Plant and method for concentrating a liquid food product

Abstract

Concentration plant (100) for a liquid food product, comprising: - a concentrator apparatus (10); - an entry line (20) of entry to the concentrator apparatus (10) for the food product to be treated; - an exit line (30) of exit from the concentrator apparatus (10) for the treated food product, - a bypass line (40) that puts the exit line (30) in selective fluid communication with the entry line (20); - a control unit (50) configured to, in response to a first signal, enable communication from the exit line (30) to the entry line (20) through the bypass line (40) such that at least a part of the treated food product flows into the entry line (20).

Description

[0001] DESCRIPTION

[0002] PLANT AND METHOD FOR CONCENTRATING A LIQUID FOOD PRODUCT

[0003] Technical field

[0004] The present invention relates to a plant and a method for concentrating a liquid food product, such as fruit, vegetable and similar juices, purees and creams. The present invention finds particular application for the concentration of tomato juice.

[0005] Prior art

[0006] For the concentration of the juices, multi-effect or multi-stage concentration plants are normally used, in which the concentration takes place by evaporation.

[0007] Multi-effect or multi-stage concentration plants are normally made with different types of operation: in particular, forced circulation evaporators and falling film evaporators.

[0008] In general, each concentration effect or stage has a vertical tube bundle in which a plurality of pipes are arranged whose ends are keyed on two parallel plates, respectively an upper and a lower plate, so that the upper ends of the pipes open into a product entry zone while their lower ends open into a lower zone of the evaporator, said separation chamber, in which the product loses water by self-evaporation (flash), by cooling down, and from which the product exits to be sent to subsequent processing.

[0009] The pipes are enclosed in a shell, generally cylindrical and delimited by the two said parallel plates, inside which a heating fluid circulates that is generally vapour; the outer surface of the pipes is lapped by the heating fluid while their inner surface is traversed by the product which, upon heating, loses water in the form of vapour and thus concentrates.

[0010] In forced circulation evaporators the product completely fills the inside of the pipes, while, in the case of falling film evaporators, the product forms a thin falling film on the inside of the pipes. In these plants, the tube bundle can be divided into two or more sectors that are arranged in series so that the product descending from the first sector and arriving in the separation chamber is returned to the top of the tube bundle through a down pipe and made to descend into the following sectors. The product is then extracted from the separation chamber once it has passed through the last sector. Such plants, and their operation, are in any case known in the art.

[0011] The solutions known in this context, however, are affected by the main drawback that each solution must be designed and sized specifically for the specific needs of the application. This complicates operations and lengthens delivery times.

[0012] Aim of the invention

[0013] In this context, the task of the present invention is to provide a plant and a method for concentrating a liquid food product that are versatile and easily adaptable to different application needs.

[0014] Brief description of the drawings

[0015] Further characteristics and advantages of the present invention will appear clearer from the indicative, and therefore non-limiting, description of an embodiment of a plant and a method for concentrating a liquid food product.

[0016] Such a description will be set out below with reference to the accompanying drawings, which are provided solely for illustrative and therefore non-limiting purposes, in which:

[0017] - figures 1 , 2 and 3 illustrate a schematic view of a plant for concentrating a liquid food product, according to the present invention, respectively in a first, a second and a third operating mode;

[0018] - figure 4 illustrates a part (heat exchanger of the concentrator) of the plant of figure 1 , 2 and 3, in a schematic view, from above and partially sectioned.

[0019] Detailed description of preferred embodiments of the invention With reference to the figures, number 100 indicates a plant for concentrating a liquid food product.

[0020] The plant 100 comprises a concentrator apparatus 10. Preferably, the concentrator 10 is of the multi-stage type. Alternatively, the concentrator 10 is of the multi-effect type. While the stages are all at the same temperature, the effects are at different temperatures. The concentrator 10 employed in the present invention can be of any type known to a person skilled in the art, without affecting the characteristics, as well as the advantages of the present invention.

[0021] An exemplary description of an embodiment of a concentrator 10 usable in the present invention will be given below.

[0022] Preferably, the concentrator apparatus 10 comprises an outer tubular shell 2. Inside there is provided a heat exchanger 1 , in which a heating fluid circulates. Preferably, the heat exchanger 1 is an evaporator of the type known as multi-stage “falling film” with mechanical vapour recompression. The heat exchanger 1 is defined by an upper plate 3 and a lower plate 4 on which the open ends of a bundle of down pipes 5 are fixed, in which the product to be treated circulates, so that the upper ends of the down pipes 5 open into an entry zone 6 of the heat exchanger 1 in which the product is distributed, and the lower ends of the down pipes 5 open into a bottom zone which is a separation chamber 7 of the heat exchanger 1. In particular, the down pipes 5 are divided into a plurality of sectors 8 in which the product circulates in succession and which define a corresponding plurality of stages, typical terminology of the sector.

[0023] In particular, the product enters a first stage characterized by a certain number of down pipes. The product is distributed on the surface of the pipes while the vapour separated from the product circulates in the inner part of the pipe. Upon arrival at the first sector of the separation chamber, the vapour is separated and sucked by a compressor which compresses it with a polytropic compression thus increasing its temperature. From the first sector of the chamber, the product is pumped into the subsequent sectors with an increasingly smaller number of pipes.

[0024] The heat exchanger 1 comprises at least one pipe 9 for the ascent of the product for each sector 8.

[0025] The plant 100 comprises an entry line 20 of entry to the concentrator apparatus 10 for the product to be treated. Preferably, on the entry line 20 there is a tank 21 for product to be treated.

[0026] The plant 100 comprises an exit line 30 of exit from the concentrator apparatus 10 for the treated product. Preferably, a tank 31 for the treated product is present on the exit line 30.

[0027] The plant 100 comprises a bypass line 40 having extent between the exit line 30 and the entry line 20 to allow the product to pass from one line to another without crossing the concentrator 10. In other words, the bypass line 40 is in parallel with the concentrator 10.

[0028] The bypass line 40 puts in selective fluid communication the exit line 30 with the entry line 20. “Selective” means that communication through the bypass line can be enabled or interrupted as needed.

[0029] Preferably, the bypass line 40 originates from the exit line 30 upstream of the tank 31. Alternatively, the bypass line 40 originates from the exit line 30 downstream of the tank 31 .

[0030] Preferably, the bypass line 40 originates from the entry line 20 downstream of the tank 21. Alternatively, the bypass line 40 originates from the entry line 20 upstream of the tank 21 .

[0031] The plant 100 comprises a control unit 50 configured to, in response to a first signal, enable communication from the exit line 30 to the entry line 20 through the bypass line 40. In this way, at least a part of the treated product flows from the exit line 30 along the bypass line 40 and into the entry line 20.

[0032] By "enabling communication from the exit line 30 to the entry line 20" is meant that it acts on valve means in such a way that the flow of product is allowed exclusively from the exit line 30 towards the entry line 20, that is, it is prevented in the opposite direction.

[0033] In particular, the first signal to which reference is made is a valve opening signal, which allows the product flow to be led along the bypass line 40 into the entry line 20. This first signal can be generated manually (for example, an operator selecting an operating mode from a PLC) or automatically based on a certain detected parameter (for example, the flow rate at the entry or the degree of concentration at the exit).

[0034] In particular, the enabling of the communication by means of the bypass line 40 can take place at a first condition of the plant 100, in which the product flow rate along the entry line 20 assumes a value lower than a first predefined value. This first condition is known as insufficient flow rate or “Extra Brix”. The amount of missing flow rate is thus taken from the exit line 30 and brought into the entry line 20 through the bypass line 40.

[0035] In fact, the concentrator 10 is sized in its components with respect to a value or a range of values of process flow rate, which ensure the correct feeding condition for the pipes. Outside this range, the concentrator 10 works inefficiently, in particular a fundamental parameter is not respected, known in the sector as “liquid feed rate” which is the product flow rate per unit length of the circumference of the pipe. For “liquid feed rates” that are too high, the exchange coefficient is reduced, whereas for “liquid feed rates” that are too low, the pipe risks drying out.

[0036] The possibility of integrating the missing flow rate by means of the bypass line 40 allows this problem to be solved without structurally modifying the concentrator 10. In other words, the plant 100 becomes independent of the process flow rate.

[0037] The mixing of already treated product (which has a higher Brix (°Bx) value) with product to be treated results in an increase in the average °Bx of the product entering the concentrator. This working mode allows to have at the exit a higher Brix value for the products that need it.

[0038] According to one embodiment, the plant 100 comprises product flow rate transfer means 60. The plant 100 is configurable in at least a first standard operating mode and a second operating mode.

[0039] The first operating mode is to be used in standard flow rate conditions (which are established in the values on a case-by-case basis depending on the sizing of the plant). In this mode, the bypass line 40 and the transfer means 60 are inactive. The product to be treated flows along the entry line 20, is treated in the concentrator 10, in particular it runs through all the stages, and then exits along the exit line 30.

[0040] Let’s consider the plant diagram 100 in figure 1. Let’s assume that the process flow rate on the entry line 20 falls within the standard flow rate values for the concentrator 10. In this case, since the concentrator 10 works under standard conditions, communication from the exit line 30 to the entry line 20 through the bypass line 40 is disabled. The product flows along the entry line 20, is treated in the concentrator 10, in particular it circulates in succession in all stages and exits the exit line 30.

[0041] The second operating mode can instead be used with the first condition described above, i.e. when the plant 100 is in an insufficient flow rate condition at the entry. The second operating mode provides that communication is enabled from the exit line 30 to the entry line 20 through the bypass line 40. The transfer means 60 operate to make at least a part of the treated product flow from the exit line 30 to the entry line 20.

[0042] In this case, the transfer means 60 may for example comprise a pump on the exit line 30 or on the bypass line 40, operative to make the product flow in the specified direction.

[0043] Let’s consider the plant diagram 100 in figure 2. Let’s assume for example that the standard flow rate for the concentrator 10 is 100 t / h. By way of example, let’s assume that the process flow rate on the entry line is 75 t / h, therefore it is insufficient with respect to the standard flow rate. The plant 100 is therefore configured in the second operating mode, whereby communication from the exit line 30 to the entry line 20 through the bypass line 40 is enabled so that the missing flow rate mixes with the product flow rate in the entry line 20, restoring a process flow rate around the standard flow rate.

[0044] This also entails an increase in the final Brix value at the exit as well as an increase in the Brix value in the product entering the concentrator 10. In fact, the product already treated has a Brix value greater than the product to be treated and mixing a part of the product already treated with the product to be treated, results in a product with an increased Brix value compared to the first operating mode.

[0045] For example, the product to be treated on the entry line 20, upstream of the connection with the bypass line 40, is at 5 °Bx, while the product already treated on the exit line 30 is at 10.7 °Bx. It follows that the product to be treated, mixed with a part of already treated product, enters the concentrator 10 at 6.4 °Bx.

[0046] According to one embodiment, the control unit is also configured to, in response to a second signal, enable communication from the entry line 20 to the exit line 30 through the bypass line 40. In this way, at least a part of the product to be treated flows from the entry line 20 along the bypass line 40 and into the exit line 30.

[0047] By "enabling communication from the entry line 20 to the exit line 30" is meant that it acts on valve means in such a way that the flow of product is allowed exclusively from the entry line 20 towards the exit line 30, that is, it is prevented in the opposite direction.

[0048] Like the first signal, also the second signal is a valve opening signal, which allows the product flow to be led into the exit line 30.

[0049] In particular, the second signal may be identifying a second condition in which the product flow rate along the entry line 20 assumes a value higher than a second predefined value, greater than the first. This second condition is known as excess flow rate or “Extra Flow”. The amount of extra flow rate (with respect to the sizing of the concentrator) is taken from the entry line 20 and brought into the exit line 30 through the bypass line 40. According to one embodiment, the plant 100 is configurable in at least a third operating mode, which can be used with the second condition described above, i.e. when the plant 100 is in a condition of extra flow rate at the entry. The third operating mode that provides for communication to be enabled from the entry line 20 to the exit line 30 through the bypass line 40, i.e. in the opposite direction to that provided for the second operating mode. The transfer means 60 operate to make at least a part of the product to be treated to flow from the entry line 20 to the exit line 30, preventing it from being treated in the concentrator 10.

[0050] In this case, the transfer means 60 may for example comprise a pump on the entry line 20 or on the bypass line 40, operative to make the product flow in the specified direction.

[0051] Let’s consider the plant diagram 100 in figure 3. Let’s assume for example that the standard flow rate for the concentrator 10 is 100 t / h. By way of example, let’s assume that the process flow rate on the entry line is 125 t / h, therefore it is in excess with respect to the standard flow rate. The plant 100 is therefore configured in the third operating mode, whereby communication from the entry line 20 to the exit line 30 through the bypass line 40 is enabled so that the extra flow rate is mixed with the flow rate of product already treated in the exit line 30. In this way, a process flow rate around the standard flow rate is restored.

[0052] A method for concentrating a liquid food product according to the present invention is described below. The liquid food product to which reference is made is for example fruit, vegetable and similar juices, purees and creams, in particular tomato juice.

[0053] Such a method is advantageously implemented by a plant for concentrating a liquid food product as described above.

[0054] The method comprises a step of making the product to be treated flow along an entry line 20 towards a concentrator apparatus 10. With regards to the concentrator 10, see what has already been described and specified above. The method comprises a step of treating the product in the concentrator apparatus 10.

[0055] The method comprises a step of making the treated product flow along an exit line 30.

[0056] Originally, the method comprises a step of collecting from the exit line 30 at least a part of treated product and a step of bringing into the entry line 20 the part of collected product. These steps preferably take place through a bypass line 40 that extends between the exit line 30 and the entry line 20.

[0057] Preferably, the bypass line 40 puts in selective fluid communication the exit line 30 with the entry line 20. Preferably, the step of collecting from the exit line 30 and the step of bringing into the entry line 20 take place by enabling communication from the exit line 30 to the entry line 20 through the bypass line 40.

[0058] According to one embodiment, the method comprises a step of collecting from the entry line 20 at least a part of product to be treated and a step of bringing into the exit line 30 the collected part of product to be treated.

[0059] These steps preferably take place through the same bypass line 40, in the opposite direction to what is provided above. This means that the step of collecting from the exit line 30 described above and the step of collecting from the entry line 20 can take place exclusively alternatively.

[0060] Preferably, the step of collecting from the entry line 20 and the step of bringing into the exit line 30 take place by enabling communication from the entry line 20 to the exit line 30 through the bypass line 40.

[0061] The invention achieves important advantages.

[0062] In particular, the possibility of diverting a part of flow rate in the bypass line to bring it to the entry line allows situations to be managed in which the product flow rate at the entry is lower than a standard situation, for which the concentrator has been designed. In this way, the plant and method are versatile, as they can operate not only under nominal flow rate conditions. It is also possible to produce finished products at a higher Brix value. This advantage is further accentuated by the possibility of managing the bypass line also in the opposite direction, i.e. to bring the product from the entry line to the exit line. This allows situations to be managed where the product flow rate at the entry is in excess compared to standard conditions, for which the concentrator was designed. This further possibility accentuates the versatility and adaptability of the plant and method.

[0063] In other words, the proposed plant is standardized. The different operating modes, in fact, do not entail changes to the main heat exchanger, managing the flow rate with the bypass line in either direction, always guaranteeing a “liquid feed rate” suitable for the pipes of the exchanger.

[0064] In addition, the plant proposed in the present invention allows maintaining a feed condition for the pipes (i.e., a fundamental parameter is respected in the concentrators, which is the so-called “liquid feed rate”) without structurally modifying the concentrator. This is allowed by the bypass line and operating modes described.

[0065] In addition, in the “Extra Brix” operating mode (second mode) the residence time of the product in the concentrator is lower in the present invention than in the corresponding ad hoc plant. The sizing must be done through reasoning with the same evaporated heating fluid. In fact, in one case (flow rate lower than a predefined value, first condition) an ad hoc plant requires more steps (stages) smaller than a standard plant, since there is less flow rate. With more steps, the number of down pipes for the product and the number of pumps also increases, which implies a greater volume of product and ultimately, a longer residence time.

[0066] The invention thus conceived is susceptible of numerous modifications and variants, all falling within the scope of the inventive concept that characterises it. Moreover, all the details may be replaced by other technically equivalent elements. All the materials used, as well the dimensions, may in practice be any whatsoever according to needs.

Claims

CLAIMS1. A concentration plant (100) for a liquid food product, such as fruit, vegetable and similar juices, purees and creams, comprising: a concentrator apparatus (10); an entry line (20) of entry to the concentrator apparatus (10) for the food product to be treated; an exit line (30) of exit from the concentrator apparatus (10) for the treated food product, characterised in that it comprises: a bypass line (40) having extent between the exit line (30) and the entry line (20), said bypass line (40) putting in selective fluid communication the exit line (30) with the entry line (20); a control unit (50) configured to, in response to a first signal, enable communication from the exit line (30) to the entry line (20) through the bypass line (40) such that at least a part of the treated food product flows in the entry line (20).

2. The concentration plant (100) according to claim 1 , wherein said control unit (50) is also configured to, in response to a second signal, enable communication from the entry line (20) to the exit line (30) through the bypass line (40) such that at least a part of the food product to be treated flows in the exit line (30).

3. The concentration plant (1 ) according to claim 2, comprising product flow rate transfer means (60), said concentration plant (100) being configurable at least in:- a first standard operating mode, in which the bypass line (40) and the transfer means (60) are inactive and the product flows entirely through the concentrator apparatus (10);- a second operating mode, in which the transfer means (60) make at least a part of the treated food product flow from the exit line (30) to the entry line (20) through the bypass line (40);- a third operating mode, in which the transfer means (60) make at least apart of the food product to be treated flow from the entry line (20) to the exit line (30) through the bypass line (40).

4. The concentration plant (1 ) according to claim 2 or 3, wherein the first signal identifies a first condition in which the product flow rate along the entry line (20) assumes a value lower than a first predefined value; the second signal identifies a second condition in which the product flow rate along the entry line (20) assumes a value higher than a second predefined value, greater than the first.

5. The concentration plant (100) according to any one of the preceding claims, wherein said concentrator apparatus (10) comprises an outer tubular shell (2) inside which there is provided: a heat exchanger (1 ), in which a heating fluid circulates, defined by an upper plate (3) and a lower plate (4) on which the open ends of a bundle of down pipes (5) are fixed in which the product to be treated circulates so that the upper ends of the down pipes (5) open into an entry zone (6) of the heat exchanger (1) in which the product is distributed, and the lower ends of the down pipes (5) open into a bottom zone which is a separation chamber (7) of the heat exchanger (1 ); said down pipes (5) being divided into a plurality of sectors (8) in which the product circulates in succession; at least one pipe (9) for the ascent of the product for each sector (7).

6. A method for concentrating a liquid food product, such as fruit, vegetable and similar juices, purees and creams, comprising the steps of: letting the food product to be treated flow along an entry line (20) towards a concentrator apparatus (10); treating the food product in the concentrator apparatus (10); letting the treated food product flow along an exit line (30); characterized in that it comprises a step of collecting from the exit line (30) at least one part of treated food product and a step of bringing into the entry line (20) said at least one part of collected food product.

7. The concentration method according to claim 6, wherein the step ofcollecting from the exit line (30) and the step of bringing into the entry line (20) take place by enabling communication from the exit line (30) to the entry line (20) through a bypass line (40).

8. The concentration method according to claim 6 or 7, comprising a step of collecting from the entry line (20) at least one part of food product to be treated and a step of bringing into the exit line (30) said at least one part of collected food product.

9. The concentration method according to claim 8, wherein the step of collecting from the entry line (20) and the step of bringing into the exit line (30) take place by enabling communication from the entry line (20) to the exit line (30) through a bypass line (40).

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