UHT system and method for heat treating temperature-sensitive food products

Abstract

The invention relates to a UHT system for heat treating temperature-sensitive food products, in particular desserts or dessert-like products, comprising a pre-heating zone and a subsequent high-heating zone. The aim of the invention is to achieve accurate and fast temperature adjustment of the food product leaving the pre-heating zone to the temperature conditions at the inlet of the high-heating zone in a UHT system of the generic type, and at the same time, with an equal dwell time for all partial amounts of the food product, to ensure that the food product is treated in a particularly thermally gentle manner and to keep the mechanical loading of the food product as low as possible.

Claims

1. A method for heat treating temperature-sensitive food products in a UHT system (1), with a pre-heating (VE) and a subsequent high-heating (HE) of the food product (P) to be heated, with a regeneratively generated first heating medium (M1) for the pre-heating (VE), conducted through the UHT system (1) in a first circuit (KL1), and a second heating medium (M2) for high-heating (HE), conducted in a second circuit (KL2), the method comprising the steps of: an entrance temperature of the food product (P) is adjusted to the requirements of the high-heating (HE) before the entry into the high-heating (HE) by additional heating of the first heating medium (M1) by means of a third heating medium (M3), that the additional heating of the first heating medium (M1) takes place before its entry into the pre-heating (VE), that in the area of its additional heating and its subsequent utilization in the pre-heating (VE), the first heating medium (M1) is conveyed with a volume flow (Q) which is increased with respect to the first volume flow (Q.sub.1) of the first heating medium (M1) present in the entire first circuit (KL1) of the UHT system (1), and that all partial amounts of the food product (P) branching and uniting in the pre-heating (VE) and subsequent high-heating (HE) experience the same dwell time at least in the pre-heating (VE).

2. The method according to claim 1, wherein the additional heating of the first heating medium (M1) is limited in time or controllable so as to be limited.

3. The method according to claim 1, wherein the utilization of the additionally heated first heating medium (M1) is limited to a partial area of the pre-heating (VE) disposed immediately upstream of the high-heating (HE).

4. The method according to claim 1, wherein the volume flow (Q) is approximately equal to a second volume flow (Q.sub.2) of the second heating medium (M2) of the high-heating (HE).

5. The method according to claim 1, wherein at the side of the food product (P), the heat transfer conditions in the area of the pre-heating (VE) comprised by the additional heating of the first heating medium (M1) are correspondingly adjusted to the heat transfer conditions at the side of the first heating medium (M1).

6. The method according to claim 1, wherein the respective flow velocity of the food product (P) in the unbranched and the branched flow areas is changed continuously and without jumps, that in the course of the preparation of branching, the flow is at first delayed from a starting value of the unbranched flow, namely the first flow velocity v.sub.0, to a minimum value of the unbranched flow, namely the second flow velocity v.sub.1, and subsequently the flow is accelerated to a maximum value in the course of its branching, namely the third flow velocity v, that the third flow velocity v is greater than the first flow velocity v.sub.0, and that the union of the partial amounts of the food product (P) takes place in an analogously reverse manner.

7. The method according to claim 1, wherein the food product is a dessert.

8. The method according to claim 7, wherein the dessert comprises ingredients containing solid matter.

9. A method for heat treating temperature-sensitive food products comprising: heating said food products with a UHT system, the UHT system comprising; a pre-heating zone (VZ) which has at least one first heat exchanger of the pre-heating zone which is/are impinged by the food product to be heated (P) via a product line (L), and by a regeneratively generated first heating medium (M1) via a first circuit line (K1), with a high-heating zone (HZ) joining the first heat exchanger of the pre-heating zone downstream with respect to the flow direction of the food product (P) and comprising at least one second heat exchanger of the high-heating zone which is/are impinged by the food product (P) via the product line (L), and by a second heating medium (M2) via a second circuit line (K2), with a first line section (L1) which forms a section of the first circuit line (K1) and which supplies the first heating medium (M1) to the first heat exchanger of the pre-heating zone, and with a second line section (L2) which forms a further section of the continuing first circuit line (K1) and which conducts the first heating medium (M1) away from the first heat exchanger of the pre-heating zone (100), wherein the product-conducting heat exchangers of the pre-heating zone and the high-heating zone are each one designed as tube bundle heat exchangers each having at least one tube bundle, and wherein the respective tube bundle consists of a group of parallel connected inner tubes, each flown through by product at the inner side, wherein the first line section (L1) is conducted across a trimming heater heated by means of a third heating medium (M3), a return line (LR) branches off from the second line section (L2) at a branch point (V1), the return line opening into the first line section (L1) at a union point upstream of the trimming heater with respect to the flow direction of the first heating medium (M1) in the first line section (L1), a second conveying device that conveys from the branch point (V1) to the union point (V2) is arranged in the return line (LR), and of the product-conducting heat exchangers of the of the pre-heating zone and the high-heating zone at least the first heat exchanger of the pre-heating zone is designed such that, for the at least one tube bundle, all inner tubes are arranged in the shape of a circular ring, on a single circle (K), and, in an outer channel designed as an annular chamber, they extend in the longitudinal direction of the outer channel and are supported at each end in a tube support plate; adjusting an entrance temperature of the food product (P) to the requirements of the high-heating (HE) before the entry into the high-heating (HE) by additional heating of the first heating medium (M1) by means of a third heating medium (M3); that the additional heating of the first heating medium (M1) takes place before its entry into the pre-heating (VE); that in the area of its additional heating and its subsequent utilization in the pre-heating (VE), the first heating medium (M1) is conveyed with a volume flow (Q) which is increased with respect to the first volume flow (Q.sub.1) of the first heating medium (M1) present in the entire first circuit (KL1) of the UHT system (1); and that all partial amounts of the food product (P) branching and uniting in the pre-heating (VE) and subsequent high-heating (HE) experience the same dwell time at least in the pre-heating (VE).

10. The method according to claim 7, wherein the solid matter comprises whole pieces.

11. The method according to claim 7, wherein the solid matter comprises pulp.

12. The method according to claim 7, wherein the solid matter comprises fibers.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

(1) A delineation of the present invention in more detail will be obtained from the following description and the attached figures of the drawing, as well as from the claims. While the invention is realised in many different embodiments, a preferred example of the realisation of the UHT system and two embodiments of a tube bundle heat exchanger advantageously utilized in the UHT system of the present invention are depicted in the drawing, and described with respect to construction and function below.

(2) FIG. 1 shows a relevant partial area of the UHT system of the present invention in a schematic depiction, which is reduced to essential features;

(3) FIG. 2 shows a first embodiment of a tube bundle heat exchanger preferably utilized in the UHT system according to FIG. 1, in a meridional section;

(4) FIG. 2a shows in a view the tube bundle heat exchanger according to FIG. 2, when the direction of the view towards the depiction according to FIG. 2 takes place from the right side, the second heat exchanger flange arranged at the right side being removed from the associated tube support plate;

(5) FIG. 2b shows in a magnified depiction a detail indicated by X in the meridional section according to FIG. 2a, in the area of the ends of the inner tubes ending in the tube support plate;

(6) FIG. 2c shows a once more magnified depiction of the detail according to FIG. 2b;

(7) FIG. 3 shows a second embodiment of a tube bundle heat exchanger preferably utilized in the UHT system according to FIG. 1, in a meridional section, and

(8) FIG. 3a shows in a view the tube bundle heat exchanger according to FIG. 3, under the conditions for the depiction of FIG. 2a.

DETAILED DESCRIPTION OF THE INVENTION

(9) While this invention may be embodied in many different forms, there are described in detail herein a specific preferred embodiment of the invention. This description is an exemplification of the principles of the invention and is not intended to limit the invention to the particular embodiment illustrated.

(10) A heat-sensitive product P to be subjected to heat treatment, like a dessert or a dessert-like product, enters in the partial area of a UHT system 1 depicted in FIG. 1 into a pre-heating zone VZ via a product line L. The pre-heating zone VZ, in which the food product P experiences a pre-heating VE, is formed by a first heat exchanger 100 of the pre-heating zone and a second heat exchanger 1001 of the pre-heating zone, which is arranged upstream of the former with respect to the flow direction of the food product P. Via a first circuit line K1, both are impinged by a regeneratively generated first heating medium M1, preferably water. The latter is conveyed in the first circuit line K1 in a first circuit KL1 with a first volume flow Q.sub.1, and via a first line section L1, which forms a section of the first circuit line K1, it reaches the first heat exchanger of the pre-heating zone 100, flows through it preferably in reverse flow to the food product P, reaches via a second line section L2, which forms a section of the continuing first circuit line K1, the second heat exchanger of the pre-heating zone 1001 which is also flown through preferably in reverse flow, and leaves the latter via a third line section L3 of the first circuit line K1. In the most general case, the pre-heating zone VZ may consist of 100-(i1) heat exchangers, wherein i takes the values from 1 to n, and is counted so as to increase in the upstream direction with respect to the flow direction of the food product P.

(11) The product line L leaving the pre-heating zone VZ opens into a high-heating zone HZ. The latter, in which the food product P experiences a high-heating HE and becomes a heat-treated food product P, is formed by a first heat exchanger 100+1 of the high-heating zone and a second heat exchanger 100+2 of the high-heating zone, which is arranged downstream of the former with respect to the flow direction of the food product P. By means of a first conveying device 2 and via a second circuit line K2, preferably in reverse flow to the food product P, both are impinged by a second heating medium M2, preferably water, which circulates in a second circuit KL2 with a second volume flow Q.sub.2. In the most general case, the high-heating zone HZ may consist of 100+i heat exchangers, wherein i takes the values of 1 to n and is counted so as to increase in the downstream direction with respect to the flow direction of the food product P.

(12) The product-conducting heat exchangers of the pre- and high heating zone 100-(i1) and 100+i are preferably each designed as tube bundle heat exchangers 100* (see FIGS. 2 to 3a) each having at least one tube bundle 100.i, wherein the respective tube bundle 100.1 consists of a group of parallel connected inner tubes 300, each flown through with product at the inner side.

(13) According to the present invention, the first line section L1 is conducted across a trimming heater 10 heated by means of an externally supplied third heating medium M3. According to the present invention, a return line LR branches off from the second line section L2 at a branch point V1, the return line opens into the first line section L1 at a union point V2 upstream of the trimming heater 10 with respect to the flow direction of the first heating medium M1. A second conveying device 3 that conveys from the branch point V1 to the union point V2 with an additional volume Q is arranged in the return line LR.

(14) While the first heating medium M1 circulates in the first circuit line K1 with the first volume flow Q.sub.1 by means of a not shown conveying device, a volume flow Q, combined from the first volume flow Q.sub.1 and the additional volume flow Q and thus increased with respect to the first volume flow Q.sub.1, results between the branch point V2 and the union point V1, and thus in the trimming heater 10 and in the first heat exchanger 100 of the pre-heating zone. By this volume flow Q, an accurate and speedy temperature adjustment of the food product P leaving the pre-heating zone VZ to the temperature conditions at the entrance of the high-heating zone HZ in the sense of the aims of the present invention is achieved through the cooperation with the additional heating of the first heating medium M1 in the trim heater 10. As a further flanking measure in the sense of the aims of the present invention, improvement of the heat transfer conditions is still proposed at least in the first heat exchanger 100 of the pre-heating zone, in fact at the side of the first heating medium M1 and also at the side of the food product P. This happens on both sides of the heat transition by a methodical increase of the flow velocity in all areas to be flown through.

(15) Of the product-conducting heat exchangers of the pre- and high heating zone 100, 1002, . . . and 100+1, 100+2, . . . , at least the first heat exchanger 100 of the pre-heating zone has congruent flow paths between its product inlet E and its product outlet A penetrated by the entire food product P (see FIG. 2) for all partial amounts of the food product P that branch and unite between the latter. This is materially achieved in that in the at least one tube bundle 100.1, all inner tubes 300 are arranged in the shape of a circular ring on a single circle K in an outer channel 200* designed as an annular chamber, and that they extend in the longitudinal direction thereof and are supported at each end in a tube support plate 700, 800 (see for instance FIG. 2, 2a).

(16) With respect to process engineering, it is ensured by the last mentioned device feature that all the partial amounts of the food product P branching and uniting in the pre-heating VE and the subsequent high-heating HE, respectively, experience the same dwell time at least in the pre-heating VE. With respect to process engineering, it is provided further that the additional heating of the first heating medium M1 is limited in time or controllable so as to be limited. Moreover, the utilisation of the additionally heated first heating medium M1 is limited to a partial area of the pre-heating zone VZ disposed immediately upstream of the high-heating zone HZ and which can preferably be limited to the extent of one heat exchanger. Furthermore, it is advantageous if the volume flow Q is approximately equal to the second volume flow Q.sub.2 of the second heating medium M2 of the high-heating zone HZ.

(17) The tube bundle heat exchanger 100*, normally composed of a plurality of tube bundles 100.1 to 100.n (100.1, 100.2, . . . , 100.i, . . . , 100.n; i=1 to n), wherein an arbitrary tube bundle is designated by 100.i (FIG. 2; see principal construction also in DE 94 03 913 U1), consists in its central portion of an outer shell 200.1 limiting the outer channel 200* and having a first outer shell flange 200a, disposed at the left side with respect to the position in the depiction, which is normally formed in one piece with the first tube support plate 700, and a second outer shell flange 200b, formed and disposed at the right side in the same manner. The tube bundle heat exchanger 100*permits length changes caused by temperature changes if the outer shell flange 200a or 200b is fixedly mounted in its surroundings, and the respective other one is mounted to be freely movable there.

(18) A first transverse channel 400a* opening into a first attachment stub 400a is provided in the area of the right end of the outer shell 200.1, and a second transverse channel 400b* opening into a second attachment stub 400b is provided in the area of the left end of the outer shell 200.1.

(19) A number N of inner tubes 300 extending through the outer channel 200* axis parallel to the outer shell 200.1 and forming an inner channel 300* together, N=14 inner tubes 300 being provided in the realisation example, is supported at each end in the first tube support plate 700 and the second tube support plate 800 (both also called tube area plates), and welded on there at their tube outer diameter and their respective front surfaces.

(20) In order to optimally achieve the partial goal of the invention, i.e. to ensure a thermally particularly gentle treatment of the food product P, which is equivalent to the solution feature of congruent flow paths for all branching and uniting partial amounts of the food product P between their branch point in the product inlet E in an exchanger flange 500, 600 and the point of the union of these partial amounts into the undivided overall flow at the product outlet A in the exchanger flange 600, 500, all the inner tubes 300 are arranged in the shape of a circular ring, on a single circle K in the outer channel 200* designed as an annular chamber. Here they extend in the longitudinal direction thereof and are arranged in the maximum possible perimeter area of the tube support plate 700, 800, preferably at equal distances over the perimeter of the circle K (FIG. 2a, 3a). When the partial goal mentioned above is expressed less sharply, an arrangement of the inner tubes 300 in the shape of a circular ring is also sufficient, where the inner tubes 300 are disposed on two closely neighbouring circles which enclose a relatively great central area free of inner tubes 300.

(21) Radially at the outer side, the first tube support plate 700 merges into the first outer shell flange 200a, and the second tube support plate 800 merges at the outside into the second outer shell flange 200b, wherein tube support plate and outer shell flange 700, 200a and 800, 200b, respectively, each form the one-piece unit mentioned above.

(22) Depending on the arrangement of the respective tube bundle 100.1 to 100.n in the tube bundle heat exchanger 100* and its respective set-up, the inner tubes 300 can be flown through by the food product P either from left to right or reversely with respect to the position in the depiction, wherein the average flow velocity in the inner tube 300, and thus in the inner channel 200*, is designated as the third flow velocity v. In the context of the present invention, the cross sectional dimensioning of the inner tube 300 is made such that this third flow velocity v is at least equal to or preferably significantly higher than a first flow velocity v.sub.0 in a connection arc or a connection fitting 1000, which ends in the first exchanger flange 500 at the one side, and in the second exchanger flange 600 at the other side with respect to the considered tube bundle 100.i. The first exchanger flange 500 is sealed against the unit formed by the first tube support plate 700 and the first outer shell flange 200a via a flange seal 900. For the second exchanger flange 600 and the second tube support plate 800 in connection with the second outer shell flange 200b the situation is analogous.

(23) With respect to the flow direction, the considered tube bundle 100.1 is connected in series to the upstream neighbouring tube bundle 100.i1 and the downstream neighbouring tube bundle 100+1 by the two connections arcs or connection fittings 1000 (normally 180 degree tube arcs) which are depicted in the drawing (FIG. 2) only in outlines. Thus, the first exchanger flange 500 forms the product inlet E for the food product P, and the second exchanger flange 600 houses the associated product outlet A; in the neighbouring tube bundle 100.i1 or respectively 100.i+1, these relations of inlet and outlet are reversed in a corresponding manner.

(24) In the present realisation example, the end areas of the tube bundle heat exchanger 100*, in each case following up the outer channel 200*, are designed reversely identical in shape and with equal dimensions, so that the following description in detail can be limited to one end area, and the corresponding reference signs of the other end region are only quoted. On its side turned away from the associated tube support plate 700, 800, the exchanger flange 500, 600 has an attachment opening 500a, 600a, both corresponding to a standard diameter DN, and thus to a standard opening cross section A.sub.0 of the connection arc or the connection fitting 1000 which is attached there.

(25) The attachment opening 500a, 600a axis symmetrically opens itself in the exchanger flange 500, 600 via a transition 500b, 600b up to an enlarged opening cross section 500c, 600c provided at the ends (FIG. 2c). In this, the latter is designed essentially cylindrical, with an inner diameter D.sub.1 (greatest diameter of the enlarged opening cross section 500c, 600c), wherein the latter is normally dimensioned one to two standard widths greater than the standard diameter DN of the connection arc or the connection fitting 1000 (standard opening cross section A.sub.0 of the connection arc or the connection fitting), and thus correspondingly greater than an overall opening cross section NA.sub.i (FIG. 2a) of all the inner tubes 300 entering into the exchanger flange 500, 600 with number N and a respective tube inner diameter D.sub.i (FIG. 2) and opening cross section A.sub.i. Together with the transition 500b, 600b, the enlarged opening cross section 500c, 600 forms an inner contour K.sub.i, K.sub.i* in the exchanger flange 500, 600.

(26) Coaxially to the attachment opening 500a, 600a and concentric to the tube support plate 700, 800 and fixedly connected to the same is provided an axis symmetrical displacer 11, 12 (FIGS. 2, 2a, 2b, 2c), which forms a ring-shaped channel 500d, 600d with its inner contour K.sub.i K.sub.i* formed by the attachment opening 500a, 600a, the transition 500b, 600b and the enlarged opening cross section 500c, 600c. The ring-shaped channel 500d, 600d increases continuously in its respective ring gap opening cross section from the attachment opening 500a, 600a up to the tube support plate 700, 800.

(27) The displacer 11, 12 is designed in mushroom shape, it consists of a front portion 11a, 12 and a rear portion 11b, 12b ending in a displacer foot 11c, 12c, which form a common maximum outer diameter d.sub.max in the form of a defined flow breakdown point 11d, 12d at their connection cross section (FIGS. 3, 2c). The displacer foot 11c, 12c ends immediately at the tube support plate 700, 800 and there it has an outer diameter d.sub.1.

(28) The inner tubes 300 open into and are flush at each end with a bottom 700b, 800b of an inlet groove 700a, 800a (FIGS. 2c, 2a, 2b), which engages into the tube support plate 700, 800 in the form of a circular deepening from the side of the exchanger flange 500, 600. The bottom 700b, 800b is spaced apart from the front surface of the tube support plate 700, 800 about a recess r. The inlet groove 700a, 800a tapers continuously, preferably symmetrically to the outer diameter of the respective inner tube 300, a concave tapering being preferred.

(29) In order to receive the respective end of the inner tube 300 in the tube support plate 700, 800, an attachment bore 700d, 800d (FIG. 2c) is provided, which ends in the bottom 700b, 800b. The attachment bore 700d, 800d is countersunk in the form of an inlet funnel 700c, 800c engaging into the inlet groove 700a, 800a and continuously tapering towards the inner tube 300 (FIGS. 2a, 3a).

(30) The enlarged opening cross section 500c, 600c merges flush and continuously with its inner diameter D.sub.1 into a flank at the outer side of the inlet groove 700a, 800a, and the displacer foot 11c, 12c merges flush and continuously into a flank at the inner side thereof with its outer diameter d.sub.1 formed at its end.

(31) Thus, the ring gap cross section A.sub.1 in the exchanger flange 500, 600 and in the subsequent tube support plate 700, 800 is determined by the inner diameter D.sub.1 of the enlarged opening cross section 500c, 600c and the outer diameter d.sub.1 of the displacer 11c, 12c, in fact, the ring gap cross section results as A.sub.1=(D.sub.1.sup.2d.sub.1.sup.2)/4. In the context of an advantageous embodiment, the latter is greatest at this point (A.sub.1=A.sub.max).

(32) The call for a loading of the food product P as small as possible in the branching and union of partial amounts is achieved very well if, with respect to the first flow velocity v.sub.0 in the connection arc or the connection fitting 1000, the ring gap cross section A.sub.1 and the opening cross section A.sub.i of the inner tube 300 are dimensioned such that in the ring gap cross section A.sub.1=A.sub.max there is a second flow velocity v.sub.1=v.sub.max=0.5 v.sub.0, and in the opening cross section A.sub.i the third flow velocity v=v.sub.max=1.5 v.sub.0.

(33) The design of the ring-shaped channel 500d, 600d in the exchanger flange 500, 600 and in the respective neighbouring inlet groove 700a, 800a (see FIGS. 2, 2b, 2c) described above has the result that the associated flow velocity of the food product P in the unbranched and the branched flow areas (v.sub.0, v.sub.1, v) is always changed continuously and without jumps. In the course of the preparation of branching, the flow is at first delayed from a starting value of the unbranched flow, namely the first flow velocity v.sub.0, to a minimum value of the unbranched flow, namely the second flow velocity v.sub.1, and subsequently the flow is accelerated to a maximum value in the course of its branching, namely the third flow velocity v. In this, the third flow velocity v is preferably greater than the first flow velocity v.sub.0. The union of the partial amounts of the food product P takes place in an analogously reverse manner.

(34) Depending on the direction of the third flow velocity v in the inner tube 300 or the inner channel 300*, respectively, the food product P to be treated approaches the tube bundle 100.1 to 100.n either via the first attachment opening 500a or the second attachment opening 600a, so that either the first tube support plate 700 or the second tube support plate 800 is approached. Because a heat exchange between the food product P in the inner tubes 300 or the inner channels 300*, respectively, and a first heating medium M1 or a second heating medium M2 in the outer shell 200 or in the outer channel 200* must preferably occur in reverse flow in each case, this heating medium M1, M2 approaches either the first attachment stub 400a or the second attachment stub 400b with a flow velocity in the outer shell c.

(35) If, like this is provided by a preferred embodiment according to FIG. 2, the outer channel 200* designed as a circular chamber is limited at the inner side by an inner shell 200.2 in the form of an inner tube 200.2a, which is supported in the tube support plate 700; 800 at each end, then the inner tubes 300 or the inner channels 300*, respectively, are flown at the outer side with an increased flow velocity c.sub.1, which must be dimensioned systematically and uniformly for all N inner tubes 300. Intensification and improvement of the heat transition in these areas is a consequence of this.

(36) Corresponding flow conditions and heat transition conditions like in the embodiment described above are obtained when the outer channel 200* designed as an annular chamber is limited at the inner side by an inner shell 200.2 in the form of an inner rod 200.2b, which is supported in the respective tube support plate 700; 800 at each end (FIG. 3).

(37) If a limitation of the outer channel 200* by an inner shell 200.2, like depicted in FIGS. 2, 3 and described above, is omitted in the design of the tube bundle heat exchanger 100*of the present invention, then the entire space within the inner tubes 300 arranged on the circle K remains free for the impingement by the heating medium M1, M2. In case that the heat transmission at the side of the heating medium M1, M2 does not form a variable which limits the heat transition in the tube bundle heat exchanger 100*, this simple embodiment can also be utilized in the frame of the present invention.

(38) This completes the description of the preferred and alternate embodiments of the invention. Those skilled in the art may recognize other equivalents to the specific embodiment described herein which equivalents are intended to be encompassed by the claims attached hereto.

LIST OF REFERENCE SIGNS OF THE USED ABBREVIATIONS

(39) FIG. 1 1 UHT system 2 first conveying device 3 second conveying device 10 trimming heater 100 (regenerative) first heat exchanger of the pre-heating zone (i=1) 1001 (regenerative) second heat exchanger of the pre-heating zone (i=2; arranged upstream of the first heat exchanger 100) 100-(i1) generally: regenerative i-th heat exchanger of the pre-heating zone; (i=1 to n; i=4.fwdarw.1003) 100+1 first heat exchanger of the high-heating zone (i=1) 100+2 second heat exchanger of the high-heating zone (i=2; arranged downstream of the first heat exchanger 100+1) 100+i generally: i-th heat exchanger of the high-heating zone; (i=1 to n; i=4.fwdarw.104) HE high-heating HZ high-heating zone K1 first circuit line (for the regenerative first heating medium M1) K2 second circuit line (for the second heating medium M2) KL1 first circuit (regenerative first heating medium M1) KL2 second circuit (second heating medium M2) L product line L1 first line section (of the first circuit line K1) L2 second line section (of the first circuit line K1) L3 third line section (of the first circuit line K1) LR return line (for the regenerative first heating medium M1) M1 (regenerative) first heating medium M1 M2 second heating medium M3 third heating medium 5 P food product (to be heat-treated) P heat-treated food product Q.sub.1 first volume flow (first heating medium M1) Q.sub.2 second volume flow (second heating medium M2) Q (increased) volume flow (first heating medium M1 between V2 and V1) Q additional volume flow (first heating medium M1) VE pre-heating VZ pre-heating zone V1 branch point V2 union point

(40) FIGS. 2 to 3a 11 first displacer 11a front portion 11b rear portion 11c first displacer foot 11d first flow breakdown point 12 second displacer 12a front portion 12b rear portion 12c second displacer foot 12d second flow breakdown point 100* tube bundle heat exchanger in general 100.1, 100.2, . . . , 100.i, . . . . , 100.n tube bundles 100.i i-th tube bundle 100.i+1 arranged downstream of the tube bundle 100.i 100.i1 arranged upstream of the tube bundle 100.i 200.1 outer shell 200* outer channel 200a first outer shell flange 200b second outer shell flange 200.2 inner shell 200.2a inner tube (inner shell) 200.2b inner rod (inner shell) 300 inner tube 300* inner channel 400a first attachment stub 400a* first transverse channel 400b second attachment stub 400b* second transverse channel 500 first exchanger flange 500a first attachment opening 500b first transition 500c enlarged first opening cross section 500d ring-shaped first channel 600 second exchanger flange 600a second attachment opening 600b second transition 600c enlarged second opening cross section 600d ring-shaped second channel 700 first tube support plate (tube area plate) 700a first inlet groove 700b first bottom 700c first inlet funnel 700d first attachment bore 800 second tube support plate (tube area plate) 800a second inlet groove 800b second bottom 800c second inlet funnel 800d second attachment bore 900 flat seal 1000 connection arc/connection fitting c flow velocity in the outer channel, generally c.sub.1 increased flow velocity in the outer channel; (when the opening cross section of the outer channel 200* is reduced) d.sub.1 outer diameter (displacer foot 11c, 12c) d.sub.max greatest outer diameter (displacer 11, 12 25 r recess (of the inner tubes 300) V=v.sub.max third flow velocity (in the inner tube 300) v.sub.0 first flow velocity (in the connection arc/-fitting 1000) v.sub.1=v.sub.min second flow velocity (in the greatest ring gap cross section of the exchanger flange 500, 600 and the tube support plate 700, 800) A product outlet A.sub.i opening cross section (of the inner tube (Ai=D.sub.i.sup.2/4)) NA.sub.i overall opening cross section (of all the parallel flown through inner tubes) A.sub.0 standard opening cross section (of the connection arc/-fitting) A.sub.1=A.sub.max ring gap cross section (greatest cross section (A.sub.1=(D.sub.1.sup.2d.sub.1.sup.2)/4)) D.sub.i tube inner diameter (inner tube 300) D.sub.1 inner diameter (of the enlarged opening cross section 500c, 600c) DN standard diameter (of the connection arc (A.sub.0=DN.sup.2/4)) E product inlet K circle K.sub.i first inner contour K.sub.i* second inner contour N number (of the inner tubes 300)