WO2025088417A1

WO2025088417A1 - Concentration plant for food industry with steam saving and concentration method thereof

Info

Publication number: WO2025088417A1
Application number: PCT/IB2024/059905
Authority: WO
Inventors: Annalisa GHILLANI; Mattia Bonatti; Paolo Frascari
Original assignee: Fenco Food Machinery Srl
Current assignee: Fenco Food Machinery Srl
Priority date: 2023-10-23
Filing date: 2024-10-10
Publication date: 2025-05-01
Anticipated expiration: 2026-04-23

Abstract

A concentration plant (10) for the chemical and food industry comprises at least a pre- concentration evaporator (12) for a liquid product to be concentrated with at least a first recirculation circuit (20), at least a first heat exchanger (14) and at least a separation chamber (16); at least an intermediate evaporator (22) with a second recirculation circuit (30), said intermediate evaporator (22) being provided with at least a second heat exchanger (24) and at least a second separation chamber (26); at least a finishing evaporator (32) connected with a third recirculation circuit (40), at least a third heat exchanger (34) and at least a third separation chamber (36). Said first, second and third recirculation circuits (20, 30, 40), are placed in fluid connection in series with each other by means of at least a transfer section (55), and said concentration plant (10) comprises a compressor unit (50) connected on suction side with said separation chambers (16, 26) and on delivery side with said first heat exchanger (14) by means of a steam recompression circuit (52). Said concentration plant also comprises at least a second compressor unit (60) connected on the suction side by tapping with said recompression circuit (52) and on the delivery side with at least one between the second heat exchanger (24) of said intermediate evaporator (22) and the third heat exchanger (34) of said finishing evaporator (32) by means of a second recompression circuit (62), in such a way as to realize a second or n-th recompression at higher pressure. The invention also relates to method of concentration for a liquid product for the food or chemical industrial sector.

Description

Description of the industrial invention entitled:

"CONCENTRATION PLANT FOR FOOD INDUSTRY WITH STEAM SAVING AND CONCENTRATION METHOD THEREOF";

In the name of: FENCO FOOD MACHINERY S.r.l.

FIELD OF TECHNOLOGY

The present invention relates to a concentration plant for the food industry with steam saving and concentration method thereof.

More particularly, the present invention relates to a falling film, forced circulation concentration and evaporation plant for products and juices in the chemical and food industry, with steam saving and reduced energy consumption, and to a method thereof implemented by any concentration plant.

STATE OF THE PRIOR ART

In the food industry, and more generally in the industrial chemical field, evaporator and concentrator plants or groups are well known and used for the industrial production of food products such as tomato juice, fruit juices, milk, whey or even wastewater to be disposed of, configured to concentrate the product by removing excess water.

One of the most relevant processes for these types of evaporator/ concentrator plants is the process for producing and concentrating tomato juice.

In this process, the fresh fruit is preliminarily washed and crushed into a heterogeneous fluid mass, and the resulting product is subjected to an enzymatic deactivation treatment aimed at blocking the development of pectolytic enzymes and heated to specified temperatures over a specified time.

Two types of enzyme deactivation processes, typically known as hot Break and Cold Break, can be distinguished, depending on the temperatures and the time required for the product to reach and remain at the set temperatures.

In the process defined as Hot Break, the product is brought to temperatures in the range of 95 °C in such a way as to inactivate the enzymes present in the product, making the juice more viscous. In the process defined as Cold Break, enzyme deactivation is achieved at lower temperatures than the Hot Break process, typically between 65 and 75 °C, and with a less viscous juice.

The resulting product is then processed through a pulper or finisher in which the tomato juice is separated from the skins and seeds, which are discarded, and sent to the evaporation plant to obtain a product at the desired concentration.

The concentration, e.g. of tomato juice, can be determined using various methods, including measuring the refractive index, specific weight and water solubility of the concentrated product.

In the chemical and food industry, a unit of measurement called Brix or degrees Brix [°Bx] is commonly used to determine the concentration of a product containing sugars. The value expressed in °Bx indicates the sucrose amount dissolved in a mass of liquid solution, but it is also used during the concentration process of tomato juice, or other products, to determine the extraction rate of the product during concentration, the higher the degree expressed in °Bx, the higher the concentration of the product.

Commercially, tomato concentrate is considered as such if it has a concentration of around 28/30 °Bx, also referred to as double concentrate, or above 36 °Bx, also referred to as triple concentrate.

The product obtained after the first process, in the case for example of tomato juice, which finishes the process in the tomato pulper/ finisher has a concentration varying from 4 to 5 °Bx, is sent, for the next stages, to the relevant concentration plant generally composed of several concentration stages operating with a vapor recovery scheme generated by the evaporation of the product itself. In multiple-effect plants, where there are several stages/ effects connected in series, an attempt is made to increase the energy efficiency value. To achieve this, the steam produced is used as a heating fluid for the next evaporation operation.

Therefore, the steam produced in a first effect can be used as the heating fluid for a second effect and so on, only if a pressure difference is established between the different effects, i.e., by moving from one effect to the next there is a progressive decrease in pressure and thus also in the boiling temperature of the solution, or rather in the steam produced. Economic considerations related to plant cost limit the maximum number of evaporators in a multipleeffect plant to five to six effects. It should be kept into consideration that during the concentration phases of a solution, the presence of the solute causes an increase in the boiling temperature, so called boiling-point elevation, or rather the solution boils at a higher temperature than the pure solvent at the same external pressure. This phenomenon is a typical colligative property, i.e., it depends on the number of particles of the solute, so its possible dissociation must also be considered. The difference between the boiling point of the solution and the boiling point of the pure solvent is called IPE (Boiling Point Elevation). The IPE is a consequence of the decrease in the equilibrium vapor pressure of the solution compared to the pure solvent at the same temperature: in fact, the solvent molecules interact with the solute and thus pass more difficultly into the vapor phase.

In MVR (Mechanical Vapor Recompression) types of evaporators, the energy efficiency value is increased through the use of centrifugal fans, usually powered by electricity or equivalent machines, which take advantage of the recompression of the vapor generated by the evaporation of the product by raising its temperature and using it as a heating fluid in the same evaporator (effect).

In the current state of the art in MVR evaporators after an first pre-concentration step with vapor recompression, again with exemplary reference to tomato juice, a product is obtained at about 12 °Bx, which to be brought to a concentration of about 30 °Bx requires at least a further concentration step by means of a conventional, typically multi-stage/ multi-effect evaporator with a forced circulation heat exchanger, connected to a source of steam typically generated by a boiler by means of hydrocarbons combustion.

An example of these well-known MVR concentration plants with vapor recovery is described in the European Patent Application EP 4 190 160 (Al).

Elowever, said well-known concentration and evaporation plants and processes for the chemical and food industries have drawbacks and operational limitations.

A typical limitation of these well-known evaporation plants and processes is due to the fact that they are highly energy-consuming and have to draw energy in different forms and from multiple sources, such as electricity and steam generally produced by the combustion of hydrocarbons.

A further typical limitation of these well-known evaporation plants and processes with mechanical vapor recompression, in the typical case of tomato concentrate, is due to the fact that due to the boiling-point elevation during concentration it is possible to obtain a 12 /14 Bx concentrated juice at the outlet, and a further concentration step is necessary to reach the 30 °Bx concentrate via multi-stage/ effect evaporation plant using steam as an energy source. Another typical limitation of these well-known evaporation plants and processes is due to the consumption of clean water and the cost of purifying and disposing of the condensates collected at the outlet.

The subject matter of the present invention is to overcome and obviate, at least in part, the above-mentioned drawbacks and operational limitations.

More particularly, the subject matter of the present invention is to provide a concentration plant for the chemical and food industry with high thermal efficiency with reduced energy consumption required in the process of evaporation and concentration of the final product to the desired concentration.

Further subject matter of the present invention is to provide a concentration plant for the chemical and food industry capable of concentrating the product up to a concentration of 30 to 36 °Bx only by using the consumption of electrical energy and without or with limited use of steam obtained by means of other energy sources derived from the combustion of gas or other fossil fuels.

Not the least subject matter of the present invention is to provide to the user a concentration plant for the chemical and food industry that can allow the recovering and reusing condensation water in order to limiting factory’s water consumption and achieving energy recovery.

Still another subject matter of the present invention is to provide a concentration plant for the chemical and food industry that can guarantee an elevated level of durability and reliability over time, and which can also be easily and economically manufactured.

These and other object are achieved by the concentration plant for the chemical and food industry and the related concentration method subject matter of the present invention, in accordance with the independent claims.

The structural and functional features of the concentration plant for the chemical and food industry and the related concentration method which is the subject of the present invention can be better understood from the detailed description below, in which reference is made to the attached drawings which represent some preferred and non-limiting embodiments, in which:

BRIEF DESCRIPTION OF THE FIGURES

Figure 1 is a schematic and exemplary representation of a general embodiment of the evaporation plant subject matter of the present invention with multiple stages of evaporators and with the use of a double stage mechanical compressor or "booster."

Figure 2 is a schematic and exemplary representation of a further embodiment of the evaporation plant subject matter of the present invention with multiple stages of evaporators, with the use of a double stage of mechanical compression or "booster" and with an additional steam source;

Figure 3 is a schematic and exemplary representation of an embodiment of the evaporation plant subject matter of the present invention with multiple stages of evaporators and with the use of a double stage mechanical compressor or "booster" and a refining unit or decanter to remove the pulp fraction from the fibrous material of the inlet product;

Figure 4 is a schematic and exemplary representation of an embodiment of the evaporation plant subject matter of the present invention with multiple stages of evaporators and with the use of a double stage of mechanical compression or "booster" with recovery and purification by osmosis or ultra-filtration of the condensate outlet;

DETAILED DESCRIPTION OF THE INVENTION

With initial reference to all figures and particularly Figure 1, the concentration 10 plant for the chemical and food industry subject matter of the present invention is described below in a simplified embodiment.

The concentration plant 10 comprises: at least a pre-concentration evaporator 12, for a juice or liquid product to be concentrated, with at least a first recirculation circuit 20 comprising a first recirculation pump 18 for the product to be concentrated, said pre-concentration evaporator 12 being provided with at least a first heat exchanger 14, preferably with falling film and mixed circulation, and at least a separation chamber 16; at least an intermediate evaporator 22, suitable for being fed by the product from said at least a pre-concentration evaporator 12, provided with at least a second heat exchanger 24 with at least a second forced recirculation circuit 30 comprising a second recirculation pump 28 for the product to be concentrated, said intermediate evaporator 22 being provided with at least a second heat exchanger 24 preferably with forced circulation and a second separation chamber 26; at least a finishing evaporator 32, capable of being fed by product from said intermediate evaporator 22, with at least a third forced recirculation circuit 40 including a third recirculation pump 38 for the product to be concentrated, said finishing evaporator 32 being provided with at least a third heat exchanger 34 preferably with forced circulation and at least a third separation chamber 36.

Said first, second, and third recirculation circuits 20, 30, 40 are arranged in fluid connection in series with each other by means of at least a transfer circuit or transfer section 55 generally including at least a transfer pump 56 for the product to be concentrated.

The concentration plant 10 also comprises a compressor unit 50 of said at least a preconcentration evaporator 12 and of said at least an intermediate evaporator 22, generally connected on the suction side with said at least a separation chamber 16 and said at least a second suction chamber 26 and connected on the delivery side with said first heat exchanger 14 of said at least a pre-concentration evaporator 12 by means of a vapor recompression circuit 52.

The concentration plant 10 subject matter of the present invention comprises the innovative features of at least a second compressor unit 60 also called "booster", advantageously connected by tapping on suction side with said recompression circuit 52 and on delivery side with at least a between the second heat exchanger 24 of said intermediate evaporator 22 and the third heat exchanger 34 of said finishing evaporator 32, by means of a second vapor recompression circuit 62, so that a second or n-th recompression of the evaporation steam can be achieved at a higher pressure and thus a higher condensation temperature. In a variant embodiment, not shown, said concentration plant 10 can advantageously comprise a plurality n-th of said at least a pre-concentration evaporator 12 with a plurality of said first forced recirculation circuit 20 provided with a first heat exchanger 14 and a separation chamber 16 and comprising at least a first recirculation pump 18 for the food product to be concentrated, said plurality of at least a pre-concentration evaporator 12 being arranged in series in a configuration with a traditional multi-stage scheme in which said compressor unit 50 is connected on suction side with the separation chamber 26 of each n- th pre-concentration evaporator 22 and on delivery side with each n-th first heat exchanger 14 of each n-th pre-concentration evaporator 12 by means of an n-th vapor recompression circuit 52.

In further variant forms, not shown, the concentration plant 10 can also provide for and comprise an n-th plurality of said intermediate evaporator 22 with an n-th plurality of said second forced recirculation circuit 30 connected in series and comprise an n-th plurality of said finishing evaporator 32 placed in fluid connection with an n-th plurality of said third forced recirculation circuit 40 connected in series.

Said compressor unit 50 and said second compressor unit 60 preferably comprise a centrifugal fan such as a turbo-compressor or a radial turbo pump driven by an electric motor, but it can also comprise other types of volumetric compressors, for example rotary lobe compressors, screw compressors or equivalent.

The fan and the driving electric motor of said second compressor unit 60, advantageously connected on delivery side to the recompression circuit 52 of the compressor unit 50, are preferably smaller in size and capacity than those of the main compressor unit 50, because there is less steam to be compressed and sent to the next stages at higher temperature and pressure, through the second vapor recompression circuit 62, wherein the heat exchange takes place with a much more concentrated product than that circulating in one or more of the pre-concentration evaporators 22 and where there is less water to be extracted.

With reference always to all Figures, the evaporation system also generally comprises a condensate outlet circuit 90 arranged at the outlet of the heat exchangers of the different concentration stages.

With particular reference to Figure 2, in an alternative embodiment, said second compressor unit 60 of said concentration plant 10 subject matter of the present invention, can be connected on suction side by tapping with said recompression circuit 52 and on delivery side with said second heat exchanger 24 of said intermediate evaporator 22, and where said third heat exchanger 34 of said finishing evaporator 32 can be connected with an external steam source by means of a feed circuit 72 comprising a traditional Venturi effect ejector 70 of recirculation, to bring the final product to a desired concentration.

With reference again to the figures, the concentration plant 10 subject matter of the present invention can comprise a inlet product tank 100 for the inlet product storage connected to an inlet circuit section 11 to the first evaporation stage and can comprise a concentrated product tank 102 for the final product storage connected to an outlet circuit section 11' to the last evaporation stage.

With particular reference now to Figure 3, the concentration plant 10 subject matter of the present invention can advantageously also comprise a refining unit 80 or decanter in which the inlet product to the first stage of the concentration plant 10, typically tomato juice, is pumped after being passed through a refiner or pulper not shown and filtered through a sieve with holes <0.4 mm in order to separate all the pulp and the fibrous part from the tomato juice so as to obtain a juice, with lower viscosity, to be sent to the pre-concentration plant in order to increase its flowability even as the concentration increases, so as to increase the concentration limits achievable at the state of the art in the falling film section.

Said refining unit 80 is arranged in fluid connection by means of a bypass circuit 82 with one or more transfer sections 55 to reintroduce the fibrous matter portion of the product already partially concentrated in various stages.

With particular reference also to Figure 4, the concentration 10 plant subject matter of the present invention can also advantageously comprise a condensate treatment device 92 using reverse osmosis or ultra-filtration, capable of removing biological residues present in the produced evaporation steam, said condensate treatment device being connected with the condensate outlet circuit 90 and configured for reintroducing clean water at about 78 °C back into the plant or in a factory water network in order to send it to various uses and exploit its heat as additional energy savings.

It is also subject matter of the present invention a low energy consumption concentration method for a product to be concentrated such as tomato juice, fruit juices and purees, milk serums or other products of the chemical industry etc., as previously described.

The concentration method comprises the steps of: providing a food or chemical-industrial product to be concentrated in a concentration plant 10; performing at least a pre-concentration by recirculating or sending the food product in a single pass in at least a heat exchanger 14 and at least a separation chamber 16 of a pre-concentration evaporator 12 in a first recirculation circuit 20; transferring with a transfer section 55 and performing an intermediate concentration by recirculating the food product in at least a second heat exchanger 24 and in at least a second separation chamber 26 of an intermediate evaporator 22 in a second recirculation circuit 30; transferring with a transfer section 55 and performing a finishing concentration by recirculating the food product in at least a third heat exchanger 34 and in at least a third separation chamber 36 of a finishing evaporator 32 in a third recirculation circuit 30; performing a first recompression of the evaporation steam with a compressor unit 50 in suction from the separation chambers 16, 26 until the temperature e is increased: sending said compressed steam at higher pressure and temperature through a recompression circuit into said first heat exchanger 14 of said pre-concentration evaporator 12 and: performing a first heat exchange of vapor recovery with the food product to be concentrated; tapping and suction of steam from said recompression circuit 52 and; performing a second recompression of the evaporation steam with a second compressor unit 60 until the steam temperature is further increased and: sending said compressed steam at a higher pressure and temperature than said first recompression through a second recompression circuit 62 into the heat exchanger of an evaporator next to said pre-concentration evaporator 12 and; performing a further second heat exchange condensation of vapor recovery with the food product.

From the description of the concentration plant 10 for the chemical and food industry and the related concentration method for a food product to be concentrated subject of the present invention, the operation described below is evident.

With initial reference to Figure 1, the concentration plant 10 of the present invention works by recirculating a fluid product to be concentrated, such as tomato juice, through multiple evaporation stages.

The product to be concentrated is passed, in the first pre-concentration stage, into the preconcentration evaporator 12, or a plurality of them, connected in a multiple -stage scheme, of the first recirculation circuit 20 in which the product to be concentrated is recirculated by means of a first recirculation pump 18.

The product to be concentrated, after being recirculated several times in a stage, or alternatively sent to single pass and thus concentrated, is passed to a next stage in successive evaporators with a higher concentration, for example in the second heat exchanger 24 and the second separation chamber 26 of the intermediate evaporator 22 and connected with the second forced recirculation circuit 30, because of the higher viscosity of the product, and recirculated with a second product recirculation pump 28 and then again in a third stage of said finishing evaporator 32 through the circuits or transfer sections 55.

In the plant thus started, the compressor unit 50 connected by suction with the separation chambers 16 and 26 compresses evaporation steam having the same temperature as the product to be concentrated in the separation chambers, net of the boiling-point rise, the steam is recompressed at a higher pressure so as to raise the temperature and recondense in the first exchanger in the first pre-concentration evaporator 12.

The concentration plant 10 of the present invention comprises the novel features of having a second compressor 60 or "booster," which draws in steam already recompressed once from the recompression circuit 52 and compresses it a second time in a second recompression stage further raising the pressure and temperature of the steam which, sent to a next heat exchanger 24 of an evaporator of another stage makes it possible to bring the product to be concentrated to a final concentration of more than 28 °Bx, in the example case of tomato juice, without the use of an additional steam source from a boiler, allowing energy savings and reduction of harmful emissions to the environment and also allowing the plant to operates for the whole concentration process using only electrical energy.

With particular reference to Figure 2, in an alternative embodiment, the second compressor unit 60 connected on suction side by tapping with the recompression circuit 52 advantageously sends steam at higher pressure and temperature to the heat exchanger 24 of the intermediate evaporator 22 only, while the third heat exchanger 34 of the finishing evaporator 32 receives energy, even though in a more limited manner than in conventional concentration plants, from an external source of steam coming from the Venturi-effect ejector 70 of the feed circuit 72, in order to bring the final product to a pre-established concentration. However, this stage of energy withdrawal through an external steam source is reduced in plant size and consumption and is mainly used in the concentration plant 10 of the present invention to having a control and regulation option for the concentration process.

With particular reference now to Figure 3, the concentration plant 10 can recover energy by means of the refining unit 80, in which the product entering in concentration plant 10 has been preliminarily passed through a decanter or pulper/ refiner and filtered with a sieve, with holes typically less than 0.4 mm in size, which separates much of the pulp and its fibrous portion from the tomato juice, leaving the juice with less fiber and therefore more suitable to be concentrated in the pre-concentrator. In this way, the first concentration step, called pre-concentration, can be pushed beyond the current concentration limit of 12 °Bx thus using the first vapor recompression circuit that has less energy consumption. The fibrous portion stored in the settling unit is then returned to the more concentrated product of the later stages.

With particular reference also to Figure 4, the concentration plant 10 subject matter of the present invention can further recover energy by means of the condensate treatment device 92 which can operate on the principle of reverse osmosis or by ultra-filtration to break down the remaining biological residues in the vapor derived from the evaporation and concentration of the food product. The condensates thus purified and collected in the relevant circuit at a temperature of about 78 °C, equal to that of the product in the separation chambers, net of the boiling-point elevation, can be advantageously reused for the purpose of being sent to boiler tanks to produce steam and for technical uses thus advantageously limiting the withdrawal of fresh water at a temperature in the range of 20 °C and the energy for its heating from 20 °C to 78 °C.

As can be seen from the foregoing, the advantages that the concentration plant 10 for the chemical and food industry and the related concentration method for a product to be concentrated that is the subject of the present invention achieve are obvious.

With reference to all the Figures, the concentration plant 10 capable of implementing the related concentration method subject matter of the present invention, for a food or chemical industrial fluid product, are particularly advantageous because they guarantee a significant and reduced energy consumption, compared to a traditional concentration plant and method, due to an additional innovative and efficient energy recovery achieved by double or n-th recompression of the evaporation steam at higher temperatures capable of recondensing and exchanging heat with the product even as a result of the boiling-point rising of the more concentrated product.

Further advantage of the concentration 10 plant subject matter of the present invention is due to only one source of energy and that is electrical energy is available for the operation of the 50, 60 compressor units, which results in greater simplicity and ease of maintenance of the plant.

A further advantage of the concentration plant 10 for the chemical and food industry and the related concentration method for a product to be concentrated is that it provides the user with a plantwith low power consumption and environmental emissions, capable of operating on electric power alone without the use of energy produced by the combustion of hydrocarbons, or at least with use in minimal amounts and limited to controls and adjustments of the concentration process. Further advantage again of the concentration plant 10 for the chemical and food industry and the related concentration method for a product to be concentrated is to provide the user with a plant that ensures limited consumption of fresh water through efficient recovery and reintroduction into the plants of condensates and the residual heat they contain.

Although the invention has been described above with particular reference to several embodiments, given for exemplary and non-limiting purposes, numerous modifications and variations will appear obvious to a person skilled in the art in the light of the above description. The present invention, therefore, is intended to embrace all modifications and variations falling within the scope of protection of the following claims.

Claims

C L A I M S

1. A concentration plant (10) for chemical and food industry comprising: at least a pre-concentration evaporator (12) for a liquid product to be concentrated with at least a first recirculation circuit (20), said at least a pre-concentration evaporator (12) being provided with at least a first heat exchanger (14) and at least a separation chamber (16); at least an intermediate evaporator (22) with a second recirculation circuit (30), said intermediate evaporator (22) being provided with at least a second heat exchanger (24) and at least a second separation chamber (26); at least a finishing evaporator (32) connected with a third recirculation circuit (40), said finishing evaporator (32) being provided with at least a third heat exchanger (34) and at least a third separation chamber (36); wherein said first, second and third recirculation circuits (20, 30, 40), are placed in fluid connection in series with each other by means of at least a transfer section (55) for the product to be concentrated; said evaporation plant (10) also comprises a compressor unit (50) connected on suction side with said separation chambers (16, 26) and on delivery side with said first heat exchanger (14) of said at least a pre-concentration evaporator (12) by means of a steam recompression circuit (52); characterized in that it comprising at least a second compressor unit (60) connected on the suction side by tapping with said recompression circuit (52) and on the delivery side with at least one between the second heat exchanger (24) of said intermediate evaporator (22) and the third heat exchanger (34) of said finishing evaporator (32) by means of a second recompression circuit (62), so as to realize a second or n-th recompression of steam at higher pressure.

2. The concentration plant (10) according to claim 1, comprising a plurality n-th of said at least a pre-concentration evaporator (12) with a plurality of said first recirculation circuit (20) wherein said plurality n-th of said pre-concentration evaporator (12) is arranged in series in a configuration with an o multiple effect scheme in which said compressor unit (50) is connected on suction side with the separation chamber (26) of each n-nth preconcentration evaporator (22) and on the delivery side with each n-th first heat exchanger (14) of each n-th pre-concentration evaporator (12) by means of n-th steam recompression circuit (52).

3. The concentration plant (10) according to claim 1, wherein said second compressor unit (60) is connected on suction side by tapping with said recompression circuit (52) and on delivery side with said second heat exchanger (24) of said at least an intermediate evaporator (22), and wherein said third heat exchanger (34) of said finishing evaporator (32) is connected with an external steam source by means of feed circuit (72) comprising an ejector (70) with Venturi effect to bring the final product to a set concentration.

4. The concentration plant (10) according to claim 1, comprising a refining unit (80), arranged in fluid connection by means of a bypass circuit (82) with one or more transfer sections (55).

5. The concentration plant (10) according to claim 1, comprising a condensate treatment device (92) connected with a condensate outlet circuit (90) designed to remove biological residues present in the condensation vapor and to feed clean water back to the condensation plant (10) or other related facilities.

6. The concentration plant (10) according to claim 5, where said condensate treatment device (92) is a reverse osmosis or ultra-filtration device.

7. A concentration method for a food product to be concentrated comprising the steps of: providing a food product to be concentrated in a condensing plant (10); performing at least a pre-concentration by recirculating the food product in a first heat exchanger (14) and a separation chamber (16) of a pre-concentration evaporator (12) in a first recirculation circuit (20); transferring with a transfer section (55) and make an intermediate concentration by recirculating the food product in a second heat exchanger (24) and a second separation chamber (26) of an intermediate evaporator (22) in a second recirculation circuit (30); transferring with a transfer section (55) and perform a finishing concentration by recirculating the food product in a third heat exchanger (34) and a third separation chamber (36) of a finishing evaporator (32) in a third recirculation circuit (30); performing a first recompression of the evaporation steam with a compressor unit (50) sucked in from the separation chambers (16, 26) until the temperature e is increased: sending through a recompression circuit said compressed steam at higher pressure and temperature into said first heat exchanger (14) of said pre-concentration evaporator (12) and: performing a first vapor recovery heat exchange with the food product to be concentrated; tapping and suction of steam from said recompression circuit (52) and; performing a second recompression of the evaporation steam with a second compressor unit (60) until its temperature is further increased e: sending through a second recompression circuit (62) said compressed steam at a higher pressure and temperature than said first recompression into the heat exchanger of an evaporator subsequent to said pre-concentration evaporator (12) and; performing an additional second condensation vapor recovery heat exchange with the food product.