Field of the Invention The present invention relates to an infusion system for heat treatment of liquid or semiliquid food products.

The present invention also relates to a method for heat treating liquid or semiliquid food products.

The present invention also relates to the use of the system and/or the method.

Background of the Invention

In the food and beverage industries it is customary to improve shelf life by subjecting the food or beverage product to heat treatment.

Typically, the heat treatment is a pasteurization, a heat treatment to provide extended- shelf-life (ESL) or UHT (ultra-high temperature) treatment.

Pasteurization is a process in which water and certain packaged and non-packaged liquid foods (such as milk or fruit juice) are treated with mild heat, usually to less than 100 °C, for a period necessary to eliminate pathogens, typically 10-30 seconds or more e.g. up to 1-2 minutes, depending on the product and/or whether enzyme deacti- vation or microbial deactivation is required. The pasteurization process also extends shelf life of the food products. The process destroys or deactivates enzymes that con- tribute to spoilage of the product. Pasteurization also destroys or deactivates microor- ganisms including vegetative bacteria, but not bacterial spores. Thus, the risk of in- gesting food containing pathogens is reduced, which also reduces the risk of diseases and/or spreading thereof. ESL products are the products that have been treated in a manner to reduce the micro- bial count beyond normal pasteurization, followed by packaging under hygienic con- ditions. ESL products have a defined prolonged shelf life under refrigeration condi- tions. At present there is no generally accepted definition of ESL heat treatment. ESL heat treatment to provide ESL products, e.g. ESL-milk, fills the gap between pasteuri- zation and ultra-high temperature treatment (UHT). Extended-shelf-life (ESL) heat treatment on milk is usually applied at 120-135°C for 1-4 seconds to extend shelf life of processed liquid milk products.

UHT treatment is mostly used to sterilize liquid food by heating it above 135 °C for 2 to 5 seconds. UHT is most commonly used in milk production, but the process is also used for fruit juices, cream, soy milk, yogurt, soups, honey or stews in order to kill spores, microorganisms, vira etc. UHT milk can for example be stored for a few months without cooling.

Liquid food products (in the following just “the product”), which undergo such heat treatment, is typically fluid products or semi-fluid products, for example dairy prod- ucts, fruit and/or vegetable-based products, juice from fruit and/or vegetables, vegeta- ble based milk substitutes, such as milk substitutes based on soy, oat, nuts, almonds and/or mixtures thereof, drinks of any kind, e.g. beer, wine, soft drinks, as well as cul- inary products such as soups, broth, stews, gravies, dressings, honey, desserts, e.g. puddings, and/or condiments. The condiments optionally comprise small particulates.

Examples of dairy products are liquid dairy products such as milk, cream and/or yo- ghurt or similar fermented milk or cream based products and/or milk based liquid, whey or liquid or semi liquid food products based on whey or semi liquid desserts.

It is common to use direct heating by steam in an infusion system when heat treating such liquid or semi liquid food products.

In an infusion system the product is led into an infusion chamber where the atmos- phere is made up of saturated steam (or steam close to the saturation point) which is maintained at a given pressure and temperature. Saturated steam (or steam close to the saturation point) is fed to the infusion chamber in order to maintain the desired tem- perature in the infusion chamber, so as to ensure the desired heat transfer to provide pasteurisation, ESL treatment or UHT treatment. The product is led into the infusion chamber through a nozzle and is heated by the steam condensing into the product, thereby elevating the temperature to the desired level in accordance with a set point.

The product falls through the infusion chamber with limited or no contact with the inside of the infusion chamber while it is being heated by condensing steam (also called the infusion process) and is removed through an outlet placed in the bottom of the infusion chamber

The bottom of the infusion chamber may be equipped with a concentric cooler cover- ing the lower part of the infusion chamber.

During the infusion of the product to be heated, air is liberated from the product. This creates a semi-gaseous atmosphere in the chamber, especially in the top thereof, which makes the infusion chamber less efficient in its function because it decreases the par- tial pressure of steam in the infusion chamber and thus reduces the heat transfer to the product.

An example of such an infusion system for heat treating liquid dairy products is shown in EP 2381793 B1 also published as US 2012/027901 Al. The infusion cham- ber has two separate steam injection passages and thus has two separately controllable steam flows. The product as well as the steam is introduced into the infusion chamber from a nozzle plate / annular nozzle placed in the very top of the infusion chamber.

Each steam injection passage is provided with a valve controlling the steam flow into the infusion chamber. A first steam injection flow provides steam to the central part of the infusion chamber. This first steam inlet is the main steam inlet. The first main steam inlet is surrounded by a concentric product inlet or nozzle that provides a falling circular flow of product. A second steam inlet is arranged concentrically outside the product flow.

The construction of the top (with the concentric steam flows and product flow) of the infusion chamber is complex and expensive to produce. Further, the known infusion chamber, and in particular the complex construed product and steam infusion top, is expensive to keep in production mode due to time consuming and expensive service or maintenance. Further, the known infusion chamber is complex with respect to con- trolling steam flow. For example, the two separate steam injection passages for providing steam into the infusion chamber require two separately controlled valves. In addition, there may be increased risk of the product outlet being clogged by coagulat- ed and/or burnt-on product at, near or inside the product outlet. This is because of the close proximity of the product outlet and the first and/or second steam outlets, thus the increased risk of heat-exposure to the product outlet. Further, this may increase the risk of partial clogging of the product outlet which may cause that the liquids are in- troduced into the infusion chamber as finely divided drops or even an aerosol, which results in that duration of the fall time is out of control with a further increased risk of burnt taste in the product.

EP 0402965 A2 discloses a UHT system for treatment of food product, comprising two steam inlets arranged on opposite sides of the infusion chamber and a central product tube inlet. The central tube inlet is divided into three deflection cups arranged on a row. Each deflection cup generates an umbrella-shaped flow of product that falls through the infusion chamber. However, the design of the deflection cup is likely to form a local hot-spot where the product can be burned and thus affect the quality of the treated product.

Thus, there is still a need for less complex constructions of steam infusion systems for heat treatment of liquid or semi liquid food products.

Object of the Invention Thus, it is an object of the present invention to provide a simple and effective con- struction which is applicable in the heat treatment of liquid or semi liquid food prod- ucts as well as a method therefore, while also maintaining a high rate of heat transfer from steam to product. Further, it is an object of the present invention to provide a steam infusion chamber construction which is applicable in the heat treatment of liquid or semi liquid food products as well as a method therefore. In addition, it is an object of the present invention to provide a steam infusion cham- ber construction which is simple in its construction and thus less expensive to fabri- cate, repair and/or maintain in service. It is also an object of the present invention to provide an effective and simple control of the steam entry into the infusion chamber construction as well as a method there- fore.

It is also an object of the present invention to provide an effective and gentle steam entry into a steam infusion chamber, which provides a laminar steam flow in the infu- sion chamber.

It is finally an object of the present invention to provide an effective product and gen- tle steam entry into a steam infusion chamber, which protects the product from dis- turbance and atomization; which ensures predictable fall and holding times and/or which reduces the risk of the product having a burnt taste.

Description of the Invention

These objects are met by an infusion system for heating a liquid or semi liquid food product by direct contact with steam, including an infusion chamber limited by an infusion tank, said infusion chamber having a product inlet for the food product to be heated in its upper area and a product outlet for the heated food product in its lower area, and where said product inlet is ring-shaped and the product is provided as a ring- shaped product stream falling freely down though the infusion chamber, said infusion chamber further having a steam inlet for the steam in the upper area of the infusion chamber, wherein

- said ring-shaped product inlet inside the upper area of the infusion chamber is ar- ranged to be suspended below an upper wall of the infusion chamber,

- said steam inlet is provided as a single steam inlet passage which provides the steam into the infusion chamber via one or more steam entry ports in a top or side of the in- fusion chamber above and/or around the ring-shaped product inlet of the infusion chamber, and said steam entry port or openings in the top of the infusion chamber surround the ring-shaped product inlet and are arranged between the ring-shaped product inlet and the side of the infusion chamber. This construction provides a simplified steam addition system because it is only nec- essary to use a single common feed for steam flow for introducing steam into the infu- sion chamber. This reduces production costs significantly. Further, less parts needs service, repair or maintenance whereby the running costs are also reduced. Further, the greatly simplified construction of the steam introduction to the infusion chamber also greatly simplifies the control of the infusion chamber since only a single steam flow has to be controlled according to the desired process conditions (temperature in chamber and/or product, required amount of steam) depending on the nature and/or flow of the product to be heated in the infusion chamber. Another important effect of suspending the infusion nozzle system lower in the infusion chamber is that there is less interference with the infusion process and the steam entry which means that the infusion chamber will also work more efficient as a separator of air. Thereby, evacua- tion of air may be ensured at lower energy losses as less steam is lost in the process through an air outlet as discussed further below.

The infusion system for heating a liquid or semi liquid food product by direct contact with steam includes an infusion chamber limited by an infusion tank. The infusion tank comprises a tank top and tank bottom part with at least one tank wall there- between. The infusion tank is usually cylindrical, but may also be of oval or polygonal cross section, e.g. square rectangular, pentagonal, hexagonal, heptagonal, octagonal etc. The product inlet for the food product to be heated is in the upper area of the infu- sion chamber, and the product outlet for the heated food product is in its lower area. The bottom part of the infusion tank is usually funnel shaped to direct the heated product to the outlet at the bottom of the tank, such as the bottom end of the funnel shaped bottom.

The main heat transfer occurs between the steam supplied between the outside circum- ference of the freely falling product stream and the chamber side wall. This also re- duces the risk of product adhering onto the inner wall and thus reduces the risk of bumt-on product on the inner wall of the infusion chamber. Thereby the frequency and/or time periods necessary for shut downs in order to clean the inner chamber walls are reduced significantly. The ring-shaped product inlet inside the upper area of the infusion chamber is ar- ranged to be suspended below the inner top surface of the infusion chamber. By sus- pending the product inlet below the inner top surface of the infusion chamber, a pas- sage between the top inner surface and the product inlet allows steam to pass freely between the top of the infusion chamber and the suspended ring-shaped product inlet and into the space surrounded by the falling product flow, as also discussed further below.

Thereby, the heat transferred from steam to product is maintained at a high level, be- cause the steam is in contact with the outside surface as well as the inside surface of the freely falling product stream even though steam only enters the infusion chamber at the outer circumference of the falling product flow. Thus, the product inlet con- struction enables that a single steam inlet passage can be used, since there is no longer need to actively supply a separate steam flow to the space surrounded by the freely falling product flow.

Preferably, said steam entry port or openings in the infusion chamber are dimensioned to support a laminar steam flow into and/or inside the infusion chamber. Hereby is obtained that there are no or only very small disturbances of the product flow. A turbulent steam flow in the infusion chamber may “tear” off droplets of prod- uct from the freely falling jets or curtain of product and allow the droplets of product to adhere on the inner wall and possibly burn onto the hot surface. Further, a turbulent steam flow inside the infusion chamber may cause “torn off" droplets to be suspended by the turbulent steam in the infusion chamber, causing in- creased residence time of the droplets giving risk of a burnt flavour in the product.

Further, a laminar flow or substantially laminar flow in the infusion chamber ensures that the injected steam passes above the suspended product nozzle and into the inner free space surrounded by the freely falling product flow.,

As mentioned above, the steam entry port(s) are arranged in the tank top or the tank wall of the infusion tank above and/or around the ring-shaped product outlet. This steam entry port or openings in the infusion are preferably provided as a number of openings, such as 3, 4, 5, 6, 7, 8 or more. These openings are equally distributed around the ring-shaped nozzle. Alternatively, said steam entry port is provided as a single ring-shaped opening which surrounds the ring-shaped nozzle. These alternative steam inlet layouts both ensure even distribution of steam in the in- fusion chamber in order to optimize the contact area between steam and the falling product stream. Thereby the heat transfer to the product is also optimized.

The steam infusion system comprises a single valve which is arranged in the steam inlet passage to control the flow of steam to the steam inlet or inlets into the infusion chamber. This greatly simplifies control of the steam injection flow into the infusion chamber, since the single valve controls the heat input into the infusion chamber by controlling the amount of steam injected into the infusion chamber. Further, a less complex system is provided and therefore the production costs as well as service, re- pair and/or maintenance are kept at a minimum.

The liquid or semi liquid product is introduced into the infusion chamber through said ring-shaped product inlet. The ring-shaped product inlet is suspended below the inner wall of the tank top. The ring-shaped product inlet is shaped as a distribution unit with one or more product inlet passages and with one or more nozzles arranged at the low- ermost side thereof to provide a downward freely falling flow of the product to be heated. The distribution unit is preferably formed by a ring-like shaped pipe member. The downward flowing product surrounds fully or partly an inner free space, at the centre of the infusion chamber.

By suspending the product inlet below the tank top, a passage between the inside of the tank top of the infusion tank and above the product inlet is provided. This passage allows steam to pass freely from the steam inlet(s) and into the central free space without having to travel through the “ring” of the freely falling product which is re- leased from the nozzle(s). Hereby the product flow can be heated by contact with steam from both sides, without disturbance from the steam. The steam provided to the infusion chamber at the radially outer side of the product flow will thus be responsible for all or most of the heat transfer to the product flow, and the rest will enter the prod- uct on the radially inner side in an auto-adaptive optimization process. The product inlet is described above as ring-shaped. This may, as implied, include a circular or annular product inlet shaped a ring that is a closed ring. The ring-shaped product inlet is not necessarily circular; it may also be oval or polygonal. A polygonal ring like member is e.g. formed of a number of straight pieces which are joined to- gether in angles to form the polygonal shape. By polygonal is meant a closed ring with 3, 4, 5, 6, 7, 8 or more sides formed of straight pieces.

In a simple configuration, the distribution unit is formed by a continuous pipe member or a number of pipe member joined together. The pipe member or pipe members de- fine a distribution path for distributing the product to the individual nozzles.

In another configuration, the distribution unit comprises at least one top part and at least one bottom part which are joined or attached together. The top and bottom parts each form a portion of the distribution path, such as an integrated channel. The distri- bution channel may also be formed by arranging the pipe member(s) within the top and bottom parts.

The top part(s) and/or the bottom part(s) are formed as solid or hollow pieces which act as insulating or cooling means for the product inlet. Cooling air is optionally led through the hollow structure or internal cooling channels for providing the cooling air to or near the nozzle(s). The cooling air is optionally introduced via an air inlet and an air outlet arranged in the tank top or in the product inlet passages.

The said ring-shaped pipe member is optionally provided with insulating or a cooling means. The cooling means are e.g. internal cooling channels or double walled pipes/walls of the pipe member. The double walled pipe member may form a cooling jacket of means to provide cooling air to or near the nozzle(s), e.g. through an air out- let gap near the nozzle(s).

The above cooling means protects at least part of the product inlet from heat exposure from the surrounding steam in the infusion chamber. This reduces the risk of the product inlet being blocked e.g. at the nozzles and/or by product bumt-on/adhering to the inner side of the pipe member or the integrated channel as a result of the heat ex- posure from the outside of the distribution unit. The product inlet comprises one or more nozzles in the product inlet pipe. The nozzle may e.g. form a ring-shaped slit, optionally divided into subsections, i.e. with a nozzle forming part of the ring in each of the subsections of the product inlet.

Alternatively, the nozzle(s) may be formed by one or more rows of radial slits or with slits which are angled relative to radial position.

The ring- or annular-shaped nozzle or nozzle slits are preferred when heating products that contains particulates, pulp and/or fibres as e.g. may be the case in liquid food products based on fruits and/or vegetables, such as juices

Alternatively, the nozzle(s) may be provided as one or more rows of circular, oval or polygonal holes.

The nozzle release angle is preferably made so that the freely falling product converg- es towards the center of the infusion chamber shortly before the exit thereof.

Further, the ring-shaped product inlet is configured to provide a forced flow of the product inside a distribution path of the distribution unit. The distribution unit is pref- erably shaped so that the product is introduced at an angle relative to the distribution path, thereby forcing the product to flow in a certain direction along the distribution path to the nozzles. As the distribution unit is a closed ring-shape, the product is forced to flow in a certain rotational direction relative to the axial centre of the distri- bution unit. As such, the distribution path forms an endless loop, thereby allowing for the product to continuously circulate inside the distribution path before exiting through the nozzles. This ensures that the pressure and flow of the product is applied equally to all the individual nozzles. This further allows for a full/optimum control of the product as it exits the nozzles and starts to fall freely through the infusion cham- ber.

The product is preferably supplied via a plurality of product inlet passages, such as 2, 3, 4, 5, 6 or more, distributed over the circumference of the distribution unit. The plu- rality of product inlet passages is preferably evenly distributed over the circumference of the distribution unit. The local arc length between adjacent product inlet passages may be half of the circumference, one-third of the circumference or one-quarter of the circumference, but other arc lengths may also be used. The forced flow also provides a very effective cooling of the body of the distribution unit, as mentioned later. At least the distribution unit or the product inlet passages comprises an inlet portion, where said inlet portion has a curved shape or is arranged at an angle relative to a plane defined by the distribution plane.

The applicant has found that the flow in conventional product inlet designs decreases towards the end of the feeding channels which leads to severe issues with CIP and deposits inside the feeding channel. The present product inlet design solves these problems.

The inlet portion arranged at the distribution path is preferably curved where the cur- vature is substantially aligned with the circumference direction of the distribution path. The inlet portion may also have a substantially straight shape where this straight inlet portion is arranged at angle relative to the circumference direction of the distribu- tion path. The angle is preferably an acute angle. This inlet portion may form an inte- grated part of the distribution unit and/or of the product inlet passages.

An air outlet is preferably provided at the top of the infusion chamber, such as one or more central air outlet(s) in the top wall and/or through one or more air outlet(s) along or near the uppermost part of the infusion chamber’s outer wall or outer area of the tank top. This air outlet can withdraw any air and/or other gasses released from the product during the passage down through the infusion chamber while being heated. Gasses that are released from the product may occupy an increasing volume of the infusion chamber unless they are withdrawn from the infusion chamber. An increasing amount of released gasses present in the infusion chamber will reduce the partial pres- sure of steam in the infusion chamber. This will decrease the heat transfer from steam to the product and result in an overall reduced efficiency of the infusion system unless these gasses are withdrawn.

The suspended product inlet nozzle also allows the gasses to be withdrawn via an air/gas outlet arranged centrally at the top of the infusion chamber. The above mentioned objects area also met by a method for heating a liquid or semi liquid food product in an infusion system with an infusion chamber, to which the food product to be heated is supplied in an upper area of the infusion chamber, and from which the heated food product is discharged in a lower area of the infusion chamber, where the food product to be heated enters the infusion chamber and flows down through the infusion chamber as a freely falling downward flow, and where steam is supplied to the upper area of the infusion chamber, and where the steam is in direct heat exchange with the product flow, wherein

- the food product is supplied to the infusion chamber as a ring-shaped product flow from the suspended ring-shaped product inlet inside the upper area of the infusion chamber,

- said steam is introduced into the infusion chamber through a single steam inlet pas- sage and is distributed into the infusion chamber via one or more steam entry ports in a top or side of the infusion chamber, and where said steam entry port or openings in the top of the infusion chamber surrounds the ring-shaped product inlet and are ar- ranged between the suspended ring-shaped product outlet and the side of the infusion chamber.

The method includes that steam preferably is distributed passively through natural aspiration to the area inside the ring-shaped product flow by passing between the sus- pended ring-shaped product inlet and the top wall of the infusion chamber. Thereby, the product is also heated by steam contact at the radially inner surface area of the freely falling product. See also the discussion thereof further above.

The method further includes that the heat input is controlled by a single valve control- ling the steam flow into the infusion chamber as also discussed further above in rela- tion to the description of the infusion system.

Preferably, the method includes that steam flow into the infusion chamber is laminar as also discussed further above in relation to the description of the infusion system.

The food product may be supplied to the infusion chamber as jets, droplets and/or as a ring-shaped liquid curtain. The product flow depends on the construction of the noz- zles on the product inlet and the flow of the product to be heated. Preferably, the food product is introduced into the suspended ring-shaped product inlet by a forced flow, e.g. a closed endless flow, and where the food product circulates continuously inside the suspended ring-shaped product inlet before exiting one or more nozzles in the suspended ring-shaped product inlet.

The inlets of the distribution unit are shaped so that product is forced to flow in a cer- tain circumferential direction, thereby causing a continuous circulation of the product inside the distribution path. The freshly introduced product thus merges with the product already located in the distribution path. As mentioned earlier, this allows for an equal product flow and pressure over all the nozzles.

The forced circulating flow also provides a very effective cooling of the body of the distribution unit since the cold product, prior to heating in the infusion chamber, is circulated with a very short residence time. The residence time may be one second or less. This ensures that no hot-spots are formed along the product inlet where the prod- uct can potentially burn on during production which may both affect the quality of the product and make cleaning in place far more difficult.

The method further includes that air is withdrawn from the infusion chamber at the top end thereof, in particular through central air outlet(s) in the top wall and/or along or near the uppermost end of the infusion chamber’s outer wall or outer area of the tank top as also discussed further above in relation to the description of the infusion sys- tem. This provides as little as 5% (by volume) or lower, e.g. 1-3 % (by volume) of air in the infusion chamber, or less.

The method is preferably applied as heat treatment of the liquid or semi liquid food product in a pasteurisation treatment, an extended shelf life heat treatment (ESL) or a ultra-high temperature treatment (UHT). Each of these heat treatments are defined by the temperatures to which the products are heated and the time applied for the heating of the products cf. the definitions given in the background section. Prior to being introduced into the infusion chamber, the steam can be generated with the required temperature/pressure and be controlled with a regulation valve for steam. It can also be heated to the temperatures needed during the relevant heat treatment in a steam generator. The temperatures to obtain these resulting heated (product) tempera- tures depend on whether the heating is to obtain pasteurisation of the product; ESL heat treatment or UHT heat treatment.

In the method it is preferred that the steam is supplied by a steam heating medium, such as saturated steam (at the prescribed temperature and pressure applied in the in- fusion chamber during the heat treatment) or at least the steam is close to the satura- tion point, e.g. the steam contains at least 90% (by volume) or preferably at the least 95% by volume or at best above 97% by volume of the possible content of water va- pour at the prescribed temperature and pressure used for the relevant heat treatment. This is preferred in order to minimize evaporation of water from the liquid product and to optimize heat transfer from the steam to the product. This is also described fur- ther above (in the background section). The pressure varies depending on the heat treatment and may e.g. be close to atmospheric pressure during pasteurisation and up to e.g. 3 bar during UHT, while during ESL heat treatment the pressure is usually a little lower than at UHT heat treatment.

The present invention also relates to use of an infusion system as described above or below and/or a method as described further above or below for providing a pasteurisa- tion, an extended shelf life heat treatment (ESL) or a ultra-high temperature treatment (UHT) of a liquid or semi liquid food product, such as dairy products, such as milk, cream and/or yoghurt or similar fermented milk or cream based products, whey or liquid or semi liquid food products based on whey; milk based liquid or semi liquid desserts; fruit and/or vegetable-based products, juice from fruit and/or vegetables, vegetable based milk substitutes, such as milk substitutes based on soy, oat, nuts, al- monds and/or mixtures thereof, drinks of any kind, e.g. beer, soft drinks, as wells as culinary products such as soups, stews, broth, gravies, dressings, honey, desserts, such as puddings, and/or condiments with or without small particulates. Description of the Drawing

The present invention will be described in details below with reference to the draw- ings in which

Fig. 1 shows a vertical cross section of the steam infusion apparatus,

Fig. 2 shows a perspective view of the outside of the top section of the steam infusion apparatus,

Fig. 3 shows a perspective view of the inside of the top section of the steam infu- sion apparatus,

Fig. 4 shows a first sideview of the top section of the steam infusion apparatus,

Fig. 5 shows a cross sectional view of the top section of the steam infusion appa- ratus through line A-A shown in figs. 6-7,

Fig. 6 shows a second sideview of the top section of the steam infusion apparatus (perpendicularly to side view in fig. 4),

Fig.7 shows a cross sectional view of the top section of the steam infusion appa- ratus through line B-B shown in figs. 4-5,

Figs. 8a-d show various possible nozzle designs for the product inlet, and Figs. 9a-b show an alternative embodiment of the product inlet. The same items bear the same reference signs on all figures. Thus, each single feature is not necessarily discussed in relation to every single figure.

Detailed Description of the Invention

Fig. 1 shows a vertical cross sectional view of an infusion system 1 according to the present invention, which is primarily intended for pasteurisation, ESL treatment or UHT treatment of liquid or semi liquid food products P.

The infusion system 1 has an infusion tank 2 with a tank top 3, a tank bottom 4 and one or more tank walls 5. The product P is led into the infusion chamber 7 at the top 8 where the atmosphere is made up of saturated steam (or steam close to the saturation point) which is maintained at a given pressure and temperature. Saturated steam (or steam close to the saturation point) is fed to the infusion chamber through a steam inlet passage 15 and into the infusion chamber via steam entry ports 16 in order to maintain the desired temperature in the infusion chamber, so as to ensure the desired heat transfer to provide pasteurisation, ESL treatment or UHT treatment. The number of steam entry ports 14 shown on the drawings (four openings 16 are drawn) is illus- trative only. The tank top 3 of the infusion tank 2 is e.g. attached to the tank walls 5 by flange members 20 and attachment means e.g. bolts and nuts.

The product P is led into the infusion chamber 7 through a product inlet 10. The prod- uct inlet 10 comprises a product inlet passage 12 and a distribution unit shaped as a ring-shaped pipe member 13 (ring shape is optional and may be another shape as dis- cussed above). The pipe member 13 has a number of nozzle openings 14 at the low- ermost side of the pipe 13.

The product inlet pipe 13 with nozzles 14 (for illustrative purposes shown as being ring-shaped in the figures) is arranged inside the upper area 8 of the infusion chamber. The product inlet pipe 13 is arranged to be suspended below the tank top 3/inner top surface of the infusion chamber 7. By suspending the product inlet below the inner top surface of the infusion chamber 7, the passage between the top inner wall and the product inlet allows steam to pass freely between the chamber top 3 and the suspended product inlet pipe 13 as shown with arrow S in figs. 1, 3, 5 and 7. Thereby the steam is allowed to pass into the space 19 (see fig 1) surrounded by the falling product flow.

The nozzles 14 and/or the product pipe 13 can be insulated from the heat-exposure in the infusion chamber 7, e.g. by cooling channels in the pipe 13, near the nozzles 14, the double walled pipes 13 or by providing an air nozzle near the nozzles 14 to expel cooling air (none of these are shown in figs.).

The product P falls freely down through the infusion chamber 7 and is heated by the steam condensing into the product, thereby elevating the temperature to the desired level in accordance with a set point. The set point depends on whether it is intended to heat the product for pasteurisation, ESL or UHT treatment as discussed further above.

The nozzles are designed to make the ring-shaped curtain/jets/droplets of product P converge shortly before the entry into the exit 11 as illustrated by the dotted lines P in fig. 1. An air outlet 17 is provided at the top of the infusion chamber 7. The air outlet is not shown in figs. 1-7 but the arrow 17 illustrates that the air outlet is e.g. provided cen- trally at the infusion tank top 3.

The product P falls through the chamber with limited or no contact with the inside of the chamber wall 5a while it is being heated by the condensing steam (the infusion process). The product P is removed through an outlet 11 placed in the bottom of the infusion chamber 7.

The bottom part 4 of the infusion tank 2 may be funnel-shaped so as to guide the product P to the outlet 11. The bottom part 4 of the infusion tank 2 may be equipped with cooling means 6. In fig. 1 a cooling jacket 6 is shown for illustrative purposes covering the lower part 9 of the infusion chamber 7. The cooling means 6 also ensures that the funnel-shaped part 4 is cold enough to avoid product burnt on the inside of the funnel shaped wall 4.

The steam S enters the upper area 8 of the infusion chamber 7 via a steam inlet pas- sage 15. The flow of steam into the steam inlet passage 15 is regulated by a single (not shown) valve. Steam enters the infusion chamber 7 through a number of steam entry ports 16. The steam inlet passage 15 is divided into a number of sub-streams corre- sponding to the number of steam entry ports 16. In figs. 1-7 four steam inlets are shown as a non-limiting example of the number of steam inlets openings.

The steam entry ports 16 are arranged to enter the space 18 radially outside the freely falling product flow P. In Fig. 3 three out of four equally spaced steam entry ports 16 are visible. As seen in fig. 3 the steam entry ports 16 are evenly spaced to surround the product flow P. The steam entry ports 16 are large enough to support a laminar steam flow inside and/or into the infusion chamber 7 as discussed above.

In figs. 1-5 the product inlet pipe 13 comprises two product inlet passages 12 for in- troducing the product into the product inlet 10. Figs. 8a-8c shows the product inlet pipe 13 in a circular variant as seen from the bot- tom. The product inlet 10 comprises one or more nozzles 14 in the product inlet pipe 13.

The nozzle 14 may e.g. form a ring-shaped slit (fig. 8d), optionally divided into sub- sections, i.e. with a nozzle 14 forming part of the ring in each of the subsections of the product inlet.

Alternatively, the nozzle(s) 14 may be formed by one or more rows of radial slits 14 (fig. 8c) or with slits 14 which are angled relative to radial position (fig. 8b).

The ring-shaped nozzle or nozzle slits are preferred when heating products that con- tains particulates, pulp and/or fibres as e.g. may be the case in liquid food products based on fruits and/or vegetables, such as juices.

Alternatively, the nozzle(s) 14 may be provided as one or more rows of circular, oval or polygonal holes as shown in fig. 8a.

Figs. 9a- 9b show an alternative embodiment of the product inlet 10’ for use in the infusion system 1. Here, an exploded view of the product inlet 10’ is shown.

The product inlet 10’ comprises a plurality of product inlet passages 12’, here four product inlet passages 12a’, 12b’, 12c’, 12d’ are illustrated. Each of the product inlet passages 12’ extend through a top member 21 of the infusion tank top 3 as illustrated in figs. 5, 7 and 9a. The top member 21 may be disc-shaped, but other shapes may also be used.

The product inlet passages 12’ are connected to the top member 21 as illustrated in fig. 9b. The product inlet passages 12’ are further connected to an alternative embod- iment of the distribution unit 22 intended to be suspended inside the upper area 8 of the infusion chamber as illustrated in fig. 1.

The top member 21 e.g. comprises the air outlet 17 arranged centrally on the infusion tank top 3. The body of the distribution unit 22 in this embodiment comprises a top part 22a and a bottom part 22b in which an enclosed distribution path 22c is arranged. The distribu- tion path 22c is e.g. defined by pipe members and/or by the top and bottom parts. The distribution path 22c is fluid communication with the product inlet passages 12’ and is designed to distribute the product P evenly to the individual nozzles 14’. The distribu- tion path 22c is preferably ring-shaped. This ensures a continuous flow of product P so that the pressure and flow of the product is applied equally to all the nozzles 14’.

The distribution path 22c is further in fluid communication with individual inlet por- tions 22d for each of the product inlet passages 12’. The inlet portions 22d preferably have a curved shape as illustrated in fig. 9a. The inlet portions 22d are e.g. orientated in the same rotational direction. This provides a forced flow (indicated by arrow 23a) of the product P into the distribution path 22c, where the introduced product P merges with the product P already located in the distribution path 22c. This causes a continu- ously rotational flow inside the distribution path 22c as indicated by arrow 23b.

This design allows for a very effective cooling as the cold product circulates continu- ously within the distribution path 22c with a very short residence time. This design also provides a better control of the product P exiting the nozzles and falling freely down through the infusion chamber 7 compared with conventional product inlets. This improves product quality and makes cleaning less difficult.

The body of the distribution unit 22 is e.g. annular shaped so that an open ended hole 24 is formed at the centrum as illustrated in fig. 9b. The hole 24 is omitted from the top part 22a in fig. 9a for illustrative purposes. This allows steam (indicated by arrow S) to flow around the body of the distribution unit 22, through the central hole and into the central space 19 of the product flow as illustrated in fig. 1.

Although not indicated in figs. 9a-b, cooling air is e.g. led through the double walled pipe member forming at least one of the product inlet passages 12a’, 12b’. 12c’, 12d’ or through a separate air let in the tank top 3. The top and bottom parts 22a, 22b op- tionally comprise internal cooling channels for circulating the cooling air within the distribution unit 22. The cooling air is e.g. led back through the double walled pipe member forming at least another of the product inlet passages 12a’, 12b’. 12c’, 12d’ or through a separate air outlet in the tank top 3.

Reference numbers

1. infusion system

2. infusion tank

3. infusion tank top 4. infusion tank bottom

5. infusion tank wall a. inner side of tank wall

6. cooling jacket

7. infusion chamber 8. infusion chamber upper area

9. infusion chamber lower area

10. product inlet,

11. product outlet

12. product inlet passage 13. product inlet pipe, ring-shaped pipe member

14. nozzle

15. steam inlet passage

16. steam entry ports

17. air outlet 18. space radially outside product flow

19. central space/space radially inside product flow

20. flange

21. top member

22. distribution unit a. top part b. bottom part c. distribution path d. inlet portions for product inlet passages

23. flow direction a. forced flow b. rotational flow

24. central hole