Device and method for providing anticaking material to a drying chamber of a spray dryer

Abstract

The present invention relates to a device for providing anticaking material to a drying chamber of a spray dryer. It also relates to spray drying apparatus including such a device, and methods for providing anticaking material to a drying chamber of a spray dryer.

Description

[0001] Title of Invention

[0002] Device and method for providing anticaking material to a drying chamber of a spray dryer

[0003] Field of Invention

[0004] The present invention relates to a device for providing anticaking material to a drying chamber of a spray dryer. It also relates to spray drying apparatus including such a device, and methods for providing anticaking material to a drying chamber of a spray dryer.

[0005] Background of Invention

[0006] Spray drying apparatus is used in industrial processes to form dry powders or granules from a liquid or slurry. The process typically involves passing a liquid feed to be dried to one or more nozzles or a rotating disc, where the liquid is atomized into fine droplets. The droplets are then dried in a drying chamber by contact with a stream of hot gas, for example air. The hot gas causes moisture to evaporate, and the dried powder particles or granules can be collected.

[0007] Spray drying technology is applied in a variety of industrial processes, including food production, pharmaceutical production and chemical production. One example is the production of so-called "glue-type" polymers, for example ethylenevinyl acetate (EVA), vinyl acetate ethylene (VAE) and polyvinyl acetate (PVAc). Spray drying of these polymers, as well as other products, can be challenging because the product tends to stick or deposit on the inside wall of the drying chamber. To reduce the extent to which this occurs, anticaking material can be added during the spray drying process. These anticaking materials can act as barrier between particles to be dried, preventing them from aggregating, and thereby reducing or preventing deposits on the walls of the drying chamber and improving the quality of the dried product.

[0008] Conventional systems typically have an inlet for anticaking material positioned at the top or roof of the drying chamber. The anticaking material can fall through the drying chamber, contacting the particles to be dried, and thereby re- duce the aggregation of the powders or particles. These systems have been found to give acceptable results in some circumstances, but for some products there is a need to further reduce the extent of aggregation.

[0009] US2014 / 0237847 discloses a process for producing dispersion powders by means of spray drying of aqueous polymer dispersions and addition of antiblocking agents in a rotary atomization dryer. Antiblocking agent is conveyed by means of compressed air into an annular gap above an upper edge of the atomizer disk of the rotary atomizer. Whilst this can provide improved results in some circumstances, there is a need for a further alternative or improved system, for example a system with increased operational flexibility and / or the opportunity to retrofit into existing spray drying apparatus.

[0010] The present invention has been made from a consideration of this.

[0011] Summary of Invention

[0012] Thus, according to a first aspect of the present invention there is provided a device for dispensing anticaking material into a drying chamber of a spray dryer, the device comprising:

[0013] an anticaking material feed pipe, the anticaking material feed pipe having an inlet for anticaking material at a first end and an outlet for anticaking material at a second end, optionally a deflector, preferably a moveable deflector, is connected to the outlet,

[0014] a device body, the anticaking material feed pipe being connected to the device body, the device body comprising a connector for connecting the device body to the spray dryer;

[0015] the device being configured so that when the device body is connected to the spray dryer, the outlet or deflector where present is arranged to dispense anticaking material in close proximity to an atomisation cloud.

[0016] Compared to conventional systems in which the anticaking material is introduced at the top or the roof of the drying chamber, the device of the invention allows anticaking material to be introduced in close proximity to the atomization cloud in the spray dryer. As a result, improved anticaking properties can be achieved since the contact of anticaking material with the particles within the atomisation cloud is improved. As a result, fewer deposits on the wall of the spray drying chamber occur, resulting in an improved dried product. The improved product can, for example, be seen by measuring the ash content of the product, or by determining product flowability, with a high flowability showing better anticaking properties, or by determining bulk density, with a higher bulk density reflecting a good product. Delivering anticaking material with the device of the invention also results in a more robust product with a more homogeneous distribution of anticaking material in the dried material, compared with conventional systems. Delivery of anticaking material in close proximity to the atomisation cloud enables good dispersion of the anticaking material within the cloud. As a result, the anticaking material is distributed more evenly in the dried product. Thereby, the invention also enables good mechanical binding of the anticaking material to the product, thereby reducing the risk of separation during onward transport of the product, further contributing to an improved quality of dried product.

[0017] Compared with apparatus such as that shown in US2014 / 0237847, the present invention including a device body enables a system which can be retrofitted into existing spray dryer apparatus. Thus, improved spray dried products can be obtained from existing spray dryers.

[0018] According to the present invention the outlet or deflector where present is arranged to dispense anticaking material in close proximity to an atomisation cloud. The proximity can be determined by measuring the shortest straight-line distance between the centre of the outlet where the anticaking material is dispensed and the edge of the atomization cloud. Where a deflector is present at the outlet, the distance can be determined by measuring the shortest straight-line distance between the centre of the opening of the deflector where the anticaking material is dispensed and an edge of the atomization cloud.

[0019] Close proximity will generally be understood to mean that the shortest straight-line distance is 750 mm or less, preferably 600 mm or less, more preferably 500 mm or less. In some embodiments that distance will be even lower, for example 400 mm or less, 300 mm or less, 250 mm or less, or 200 mm or less.

[0020] Dispensing of the anticaking material in close proximity to the atomisation cloud will in general be achieved by having the outlet or deflector where present positioned near to the outlet for atomized feed, whether this be via an atomizer wheel or a nozzle. Thus, preferably, the outlet or deflector where present is arranged to dispense anticaking material in close proximity to a central vertical axis of the atomiser housing and / or central vertical axis of the spray drying chamber. In this way, the horizontal distance between the centre of the outlet or deflector where present and the central vertical axis of the atomiser housing and / or spray drying chamber may be 750 mm or less, preferably 600 mm or less, more preferably 500 mm or less. In some embodiments that distance may be even lower, for example 400 mm or less, 300 mm or less, 250 mm or less, or 200 mm or less. The distance may be in the range of 150 - 400 mm, such as in the range of 200 - 300 mm.

[0021] In some embodiments the atomisation cloud will be symmetrical, meaning the central vertical axis of the atomisation cloud will be an axis of symmetry. The central vertical axis of the atomisation cloud may coincide with the central vertical axis of the atomiser, which will typically coincide with the vertical centreline of the drying chamber. Thus, the aforementioned distances may apply between the central vertical axis of the atomisation cloud and the centre of the outlet or deflector where present. This will be particularly relevant for apparatus with an atomizer wheel.

[0022] In some embodiments, the device comprises a plurality of anticaking material feed pipes, each having an inlet for anticaking material at a first end and an outlet for anticaking material at a second end, each anticaking material feed pipe being connected to the device body. The number of feed pipes may be selected according to the requirements of the system, for example the size of the spray dryer apparatus and / or the requirements of the material being dried. In some embodiments there may be two or more feed pipes. In some embodiments, there may be three or more feed pipes. In some embodiments there may be four or more feed pipes. In some embodiments there may be five or more feed pipes. In some embodiments there may be six or more feed pipes. In some embodiments there may be 2 or 4 - 12 feed pipes, or 2 or 4 - 10 feed pipes or 2 or 4 - 8 feed pipes. A plurality of feed pipes can allow introduction of anticaking material at multiple locations, giving a good distribution in the atomisation cloud.

[0023] Where there is more than one feed pipe, the feed pipes may be distributed on the device body in any suitable way. Preferably the feed pipes are distributed with an essentially equal separation between each pair of neighbouring feed pipes. In some embodiments the feed pipes may have a symmetrical distribution on the device body. This may assist with even distribution of the anticaking material.

[0024] In some embodiments, one feed pipe, more than one of the feed pipes or all of the feed pipes have a deflector connected to the respective feed pipe outlet. The presence of a deflector on one or more of the feed pipes can result in an improved apparatus. For example, the deflector can result in an increased optimisation of the point of dispensation compared systems without a deflector. Further, it will be understood that some anticaking materials can be abrasive, which can cause premature wear if they repeatedly come into contact with parts of the spray drying apparatus, such as the atomiser wheel. One or more deflectors can reduce or even eliminate the wear, prolonging the life of the spray drying equipment.

[0025] Preferably one, more than one or all of the deflectors are moveable deflectors. This can result in further improved optimisation. For example, the deflectors could be positioned according to the material that is to be spray dried and / or the selected anticaking material. Thus, the same device for dispensing anticaking material into a drying chamber of a spray dryer can be used for different spray dried materials. The deflectors could also be moved in real time i.e. the spray drying process could be monitored and if the monitoring reveals that deposits are occurring or too many deposits are occurring the deflectors could be moved as appropriate to reduce or avoid this.

[0026] Where there is more than one feed pipe, preferably the device is configured to allow the device body to be connected to the spray dryer such that all the outlets or deflectors where present are arranged to dispense anticaking material in close proximity to an atomisation cloud. It will be understood that the reference to close proximity here can be interpreted as discussed above. Whilst the proximity need not be the same for all feed pipes, preferably the distance to the atomisation cloud from the outlet or deflector where present for each feed pipe is the same. The horizontal distance to the central vertical axis of the atomiser housing, spray drying chamber and / or the atomisation cloud may be the same for each feed pipe.

[0027] In some embodiments one, more than one or all the deflectors are movable, in particular rotatable. This may be rotatable about a central axis of the anticaking material feed pipe. Thus, the direction of introduction of anticaking material can be adjusted and / or controlled, allowing for optimisation in the delivery of anticaking material, and the opportunity to reduce wear on the spray drying apparatus by directing the deflector away from the atomiser housing where appropriate.

[0028] In some embodiments, one, more than one or all of the deflectors have a hemispherical portion, there being an opening in each hemispherical portion through which anticaking material can be dispensed. This shape of deflector has been found to give particularly favourable dispensing characteristics.

[0029] In some embodiments one deflector, more than one deflector, preferably all deflectors is / are formed from a material which comprises, consists essentially of, or consists of stainless steel. This has been found to give a good product lifetime even when used with abrasive anticaking materials. This thickness of the material forming the deflector can be selected according to the application and / or the particular stainless steel used. In some embodiments it may be preferable to have a stainless stell thickness in the range of 2 - 6 mm, for example 4 mm.

[0030] As an addition or as an alternative one deflector, more than one deflector, preferably all deflectors may have an abrasion-resistant coating. This has also been found to give a good product lifetime even when used with abrasive anticaking materials.

[0031] One, some, or all of the deflectors may be provided with releasable attachment means for connecting the deflectors to the outlet of the feed pipe such that these deflectors can be released and replaced if worn down by repeated operation or damaged.

[0032] In some embodiments, one, more than one or all the feed pipes have a circular cross section. This has been found to facilitate good delivery of the anticaking material. The feed pipe will preferably comprise cylindrical portions connected by a joint or a bend, such that they can conform to the shape requirements imposed by the atomiser housing of the spray dryer. Such bends or joints should not be considered as excluding the pipe from having a circular cross section.

[0033] Optionally all the feed pipes have the same diameter. The diameter may be selected according to the size of the spray drying apparatus with which the device is to be used and / or according to the anticaking requirements of the material(s) to be spray dried. In some embodiments, the wall thickness of the feed pipes will be essentially constant along the length and may be selected to be the same as the wall thickness of the material from which the deflector(s) is / are constructed.

[0034] In some embodiments the device body comprises an inner housing. The inner housing may be shaped to be complimentary to the shape of the spray dryer with which it is intended to be used. Thus, optionally the inner housing may comprise a conical portion to conform to the atomiser housing of the spray dryer.

[0035] In some embodiments the device body may comprise an outer housing, wherein the outer housing encapsulates at least a portion of one, more than one or all of the anticaking material feed pipes. Optionally the outer housing comprises a conical portion.

[0036] In embodiments in which the device comprises an outer housing, the device may further comprise a cooling air inlet and a cooling air outlet, the cooling air inlet being configured to allow cooling air to be introduced within the outer housing, and the cooling air outlet being configured to allow cooling air to be released from within the outer housing. The cooling air can help to mitigate the impact of heat from the drying air on the feed pipe or pipes and the contents thereof.

[0037] The device for dispensing anticaking material into a drying chamber of a spray dryer may be positionable / configured to be positioned between an atomizer housing of the spray dryer and a gas distributor, for example an annular guide duct of the gas distributor. The device may be positionable so that substantially no drying gas enters the device. The anticaking material feed pipe(s) may be configured to isolate the anticaking material from the drying gas. Thus, the device may be configured so that the anticaking material is not conveyed in the device by drying gas. By not using drying gas to convey the anticaking material greater control of delivery of anticaking material can be achieved.

[0038] In a second aspect of the invention, there is provided a spray drying apparatus, the spray drying apparatus comprising the device for dispensing anticaking material into a drying chamber of a spray dryer according to any embodiment of the first aspect of the invention. A spray dryer in which the device of the first aspect of the invention is used will benefit from the advantages discussed in connection with the first aspect.

[0039] Preferably the device for dispensing anticaking material into a drying chamber of a spray dryer is positioned within an air disperser of the spray dryer. The air disperser provides a suitable cavity into which the device can be positioned, with suitable options for connecting the device to the spray dryer. Thus, the device for dispensing anticaking material into a drying chamber of a spray dryer can be positioned between an atomizer housing of the spray dryer and an annular guide duct of a gas distributor. The device may be positioned so that substantially no drying gas enters the device. The anticaking material feed pipe(s) may be configured to isolate the anticaking material from the drying gas. Thus, the device may be configured so that the anticaking material is not conveyed in the device by drying gas. By not using drying gas to convey the anticaking material greater control of delivery of anticaking material can be achieved.

[0040] In a third aspect of the present invention there is provided a method of providing anticaking material into a drying chamber of a spray dryer using a device according to any embodiment of the first aspect of the invention, the method comprising the steps of:

[0041] i) providing anticaking material to the inlet of the feed pipe or to the in- let of each feed pipe;

[0042] ii) allowing anticaking material to travel through the feed pipe to the outlet, or allowing anticaking material to travel through all the feed pipes to the respective outlets; and

[0043] iii) introducing the anticaking material into the spray drying chamber in close proximity to an atomisation cloud.

[0044] It will be understood that all of the configurations or embodiments discussed above in connection with the first aspect of the invention may be utilised in the method of the third aspect of the invention. Likewise, the spray dryer referenced in the method of the third aspect of the invention can be a spray dryer according to the second aspect of the invention.

[0045] Like the first aspect of the invention, the third aspect references close proximity to an atomisation cloud. The proximity can be determined by measuring the shortest straight-line distance between the centre of the outlet where the anticaking material is dispensed and the edge of the atomization cloud. Where a deflector is present at the outlet, the distance can be determined by measuring the shortest straight-line distance between the centre of the opening of the deflector where the anticaking material is dispensed and an edge of the atomization cloud.

[0046] Close proximity will generally be understood to mean that the shortest straight-line distance is 750 mm or less, preferably 600 mm or less, more preferably 500 mm or less. In some embodiments that distance will be even lower, for example 400 mm or less, 300 mm or less, 250 mm or less, or 200 mm or less.

[0047] Dispensing of the anticaking material in close proximity to the atomisation cloud will in general be achieved by having the outlet or deflector where present positioned near to the outlet for atomized feed, whether this be via an atomizer wheel or a nozzle. Thus, preferably, the outlet or deflector where present is arranged to dispense anticaking material in close proximity to a central vertical axis of the atomiser housing and / or central vertical axis of the spray drying chamber. In this way, the horizontal distance between the centre of the outlet or deflector where present and the central vertical axis of the atomiser housing and / or spray drying chamber may be 750 mm or less, preferably 600 mm or less, more preferably 500 mm or less. In some embodiments that distance may be even lower, for example 400 mm or less, 300 mm or less, 250 mm or less, or 200 mm or less. The distance may be in the range of 150 - 400 mm, such as in the range of 200 - 300 mm.

[0048] The ratio of anticaking material compared to the feed may in some embodiments be within the range of 5 - 25 % (w / w) of the solid particles will be suitable. In some instances, 10 - 20 % anticaking material compared to the feed is desirable, preferably 14 - 15 %, more preferred 15 - 16 %. These percentages are solid / solid particle weight percentages. With the method of the invention such ratios are sufficient to ensure anticaking material be distributed evenly within the particles to be dried and providing robust particles that do not agglomerate upon further handling.

[0049] In some embodiments the atomisation cloud will be symmetrical, meaning the central vertical axis of the atomisation cloud will be an axis of symmetry. The central vertical axis of the atomisation cloud may coincide with the central vertical axis of the atomiser, which will typically coincide with the vertical centreline of the drying chamber. Thus, the aforementioned distances may apply between the central vertical axis of the atomisation cloud and the centre of the outlet or deflector where present. This will be particularly relevant for apparatus with an atomizer wheel.

[0050] Brief Description of Drawings

[0051] Embodiments of the invention will be described in the following detailed description with reference to the drawings in which:

[0052] Figure 1 shows a schematic view of a device according to the invention, Figure 2 shows a larger view of the connector shown in Fig. 1,

[0053] Figure 3 shows a larger view of the outlet and deflector shown in Fig. 1, Figure 4 shows a schematic view of a spray dryer with a device according to the invention,

[0054] Figure 5 shows an illustrative positioning of an anticaking material feed pipe and deflector in relation to a rotary atomizer and the corresponding atomisation cloud,

[0055] Figure 6 shows an illustrative positioning of an anticaking material feed pipe and deflector in relation to a nozzle atomizer and the corresponding atomisation cloud,

[0056] Figure 7 shows a representation of the proximity determination between the atomisation cloud and a deflector, using the embodiment of Fig. 5 as an example.

[0057] Figure 8 is analogous to Fig. 7 but using the embodiment of Fig. 6 as an example.

[0058] Detailed Description of Embodiments

[0059] Referring to Fig. 1, a schematic view of a device 2 according to the invention is shown. In the embodiment shown, the device comprises four anticaking material feed pipes 4, three of which are shown in the figure. Each anticaking material feed pipe has an inlet 6 at an upper portion and an outlet 8 at a lower portion of the feed pipe 4. In the embodiment shown each feed pipe is the same, but it will be understood that where there is more than one feed pipe, they need not necessarily be identical. At the outlet 8 of each feedpipe 6 there is a deflector 10. In the embodiment shown all the deflectors 10 are rotatable.

[0060] In the embodiment shown in Fig. 1, the device body 12 comprises an inner housing 24, the inner housing having a conical portion 26 which conforms with a conical portion of the spray dryer particularly the atomiser housing (not shown in Fig. 1). The feed pipes 4 are distributed equally around the inner housing 24 such that the distance between each pair of neighbouring feed pipes 4 is essentially the same. The feed pipes 4 are in the embodiment shown partially encapsulated by outer housing 32, and particularly conical portion 34 of the outer housing 32. The deflectors 10 protrude beyond the outer housing 32 to enable dispensation of anticaking material into the spray drying chamber. In embodiments without a deflector 10, the outlets 8 will in general protrude beyond the outer housing 32 in an analogous manner to enable dispensation of anticaking material into the spray drying chamber. In the embodiment shown, the device is constructed from stainless steel, with a thickness of approximately 4 mm, in order to withstand the abrasive nature of anticaking materials that are intended to be used. It will be understood that the material thickness can be selected according to the properties of the material used. It will also be understood that stainless steel is provided as an example, but alternative materials may be used in practice, such as alternative alloys, to give the desired properties in terms of functionality, ease and cost of production and so forth. Additionally or alternatively abrasion resistance may be provided by a coating, such as chrome coating. The coating may be selected according to requirements, including extent of abrasion resistance required, compatibility with the material to which the coating is to adhere and so forth.

[0061] The invention is not intended to be limited to specific anticaking materials. Thus, the anticaking materials which can be used are those typically used in the field, including calcium carbonate, silica and the like.

[0062] As can be seen in Fig. 1, the device is provided with a cooling air inlet 28 and a cooling air outlet 30. During operation, cooling air can be provided within the outer housing 32 via the cooling air inlet 28. The cooling air can then travel between the inner housing 24 and the outer housing 32, and ultimately to the cooling air outlet 32. Since the device 2 will in general be positioned near to the drying air passing through the spray dryer, heat from the drying air can be transferred to the device 2 and anticaking material travelling through it. The use of cooling air can help to mitigate the impact of this by circulating cooling air past the anticaking material feed pipes 4.

[0063] In general, the anticaking material feed pipe(s) may be connected to the device body in a fixed manner, such as by welding or other equivalent connection means. In the alternative, the anticaking material feed pipe(s) may be connected to the device body in such a way that enables the positioning of the feed pipe to be adjusted. This could for example be a slider connection which allows the feed pipe to be moved up and down, relative to the atomiser housing. Thus, the proximity to the atomisation cloud of the feed pipe outlet or deflector where present can be ad- justed as required. This may be particularly beneficial in embodiments using a nozzle atomiser, where the depth of the nozzle within the spray drying chamber can be adjusted. It may also be beneficial when a spray dryer apparatus is used for different end products since the positioning of the feed pipe can then be selected according to the requirements of the product.

[0064] In some embodiments the feed pipe(s) may be telescopic, or otherwise length-adjustable, such that expansion or contraction of the feed pipe enables adjustment of the positioning relative to the atomisation cloud.

[0065] The feed pipe(s) may be adjusted independently of each other in situations where different distances are deemed feasible.

[0066] The device 2 may be provided with additional connectors and the like, for example to facilitate lifting of the device into place, and / or release means to allow the device or parts of the device to be moved, or released, for example during cleaning procedures.

[0067] A means of connection 14 between the device 2 and the spray drying apparatus 36 can be seen in Fig. 2. Bolt 50 and nut 52 are used to secure the connection between flange 56 of the device 2 and lip 58 of the atomiser housing 36. One or more washers (not shown) may also be used. Gasket 54 helps to ensure a tight seal. Preferably the gasket 54 is made of rubber.

[0068] Referring to Fig. 3, a larger and expanded view of deflector 10 from Fig. 1 can be seen. The deflector 10 has a hemispherical portion 20 and an opening 22 through which anticaking material can be dispensed. To facilitate connection between the outlet 8 and the deflector 10, a mechanism comprising welding nipple 40, holes 42, a locking ring 44 and a locking plate 46 can used. Whilst such a setup has been found to provide favourable characteristics, it will be understood that alternative connection means may be used. Preferably, the deflector 10 can be removed, for example, unscrewed, from the outlet 8 to allow the deflector 10 to be replaced if it becomes worn or damaged. The deflector shown is made from the same material as the anticaking material feed pipes 4. However, the deflector 10 may be made from a different material. The positioning of the deflector 10, or some or all of the deflectors may be set before a spraying process begins or in the initial phase. The deflector(s) may be provided with a motor or like which can facilitate this and / or enable the deflector 10 to be rotated or otherwise moved or adjusted as required during the course of a spray drying process.

[0069] In general, the feedpipes may be provided with flow restricting means, such as a plug or barrier (not shown), preferably in an adjustable manner which enables the flow of anticaking material through the pipe to be adjusted. In this way, not just the position of delivery of anticaking material can be controlled via the deflector(s), but also the flow rate, or amount of anticaking material delivered via the flow restricting means. In general, 5 - 25 % anticaking material compared to the feed will be suitable. In some instances, 10 - 20 % anticaking material compared to the feed is desirable, preferably 14 - 15 %, more preferred 15 - 16 %. These percentages are solid / solid weight percentages. Typically, the delivery will be controlled by control of anticaking material to the feedpipe, but flow restricting means where provided can supplement this as a means to further control the delivery.

[0070] Referring to Fig. 4, this shows a schematic view of a cross section of a spray drying apparatus 36 with a device 2 according to the invention in position. It will be understood that the view is a simplified representation intended to show the relative positioning between the device 2 and the spray drying apparatus 36 and as such not all details of the spray drying apparatus are shown. For example, the drying chamber of the spray drying apparatus 36 is not shown, and other parts of the atomiser are also not shown in detail. The device 2 for dispensing anticaking material into a drying chamber of a spray dryer is positioned between an atomizer housing of the spray dryer and an annular guide duct 68 of a gas distributor 60. In use, feed to be dried is fed to the atomiser housing, through the atomiser wheel 38, or alternatively an atomiser nozzle (not shown) and into the drying chamber. Drying gas passes from gas distributor 60 and supply duct 62, through annular guide duct 68 via vanes 64, 66 into the drying chamber.

[0071] Anticaking material delivery hose 72 connects the source of the anticaking feed material to each of the anticaking material feed pipes. In this way, anticaking material can be dispensed near to the atomisation cloud, resulting in good dispersion of the anticaking material into the atomisation cloud, and thereby favourable anticaking properties. Whilst the device 2 is suitable for use with the gas distributor shown in Fig. 4, the invention is not intended to be limited to this particular gas distributor. It will be understood that the device of the invention may be used with a range of gas distributors and spray drying apparatuses.

[0072] Referring to Fig. 5, this shows an illustrative positioning of an anticaking material feed pipe 4, and particularly the corresponding deflector 10, with opening 22, in relation to a rotary atomizer with atomiser wheel 38 and the corresponding atomisation cloud 18. Whilst the drying chamber of the spray dryer is not shown, it will be understood that the schematic represents a view within the drying chamber. Anticaking material 16 can be seen being dispensed into atomisation cloud 18. The configuration shown has the deflector 10 pointed away from the atomiser wheel. This can be beneficial when abrasive anticaking materials are used as contact between the anticaking material and the atomiser wheel is minimised, thereby reducing wear via abrasion. Nevertheless, the positioning of the feed pipe 4 and corresponding deflector 10 still facilitates good contact between the particles within the atomisation cloud 18 and the anticaking material 16.

[0073] Whilst Fig. 5 shows an atomiser wheel 38, the principle applies equally to other atomisation means, such as a nozzle. Referring to Fig. 6, this shows an illustrative positioning of an anticaking material feed pipe 4, and particularly the corresponding deflector 10, with opening 22, in relation to an atomizer with atomiser nozzle 48 and the corresponding atomisation cloud 18. Whilst the drying chamber of the spray dryer is not shown, it will be understood that the schematic represents a view within the drying chamber. Anticaking material 16 can be seen being dispensed into atomisation cloud 18. In contrast to Fig. 5, the orientation of the deflector is different. When an atomiser nozzle 48 is used, wear is less of a problem compared with an atomiser wheel and so the deflector 10 can be directed accordingly to give good contact between the anticaking material 16 and the atomisation cloud 18. Where a nozzle atomiser is used in place of a rotary atomiser, the atomisation cloud will generally have a narrower profile. Also, for a nozzle atomiser the nozzle can be moved, meaning the central axis of the atomisation cloud need not align with the central vertical axis of the atomiser housing / the spray drying chamber. In general, rotary atomisers can be considered to give an umbrella-shaped cloud whereas nozzle atomisers will give a cone-shaped cloud. The exact form of the umbrella or cone-shaped cloud will depend on the atomiser. For example, different atomiser nozzles will give different cone angles i.e. a nozzle can be selected to give a small angle (narrow cone) or a large angle (broad cone).

[0074] The dispensing of anticaking material in close proximity to an atomisation cloud is represented in Fig. 7 for a system with an atomiser wheel 38 and in Fig. 8 for a system with an atomiser nozzle 48.

[0075] In Fig. 7, distance A represents the shortest straight-line distance between the centre of the opening 22 of the deflector 10 where the anticaking material is dispensed and the edge of the atomization cloud 18. Distance B represents the horizontal distance between the central vertical axis of the atomiser housing (which is the same as the central vertical axis of the spray drying chamber) and the centre of the opening of the deflector 10. For a rotary atomiser the atomisation cloud will generally be symmetrical around a vertical axis of symmetry that coincides with the central vertical axis of the atomiser housing and the central vertical axis of the spray drying chamber.

[0076] In Fig. 8, distance A represents the shortest straight-line distance between the centre of the opening 22 of the deflector 10 where the anticaking material is dispensed and an edge of the atomization cloud 18. Distance B represents the horizontal distance between the central vertical axis of the atomiser housing (which is the same as the central vertical axis of the spray drying chamber) and the centre of the opening of the deflector 10. As can be seen, for an atomiser nozzle, the atomisation cloud will is not necessarily symmetrical around a vertical axis of symmetry that coincides with the central vertical axis of the atomiser housing and the central vertical axis of the spray drying chamber, although it can be when the nozzle points directly downwards.

[0077] 5 List of Reference Numerals

[0078] 2 - device for dispensing anticaking material into a drying chamber of a spray dryer 4 - anticaking material feed pipe

[0079] 6 - inlet for anticaking material feed pipe

[0080] 8 - outlet for anticaking material

[0081] 10 -deflector

[0082] 12 - device body

[0083] 14 - connector for connecting the device body to the spray dryer

[0084] 16 - anticaking material

[0085] 18 - atomisation cloud

[0086] 20 - hemispherical portion of deflector

[0087] 22 - deflector opening

[0088] 24- inner housing

[0089] 26 - conical portion of inner housing

[0090] 28 - cooling air inlet

[0091] 30 -cooling air outlet

[0092] 32 - outer housing

[0093] 34 - conical portion of outer housing

[0094] 36 - spray drying apparatus

[0095] 38 - atomiser wheel

[0096] 40- welding nipple

[0097] 42 - hole

[0098] 44- locking ring

[0099] 46 - locking plate

[0100] 48 - atomiser nozzle

[0101] 50- bolt

[0102] 52 - nut

[0103] 54 - gasket

[0104] 56 -flange

[0105] 58 - lip

[0106] 60 -gas distributor

[0107] 62 - supply duct

[0108] 64 -guide vanes

[0109] 66 - directional vane

[0110] 68 - annular guide duct

[0111] 70 - top of spray drying chamber

[0112] 72 - anticaking material delivery hose

Claims

C L A I M S1. A device for dispensing anticaking material into a drying chamber of a spray dryer, the device comprising:an anticaking material feed pipe, the anticaking material feed pipe having an inlet for anticaking material at a first end and an outlet for anticaking material at a second end, optionally a deflector, preferably a moveable deflector, is connected to the outlet,a device body, the anticaking material feed pipe being connected to the device body, the device body comprising a connector for connecting the device body to the spray dryer;the device being configured so that when the device body is connected to the spray dryer, the outlet or deflector where present is arranged to dispense anticaking material in close proximity to an atomisation cloud.

2. A device according to claim 1, wherein the device comprises a plurality of anticaking material feed pipes, each having an inlet for anticaking material at a first end and an outlet for anticaking material at a second end, each anticaking material feed pipe being connected to the device body.

3. A device according to claim 2, wherein one feed pipe, more than one of the feed pipes or all of the feed pipes have a deflector connected to the respective feed pipe outlet, preferably one, more than one or all of the deflectors are moveable deflectors.

4. A device according to claim 2 or 3, wherein the device is configured to allow the device body to be connected to the spray dryer such that all the outlets or deflectors where present are arranged to dispense anticaking material in close proximity to an atomisation cloud.

5. A device according to any preceding claim, wherein one anticaking material feed pipe, some anticaking material feed pipes or all anticaking material feed pipes have a shortest straight-line distance from the point of dispensing of the anticaking material to the edge of the atomisation cloud of 750 mm or less.

6. A device according to any preceding claim, wherein one anticaking ma-terial feed pipe, some anticaking material feed pipes or all anticaking material feed pipes have a horizontal distance between the centre of the outlet or deflector where present and the central vertical axis of the atomiser housing and / or spray drying chamber of 750 mm or less, preferably in the range of 150 mm to 400 mm.

7. A device according to any preceding claim, wherein one, more than one or all the deflectors are moveable, in particular rotatable.

8. A device according to any preceding claim, wherein one, more than one or all of the deflectors have a hemispherical portion, there being an opening in each hemispherical portion through which anticaking material can be dispensed.

9. A device according to any preceding claim, wherein one deflector, more than one deflector, preferably all deflectors is / are formed from a material which comprises, consists essentially of, or consists of stainless steel; and / or wherein one deflector, more than one deflector, preferably all deflectors have an abrasionresistant coating.

10. A device according to any preceding claim, wherein one, more than one or all the feed pipes have a circular cross section and optionally all the pipes have the same diameter.

11. A device according to any preceding claim, wherein the device body comprises an inner housing, optionally the inner housing comprises a conical portion; and / or wherein the device body comprises an outer housing, wherein the outer housing encapsulates at least a portion of one, more than one or all of the anticaking material feed pipes, optionally the outer housing comprises a conical portion.

12. A device according to claim 11, wherein the device body comprises an outer housing and the device further comprises a cooling air inlet and a cooling air outlet, the cooling air inlet being configured to allow cooling air to be introduced within the outer housing, and the cooling air outlet being configured to allow cooling air to be released from within the outer housing.

13. A spray drying apparatus, the spray drying apparatus comprising the device for dispensing anticaking material into a drying chamber of a spray dryer according to any preceding claim.

14. A spray drying apparatus according to claim 13, wherein the device for dispensing anticaking material into a drying chamber of a spray dryer is positioned between an atomizer housing of the spray dryer and an annular guide duct of a gas distributor.

15. A method of providing anticaking material into a drying chamber of a spray dryer using a device according to any of claims 1 to 12, the method comprising the steps of:i) providing anticaking material to the inlet of the feed pipe or to the inlet of each feed pipe;ii) allowing anticaking material to travel through the feed pipe to the outlet, or allowing anticaking material to travel through all the feed pipes to the respective outlets; andiii) introducing the anticaking material into the spray drying chamber in close proximity to an atomisation cloud.

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