NL2007281C2 - Irrigation unit and irrigation system comprising such an irrigation unit. - Google Patents

Description

Irrigation unit and irrigation system comprising such an irrigation unit 5 Technical field

The present invention relates to an irrigation unit comprising a water feed, at least one fertilizer feed, an acid feed and a fertilizer mixture outlet, wherein the fertilizer mixture outlet is in fluid communication with the water feed, the at least one fertilizer feed and the acid feed to output a fertilizer mixture via the fertilizer mixture outlet. The 10 invention further relates to an irrigation system comprising such an irrigation unit.

Background

The function of an irrigation unit used in greenhouses (e.g. made of plastic, glass and/or polycarbonate) as well as in open field tillage is to mix fertilizers with water and 15 feed the fertilizer mixture to plants via a distribution system.

A fertilizer mixture typically comprises water, one or more kinds of fertilizer and an acid. In case more than one fertilizer is used, the fertilizers may be mixed with water separately, i.e. before coming into contact with each other, to prevent mutual reaction between the fertilizers which could create sediment that is harmful to the fertilizing 20 process.

Acid is added to control the pH-value of the fertilizer mixture, i.e. to remove bicarbonates and the like present in the water.

The irrigation unit draws water from a water source, e.g. a basin which is filled with (filtered) water from a well, lake, collected rainwater or other water source, but 25 which still may comprise bicarbonates. The fertilizers are added to the mixture by drawing them from fertilizer tanks. The mixed mixture may be filtered to remove impurities that might be introduced when using bad fertilizers.

The greenhouse industry mainly uses two types of irrigation units, namely inline (direct injection) systems and mixing tank irrigation systems.

30 By using inline systems the fertilizers and acid are simply injected into a water conduit.

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Mixing tanks irrigation systems comprise a relatively large mixing tank wherein the water, the fertilizers and acid are inserted and allowed to mix. An example of such a mixing tank irrigation system is the Hortimax FertiMix 300 sold by Bosman B.V.

In mixing tank irrigation systems, the mixing takes place in a mixing tank where 5 the water is injected together with the fertilizers and the acid. In order to ensure that the different components mix, the fluids remain in the tank at least for a predetermined time (for instance a duration time of 30 - 60 seconds).

Such mixing tank irrigation systems have a few disadvantages. The mixing tank itself is a relatively large component, which takes up space and makes transportation of 10 the mixing tank irrigation system relatively expensive. For instance, a typical size of a mixing tank for an irrigation unit with a capacity of 60 m3/h is 750 liters or more.

The outflow of the mixing tank irrigation system is limited due to the necessary duration time of the fluid in the mixing tank.

A further issue is formed by the fact that CO2 is formed when the acid is added to 15 the water and it reacts with bicarbonates (HC03 -) present in the water. Acid is added to reduce the level of bicarbonates and thereby lower the pH level. If the pH level is too high, it is more difficult for the plants to absorbs nutriments. The acid may be nitric acid, phosphoric acid. It has been found that the CO2 negatively influences the reaction between the bicarbonates and the acid, i.e. when the CO2 doesn’t escape, it negatively 20 influences the reaction between the bicarbonates and the acid and it creates a lower pH value than desired which is harmful to the crop. Also, if the CO2 doesn’t escape, the fertilizer mixture is not stable when it leaves the mixing tank irrigation system. As a result, the CO2 level at the crop may be different than the pH value indicated on the controls.

25 All this may result in more irrigation cycles, thus more water and fertilizer, to stabilize pH levels in the soil or substrate.

A too low pH level will affect the growing conditions of the plants when they are irrigated. Therefore, it is advantageous to allow the CO2 to escape after it is has been formed. However, in inline systems the CO2 can’t escape as it is a closed and 30 pressurized system. In mixing tank irrigation systems, the CO2 cannot escape quickly from the mixing tank and a relatively large mixing tank is needed to create a sufficient water buffer.

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Summary

It is an object to provide an irrigation unit which overcomes at least one of the above mentioned disadvantages.

According to an aspect there is provided an irrigation unit comprising a water 5 feed, at least one fertilizer feed, an acid feed and a fertilizer mixture outlet, wherein the fertilizer mixture outlet is in fluid communication with the water feed, the at least one fertilizer feed and the acid feed to output a fertilizer mixture via the fertilizer mixture outlet, characterized in that the irrigation unit comprises a cyclonic unit comprising - a cyclonic fluid inlet which is at least in fluid communication with the water 10 feed and the acid feed, - a fluid outlet via which the fluid can flow towards the fertilizer mixture outlet and - a gas outlet to allow gas to escape from the cyclonic unit.

The cyclonic unit induces a rotational movement of the fluid against a wall of the 15 cyclonic unit which helps CO2 to escape. Due to the rotational movement the fluid is forced against the wall of the cyclonic unit by centrifugal forces, creating a central gas column and thereby a relatively large fluid surface through which the CO2 can escape. Also, due to the rotational movement, the lighter CO2 is forced towards the central axis of the cyclonic unit, which helps the CO2 to escape via the central gas outlet. The term 20 central is used to indicate that the outlet is positioned centrally with respect to the axis of rotation of the fluid.

As a result, the fluid as outputted by the cyclonic unit is a homogeneous fluid, in which no substantial further chemical reactions take place and is therefore stable and of constant quality. Since the CO2 only influences the pH value of the water, a stable pH 25 value corresponds with a full release of the CO2. Tests have proven that a stable pH level is obtained by using the cyclonic unit.

The gas outlet may be a central gas outlet, positioned centrally with respect to the cyclone.

According to an embodiment the cyclonic unit has a substantially vertical 30 cyclonic body axis, wherein the cyclonic fluid inlet is positioned at a level above the fluid outlet.

The body axis of the cyclonic unit is the axis of rotation about which the fluid is induced to rotate. The rotation may be induced by the shape of the cyclonic unit and/or 4 the direction of the cyclonic fluid inlet. The fluid outlet may be located centrally with respect to the body axis of the cyclonic unit, but may also be tangential with respect to the inner wall of the cyclonic unit. Also, the fluid outlet may be located downstream of a buffer tank.

5 According to an embodiment the cyclonic unit is formed to induce a cyclonic fluid flow inside the cyclonic unit creating a central gas column via which gas can escape.

The central gas column has a relatively large interface area with the fluid which facilitates the gas escaping from the fluid. The central gas outlet provides a natural way 10 out for the gas, preferably in an upward direction.

According to an embodiment the central gas outlet is coaxial with the vertical cyclonic body axis.

The central gas outlet may be used to collect the CO2 and possibly distribute the CO2 to the atmosphere of the plants to improve the growing process.

15 According to an embodiment the irrigation unit comprising a buffer tank positioned upstream of the fluid outlet. This ensures a smooth working irrigation unit and prevents pumps provided downstream from running dry.

According to an embodiment the cyclonic unit comprises a cylindrical wall through which the fluid can flow.

20 A cylindrical wall, which may simply be a tube of suitable diameter, is relatively easy to manufacture and transport.

According to an embodiment the cyclonic unit comprises a conical wall through which the fluid can flow, having a first diameter at the level of the cyclonic fluid inlet and a second diameter at the level of the fluid outlet, wherein the first diameter is 25 greater than the second diameter.

The first and second diameters are measured in a radial direction with respect to the cyclonic body axis and the axis of rotation.

In a conical wall the fluid can maintain its rotational movement relatively easy, since the diameter decreases along the height of the cone.

30 Furthermore, it is noted that the height of the cyclonic unit can be relatively low for a conical cyclonic unit compared to a cylindrical cyclonic unit, making the irrigation unit relatively small and easy to transport.

5

According to an embodiment the conical wall is formed as a hollow, truncated conical wall with a cone angle a between the wall and the cyclonic body axis, wherein 8° < a < 45°.

According to an embodiment the cyclonic fluid inlet is tangential with respect to 5 a wall of the cyclonic unit.

This way the fluid entering the cyclonic unit is induced to perform a cyclonic movement, i.e. to flow through the cyclonic unit in a rotational way.

According to an embodiment the cyclonic fluid inlet is at an angle p with respect to the cyclonic body axis, wherein 30° < P < 90°. Angle P may for instance be 60° to 10 ensure a steady cyclonic flow wherein the fluid makes relatively many rotations without losing its rotational velocity.

According to an embodiment the irrigation unit comprises a mixing unit arranged to mix water received via the water feed, fertilizer received via the at least one fertilizer feed, and acid received via the acid feed.

15 The mixing unit mixes the components of the fertilizer mixture. Preferably, in case more than one fertilizers are used, the fertilizers are separately mixed with the water, before being mixed mutually to prevent reaction between the fertilizers. The output of the mixing unit is connected to the cyclonic fluid inlet.

According to an embodiment the cyclonic unit comprises two or more cyclonic 20 fluid inlets positioned along a circumference of the cyclonic unit.

This way a more stable cyclonic flow is ensured. Also, by providing more than one cyclonic fluid inlet, the cyclonic unit may be suitable for use with different capacities.

According to an aspect there is provided an irrigation system for distributing fluid 25 to an agricultural area comprising an irrigation unit according to any one of the preceding claims and distribution conduits arranged to receive fertilizer mixture from the irrigation unit.

The various aspects discussed in this patent can be combined in order to provide additional advantages.

30 6

Description of the drawings

Embodiments will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which: 5 Fig. 1 schematically depicts an irrigation unit according to an embodiment,

Fig.’s 2a - 2e schematically depicts a cyclonic unit according to different embodiments, and

Fig. 3 schematically depicts an irrigation unit according to an alternative embodiment.

10 The figures are only meant for illustrative purposes, and do not serve as restriction of the scope or the protection as laid down by the claims.

Detailed description of embodiments

When preparing a fertilizer mixture of water and one or more fertilizers, the pH 15 level of the fertilizer mixture is an important parameter. Therefore, acid is added to the mixture to reduce the level of bicarbonates by chemical reactions with the acid. As a product of the chemical reactions, CO2 is generated, which negatively influences the progress of the chemical reaction between the bicarbonates and the acids and thereby influences the pH level of the fertilizer mixture and the quality of the fertilizer mixture. 20 According to the embodiments presented here with reference to the Fig.’s 1-3, an irrigation unit is provided in which the CO2 is removed by flowing the fertilizer mixture through a cyclonic unit 100, thereby creating a central gas column via with the CO2 is withdrawn from the fertilizer mixture.

Fig. 1 schematically shows a irrigation unit 1, comprising a mixing unit 2 and a 25 cyclonic unit 100 according to an embodiment.

The mixing unit 2 is connected to a water feed 11, one or more fertilizer feeds 21 (two are shown in the figures) and an acid feed 31, which are connected to a water source 10, one or more fertilizer sources 20 and an acid source 30 respectively.

The water source 10 may be a storage tank comprising (filtered) water, but may 30 also be formed by a connection to the water supply system.

The fertilizer source 20 may be a storage tank comprising fertilizer, such as YaraLiva Calcinit and a NPK fertilizer.

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The acid source 30 may be a storage tank comprising a suitable acid, such as nitric acid or phosphoric acid.

Of course, the irrigation unit 1 may comprise more and other feeds, such as for instance a feed with a caustic fluid. The water feed 11, the fertilizer feeds 2land the 5 acid feed 31 may comprise valves 12, 22, 32 or the like to control the inflow.

The mixing unit 2 is arranged to mix the different components, i.e. water received via the water feed 11, fertilizer received via the at least one fertilizer feed 21, and acid received via the acid feed 31. The irrigation unit 1 comprises a fertilizer mixture outlet 41 via which the fertilizer mixture can be outputted and can flow to a distribution 10 system or the like (not shown). The mixing unit 2 comprises an output 3 connected to a cyclonic unit 100, via which the fertilizer mixture can flow towards the cyclonic unit 100.

According to an alternative (not shown), the mixing unit 2 may be arranged to mix the water and the acid which is provided to the cyclonic unit 100, while the 15 fertilizers are added downstream with respect to the cyclonic unit 100.

A more detailed description of the mixing unit 2 will be provided below with reference to Fig. 3.

Examples of cyclonic units 100 are shown in Fig.’s 2a - 2e. The cyclonic unit 100 may for instance be made of High Density Polyethylene.

20 In general, the cyclonic unit 100 comprises - a cyclonic fluid inlet 101 which is arranged to receive the fluid outputted by the mixing unit 2 via output 3, - a fluid outlet 102 via which the fluid can exit the cyclonic unit 100 and flow towards the fertilizer mixture outlet 41 and 25 - a central gas outlet 103 to allow gas to escape from the cyclonic unit 100.

The cyclonic fluid inlet 101 is at least in fluid communication with the water feed 11 and the acid feed 31, and possible, as shown in the Fig.’s 1 and 3 with the fertilizer feeds 21. Alternatively, the fertilizer may be added downstream of the cyclonic unit 100.

30 The cyclonic unit 100 may be formed such that a cyclonic flow is generated with a central gas column via which gas, such as CO2 can escape, which is shown in Fig. 2a. It is noted that the central gas outlet 103 may simply be formed by providing the cyclonic unit 100 with an open top. A pump or fan (not shown) may be provided to 8 facilitate the removal of gas. The CO2 may be collected using a collector conduit 310 (only shown in Fig. 3 by way of example) for storage and/or for supplying the CO2 to the atmosphere of the plants.

Alternatively, the top of the cyclonic unit 100 may be covered by a lid 311 5 (shown in Fig. 3) or the like with a central opening forming the central gas outlet 103. The collector conduit 310 may be connected to the lid 311 or even enter the cyclonic unit 100 through the central opening of the lid 311 such that one end of the collector conduit 310 is positioned at a suitable height in the cyclonic unit 100 to collect the CO2.

The cyclonic unit 100 may comprise an annular wall 110, 100’, formed as a 10 cylinder or truncated cone, where through the fluid can flow in a cyclonic way. The wall may be substantially rotational symmetric with respect to a cyclonic body axis A, which in use will be substantially vertical.

The cyclonic unit 100 may further comprise a buffer tank 115 near and upstream of the fluid outlet 102. The buffer tank 115 is provided to prevent pumps provided 15 downstream (such as pump 120 described in more detail below) from pumping air instead of fluid. The buffer tank 115 is provided to collect a small amount of fluid to prevent the pump from running dry. Also, the presence of the buffer tank 115 ensures that the system runs smoothly. In the buffer tank 115a horizontal plate may be mounted just above the inlet of the pump, to prevent a swirling motion and swirling 20 inflow of the pump.

The cyclonic fluid inlet 101 may be provided at a level above the fluid outlet 102 such that the fluid will flow under influence of gravity.

Fig.’s 2a and 2b schematically depict a cyclonic unit 100 with a wall 110 formed as a part of a cone. The cone angle a between the wall 110 and the cyclonic body axis 25 A may be any suitable angle, but may preferably be in the range 8° < a < 45°, more preferably 10° < a < 20°, for instance 15°.

The angle a of the wall 110 introduces a tangent force on the fluid creating a horizontal inward pointing force (anti-centrifugal force) and a vertical upwards force that will counteract the gravity. There is a trade-off between the time spent in the cone 30 and centrifugal force. The increase of centrifugal force increases the CO2 removal but the water has to be in the cone long enough to come to the minimal reaction time that was measured during an earlier test with the fertilizers.

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So, it will be understood that the optimal angle a may be different depending on the circumstances, such as the required throughput of the cyclonic unit 100, the chemical composition of the fluid (influencing the reaction time and the amount of CO2) and the maximum allowable dimensions of the cyclonic unit 100.

5 Fig. 2c schematically depicts an alternative embodiment wherein the cyclonic unit 100 comprises a wall 110’which is cylindrical.

A cylindrical embodiment is relatively easy to manufacture and has a small footprint.

The cone shaped embodiment creates a better cyclone motion since the speed of 10 the fluid is maintained due to the cone shape. The natural decrease in speed of the fluid is compensated by a shorter way of travel to complete a rotation inside the tank. This maintains or even decreases the time to complete every rotation which also should create a stronger cyclone motion.

Fig.’s 2d and 2e shows a further embodiment, in which the cyclonic unit 100 15 comprises a plurality of cyclonic fluid inlets lOlpositioned at equally spaced positions along the circumference of the wall 110.

Fig. 2d schematically depicts a top view of the cyclonic unit 100, while Fig. 2e shows a side view. Fig.’s 2d - 2e show an example with three cyclonic fluid inlets 101. This will create an even more stable cyclonic flow inside the cyclonic unit 100.

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The cyclonic fluid inlet 101 may be tangential with respect to the wall 110, 110’ to provide a cyclonic flow inside the wall. The cyclonic fluid inlet 101 may have a central inlet axis B which comprises a tangential component with respect to the cyclonic body axis A.

25 According to the embodiments shown in Fig. 2a and 2c, the central inlet axis B of the cyclonic fluid inlet 101 is at a substantial right angle P with respect to the cyclonic body axis A. According to this embodiment the cyclonic fluid inlet 101 is substantial horizontal.

According to an alternative embodiment shown in Fig. 2b, the central inlet axis 30 B’ is at an angle P with respect to the cyclonic body axis A, wherein 30° < P < 90°, i.e. the central inlet axis B’ comprises a horizontal component which is tangential with respect to the cyclonic body axis and a vertical component which is at angle P with respect to the cyclonic body axis A. The central inlet axis B’ is directed downwardly.

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Angle P may be chosen such that a cyclonic fluid flow is generated inside the cyclonic unit 100 which remains cyclonic between the cyclonic fluid inlet 101 until the fluid outlet 102.

Angle P will influence the amount of time the fluid will spend in the mixing unit 5 100. Choosing angle P close to or equal to 90° gives the fluid a chance to travel more rotations inside since it would maintain its height for a longer time. However, this may result in a disturbed flow as the fluid may hit itself in the back after one rotation. This might create turbulence that can partially destroy the cyclonic motion. To prevent this, angle P may be chosen such that the inflow has high enough vertical velocity 10 component as this creates a better cyclone even though it could create fewer rotations.

Again it will be understood that the optimal angle P may depend on the actual flow parameters, such as the inlet pressure/velocity and flow rate at the cyclonic fluid inlet 101, the dimensions of the mixing unit 100 etc.

15 Fig. 3 shows an embodiment wherein the mixing unit 2 is schematically depicted in more detail. Alternative embodiments of the mixing unit 2 are conceivable and suitable for use in combination with the cyclonic unit 100 as described.

The water feed 11 is connected to a conduit 204 which connects the water feed 11 to the cyclonic fluid inlet 101. Conduit 204 comprises a pump 201.

20 The mixing unit 2 further comprises a feedback conduit system 205 which is connected to the conduit 204 at a position downstream of the pump 201 and upstream of the pump 201 to provide a feedback loop around the pump 201.

The feedback conduit system 205 comprises a valve 203 which makes it possible to close the feedback conduit system 205.

25 The feedback conduit system 205 further comprises a plurality of parallel conduits 205.1, 205.2, 205.3. The one or more fertilizer feeds 21 and the acid feed 31 are each connected to a different one of the plurality of parallel conduits 205.1, 205.2, 205.3. The feeds 21,31 are connected to the plurality of parallel conduits 205.1,205.2, 205.3 via venture devices 202. Of course, alternative connections between the feeds 21, 30 31 and the plurality of parallel conduits 205.1, 205.2, 205.3 are conceivable as well.

By providing a plurality of parallel conduits 205.1, 205.2, 205.3 it is possible to mix the different fertilizers and the acid with the fluid flowing through the feedback conduit system 205 separately, to allow the fertilizers and the acid to mix with the fluid 11 before getting in contact with each other to prevent mutual reactions between the fertilizers and between the fertilizers and the acid.

The irrigation unit may further comprises sensors and measuring units (not shown) to monitor the quality and characteristics of the fertilizer mixture.

5 Fig. 3 further shows a pump 120 provided downstream of the fluid outlet 102.

The cyclonic unit 100 preserves at least some of the flow velocity of the fluid.

However, pump 120 may still be needed to further transport the fertilizer mixture. This pump may be arranged to generate a 4 bar flow.

Alternatively, the mixing unit 2 does not comprise a feedback conduit system, but 10 instead conduit 204 comprises a plurality of in-line feeds to add the fertilizer and the acid directly to conduit 204.

It will also be obvious after the above description and drawings are included to illustrate some embodiments of the invention, and not to limit the scope of protection. Starting from this disclosure, many more embodiments will be evident to a skilled 15 person which are within the scope of protection and the essence of this invention and which are obvious combinations of prior art techniques and the disclosure of this patent.

Claims (13)

An irrigation unit (1) comprising a water supply (11), at least one fertilizer supply (21), an acid supply (31) and a fertilizer mixture outlet (41), wherein the fertilizer mixture outlet (41) is in fluid communication with the water supply (11) ), the at least one fertilizer supply (21) and the acid supply (31) for outputting a fertilizer mixture via the fertilizer mixture output (41), characterized in that the irrigation unit (1) comprises a cyclone unit (100), which comprises 10 a cyclone fluid inlet (101) which is at least in fluid communication with the water inlet (11) and the acid inlet (31), - a fluid outlet (102) via which fluid can flow to the fertilizer mixture outlet (41) and - a gas outlet (103) via which gas can escape from the cyclone unit 15 (100). The irrigation unit (1) according to claim 1, wherein the cyclone unit (100) has a substantially vertical cyclone body axis (A), wherein the cyclone fluid inlet (101) is positioned at a level above the fluid outlet (102). 20 An irrigation unit (1) according to any one of the preceding claims, wherein the cyclone unit (100) is configured to induce a cyclone liquid flow within the cyclone unit (100) whereby a central gas column is created through which gas can escape. 25 The irrigation unit (1) according to any of the preceding claims, wherein the central gas outlet (103) is coaxial with respect to the vertical cyclone body axis (A). Irrigation unit (1) according to one of the preceding claims, comprising a buffer tank (115) which is positioned upstream of the liquid outlet (102). An irrigation unit (1) according to any one of the preceding claims, wherein the cyclone unit (100) comprises a cylindrical wall (110 ") through which the liquid can flow. The irrigation unit (1) according to any of the preceding claims 1-5, wherein the cyclone unit (100) comprises a conical wall (110) through which the liquid can flow, which has a first diameter (D1) at the level of has the cyclone fluid inlet (101) and a second diameter (D2) at the fluid outlet level (102), the first diameter (D1) being larger than the second diameter (D2). The irrigation unit (1) according to claim 7, wherein the conical wall is formed as a hollow, truncated cone wall with a cone angle α between the wall (110) and the cyclone body axis (A), wherein 8 ° <a <45 °. 15 An irrigation unit (1) according to any one of the preceding claims, wherein the cyclone fluid inlet (101) is tangential to a wall (110, 110 ") of the cyclone unit (100). An irrigation unit (1) according to any one of the preceding claims, wherein the cyclone fluid inlet (101) is at an angle P with respect to the cyclone body axis (A), wherein 30 ° <P <90 °. 11. Irrigation unit (1) as claimed in any of the foregoing claims, wherein the irrigation unit (1) comprises a mixing unit (2) suitable for mixing water supplied via the water supply (11), fertilizers supplied via the at least a fertilizer supply (21) and acid which is received via the acid supply (31). 12. Irrigation unit (1) as claimed in any of the foregoing claims, wherein the cyclone unit (100) comprises two or more cyclone liquid inputs which are positioned along a circumference of the cyclone unit (100). An irrigation system for distributing liquid to an agricultural area comprising an irrigation unit according to any of the preceding claims and distribution lines adapted to receive the fertilizer mixture from the irrigation unit. 5