GB2617400A

GB2617400A - Leaf Dewatering system

Info

Publication number: GB2617400A
Application number: GB2205206.2A
Authority: GB
Inventors: Bosch Raymond
Original assignee: Condimentum Ltd
Current assignee: Condimentum Ltd
Priority date: 2022-04-08
Filing date: 2022-04-08
Publication date: 2023-10-11
Anticipated expiration: 2042-04-08
Also published as: GB2617400B; GB202205206D0; GB2617470A; GB202305166D0

Abstract

An apparatus for dewatering mint leaves comprising two belts (31, 41), each comprising a water permeable area (33), and means (36) for driving the belts on support rollers. One belt lies over and is spaced apart from the other, with a dewatering zone between them. In use, when a bed of wet leaves is positioned in the dewatering zone and the belts are driven in the same direction, liquid is driven out of the bed of wet leaves and through the water permeable area. Preferably the water permeable area is a mesh comprising holes that covers all of the first and second belts, wherein the holes in the first and second belts are 3mm and 2mm in size, respectively. Preferably the belts are 2mm apart and move at the same speed, exerting no shearing force on the leaves. Preferably, the support rollers are spring loaded. Preferably an air blower (34) blows air on the belt mesh. A leaf processing method is also claimed, comprising washing a mass of leaves (23), centrifuging, dewatering, air blowing and then milling them. The leaves may be used to make a concentrate with vinegar.

Description

Leaf Dewatering System

Field of the invention

The invention relates to a system for the removal of water from washed leaves, more particularly, mint leaves after they have been subject to an immersive washing process.

Background of the invention

When mint leaves are received from the field it is important to process these leaves within two hours of harvesting. This is done to retain the freshness and the appearance of the leaves.

To do this, typically the leaves are removed from the stems and the leaves washed to remove any foreign matter including soil. After washing, excess water needs to be removed before further processing of the mint.

However, it can be problematic to remove excess water from the mint leaves in the narrow time window available. If the excess water cannot be removed from the leaves in time, the mint crop would not be up to the specification required for further processing into a consumer product, and as such this mint would be discarded, leading to losses.

It is known in the art to use a cam driven knocker belt system to remove excess water from mint leaves. In this process a rotating cam 'knocks' a belt carrying the mint leaves. This in effect shakes the leaf mass removing the excess water.

However, this cam driven knocker belt system does not produce consistent drying results. It should be understood 'drying' refers to removal of water from the leaf mass, but not necessarily taking the leaves to a fully dry state.

In this process, the amount of water retained in the leaf mass is highly dependent on the nature of the leaves being processed. This is because leaves are capable of trapping water in leaf folds and in the spaces between the leaves. So, at least, the size and fragmentation of the leaves leads to variability in the water retained in the leaf mass being processed.

Also, the rate of processing cannot be reliably increased, because as the leaf mass increases, it becomes more difficult to 'knock' water out from the leaf mass. Simply hitting harder and more frequently with the knocker may only serve to damage the equipment with little improvement to the water removed from the leaf mass.

The somewhat aggressive knocking of the cam on the belt in the knocker system leads to wear and tear on the belt. This wear and tear requires maintenance and the frequent replacement of the worn parts, which leads to lost production time and costs.

The knocking process is also very noisy (e.g. > 80 decibels), and so makes it more difficult to process the leaves, and so requires additional health and safety measures.

There remains a need in the art for an improved method of dewatering mint leaves prior to onward processing.

Summary of the invention

In a first aspect of the invention, there is provided an apparatus for dewatering mint leaves comprising: a first and second belt, wherein the first and second belts comprise a water permeable area, support rollers, and means for driving the first and second belts on the support rollers; and wherein the second belt lies over and is spaced apart from the first belt, and the space between the first and second belts defines a dewatering zone; and wherein in use, when a bed of wet leaves is positioned in the dewatering zone and the first and second belts are driven in the same direction, liquid is driven out of the bed of wet leaves and through the water permeable area.

The apparatus of the invention in effect squeezes the mint leaf mass between two water permeable belts, driving water out of the leaf mass and through the belts.

The dewatering apparatus of the invention provides improved dewatering capabilities over the cam driven knocker belt system known in the art. The squeezing action is more controllable than the knocking process and so the desired level of water retention can be better controlled. This means that greater amounts of mint leaves can be processed reliably at one time and/or at a faster rate. The squeezing action of the belts is gentler and so wear and tear on the belts is also reduced and less noise is made, leading to a safer and more pleasant working environment.

In an embodiment, the water permeable area covers substantially all of the first and second belts. Advantageously, the greater the water permeable area the more efficiently the water can be removed from the wet leaves. A portion, window or substantially the whole belt can be a water permeable area.

In an embodiment, the water permeable area is a mesh comprising holes. A mesh is a convenient way to allow water through the belt. However, other ways are also possible such as punctures, slits, slots in the belt, or the belt can be woven/weaved.

In an embodiment, the holes in the mesh are at least 1mm in size. In an embodiment, the holes in the mesh are 0.5 to 10mm in size, optionally 1 to 5mm in size, further optionally 2 to 3mm in size. Advantageously, the holes in the mesh can be arranged to allow water through, but little or no leaf matter. In an embodiment, the mesh comprises square holes in the belt and that the 2 and/or 3mm size holes is the diagonal measurement of the square.

In an embodiment, the holes in the first belt are larger than the holes in the second belt. In an embodiment, the holes in the first belt are 3mm in size and the holes in the second belt are 2mm in size. In an embodiment, the second belt is a solid and the first belt is a mesh. Advantageously, the holes can be arranged to best support the leaf matter and allow water to pass through the mesh. Advantageously, gravity and the increased cross-sectional area of the mesh encourages the water to drop downwards at a greater rate.

In an embodiment, the first and second belts are space 0.1 to 10mm apart, optionally 1 to 5mm apart, further optionally 2mm apart. Advantageously, selecting the gap between the belts can allow efficient removal of water from the leaf matter; if the matter is too thick it may be more difficult to dewater the leaves and/or may require larger compressive force. Advantageously this allows for varying throughputs. In an embodiment, the space between the first and second belts may be adjusted. In an embodiment, the space between the first and second belts may be adjusted by means of compressing compressive springs.

In an embodiment, the first and second belt move at the same relative speed, so that in use no shearing force is exerted on the bed of leaves. In an embodiment, the first and second belt move at a rate of 1 to 10m/min, optionally 3 to 6m/min, and further optionally 4m/min.

Advantageously, the relative speed of the belts can be adjusted so as to generate a shear force on the leaf bed, or to substantially avoid a shearing force which may end up tearing the leaf matter on the belts. Advantageously, the user can adjust these speeds to suit need.

In an embodiment the support rollers are spring loaded, so that in use they apply a compressive force through the rollers on a bed of leaves in the dewatering zone. The rollers provide means to help efficiently drive the belt, and to apply a compressive force to compress water trapped in the leaf matter on the belt.

In an embodiment, the springs are 2-50N/mm, optionally 5-20N/mm and further optionally 6-14N/mm stainless steel springs. In an embodiment, the springs are pre-tightened to around 30-90%, optionally 50-85% and further optionally 70-80% of their maximum compression length.

In an embodiment, the apparatus further comprises an air blower, which is position so that in use it blows air on and/or through the water permeable area. Advantageously, the blower may remove any remaining water from on the top of the leaf bed, which might for example be trapped by surface tension.

In an embodiment, the apparatus further comprises an air blower, which is position so that in use it blows air on and/or through the bed of leaves. Advantageously, the air blower can efficiently blow excess water from the mass of leaves aiding in drying of the 20 leaves.

In an embodiment, the blower is position just after and/or at the end of the belts of the dewatering zone.

In an embodiment, the air blower is positioned above the second belt and/or is positioned below the first belt. This allows air to pass through the belts.

In an embodiment, the air blower is a centrifugal fan. Various blowers are considered within the scope of the invention.

In an embodiment the air exits the air blower through a slot. The slot allows control of the air flow and generates higher pressure flows of air that can better penetrate leaf matter on the belts.

In an embodiment, the air blower blows at a rate of 5 to 20m3/min, optionally 10 to 15m3/min, and further optionally to 13m3/min.

In a further aspect of the invention there is provided use of the apparatus as defined herein to dewater a mass of mint leaves. In a further aspect of the invention there is provided a method of dewatering a mass of mint leaves using the apparatus as defined/described herein.

In an embodiment, the leaves contain no more than 80, 70, 60, 50, 40, 30, 25, 20, 10, or 5% (wash) water.

In a further aspect of the invention there is provided a method comprising the steps of: * picking a mass of leaves and removing plant stems as necessary; * washing the mass of leaves with wash water, and optionally draining them; * passing the mass of leaves through a dewatering apparatus to remove retained wash water; the apparatus comprising two water permeable belts used to drive water from the mass of leaves.

In an embodiment, the method comprises one or more additional steps selected from: * forming the mass of leaves into a bed of leaves for entry into a dewatering apparatus; * determining the relative water content of the mass of leaves before and/or after any of the processing steps; * placing the mass of leaves in a centrifuge to remove wash water; * using an air blower to aid in the removal of wash water; * producing leaves containing no more than 80, 70, 60, 50, 40, 30, 25, 20, 10, or 5% (wash) water; * milling the leaves; optionally milling the leaves to an average size of about 0.1 to lOmm, further optionally to an average size of about 1 to 5mm, and still further optionally to an average size of about 2mm.

In an embodiment, a method disclosed/described herein, used in a dewatering apparatus as defined/described herein.

In an embodiment, the leaves are mint leaves.

In a further aspect of the invention there is provided a method of making a leaf-based concentrate comprising mixing mint leaves as provided by a method disclosed/described herein, and adding one or more food grade ingredients; and optionally maturing the concentrate; further optionally the food grade ingredients may be selected from vinegar, spirit vinegar, and 5% acetic acid and salt.

In a further aspect of the invention there is provided a method of making a food condiment, comprising the addition of one or more ingredients to the leaves as provided by a method disclosed/described herein, or to the concentrate as disclosed/described herein.

In an embodiment, the mint leaves are removed from the stems in the field by mechanical removal.

In an embodiment, the leaves are washed with a process time through the washer to exit of about 60 seconds. In an embodiment, the process is continuous or may be intermittent. In an embodiment, a reciprocation mesh panel is used to force the mint leaves under the wash water. In an embodiment, the water is below or at room temperature.

In an embodiment, 250 to 2,500kg, optionally 500 to 2,000kg, and further optionally between 750 to 1250kg of mint leaves is processed per hour using the apparatus and/or method herein defined/described.

In an embodiment, the mint leaves pass through the dewatering zone within 20, 30 or 60 seconds.

In an embodiment, one or more of the drive motors is controlled by an inverter. In an embodiment, any trimming of the belt speed may be carried out by adjusting the frequency of the inverter (e.g. to match first and second belt speeds). In an embodiment, 50Hz is the typical standard speed. In an embodiment, the inverter frequency may be 35Hz and up to 70Hz, e.g. to decrease or increase the speed from a typical standard. In an embodiment, one belt is at a fixed frequency, e.g. at 50Hz, and the other is inverter controlled to allow speed matching.

In an embodiment, the water content after dewatering in the dewatering zone is determined by: (i) the leaves are weighed after the dewatering step, (ii) the leaves are subject to aggressive physical dewatering (e.g. spinner/centrifuging). The water captured during the aggressive physical dewatering step can be used to determine the water content retained by the leaves after the dewatering step, e.g. the % remaining water content.

In an embodiment, the leaves are milled to smaller fragments e.g. 2mm sized pieces. In an embodiment a 0.100" cutting head may be used to cut the mint leaves into the required size. In an embodiment, the leaves travel on two endless belt conveyors, one horizontal and one inclined to reach the collection hopper (e.g. an Urschel Comitrol processor Model 2100).

In an embodiment, the process from picking to milling takes less than 3 hours, optionally less than 2.5 hrs, further optionally less than 2 hrs.

In an embodiment, the milled leaves and other ingredients are heated and left to age, optionally from 1 to 9 months, further optionally to age for at least 2, 3, 4 or 6 months.

In an embodiment, the other ingredients may include spirit vinegar. In an embodiment, the other ingredients may include spirit vinegar at 5% acetic acid. In an embodiment, the other ingredients may include salt. In an embodiment, the product is 20-70%, optionally 30-60%, and further optionally is 50% fresh mint leaf. In an embodiment, the product is 20-70%, optionally 30-60%, and further optionally is 50% spirit vinegar.

In an embodiment, the milled leaves and other ingredients are cooked. In an embodiment, the milled leaves and other ingredients are heated at between 60-95°C, optionally between 70-90°C, and further optionally at 85°C. In an embodiment, the ingredients are heated for 5-60 minutes, optionally 7-30 minutes, and further optionally 10 minutes. In an embodiment, the ingredients are heated at 85°C for 10 minutes.

In an embodiment, the cooked ingredients are decanted into a storage container. In an embodiment, the cooked ingredients are decanted into a 1 tonne IBC storage container. In an embodiment, the cooked ingredients are matured for 4 months in the container.

In an embodiment, spring loaded brackets keep the first and second belts apart. The 'squeeze force' is in effect created by the mass of leaves passing between the belts at the line running speed (e.g. 1 tonne per hour) being introduced in to the squeezing (dewatering) section, which is kept at the constant separation distance. The effective height of the flow of leaf mass is such that it adds pressure to the spring supported rollers and as such the desired amount of water is removed by the force thereby applied by the springs resistance to compression.

Brief description of the drawings

Figure 1 is a perspective view of an embodiment of the invention.

Figure 2 is an enlargement of the compressive springs shown in the embodiment in Figure 1.

Detailed description of the invention

Figure 1 is a perspective view of an embodiment of the invention (100) comprising an input assembly (10; 11-13), wash assembly (20; 21-25), dewatering assembly (30, 40; 31-36, 41-46), output assembly (50; 51) and waste assembly (60; 61-63).

In use, the input assembly (10) provides leaves to the wash assembly (20) where they are washed. The washed leaves are provided to the dewatering assembly (30, 40), were excess water is removed via two roller belts. The dewatered leaves are provided to the output assembly (50) where they may be further processed. Waste matter and water overflow are captured by the waste/recycling assembly (60).

More specifically, in use the input assembly (10) provides leaves, e.g. mint leaves, to the wash assembly (20) on the input conveyor (11), which is powered by an input motor (12). The leaves exit the input conveyor via input shoes (13), which direct the leaves into the washing basin (23). Leaves in the washing basin (23) are washed. The washing process is controlled by the programmable wash controller (25). Internal water jets (not shown) create a flow movement through the washer body to the exit in conjunction with the reciprocating mesh panel (24).

The washed leaves are directed to the dewatering unit (30,40). The dewatering unit is made up of a first (lower) belt arrangement (40) and a second (upper) belt arrangement (30), these being spaced apart to allow the wet leaves to enter between.

The (second) upper belt arrangement (30) has a dewatering belt (31) made of an upper mesh material (33) laid over spring loaded rollers (not shown). The upper mesh material (33) has holes which are about 2mm in size. The dewatering belt is driven by a top motor (36), specifically a Van der Graff drive roller. A release/belt idler (32) is provided to disengage movement of the second (upper) belt arrangement (30) as necessary.

Similarly, the lower (first) belt arrangement (40) has a dewatering belt (41, concealed in the figure) made of a lower mesh material laid over spring loaded rollers. The lower mesh material (33) has holes which are about 3mm in size. The dewatering belt is driven by a bottom motor (46), specifically a Van der Graff drive roller.

The lower and upper belts are maintained at a user set separation distance, e.g. 2mm apart. The separation may be determined via 14N/mm stainless steel springs set under compression (43), via guide plate and positioning rods attached to a CNC side plate (42).

The compressive force of the springs can likewise be adjusted. So for example the separation distance could be adjusted from 0.1 to 10mm apart. Roller bearing support blocks with covers (44) are also provided via the CNC side plate (42).

An upper blower assembly (34, 35), comprising an air blower (34) and an end cap (35) blows air under the mesh belt (33) to aid in dewatering the leaves. More specifically, a centrifugal fan (at 12.5m3/min air volume) is used to draw ambient temperature air in, and this air is blown through a metal duct with an exit slot along its length. Any water retained on the belt by surface tension is blown onto a catch tray and removed to drain under gravity. There is an air blower and duct fitted to both the upper and lower mesh belt assemblies. As such, a similar arrangement may be provided to the lower blower assembly, with the end cap (45) shown in the figure.

The wet washed leaves provided by the washing assembly (20) are dewater by being passed between the lower and upper belt arrangements (30, 40). Specifically, the wet leaves entering and passing between the two belts are squeezed between the two belts held together by the resilient springs. This compressive/squeezing action drives excess water through the mesh material, and this excess water is directed away from the leaves under gravity. Additionally, water is also blown from the leaves via the terminal blower arrangement (34, 35) as the leaves exit the dewatering unit rollers (30,40).

The output conveyer belt (51) directs the leaves away from the embodiment of the invention, where further processing of the leaves may take place.

Waste/recycling assembly (60) catches any matter not otherwise processed and/or dewatered. These may be fibrous parts, insects, or smaller fragments of leaves etc. The waste conveyor (61) directs the waste into a waste bin (62). Floating matter and/or water overflow is also directed to the waste bin (62) via a water overflow pipe (63).

Water and/or excess leaves may be recycled back into the embodiment of the invention as necessary.

Figure 2 shows an enlargement of the area around the compressive springs shown in the embodiment in Figure 1. The 14N/mm stainless steel springs (43) are compressed via a central compression adjusting screw (47), positioned adjacent and between two position rods (48) on guide plates (49). Also shown are the roller bearing support blocks with covers (44) and CNC side plate (42).

Example

Result A -shows the mint leaf water retention using the 'knocker belt' of the prior art.

Result B -shows the mint leaf water retention with an embodiment of the invention with 14N/mm compression springs fitted (i.e. not coil bound).

Result C -shows the mint leaf water retention with an embodiment of the invention with 6N/mm compression springs fitted (i.e. not coil bound).

Result D -shows mint leaf water retention with coil bound springs replicating maximum compression achievable (with no margin for flexibility on varying leaf bed thicknesses).

The example shows that using an embodiment of the invention with different spring compression loadings, the level of water can be controlled e.g. from 23 to 28%, and where more water is removed from the leaves than when using a 'knocking' system of the prior art. If necessary, water can easily be added if this is needed later.

A B C D

KTIOCker 14Njnim 6N/rnm coil belt springs springs bound wings Water-. tete atm l'en1 %Vet leaf tit al abaaitha Dty Sal (pas4 These test results in the above example have been borne out in production results where closer control of the solids to liquid ratio of the finished product have been achieved, even with a variable mint leaf absorbed water ratio, which can depend on the prevailing weather conditions in the days prior to harvest.

Claims

Claims 1. An apparatus for dewatering mint leaves comprising: a first and second belt, wherein the first and second belts comprise a water permeable area, support rollers, and means for driving the first and second belts on the support rollers; and wherein the second belt lies over and is spaced apart from the first belt, and the space between the first and second belts defines a dewatering zone; and wherein in use, when a bed of wet leaves is positioned in the dewatering zone and the first and second belts are driven in the same direction, liquid is driven out of the bed of wet leaves and through the water permeable area.
2. The apparatus according to claim 1, wherein the water permeable area covers substantially all of the first and second belts.
3. The apparatus according to claim 1 or 2, wherein the water permeable area is a mesh comprising holes.
4. The apparatus according to claim 3, wherein the holes in the mesh are at least 1mm in size.
5. The apparatus according to claim 3 or 4, wherein the holes in the mesh are 0.5 to 10mm in size, optionally 1 to 5mm in size, further optionally 2 to 3mm in size.
6. The apparatus according to any one of claims 3 to 5, wherein the holes in the first belt are larger than the holes in the second belt.
7. The apparatus according to any one of claims 3 to 6, wherein the holes in the first belt are 3mm in size and the holes in the second belt are 2mm in size.
8. The apparatus according to any one of claims 3 to 7, wherein the first and second belts are space 0.1 to 10mm apart, optionally 1 to 5mm apart, further optionally 2mm apart.
9. The apparatus according to any one of the preceding claims, wherein the first and second belt move at the same relative speed, so that in use no shearing force is exerted on the bed of leaves.
10. The apparatus according to any one of the preceding claims, wherein the first and second belt move at a rate of 1 to 10m/min, optionally 3 to 6m/min, and further optionally 4m/min.
11. The apparatus according to any one of the preceding claims, wherein the support rollers are spring loaded, so that in use they apply a compressive force through the rollers on a bed of leaves in the dewatering zone.
12. The apparatus according to any one of the preceding claims, wherein the apparatus further comprises an air blower, which is positioned so that in use it blows air on and/or through the water permeable area.
13. The apparatus according to claim 12, wherein the apparatus further comprises an air blower, which is position so that in use it blows air on and/or through the bed of leaves.
14. The apparatus according to claims 12 to 13, wherein the air blower is positioned above the second belt and/or is positioned below the first belt.
15. The apparatus according to any one of claims 12 to 14, wherein the air blower is a centrifugal fan.
16. The apparatus according to any one of claims 12 to 15, wherein the air exits the air blower through a slot.
17. The apparatus according to any one of claims 12 to 16, wherein the air blower blows at a rate of 5 to 20m3/min, optionally 10 to 15m3/min, and further optionally to 13m3/min.
18. Use of the apparatus as defined in any one of the preceding claims to dewater a mass of mint leaves.
19. A method of dewatering a mass of mint leaves using the apparatus as defined in any one of claims 1 to 17.
20. A leaf processing method comprising the steps of: * picking a mass of leaves and removing plant stems as necessary; * washing the mass of leaves with wash water, and optionally draining them; * passing the mass of leaves through a dewatering apparatus to remove retained wash; water, the apparatus comprising two water permeable belts used to drive water from the mass of leaves.
21. The method according to claim 20, wherein the method comprises one or more additional steps selected from: * forming the mass of leaves into a bed of leaves for entry into a dewatering apparatus; * determining the relative water content of the mass of leaves before and/or after any of the processing steps; * placing the mass of leaves in a centrifuge to remove wash water; * using an air blower to aid in the removal of wash water; * producing leaves containing no more than 80, 70, 60, 50, 40, 30, 25, 20, 10, or 5% wash water; * milling the leaves; optionally milling the leaves to an average size of about 0.1 to 10mm, further optionally to an average size of about 1 to 5mm, and still further optionally to an average size of about 2mm.
22. The method according to claim 20 or 21, wherein the dewatering apparatus is defined in any one of claims 1 to 17.
23. The method according to any one of claims 19 to 22, wherein the leaves are mint leaves.
24. A method of making a leaf-based concentrate comprising mixing mint leaves as provided by the method of any one of claims 19 to 23, and adding one or more food grade ingredients; and optionally maturing the concentrate; optionally the food grade ingredients may be selected from vinegar, spirit vinegar, 5% acetic acid and salt.
25. A method of making a food condiment, comprising the addition of one or more ingredients to the leaves as provided by anyone of claims 19 to 23, or to the concentrate as provided according to claim 24.