DRYING DEVICE

Abstract: Devices for drying poultry manure, for example, are known in practice. Two or more belt conveyors (5, 8, 9, 10) with a perforated conveyor belt (5a, 8a, 9a, 10a) are arranged above one another in a drying chamber (20). The belt conveyors (5, 8, 9, 10) divide the drying chamber (20) into alternating top compartments (24) and bottom compartments (23). The bottom compartments (23) are in communication with a pressure chamber (14) via inlet openings (30), while the top compartments (24) are in communication with the environment via outlet openings (31). To ensure that, at least during operation, there is only a flow of air from a bottom compartment (23) to a top compartment (24) located directly above it in the drying chamber (20), a partition element is arranged between a bottom compartment (23) and the top compartment (24) located immediately below it. The invention is based on the insight that the partition element can be omitted from the device if a bottom compartment (23) and the top compartment (24) located immediately below it are at substantially the same pressure.

Description: Title: Drying device The invention relates to a device for drying moist material according to the preamble of claim 1. In particular, the invention relates to a device for drying manure. Such device for drying manure is known in practice, the manure to be dried being arranged in a layer on a first belt conveyor. The first belt conveyor conveys the manure through the drying chamber. At an exit end of the first belt conveyor, the manure falls onto a second belt conveyor located immediately beneath the first conveyor in the vicinity of a drive roller of the first belt conveyor. After the manure to be dried has been distributed over the belt conveyors, the belt conveyors are stopped and air is blown through the drying chamber. When there is sufficient manure present once again, the belt conveyors are set in motion again in order to receive the new supply of manure. However, the belt conveyors are in motion for no longer than the time required to receive the new supply of manure. In the known device, the bottom compartments are always in communication, via an associated inlet opening in a side wall, with an air-supply device, while the top compartments, via an associated outlet opening in the other side wall, always communicate with the environment, so that, at least during operation, in the drying chamber a flow of air is generated that, for each belt conveyor, is directed from the corresponding bottom compartment to the corresponding top compartment, i.e. from the bottom upwards, through the perforations on the conveying side of the conveyor belt. A drawback of the known device is that a partition element has to be arranged in the drying chamber beneath each bottom compartment of a belt conveyor in order to separate the corresponding bottom compartment from the top compartment of the belt conveyor located immediately below it, in order to prevent an air flow to develop from the corresponding bottom compartment, via the perforations on the return side of the conveyor belt, to the top compartment of the belt conveyor located immediately below it. A number of disadvantages and drawbacks are associated with a partition element of this nature, which is generally designed as a separating canvas or a closure plate. One drawback is that the moist material which remains hanging from the conveyor belt can stick to the partition element, resulting in the formation of a layer of dried manure on the partition element, which can only be removed with difficulty. A layer of this nature continues to build up further, having an adverse effect on the functioning of the device. Another drawback is that dust particles from material which has already been dried can fall through the perforations of the conveyor belt on the conveying side and onto the conveyor belt and the closure plate on the return side. The dust particles are carried along by the return side of the conveyor belt to an entry end of a conveyor belt . The closure plate prevents the dust particles form being able to fall through the perforations in the conveyor belt on the return side while they are being conveyed, for example through vibration of the conveyor belt, with the result that dry dust may accumulate at the entry end when the conveyor belt turns. Yet another drawback is that the inlet and outlet openings, in the vertical direction, cannot be larger than the vertical distance between the conveying side and the return side of the conveyor belt. Consequently, the accessibility of the drying chamber is highly limited, making it virtually impossible to clean the conveyor belt and/or the partition element. A further drawback of the known device is that the partition element represents a considerable cost in production of the device. A general object of the present invention is to provide a drying installation in which the abovementioned drawbacks are eliminated completely or partially or are at least reduced. A particular object of the present invention is to provide a device for drying moist material in which it is impossible for an adhering layer to form and in which it is impossible for dust to accumulate. Yet another object of the invention is to provide a device for drying moist material which can be produced at lower cost than the known device. The invention is based on the insight that the partition element in the known device is only required in order for it to be possible to maintain a sufficiently great pressure difference between the bottom compartments and the top compartments, and in particular between a bottom compartment of a belt conveyor and the top compartment of the belt conveyor in question. The invention is furthermore based on the insight that a partition element of this nature can be omitted if the device is designed in such a manner that substantially the same pressure always prevails in a bottom compartment associated with a specific belt conveyor and in the top compartment of the belt conveyor located immediately below it. According to an important aspect of the present invention, a pressure situation of this nature can be brought about in a surprisingly simple manner if a bottom compartment associated with a specific belt conveyor and the top compartment of the belt conveyor located immediately below it are both provided with either an inlet opening for the admission of air, for example supplied by the air-supply device, or an outlet opening for discharging air to, for example, the environment. In this case, the inlet openings and the outlet openings are arranged in such a manner that, at least during operation, a flow of air is formed from a bottom compartment belonging to a specific belt conveyor to the top compartment belonging to the belt conveyor in question, or vice versa. A device for drying moist material as described in the preamble of claim 1 is therefore distinguished by the fact that, at least during operation, a pressure difference prevails between the top compartment and the bottom compartment of each belt conveyor, and that a pressure in the top compartment of a belt conveyor and a pressure in the bottom compartment of the belt conveyor located immediately above it are substantially equal . With a device of this nature, it is possible to dispense with the partition element. Therefore, it is impossible for any adhering layer to be formed and dust which falls from the conveying side of the belt conveyor onto that part of the conveyor belt which lies on the return side can fall through the perforations into the compartment located below it. Advantageously, the inlet openings or outlet openings of a bottom compartment belonging to a specific belt conveyor and the top compartment of the belt conveyor located immediately below it are designed as two openings which merge into one another. In this way, the openings in question define a single opening in the side wall which is common to the compartments in question, so that the drying chamber is readily accessible. A preferred embodiment of the device according to the invention will be explained in more detail below with reference to the drawing, in which: Figure 1 diagrammatically depicts a side view of a device according to the invention with one side wall removed, Figure 2 diagrammatically depicts a cross section through a known device for drying manure, Figure 3 diagrammatically depicts a cross section through a device according to the invention. The device shown in Figure 1 is intended to dry manure, in particular poultry manure. The device comprises a drying chamber 20, which is defined by a first side wall 6 and a second side wall 7 (see Figure 2) . Four belt conveyors 5, 8, 9, 10, which extend in the horizontal direction, are arranged in the drying chamber. The first side wall 6 and the second side wall 7 are substantially parallel and are positioned vertically at a distance apart which corresponds to the width of the belt conveyors 5, 8, 9, 10. The total length of the belt conveyors 5, 8, 9, 10 is determined, inter alia, by the manure-drying capacity required. The belt conveyors 5, 8, 9, 10 are of substantially equal length and are longitudinally offset with respect to one another. The manure which is to be dried is conveyed from a manure collection point (not shown) to a holder 2 with the aid of a feed conveyor belt 1, indicated by dashed lines. By means of a metering device 3 , the manure is arranged in a layer of substantially constant thickness on the first belt conveyor 5 in the drying chamber 20. The belt conveyors 5, 8, 9, 10 are longitudinally offset with respect to one another, in such a manner that the manure which is conveyed to a downstream end of one of the belt conveyors 5, 8, 9 falls onto an entry section of the belt conveyors 8, 9, 10 located below it in the vicinity of a drive roller 11a, lib, lie of the belt conveyor 5, 8, 9 in question. With this arrangement of the belt conveyors 5, 8, 9, 10, the manure to be dried is conveyed to and fro through the drying chamber 20 formed between the first side wall 6 and the second side wall 7. In Figure 1, arrows indicate the direction in which the manure to be dried is conveyed. Ultimately, the dried manure, at a drive roller lid, falls off the fourth belt conveyor 10 onto a discharge conveyor belt 13, which is indicated by a dashed line. Each belt conveyor 5, 8, 9, 10 comprises an endless perforated conveyor belt 5a, 8a, 9a, 10a which can be set in motion with the aid of a drive roller 11a, lib, lie, lid, which is driven by a motor (not shown) , the drive roller 11a, lib, lie, lid being located at an exit end of the belt conveyor 5, 8, 9, 10. A diverting roller 12a, 12b, 12c, 12d is located at the other end. Each conveyor belt 5a, 8a, 9a, 10a has a conveying side 21 and a return side 22, the conveyor side 21 being located at the top and being suitable for conveying the manure. The return side 22 is located on the bottom of the belt conveyors 5, 8, 9, 10. The conveyor belt 5a, 8a, 9a, 10a is driven in such a manner that its conveying side 21 moves from the entry section to the drive roller 11a, lib, lie, lid. The belt conveyors 5, 8, 9, 10 divide the drying chamber 20 formed between the side walls 6, 7 in the vertical direction into bottom compartments 23, which are delimited in the lateral direction by the first side wall 6 and the second side wall 7 and in the vertical direction by the conveying side 21 and the return side 22 of the conveyor belt 5a, 8a, 9a, 10a of the corresponding belt conveyor 5, 8, 9, 10, and top compartments 24, which in the lateral direction are likewise delimited by the first side wall 6 and the second side wall 7 and in the vertical direction by the conveying side 21 of a belt conveyor 8, 9, 10 and the return side 22 of the belt conveyor 5, 8, 9 located immediately above it . Figure 2 shows a known device, in which the bottom compartments 23 are in communication with a pressure chamber 14 via an associated inlet opening 30. The top compartments 24 are in communication with the environment via an associated outlet opening 31. The pressure chamber 14 preferably extends along the entire first side wall 6. Air is blown into the pressure chamber 14 with the aid of one or more fans 17. The air which is blown into the pressure chamber 14 is preferably hot air. The air blown into the pressure chamber 14 may come, for example, from a shed area in which manure-producing poultry are located. During operation, the pressure which prevails in the pressure chamber 14 is higher than a pressure of the environment. As a result, a flow of air is generated from the pressure chamber 14 via the drying chamber to the environment . For each belt conveyor 5, 8, 9, 10, a partition element 32 is arranged on the underside, extending between the first side wall 6 and the second side wall 7, thus closing off the perforations on the return side of the conveyor belts 5a, 8a, 9a, 10a. The pressure difference between the bottom compartments 23 and the top compartments 24 will therefore result in a flow of air from a bottom compartment 23 of a belt conveyor 5, 8, 9, 10, via the perforations on the conveying side of the conveyor belt 5a, 8a, 9a, 10a, to the top compartment 24 of the corresponding belt conveyor. The direction of the air flow is indicated by arrows in Figure 2. In the device according to the invention, which is shown in Figure 3, a bottom compartment 23 belonging to a belt conveyor 5, 8, 9 and the top compartment 24 of the belt conveyor 8, 9, 10 located immediately below it are in communication with either the pressure chamber 14 or the environment. For this purpose, inlet openings 15, 16 are arranged in the first side wall 6 and outlet openings 18a, 18b are arranged in the second side wall 7. The bottom compartment 23 of the bottom belt conveyor 10 is in communication with the environment via an outlet opening 19, while the top compartment 24 of the top belt conveyor 5 is in direct communication with the environment on the top side. The inlet openings 15, 16 and the outlet openings 18a, 18b preferably extend over the entire length of the side wall 6 or the side wall 7. In the exemplary embodiment illustrated, the inlet openings 15, 16 and/or the outlet openings 18a, 18b form a single common opening for the compartments in question. The compartments which have a common opening are separated from one another by the return side 22 of the conveyor belt 5a, 8a, 9a in question. The common openings extend above and below the return side 22 of the corresponding conveyor belt 5a, 8a, 9a. The common openings are divided into a top part and a bottom part by the return side 22 of the conveyor belt 5a, 8a, 9a, each part having a predetermined flow-through area. During operation, the pressure in the pressure chamber 14 is higher than ambient pressure. Consequently, the pressure in the compartments of the drying chamber 20 which are in communication with the pressure chamber 14 via the inlet openings 15, 16 in the first side wall 6 is also higher than ambient pressure. In the other compartments, a pressure which substantially corresponds to ambient pressure prevails . Since the conveyor belt 5a, 8a, 9a, 10a of the belt conveyors 5, 8, 9, 10 is provided with perforations, a flow of air will be generated from a compartment which is in communication with the pressure chamber 14 to a compartment which is in communication with the environment. The corresponding compartments are separated from one another by the conveying side 21 of the conveyor belt 5a, 8a, 9a, 10a. In the device according to the invention, for example at the belt conveyor 8, a flow of air will be formed from the top compartment 24 of the belt conveyor 8 to the bottom compartment 23 of the belt conveyor 8. In the case of the belt conveyor 9, a flow of air will be generated from the associated bottom compartment 23 to the associated top compartment 24. The direction of these air flows are indicated by arrows in Figure 3. In the first case, the air flows from the top downwards through the manure which is to be dried, and in the second case the air flows from the bottom upwards. The resistance which the air flow experiences will be greater in the first case than in the second case. To ensure that substantially equal quantities of air flow through each layer of manure, the flow-through areas of the inlet openings 15, 16 and/or outlet openings 18a, 18b can be adapted. The conveyor belt is supported by support bars (not shown) which extend between the first side wall 6 and the second side wall 7, in order to prevent it from sagging. The support bars are removable and can be arranged at a plurality of vertical positions in the device. The ratio between the flow- through areas of the top part and the bottom part can be adjusted according to requirements by changing the distance between the conveying side and the return side of the conveyor belt in question, for example by moving the abovementioned support bars to a position which corresponds to the desired distance. Since the compartments which are separated by the return side 22 of a conveyor belt 5a, 8a, 9a are at substantially equal pressure, it is not necessary for the perforations on the return side 22 of the conveyor belt 5a, 8a, 9a to be closed off. A partition element 32 in the form of a separating plate or a separating canvas can therefore be omitted, so that there are no problems with a build-up of dirt or manure and/or with wear. With this configuration of the device according to the invention, optimum use is made of the drying capacity of the air which is present in the pressure chamber 14. The device according to the invention may be of more compact design, i.e. less high, than the known device, the device according to the invention having the same flow-through area for the flow of air as the known device. This is because of the fact that the required seal between the side walls and the partition element 32 of the known device can be dispensed with. The device according to the invention is of simple design, is lighter than the known device and can be produced at low cost due to the saving on material for the partition element 32. In the preferred embodiment of the device according to the invention which is illustrated, the top compartment 24 of the first belt conveyor 5 is open at the top side. Obviously, the top compartment 24 of the first belt conveyor 5 may be closed on the top side, so that the top compartment 24 is in communication with the environment only via an outlet opening arranged in a second side wall . If desired, all the openings may be arranged in the same side wall, in which case a manifold and a system of pipes ensure separation between the feed air and the discharge air. The device as described is preferably composed of segments of a predetermined length. Linking a plurality of segments produces a device of the desired length. The openings in the side walls preferably extend over the entire length of the device. However, it is also possible to provide a plurality of openings for a single compartment by closing off the corresponding opening at regular intervals in the longitudinal direction. If a segment only has openings for connection to the air-supply device and the adjoining segment only has openings for communication with the environment, a flow of air which is present at least during operation in the device will also have a directional component in the longitudinal direction of the device. This extends the residence time of a control volume of air in the device, with the result that the drying capacity of the device increases . The above-described embodiment of a device according to the invention is given as a non-limiting example. It will be clear to a person skilled in the art that various changes and modifications to the exemplary embodiment are possible without departing from the scope of the invention as defined in the appended claims . For example, it will be clear that the number of belt conveyors may differ from the abovementioned number of four belt conveyors . Furthermore, it will be clear that each of the rollers of a belt conveyor may be driven, for example by separate motors or via a transmission system with the aid of a single motor. Moreover, it is not necessary for all the belt conveyors to be of equal width, so that the side walls are not parallel. It is also possible for the pressure chamber 14 to be connected to an air-discharge device, so that the pressure in the pressure chamber 14 is lower than ambient pressure. In this case, a flow of air will be generated from the environment via the drying chamber 20 to the pressure chamber 14. In another variant of the device according to the invention, the drying chamber 20 is connected to a suction installation via the outlet openings 18a, 18b, 19, so that the pressure difference increases across the drying chamber 20. The device may be divided into two sections in the horizontal direction, in which case the air which has flowed through the bottom section is guided through to the top section, in order to dry the manure contained therein. In this embodiment, the pressure chamber 20 is only in communication with the bottom section, while a suction installation is connected to the top section.

Claims: CLAIMS 1. Device for dehydrating a mass, comprising a drying chamber (20) , which is delimited by a first side wall (6) and a second side wall (7), at least two belt conveyors (5, 8, 9, 10), which are arranged one above the other in the drying chamber (20) and extend between the first side wall (6) and the second side wall (7) , each of the belt conveyors comprising an endless conveyor belt which is provided with perforations and has a conveying side (21) and a return side (22) , and each belt conveyor (5, 8, 9, 10) being associated with a bottom compartment (23) and a top compartment (24) , the bottom compartment (23) being defined by the conveying side (21) and the return side (22) of the belt conveyor (5, 8, 9, 10) in question, and the top compartment (24) being defined by the conveying side (21) of the belt conveyor (8, 9, 10) in question and the return side of the belt conveyor (5, 8, 9) located immediately above it, characterized in that, at least during operation, a pressure difference prevails between a top compartment (24) of a belt conveyor (5, 8, 9, 10) and the bottom compartment (23) of the belt conveyor (5, 8, 9, 10) in question, and in that a pressure in the top compartment (24) of a belt conveyor (8, 9, 10) and a pressure in the bottom compartment (23) of the belt conveyor (5, 8, 9) located directly above it are substantially equal. 2. Device according to claim 1, characterized in that a bottom compartment (23) belonging to a specific belt conveyor (5, 8, 9) and the top compartment (24) of the belt conveyor (8, 9, 10) located immediately below it are both provided with either an inlet opening (15, 16) for the admission of air or an outlet opening (18) for discharging air. 3. Device according to claim 2, characterized in that the said inlet opening (15, 16) and outlet opening (18) are designed as two openings which merge into one another and thus define a single common opening (15, 16, 18) . 4. Device according to claim 1, 2 or 3, characterized in that the distance between the conveying side (21) and the return side (22) of each of the belt conveyors (5, 8, 9, 10) is adjustable . 5. Device according to claim 4, characterized in that the distance between the conveying side (21) and the return side (22) of each of the belt conveyors (5, 8, 9, 10) can be adjusted with the aid of removable support bars . 6. Device according to one of claims 2-5, characterized in that each compartment is provided with a plurality of inlet openings (15, 16) or outlet openings (18) . 7. Device according to claim 6, characterized in that projections of the inlet openings (15, 16) onto a plane running through the first side wall (6) in the longitudinal direction of the device are offset with respect to projections of the outlet openings (18) onto the plane running through the first side wall (6) .

Inventors: AERTS ALOISIUS JOHANNES, AERTS, ALOISIUS, JOHANNES
Applicants: AERTS ALOISIUS JOHANNES, POULTRY BEHEER B V, AERTS, ALOISIUS, JOHANNES, POULTRY BEHEER B.V.
Application year: 2000
Main classification: F26B17
IPC codes: F26B17