discloses a fan with a housing and a rotor. The housing contains several openings leading into pockets. Due to the rotation of the rotor, which draws in air in an axial direction, particles to be separated from the air are drawn to an inner wall of the housing and then carried by the airflow into the pockets, where they are collected.
[0010] US 3,796,511 A discloses a fan with a partially circular housing in which a rotor draws in air and sets it in rotation. Particles entrained in the air are directed by centrifugal force to the inside of the housing and exit through a slot in the housing.
[0011] US Pat. No. 8,353,665 B1 relates to a fan for use in a dual-chamber dirt extraction blower, with a first outlet for cleaned air and a second outlet for dirt and air. The fan has specially shaped blades. The dirt extraction blower has a complex design.
[0012] However, the known devices for separating particles from air flows are not designed to clean an exhaust air flow from a drying system while complying with legally defined emission limits.
[0013] The object of the invention is to create a drying system and a method for drying products of the type mentioned above, which avoid or at least mitigate the disadvantages known from the prior art. The drying system should only release purified exhaust air into the environment and yet be cost-effective to construct and operate in an energy-efficient manner. The method should enable reliable and cost-effective drying of products with the lowest possible environmental impact from released dust or particles in general.
[0014] For this purpose, the invention provides a drying system as defined in claim 1 and a method for drying products as defined in claim 12. Advantageous embodiments and further developments are specified in the dependent claims.
[0015] With regard to the dryer system, the invention provides that at least one of the at least one gas extraction device has a gas particle separator with a fan for generating a gas flow, wherein the fan is arranged in a flow path running from the gas inlet via the gas outlet and through the gas particle separator, wherein in an operating state of the gas extraction device, the flow path in the gas particle separator has a first flow path, in particular main flow path, and a second flow path, in particular secondary flow path, such that a smaller mass flow of particles is provided in the first flow path than in the second flow path, wherein the gas extraction device has a first outlet, in particular main outlet, into which the first flow path opens, and a second outlet, in particular secondary outlet, into which the second flow path opens,the second output is connected to a filter system.,
[0016] The drying system therefore has a dryer in which products to be dried can be dried. Examples of the products to be dried are cuttings, biomass or biowaste, in particular wood shavings, wood chips, bark, sugar beet pulp, alfalfa, grass, bagasse, corn, biomass as fuel, pomace, corn germlings or brewer's spent grains. For drying, the products are exposed to a gas stream which removes moisture from the products. The gas stream preferably has a higher temperature than room temperature or ambient temperature, for which purpose at least one heating device can be arranged in front of the dryer or in the dryer. In order to guide the gas stream through the dryer, at least one gas inlet connected to the dryer and at least one gas outlet connected to the dryer are provided.The gas stream can be introduced into the dryer via the gas inlet and the gas stream can be discharged from the dryer via the gas outlet. Between the at least one gas inlet and the at least one gas outlet, in particular in the area for the gas stream, there is a receiving device which is designed to receive the products to be dried. For example, the receiving device has a carrier belt made of an air-permeable material, in particular woven plastic material, onto which the products can be placed. During the drying process, the products picked up by the receiving device not only give up moisture into the gas stream flowing around the products, but as the drying process progresses, small particles, for example dust particles, small plant residues or the like, are released from the products and carried along with the gas stream.The gas stream therefore has a higher humidity and a higher concentration of particles at the gas outlet than at the gas inlet. In order to extract the gas and the product particles entrained with the gas from the dryer, at least one gas extraction device is connected to the at least one gas outlet. The gas extraction device thus extracts the gas and the entrained particles from the dryer in an operating state. The at least one gas extraction device can also be provided to extract the gas stream through the gas inlet into the dryer. If a plurality of gas outlets are provided, each gas outlet is preferably connected to its own gas extraction device. However, a plurality of gas outlets can also be connected to a common gas extraction device.If, in contrast to the present invention, an attempt were made to filter the entire extracted gas with the particles it contains using a filter, this would be due to the high volume flow of the gas, for example 350,000 m. 3 / h, a comparatively complex filter system is required. In addition, the gas extraction device would have to be dimensioned with a correspondingly high electrical output in order to convey the entire volume flow through the filter system, which would result in high operating costs. In contrast, according to the invention, a separation of the extracted gas flow with the particles contained therein into a low-particle gas flow, preferably with a high volume flow, and a particle-rich gas flow, preferably with a lower volume flow, is provided, with only the particle-rich gas flow, preferably with a lower volume flow, being filtered. For this purpose, it is provided that at least one of the at least one gas extraction device has a gas-particle separator with a fan for generating a gas flow. The gas-particle separator is designed, as is generally customary, to remove particles from the gas flow.For this purpose, the gas-particle separator has a fan to generate a gas flow, which fan sucks in the gas with the particles during operation. The fan is arranged in a flow path running from the gas inlet via the gas outlet and through the gas-particle separator. When the gas extraction device is in operation, the flow path in the gas-particle separator has a first flow path, in particular a main flow path, and a second flow path, in particular a secondary flow path, such that a smaller mass flow of particles is provided in the first flow path than in the second flow path. In other words, a smaller mass flow of particles is conveyed via the first flow path and a larger mass flow of particles is conveyed via the second flow path. The first flow path can be a main flow path and the second flow path can be a secondary flow path.In this case, a larger volume flow of gas and a smaller mass flow of particles are provided in the main flow path than in the secondary flow path. Accordingly, a larger volume flow of gas and a smaller mass flow of particles can be conveyed via the main flow path, and a smaller volume flow of gas and a larger mass flow of particles can be conveyed via the secondary flow path. The gas flow is thus divided in the gas-particle separator into a first flow in the first flow path and a second flow in the second flow path. In order to discharge the divided gas flow from the gas extraction device, the gas extraction device has a first outlet, in particular a main outlet, into which the first flow path, in particular the main flow path, opens, and it has a second outlet, in particular a secondary outlet, into which the second flow path, in particular the secondary flow path, opens.Since the first flow contains fewer particles, it does not need to be filtered. The second outlet, however, is connected to a filter system. The filter system is designed to filter the particles contained in the second flow path out of the gas flow so that a purified gas can be released into the environment which, in particular, meets the legal limits for emissions. Since only the second flow is filtered at a smaller volume flow of gas than the overall gas flow, the filter system can be correspondingly small and operated in an energy-efficient manner. The volume flow of the gas in the first flow path can be greater than, equal to, or smaller than the volume flow of the gas in the second flow path.If the first flow path is a main flow path and the second flow path is a secondary flow path, the ratio of the volume flow of the gas in the main flow path to the volume flow of the gas in the secondary flow path can be, for example, between 90:10 and 70:30, preferably approximately 80:20. For example, the volume flow of the gas in the second flow path, in particular the secondary flow path, can be 30,000 m³. 3 / h up to 70000 m 3 / h. The ratio of the mass flow of the particles in the second flow path, in particular if this is a secondary flow path, to the mass flow of the particles in the first flow path, in particular if this is a main flow path, can be, for example, between 90:10 and 70:30, preferably about 80:20. For example, the particle concentration at the gas outlet can be 50 mg / m 3 the volume flow of the gas at the gas outlet 350000m 3 / h, the proportion of particles in the second flow path is 80% of the total particles and therefore the mass flow of particles in the second flow path is 14 kg / h (with the range examples given above, approximately 12 kg / h to 16 kg / h). After the filter system, the particle concentration can be 0.1 mg / m 3 and the mass flow of the particles is between 3 and 10 g / h, for example 7 g / h. For a different volume flow of the gas at the gas outlet, for example 10000 m 3 / h, of course, different values result.
[0017] When reference is made in this description to location and direction specifications such as "top," "bottom," "front," "rear," or "side," these specifications are to be understood in a state in which the dryer system was erected and ready for operation. The term "vertical" means in the direction of gravity, from "top" to "bottom," or vice versa.
[0018] According to a preferred embodiment of the dryer system, the first outlet and the second outlet can be provided in a tubular connecting body connected to a separator outlet of the gas particle separator. In this way, it is not necessary to modify an existing, comparatively expensive gas particle separator in order to incorporate the first outlet and / or the second outlet therein, or to convert an existing fan to a gas particle separator with a first and second outlet. Instead, the first outlet and the second outlet can be implemented in the tubular connecting body at the factory or subsequently incorporated into the connecting body at the place of use. The connecting body can be produced comparatively inexpensively and, when the dryer system is assembled, is connected to the gas particle separator, in particular arranged at the separator outlet of the gas particle separator.In order to be able to discharge the second flow as completely as possible through the second outlet from the gas-particle separator, the second outlet is preferably arranged as close as possible to the separator outlet. It is particularly advantageous if the distance of the second outlet from the separator outlet is less than the largest cross-sectional dimension of the separator outlet, in particular at most half the largest cross-sectional dimension of the separator outlet. The tubular connecting body can be round or polygonal in cross-section, in particular circular, rectangular or square, and have a length which is greater than, equal to or less than the largest cross-sectional dimension of the separator outlet.
[0019] For a particularly simple design, it can be provided that the second outlet is a through-opening in a circumferential jacket surface of the connecting body. The through-opening can be produced in the jacket surface using inexpensive tools, such as a drilling device, a cutting tool or a punching device. It is particularly advantageous if the filter system has a particle filter and a filter fan assigned to the particle filter, wherein in particular the particle filter and the filter fan are arranged in a common filter flow path. In this case, the particle filter is designed to retain particles of different sizes which are fed to the particle filter, i.e. to prevent them from passing through.In order to enable sufficient gas flow through the particle filter, a filter fan can also be provided, which can be arranged upstream or downstream of the particle filter in the direction of flow of the gas flow. The filter fan generates in particular a suitable pressure of the second flow on the particle filter. The value of the pressure depends on the properties, for example the density and the thickness of the particle filter in the direction of flow. In order to ensure that the second flow can be completely filtered, the particle filter and the filter fan are arranged in particular in a common filter flow path, i.e. a common flow path in the filter system.
[0020] If at least two gas extraction systems with gas particle separators are provided, the same number of filter systems as gas extraction systems with gas particle separators can be provided, and the second outlet of each of the at least two gas extraction systems with gas particle separators can be connected to a filter system assigned only to this second outlet. In this way, each second outlet can be connected to its own filter system, allowing the filter systems to be designed smaller.
[0021] However, it can be particularly expedient for the second outlets of at least two gas extraction devices with gas particle separators, in particular of all gas extraction devices with gas particle separators, to be connected to a common filter system. In this case, the filter system common to several second outlets is dimensioned to filter several second streams together. For example, at least two second outlets can be connected to a common filter system and other second outlets can each be connected to their own filter system. For a cost-effective design, it can be provided that the particle filter is a bag filter or a cartridge filter. A bag filter is essentially a surface filter generally made of fiber material, wherein the filter medium is shaped into a bag.A cartridge filter generally has the shape of a cylindrical sleeve and filters the secondary stream using the sleeve's outer surface. Thus, known particle filters can be used.
[0022] It can be particularly advantageous if a first fluid line for returning gas and particles from the first flow path to the gas inlet is provided between the first outlet of at least one of the gas extraction devices and at least one of the at least one gas inlet, and / or if a filter fluid line for returning gas and any remaining particles from the second flow path to the gas inlet is provided between a filter outlet of the filter system and at least one of the at least one gas inlet. By returning the at least one first flow and / or the at least one second flow filtered by the filter system to the dryer, the filtering process can be repeated and thus carried out even more effectively.If, in addition, the temperature of the gas stream in the dryer is increased above room or ambient temperature by means of a heating device, the recirculated first stream and / or the recirculated filtered second stream preferably also have a temperature above room or ambient temperature, thereby assisting the heating device and allowing the drying of the products to be particularly energy-efficient. For this purpose, the first fluid line and / or the filter fluid line can be thermally insulated. Alternatively, at least part of the heat of the first stream and / or the filtered second stream can be provided to the dryer via a heat exchanger.
[0023] In order to separate the particles even more precisely from the gas in the gas particle separator and to keep them in the second flow path, the fan can be a radial fan with a fan housing and an impeller arranged therein. In particular, the fan housing can be provided with a separation ring arranged around a rotational axis of the impeller and protruding from an inner side of the fan housing. The separation ring helps guide the particles in the second flow path after they have been sucked into the second flow path by the impeller and helps to prevent the particles from undesirably falling back into the first flow path. The separation ring can be designed as a bent flat iron. For example, the separation ring can be arranged in a plane perpendicular to the rotational axis of the impeller.As is known, a radial fan sucks a gas into the fan housing in the direction of the axis of rotation of the impeller, deflects the gas in a radial direction of the impeller by the rotation of the impeller and blows the gas out of the fan housing again in a radial direction.
[0024] The products can be dried particularly efficiently if the dryer is a continuous dryer, in particular a belt dryer. In a continuous dryer, the products are conveyed through the dryer. Particularly preferably, the continuous dryer, in a belt dryer design, has a revolving conveyor belt on which the products can rest. Continuous dryers can also have the advantage of a low installation height.
[0025] Furthermore, it is preferred that the dryer has a plurality of drying zones, in particular a plurality of drying chambers, and preferably has a controller which is designed to set different process parameters in the drying zones, in particular different residence times of the products to be dried and / or different temperatures and / or different volume flows of the gas. The product to be dried can therefore pass through a plurality of drying zones, in particular a plurality of drying chambers, with appropriate process parameters being set in each drying zone / drying chamber. The controller can be connected to an input device, such as a keyboard, and an output device, such as a screen, for entering and / or checking the process parameters.The at least one gas inlet can be connected to at least one drying zone or drying chamber, and the at least one gas outlet can also be connected to at least one drying zone or drying chamber. For example, each drying zone or drying chamber can be connected to its own gas outlet.
[0026] The drying system can be designed to be particularly simple and environmentally friendly if the gas contains or is air.
[0027] With regard to the procedure, it is provided that:
[0028] - the gas flow along the products is generated through the gas particle separator by means of a fan of a gas particle separator of at least one of the gas extraction devices;
[0029] - the gas flow in the gas-particle separator is divided into a first flow, in particular main flow, and a second flow, in particular secondary flow, which first flow has a smaller mass flow of particles than the second flow;
[0030] - the first flow is discharged via a first outlet, in particular the main outlet, of the gas extraction device; and
[0031] - the second flow is passed via a second outlet, in particular a secondary outlet, of the gas extraction device into a filter system connected to the second outlet and is filtered in the filter system.
[0032] The method for drying products therefore provides for introducing the products into a dryer. In particular, the products to be dried can be picked up by a picking device, for example placed as evenly as possible on a drying belt. The picked up products are exposed to a gas flow in the dryer, preferably also at a temperature above room temperature or above ambient temperature. The gas flow absorbs moisture from the products, thereby drying them. The gas that comes into contact with the products and any product particles entrained by the gas are removed from the dryer by at least one gas extraction device. Before the extracted gas can be released into the environment, at least some of the particles contained in the gas must be filtered out. Which particles must be filtered out is defined at least by legal requirements.In order to avoid having to filter the entire gas flow, the gas flow is split. For this purpose, at least one of the gas extraction devices has a gas particle separator with a fan which generates the gas flow along the products and through the gas particle separator. The gas particle separator splits the gas flow in the gas particle separator into a first flow, in particular the main flow, and a second flow, in particular the secondary flow. The resulting first flow has a smaller mass flow of particles than the second flow. If the first flow is a main flow and the second flow is a secondary flow, the main flow has a larger volume flow of gas and a smaller mass flow of particles than the secondary flow. The generated first flow is discharged from the gas extraction device via a first outlet, in particular the main outlet, of the gas extraction device.The generated second flow, in particular secondary flow, is however passed via a second outlet, in particular secondary outlet, of the gas extraction device into a filter system connected to the second outlet and filtered in the filter system. Since the filter system only has to filter the second flow with a small volume flow of gas compared to the total flow, the filter system can be dimensioned accordingly small and operated in an energy-saving manner. With regard to the features of the method, reference is also made to the preceding description of the dryer system insofar as this is helpful for understanding the method and insofar as features of the method can be derived from this description of the dryer system. With regard to the features of the dryer system, reference is also made to the description of the method.
[0033] According to a preferred embodiment of the method, the first flow and the second flow are directed into a tubular connecting body which is connected to a separator outlet of the gas-particle separator and has the first outlet and the second outlet. In this way, the first flow can be directed out of the tubular connecting body of the gas extraction device through the first outlet and the second flow through the second outlet. For this purpose, the tubular connecting body is connected to a separator outlet of the gas-particle separator. The gas-particle separator or an existing fan therefore does not have to be modified in order to direct the second flow out. If the pressure of the second flow on a particle filter of the filter system is increased using a filter fan of the filter system, the particle filter can be made smaller and have a higher density.The filter fan therefore pushes or sucks the gas laden with particles through the particle filter.
[0034] If it proves advantageous to operate several smaller filter systems, it is advantageous if the second flows from all gas extraction devices with gas particle separators are directed into individual, functionally separate filter systems and filtered in the separate filter systems.
[0035] If, however, it proves to be advantageous to operate a comparatively larger filter system, it is preferred that the second flows from at least two gas extraction devices with gas particle separators, in particular from all gas extraction devices with gas particle separators, are directed into a common filter system and are filtered in the common filter system.
[0036] The invention will be further explained below using preferred, non-limiting embodiments with reference to the drawings. In the drawings:
[0037] Fig. 1 shows a drying system according to the invention with a dryer, a gas extraction device and a filter system, in a schematic representation;
[0038] Fig. 2A shows the gas extraction device with a gas particle separator, in an enlarged schematic representation, in an elevation view opposite to the direction of the gas flow into the gas particle separator;
[0039] Fig. 2B shows the gas extraction device from Fig. 2A in an elevation view perpendicular to the direction of gas flow into the gas particle separator;
[0040] Fig. 2C shows the gas extraction device from Fig. 2A in a view from above;
[0041] Fig. 3 is a schematic diagram in which each gas extraction device with gas particle separator is connected to its own filter system;
[0042] Fig. 4 is a schematic diagram in which all gas extraction devices with gas particle separators are connected to a common filter system; and
[0043] Fig. 5 is a flow diagram of the process for drying products.
[0044] Please note that the individual figures are not necessarily drawn to scale. Furthermore, parts of the drying system that are visible in other figures may be omitted from individual figures, provided that the omitted parts are not essential to the description of the individual figures.
[0045] If, for the sake of clarity, the description of the figures refers to only one component from a possible group of components, such as a single gas inlet, a single gas outlet, a single gas extraction device, a single gas-particle separator, a single filter system and / or a single first fluid line or filter fluid line, this is not necessarily to be understood as a restriction of the dryer system to just this one component. A person skilled in the art can easily understand the changes required to replace the one component with multiple components, for example to replace a gas extraction device with multiple gas extraction devices or a filter system with multiple filter systems.
[0046] Fig. 1 shows a schematic diagram of a dryer system 1, which has a dryer 2 for products P to be dried, at least one gas inlet 3 connected to the dryer 2 and at least one gas outlet 4 connected to the dryer 2. In the example according to Fig. 1, four gas inlets 3 and four gas outlets 4 are connected to the dryer 2. Gas G, in particular gas G which comprises air or is air, is admitted into the dryer 2 via the gas inlet 3. The gas G is discharged from the dryer 2 via the gas outlet 4. The dryer 2 can be a continuous dryer 2a, in particular a belt dryer 2b. Between the at least one gas inlet 3 and the at least one gas outlet 4 there is a receiving device 5, which is designed to receive the products P to be dried. In the example shown, products P to be dried are already arranged on the receiving device 5.During operation, the gas G is passed over the products P, whereby they are dried. In the example according to Fig. 1, the dryer 2 additionally has a heating device 15, in particular between the at least one gas inlet 3 and the receiving device 5, in order to heat the gas G to be passed over the products P and in this way to accelerate the drying. During the drying of the products P, the flowing gas G absorbs moisture from the products P and takes small particles, i.e. particles T, with it from the products P. The particles T are discharged from the dryer 2 together with the moisture-laden gas G via the at least one gas outlet 4. The gas flow GS in the dryer 2 is shown by arrows in Fig. 1. The dryer system 1 additionally has at least one gas extraction device 6 which is connected to the at least one gas outlet 4 and is designed to extract gas G and particles T of the products P entrained with the gas G.In the example according to Fig. 1, a single gas extraction device 6 is shown, which is connected to all gas outlets 4. The gas extraction device 6, or generally at least one of the at least one gas extraction device 6, has a gas particle separator 7 with a fan 8 for generating the gas flow GS. It is clearly visible in Fig. 1 that the fan 8 is arranged in a flow path 9 running from the gas inlet 3 via the gas outlet 4 and through the gas particle separator 7, and is shown symbolically and by dashed lines in Fig. 1.The gas particle separator 7 is designed, in an operating state of the gas extraction device 6, in particular when the fan 8 is rotating, to separate the flow path 9 in the gas particle separator 7 into a first flow path 10, which can in particular be a main flow path 10a, and a second flow path 11, which can in particular be a secondary flow path 11a, in such a way that a smaller mass flow of the particles T is provided in the first flow path 10 than in the second flow path 11 and, if appropriate, a larger volume flow of the gas G and a smaller mass flow of the particles T are provided in the main flow path 10a than in the secondary flow path 11a. In order to divert the divided gas flow GS, the gas extraction device 6 has a first outlet 12, which can be a main outlet 12a, into which first outlet 12 the first flow path 10 opens or flows.into which main outlet 12a the main flow path 10a opens, and the gas extraction device 6 has a second outlet 13, which can be a secondary outlet 13a, into which second outlet 13 the second flow path 11 opens or into which secondary outlet 13a the secondary flow path 11a opens. The second outlet 13 is connected to a filter system 14, which is designed to separate the particles T from the second flow path 11 from the gas G from the second flow path 11. The first flow HS flowing in the first flow path 10 can be released into the environment via an exhaust air opening 16, in particular a silencer 16a, of the gas extraction device 6 or can be returned to the dryer 2.
[0047] The example according to Fig. 1 further shows that the first outlet 12 and the second outlet 13 are provided in a tubular connecting body 18 connected to a separator outlet 17 of the gas-particle separator 7. In the illustration according to Fig. 1, the second outlet 13 is a through-opening 13b in a circumferential surface 19 of the connecting body 18.
[0048] The filter system 14 shown in Fig. 1 has a particle filter 20 and a filter fan 21 assigned to the particle filter 20, wherein in particular the particle filter 20 and the filter fan 21 are arranged in a common filter flow path 22 shown in dashed lines and symbolically. The particle filter 20 is designed to filter the particles T from the second flow NS flowing in the second flow path 11 and introduced into the filter system 14. In the example according to Fig. 1, the second outlet 13 is connected to the filter system 14 via a connecting fluid line 23. The filter fan 21 conveys the second flow NS to be filtered through the particle filter 20. Particles T separated out during the filtering process fall, in the example according to Fig. 1, into a collecting container 24 of the filter system 14 or below the filter system 14. The particle filter 20 can preferably be a bag filter 20a or a cartridge filter 20b.
[0049] Preferably, a first fluid line 25 for returning gas G and particles T from the first flow path 10 to the gas inlet 3 is provided between the first outlet 12 of at least one of the gas extraction devices 6 and at least one of the at least one gas inlet 3. In the example according to Fig. 1, exactly one first fluid line 25 is provided between the first outlet 12 of the gas extraction device 6 and a gas inlet 3. Additionally or alternatively, a filter fluid line 27 for returning gas G and any remaining particles T from the second flow path 11 to the gas inlet 3 can be provided between a filter outlet 26 of at least one filter system 14 and at least one of the at least one gas inlet 3. In the example according to Fig. 1, exactly one filter fluid line 27 is provided between a filter outlet 26 and exactly one gas inlet 3.
[0050] In the example according to Fig. 1, the dryer 2 is shown with a plurality of drying zones 28, in particular a plurality of drying chambers 28a. The boundaries of the drying zones 28 or drying chambers 28a are indicated by dashed lines. Furthermore, a control system 29 of the dryer 2 is shown, which is designed to set different process parameters in the drying zones 28, in particular different residence times of the products P to be dried in the dryer 2 and / or different temperatures in the dryer 2 and / or different volume flows of the gas G in the dryer 2.
[0051] Fig. 2A shows the gas extraction device 6 with the gas particle separator 7, in an enlarged schematic representation, in a rear view, i.e. opposite to the direction of the gas flow GS into the gas particle separator 7. Fig. 2B shows the gas extraction device 6 in a side view, perpendicular to the direction of the gas flow GS into the gas particle separator 7. The gas extraction device 6 clearly has, in addition to the gas particle separator 7, a tubular connecting body 18 which is connected to a separator outlet 17 of the gas particle separator 7, in particular is placed thereon, and has the first outlet 12 and the second outlet 13. Fig. 2A also shows an alternative construction in which the second outlet 13 is provided in the gas particle separator 7 itself. The differently arranged second outputs 13 are shown in dashed lines.In the example shown, the gas extraction device 6 also has an exhaust air opening 16, in particular a silencer 16a, which, however, can be omitted if the first flow HS is returned to a gas inlet 3. The gas particle separator 7 has an impeller 31 of a fan 8, which is driven by a motor 30 and is accommodated in a housing 32 of the gas particle separator 7, see in particular Fig. 2B. During operation, the rotating impeller 31 sucks the gas flow GS through a separator inlet 33 of the gas particle separator 7 into the housing 32 and sets the gas flow GS and thus also the particles T in rotation.The particles T are directed by the centrifugal force acting upon them to an inner side 34 of the housing 32 and guided along this side to the second outlet 13. They exit the gas extraction device 6 through the second outlet 13 in the inner side 34 of the housing 32 or in the outer surface 19 of the connecting body 18. The gas-particle separator 7 thus acts as a particle concentrator and centrifugal separator.
[0052] In Figures 2A, 2B and 2C, the fan 8 is shown as a radial fan 8a with a fan housing 35 and an impeller 31 arranged therein. In the example shown, the fan housing 35 is the housing 32 of the gas-particle separator 7. In the example shown, a separation ring 37 is also provided in the fan housing 35, which is arranged around an axis of rotation 36 of the impeller 31 and protrudes from the inner side 34 of the fan housing 35. The gas-particle separator 7 preferably has a front wall 38 with the separator inlet 33, a rear wall 39 opposite the front wall 38 and a circumferential, preferably at least partially round side wall 40, which connects the front wall 38 to the rear wall 39. In the example shown, the separator ring 37 projects inwards from the inner side 34 of the circumferential side wall 40.During operation of the gas-particle separator 7, the particles T sucked into the housing 32 are sucked through an annular opening 41 surrounded by the separator ring 37, pressed against the inner side 34 of the housing 32, and held in the space between the separator ring 37, the side wall 40, and the rear wall 39 until the moving particles T exit the second outlet 13. The first flow HS, on the other hand, exits the first outlet 12.
[0053] In Fig. 2C, the separator ring 37 can be partially seen through the first outlet 12.
[0054] Fig. 3 shows a schematic diagram of a dryer system 1 in which each gas extraction device 6 with gas particle separator 7 is connected to its own filter system 14. At least one of the first flows HS at the outlet of the gas particle separator 7 and / or at least one of the filtered second flows NSG at the outlet of the filter systems 14 can be returned to the dryer 2 (not shown in Fig. 3).
[0055] Fig. 4, in contrast, shows a schematic diagram of a dryer system 1 in which the second outlets 13 of at least two gas extraction devices 6 with gas particle separators 7, in the example shown of all gas extraction devices 6 with gas particle separators 7, are connected to a common filter system 14. In this case too, at least one of the first flows HS at the outlet of the gas particle separators 7 and / or the filtered second flow NSG at the outlet of the filter system 14 can be returned to the dryer 2 (not shown in Fig. 4).
[0056] Fig. 5 shows an exemplary flow diagram of the process for drying products P .
[0057] In a step S 1 , the products P to be dried are introduced into a dryer 2 .
[0058] In a step S2, the products P introduced into the dryer 2 are subjected to a gas flow GS in the dryer 2.
[0059] In a sub-step S2a, the gas flow GS along the products P is generated by a fan 8 of a gas particle separator 7 of at least one of the gas extraction devices 6.
[0060] In a step S3, the gas G brought into contact with the products P and particles T of the products P entrained with the gas G are led out of the dryer 2 by means of the at least one gas extraction device 6.
[0061] In a step S4, the gas flow GS is generated through the gas-particle separator 7 with the fan 8 of the gas-particle separator 7 of the at least one gas extraction device 6.
[0062] In a step S5, the gas flow GS in the gas-particle separator 7 is divided into a first flow HS, in particular a main flow HSa, and a second flow NS, in particular a secondary flow NSa, such that the first flow HS has a smaller mass flow of the particles T than the second flow NS or, if appropriate, the main flow HSa has a larger volume flow of the gas G and a smaller mass flow of the particles T than the secondary flow NSa.
[0063] In a step S 6 , the first flow HS / main flow HSa is discharged via a first outlet 12 / main outlet 12a of the gas extraction device 6 .
[0064] In a sub-step S 6a, the first flow HS / main flow HSa is guided into a tubular connecting body 18 connected to a separator outlet 17 of the gas-particle separator 7 and having the first outlet 12 / main outlet 12a.
[0065] In a step S7, the second flow NS / secondary flow NSa is passed via a second outlet 13 / secondary outlet 13a of the gas extraction device 6 into a filter system 14 connected to the second outlet 13 / secondary outlet 13a.
[0066] In a sub-step S7a, the second flow NS / secondary flow NSa is guided into the tubular connecting body 18 connected to the separator outlet 17 of the gas-particle separator 7 and having the second outlet 13 / secondary outlet 13a.
[0067] In a step S 8 , the second flow NS / secondary flow NSa fed into the filter system 14 is filtered in the filter system 14 .
[0068] In a sub-step S 8a, the pressure of the second flow NS / secondary flow NSa on a particle filter 20 of the filter system 14 is increased by a filter fan 21 of the filter system 14.
[0069] In a step S 9, the second flow NS / secondary flow NSa from at least one further gas extraction device 6 with gas particle separator 7, in particular from all gas extraction devices 6 with gas particle separator 7, is passed into a common filter system 14 and filtered in the common filter system 14.
Claims
Patent claims:
1. Drying system (1) comprising: a dryer (2) for products (P) to be dried, at least one gas inlet connected to the dryer (2) (3) , at least one gas outlet connected to the dryer (2) (4), wherein the dryer (2) has, between the at least one gas inlet (3) and the at least one gas outlet (4), a receiving device (5) designed to receive the products (P) to be dried, and at least one gas extraction device (6) connected to the at least one gas outlet (4) for extracting gas (G) and particles (T) of the products (P) entrained by the gas (G), characterized in that at least one of the at least one gas extraction device (6) has a gas particle separator (7) with a fan (8) for generating a gas flow (GS), wherein the fan (8) is arranged in a flow path (9) extending from the gas inlet (3) via the gas outlet (4) and through the gas particle separator (7), wherein in an operating state of the gas extraction device (6), the flow path (9) in the gas particle separator (7) has a first flow path (10), in particular Main flow path (10a), and a second flow path (11),in particular secondary flow path (11a), such that a smaller mass flow of the particles (P) is provided in the first flow path (10) than in the second flow path (11), wherein the gas extraction device (6) has a first outlet (12), in particular main outlet (12a), into which the first flow path (10) opens, and a second outlet (13), in particular secondary outlet (13a), into which the second flow path (11) opens, wherein the second outlet (13) is connected to a filter system (14).
2. Dryer system (1) according to claim 1, characterized in that the first outlet (12) and the second outlet (13) are arranged in a tubular connecting bodies (18) connected to a separator outlet (17) of the gas-particle separator (7) are provided.
3. Dryer system (1) according to claim 2, characterized in that the second outlet (13) is a through opening (13b) in a circumferential surface (19) of the connecting body (18).
4. Dryer system (1) according to one of claims 1 to 3, characterized in that the filter system (14) has a particle filter (20) and a filter fan (21) associated with the particle filter (20), wherein the particle filter (20) and the filter fan (21) are preferably arranged in a common filter flow path (22).
5. Dryer system (1) according to one of claims 1 to 4, characterized in that the second outlets (13) of at least two gas extraction devices (6) with gas particle separator (7), in particular of all gas extraction devices (6) with gas particle separator (7), are connected to a common filter system (14).
6. Dryer system (1) according to one of claims 1 to 5, characterized in that the particle filter (20) is a bag filter (20a) or a cartridge filter (20b).
7. Dryer system (1) according to one of claims 1 to 6, characterized in that between the first outlet (12) of at least one of the gas extraction devices (6) and at least one of the at least one gas inlet (3) a first fluid line (25) for returning gas (G) and particles (T) from the first flow path (10) into the gas inlet (3) is provided and / or between a filter outlet (26) of the filter system (14) and at least one of the at least one gas inlet (3) a filter fluid line (27) for returning gas (G) and any remaining particles (T) from the second flow path (11) into the gas inlet (3) is provided.
8. Dryer system (1) according to one of claims 1 to 7, characterized in that the fan (8) is a radial fan (8a) with a fan housing (35) and an impeller (31) arranged therein and, in particular, in the fan housing (35) a separator ring (37) is provided which is arranged around an axis of rotation (36) of the impeller (31) and projects from an inner side (34) of the fan housing (35).
9. Dryer system (1) according to one of claims 1 to 8, characterized in that the dryer (2) is a continuous dryer (2a), in particular a belt dryer (2b).
10. Dryer system (1) according to one of claims 1 to 9, characterized in that the dryer (2) has a plurality of drying zones (28), in particular a plurality of drying chambers (28a), and preferably has a control (29) which is used to set different process parameters in the drying zones (28), in particular different residence times of the products (P) to be dried and / or different temperatures and / or different volume flows of the gas (G) , is formed.
11. Dryer system (1) according to one of claims 1 to 10, characterized in that the gas (G) comprises air or is air.
12. A method for drying products (P) comprising the steps of: - introducing the products (P) into a dryer (2); - subjecting the products (P) to a gas flow (GS) in the dryer (2); - removing the gas (G) brought into contact with the products (P) and particles (T) of the products (P) entrained with the gas (G) from the dryer (2) by means of at least one gas extraction device (6); characterized by - generating a gas flow (GS) with a fan (8) of a gas particle separator (7) of at least one of the at least one gas extraction devices (6); - dividing the gas flow (GS) in the gas-particle separator (7) into a first flow (HS), in particular main flow (HSa), and a second flow (NS), in particular secondary flow (NSa), where- wherein the first flow (HS) has a smaller mass flow of particles (T) than the second flow (NS); - Discharge of the first flow (HS) via a first outlet (12), in particular main outlet (12a), of the gas extraction device (6); - Directing the second flow (NS) via a second outlet (13), in particular secondary outlet (13a), of the gas extraction device (6) into a filter system connected to the second outlet (13) (14) ; and - Filtering the second flow (NS) in the filter system (14).
13. Method according to claim 12, characterized in that the first flow (HS) and the second flow (NS) are introduced into a separator outlet (17) of the gas-particle separator (7) and having the first outlet (12) and the second outlet (13).
14. Method according to claim 12 or 13, characterized in that the pressure of the second flow (NS) on a particle filter (20) of the filter system (14) is increased by a filter fan (21) of the filter system (14).
15. Method according to one of claims 12 to 14, characterized in that the second flows (NS) from at least two gas extraction devices (6) with gas particle separator (7), in particular from all gas extraction devices (6) with gas particle separator (7), are passed into a common filter system (14) and are filtered in the common filter system (14).