Method And Assembly For Aseptically Heating A Liquid Product In A Heat Exchanger Unit Of The Heater Zone Of A UHT System

Abstract

A method for aseptic heating of a liquid product in a heat exchanger unit in a UHT system is described. The heat exchanger unit is a tubular heat exchanger, in which an indirect heat exchange on a wall takes place between the liquid product and a heating medium by a single heating medium flow with a heating medium inlet temperature flowing in a heat-releasing heating medium chamber between a heating medium inlet and outlet of the heat exchanger unit running countercurrent to a flowing single product flow guided in a heat-absorbing product chamber between a product input and output of the heat exchanger unit. A total heat exchanger path is formed between the product input and output, in which the product flow is heated from a product input temperature to a product output temperature. At least the product output temperature and the heating medium inlet temperature are monitored and regulated.

Claims

1. A method for aseptic heating of a liquid product (P) in a heat exchanger unit of a heater zone of an arrangement in a ultra-high temperature (UHT) system in which an indirect heat exchange on a wall takes place in the heat exchanger unit between the liquid product and a heating medium by a flowing heating medium flow with a heating medium inlet temperature in a heat-releasing heating medium chamber being guided countercurrent to a product flow ) in a heat-absorbing product chamber, in which the product flow is heated from a product input temperature to a product output temperature and in which at least the product output temperature and the heating medium inlet temperature are monitored and regulated, the method comprising: (A1) setting an unknown product-specific temperature curve between the product input temperature and the product output temperature with the aid of a supply of a required heating medium flow with a required heating medium inlet temperature at a heating medium inlet into the heating medium chamber and measuring discrete product temperatures at specified measurement points in the product flow; (B1) specifying the product input temperature at a product input into the product chamber and the product output temperature at a product output from it and providing the heating medium inlet temperature and heating medium flow; (C) measuring a product-specific temperature curve between the product output and the product input at the specified measurement points; (D1) comparing the temperature curves for method steps (A1) and (C) and calculating the respective temperature deviations at the specified measurement points; (E) specifying a permitted temperature deviation; and (F) changing of the heating medium inlet temperature to a target heating medium inlet temperature when the permitted temperature deviation is exceeded by the calculated temperature deviation.

2. A method for aseptic heating of a liquid product in a heat exchanger unit of a heater zone of an arrangement in a ultra-high temperature (UHT) system in which an indirect heat exchange on a wall takes place in the heat exchanger unit between the liquid product and a heating medium by a flowing heating medium flow with a heating medium inlet temperature in a heat-releasing heating medium chamber being guided countercurrent to a product flow in a heat-absorbing product chamber, in which the product flow is heated from a product input temperature to a product output temperature and in which at least the product output temperature and the heating medium inlet temperature are monitored and regulated, the method comprising: (A2) setting a known product-specific target temperature curve with the aid of measuring discrete product temperatures at specified measurement points in the product flow and with the aid of a supply of a required heating medium flow with a required heating medium inlet temperature at a heating medium inlet into the heating medium chamber; (B2) specifying the product-specific target temperature curve, which includes the product input temperature at a product input into the product chamber and the product output temperature at a product output out of it, and providing a stored supply of the heating medium flow with a heating medium inlet temperature; (C) measuring a product-specific temperature curve between the product output and the product input at the specified measurement points; (D2) comparing the temperature curves for method steps (A2) and (C) and calculating temperature deviations at the specified measurement points; (E) specifying a permitted temperature deviation; and (F) changing the heating medium inlet temperature to a target heating medium inlet temperature when the permitted temperature deviation is exceeded by the calculated temperature deviation.

3. The method according to claim 1, further comprising: (G) determining a temperature/time gradient from a change of the heating medium inlet temperature in a specified time span; (H) specifying a reference gradient for a permitted temperature increase of the heating medium inlet temperature in the time span; (I) comparing the results of method step (G) with the specification according to method step (H); and (J) changing the heating medium flow to a target heating medium flow when the reference gradient is exceeded by the temperature/time gradient determined.

4. The method according to claim 1, wherein the change of the heating medium inlet temperature to the target heating medium inlet temperature occurs in each case either in temperature steps or by a continuous temperature change.

5. The method according to claim 1, wherein the change of the heating medium flow to the target heating medium flow occurs in each case either by a stepwise or by a continuous increase.

6. The method according to claim 1, further comprising: measuring a product inlet pressure at a product input and a product outlet pressure at a product output.

7. An arrangement for carrying out the method according to claim 1, with the heat exchanger unit which, seen in the direction of flow of a liquid product to be heated indirectly, is situated between an upstream process unit and a downstream process unit, with the heat exchanger unit, which has a flow-through heat-absorbing product chamber and a flow-through heat-releasing heating medium chamber, with at least one measuring apparatus for product flow, one measuring apparatus for product input temperature, one measuring apparatus for product output temperature, one measuring apparatus for heating medium flow and one measuring apparatus for heating medium inlet temperature, and with a control and feedback unit that controls an output for target heating medium inlet temperature and an output for target heating medium flow, provided on the control and feedback unit, dependent on at least the measuring apparatuses, wherein, in the product chamber of the heat exchanger unit, upstream of the product output and adjacent thereto with defined spacing, at least one temperature measurement point is provided, which is connected to the control and feedback unit via a measuring apparatus for discrete product temperature assigned in each case for measuring discrete product temperatures.

8. The arrangement according to claim 7, wherein, with more than one temperature measurement point, these points are arranged contrary to the direction of flow of the liquid product in series with respect to one another and with defined spacing from one another.

9. The arrangement according to claim 7, wherein the at least one temperature measurement point is arranged in the last third of the flow-through product chamber.

10. A heat exchanger unit for the arrangement according to claim 7, wherein the heat exchanger unit is subdivided into multiple sections connected to one another in series, in that adjacent sections are connected to one another in each case via a first connecting element through which liquid product flows on a product side and via a second connecting element on a heating medium side and in that the respective temperature measurement point is provided in the first connecting element.

11. A heat exchanger unit according to claim 10, wherein the heat exchanger unit is formed as a tubular heat exchanger, that an individual section of the multiple sections of the tubular heat exchanger is formed on the product side in each case as a monotube through which liquid product flows or as a tube bundle with a number of parallel interior tubes through which liquid product flows and in that the first connecting element is formed in each case as a connecting bend or as a connection fitting.

12. The arrangement according to claim 8, wherein the at least one temperature measurement point is arranged in the last third of the flow-through product chamber.

13. A method according to claim 2, further comprising: (G) determining a temperature/time gradient from a change of the heating medium inlet temperature in a specified time span; (H) specifying a reference gradient for a permitted temperature increase of the heating medium inlet temperature in the time span; (I) comparing the results of method step (G) with the specification according to method step (H); and (J) changing the heating medium flow to a target heating medium flow when the reference gradient is exceeded by the temperature/time gradient determined.

14. The method according to claim 2, wherein the change of the heating medium inlet temperature to the target heating medium inlet temperature occurs in each case either in temperature steps or by a continuous temperature change.

15. The method according to claim 2, wherein the change of the heating medium flow to the target heating medium flow occurs in each case either by a stepwise or by a continuous increase.

16. The method according to claim 2, further comprising: measuring a product inlet pressure at a product input and a product outlet pressure at a product output.

17. The method according to claim 1, wherein the heat exchanger unit is formed as a tubular heat exchanger, and is formed on the product side as a monotube through which liquid product flows or as a tube bundle with a number of parallel interior tubes through which liquid product flows.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0076] A more detailed representation of the invention is found in the following description and the drawing figures provided as well as in the claims. While the invention is implemented in the most varied embodiments of a first and a second method of the generic type, with the most varied embodiments of an arrangement for carrying out the method and the most varied embodiments of a heat exchanger unit for such an arrangement, the two methods, a preferred embodiment of an arrangement according to the invention which accommodates an heat exchanger unit according to the invention, and two advantageous embodiments of the heat exchanger unit are described below based on the drawing.

[0077] FIG. 1 is a schematic representation of a section from a prior art UHT system for aseptic heating of a liquid product and a heat exchanger unit of the heater or pasteurization zone.

[0078] FIG. 2 a qualitative representation of the temperature curves of the liquid product to be heated and of the heat-releasing heating medium, which show the temperatures on the Y-axis and a variable heat exchanger path in a schematically shown prior art heat exchanger unit on the X-axis.

[0079] FIG. 3 is a flow diagram of a first and a second method for aseptic heating according to the teachings herein.

[0080] FIG. 4 is a schematic representation of an arrangement with a heat exchanger unit for carrying out the two methods according to FIG. 3.

[0081] FIG. 5 is a diagram for representing the temperature curves in the heat exchanger unit according to FIG. 4.

[0082] FIG. 6A is a front view of a preferred embodiment of the heat exchanger unit according to FIG. 4.

[0083] FIG. 6B is a schematic and enlarged representation of a first embodiment of the heat exchanger unit according to FIG. 6A based on a detail in reference to the formation of the heat-absorbing product chamber labeled there with Z.

[0084] FIG. 6C is a schematic and enlarged representation of a second embodiment of the heat exchanger unit according to FIG. 6A based on a detail in reference to the formation of the heat-absorbing product chamber labeled there with Z.

DETAILED DESCRIPTION

[0085] An arrangement 20 according to FIG. 4, which represents a section from a UHT system, is largely identical in its basic construction with the previously described arrangement 10 according to FIG. 1. Therefore, a renewed description in this regard is omitted. The difference between the arrangement 10 and the arrangement 20 consists of the fact that in the product chamber 22.1 of the heat exchanger unit 22 at least one temperature measurement point 22.3 is provided upstream of the product output A.sub.P and adjacent thereto. The at least one temperature measurement point 22.3 in the embodiment has a spacing from the product input E.sub.P, which is designated with a discrete heat exchanger path I.sub.x1, and thus has a defined spacing LI.sub.x1 from the product output A.sub.P according to the measure of an entire heat exchanger path L. The temperature measurement points 22.3 are situated in series with respect to one another and spaced from one another with a defined measurement point interval l, contrary to the direction of flow of the liquid product P. Each of these measurement points 22.3 is connected to the control and feedback unit 24 via an associated measuring apparatus for discrete product temperature 25 in each case for measuring discrete product temperatures T.sub.P or T.sub.P1 to T.sub.Pn. Furthermore, it is provided that a measuring apparatus for product inlet pressure 27.1 measures a product inlet pressure p.sub.E and a measuring apparatus for product outlet pressure 27.2 measures a product outlet pressure p.sub.A. An optional measuring apparatus for heating medium outlet temperature 30.2 measures the heating medium outlet temperature T.sub.MA.

[0086] The features and reference values in FIG. 2, which were defined and explained above, are also found identically or in a modified form only with regard to designation to some extent in FIG. 3 and predominantly in FIGS. 5 and 6A-6C. In this regard as well, a renewed definition and explanation is omitted below. With reference to the subject matter of the invention, only the additional or different features and reference values will be introduced and explained.

[0087] The first and second methods according to the invention are illustrated in FIG. 3, in each case in connection with a further embodiment advantageous for both methods, in the form of a flow diagram during the time t increasing downward (on the vertical axis).

First Method

[0088] The first method starts from the known method for aseptic heating of a liquid product P in a heat exchanger unit 22 of the heater zone of an arrangement 20 in a UHT system in which an indirect heat exchange on a wall takes place in the heat exchanger unit 22 between the liquid product P and a heating medium M by a heating medium flow F.sub.M in a heat-releasing heating medium chamber 22.2 being guided countercurrent to a product flow F.sub.P passing through a heat-absorbing product chamber 22.1, with the product flow F.sub.P being heated from a product input temperature T.sub.PE to a product output temperature T.sub.PA and at least the product output temperature T.sub.PA and the heating medium inlet temperature T.sub.ME being monitored and regulated.

[0089] The first method is characterized by the following method steps (A1), (B1), (C), (D1), (E), and (F), which are shown graphically in their conditional relationship and meaning in FIG. 3.

[0090] The method step (A1) includes setting an unknown product-specific temperature curve [T.sub.P(I.sub.x)].sub.PE-PA between the product input temperature T.sub.PE and the product output temperature T.sub.PA with the aid of a supply of the required heating medium flow F.sub.M with the required heating medium inlet temperature T.sub.ME at a heating medium inlet E.sub.M into the heating medium chamber 22.2 and measuring discrete product temperatures T.sub.P or T.sub.P1 to T.sub.Pa at specified measurement points 22.3 in the product flow F.sub.P.

[0091] The method step (B1) includes specifying the product input temperature T.sub.PE at a product input E.sub.P into the product chamber 22.1 and the product output temperature T.sub.PA at a product output A.sub.P from it and providing the heating medium inlet temperature T.sub.ME and the heating medium flow F.sub.M.

[0092] The method step (C) includes measuring a product-specific temperature curve T.sub.P(I.sub.x) between the product output A.sub.P and the product input E.sub.P at the specified measurement points 22.3;

[0093] The method step (D1) includes comparing the temperature curves for method steps (A1) and (C) and calculating temperature deviations T.sub.P at the specified measurement points 22.3.

[0094] The method step (E) includes specifying a permitted temperature deviation [T.sub.P].sub.0.

[0095] The method step (F) includes changing of the heating medium inlet temperature T.sub.ME to a target heating medium inlet temperature T.sub.ME* when the permitted temperature deviation [T.sub.P].sub.0 is exceeded by the calculated temperature deviation T.sub.P.

Second Method

[0096] The second method also starts from the previously described known method and is characterized by the following method steps (A2), (B2), (C), (D2), (E), and (F), with the method steps (C), (E), and (F) being identical to the method steps having the same labels in the first method. The method steps of the second method are also illustrated graphically in FIG. 3 in their conditional relationship and their meaning.

[0097] The method step (A2) includes setting a known product-specific target temperature curve [T.sub.P(I.sub.x)].sub.0 with the aid of measuring discrete product temperatures T.sub.P and T.sub.P1 to T.sub.P, respectively at specified measurement points 22.3 in the product flow F.sub.P and with the aid of a supply of the required heating medium flow F.sub.M with the required heating medium inlet temperature T.sub.ME at a heating medium inlet E.sub.M into the heating medium chamber 22.2.

[0098] The method step (B2) includes specifying the product-specific target temperature curve [T.sub.P(I.sub.x)].sub.0, which includes the product input temperature T.sub.PE at a product input E.sub.P into the product chamber 22.1 and the product output temperature T.sub.PA at a product output A.sub.P out of it, and providing a stored supply of the heating medium flow F.sub.M with a heating medium inlet temperature T.sub.ME.

[0099] The method step (C) includes measuring a product-specific temperature curve T.sub.P(I.sub.x) between the product output A.sub.P and the product input E.sub.P at the specified measurement points 22.3.

[0100] The method step (D2) includes comparing the temperature curves for method steps (A2) and (C) and calculating temperature deviations T.sub.P at the specified measurement points 22.3.

[0101] The method step (E) includes specifying a permitted temperature deviation [T.sub.P].sub.0.

[0102] The method step (F) includes changing of the heating medium inlet temperature T.sub.ME to a target heating medium inlet temperature T.sub.ME* when the permitted temperature deviation [T.sub.P].sub.0 is exceeded by the calculated temperature deviation T.sub.P.

[0103] Both the first and the second method can be advantageously embodied in each case with additional method steps (G), (H), (I), and (J), which are also illustrated graphically in FIG. 3 in their conditional relationship and their meaning.

[0104] The method step (G) includes determining a temperature/time gradient T.sub.ME/t from a change of the heating medium inlet temperature T.sub.ME in a specified time span t.

[0105] The method step (H) includes specifying a reference gradient [T.sub.ME/t].sub.0 for a permitted temperature increase of the heating medium inlet temperature T.sub.ME in the time span t.

[0106] The method step (I) includes comparing the results of the method step (G) with the specification according to the method step (H).

[0107] The method step (J) includes changing the heating medium flow F.sub.M to a target heating medium flow F.sub.M* when the reference gradient [T.sub.ME/t].sub.0 is exceeded by the temperature/time gradient T.sub.ME/t determined.

[0108] Analogous to the representation in FIG. 2, the temperature curves T.sub.P(I.sub.x) and T.sub.M(I.sub.x) shown in FIG. 5 are observed during the operation time of the heat exchanger unit 22, entered over the variable heat exchanger path I.sub.x. The product-specific temperature curve in the specified, heat-absorbing product flow F.sub.P to be treated between the product input temperature T.sub.PE (for example, 125 C.) provided by the upstream process unit 21 and the product output temperature T.sub.PA (for example, 140 C.) necessary to ensure sufficient aseptic heating is designated in turn by T.sub.P(I.sub.x). T.sub.M(I.sub.x) is the designation for two heating medium-specific temperature curves in the heat-releasing heating medium flow F.sub.M. The lower temperature curve, with reference to the position in the drawing, between a third heating medium inlet temperature T.sub.ME(3) (for example, 141.7 C.) and a third heating medium outlet temperature T.sub.MA(3) (for example, 128.8 C.) is at the beginning of the operation time if the heat exchanger unit 22 is still free of any deposits (product fouling) on the product side.

[0109] At the end of the operation time, after 12 hours for example, the control and feedback unit 24 has increased the heating medium inlet temperature T.sub.ME so much that a fourth heating medium inlet temperature T.sub.ME(4) (for example, 144 C.) is now necessary at the heating medium inlet E.sub.M. The third heating medium outlet temperature T.sub.MA(3) necessarily establishing itself at the heating medium outlet A.sub.M at the beginning of the operation time is essentially dependent on a third mass flow ratio f(3), comprised as a ratio of a third heating medium flow F.sub.M(3) and the product flow F.sub.P on one hand (f(3)=F.sub.M(3)/F.sub.P=1.14) and the other influencing parameters cited above in conjunction with FIG. 2.

[0110] A fourth heating medium outlet temperature T.sub.MA(4) (for example, 134.6 C.) necessarily establishing itself at the heating medium outlet A.sub.M at the end of the operation time is essentially dependent on a fourth mass flow ratio f(4), comprised as a quotient of a fourth heating medium flow F.sub.M(4) and the product flow F.sub.P on one hand (f(4)=F.sub.M(4)/F.sub.P=1.57) and the other influencing parameters cited above in conjunction with FIG. 2.

[0111] At the beginning of the operation time, the heat exchanger unit 22 is operated with a minimum value for the third heating medium flow F.sub.M(3), with which, in conjunction with a minimum value for the third heating medium inlet temperature T.sub.ME(3), it is ensured to achieve and maintain the product output temperature T.sub.PA and the product input temperature T.sub.PE.

[0112] In contrast to the known method, as part of the increase of the heating medium inlet temperature from T.sub.ME(3) to T.sub.ME(4), the heating medium flow F.sub.M is increased from the minimum value F.sub.M(3) to the maximum value F.sub.M(4) in a stepwise or continuous manner. This results in a significantly smaller temperature difference between the product temperature T.sub.P and the heating medium temperature T.sub.M at the product input E.sub.P and heating medium outlet A.sub.M respectively compared to the known method. Advantages in this regard with respect to a lesser buildup for the product input E.sub.P were already described above in conjunction with FIG. 2.

[0113] The specialist recognizes the accumulated product fouling deposit during the operation time from the average logarithmic temperature difference T.sub.M as already described. In the present case, according to this disclosure, at the beginning of the operation time, a third average logarithmic temperature difference T.sub.M(3) is 2.6 C. and at the end of the operation time a fourth average logarithmic temperature difference T.sub.M(4) is 6.4 C. In this respect, these values correspond approximately to those in the method of prior art.

[0114] In contrast to the known method, equations (2.1) and (2.2) with correspondingly modified parameters yield altogether a lower quantity of accumulation compared to the known method as a result of the significant reduction of the temperature difference throughout the entire heat exchanger path L from T.sub.small(3)=1.7 C. to T.sub.large(3)=3.8 C. (a factor of 2.2) from the beginning of the operation time up to the end of the operation time, then still from T.sub.small(4)=4 C. to T.sub.large(4)=9.6 C. (a factor of 2.4) at the end of the operation time from the product fouling, considered over the entire heat exchange surface A. This circumstance is particularly due at the beginning and in the first half of the operation time where the temperature difference, i.e., the ratio of T.sub.large(3)=3.8 C. to T.sub.small(3)=1.7 C., is only a factor of 2.2, whereas in the known method with T.sub.large(1)=5.6 C. to T.sub.small(1)=0.9 C. it acts on the product fouling with a factor of 6.2.

[0115] A comparison of the relevant data for heat exchange in the known method according to FIG. 2 and the method according to FIG. 5 is shown in the following table.

TABLE-US-00001 Designation FIG. 2 FIG. 5 Unit of measure [ C.] [ C.] Product input temperature T.sub.PE 125.0 T.sub.PE 125.0 Product output temperature T.sub.PA 140.0 T.sub.PA 140.0 Heating medium inlet temperature T.sub.ME(1) 140.9 T.sub.ME(3) 141.7 Heating medium inlet temperature T.sub.ME(2) 144.5 T.sub.ME(4) 144.0 Heating medium outlet temperature T.sub.MA(1) 130.6 T.sub.MA(3) 128.8 Heating medium outlet temperature T.sub.MA(2) 134.2 T.sub.MA(4) 134.6 Small temperature difference T.sub.small(1) 0.9 T.sub.small(3) 1.7 Small temperature difference T.sub.small(2) 4.5 T.sub.small(4) 4.0 Large temperature difference T.sub.large(1) 5.6 T.sub.large(3) 3.8 Large temperature difference T.sub.large(2) 9.2 T.sub.large(4) 9.6 Average logarithmic temperature difference T.sub.M(1) 2.6 T.sub.M(3) 2.6 Average logarithmic temperature difference T.sub.M(2) 6.6 T.sub.M(4) 6.4 Unit of measure [1] [1] Mass flow ratio f(1) 1.43 f(3) 1.14 Mass flow ratio f(2) 1.43 f(4) 1.57

[0116] A product-specific temperature limit curve of the product flow F.sub.P designated in turn in FIG. 5 as T.sub.P(I.sub.x)is theoretical in nature with respect to its linear plot between the product input temperature T.sub.PE and the product output temperature T.sub.PA, just like a linear temperature curve in the heating medium flow F.sub.M, which is not shown, as already indicated above in conjunction with the known method. As FIG. 5 shows, in the method described herein, success was achieved in the context of the available influencing parameters in bringing the actual temperature curve in the product P and in the heating medium M closer together than in the known method.

[0117] FIG. 5 also graphically shows the method steps D1 and D2 respectively and E and F. A permitted downward temperature deviation is designated as [T.sub.P].sub.0 and an upward one with +[T.sub.P].sub.0. This results in a lower temperature limit curve [T.sub.P(I.sub.x)]* and an upper temperature limit curve [T.sub.P(I.sub.x)]**. The product-specific temperature curve T.sub.P(I.sub.x) is measured via the discrete temperatures T.sub.P in the region close to the product output A.sub.P by the arrangement of the temperature measurement points 22.3. Here the first product temperature T.sub.P1 is located at the discrete heat exchanger path I.sub.x1 (T.sub.P(I.sub.x1)) and the second product temperature T.sub.P2 and third product temperature T.sub.P3 are measured in each case at measurement point intervals I one after the other in the direction of flow of the liquid product P. If the product-specific temperature curve T.sub.P(I.sub.x) diverges particularly from this region, then, in accordance with the invention as described above and illustrated in FIG. 3, this is counteracted by the influencing parameters for the target heating medium inlet temperature T.sub.M* and target heating medium flow F.sub.M*.

[0118] As shown in FIG. 6A, the heat exchanger unit 22 is subdivided into multiple sections 22a connected in series to one another. Here, adjacent sections 22a are connected to one another in each case via a first connecting element 32 through which liquid product P flows on the product side and via a second connecting element 33 on the heating medium side, whereby, if required, the respective temperature measurement points 22.3 are provided in a necessary number of first connecting elements 32.

[0119] The instrumental embodiment of the heat exchanger unit 22 is accomplished in a particularly easy manner if it is implemented as a tubular heat exchanger as shown in FIG. 6A, in which the heat-absorbing product chamber 22.1 and the heat-releasing heating medium chamber 22.2 which surrounds the product chamber 22.2 externally preferably have in each case the form of a straight section of tubing. The subdivision of the length of tubing in sections of equal length or also of different lengths results in the sections 22a. Here there are two fundamentally differing embodiments, specifically a first in which the individual section 22a of the tubular heat exchanger 22 is formed on the product side in each case as a monotube 22.1* through which liquid product P flows, said monotube being concentrically enclosed by the heating medium chamber 22.2 in the form of a tube-shaped external jacket as shown in FIG. 6B.

[0120] In the second embodiment, a so-called shell-and-tube heat exchanger 22, the individual section 22a is formed as a tube bundle 22.1** with a number of parallel interior tubes 22.1*** through which liquid product P flows as shown in FIG. 6C. Here these interior tubes 22.1*** are not only arranged in the Meridian level of the heating medium chamber 22.2, which surrounds the interior tubes 22.1*** altogether as a tube-shaped external jacket as shown in a simplifying manner in FIG. 6C, but are also distributed as evenly as possible over the entire cross-section of this external jacket.

[0121] As shown in FIG. 6A, the first connecting element 32 is preferably formed in each case as a connecting bend, for example as a 180 pipe bend, or as a connection fitting with another geometric form which necessarily ensures an interior passage. The second connecting element 33 is designed, for example, in the form of a short pipe connection which connects adjacent external jackets of the heating medium chamber 22.2 to one another in their end region in each case.

[0122] The arrangement of the necessary temperature measurement points 22.3 is very easily possible by the embodiment of the heat exchanger unit 22 shown above in the form of a tubular heat exchanger or shell-and-tube heat exchanger 22 subdivided in sections 22a, because access to the product flow F.sub.P is given directly at defined measurement point intervals I in each case via the first connecting element 32 without needing to reach into the section 22a itself and through the heating medium chamber 22.2 in a complicated manner. The first, second and third product temperatureT.sub.P1, T.sub.P2 and T.sub.P3 respectively are obtained at the temperature measurement points 22.3 in the embodiment example by the respective measuring apparatus for discrete product temperature 25. The arrangement of the associated temperature measurement points 22.3 in the embodiment example is done based on FIG. 4 in such a way that, viewed in the direction of flow of the liquid product P, upstream of the product output A.sub.P and at a defined spacing from it, they are arranged necessarily in series with respect to one another and with defined spacing from one another, specifically with the spacing of the preferably equal length of the section 22a in each case.

[0123] The list of reference numbers used in the drawing figures is as follows. [0124] 10 arrangement according to prior art [0125] 21 upstream process unit [0126] 22 heat exchanger unit [0127] 22.1 heat-absorbing product chamber [0128] 22.2 heat-releasing heating medium chamber [0129] 23 downstream process unit [0130] 24 control and feedback unit [0131] 26 measuring apparatus for product flow (F.sub.P) [0132] 28.1 measuring apparatus for product input temperature (T.sub.PE) [0133] 28.2 measuring apparatus for product output temperature (T.sub.PA) [0134] 29 measuring apparatus for heating medium flow (F.sub.M) [0135] 30.1 measuring apparatus for heating medium inlet temperature (T.sub.ME) [0136] 31.1 outlet for target medium inlet temperature (T.sub.ME*) [0137] 31.2 outlet for target heating medium flow (F.sub.M*) [0138] A heat exchange surface (of the heat exchanger unit 22) [0139] A.sub.M heating medium outlet [0140] A.sub.P product output [0141] E.sub.M heating medium inlet [0142] E.sub.P product input [0143] F.sub.M heating medium flow in kg/s, for example [0144] F.sub.M* target heating medium flow [0145] F.sub.M(1) first heating medium flow [0146] F.sub.M(2) second heating medium flow [0147] F.sub.P product flow in kg/s, for example [0148] L total heat exchanger path [0149] M heating medium [0150] P liquid product [0151] Q heat flow, for example in W=J/s [0152] T.sub.M heating medium temperature [0153] T.sub.M(I.sub.x) heating medium-specific temperature curve, general [0154] T.sub.MA heating medium outlet temperature, general [0155] T.sub.MA(1) first heating medium outlet temperature [0156] T.sub.MA(2) second heating medium outlet temperature [0157] T.sub.ME heating medium inlet temperature, general [0158] T.sub.ME* target heating medium inlet temperature, general [0159] T.sub.ME(1) first heating medium inlet temperature [0160] T.sub.ME(2) second heating medium inlet temperature [0161] T.sub.P product temperature [0162] T(I.sub.x) product-specific temperature curve, general [0163] T.sub.P(I.sub.x) product-specific temperature limit curve [0164] T.sub.P(I.sub.x1) discrete temperature of the liquid product [0165] T.sub.PA product output temperature [0166] T.sub.PE product input temperature [0167] T.sub.large(1) first large temperature difference [0168] T.sub.large(2) second large temperature difference [0169] T.sub.small(1) first small temperature difference [0170] T.sub.small(2) second small temperature difference [0171] T.sub.m average logarithmic temperature difference, general [0172] T.sub.M(1) first average logarithmic temperature difference [0173] T.sub.M(2) second average logarithmic temperature difference [0174] c.sub.M specific heat capacity of the heating medium (M)in J/(kgK) for example [0175] c.sub.P specific heat capacity of the liquid product (P)in J/(kgK) for example [0176] F mass flow ratio, general [0177] f(1) first mass flow ratio [0178] f(2) second mass flow ratio [0179] K heat transfer coefficient, for example in W/(m.sup.2K)=J/(m.sup.2 sK); K=Kelvin [0180] I.sub.x variable heat exchanger path [0181] I.sub.x1 discrete heat exchanger path (at the point I.sub.x1) [0182] A1 setting of an unknown product-specific temperature curve [T.sub.P(I.sub.x)].sub.PE-PA [0183] A2 setting of a known product-specific target temperature curve [T.sub.P(I.sub.x)].sub.0 [0184] B1 specifying the product input temperature T.sub.PE and the product output temperature T.sub.PA and providing the heating medium inlet temperature T.sub.ME and heating medium flow F.sub.M [0185] B2 specifying the known product-specific target temperature curve [T.sub.P(I.sub.x)].sub.0 and providing the heating medium flow F.sub.M with a heating medium inlet temperature T.sub.ME [0186] C measurement of a product-specific temperature curve T.sub.P(I.sub.x) [0187] D1 comparing the temperature curves for the method steps (A1) and (C) and calculating temperature deviations T.sub.P [0188] D2 comparing the temperature curves for method steps (A2) and (C) and calculating temperature deviations T.sub.P [0189] E specifying a permitted temperature deviation [T.sub.P].sub.0 [0190] F changing the heating medium inlet temperature T.sub.ME [0191] G determining a temperature/time gradient T.sub.ME/t [0192] H specifying a reference gradient [T.sub.ME/t].sub.0 [0193] I comparing the results of method step (G) with the specification according to method step (H); [0194] J changing the heating medium flow F.sub.M [0195] 20 arrangement [0196] 22a Section [0197] 22.1* Monotube [0198] 22.1** tube bundle [0199] 22.1*** interior tube [0200] 22.3 temperature measurement point [0201] 25 measuring apparatus for discrete product temperature T.sub.P; T.sub.P1 to T.sub.Pn [0202] 27.1 measuring apparatus for product inlet pressure (p.sub.E) [0203] 27.2 measuring apparatus for product outlet pressure (p.sub.A) [0204] 30.2 measuring device for heating medium outlet temperature (TMA) [0205] 32 first connecting element [0206] 33 second connecting element [0207] F.sub.M(3) third heating medium flow [0208] F.sub.M(4) fourth heating medium flow [0209] T.sub.MA(3) third heating medium outlet temperature [0210] T.sub.MA(4) fourth heating medium outlet temperature [0211] T.sub.ME(3) third heating medium inlet temperature [0212] T.sub.ME(4) fourth heating medium inlet temperature [0213] T.sub.P discrete product temperature, general [0214] T.sub.P1 first product temperature [0215] T.sub.P2 second product temperature [0216] T.sub.P3 third product temperature [0217] T.sub.Pi i.sup.th product temperature [0218] T.sub.Pn n.sup.th product temperature [0219] [T.sub.P(I.sub.x)].sub.PE-PA unknown, product-specific temperature curve between the product input temperature T.sub.PE and the product output temperature T.sub.PA [0220] [T.sub.P(I.sub.x)].sub.0 known product-specific target temperature curve [0221] [T.sub.P(I.sub.x)]* lower temperature limit curve [0222] [T.sub.P(I.sub.x)]** upper temperature limit curve [0223] T.sub.ME/t temperature/time gradient [0224] [T.sub.ME/t].sub.0 reference gradient [0225] T.sub.M(3) third average logarithmic temperature difference [0226] T.sub.M(4) fourth average logarithmic temperature difference [0227] T.sub.large(3) third large temperature difference [0228] T.sub.large(4) fourth large temperature difference [0229] T.sub.small(3) third small temperature difference [0230] T.sub.small(4) fourth small temperature difference [0231] T.sub.P temperature deviation (+: upward; : downward) [0232] [T.sub.P].sub.0 permitted temperature deviation (+: upward; : downward) [0233] f(3) third mass flow ratio [0234] f(4) fourth mass flow ratio [0235] I measurement point interval [0236] p.sub.A product outlet pressure [0237] p.sub.E product inlet pressure [0238] t Time [0239] t time span