The invention relates to a spray-drying device, in particular to a system for spray- drying a product.

Spray-drying is generally known. In a spray-drying tower, a spray-drying device is provided which is connected to an inlet for the product to be sprayed taken from a store. The product may be milk. Due to the high pressure and heat, the water present in the product can evaporate and the dry product remains. The dry product is collected and transported away and, if desired, undergoes further treatment.

A known spray-drying device can be connected to an injection pipe in the spray-drying tower and comprises a housing with an internal duct accommodated therein. The product is supplied to the internal duct. In the internal duct, a turbulator is arranged in order to impart turbulence to the product. Downstream of the turbulator, the housing comprises an orifice through which the whirling product is passed to the outside, that is to say into the spray-drying tower, and during said expansion through the orifice, part of the evaporation takes place. The spray-drying device with the injection pipe and supply line, together with a pump and an optional store, form a system for spray-drying.

It is known to incorporate a non-return valve in the spray-drying device by means of which the supply of the product to the spray-drying device is blocked if the product supplied via the injection pipe has a pressure which is lower than a certain threshold value. It is also known to produce the housing of the spray-drying device in two parts which are attached to one another by means of a releasable coupling.

A problem of the known spray-drying devices and systems for spray-drying which include such devices is the fact that the supply of product takes place by means of controllable valves upstream of the spray-drying device. Known valves are situated just in front of the injection pipe in the network of pipes, often together with a flange as a result of which it is difficult to remove them in order to carry out maintenance or repair. Access to the valve is difficult. Maintenance leads to a significant loss of production time and also to loss of product which is situated downstream of the valve.

It is an object of the present invention to improve the known device and the known system.

This object is achieved by providing a spray-drying device which is provided with a controllable valve body, which can close off in particular the internal duct of the spray- drying device. The controllable valve body has an open position, in which product is allowed to pass through the internal duct, and a closed position, in which product is blocked, it being possible to switch between positions. Since a controllable valve body is provided, the operator can remotely control the supply of product through the spray- drying device and a control arrangement is obtained which is situated very close to the orifice. The loss of product is significantly reduced and replacement of the controllable valve is greatly simplified, as the spray-drying device is situated at a distal end of an injection pipe which extends into the spray-drying tower and which is readily accessible.

Preferably, the spray-drying device according to the invention comprises a housing which comprises at least two housing parts which are attached to one another by means of a releasable connection, such as a bayonet fastening or a screw connection.

Preferably, the inlet, i.e. the part which can be connected to the injection pipe, forms part of the first housing part and the orifice forms part of the second housing part. This results in a readily separable device, in which in particular the second housing part with the orifice can readily be separated from the first housing part with the inlet and in which replacement of the orifice, for example in the case of blockage, is readily possible.

In an advantageous embodiment, the controllable valve body forms part of the first housing part. This results in a device, in which opening and closing takes place in a housing part which is situated further upstream and the flowing out of the product to be sprayed takes place in the second housing part which is situated further downstream. Blockages may occur in this second housing part and this second housing part can easily be cleaned, in which case the supply of product is closed off just upstream of this removable second housing part.

In one embodiment, the controllable valve body is provided with a pin and a shut-off nipple in which the pin is connected to the shut-off nipple and extends into the second housing part. This has the advantage that the first housing part can easily be extended by extending a sleeve which may form part of the first housing part and is connected to the second housing part, the diameter substantially depending on the diameter of the pin. As a result thereof, a spray device can be obtained which can bridge a relatively large distance between the shut-off nipple and, for example, a movable piston for opening and closing the shut-off nipple, with the piston being situated outside the spray-drying tower and the shut-off nipple being situated near the orifice inside the spray-drying tower. It is particularly advantageous to provide a spray-drying device having a connection for a control line for controlling the valve body and in particular for switching between the open and closed position of said valve body. Via the line, it is for example possible to send a control signal to the valve body and/or an actuator thereof. This produces a device in which the valve body position can be controlled remotely.

In a particular embodiment, the valve body can be controlled pneumatically and the line is a pneumatic line by means of which it is possible to switch between the open and closed position of the valve body by changes in air pressure. Thus, the valve body can be switched and controlled without electrical signals, so that the danger of explosion and the like is prevented.

In a particular embodiment, the valve body is a pin which is movable in the internal duct. The pin may bear against a seat, as a result of which the internal duct is closed in said location. Such a valve can readily be assembled.

In one embodiment, the spray-drying device comprises a pretensioner for pretensioning the valve body to a closed position using pretension. This improves safety and further prevents the product from being contaminated. In one embodiment, a second injection pipe is present on which a second spray-drying device is placed in the same tower. By using a spare injection pipe, it is possible to switch from one set of spray-drying devices to the other during production.

Another aspect of the invention relates to a system for spray-drying comprising a store, a line which is connected to this store and to an injection pipe which ends in a spray- drying tower, in which a spray-drying device according to one embodiment of the invention is connected to one end of the injection pipe. According to an advantageous embodiment, the system comprises a control unit with an interface by means of which the controllable valve body can be instructed to open or close, the instruction being passed to the spray-drying device via a line, preferably a pneumatic line, via a suitable connection to the spray-drying device. Although the invention will be described with reference to a number of preferred embodiments, the invention is not limited thereto. The embodiments to be described are only examples of possible implementations of the invention and it will be clear to those skilled in the art that the advantages of the invention can also be achieved in other ways.

The invention will now be described with reference to the figures, in which:

Fig. 1 shows a diagrammatic view of a system for spray-drying according to a first embodiment;

Figs. 2a and 2b show a perspective view and longitudinal section, respectively, of a spray-drying device according to a first embodiment of the invention,

Fig. 2c shows a cross section along line Hc-IIc of the first embodiment;

Fig. 3 shows a perspective exploded view of a spray-drying device according to a first embodiment;

Figs. 4a and 4b show a perspective view and longitudinal section, respectively, of a spray-drying device according to a second embodiment;

Fig. 5 shows a longitudinal section of a spray-drying device according to a third embodiment, and Fig. 6 shows a diagrammatic view of a spray-drying device according to the third embodiment.

Fig. 1 shows a view of a system for spray-drying according to a first embodiment The system 1 comprises a store 2 connected to a spray-drying tower 4 via a supply line 3. A substance to be spray-dried, such as milk, is passed to the tower 4 from store 2.

In one embodiment, the spray-drying tower 4 is open at the top side. Hot air is blown into the tower 4 via the open side. Spray nozzles 5 spray droplets into this hot air stream, as a result of which these droplets are entrained by the stream and the water present in the droplets evaporates.

In another embodiment of the spray-drying towers 4, the top side is closed and the spray nozzles 5 are introduced into the tower by means of an injection pipe 6 and the air can also come from the side.

Air supply 29 with heating 20 supplies hot air to a diagrammatically illustrated mixing chamber 39 of the spray-drying tower 4. The hot air supply 29 is illustrated diagrammatically.

Fig. 1 shows the embodiment of a tower 4 with an injection pipe 6 which is connected to the mixing chamber 39 downstream.

In the illustrated embodiment, injection pipe 6 branches out into four branches 7-10, in which case a spray-drying device 11-14 is placed at each end of the branch 7-10 according to a first embodiment of the invention. Of course, it is also possible to use a part of the invention without the branch. Each of the spray-drying devices 11-14 is connected to a diagrammatically illustrated control device 19 via a control line 15-18. The control line 15-18 is of a suitable kind, for example an air line which can be used for pneumatic control. In one embodiment, conditioned air is used for controlling a function of the spray-drying devices 11-14. One outlet 21 of the spray-drying tower 4 is connected to a temporary store 25 for collecting the spray-dried products. From the temporary store 25, the spray-dried products are passed 23 on to a fluidized bed 26 and/or discharged and/or partly returned 24 to the spray-drying tower 5.

Figs. 2a and 2b show a first embodiment of a spray-drying device 11-14. Spray-drying device 11 is illustrated together with an end of an injection pipe 7. Via the injection pipe 7, which is illustrated in the figure by means of dashed lines, the product to be spray-dried can be supplied to the spray-drying device 11.

Spray-drying device 11 is fitted on and in the end 27 of the injection pipe 7. A suitable fitting means can be used, such as a screw thread 28, a weld or bayonet fastening. The releasable connection allows the entire spray-drying device 11 to be replaced. The end provided with screw thread 28 forms the inlet opening for product into the spray-drying device 11.

Product supplied via the injection pipe 7 will enter the spray-drying device 11 in an internal duct 30. The internal duct is linked to the injection pipe 7 and is provided with a diagrammatically illustrated valve body 31 which may, for example, be a movable valve which can be switched between an open and a closed position. Body 45 of spray- drying device 11 comprises a recess 33, into which valve body 31 can move.

In a preferred embodiment, a pretension is applied in order to bring the valve body 31 to the closed position. The pretension may be applied by a spring body or the like. This will close the inlet when the supply pressure in the pneumatic line drops below a certain threshold value, thus preventing the formation of droplets.

Via the line 15, in this case a pneumatic line, the spray-drying device 11 is connected to the control device 19 so that a user can control the position of valve body 31 remotely and can open or close the latter at suitable points in time, thus starting or ending the supply of product. Downstream of cavity 30, a turbulator 40 is arranged in cavity 41 past which the product to be spray-dried can move so that turbulence is imparted and so that the product can reach cavity 42 which is linked to the orifice 43 via which the product can leave spray-drying device 11 and can enter the spray-drying tower 4. The orifice 43 forms the outlet opening of the internal duct of the spray-drying device 11.

Turbulator 41 and orifice 43 are accommodated in a second spray-drying body part 46 which is connected, via a suitable connection, to the first spray-drying body part 45, which is connected to the injection pipe end 27. The suitable connection between the spray-drying body parts 45 and 46 may be a screw connection or a bayonet fastening. By using a suitable connection, the turbulator can be accommodated between the two bodies and be positioned therein.

By closing the valve body 31, the supply of product is blocked and the releasable second spray-drying body part 46 is situated directly downstream of the valve body. In use, the second part 46 can be released from the first part 45 in order to remedy, for example, blockages of the orifice 43.

As the valve body 31 and the orifice 43 are situated a short distance from one another in the spray-drying device 11, dripping after the valve 31 has been closed is very limited and/or prevented completely. According to the prior art, dripping would contaminate the tower. In addition, the start-up procedure for activating the spray- drying process with system 1 can take place in a more controlled and more rapid manner. The pressure in the product to be sprayed in the injection pipe can be generated very close to the orifice 43, while the valve body 31 is closed. When there is sufficient pressure, the valve body 31 can be opened and spraying begins almost immediately.

According to the invention, it is also possible to replace part of the spray-drying device 11 during production, in order thus to resolve a fault. In contrast with the prior art, system 1 does not have to be closed down completely. The clogging up of the orifice 43 and/or of the turbulence chamber/turbulator during production results in an increase in pressure during spraying and, in the prior art, would lead to the process being stopped and the production run being interrupted. However, according to the invention, the production run can continue and the spray-drying device 11 in question which has a clogged-up orifice 43 can be shut down, while the other clear spray-drying devices can continue to spray as the supply to the blocked spray-drying device can be stopped.

Since the valve is situated in the first spray-drying body part 45, the second part 46 can be detached therefrom and be replaced.

In one embodiment, two injection pipes are present in the spray tower. When the active injection pipe is blocked, the spare injection pipe can take over, and the blocked injection pipe can be repaired. In case all spray nozzles/valves are part of one supply line, the blocked injection pipe is shut down and another injection pipe takes over. Maintenance is then carried out after production has finished. As the valve 31 forms part of spray-drying device 11, regular maintenance can be carried out on this valve by removing spray-drying device 11, that is to say both spray- drying device parts 45, 46, from the end of the injection pipe 7. The valve is easy to maintain and can readily be replaced, if necessary. Due to the way they have been fitted, other parts of the spray-drying device 11 can also readily be cleaned according to the invention and thus a significant time saving can be achieved here.

The valve 31 according to the invention also replaces a non-return valve in the spray- drying device 11 which may possibly be present. This results in an altogether more efficient switch than is the case in the prior art, where there would be both a non-return valve in spray-drying device 11 and a control valve in the supply injection pipe 7.

The use of a pneumatic control circuit is advantageous as the risk of explosion is absent. In an advantageous manner, according to the invention, an injection pipe with a large number of branches 7-10 may be installed in the spray-drying tower 4 and each of said branches can be controlled separately via the control device. As a result thereof, it is for example possible to have twelve injection pipes end in the spray-drying tower, each of which is provided with its own spray-drying device. During a production run, eight spray-drying devices can be switched on and four can be kept as spares. When a spray- drying device becomes clogged up, it can be switched off and one of the spare four spray-drying heads can additionally be switched on. Consequently, the production run does not have to be interrupted and a time saving and thus cost saving is achieved.

The second spray-drying device part 46 comprises a cavity 41, which forms part of the internal duct running through the device. In a radial direction, the cavity 41 is provided with additional recesses 64 and 65. The additional recesses, produced by milling, are formed to allow product to be passed in the direction of the orifice 43. The four (if desired three) additional cavities 64,65 enlarge the original cavity 41 which contains the round turbulator 67, as a result of which the risk of blockage by the product is significantly reduced. According to a particular aspect, the present application provides a further invention in the form of a spray-drying device with a housing and a cavity, in which a turbulator is accommodated, the cavity being provided with two or more additional cavities which enlarge the original cavity in the radial direction, so that the risk of blockage is reduced. The additional cavities are configured such that parts of the original cavity remain and can adjoin the turbulator accommodated in the cavity. The additional cavities enlarge the cavity in a number of places, without increasing the smallest diameter (the largest round object fitting the original cavity) of the cavity.

Fig. 3 shows the spray-drying device 11 in exploded view. Between the spray-drying bodies 45, 46, an O-ring 50 is present which provides a sealing connection between the two bodies. Grooves 52 can be seen on turbulator 42 by means of which turbulence is imparted to the product to be spray-dried.

Orifice disc 54 is fitted near a distal end of the second spray-drying device part 46 and can be replaced.

Preferably, two different connection types are used for the connection between the spray-drying device parts 45, 46 and the connection between the spray-drying device and the injection pipe end. This makes it easy for the user to detach one of the two devices by means of suitable tools and carry out a replacement, if necessary.

Cavities 41 and 30 together form the internal duct through the housing of the spray- drying device running through the two housing parts 45,46.

Fig. 4a shows a perspective view of another embodiment of a spray-drying device 60. Fig. 4b shows a longitudinal section along line IVb-IVb. On an outer side of the second spray-drying device part 62, a control line connection 68 can be seen, in which a control line 69 can be accommodated.

Controllable valve 62 can be controlled remotely and switched between an open and a closed position.

In one embodiment (not illustrated), the controllable valve 31 or 62 is a pin. The pin preferably rests on a seat and thus forms a valve body. By means of the control line, the pin can be moved away from or against the seat and can thus form an open and a closed valve.

Fig. 5 shows a longitudinal section of a third embodiment of a spray-drying device 100. A spring 101 is fitted in cavity 102, formed between housing part 103 and housing part 110. The spring 101 exerts a pretension by means of which a piston 105, surrounded by O-ring 106, is pushed onto a seat 107.

A connection 108 is formed on the housing 103 for the supply of compressed air. Connection 108 ends in duct 109. When compressed air is supplied, piston 105 can move according to arrow 119, against the pretension of spring 101. Housing parts 103 and 110 are connected to one another by means of a screw thread connection, and in this case, the spring 102 is locked between the two parts. An increase in compressed air pressure results in the displacement of the piston 105 and of the pin 117 coupled thereto. Via a seal 116, the pin 117 is connected to the cavity 113 and ultimately to the shut-off nipple 114, which can therefore also move according to arrow 119 when the piston moves.

When the pressure of the pressure line drops, the compressed air confined in the cavity 112 will leave the device 100 again via duct 109. Under the effect of the spring 101, the piston moves back to its initial position. The cavity 112 is closed by a piston with an CD- ring 116.

The product to be sprayed is introduced into the cavity 113 via inlet 118 and can leave the spray-drying device 100 through the orifice 104.

In its initial position, the orifice is closed by means of a shut-off nipple 114 which bears against a seat 115. The nipple 114 is connected to the piston 105 via a pin 117 and will, when controlled by compressed air, carry out the same movement opposite to the direction of flow of the product and come off the seat 115, so that product can leave the device 100 via cavity 121 and through the orifice 104. The pin 117 and the shut-off nipple 114 form part of the controllable valve body which is situated inside the first housing part 103. The ends of the pin 117 and the shut-off nipple 114 are also situated inside the second housing part 129, and in this case the pin 117 extends inside the second housing part 129. An advantage thereof is that the first housing part 103 can readily be extended by extending a sleeve which forms part of the first housing part 103 and is connected to the second housing part 129, the diameter of the sleeve substantially depending on the diameter of the pin 117.

Fig. 6 shows a view of the assembled spray-drying device 100 on an end of the injection pipe 135. The control line 131, via which air can be supplied to the spray- drying device 100 in order to control a valve body in the spray-drying device 100 can also be seen.

Likewise, the product line 132 can be seen via which product, supplied via injection pipe 135, can be supplied to the spray-drying device 100. An intermediate piece 134 is connected to injection pipe 135, comprising a tube 130 on which the spray-drying device 100 is fitted. The product is passed to line 132 via a branch 136.

Fig. 6 also shows more clearly that the third housing part 129 is a separate housing part which does not form part of housing 103/110 and which accommodates the main parts of the controllable valve. However, the valve extends into the second housing part 129, as can be seen in Fig. 5.

In one embodiment, an adjustment mechanism is present, in particular in cavity 113, for adjusting the length of the pin in order to enable the nipple 114 to sealingly bear against seat 115. It will be clear that several embodiments are possible without departing from the scope of the invention.