Greenhouse for hydroponics and algae culture in a fluidised bed

Abstract

A greenhouse (1) for hydroponics and algae culture in a fluidised bed has a tank (2) consisting of a U-shaped structure (3) and two heads (7), attached to such structure (3); the latter extends along a longitudinal axis (4) and defines, together with the heads (7), a basin (5) capable of containing a liquid or a fluid bed; the structure (3) is provided with at least one thermoplastic polymer wall (20) having a constant cross-sectional area, when sectioned with cross-sectional planes orthogonal to the aforesaid axis (4); in addition, the thermoplastic polymer wall (20) is a multiwall panel so as to define internal longitudinal passages (21).

Description

[0001] "GREENHOUSE FOR HYDROPONICS AND ALGAE CULTURE IN A FLUIDISED BED"

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This Patent Appl ication claims priority from Italian Patent Application No . 102023000015285 filed on July 20 , 2023 , the entire disclosure of which is incorporated herein by reference .

[0004] TECHNICAL FIELD

[0005] The present invention relates to a greenhouse for hydroponics , on floating buoyant systems or on conveyor belts , and for algae culture in a fluidised bed .

[0006] PRIOR ART

[0007] As is well known, hydroponics consists of out-of-the- soil or soilless cultivation of plants , using a fluidised bed based on water and nutrients , in which the roots of these plants are immersed .

[0008] The liquid is contained in a tank of relatively low height , which is normally constructed from building material and must be provided with appropriate equipment to manage the amount and circulation of water, the amount and supply of nutrients (mineral salts ) and, when necessary, the delivery of air, oxygen, or other gases into the fluidised bed, in a combined manner to ensure optimal balance during cultivation .

[0009] In many solutions , then, greenhouses are provided with a cover, arranged over the tank, and typically defined by a metal frame supporting transparent sheets or panels .

[0010] In the well-known greenhouses described above , the used structures and materials are relatively expensive and require signi ficant installation work, not only to build the tank, but also to assemble the cover and / or to set up the above-mentioned equipment .

[0011] Furthermore , the structures of the well-known greenhouses are relatively rigid in their functions , i . e . they have little flexibility of use , whereas it would be convenient to provide for arrangements so that the same structure can be used for di f ferent cultivation needs .

[0012] Therefore , aim of the present invention is to provide a greenhouse for hydroponics and algae culture in a fluidised bed, which allows these drawbacks to be solved ( and therefore investment to be reduced, greenhouse construction and installation to be simpli fied and / or a versatile solution to be achieved) in a simple and ef fective way .

[0013] Within this general aim, solutions should also be adopted in order to regulate the environmental conditions in a relatively simple way, not only with regard to the fluidised bed contained in the tank, but also with regard to the atmosphere and luminosity to which plants and / or algae are subj ected, in order to achieve a confined environment for their cultivation ( e . g . , to control their atmosphere ) , and / or in order to optimi ze cultivation processes , e . g . with regard to the trans fer of plants during cultivation .

[0014] SUMMARY OF THE INVENTION

[0015] Said aim is achieved by a greenhouse for hydroponics and algae culture in a fluidised bed, as defined in claim 1 .

[0016] The dependent claims define particular embodiments of the invention .

[0017] BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Hereinbelow, for a better understanding of the present invention, preferred embodiments will be described by way of non-limiting example , with reference to the attached drawings , wherein :

[0019] Figure 1 is a perspective showing, in a simpli fied way, a preferred embodiment of the greenhouse for hydroponics and algae culture in a fluidised bed, made according to the teachings of the present invention;

[0020] Figure 2 is a section, along the vertical section plane indicated by the line I I- I I in Figure 1 ;

[0021] Figure 3 is an enlargement of a detail in Figure 2 ;

[0022] Figure 4 shows a detail of Figure 3 , on a further enlarged scale ;

[0023] Figure 5 is a section, on an enlarged scale , along the vertical section plane indicated by the line V-V in Figure 2 ;

[0024] Figures 6 and 7 are enlargements of two details in Figure 5 ;

[0025] Figure 8 is a top plan view of the greenhouse according to the present invention, together with other similar greenhouses arranged so as to define a cultivation flow; and

[0026] Figure 9 is a side view showing the detail of Figure 3 according to a variant of the present invention .

[0027] DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

[0028] In Figure 1 , reference number 1 indicates , as a whole , a greenhouse ( illustrated partially and in a simpli fied way) which comprises a tank 2 which can be used for hydroponics and algae culture in a fluidised bed .

[0029] According to one aspect of the present invention, the tank 2 consists of a structure 3 and two heads 7 : the structure 3 extends along a hori zontal longitudinal axis 4 and is U-shaped so as to define a basin 5 which, in use , contains a fluidised bed or a l iquid for plant or algae culture ; typically, this liquid is defined by water, or a mixture of water and nutrients , such as mineral salts .

[0030] In the case of hydroponics , the plants to be grown are arranged on well-known floating supports 10 , shown schematically, for example defined by boards or conveyor belts , configured so that the roots of the plants are immersed in the liquid of the tank 2 .

[0031] The heads 7 are tightly coupled to opposite axial ends 8 of the structure 3 , in a known manner, not described in detail , so as to axially delimit and close the basin 5 . The heads may be equipped with ducts , passages and / or wiring (not shown) to feed and / or recirculate the liquid contained in the basin 5 , to feed and / or dose nutrients , to deliver a gas ( air, oxygen, carbon dioxide , etc . ) into the liquid, as required by the type of plants / algae that are grown .

[0032] At the same time , the structure 3 has characteri stics such as to essentially perform a structural function, i . e . , to contain the liquid and support the other components . The tank 2 may be unwired in cases where there is no need to supply electricity to the greenhouse 1 .

[0033] With reference to Figure 2 , the heads 7 have respective mouths 12 and 13 ( shown schematically) , one for the entry of water or other liquid into the bas in 5 and the other for the discharge . This configuration, with the mouths 12 and 13 arranged at opposite axial ends of the tank 2 , can be used to have a natural flow of liquid, directed axially, without having to make other arrangements to recirculate the liquid . At the same time , this natural flow can be calibrated to transport the floating supports 10 on the free surface 15 of the liquid at a predefined speed . In particular, as shown in Figures 1 and 8 , the tank 2 , considering a plan view, has a substantially rectangular shape . This rectangular shape is elongated along the axis 4 : in other words , the axial length of the tank 2 is greater than its width ( as measured hori zontally, in a direction orthogonal to the axis 4 ) . In other words , the basin 5 defines a kind of channel along the axis 4 . According to some variants , not shown, the structure 3 could be provided with vertical partitions to divide the basin 5 into multiple longitudinal channels parallel to each other .

[0034] With reference to Figure 5 , according to one aspect of the present invention, the structure 3 comprises at least one thermoplastic polymer wall 20 , which has a constant cross-sectional area, when sectioned with cross-sectional planes orthogonal to the axis 4 ; preferably, the wall 20 is obtained by extrusion of the thermoplastic polymer according to known techniques . For example , it is advantageous to use high-density polyethylene as the polymer for the structure 2 . However, polypropylene , polycarbonate , or other polymers may also be used, provided that they have suf ficient loadbearing structural properties to contain the liquid in the basin 5 with no or negligible deformations .

[0035] In addition, as shown in Figure 7 , the wall 20 is a multiwall panel so as to define internal passages 21 parallel to the axis 4 : in this way, the proposed solution becomes extremely versati le, as well as being relatively light , but nevertheless rigid and strong .

[0036] The internal passages 21 can be used to house one or more ducts 22 , defined by additional components , inserted in the passages 21 . Alternatively, the ducts 22 are defined directly by tubular portions of the walls 20 . As schematically shown in Figure 8 , the ducts 22 start from the heads 7 and can be used to convey water, nutrients , gas , etc . longitudinal ly, according to the needs of the culture . In particular, the ducts 22 are placed in communication with the basin 5 through respective fittings 23 , which are mounted in the structure 3 at predefined points to deliver the substance conveyed within the liquid in the tank 2 . The fittings 23 can have a calibrated fixed cross-section or be equipped with solenoid valves in order to control the amount of substances delivered : i f solenoid valves are present , the internal passages 21 are also used to house the electrical wiring necessary to power these solenoid valves .

[0037] For example , the ducts 22 and the fittings 23 can be used as carbon dioxide bubblers in the fluidised bed, particularly in the case of algae cultivation .

[0038] The ducts 22 may extend over the entire length of the tank 2 or have a shorter length as shown in Figure 8 . Preferably, with reference to this figure , the ducts 22 have di f ferent lengths , for example , to provide a supply of nutrients and / or gas which is di stributed along the tank 2 , based on the growth stage of the cultivated plants ( i . e . , based on the distance travelled by the supports 10 along the axis 4 ) .

[0039] With reference to Figure 5 , in cross-section, the structure 3 is U- shaped and consists of a single continuous wall forming a lower hori zontal base 25 and two lateral sides 26 facing each other . According to some variants , not shown, the base 25 and the sides 26 are defined by respective walls , which are distinct and attached to each other so as to ensure the sealing of the liquid in the basin 5 .

[0040] With reference to Figure 3 , the structure 3 comprises a series of sectors or sections or modules 3a, 3b, etc., which are aligned along the axis 4, are formed by respective walls 20, and are attached to each other so as to ensure the sealing of the liquid in the basin 5, for example through the interposition of junction elements 28. In the specific example shown in Figure 4, the junction elements 28 are additional pieces having a U-shape so that they extend both along the base 25 and along the sides 26, and are preferably snap-fit, i.e., coupled by male / female type couplings, to the axial ends of the sections 3a, 3b, etc. For example, the junction elements 28 are made of the same thermoplastic material as the walls 20. As mentioned above, the type of coupling of the junction elements 28 will be defined so as to ensure the sealing between the modules 3a, 3b, etc.

[0041] The junction elements 28 can be configured to ensure the continuity of the internal passages 21 and the ducts 22 between the various sections 3a, 3b, etc., in a way that is not shown: for this purpose, the junction elements 28 are equipped with through holes coaxial with the internal passages 21. On the other hand, as shown in Figure 4, the junction elements 28 may define a plug to block the internal passages 21 and / or the ducts 22, if necessary.

[0042] Going back to Figure 1, according to a preferred aspect of the present invention, the greenhouse 1 comprises a cover 31 made of thermoplastic polymer, essentially rigid, arranged over at least part of the basin 5 and supported by the structure 3. In particular, as shown in Figure 5, the cover 31 is defined by a thermoplastic material sheet, which has a constant cross-sectional area, when sectioned with cross-sectional planes orthogonal to the axis 4, and is a multiwall panel so as to define further internal passages 33 parallel to the axis 4.

[0043] As for the walls 20 of the structure 3, the sheet defining the cover 31 is also made by extrusion of the thermoplastic polymer. For example, it is advantageous to use polycarbonate or PET as the polymer for the cover 31, but other polymers can also be used. Preferably, the material for the cover 31 is selected so that it is at least partially transparent, i.e., permeable to light. The specific material is selected so as to determine the opacity and / or colour and / or possible UV filtering, depending on the type of plants to be grown, i.e., on the cultivation needs.

[0044] In addition, preferably, the internal passages 33 can be used to house LED lighting devices (not shown) , such as the so-called LED strips, to adjust the underlying luminosity .

[0045] The cover 31 has a lower surface 34 which is concavely curved, with the concavity facing the basin 5, and without any edges; in particular, the lower surface 34 has a barrel shape and extends substantially over the entire width of the basin 5. In greater detail, the lower surface 34 delimits a central part, of constant height, between two opposite side portions 35 of the cover 31. These side portions 35 are parallel to the axis 4 and are arranged, respectively, above or at the upper edges of the sides 26.

[0046] The curved shape of the lower surface 34 should be selected so as to have relatively gentle inclinations and bends in order to avoid localized condensation concentration and thus avoid dripping (on the liquid in the tank 2, on the floating supports 10, and on the cultivated plants) .

[0047] Preferably, during the manufacturing of the cover 31 or at a later stage, the lower surface 34 shall be subjected to an anti-fog treatment, of a type known per se and not described in detail, to limit the formation of condensation. Advantageously, this expedient and an appropriate selection of the slope of the surface 34, in combination with each other, allow the condensation to flow laterally without dripping onto the plants and / or algae cultivated in the basin 5.

[0048] As shown in Figure 6, preferably, near the side portions 35 above the side ends of the basin 5, the cover 31 is equipped with so-called "drop-breaker" elements 36, which allow the drainage of the condensation, which, in use, flows along the surface 34 towards such side ends 35.

[0049] These expedients allow water consumption to be limited compared to the known solutions, as the condensation is fully recovered .

[0050] Preferably, the cover 31 is hinged to the structure 2 around an axis 37, which extends longitudinally on one of the two sides 26. In this way, the cover 31 can rotate between a raised position and a lowered position to open and close the basin 5 at the top (Fig. 5) . In the lowered position, in particular, the two side portions 35 rest on the upper edges of the sides 26 so as to ensure the sealing along these edges (possibly through the interposition of seals, not shown) .

[0051] More preferably, the coupling between the cover 31 and the structure 3 comprises a so-called "virtual hinge", i.e., an intermediate flexible portion of a connecting element 38 (e.g., made of TPV or polythene) which is attached, on one side, to one of the side portions 35 and, on the other side, to one of the sides 26.

[0052] The rotation of the cover 31 can take place either via manually operated mechanisms or via actuator operated mechanisms, which are schematically indicated by reference number 39 in Figure 6, and are at a distance from the axis 37 such as to have an advantageous lever arm allowing easy lifting of the cover 31. If necessary, the actuation could be controlled via an automatic control logic, e.g., to open the basin 5 at the top according to the temperature present in the environment 40 between the lower surface 34 of the cover 31 and the free surface 15 of the liquid (Fig. 5) . In order to avoid the use of electromechanical parts, it is preferable to use a so-called thermal actuator, i.e., an actuator capable of generating a movement in response to a change in temperature, without electrical power. For example, an actuator equipped with bimetallic elements can be provided.

[0053] With reference to Figure 2, preferably, the cover 31 has a length shorter than the length of the structure 3, so that the basin 5 comprises an area 41, which is actually covered and defines the environment 40, and at least one uncovered area 42 at one axial end of the tank 2. In particular, the basin 5 comprises two uncovered areas 42 at the opposite axial ends of the tank 2. The uncovered areas 42 define a loading and / or unloading station, respectively, for placing and / or picking up the floating supports 10 onto / from the free surface 15 of the liquid.

[0054] Preferably, the cover 31, too, similar to the structure 3, comprises a series of sectors or sections or modules, indicated by 31a, 31b, etc., which are axially aligned with each other and attached to each other so as to ensure sealing, for example through the interposition of junction elements 43, not described in detail. According to a preferred aspect of the present invention, as shown in Figure 3, the environment 40 is confined, i.e., it is substantially separated from the atmosphere of the external environment, by means of separating elements 44 supported by the cover 31 at its axial ends. Each element 44 extends downwards from the lower surface 34 to the free surface 15 of the liquid, and across the width of the basin 5 (i.e., from one side 26 to the other) . Therefore, the covered area 41 is longitudinally separated from the uncovered areas 42 by the elements 44. The latter are preferably defined by a network. Alternatively, they can be defined by a sheet or film, or even by a rigid wall, without any holes. The environmental confinement achieved by means of the elements 44 prevents the entry of insects, in particular pests, into the environment 40 to protect the culture. Similarly, it is possible to introduce particular selected insects to aid the culture, or pollinating insects, which are then forced to remain within the environment 40 due to the presence of the elements 44. In these confined environment conditions, the cover 31 is only opened in exceptional cases, for example for maintenance or cleaning of the basin 5.

[0055] The elements 44 should be flexible, retractable, foldable and / or movable, so that the passage between the covered area 41 and the uncovered areas 42 can be opened and closed, in particular for the transfer of the floating supports 10.

[0056] The central part of the cover 31 has a basically barrel shape, as mentioned above and as shown in Figure 5, and has an upper surface 45, which is convexly curved and ends at the two side portions 35. The latter, preferably, protrude upwards from the upper surface 45 and have , on the inside , respective longitudinal channels 46 , as shown in Figure 6 . The latter communicate with the external environment via passages 47 which end near the upper surface 45 to receive and convey rainwater, which may have fallen on the same upper surface 45 . In practice , the channels 46 define respective gutters , which then end at the heads 7 , where rainwater is preferably collected and recycled, in a known manner, not described in detail . According to some variants , not shown, the channels 46 are not provided inside the side portions 35 , but are defined by external connecting areas between the side portions 35 and the upper surface 45 .

[0057] According to the variant in Figure 9 , the cover 31 supports a shading sheet 50 , which is configurable between a retracted condition, in which it is gathered at an axial end of the cover 31 , and an extended condition, in which it covers at least part of the upper surface 45 .

[0058] The extending and retracting of the sheet 50 can take place either via manually operated mechanisms or via actuator operated mechanisms , which are schematically indicated by reference number 51 . For example , the actuation could be controlled via an automatic control , according to particular times of the day and / or to signals emitted by sensors , which are indicative of the underlying luminosity and / or temperature .

[0059] Preferably, the channels 46 described above with reference to Figure 6 are used as guides for retention and flow in the longitudinal direction of the side edges of the sheet 50 , as an alternative or in combination with the gutter function . To meet these needs , the channels 46 and the passages 47 could however have , in cross section, a shape di f ferent from that shown in Figure 6 .

[0060] According to some variants , not shown, the central part of the cover 31 is provided with at least one opening defining a stack 52 , for extracting air from the environment 40 . In particular, the air extraction is adj ustable by varying the width of the aforementioned opening and / or by providing a variable speed fan with remote control . In particular, the stack 52 is arranged in the central part of the cover 31 . This regulates the escape and / or recirculation of air from the environment 40 .

[0061] In addition, the opening defining the stack 52 can be connected to a condenser, in a way that is not shown, in order to recover the water vapour contained in the extracted air and therefore further limit water consumption .

[0062] According to some variants , not shown, the cover 31 is provided with at least one fitting that can be connected to a gas source in order to be able to introduce such a gas into the environment 40 , for example to generate a protective atmosphere .

[0063] Figure 8 shows a possible non-limiting example of use of the present invention, wherein a series of greenhouses 1 are arranged in side-by-side positions : the cultivation of the plants can be planned so as to switch from one greenhouse 1 to another, according to a prede fined cultivation path or flow, such as a zigzag path, by using the uncovered areas 42 as loading and unloading stations , in accordance with the above , and by placing each unloading station so that it is close to a loading station of an adj acent greenhouse 1 . This reduces the time required to transport the floating supports 10 between the various greenhouses 1 in order to optimi ze cultivation times . The advantages o f the greenhouse 1 according to the invention are clear from the foregoing .

[0064] In particular, the structural characteristics claimed for the tank 2 and the cover 31 avoid large and heavy constructions in building material and possible metal frames . In fact , by appropriately selecting the thermoplastic materials to be used to make the structure 3 and the cover 31 , based on common knowledge in the field, it is possible to obtain components which have load-bearing characteristics , are relatively long, can be made in the form of modules and then be assembled together, are however relatively light , and what is more , are relatively cheap, both in terms of construction and in terms of as sembly and installation .

[0065] In particular, the multiwall structure of the walls 20 allows an excellent compromise to be achieved between rigidity and lightness , and at the same time allows internal passages 21 to be provided in order to be able to accommodate pneumatic and / or electrical systems in the same tank 2 , essentially without additional processing . In fact , the only processes required are those to provide the fittings 23 and to couple the modules forming the structure 3 and the cover 31 , so we are talking about relatively limited tasks .

[0066] Furthermore , the arched or barrel configuration of the lower surface 34 , preferably subj ected to an anti- fog treatment , also prevents condensation from dripping on the plants and / or algae during cultivation .

[0067] Moreover, as explained above , the environment 40 is confined by the elements 44 , so its atmosphere , its temperature , and / or the entry of insects can be controlled in a relatively simple way . It is also apparent that the greenhouse 1 can integrate other functions useful for cultivation, such as regulating the luminosity (via LED lighting devices and / or the sheet 50 ) and regulating the composition of the liquid in the tank 2 or the bubbling of a gas ( through the ducts 22 and the fittings 23 ) .

[0068] The length of the tank 2 allows the floating supports 10 to be easily trans ferred from a loading station to an unloading station, i . e . from one uncovered area 42 to another, as i f the greenhouse 1 were a channel , therefore , there is very high flexibility in setting the cultivation flows by arranging a series of greenhouses 1 according to the present invention .

[0069] Other advantages also appear to those skilled in the art from the above .

[0070] Lastly, it is clear that modifications and variations may be made to the greenhouse 1 described above with reference to the accompanying drawings , without however departing from the scope of protection defined by the appended claims .

[0071] In particular, the proportions between the dimensions of the structure 3 and the cover 31 , and / or the internal configuration of the multiwall panels / sheets , may di f fer from what is shown by way of example .

[0072] In addition, the tank 2 could be used without any cover, for some types of cultures , or it could be used in combination with a traditional cover provided with a metal support frame , although in a less advantageous way than described above .

Claims

CLAIMS1.- A greenhouse for hydroponics and algae culture in a fluidised bed, the greenhouse comprises a tank (2) consisting of :- a structure (3) extending along a longitudinal axis (4) and U-shaped so as to define a basin (5) capable of containing a liquid or a fluid bed, and- two heads (7) tightly coupled to opposite axial ends of said structure (3) so as to axially close said basin (5) ; wherein said structure (3) comprises at least one thermoplastic polymer wall (20) having a constant cross- sectional area, when sectioned with cross-sectional planes orthogonal to said longitudinal axis (4) ; said thermoplastic polymer wall (20) being a multiwall panel so as to define internal passages (21) parallel to said longitudinal axis (4) .2.- The greenhouse according to claim 1, wherein said structure (3) comprises a plurality of sections (3a, 3b) , axially aligned with each other, sealingly coupled to each other, and comprising respective thermoplastic polymer multiwall panels with a constant cross-sectional area.3.- The greenhouse according to claim 1 or 2, further comprising a cover (31) , made of thermoplastic polymer, arranged over at least part of said basin (5) and supported by said structure (3) .4.- The greenhouse according to claim 3, wherein said cover (31) is defined by at least one sheet having a constant cross-sectional area, when sectioned with cross-sectional planes orthogonal to said longitudinal axis (4) , and is a multiwall panel so as to define further internal passages (33) parallel to said longitudinal axis (4) .5.- The greenhouse according to any one of claims 3 or 4, wherein said cover (31) has a lower surface (34) , which faces said basin (5) , is concavely curved and extends over the entire width of said basin (5) .6.- The greenhouse according to claim 3 or 4 or 5, wherein said cover (31) is rotatable with respect to said tank (2) about a hinge axis (37) between a raised position and a lowered position, to open and close said basin (5) at the top .7.- The greenhouse according to claim 6, wherein a thermal actuator is provided for rotating said cover (31) about said hinge axis ( 37 ) .8.- The greenhouse according to any one of claims 3 to 7, wherein said cover (31) has a length shorter than the length of said structure (3) , so as to leave uncovered at least one area (42) at an axial end of said basin (5) .9.- The greenhouse according to claim 8, wherein said basin (5) comprises two uncovered areas (42) , at opposite axial ends thereof.10.- The greenhouse according to any one of claims 3 to 9, wherein said cover (31) supports at least one separating element (44) , said element extending downwardly from an axial end of said cover (44) , and along the entire width of said basin (5) , so as to separate the external atmosphere from an internal environment (40) which, in use, is provided between said liquid and a lower surface (34) of said cover (31) .11.- The greenhouse according to any one of claims 3 to 10, wherein said cover (31) comprises:- an upper surface (45) which is convexly curved, and- at least one side portion (35) defining a longitudinal channel (46) arranged in a position so as to collectrainwater falling on said upper surface (31) .12.- The greenhouse according to any one of claims 3 to 11, wherein said cover (31) supports a shading sheet (50) which is configurable between a retracted condition, wherein it is gathered at an axial end of said cover (31) , and an extended condition, wherein it covers at least part of an upper surface (45) of said cover (31) .

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