The present invention relates to a mixer for liquid products. More particularly, the present invention relates to a variable mixer suitable for hygienic applications, and a method for mixing liquid products flowing in a pipe.

Background

Mixers are normally used within food processing equipment, or other liquid processing equipment for hygienic applications, for providing a turbulent flow such that two or more flows of liquid product are blended after passing the mixer. Typically, such liquid processing mixer is constructed as a conduit having twisted helically-shaped plates inserted into the conduit. Each plate is twisted 180°, and followed by a subsequent plate being rotated 90° relative the previous plate. When liquids are introduced into the mixer the twisted plates will divert the flow and create turbulence which provides blending or mixing of the liquid products.

Such static mixers are widely adopted in the food processing industry and provide sufficient mixing for many different applications. However, the use of static mixers creates a number of drawbacks, namely i) mixing is always provided, also in situations where mixing would preferably be avoided, and ii) the mixer provides an increased pressure drop across the food processing equipment.

Such drawbacks are particularly of interest in food processing equipment configured to process different kind of food products, or in food processing equipment having a cleaning-in-place circuit installed.

Where food processing equipment is constructed to process different kind of food products the mixer must then be capable of providing sufficient mixing for all kinds of food products. Hence, the construction of the mixer must be adopted for the worst case, i.e. the food products requiring the highest level of turbulence.

For food processing equipment having cleaning-in-place installed the mixer will always provide a pressure drop even though turbulence preferably is avoided. A previous solution to this problem is to bypass the static mixer during cleaning-in-place, whereby additional valves and bypass conduits are required for this purpose. Outside the technical field of hygienic liquid processing variable static mixers have been suggested, e.g. as described in EP0095791 . Here, the basic concept is to provide movable discs within a conduit, which discs are divided into two semicircles arranged adjacent to each other. Each semicircle is rotatable relative the longitudinal axis of the conduit depending on the amount of turbulence it is supposed to achieve.

Although the general concept of movable discs provides an advantage over the static mixers, the proposed solution is not applicable in food processing applications, or other liquid processing applications where the hygienic requirements are of utmost importance.

Hence, there is a need for an improved liquid product mixer which is capable of providing a turbulence depending on the liquid products flowing through the mixer, as well as being capable of providing a minimum of turbulence in non-mixing situations such as during cleaning-in-place. Moreover, there is a need for a hygienic liquid product mixer.

Summary

It is, therefore, an object of the present invention to overcome or alleviate the above described problems.

The basic idea is to provide a variable mixer having the possibility to adjust the mixing efficiency.

A further idea is to provide a variable mixer which may be arranged in a non-mixing position for minimizing the pressure drop across the mixer.

A yet further idea is to provide a variable mixer having a simple and cost effective mechanical construction, still fulfilling the necessary requirements on hygiene.

According to a first aspect, a liquid product mixer for hygienic

applications is provided. The mixer comprises a tubular portion for receiving at least two different liquid products and guiding said products when flowing from a first end to a second end of said tubular portion; at least one valve having a valve member inserted in said tubular portion between said first end and said second end, and a regulator for rotating said valve member between an idle position and a mixing position, wherein said valve member comprises a rotational axis extending between a first position and a second position, said first and second positions being arranged at different locations of the inner periphery of the tubular portion. Said rotational axis may extend through the center of said tubular portion such that said rotational axis coincides with a diameter of the tubular portion.

Said valve member may form a disc having a continuous outer periphery corresponding to the complete inner periphery of the tubular portion.

Said idle position may correspond to a position causing a minimal pressure drop across said mixer, and said mixing position may correspond to a position causing an increased pressure drop across said mixer.

Said inner periphery of said tubular portion may be circular, which is advantageous in that turbulent flow caused by said tubular portion is reduced.

Said valve member may comprise a passageway for allowing food products to pass through said valve member. Hence, the valve may never completely bock fluid flow, while additional turbulence may be caused by said passageway for increasing the mixing. Said passageway may further be arranged off center. Further, said passageway may extend from a first side and a back side of said valve member, wherein the shape of the passageway at the first side is different from the shape of the passageway at the back side.

Said valve member has a front side and a back side, wherein said front side may be curved. By providing the front side as either convex or concave, additional mixing capabilities may be achieved.

The food product mixer may further comprise at least one additional valve arranged downstream of said first valve for further increasing the mixing capabilities of the mixer.

The rotating axis of a valve member of a first valve may be rotated 70- 1 1 0 ^Q in a peripheral direction relative a valve member of a subsequently arranged valve for further increasing the turbulence.

The distance between two adjacent valves along the longitudinal axis of the tubular portion may be between once and twice the diameter of the tubular portion.

According to a second aspect, a liquid processing unit is provided. The unit comprises liquid processing equipment for transporting and treating liquid products flowing through said processing unit, and at least one liquid product mixer according to the first aspect arranged before, after, or within said liquid processing equipment.

The liquid processing unit may further comprise a sensor unit being configured to measure the mixing rate of the liquid products downstream of the liquid product mixer, and a controller configured to receive the measured mixing rate and configured to determine a corrected mixing position of the valve member, wherein said controller is configured to control said regulator according to the determined corrected mixing position in order to increase or decrease the mixing rate.

Said sensor unit may comprise at least one sensor being selected from the group consisting of: a near infrared sensor, a conductivity sensor, a viscometer, a pressure drop sensor, an ultra sonic sensor, and a turbidity sensor.

The liquid processing unit may form a part of a food processing system. According to a third aspect, a method for mixing liquid products flowing through a liquid processing unit according to the second aspect is provided. The method comprises: determining the mixing rate downstream of the mixer, comparing the determined mixing rate with a reference value, and activating a regulator of said mixer for changing the position of an associated valve member, such that the mixing rate provided by said mixer is increased or decreased.

The method may further comprise the step of determining the kind of liquid flowing through said mixer, whereby said reference value is dependent on said determined kind of liquid.

Liquid product is defined as a product being possible to pump through a product processing line. Hence, liquid product may e.g. include food products having different viscosities as well as arbitrary amount of solid content such as drinks, milk, juice, soups, puree, baby food, etc. Brief Description of Drawings

The above, as well as additional objects, features, and advantages of the present invention, will be better understood through the following illustrative and non-limiting detailed description of preferred embodiments of the present invention, with reference to the appended drawings, wherein:

Fig. 1 is an isometric view of a mixer according to an embodiment;

Fig. 2a-h are front views of a valve member of a mixer according to different embodiments;

Fig. 3a-c are side views of a valve member of a mixer according to yet further embodiments; and

Fig. 4 is a schematic view of a food processing unit according to an embodiment. Detailed Description

Starting with Fig. 1 , a mixer 10 is shown. The mixer 10 includes a tubular portion 12 extending from a first end 14 configured to receive a flow of liquid products and/or cleaning liquids, to a second end 1 6 from which the liquid product and/or cleaning liquid exits. The tubular portion has a circular cross- section. Three valves 20 are arranged in series within the tubular portion 12.

Each valve 20 includes a valve member 22 in the shape of a disc, wherein each valve member 22 is able to rotate upon activation by a regulator 24 arranged outside the tubular portion 12. The regulator 24 may e.g. include an electrical motor connected to the valve member 22 which electrical motor is configured to rotate the valve member 22 between a mixing position, i.e. when the disc of the valve member 22 at least to some extent is blocking the flow path through the tubular portion 12, and an idle position in which the disc of the valve member 22 is arranged in parallel with the longitudinal axis of the tubular portion 12 for providing a minimum of pressure drop and turbulence.

The valve member 22 is thus rotatable relative an axis 26 being perpendicular to the longitudinal axis of the tubular portion 12, why the flow of liquid products and/or cleaning liquids is diverted to an extent being dependent on the position of the valve member 22.

The valves 20 are preferably individually controlled, such that each valve 20 is associated with an individual regulator 24. However the valves 20 may also be controlled by only one regulator 24, thus requiring mechanical connections between the single regulator 24 and each one of the valves 20.

Although the regulator 24 has so far been described as an electrical motor, other regulators may also be used for the purpose of rotating the valve members 24. For example, a solenoid may be used, or other electrical, or pneumatic or mechanical means known in the art of valve regulation.

In particular embodiments, the disc of the valve member 22 has a continuous periphery corresponding to the inner periphery of the tubular portion 12. This is particularly advantageous in that there are no edges or irregular surfaces at which food product content may be trapped. Moreover, such construction of the disc facilitates cleaning of the valve 20 and the entire mixer 10 such that the requirements of a mixer arranged in a hygienic application may easily be fulfilled.

The valves 20 are arranged at a specific distance from each other, wherein the distance along the longitudinal axis of the tubular portion 12 between two adjacent valves 20 preferably is twice the diameter of the tubular portion 12 or less. Defining the diameter of the tubular portion 12 as "D", and the distance between two adjacent valves 20 as "d", two adjacent valves 20 are preferably arranged such that D < d < 2D.

As is further shown in Fig. 1 , the rotational axes of two subsequently arranged valves 20 are preferably perpendicular to each other in order to increase the mixing rate.

Liquid product and/or cleaning liquid is introduced in the mixer at the first end 14, and then flows through the mixer 10 whereby turbulence is causing the liquid products and/or cleaning liquids to blend. The first valve 20, i.e. the leftmost valve 20, is almost closed such that the disc of the valve member 22 is causing a narrow path between its outer periphery and the inner periphery of the tubular portion 12. Hence, turbulence will occur at the narrow paths which increase the mixing properties of the entire mixer. The subsequent valve 20 is arranged at a mid mixing position, such that the disc of the valve member 22 is rotated approximately 45° relative the longitudinal portion 12. Further, the rotational axis is perpendicular to the rotational axis of the first valve 20 for further increasing the mixing capabilities. The last valve 20, i.e. the rightmost valve, is held in its idle or open position thus contributing to the mixing by a very little extent. Finally, mixed liquid products and/or cleaning liquid exit at the second end 16.

Now referring to Fig. 2a-h, different embodiments of a valve member 22 are shown. For all embodiments, the valve member 22 includes at least one passageway 23 through which flowing fluids are allowed to pass.

Starting with Fig. 2a, the valve member 22 is a disc having a continuous outer periphery and a centrally aligned through hole 23a. Hence, the valve member 22 forms an annular shape.

In Fig. 2b the through hole 23b is arranged off centre.

In Fig. 2c the through hole 23c forms a semicircle located at the lower half of the disc 22.

The valve member 22 shown in Fig. 2d includes a plurality of passageways 23d, evenly distributed across the disc for allowing flowing food products and/or cleaning liquid to flow through the different passageways 23d.

Now referring to Fig. 2e the valve member 22 includes a plurality of elongated slits 23e. The slits 23e are arranged in parallel with each other.

Fig. 2f shows a further embodiment of a valve member 22, wherein two passageways 23f are provided. The two passageways 23f aligned with the outer periphery of the valve member 22. In Fig. 2g the valve member 22 comprises two symmetrically aligned passageways 23g, wherein each passageway 23g is arranged to disrupt the outer periphery of the disc such that the outer periphery of the disc no longer corresponds to the inner periphery of the tubular portion 12.

Fig. 2h shows another embodiment of a disc, wherein only one passageway 23h is arranged to change the outer periphery of the disc.

For each of the valve members 22 shown in Fig. 2a-h the rotational axis may be disposed at any angle, such that the passageways 23a-h may be oriented differently relative the flow.

In Fig. 3a the valve member shown in Fig. 2b is shown. Here, a front side of the valve member 20, i.e. side facing the first end 14 of the tubular portion 12, has a convex shape for creating a further change of the mixing capabilities of the valve 20.

A yet further embodiment is shown in Fig. 3b, showing a side view of the valve member 22 previously shown in Fig. 2d. Here, the front side of the valve member 22, i.e. the side facing the first end 14 of the tubular portion 12 is concave for changing the turbulence of the mixer.

In other embodiments, the front side and the back side of the valve member 20 may be planar, concave, or convex in any suitable combination.

Fig. 3c shows a further embodiment of a valve member 22, wherein the passageway 23a, corresponding to the passageway shown in Fig. 2a, has a diameter which varies across the valve member 22. Hence, the passageway has a conical shape for further improving or changing the mixing properties of the valve member 22.

Now referring to Fig. 4, a liquid processing unit 1 00 is shown schematically. The liquid processing unit 100 may e.g. be a food processing unit, and may form part of e.g. a dairy system. Liquid products are introduced at "A" and are transported through various liquid processing equipments 1 10. The liquid processing equipment 1 10 may be any kind of equipment for transporting or treating the liquid product, and may e.g. be a homogenizer, a clarifier, a sterilizer, a heater, a filter, etc. Downstream of the equipment 1 10 a supply 120 is provided. The supply 120 is provided for introducing a further product to be introduced into the existing flow of liquid product. A mixer 10 is arranged downstream of the supply 120 for blending the newly introduced product. The mixer 10 is constructed according to what has previously been described, and includes three valves actuated by three individual regulators 24. Typically, the flow rate through said mixer 10 is between 0,5 and 3 m/s. A sensor 130 is arranged downstream of the mixer 10 and is followed by additional liquid processing equipment 140. The additional equipment 140 may be any kind of equipment for transporting or treating the blended liquid product.

The mixing sensor 130 is configured to detect the mixing rate of the liquid product, and may be implemented as a conductivity sensor and/or a near infrared sensor as is known within the technical field of sensing characteristics of mixed liquids. Other sensors may e.g. be an ultra sonic sensor, a turbidity sensor, a viscometer, or a pressure drop sensor.

The sensor 130 is configured to calculate a value corresponding to the degree of mixing, which value is transmitted to a controller 150. The controller 150 is configured to receive the calculated value and to compare the received value with a reference table of mixing values. Preferably, the reference table is located on a remote server 1 60 and is accessible from a large number of different liquid processing units of different locations via internet. The reference table also includes instructions on optimum valve positions, such that a difference between the actual mixing rate and the desired mixing rate may be corrected by changing the position of the valves 20.

Such correction is managed by the controller 150, which upon request receives the correct valve positions from the reference table and transmits commands to each one of the regulators 24. Upon such command each regulator is activated and rotates the associated valve member 22 such that the mixing rate is changed towards the optimum value.

The controller may preferably also receive information about the kind of liquid flowing, such that adequate mixing is achieved for the particular food product. For example, the controller may be configured to rotate each of the valve members to their idle or open position when cleaning-in-place is initiated, whereby mixing is superfluous and any pressure drop across the cleaning-in- place circuit is unwanted.

The different valves 20 may be operated according to predetermined instructions. For example, only the first valve 20 is rotated to a mixing position when cream and skimmed milk is to be blended. When a low viscous additive is added, also the second valve 20 is rotated to a mixing position. In case of an additional slurry additive, also the third valve is activated and rotated to its mixing position.

The regulators 24 may have a built-in stop function, whereby an initiating command from the controller 150 results in a rotational movement from a first end position to a second end position, the first and second end positions being predetermined. Further, each regulator and the corresponding valve member 22 may be equipped with a feedback loop such that the actual position of the valve member 22 always corresponds to the requested position. Such feedback loop may be provided by means of additional sensors etc.

The invention has mainly been described with reference to a few embodiments. However, as is readily understood by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the invention, as defined by the appended claims.