WO2016087359A1

WO2016087359A1 - Methods and arrangements for reduced water and energy consumption

Info

Publication number: WO2016087359A1
Application number: PCT/EP2015/078039
Authority: WO
Inventors: Johan Persson
Original assignee: Tetra Laval Holdings & Finance S.A.
Priority date: 2014-12-02
Filing date: 2015-11-30
Publication date: 2016-06-09

Abstract

A method for recycling water in a processing system is presented. The method comprises collecting water comprising product residues from the processing system, subjecting the water comprising product residues for filtration such that filtered water is formed, wherein the filtered water having at least part of said product residues removed, and feeding said filtered water back to said processing system.

Description

Methods and arrangements for reduced water and energy consumption

Technical Field

Methods and apparatuses related to the field of processing of liquid food processing are presented. More particularly, methods and apparatuses for food processing being efficient in terms of water and energy consumption are presented.

Background

In order to save costs and the environment food producers around the world are seeking for alternatives to make their processing systems more efficient in terms of energy consumption as well as resource usage. A number of initiatives have been made in order to provide more efficient processing equipment. For instance, it has been presented regenerative tubular heat exchangers arranged to transfer energy from outgoing product to incoming product such that the outgoing product is cooled down and the incoming product is pre-heated. It has also been presented efficient homogenizing devices providing for that less energy is needed for homogenizing food products.

In addition to the efforts made for making components of a food processing line more efficient, efforts have also been made for assuring that the energy consumption on a plant level is kept low. For instance, excess heat generated from the food processing system may be used for heating a building in which the system is placed.

However, even though efforts have been made, there is still a need for more energy efficient food processing systems, especially in terms of energy consumption and water usage. Summary

Accordingly, the methods and apparatuses described herein preferably seeks to mitigate, alleviate or eliminate one or more of the above-identified deficiencies in the art and disadvantages singly or in any combination and solves at least the above mentioned problems.

According to a first aspect it is provided a method for recycling water in a processing system, said method comprising collecting water comprising product residues from said processing system, subjecting said water comprising product residues for filtration such that filtered water is formed, said filtered water having at least part of said product residues removed, feeding said filtered water back to said processing system.

The method may further comprise determining a concentration of said product residues in said water before subjecting said water for filtration, and if said concentration is above a threshold, directing said water to a drain, else, subjecting said water for said filtration.

At least one sensor may be used for determining said concentration of said product residues.

The sensor may be selected from a group consisting of a turbidity sensor and a conductivity sensor.

The water comprising product residues may be selected from the group consisting of used cooling water from a homogenizer being part of the processing system, used condensate water from said homogenizer, used condensate from a steam trap being part of the processing system, used condensate from a pump being part of said processing system and used seal water from said processing system.

The water comprising product residues may be filtered by using a reverse osmosis filter arrangement.

The water comprising product residues may further comprise steam boiler chemicals and said filtered water may comprise substantially the same concentration of steam boiler chemicals as said water comprising product residues. The method may further comprise, if said concentration is above a threshold, transferring a notification that a seal in said processing system is likely to be broken to a monitoring system.

According to a second aspect it is provided a water recycling

arrangement comprising a collecting tank provided with at least one inlet for receiving water from at least one component of a food processing system, said water comprising product residues, and a filtration arrangement arranged for filtering said water such that filtered water is formed and fed back to said food processing system, said filtered water having at least part of said product residues removed.

The arrangement may further comprise at least one sensor arranged for determining a concentration of said product residues in said water before subjecting said water for filtration, and a valve arranged for directing said water to a drain if said concentration is above a threshold, else, directing said water to said filtration arrangement.

The at least one sensor may be selected from a group consisting of a turbidity sensor and a conductivity sensor.

The filter arrangement may be a reverse osmosis filter arrangement. The water comprising product residues may further comprise steam boiler chemicals and said filtered water comprises substantially the same concentration of steam boiler chemicals as said water comprising product residues.

The arrangement may further comprise, if said concentration is above a threshold, transferring a notification that a seal in said processing system is likely to be broken to a monitoring system.

According to a third aspect it is provided a processing system

comprising a water recycling arrangement according to the second aspect. Brief description of the 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 illustrates a general example of a food processing system.

Fig 2 illustrates an arrangement for recycling water in a food

processing system.

Detailed description of preferred embodiments

Fig 1 generally illustrates an example of a system 100 for UHT treatment of milk using a direct steam injection device. Instead of using a direct steam injection device, other types of UHT heat treatment devices can be used as well, such as steam infusion devices or tubular heat exchangers only to mentioned a few.

There are generally two different types of systems for UHT treatment of milk, direct UHT sytems and indirect UHT systems. The direct UHT systems could for instance be the illustrated steam injection based UHT system in which hot steam is injected to the milk in order to provide for that this is rapidly heated to about 140 degrees C and kept at this tempeature for a few seconds before it is cooled down rapidly. In order to cool down the milk and at the same time remove steam a vacuum vessel, also known as a flash vessel, can be used. Alternatively, the direct UHT system could be a so-called steam infusion based UHT system in which the milk is heated rapidly by injecting the milk into a steam chamber, instead of injecting the steam into the milk.

An indirect UHT system can use a tubular heat exchanger for heating the milk to about 140 degrees C. An advantage of indirect systems compared to direct systems is that less energy is needed. A disadvantage is however that the milk is not as rapidly heated as in the direct UHT system, which has the effect the taste of the milk is to a higher degree is affected in the indirect UHT system compared to the direct UHT system. Referring to the example illustrated in fig 1 , milk is transferred into the system 100 to a balance tank 102. The balance tank 102 serves the purpose of balancing an uneven flow of milk. From the balance tank 102 the milk can be transferred via a feed pump 104 to a plate heat exchanger 106, or alternatively a tubular heat exchanger, for pre-heating the milk. The milk can at this stage be pre-heated to about 80 degrees C, i.e. above pasteurization temparature, in order prevent growth of unwanted microorganisms. As illustrated, the plate heat exchanger 106 can be divided in different sections. In order to heat the milk hot water may be used as a heat transfer media. Similarly, in order to cool down the milk cold water may be used as heat transfer media. Although not illustrated in fig 1 , the plate heat exchanger 106 may be a so-called regenerative plate heat exchanger using milk in a late stage of the process to be cooled down for heating milk in an early stage of the process to be heated. An advantage of this is that the energy

consumption can be reduced.

As can be readily understood by the skilled person in the art, the system 1 00 illustrated in fig 1 is only one out of many different possibilities when designing a UHT plant. For instance, as indicated above, different types of heat exchangers can be used. Further, even though milk is given as example other food products may be treated as well.

In the particular example illlustrated in fig 1 , after having pre-heated the milk this is transferred to a steam injection head in which hot steam is injected into the milk. The steam injection head may be a so-called ring nozzle steam injector used, for instance, in the solution Tetra Therm Aseptic VTIS™ marketed by Tetra Pak.

In order to make sure that the milk is kept at a temperature above for 135 degrees C and at least 1 second, or any other combination of

temperature and time decided by the operator or stipulated by food safety regulation, a holding tube 1 10 may be used.

After being fed from the holding tube 1 10 the UHT treatment of the milk is finalized and the milk is transferred to a vacuum vessel 1 12, or flash vessel, in order to flash cool the milk. The reason for flash cooling the milk is in order to make sure that steam introduced by the steam injection head 108 is removed from the milk. In order to control the amount of vapour, or steam, that is removed a vacuum pump 1 14 may be used.

After having flash cooled the milk, this can be fed via a centrifugal pump 1 1 6 to a homogenizer 1 18 arranged for aseptically homogenizing the milk. Thereafter, the milk may pass through a different section of the plate heat exchanger 104 before being transferred to an aseptic tank 120 or a filling machine 122, such as Tetra Pak A6™ marketed by Tetra Pak or other filling machine arranged to fill bottles, such PET bottles, carton bottles or any other package.

In order to clean the system 100 an Cleaning In Place (CIP) tank 124 may be used.

Water and steam are however used in other places of the system 100 as well. For instance, in the homogenizer 1 18 cooling water may be used for cooling the endinge and steam may be sprayed onto pistons moving back and fourth in order to provide for that no unwanted microorganisms come in contact with the product. The cooling water is in many cases fed to the drain after served its purpose. The same is often the case for the steam after this has been condensated into a condensate.

In the same way condensate from steam caught in steam traps, condensate from steam used in pumps, e.g. vacuum pumps, seal water etc are usually fed to the drain.

Fig 2 illustrates an arrangement 200 for recycling cooling water, condensate, seal water etc. The arrangement 200 may be part of a system for liquid food processing, such as the system 100 illustrated in fig 1 .

The arrangement 200 can comprise a collecting tank 202 for collecting water, e.g. cooling water from a homogenizer, condensate water from the homogenizer, condensate from steam traps, condensate from pumps and seal water from different parts of the system.

In order to be able to recycle water collected in the collecting tank 202 this needs to be treated such that unwanted food residues and other unwanted material are removed from the water. In order to do so the water collected in the collecting tank 202 can be fed via a pump 204 to a filter arrangement 206. After having been filtered the water can be fed to a storage tank 208 arranged to store the water before this is transferred to the homogenizer for being used as cooling water, or to a pump for being used as seal water, or to a steam boiler for generating steam to be used for spraying the pistons in the homogenizer or for being used in a steam injection apparatus, such as Tetra Therm Aseptic VTIS™, for heat treating a food product, or for being used in pumps, etc.

In order to make sure that running time between cleaning for the filter arrangement 206 is kept at a high level, sensors may be placed between the collecting tank 202 and the storage tank 208. If it can be determined, by using e.g. appropriate software, that based on the output from the sensors that the water fed from the collecting tank 202 is containing a concentration of food residues above a pre-set threshold, i.e. there is a risk that the filter

arrangement 206 would quickly clog, the water can by using a valve 214 be directed to the drain instead of the filter arrangement 206.

Different types of sensors may be used for different products. For instance, a turbidity sensor may be used for transparent or semi-transparent products. For low transparency products, such as juice, a conductivity sensor can be used. Further, a combination of different types of sensors can be used.

If a high product concentration is detected by using the sensors this may also be signalled to a monitoring system as an indication that a seal may be broken and should be replaced.

The filter arrangement 206 may be a reverse osmosis (RO) filter arrangement, but other types of filters may be used as well. Which filter to use is dependent on the product being treated and the temperature at which the filtration is to be performed.

By collecting, filtering and re-using the water in the food processing system, water usage can be reduced. Since water treatment, that is, treating water such that this can be used in the food processing system, is consuming considerable amounts of energy, another advantage, apart from reducing water usage, is that the energy efficiency of the system is improved.

In addition to the advantages mentioned above less steam boiler chemicals are needed. More particularly, when boiling water in order to form steam that can be used for instance in a steam injection apparatus, steam boiler chemicals can be added. The steam boiler chemicals may have one or more of the effects that the pH levels are maintained, that foaming is prevented, that oxygen is consumed such that corrosion can be avoided, that dissolved solids are precipitated before they are formed on steam-generating surfaces, and to remove formed precipitates from the steam-generating surfaces. Since the steam boiler chemicals are not removed, or at least to only a certain extent is removed, in said filter arrangement, less or no additional steam boiler chemicals are needed in the filtered water fed back to the system.

Even though the illustrated systems and the examples given are liquid food processing systems, it should be understood that the content of this patent application may be applicable to other kinds of processing systems as well, e.g. pharmaceutical processing systems and cosmetics processing systems.

The invention has mainly been described above with reference to a few embodiments. However, as is readily appreciated 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 patent claims.

Claims

1 . A method for recycling water in a processing system, said method comprising

collecting water comprising product residues from said processing system,

subjecting said water comprising product residues for filtration such that filtered water is formed, said filtered water having at least part of said product residues removed,

feeding said filtered water back to said processing system.

2. The method according to claim 1 , said method further comprising determining a concentration of said product residues in said water before subjecting said water for filtration, and

if said concentration is above a threshold, directing said water to a drain, else, subjecting said water for said filtration.

3. The method according to claim 2, wherein at least one sensor is used for determining said concentration of said product residues.

4. The method according to claim 3, wherein said sensor is selected from a group consisting of a turbidity sensor and a conductivity sensor.

5. The method according to any of the preceding claims, wherein said water comprising product residues is selected from the group consisting of used cooling water from a homogenizer being part of the processing system, used condensate water from said homogenizer, used condensate from a steam trap being part of the processing system, used condensate from a pump being part of said processing system and used seal water from said processing system.

6. The method according to any of the preceding claims, wherein said water comprising product residues is filtered by using a reverse osmosis filter arrangement.

7. The method according to any of the preceding claims, wherein said water comprising product residues further comprises steam boiler chemicals and said filtered water comprises substantially the same concentration of steam boiler chemicals as said water comprising product residues.

8. The method according to any of the claims 2-7, further comprising if said concentration is above a threshold, transferring a notification that a seal in said processing system is likely to be broken to a monitoring system.

9. A water recycling arrangement comprising

a collecting tank provided with at least one inlet for receiving water from at least one component of a food processing system, said water comprising product residues,

a filtration arrangement arranged for filtering said water such that filtered water is formed and fed back to said food processing system, said filtered water having at least part of said product residues removed.

10. The arrangement according to claim 9, said arrangement further comprising

at least one sensor arranged for determining a concentration of said product residues in said water before subjecting said water for filtration, and a valve arranged for directing said water to a drain if said concentration is above a threshold, else, directing said water to said filtration arrangement.

1 1 . The method according to claim 10, wherein said at least one sensor is selected from a group consisting of a turbidity sensor and a conductivity sensor.

12. The arrangement according to any of the claims 9 to 1 1 , wherein said water comprising product residues is selected from the group consisting of used cooling water from a homogenizer being part of the processing system, used condensate water from said homogenizer, used condensate from a steam trap being part of the processing system, used condensate from a pump being part of said processing system and used seal water from said processing system.

13. The arrangement according to any of the claims 9 to 12, wherein said filter arrangement is a reverse osmosis filter arrangement.

14. The arrangement according to any of the claims 9 to 13, wherein said water comprising product residues further comprises steam boiler chemicals and said filtered water comprises substantially the same concentration of steam boiler chemicals as said water comprising product residues.

15. The arrangement according to any of the claims 10 to 14, further comprising

if said concentration is above a threshold, transferring a notification that a seal in said processing system is likely to be broken to a monitoring system.

16. A processing system comprising a water recycling arrangement according to any one of the claims 9 to 15.