Product drying system

Abstract

Product drying system (1) comprising: - a ventilation system (60) for circulating the air present in the room (10), - a condensation drying system (20) configured to capture moisture from the air in the room (10) and condense said moisture into liquid water droplets, thus drying the products, - a desiccation drying system (30) configured to dry the products, characterized in that system (1) is configured to operate a condensation drying phase comprising iteratively activating and deactivating the condensation drying system (20), and in that a desiccation drying phase comprising iteratively activating and deactivating the desiccation drying system (30). Figure for the abstract: Figure 1

Description

Title of the invention: Product drying system FIELD OF INVENTION

[0001] The present invention relates to a product drying system, and more particularly to a system for drying plant products. Technological background

[0002] In the field of product drying, several drying systems are known.

[0003] A first known system is a hot air drying system. The system One method involves blowing hot air onto the products to dry them. A second known system is convection drying. This system creates air movement to carry moisture away from the products to be dried. The system may include a fan to create air movement or by placing the products on a hot plate to dry them by convection. A third known system is conduction drying. This system uses a direct heat source to dry the products. The heat source can be a hot plate or any other heating element placed in direct contact with the products. Finally, a fourth known system is dehumidification drying. This system uses a dehumidifier to remove moisture from the air. Air is then blown onto the products to dry them.

[0004] This fourth system is more particularly the subject of the present invention.

[0005] In general, a dehumidification drying system is particularly effective for drying products. However, a major drawback of this type of system is that it requires a large amount of energy to ensure efficient drying. There is currently a drive to reduce the amount of energy needed to prepare products fit for consumption, which explains why existing drying systems need to be redesigned. Another disadvantage of these drying systems is that it can be difficult to dry the components uniformly, preventing surface crusting.

[0006] The product drying system described here seeks at least partially to address the problems outlined. Summary of the invention

[0007] Thus, the invention relates to a product drying system comprising: - a room including an enclosure, in which the enclosure is advantageously thermally insulated, the enclosure being intended to receive the products to be dried, the system further comprising: - a fan allowing for air circulation in the room, - a condensation drying system comprising a condenser-type heat exchanger, an evaporator-type heat exchanger, an expansion valve, a compressor and at least one fan, in which the condensation drying system is configured to capture moisture from the air in the room and condense said moisture into liquid water droplets, thus allowing the products to dry, - a desiccant drying system comprising a desiccant wheel, a heating element and at least one fan, said desiccant drying device being configured to dry the products, characterized in that the system is configured to operate a condensation drying phase during which said system is configured to implement, iteratively until a first condition is met, an activation of the condensation drying system and a deactivation of the condensation drying system, and in that Once the first condition is met, the system is configured to operate a desiccation drying phase during which said system is configured to implement, iteratively until a second condition is met, an activation of the desiccation drying system and a shutdown of the desiccation drying system.

[0008] Thanks to these features, the system enables particularly efficient drying of the products through the use of condensation and desiccant drying systems. Furthermore, the iteratively implemented shutdown phases reduce energy costs, as the systems are periodically switched off, and prevent surface crusting of the products, since the homogenization phases allow the moisture contained within the product to rise to the surface. Finally, the activation / shutdown phases of the condensation and desiccant drying systems simulate natural drying of the product by mimicking day and night cycles.

[0009] Depending on different aspects, it is possible to foresee one and / or the other of the characteristics below taken alone or in combination.

[0010] According to one embodiment, the first condition is a first humidity threshold to be reached in the room, for example a humidity threshold of 30%.

[0011] According to one embodiment, the second condition is a second humidity threshold to be reached in the room, for example a humidity threshold of less than 5%.

[0012] According to one embodiment, the second humidity threshold is lower than the first humidity threshold.

[0013] According to one embodiment, the system is configured to operate, prior to the activation of the condensation drying system, a temperature rise inside the room, said temperature rise being obtained by the activation of the desiccation drying system and the room fan or the condenser-type heat exchanger.

[0014] According to one embodiment, during the condensation drying and / or desiccation drying phases, the system is configured to operate the condenser-type heat exchanger and / or the evaporator-type heat exchanger in order to maintain a setpoint temperature in the room.

[0015] According to one embodiment, the system further includes a register configured to allow air renewal in the room.

[0016] According to one embodiment, the system is configured to perform a purging phase, i.e. a renewal of the air contained in the room, after each shutdown phase of the desiccant drying system and / or the condensation drying system. Brief description of the drawings

[0017] Embodiments of the invention will be described below with reference to the drawings, briefly described below:

[0018] [Fig-1] represents a product drying system according to one embodiment.

[0019] [Fig.2] represents steps implemented by the product drying system according to a particular embodiment.

[0020] [Fig.3] represents a condensation drying system.

[0021] [Fig.4] represents a desiccation drying system.

[0022] In the drawings, identical references designate identical or similar objects. DETAILED DESCRIPTION

[0023] Fig. 1 is a schematic general view of a product drying system 1 (not shown) according to one embodiment.

[0024] System 1 comprises a room 10. The room 10 has a closed or partially closed enclosure 11. The enclosure 11 must be insulated with suitable materials to prevent heat transfer and thermal bridging. Thus, the enclosure 11 could, for example, be a refrigerated container.

[0025] Advantageously, the products to be dried can be plant products (for example prunes, seaweed, peppers, etc.), seeds, legumes, protein products such as meat, bones or fish, ... The products to be dried can be placed on trays, directly in room 10, or in a receptacle 2 provided for this purpose.

[0026] System 1 comprises a condensation drying system 20 including a fan 21, a condenser-type heat exchanger 22, an evaporator-type heat exchanger 23, a heating element (not shown), an expansion valve 24, a compressor 25 and a condensate tank (not shown). The condensation drying system 20 is illustrated more particularly in [Fig. 3].

[0027] The operation of such a system is known.

[0028] The condenser-type heat exchanger can be used to increase the temperature in room 10, thus enabling the drying of the products, while the evaporator-type heat exchanger allows the temperature in the room to decrease. Therefore, the use of such a condensation drying system 20 is particularly advantageous since it allows, on the one hand, the drying of the products, and on the other hand, the regulation of the temperature in the enclosure 11. Furthermore, such a system is energy-efficient, so the energy required for drying the products can be reduced compared to existing systems that use gas.

[0029] The system 1 further comprises a desiccant drying system 30, more particularly illustrated in [Fig. 4]. The desiccant drying system 30 comprises a fan 31, a desiccant wheel 32, a heating element 33, and two dampers 34 for regulating the air intake and exhaust in the desiccant drying system 30.

[0030] The desiccant drying systems 30 and condensation drying systems 20 can be placed inside the enclosure of the room 10. In another embodiment, the systems 20, 30 can be placed outside the enclosure 11 of the room 10. In this embodiment, ducts can connect said systems 20, 30 to the room in order to allow the treatment of the air contained in the room.

[0031] The system 1 may also include a plurality of sensors 40, including in particular at least one temperature sensor, one humidity sensor for measuring the humidity level in the room, and / or a temperature and humidity sensor. The sensors 40 are advantageously located inside the room 10. The plurality of sensors 40 may further include at least one temperature sensor located outside the room.

[0032] The system 1 may further include two registers 50, allowing outside air to enter the room 10, if necessary, and allowing the air contained in the room 10 to exit the room 10. In one embodiment, at least one register 50 may be opened if the outside air humidity is lower than a setpoint humidity level to be achieved in the room 10, as described in more detail below. Thus, a temperature and / or humidity sensor may also be placed outside the enclosure 11 in order to record the temperature and / or humidity data of the air. outside. In another embodiment, at least one register 50 can be opened in order to renew the air present in the room 50 during the purging phase which is described in more detail below.

[0033] System 1 may also include a ventilation system 60 comprising at least one fan, the role of which is to circulate the air in the room 10.

[0034] The system 1 may further include a controller (not shown), receiving the data measured by the sensors. In one embodiment, the controller may be configured to adjust the parameters of the condensation drying system 20 and the desiccation drying system 30. In particular, the controller may be configured to adjust certain system parameters, for example, the operating time of said systems 20, 30, the operating speed of the respective fans of said systems 20, 30, a desired temperature inside the enclosure 11 by influencing, for example, the expected air temperature and humidity at the outlet of the heat exchangers 22, 23, the rotational speed of the fan of the ventilation system 60, the activation / closing of the dampers 50, etc.

[0035] In the following description, when it is indicated that one of the components of system 1 is activated and / or switched off, it is understood that the activation / switch-off commands can be implemented automatically by the controller, based for example on data collected by sensors 40, and / or can be implemented manually by an operator, possibly via the controller.

[0036] During the drying process, the system 1 comprises four main operating phases once the products to be dried are placed in room 10.

[0037] These phases are illustrated in [Fig.2].

[0038] The first PI phase is a heating phase of the interior of the room 10 to a setpoint temperature. The temperature can be set in advance. The setpoint temperature can vary depending on the type of products to be dried. By way of non-limiting example, the setpoint temperature can be between 30°C and 80°C, advantageously between 30°C and 50°C.

[0039] The objective of the PI phase is to prepare the products for drying. Bringing the chamber up to temperature may include lowering the temperature measured in the room to the setpoint temperature if said temperature measured in the room is too high, or may include raising the temperature in the room if said temperature measured is too low.

[0040] During this temperature-setting phase, the condensation drying system 20 and the desiccation drying system 30 can be activated until the desired temperature is reached.

[0041] During the first PI phase, the evaporator-type heat exchanger 22 can also be activated to prevent the temperature from exceeding the desired temperature. The condenser-type heat exchanger 22 can also be activated when the data collected by the temperature sensor located inside room 10 indicates that the temperature inside room 10 is lower than the desired temperature.

[0042] Also, during the first PI phase, the ventilation system 60 can be activated to allow air mixing in the room 10, thus ensuring that the measured temperature is homogeneous in the enclosure 11 of the room 10.

[0043] This first phase may be optional.

[0044] A second phase P2 of dehumidification of the air contained in the enclosure Phase 11 of room 10 is then implemented, during which the condensation drying system 20 is activated until the desired humidity level is reached in room 10. Advantageously, the dehumidification phase is implemented until the humidity level in room 10 reaches 30%. This value is given for guidance only and is not limiting. The desired humidity level can be adjusted according to the products to be dried, or according to other parameters such as the stage of maturity of the products, their thickness, or their heat and / or moisture transfer capacity. The humidity level in room 10 can be monitored using sensors 40.

[0045] During the dehumidification phase P2, the desiccation system 30 can also be used in conjunction with the dehumidification system 20.

[0046] The dehumidification phase P2 is itself divided into operating periods, during which the condensation drying system 20 (or the desiccation system) is activated, and homogenization periods, during which the condensation drying system 20 (and the desiccation system 30, if applicable) is switched off. During the operating periods, the moisture contained at least on the surface of the products to be dried is absorbed by the airflow, thus drying the products. During the homogenization periods, the moisture contained within the products to be dried rises naturally to the surface. The homogenization periods therefore prevent any crusting of the product surface. They also reduce the energy costs required for drying since the condensation drying system 20 is switched off, while simulating accelerated natural day-night drying cycles.

[0047] The shutdown of the condensation drying systems 20 (and / or desiccation systems 30 where applicable) during the dehumidification phase, i.e. the homogenization periods, can be decided according to several embodiments.

[0048] In a first embodiment, the homogenization periods can be scheduled. For example, at each predefined time interval the system of Condensation drying can be stopped. For example, a homogenization period can be scheduled after an operating period of between 1 and 6 hours. The duration of the homogenization period can also be predefined and can last from a few minutes to several hours. Schedules can be modified according to the operator's needs, who can adjust the duration and operating parameters of the running and homogenization periods.

[0049] In a second embodiment, the homogenization and operating periods can be operated automatically, in particular thanks to the data measured by the temperature and / or humidity sensors present in the enclosure 11. This data can be sent to the controller which can then decide to operate an operating period, during which the condensation drying system 20 and / or desiccation system 30 is or are running, or to operate a homogenization period, by stopping the condensation drying system 20 (and / or the desiccation system 30 where applicable).

[0050] In particular, a curve showing the evolution of temperature and / or humidity in room 10 can be obtained using the sensors. The controller can then decide, based on the data from these curves, to switch from an operating period to a homogenization period and vice versa. For example, during a homogenization period, the controller can decide to switch to the operating period when the humidity curve rises until it reaches a plateau.

[0051] An alternative embodiment includes placing a first humidity sensor measuring the humidity of the air before the air comes into contact with the product and a second humidity sensor at the outlet of the condensation drying system 20. During an operating period, when the difference in humidity between the incoming and outgoing air is less than or equal to a predefined threshold, for example when the difference is between 1 and 30g of water per m3, the controller can decide to switch from the operating period to the homogenization period.Indeed, when the difference in humidity measured by the first and second humidity sensors is less than or equal to the predefined threshold, it means that the products are dry on the surface, and that it is time to carry out a homogenization period allowing the moisture contained in the center of the products to rise to the surface where it can be removed during a subsequent operating period.

[0052] Advantageously, when it is determined that there is a ceiling in the decline of the humidity curve, that is to say when the humidity curve no longer falls, a period of homogenization can be carried out.

[0053] It is understood that the reading and use of the data collected by the sensors as described above can also be carried out by the operator who can decide, based on the data, to operate a period of operation and / or homogenization.

[0054] The dehumidification phase P2 can include a plurality of operating and homogenization periods.

[0055] In one embodiment, during the homogenization periods, the fan of the desiccant drying system 30 can operate, in order to create air mixing in the room 10. This can allow for faster homogenization of the temperature and humidity in the room 10.

[0056] Similarly, the evaporator-type heat exchanger can also be switched on during operating and / or homogenization periods if the temperature inside enclosure 11 exceeds a predefined threshold.

[0057] Also, the ventilation system 60 can be activated during the second phase, and the dampers 50 can be opened to allow for air renewal and mixing in the room 10. This enables more effective dehumidification. Furthermore, the dampers 50 can be opened if the air outside the enclosure has a relative humidity percentage less than or equal to the desired humidity level in the room 11 at the end of phase 2. Thus, if the target humidity level in the room is 30% and the outside air has a relative humidity below 30%, at least one damper 50 can be opened. This allows, on the one hand, to reach the desired humidity level in the room more quickly and, on the other hand, to reduce energy costs since the humidity of the air in the enclosure will naturally decrease thanks to the mixing of outside air with a lower humidity than that of the air initially contained in the enclosure.

[0058] Once the desired humidity level is reached in room 10, a third drying phase P3 can be implemented. During this drying phase, the desiccation system is activated. The desiccation system 30 dehumidifies and heats the air in room 10 according to a variable humidity level. This variable humidity level can be predefined according to the needs of the product being dried. For example, a prune can be considered dry if it contains less than 30% water, or 12% for a chili pepper.

[0059] Advantageously, the desiccation drying phase is carried out when a target humidity level in the room is too low to be easily achieved by the condensation drying device. The target humidity level during the desiccation drying phase can be between 0% and the desired humidity level at the end of the dehumidification phase. Thus, in the non-limiting example Given that, the drying phase by desiccation can be carried out when the humidity to be reached in room 10 is between 0% and 29%.

[0060] Advantageously, the humidity to be achieved during the drying phase by desiccation is lower than the humidity to be achieved during the drying phase by condensation.

[0061] Advantageously, the drying phase by desiccation is carried out until the humidity in room 10 is less than 5% (value given as a non-limiting example), without rising above it, thus meaning that the products are dry.

[0062] During the desiccation phase, operating periods, during which the desiccant wheel of the desiccant system is in operation, and homogenization periods, during which the desiccant wheel of the desiccant system is switched off, may be carried out. The operating and homogenization periods may be carried out as described with reference to the condensation drying phase. The P3 desiccation phase may include a plurality of operating and homogenization periods.

[0063] Also, during the homogenization periods, the fan of the desiccating system can remain activated in order to allow the mixing of the air in the room 10. Also, the registers 50 can be activated to renew the air contained in the room 10, as described above with reference to phase P2.

[0064] The evaporator-type heat exchanger can also be switched on during the desiccation drying phase, if the temperature inside room 10 exceeds an authorized threshold.

[0065] The desiccation drying phase can be particularly advantageous since the desiccation system is more efficient than the condensation drying system for drying products. However, it is advantageous to implement the dehumidification phase using the condensation drying system beforehand, since the condensation drying system 20 consumes significantly less energy than the desiccation drying system 30.

[0066] Finally, a P4 purging phase is implemented following each homogenization period. This purging phase notably removes moisture from the room air.

[0067] During the purge phase, the air in room 10 is purged by the fan of the desiccant system 30, which is therefore activated. The damper 50, which allows air to exit room 50, is also activated to renew the air in the room. Advantageously, this phase lasts less than three minutes. The purge phase can also be used to reach a setpoint temperature in the room. Once the setpoint temperature is reached, the purge phase can be closed.

Claims

Demands

1. System (1) for drying food products such as plant-based products, seeds, legumes and / or protein products, the system comprising: - a room (10) including an enclosure (11), in which the enclosure (11) is advantageously thermally insulated, the enclosure (11) being intended to receive the products to be dried, the system (1) further comprising: - a ventilation system (60) allowing for mixing the air present in the room (10), - a condensation drying system (20) comprising a condenser-type heat exchanger (22), an evaporator-type heat exchanger (23), an expansion valve (24), a compressor (25) and at least one fan (21), in which the condensation drying system (20) is configured to capture the humidity from the air contained in the room (10) and condense said humidity into liquid water droplets, thus allowing the products to be dried,- a desiccant drying system (30) comprising a desiccant wheel (32), a heating element (33) and at least one fan (31), said desiccant drying device (3) being configured to dry the products, characterized in that the system (1) is configured to operate a condensation drying phase during which said system is configured to implement, iteratively until a first condition is met, an activation of the condensation drying system (20) and a deactivation of the condensation drying system (20), and in that once the first condition is met, the system (1) is configured to operate a desiccant drying phase during which said system is configured to implement, iteratively until a second condition is met, an activation of the desiccant drying system (30) and a deactivation of the desiccant drying system (30).

2. System (1) for drying products according to claim 1, wherein the first condition is a first humidity threshold to be reached in the room, for example a humidity threshold of 30%.

3. System (1) for drying products according to any one of claims 1 or 2, wherein the second condition is a second humidity threshold to be reached in the room, for example a humidity threshold of less than 5%.

4. System (1) for drying products according to claims 2 and 3, wherein the second humidity threshold is lower than the first humidity threshold.

5. Product drying system (1) according to any one of the preceding claims, wherein the system (1) is configured to operate, prior to the activation of the condensation drying system (20), a temperature increase inside the room, said temperature increase being obtained by the activation of the desiccation drying system (30) and the ventilation system (60) of the room or of the condenser-type heat exchanger.

6. Product drying system (1) according to any one of the preceding claims, wherein during the condensation drying and / or desiccation drying phases, the system is configured to actuate the condenser-type heat exchanger (22) and / or the evaporator-type heat exchanger (23) in order to maintain a setpoint temperature in the room.

7. Product drying system (1) according to any one of the preceding claims, further comprising a damper (50) configured to permit air renewal in the room.

8. Product drying system (1) according to any one of the preceding claims, wherein the system is configured to perform a purging phase, i.e. a renewal of the air contained in the room, after each shutdown phase of the desiccation drying system and / or the condensation drying system.

Images