METHOD FOR THE THEORETICAL ANALYSIS OF A PROCESS APPARATUS THROUGH WHICH FLUID FLOWS

Abstract

The present invention relates to a method for the theoretical analysis of a process apparatus through which fluid flows, wherein a theoretical, in particular numerical simulation of the apparatus or of at least one part of the apparatus is carried out, wherein at least one element of the apparatus which does not comprise concrete as a material is replaced in the theoretical simulation by at least one concrete element which is manufactured from concrete, and wherein a load analysis of the apparatus is carried out with the aid of the theoretical simulation.

Claims

1. A method for the theoretical analysis of a process apparatus through which fluid flows, wherein a theoretical—in particular, numerical—simulation of the apparatus or of at least one part of the apparatus is carried out, wherein at least one element of the apparatus which does not feature concrete as a material is replaced in the theoretical simulation by at least one concrete element which is manufactured from concrete, and wherein a load analysis of the apparatus is carried out with the aid of the theoretical simulation.

2. The method according to claim 1, wherein a finite element method is carried out as the theoretical simulation of the apparatus or at least one part of the apparatus, and the at least one element is a finite element.

3. The method according to claim 1, wherein the at least one element is at least one contact element through which forces are transmitted between adjacent elements.

4. The method according to claim 1, wherein the at least one element and the at least one concrete element have the same or at least substantially the same properties with regard to force transmission to adjacent elements.

5. The method according to claim 1, wherein the at least one concrete element has the property of transmitting compressive forces completely or at least substantially completely to at least one adjacent element.

6. The method according to claim 1, wherein the at least one concrete element has the property of transmitting tensile forces to at least one adjacent element up to a predeterminable threshold value.

7. The method according to claim 6, wherein the predeterminable threshold value represents a breakage of the apparatus—in particular, an opening of a structure.

8. The method according to claim 6, wherein the predeterminable threshold value represents a leakage of a flange seal and/or represents an opening of layers of the apparatus embodied as a plate heat exchanger and/or represents an opening of a bundle—in particular, at a bundle end—of the apparatus embodied as a coil or wound heat exchanger.

9. The method according to claim 1, wherein a tension, deformation, and/or temperature field analysis of the apparatus is carried out as a load analysis.

10. The method according to claim 1, wherein the process apparatus through which fluid flows is designed as a heat exchanger—in particular, as a plate heat exchanger or coil or wound heat exchanger—or as a column or as a container for phase separation.

11. A computing unit with means for carrying out the method according to claim 1.

12. A computer program that causes a computing unit to carry out the method according to claim 1 when it is executed on the computing unit.

13. A machine-readable storage medium having the computer program according to claim 12 stored thereon.

Description

DESCRIPTION OF FIGURES

[0035] FIG. 1 shows, schematically and in perspective, a process apparatus through which fluid flows designed as a plate heat exchanger, and which can be analyzed in accordance with a preferred embodiment of a method according to the invention.

[0036] FIG. 2 shows a preferred embodiment of a method according to the invention as a block diagram.

DETAILED DESCRIPTION OF THE DRAWING

[0037] FIG. 1 shows an external view of a process apparatus here taking the form of plate heat exchanger 1.

[0038] A computing unit 20, designed, for example, as a control unit, is provided for controlling or regulating the plate heat exchanger. Furthermore, the plate heat exchanger 1 is equipped with a sufficient number of sensors 10, e.g., pressure and/or temperature sensors 10, for detecting measured values for the control or regulation.

[0039] The plate heat exchanger 1 has a cuboid central body 8 with a length of, for example, several meters and a width or height of, for example, approximately one or a few meters. Attachments 6 and 6a are visible on top of the central body 8, on its sides, and underneath the central body 8. The attachments 6 and 6a located underneath the central body 8 and on the side facing away from the side depicted are partially concealed.

[0040] A fluid or process stream can be supplied to or removed again from the plate heat exchanger 1 by connecting pieces 7. The attachments 6 and 6a serve for distributing the fluid introduced through the connecting pieces 7, or for collecting and concentrating the fluid to be removed from the plate heat exchanger 1. The various fluid streams then exchange thermal energy within the plate heat exchanger 1.

[0041] The plate heat exchanger 1 shown in FIG. 1 is designed to feed fluid streams past each other in separate passages for the purpose of heat exchange. Part of the streams can be guided past one another in opposite directions, another part crosswise or in the same direction.

[0042] The central body 8 is essentially an arrangement of separating plates, heat exchange profiles (so-called fins), and distributor profiles. For example, numerous profiles are arranged between and connected to two separating plates. Separating plates and layers with profiles alternate. A layer having a heat exchange profile and distributor profiles is called a passage.

[0043] At the sides of the plate heat exchanger 1, the distributor profiles have distributor profile accesses (so-called headers or half-shells). The fluid may be introduced through these from the outside into the associated passages via the attachments 6 and 6a and connecting pieces 7, or also removed again. The distributor profile accesses are concealed by the attachments 6 or 6a.

[0044] The central body 8 thus has passages and separating plates arranged to be alternately parallel to the flow directions. Both the separating plates and the passages are mostly made of aluminum. To their sides, the passages are closed off by side strips made of aluminum, so that a side wall is formed by the stacking design with the separating plates. The outside passages of the central body 8 are closed off by a cover made of aluminum (cover plate) lying parallel to the passages and the separating plates.

[0045] Such a central body 8 can be produced by, for example, applying a solder to the surfaces of the separating plates and then stacking the separating plates and the passages on top of each other alternately. The covers cover the stack 8 at the top or bottom. The central body is then soldered by heating in an oven.

[0046] During such soldering, a non-uniform temperature distribution within the central body 8 occurs during heating or cooling. Because of the different thermal expansions and the resulting deformation differences, this can lead to gap formations within the central body 8 due to loose or not yet sufficiently firmly connected profiles and separating plates. This can result in problems in the region of the insufficiently soldered layers in the case of later pressure samples. Thus, problems in the interior can occur on, for example, such a soldered block or central body 8 through the formation of dents due to insufficiently soldered areas.

[0047] In the framework of a preferred embodiment of the invention, a theoretical analysis of the plate heat exchanger 1 is to be carried out, e.g., in the course of a planning or design phase, in order to test various design variants of the plate heat exchanger 1 before construction and commissioning and to examine it for improvement potential. In particular, the plate heat exchanger 1 is to be examined in the course of this analysis as to whether and, if so, when an opening or breakage can occur in the form of the gap formations within the central body 8 due to loose or insufficiently connected layers lying on top of one another.

[0048] FIG. 2 shows a preferred embodiment of a method according to the invention as a block diagram.

[0049] In a step 201, a theoretical, numerical simulation of the plate heat exchanger 1 or at least part of the apparatus is carried out. For this purpose, a finite element method is carried out, in the course of which the plate heat exchanger 1 is subdivided into a plurality of individual sub-regions or finite elements, the physical or thermo-hydraulic behavior of which can be calculated on the basis of their simple geometry.

[0050] Individual instances of these finite elements are each part of a separating plate or a profile. The solder contact points between the separating plate and the profile are represented by finite contact elements.

[0051] In the course of conventional numerical simulations, such soldered joints can be numerically simulated with contact elements, by means of which the body contact and the transmission of the forces occurring in the process are computationally detected. However, this can be associated with considerable problems, since the nature of this calculation is non-linear, which can lead to convergence problems and computational terminations. In particular, the insoluble problem can occur here that, for acceptable accuracy, the contact tolerances should ideally be in the range of a few micrometers. However, deformations of the central body may be in the range of millimeters. This can lead to insurmountable hurdles in the course of the computational simulations.

[0052] Within the scope of the method, in step 202, the individual finite elements, which describe a soldered connection of two bodies, are each provided as a finite concrete contact element. The respective replacing concrete element is, in particular, adequate for the replaced element in terms of shape, volume, and mass, but, in contrast to the replaced contact element, is not made of solder, but rather of concrete as a material.

[0053] In step 203, a threshold value is set or predefined in the simulation. Concrete or concrete elements have, in particular, the property of transmitting compressive forces completely, but no or only slight tensile forces, because, otherwise, the concrete breaks. Up to the predefined threshold value, the concrete elements in the finite element simulation transmit tensile forces completely in each case. When the threshold value is reached, the concrete elements no longer transmit tensile forces, and the respective concrete element breaks.

[0054] Thus, in the finite element method, this predeterminable threshold value represents a breakage of the plate heat exchanger 1—in particular, the opening of a structure, viz., the opening or detachment of a passage or a profile from the separating plate, which occurs, in particular, during the heating or cooling of the central body 8.

[0055] The load limit at or above which the concrete element opens or breaks is adjustable.

[0056] In step 204, the finite element method is carried out according to the threshold values predetermined in step 203, and the plate heat exchanger 1 is numerically simulated. With the aid of this theoretical simulation, a load analysis of the plate heat exchanger 1 is carried out—in particular, a tension, deformation, and temperature field analysis.

[0057] In the course of this temperature field analysis, the uneven temperature distribution, in particular, in the central body 8 is simulated and analyzed, which occurs when the soldered connections of separating plates and passages are produced by heating and subsequent cooling. In the course of the tension and deformation analysis, the different thermal expansions in the central body 8 are simulated and analyzed, which may occur because of the uneven temperature distribution. Furthermore, the deformation differences in the central body 8 resulting from the different thermal expansions are simulated and analyzed.

[0058] In particular, it is simulated and analyzed in the course of this load analysis whether the selected design or dimensioning of the simulated plate heat exchanger ultimately results in a gap formation within the central body 8, i.e., in a breakage or loosening of the connection between separating plates and passages, due to the non-uniform temperature distribution, the different thermal expansions, and the deformation differences.

[0059] These finite element method results may be used in step 205 for the manufacture and commissioning of the plate heat exchanger 1, in order to avoid the occurrence of such breakages.