Combined modular dryer for cereals in the form of grains and ears

Abstract

The invention relates to a combined dryer (100) for maize or similar crops, suitable for both grains and ears, wherein the dryer comprises a plurality of modules (50), wherein each module comprises at least one drying cell (10) intended to receive the maize, a hot air generator (30), and an air distribution network (35) for sending the hot air into the cell, and wherein the dryer comprises an automatic filling system (20) configured to uniformly fill each cell (10), wherein each cell (10) comprises, on its bottom, at least one drying duct (16) perforated with a plurality of holes through which the hot air blown by the generator flows, wherein the holes are variably spaced along the duct so as to ensure a constant airflow through the maize, and wherein the dryer further comprises an air recirculation tunnel (352) for re-injecting slightly moist used air into the cell.

Description

[0001] DESCRIPTION

[0002] TITLE: Modular mixed dryer for grain and ear cereals

[0003] Technical field

[0004] The present invention belongs to the field of systems for drying cereals, in particular corn, and relates more particularly to a mixed (or multi-purpose) modular dryer for cereals which may be in the form of grains or ears. The invention finds a direct, but not exclusive, application in the drying of corn.

[0005] State of the art

[0006] Grain dryers have been known for a long time.

[0007] These systems are used in agriculture to reduce the moisture content of grain after harvest. Drying corn, for example, is a crucial step because high moisture levels can lead to mold growth and grain deterioration, affecting both the quality and market value of the product.

[0008] There are different types of corn dryers, including batch dryers and continuous dryers. Batch dryers process corn in separate batches and often require the grain to be manually unloaded and loaded. Continuous dryers, on the other hand, allow the grain to pass through the dryer in a constant stream, which is more efficient for large operations.

[0009] The drying process typically uses hot air to evaporate moisture from the grain. The temperature and airflow must be carefully controlled to avoid damaging the grain. Drying can be achieved using a variety of energy sources, including natural gas, propane, electricity, or even renewable energy sources like biomass.

[0010] The design and efficiency of corn dryers have evolved over time, with improvements in reducing energy consumption, increasing drying capacity, and minimizing grain damage.

[0011] We generally know bin dryers with Ampliroll arms (registered trademark). These are bins with ventilated bottoms, placed directly on the ground, mainly for drying cereals.

[0012] These skips generally offer small volumes, due to the regulatory dimensions authorized on the road, and require numerous tedious handling operations using a lifting hook (removal from the truck, placing on the ground, putting back on the truck, etc.).

[0013] There are of course other, less rudimentary solutions for drying cereals and corn in particular.

[0014] Document FR2445101A1 describes, for example, a blower dryer for corn on the cob.

[0015] As the above document shows, in the case of corn and other similar cereals, dryers are only compatible with one form of corn, in grain or in cob, but not both at the same time.

[0016] Corn on the cob is usually dried on an inclined plane because, due to the gap structure and the consistency of the cobs when packed, they can fill the inclined plane fairly evenly (with a substantially constant filling height) and be easily removed by gravity via a trapdoor located at the bottom of the inclined plane. In contrast, in the case of grains, inclined planes are unsuitable because the grains tend to accumulate at the bottom of the inclined plane during filling. This produces a settling of the grains in the deepest area and, in return, a lower filling thickness at the top of the inclined plane. Hot air naturally tends to escape through the thin areas, thus creating persistent moisture in the thick areas. This can quickly lead to rotting of the product.

[0017] Furthermore, due to climate change, with increasingly hot summers in grain-growing regions, harvest windows have become shorter. As a result, to speed up harvests, producers are harvesting corn kernels with combines rather than cobs, and therefore need a dryer suitable for both cobs and kernels.

[0018] To the applicant's knowledge, there is currently no multi-purpose system capable of drying both ears and grains.

[0019] As mentioned above, corn dryers are designed specifically for one type or the other due to differences in drying requirements. Corn kernels and corn cobs have different moisture levels, densities, and airflow requirements, making drying them simultaneously in a single unit a complex process.

[0020] US4212115 describes a corn drying apparatus with a drying area divided into several compartments and a system of upper and lower plenums. This system allows the hot air to be directed either from top to bottom or from bottom to top through the corn, which is essential for achieving uniform moisture content in the corn. The design of this apparatus also includes a perforated floor for better air circulation and doors allowing manual control of the air passage.

[0021] This solution is designed to optimize the drying of corn grains, in particular with hot air circulation adapted to the consistency of the grains and their specific humidity levels.

[0022] Summary of the invention

[0023] The present invention aims to overcome all or part of the drawbacks of the prior art set out above by proposing an innovative solution for drying corn both in grains and on cobs.

[0024] One objective of the invention is therefore to propose a versatile, efficient and energy-saving system.

[0025] To this end, the present invention relates to a dryer for a product such as cereals or the like in two different forms, grains and ears, comprising a plurality of modules, each module comprising at least one drying cell intended to receive the product, a hot air generator and its air distribution network for sending the hot air into said cell.This dryer is remarkable in that it comprises an automatic filling system configured to uniformly fill each cell, that is to say to a substantially constant height, in that each cell comprises on its bottom at least one drying duct perforated with several holes and crossed by the hot air blown by said generator, said holes having a variable spacing along said duct so as to ensure a constant air flow passing through the product, and therefore uniform drying, and in that it further comprises an air recycling tunnel to recover the used air which is partially loaded with humidity and reinject it into the cells with or without reheating.

[0026] Due to the uniform filling and the hot air flow and temperature adjustments allowed, the dryer is versatile and adapts to both grains and cobs, ensuring uniform drying in both cases.

[0027] According to one embodiment, each module comprises two adjacent cells and a single hot air generator, the distribution network comprising a primary channel with two branches to supply the two cells.

[0028] Advantageously, each cell includes a motorized horizontal hopper equipped with a conveyor belt to evacuate the product to a recovery conveyor located at the rear of the dryer.

[0029] More particularly, each cell comprises a guillotine hatch, the opening of which allows the product to be discharged by gravity onto the recovery conveyor, said hatch having one or more automatically controlled positions, each of which corresponds to a certain degree of flowability of the product.

[0030] According to one aspect of the invention, each cell comprises at least one flap at its upper opening and upper registers connected to the recycling tunnel, the dryer being configured to operate in an open circuit, in which the flap is open and the upper registers closed, or in a closed circuit, in which said flap is closed and said registers are open to reinject the used air into the recycling tunnel.

[0031] More specifically, the recycling tunnel is common to all cells.

[0032] According to an advantageous aspect, a sealing strip is placed laterally between the drying duct and the bottom of the cell, said strip defining a gap to allow a layer of hot air to pass through and preventing the product from passing through.

[0033] According to one embodiment, each hot air generator comprises several burners for adjusting the temperature of the hot air.

[0034] Furnaces also include a fan to blow hot air into the drying ducts.

[0035] Advantageously, the modules can be connected to each other without any masonry footprint on the ground.

[0036] The fundamental concepts of the invention having just been set out above in their most elementary form, other details and characteristics will emerge more clearly on reading the description which follows and with reference to the appended drawings, giving by way of non-limiting example an embodiment of a mixed dryer for cereals, in accordance with the principles of the invention.

[0037] Presentation of the drawings

[0038] The figures are provided for purely illustrative purposes to provide a better understanding of the invention without limiting its scope. The various elements may be represented schematically and are not necessarily to scale. Throughout the figures, identical or equivalent elements bear the same numerical reference.

[0039] It is thus illustrated in:

[0040] [Fig. 1]: a perspective view of a mixed dryer according to one embodiment of the invention;

[0041] [Fig. 2]: another perspective view, rear, of the mixed dryer showing the conveyor for recovering the dried product;

[0042] [Fig. 3]: an exploded view of a drying module of the mixed dryer;

[0043] [Fig. 4]: a partial view of the dryer, showing the detail of a cell; [Fig. 5]: a rear perspective of a cell of the dryer;

[0044] [Fig. 6]: a front perspective of a dryer cell;

[0045] [Fig. 7]: a partial view of the dryer, showing the detail of the filling system;

[0046] [Fig. 8]: a truncated view of the isolated filling system;

[0047] [Fig. 9]: a partial view of the dryer, showing the detail of a hot air generator and its air distribution network;

[0048] [Fig. 10]: a perspective of a dryer cell, showing the drying ducts at the bottom of the cell;

[0049] [Fig. 11]: a section of the cell in figure 10 along plane A - A.

[0050] Detailed description of embodiments

[0051] It should be noted that certain technical elements well known to those skilled in the art are recalled here to avoid any insufficiency or ambiguity in the understanding of the present invention.

[0052] In the embodiment described below, reference is made to a mixed modular dryer, mainly intended for drying cereals in different shapes or morphologies (grains and ears) such as corn. This non-limiting example is given for a better understanding of the invention and does not exclude the use of the dryer for drying other materials, in particular hay, wood chips and the like.

[0053] In the remainder of the description, the terms “cereals” and “product” refer indifferently to corn.

[0054] Figures 1 and 2 represent a mixed dryer 100 comprising a plurality of juxtaposed drying cells 10, a motorized filling system 20, placed above the cells and allowing each of them to be filled at a time with the cereals to be dried, hot air generators 30 and their air distribution and recycling networks 35, located at the front of the cells 10 and allowing a flow of hot air to be blown into them, and a recovery conveyor 40 located at the rear of the cells 10 to evacuate the dried cereals outside the dryer 100.

[0055] The mixed dryer 100, due to its plurality of cells 10 and hot air generators 30, is in the form of a modular system adaptable according to the needs of the users. Indeed, the mixed dryer 100 comprises several drying modules 50 each consisting of two adjacent cells 10 and a hot air generator 30 with its air distribution and recycling network 35 supplying the two cells.

[0056] According to the illustrated embodiment, the mixed dryer 100 has six modules 50, one of which, located at the end, is delimited by a broken line in figure 1. Figure 3 represents an exploded view of a drying module 50, to better visualize its various components.

[0057] This modularity allows the mixed dryer 100 to adapt to different drying capacities in terms of volumes of cereals processed, but also to adapt to different spaces by the possibility of arranging the modules in different ways: in one or more rows, parallel or perpendicular, etc. This is all the simpler since the mixed dryer 100 does not require any masonry footprint and can be installed and fixed by quick fixing means.

[0058] In addition, the mixed dryer 100 may initially comprise one or a few modules 50, to which additional modules may be progressively connected depending on an evolving industrial need, for example. Figure 2 shows the mixed dryer 100 in rear view and provides a better view of the recovery conveyor 40 which allows the dried product to be evacuated at the outlet of the cells 10.

[0059] Figures 4 to 6 show the drying cells 10 in more detail.

[0060] Each cell 10 has a parallelepiped shape of rectangular section, reminiscent of that of a conventional skip, and comprises a horizontal hopper 11 which forms its bottom, a guillotine hatch 12 allowing the cell to be emptied when the belt of the hopper 11 starts to rotate, flaps 13 at the level of the upper filling opening of said cell, ventilation and air intake registers, lower 14 and upper 15, and drying conduits 16 passing through the cell 10 lengthwise opposite the lower registers.

[0061] The cells 10 thus constitute the space for drying the cereals and allow the execution of different programmed drying cycles as explained below. The hopper 11, according to one embodiment of the invention, uses the sealing principles described in patent FR3091860 in the name of the applicant.

[0062] This patent describes a belt conveyor for transporting bulk products, comprising a chassis, a conveyor assembly, and a motorized drive device, the conveyor assembly comprising a plurality of transverse pallets coupled to at least one chain driven by a motor pinion of the drive device and on which a flexible conveyor belt is fixed, said conveyor comprising at each lateral edge of the conveyor assembly: a sliding base placed above the ends of a portion of the transverse pallets and below the conveyor belt, and a sealing block fixed to a side wall of the conveyor and pressing the conveyor belt against said sliding base.

[0063] The hopper 11 allows, by rotation of its horizontal conveyor belt, to direct the dried product towards the outlet of the cell 10. The movement of the conveyor belt of the hopper 11 is then accompanied by the progressive opening of the guillotine hatch 12.

[0064] The guillotine hatch 12 is mounted to slide at the rear face of the cell 10, in a direction substantially perpendicular to the hopper 11, and allows, when rising, passage to the dried product carried by the rotation of the hopper so that it can be evacuated by the recovery conveyor 40.

[0065] The guillotine hatch 12 has, for example, several automatically controlled opening heights, each corresponding to a type of product, in order to optimize the emptying operation of the cell 10. In fact, cereals do not have the same flowability (or viscosity), so that the choice of a suitable opening height makes it possible to avoid overflow of the product during emptying.

[0066] Of course, the guillotine hatch 12 remains in the closed position during the filling of the cell 10 with the product to be dried, which filling is carried out via the upper opening of the latter with the shutters 13 open or partially open.

[0067] The shutters 13, according to the illustrated embodiment, are rolling and arranged in symmetrical pairs on each cell 10.

[0068] Indeed, the two rolling shutters 13 of each cell 10 are mounted on a central axis 135 located substantially in the middle of the upper opening of said cell, perpendicular to it. Thus, in each cell 10, the rolling shutters 13 open from the ends towards the center of the cell, as indicated by the two opposite arrows in Figure 6, by winding around the central axis 135 to be stored in a box provided for this purpose. During drying, the shutters 13 can be open or closed depending on the nature of the drying cycle, which can be in an open circuit to let the air escape to the outside or in a closed circuit to recycle the hot air partially saturated with humidity.

[0069] When filling the cells 10, the shutters 13 are necessarily open, totally or partially depending on the position of the filling system 20 which moves along each cell.

[0070] Figures 7 and 8 represent the filling system 20, according to an exemplary embodiment of the invention, comprising a transverse distribution conveyor 21 mounted to slide on a carriage 22, itself sliding on two longitudinal rails 225 running along the dryer 100, and a longitudinal conveyor 23 for transporting the product towards the transverse distribution conveyor.

[0071] The transverse distribution conveyor 21 ends with two pouring mouths 211 each opening into the cell 10, said mouths being astride the central axis 135 of the flaps 13 according to the example illustrated.

[0072] The transverse distribution conveyor 21 is motorized and slides along the carriage 22 to pour the product at different locations in the cell 10 and thus ensure the most uniform layer-by-layer filling possible, i.e. with a substantially constant filling height along the entire length of the cell. This makes it possible to avoid the formation of accumulation zones with different heights in which the drying will not have the same effect and will therefore not be uniform.

[0073] Preferably, the transverse distribution conveyor 21 describes an alternating “back and forth” movement along the cell 10, to achieve continuous and homogeneous filling.

[0074] Furthermore, the cell 10 may include level sensors for sending filling instructions to the filling system 20 via a control system, making it possible to guarantee uniform horizontal filling.

[0075] Thus, regardless of the quantity of product to be dried, the filling system 20 ensures uniform horizontal filling and therefore uniform drying of the entire product, including for low product heights in the cell. Before it is poured into the cell 10, the product arrives on the transverse distribution conveyor 21 via the longitudinal conveyor 23 which is provided with a ramp arranged so that the product falls exactly onto the transverse distribution conveyor 21.

[0076] As soon as the filling of a cell is complete, the drying cycle can begin thanks to the actuation of the hot air generator 30 supplying said cell.

[0077] Figure 9 shows the hot air generator 30, according to one embodiment of the invention, comprising one or more burners (not shown), a fan 31 and an air distribution and recycling network 35.

[0078] The air distribution and recycling network 35 comprises a primary hot air supply channel 351 and a recycling tunnel 352 common to all the cells.

[0079] In fact, the recycling tunnel 352 is made up of connected sections and can therefore be extended if additional modules are added to the dryer 100.

[0080] The hot air generators 30 may have different power sources. Preferably, the power source used is gas. Each generator 30 includes several ignition ramps to provide different heating levels depending on the air flow rate required to dry the product. It should be noted that to dry cereals and seeds, the air must be at a temperature between 38 and 40°C.

[0081] If the temperature is below this range, drying will take longer and therefore require more energy. On the contrary, if the air temperature is above the indicated range, drying may damage the grains.

[0082] Indeed, temperatures above 40°C can destroy the germ, which destroys the seed. On the other hand, for grains intended for food and not for seed, the condition of the germ is of little importance and drying can be carried out at higher temperatures.

[0083] For these settings, each hot air generator 30 includes modulating valves allowing the gas flow to be adapted according to the air flow and the calories required for drying.

[0084] The fan 31 comprises a turbine for sucking in hot air and sending it into the primary supply channel 351.

[0085] This air suction can be carried out either in an open circuit or in a closed circuit to recover the air already used, which is warmer than the ambient (outside) air, via the recycling tunnel 352 which collects this air from the upper registers 15 of the cells 10.

[0086] The primary channel 351 is connected to the outlet of the fan 31 and has a shape which separates into two branches to distribute the flow of hot air over the two cells 10 of the same drying module 50 as shown in FIGS. 1 and 3.

[0087] The lower registers 14 then allow the flow of hot air to be admitted into the cells 10, thanks to their blades (in the form of shutters) controlled by servomotors to adjust the opening and therefore regulate the air flow.

[0088] If a cell 10 is empty, its lower registers 14 are closed, thus preventing the entry of hot air. Pressure sensors are provided to detect excess pressure at the closed cell and send an instruction to regulate the air flow sent by the fan 31.

[0089] The fan 31 is adaptive for this purpose and allows the air flow to be regulated in order to respect a preset pressure set at the start.

[0090] The drop in air pressure is necessarily accompanied by an adjustment of its temperature.

[0091] Hot air enters cell 10 through lower intake registers 14 and passes directly into drying ducts 16.

[0092] Figures 10 and 11 show these conduits 16 in a cell 10.

[0093] According to the example illustrated, cell 10 comprises four conduits 10: two central conduits and two lateral conduits.

[0094] Alternatively, depending on the size of the cell, the number of ducts may vary.

[0095] The conduits 16 are perforated sheets and thus form strainers for the hot air so that the latter rises into the cell and passes through the product to be dried.

[0096] Each duct 16 has thousands of small holes distributed along its length, for example 3 to 4 mm in diameter to prevent grain from falling out. These holes are not visible in the figures.

[0097] In order to ensure the most uniform drying possible, the holes on each duct 16 have a variable spacing. More particularly, the spacing becomes increasingly tighter towards the rear of the duct 16, i.e. towards the guillotine hatch 12. Indeed, due to the compression it undergoes in the duct 16, the hot air tends to exit more through the first holes of the duct, i.e. those located at the front of the duct, which promotes the drying of the product located at the front of the cell to the detriment of the product located at the rear. In order to compensate for this differential in the drying level, and therefore in the residual level of the humidity rate, the spacing of the holes along the ducts 16 is adjusted so as to obtain the same flow of hot air passing through the product and therefore, ultimately, uniform drying.

[0098] It should be noted that in the prior art solutions, there may be a difference in humidity levels of around 4% between the front and the rear of the drying bin.

[0099] In addition, it is important that the seeds reach a predetermined moisture content, for example between 12 and 13%.

[0100] Thus, along each drying duct 16, the holes are distributed with a decreasing spacing from the front to the rear of the duct, i.e. following the direction of penetration of the hot air into said duct. A numerical simulation makes it possible to fix the rule for decreasing this spacing to obtain the same flow of rising air throughout the cell.

[0101] Between the conduits 16 and the conveyor belt of the hopper 11, the lateral sealing is ensured by a flexible strip, for example made of plastic, which leaves sufficient clearance, of approximately 3 mm, to create an air gap which dries a part of the product located at this level and which could not be dried otherwise. This sealing strip also ensures its sealing function to prevent the product from falling back.

[0102] It should be noted that a conventional soft rubber mud flap would not work because it would trap air by pressing down with a pressure that prevents its release by the air flow.

[0103] By passing through the product contained in cell 10, the hot air becomes charged with humidity and can either be evacuated through the upper opening of the cell with the flaps 13 open (open-air configuration) in the case of open-circuit drying, or be reinjected into the recycling tunnel 352 via the upper registers 15 in the case of closed-circuit drying.

[0104] The closed circuit is, for example, advantageous at the end of the season because the recovered hot air is not completely saturated with humidity and can be perfectly reused with or without reheating.

[0105] In open circuit, the roller shutters 13 are open to allow air to escape, while the upper registers 15 are closed to prevent air from entering the recycling tunnel 352.

[0106] Conversely, in a closed circuit, the roller shutters 13 are closed to keep the used air in the circuit, while the upper registers 15 are open to recover this used air in the recycling tunnel 352.

[0107] The recycling tunnel 352 includes inlet valves 353 at the inlet of each hot air generator 30. When these valves are open, the recovered air passes back into the fan 31 to be sent into the primary channel 351 and again into the cells 10.

[0108] Advantageously, the dryer 100 as designed makes it possible to adapt to the needs of each cell depending on whether it is filled or not, with what type of product, depending on the external conditions, etc.

[0109] For example, if a cell has been in a drying cycle for several days, it will have a low humidity level. On the other hand, the last cell to be filled will have a higher humidity level. Therefore, the warm air already used and slightly loaded with moisture will be sufficient for drying or at least for the beginning of drying.

[0110] Furthermore, the air distribution is based on periodic sampling to measure the humidity levels, in order to adjust the program of each cell between drying in slightly humid recycled air or drying in dry air. The sampling for humidity measurement can be automated in particular by means of the mobile trolley 22 on which automatic sampling means can be installed.

[0111] The 352 recycling tunnel is also equipped with vacuum sensors, allowing for a balance between the suction and blowing of air in the tunnel. Indeed, the suction must not be stronger than the blowing by the fans to avoid creating vacuums.

[0112] If a depression is detected, the flaps 13 of certain cells 10 can be opened to create an air intake and so that the fans 31 have another source of air to reduce the depression and rebalance the pressures in the recycling tunnel 352.

[0113] These operations, as well as the overall operation of the 100 mixed dryer, are controlled automatically via a programmable controller.

[0114] Finally, the dry product is then conveyed by the recovery conveyor 40 to be processed in another part not concerned by the present invention (continuity to other ginning, calibration, etc. equipment).

[0115] It is apparent from the present description that certain non-essential elements of the dryer may be modified, replaced or deleted without departing from the scope of the invention defined by the following claims. For example, the filling, hot air generation and emptying operations may be carried out by alternative means and systems commonly used in the art.

Claims

CLAIMS 1. A dryer (100) for a product such as cereals or the like in two different forms, grains and ears, comprising a plurality of modules (50), each module comprising at least one drying cell (10) intended to receive the product, a hot air generator (30) and its air distribution network (35) for sending the hot air into said cell, said dryer being characterized in that it comprises an automatic filling system (20) configured to uniformly fill each cell (10), in that each cell (10) comprises on its bottom at least one drying duct (16) perforated with several holes and crossed by the hot air blown by said generator, said holes having a variable spacing along said duct so as to ensure a constant air flow passing through the product, and in that it further comprises an air recycling tunnel (352).

2. Dryer according to claim 1, in which each module (50) comprises two adjacent cells (10) and a single hot air generator (30), the distribution network (35) comprising a primary channel (351) with two branches to supply the two cells.

3. Dryer according to claim 1 or 2, in which each cell (10) comprises a motorized horizontal hopper (11) provided with a conveyor belt for evacuating the product towards a recovery conveyor (40).

4. Dryer according to claim 3, in which each cell (10) comprises a guillotine hatch (12) the opening of which allows the product to be evacuated by gravity onto the recovery conveyor (40), said hatch having one or more automatically controlled positions.

5. A dryer according to any preceding claim, wherein each cell (10) comprises at least one flap (13) at its upper opening and upper registers (15) connected to the recycling tunnel (352), said dryer being configured to operate in an open circuit, in which the flap is open and the upper registers closed, or in a closed circuit, in which said flap is closed and said registers are open to reinject the used air into the recycling tunnel.

6. Dryer according to any one of the preceding claims, in which the recycling tunnel (352) is common to all the cells (10).

7. Dryer according to any one of the preceding claims, in which a sealing strip is placed laterally between the drying duct (16) and the bottom of the cell (10), said strip defining a clearance to allow a blade of hot air to pass through and preventing the passage of the product.

8. A dryer according to any preceding claim, wherein each hot air generator (30) comprises a plurality of burners for regulating the temperature of the hot air.

9. A dryer according to any preceding claim, wherein each hot air generator (30) comprises a fan (31) for blowing hot air into the drying duct (16).

10. Dryer according to any one of the preceding claims, in which the modules (50) are connectable to each other without any masonry footprint on the ground.

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