WO2016170178A1

WO2016170178A1 - A filter unit, and a processing equipment comprising such filter unit

Info

Publication number: WO2016170178A1
Application number: PCT/EP2016/059130
Authority: WO
Inventors: Leif BRANDT IVERSEN; Lars MOSGAARD
Original assignee: Tetra Laval Holdings and Finance SA
Current assignee: Tetra Laval Holdings and Finance SA
Priority date: 2015-04-24
Filing date: 2016-04-25
Publication date: 2016-10-27
Anticipated expiration: 2017-10-24

Abstract

A filter unit is provided, comprising a housing (110) and a filter element (120) arranged inside the housing (110), wherein the filter unit (100) further comprises a first fluid channel (130) extending between an inlet (102) and a re-circulation outlet (104) through the filter element (120), and a second fluid channel (140), bypassing said filter element (120) and extending between said inlet (102) and a discharge outlet (106).

Description

A FILTER UNIT, AND A PROCESSING EQUIPMENT COMPRISING SUCH FILTER

UNIT

Technical Field

The present invention relates to a filter unit. More particularly, the present invention relates to a self cleaning filter unit for use in liquid product processing.

Background

Filter units are commonly used in liquid product processing in order to reduce the content of unwanted particles or substances in the liquid product. When a filter unit is connected to a liquid product processing equipment its functionality will normally degrade over time due to blocking.

One application for which filter units may be used is in in-line processes, e.g. in in-line mixers such as the Tetra Almix in-line high shear mixer. In cases where the liquid product consists of powders dissolved in liquids the mixed product will pass through a filter unit after being discharged from the mixer. Some or all parts of the liquid product will be re-circulated over the mixer. The filter unit may form part of the mixer, or it may form part of downstream equipment.

In order to avoid downtime due to malfunction of the filter unit, filtering is normally done with a filter unit consisting of double filter or strainer elements and associated instrumentation, hardware and software. The two elements are not used simultaneously, but as one filter element is blocked filtering is changed from one of the strainer or filter elements to the other. This can be done either manually or automatically, whereby the blocked element is taken out, cleaned and reinserted.

The above description of filter units provide a number of drawbacks, such as product losses, loss of hygiene, risk of scolding in case of hot mixing or cleaning, use of manpower hours, risk of blocking leading to production stop, as well as extra management.

In order to provide an improved filter unit it has been suggested to implement automatic inline cleaning of the filter or strainer element. However, such solutions have proven to require even more hardware, software and increased use of water detergents than the manual option.

In view of the above there is a need for an improved filter unit, as well as processing equipment comprising such filter unit.

Summary

An object of the present invention is to reduce the above-mentioned drawbacks of prior art filter units. An idea of the present invention is to provide a self cleaning filter unit, whereby the self-cleaning functionality is achieved by arranging a filter element inside a housing such that a first fluid channel is formed through the filter element, while a second fluid channel, bypassing the first fluid channel, is formed in the housing. The first fluid channel is in fluid communication with a re-circulation path, while the second fluid channel is in fluid communication with downstream equipment. Since there is no need for adapting the flow through the re-circulation path to downstream equipment, this flow may be increased to a level ensuring self cleaning of the filter unit.

According to a first aspect, a filter unit is provided. The filter unit comprises a housing and a filter element arranged inside the housing, wherein the filter unit further comprises a first fluid channel extending between an inlet and a re-circulation outlet through the filter element, and a second fluid channel, bypassing said filter element and extending between said inlet and a discharge outlet.

The housing may have a cylindrical shape, or other elongated shapes having end surfaces, e.g. in the form of a circle, ellipse, etc, and sidewalls extending between said end surfaces. The re-circulation outlet may be arranged at an end of the housing, and the discharge outlet may be arranged at the sidewall of the housing.

In an embodiment, the re-circulation outlet is in fluid communication with the inlet.

According to a second aspect a processing unit for liquid products is provided. The processing unit comprises a liquid product processing path, and a filter unit according to the first aspect arranged in said processing path such that the recirculation outlet of said filter unit is in fluid communication with the processing path upstream the inlet of the filter unit.

The processing unit may comprise a re-circulation pump arranged upstream the inlet of the filter unit.

The processing unit may comprise an exit pump arranged downstream the discharge outlet.

The processing unit may further comprise a flow control valve arranged downstream said re-circulation outlet, and/or a flow control valve arranged

downstream said discharge outlet.

In an embodiment, the liquid product processing path comprises a mixing unit. According to a third aspect a method for filtering a flow of liquid product is provided. The method comprises the step of feeding the liquid product through a filter unit having a housing and a filter element arranged inside the housing, whereby a first part of the liquid product is transported through a first fluid channel extending between an inlet and a re-circulation outlet through the filter element, and a remaining part of the liquid product is transported through a second fluid channel, bypassing said filter element and extending between said inlet and a discharge outlet.

In an embodiment, the first part of the liquid product flowing through the first fluid channel is re-circulated over the filter unit.

Brief Description of Drawings

Preferred embodiments of the present invention will now be described in greater detail herein below with reference to the accompanying drawings, in which:

Fig.1 is a schematic view of a processing equipment having a filter unit according to an embodiment;

Fig. 2 is a schematic cross-sectional view of a filter unit according to an embodiment;

Figs. 3a and 3b shows part of a filter unit according to an embodiment; and Fig. 4 is a schematic view of a method according to an embodiment.

Detailed Description

Starting with Fig. 1 a processing equipment for liquid products in the form of a mixing unit 10 is shown. The mixing unit 10 is preferably arranged in a liquid processing line suitable for processing liquid products, such as liquid food products like milk, juices, soups, yoghurts, infant formula, soy, sauces, fortified milks, etc. For this, the mixing unit 10 comprises a liquid product inlet 1 1 in fluid communication with a mixing vessel 12. The mixing vessel 12 has a liquid product outlet 13 for transporting mixed liquid product further downstream. Additional inlets may be provided at the vessel 12 for introducing additives, such as particles etc.

As shown in Fig. 1 the liquid product outlet 13 may comprise a pump 14 which is provided to draw liquid product out from the vessel 12, as well as to provide a mixing action. Hence, the pump 14 may be a high shear rotor-stator pump. The liquid product outlet 13 is further connected to a filter unit 100, which is shown in further detail in Fig. 2.

The filter unit 100 is constructed to allow a flow of liquid product to enter an inlet 102 of the filter unit 100. A re-circulation outlet 104 of the filter unit 100 allows liquid product to exit the filter unit 100 and return to the mixing vessel 12 via a recirculation channel 15, while a discharge outlet 106 of the filter unit 100 allows liquid product to exit the filter unit 100 for transport to downstream processing equipment (not shown).

The liquid product inlet 1 1 , the mixing vessel 12, the liquid product outlet 13, and the re-circulation channel 15 forms a liquid product processing path 20. Hence, the filter unit 100 is arranged in said processing path 20 such that the re-circulation outlet 104 of the filter unit 100 is in fluid communication with the processing path 20 upstream the inlet 102 of the filter unit 100. The pump 14, provided at the discharge outlet 13, thus forms a re-circulation pump.

As can be seen in Fig. 1 the mixing unit 100 further comprises an exit pump

30 provided downstream the discharge outlet 106 of the filter unit 100, in a discharge channel 150 that is connected to the discharge outlet 106. The discharge channel 150 may also referred to as a second fluid channel 140. The exit pump 30 is preferably arranged in series with a flow control valve 40 (see Fig. 2). Also, a flow control valve 1 6 may be provided in the re-circulation channel 15, i.e. between the re-circulation outlet 104 of the filter unit 100 and the vessel 12. The flow control valve 40 may in some embodiments be replaced by a flowmeter and a speed control (VSD) of the exit pump 30.

Now turning to Fig. 2 the filter unit 100 is shown. From the left, liquid product enters the interior of a housing 1 10. Preferably, the housing 1 10 has a cylindrical shape, and the re-circulation outlet 104 is arranged at an end of the housing 1 10 while the discharge outlet 106 is arranged at the sidewall of the housing 1 10.

The liquid product is transported through the housing 1 10, and some part of the liquid product will exit through the discharge outlet 106. The remaining part of the liquid product will flow through a filter element 120, such as a membrane or similar strainer element before it is transported back to the vessel 12 via the re-circulation channel 15. The amount of liquid product being re-circulated will be determined by the operation of the re-circulation pump 14, the exit pump 30, and the operation of the flow control valves 1 6, 40; should the flow control valve 40 be fully closed all liquid product will be re-circulated over the filter element 120.

The flow control valve 1 6, arranged in the re-circulation channel 15, may be particularly advantageous for some liquid products, such as high viscous products, to ensure flow through the filter element 120. The flow control valve 1 6 is used to create a pressure drop to ensure the required flow through the filter element 120.

As can be seen in Fig. 2, the filter unit 100 comprises a first fluid channel 130 extending between the inlet 102 and the re-circulation outlet 104 through the filter element 120, and the second fluid channel 140, bypassing said filter element 120 and extending between said inlet 102 and the discharge outlet 106.

As the filter element 120 is mounted inside the housing 1 10 all liquid product has to pass through the housing 1 10 to exit into the re-circulation channel 15.

However, all liquid product will not need to pass through the filter element 120 at the speed at which the downstream equipment can receive the product. Instead, the flow over the filter element 120 will be equal to the re-circulation rate of the mixing unit 10, and mixed liquid product that is to exit the filter unit 100 will be the only liquid product that flows by the speed of the downstream equipment. As the flow through the re-circulation channel 15, and hence through the filter element 120, is 3-10 times higher than the flow of the downstream equipment a self cleaning action is provided. Hence the material of the filter element 120 is always kept clean. Thus, a flow of fluid through the first fluid channel 130 is at least 3 times, or at least 5 times, or at least 10 times higher than a fluid flow through the second fluid channel 140. This means that a fluid flow though the re-circulation channel 15 is at least 3 times, or at least 5 times, or at least 10 times higher than a fluid flow through the discharge channel 150.

The filter element 120 may for this purpose be provided with slots, or holes, whereby the shape of the slots or holes in the filter element 120 are specifically constructed to promote this. The filter unit 100 will consequently run much longer than conventional systems, and ideally longer than associated processing equipment so that the filter unit 100 is no longer the bottleneck with regards to time between cleaning.

The cut of particle size may be well defined by the different slot or hole sizes, which is chosen depending on product and requirements. In Figs. 3a and 3b parts of a filter unit 100 are shown. As can be seen in Fig. 3a, the housing 1 10 encloses a filter element 120 shown in Fig. 3b. The filter element 120 has a plurality of slots 122.

The self-cleaning functionality is thus achieved by arranging the filter element inside the housing 1 10 such that the first fluid channel 130 is formed through the filter element 120, while the second fluid channel 140, bypassing the first fluid channel 130, is formed in the housing 1 10. The first fluid channel 130 is in fluid

communication with the re-circulation path 15, while the second fluid channel 140 is in fluid communication with downstream equipment. Since there is no need for adapting the flow through the re-circulation path 15 to downstream equipment, this flow may be increased to a level ensuring self cleaning of the filter unit.

Now turning to Fig. 4 a method 200 according to an embodiment will be described. The method 200 is performed for filtering a flow of liquid product, and comprises the step 202 of feeding the liquid product through a filter unit having a housing and a filter element arranged inside the housing. A first part of the liquid product is transported through a first fluid channel extending between an inlet and a re-circulation outlet through the filter element, and a remaining part of the liquid product is transported through a second fluid channel, bypassing said filter element and extending between said inlet and a discharge outlet.

The method may also comprise the step 204 in which the first part of the liquid product flowing through the first fluid channel is re-circulated over the filter unit.

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.

Claims

1 . A filter unit, comprising a housing (1 10) and a filter element (120) arranged inside the housing (1 10), wherein the filter unit (100) further comprises a first fluid channel (130) extending between an inlet (102) and a re-circulation outlet (104) through the filter element (120), and a second fluid channel (140), bypassing said filter element (120) and extending between said inlet (102) and a discharge outlet (106).

2. The filter unit according to claim 1 , wherein said housing (1 10) has a cylindrical shape, and wherein said re-circulation outlet (104) is arranged at an end of the housing (1 10), and said discharge outlet (106) is arranged at the sidewall of the housing (1 10).

3. The filter unit according to claim 1 or 2, wherein said re-circulation outlet

(104) is in fluid communication with the inlet (102) via a re-circulation channel (15).

4. A processing unit for liquid products, comprising a liquid product processing path (20), and a filter unit (100) according to any one of claims 1 -3 arranged in said processing path (20) such that the re-circulation outlet (104) of said filter unit (100) is in fluid communication with the processing path (20) upstream the inlet (102) of the filter unit (100).

5. The processing unit according to claim 4, wherein said processing unit (10) comprises a re-circulation pump (14) arranged upstream the inlet (102) of the filter unit (100).

6. The processing unit according to claim 4 or 5, wherein said processing unit (10) comprises an exit pump (30) arranged downstream the discharge outlet (106).

7. The processing unit according to any one of claims 4-6, further comprising a flow control valve (1 6) arranged downstream said re-circulation outlet (104).

8. The processing unit according to any one of claims 4-7, further comprising a flow control valve (40) arranged downstream said discharge outlet (106).

9. The processing unit according to any one of claims 4-8, wherein the liquid product processing path (20) comprises a mixing unit (12, 14).

10. A method for filtering a flow of liquid product, comprising the step of: feeding the liquid product through a filter unit having a housing and a filter element arranged inside the housing, whereby a first part of the liquid product is transported through a first fluid channel extending between an inlet and a recirculation outlet through the filter element, and a remaining part of the liquid product is transported through a second fluid channel, bypassing said filter element and extending between said inlet and a discharge outlet.

1 1 . The method according to claim 10, wherein the first part of the liquid product flowing through the first fluid channel is re-circulated over the filter unit.