SU1539027A1 - Method of producing plate-type heat exchangers - Google Patents

Abstract

This invention relates to the manufacture of plate heat exchangers by welding and brazing. The purpose of the invention is to increase the reliability of the connection of the heat exchanger package with the casing and collectors and increase the service life of the heat exchanger in the thermal cycling mode. When assembling a heat exchanger package consisting of alternating sheets 2 and corrugated plates 3 with spacers 4 and solder, use gaskets 4 with shelves protruding along the edges. The height of the shelves exceeds the height of the corrugated plates by an amount equal to the deformation of the gasket material required for their diffusion welding. Solder during assembly is placed in the soldering zones. Solder is used with a soldering temperature exceeding the temperature of diffusion welding of not less than 50 ° C. After assembly, heating, diffusion welding of the gasket shelves, subsequent heating to the brazing temperature and cooling are performed. Then to the package in the area of welded shelves welded casing and manifolds. Pre-diffusion welding of the shelves provides package stiffness, eliminates the effect of solder on the subsequent welding of the casing and increases its efficiency during thermal cycling. 1 hp f-ly, 3 ill.

Description

315

The invention relates to the manufacture of special products by welding and a file, in particular, to methods for producing plate heat exchangers, and can be used in various fields of engineering.

The purpose of the invention is to increase the reliability of the connection of the heat exchanger package with the casing and collectors and increase the service life of the heat exchanger in the thermal cycling mode.

Figure 1 shows a diagram of the package assembly and solder placement; 2 is a separator gasket, a general view; Fig. 3 is a diagram of the assembly and secondary soldering of the block of cores of the core of the heat exchanger.

The method is implemented as follows.

The package 1 of the heat exchanger is assembled through the sheets 2 and corrugated plates 3 with spacers 4 placed along the edges. For assemblies, gaskets 4 are used with the shelves 5 protruding along the edges, the height of which exceeds the height of the corrugated plates 3 and the height of the part 6 of the spacer 4 by an amount equal to the deformation of the gasket material required for their diffusion welding. When assembling, in the zones of the folder, solder 7 is placed with the soldering temperature exceeding the temperature of diffusion welding of the gasket material to not less than 50 ° C. After assembly, the heating is performed to the diffusion welding temperature, the shelves 5 are welded and further heating is continued to the soldering temperature, after which the package 1 is cooled and the casing and collectors are welded (not shown).

When the number of layers of the heat exchanger is more than 10, the heat exchanger can be broken up into individual packages 1 and the number of layers less than 10 that are separately welded, burned, after which the individual packages 1 fall among themselves, forming a complete package of heat exchanger.

The specific features of the gasket shape are due to the fact that inserts are formed with the help of shelves in the process of diffusion welding, which serve to connect the cores of the heat exchanger to the casing and collectors. Large, compared with the plate, the height of the shelf, due to the fact that for quality

Non-diffusion welding of materials requires substantial plastic deformation of the package of connected parts at the temperature and pressure of welding, and at the same time, to obtain a workable product, it is necessary to preserve the shape of the corrugations and sheets that lose stability even at very low pressures and deformations.

Based on experimental data for high-quality bonding by diffusion welding of stainless steel elements such as J1T and Ey 435, the strain value is 0.1-0.15 mm, the welding temperature is 1070 ° C and

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The number of layers n in the cassette should be a multiple of the total number of layers in the heat exchanger and should not (from experience) exceed ten to avoid local loss of stability and uneven deformation of the stack of shelves. In this case, a layer means a closed gas path element consisting of two sheets, a corrugated sheet and two spacers along the edges. Solder grades for soldering are chosen based on the fact that the soldering temperature is higher than not less than 50 ° of diffusion welding temperature. This is necessary in order to eliminate melting of the solder prior to diffusion welding with the corresponding deformation of the shelves, otherwise contact between the soldered surfaces (corrugations and upper sheets) will be absent, there will be no complete adherence to other soldered surfaces soldering. In addition, liquid solder may leak into the gap between the shelves 5, which will reduce the quality of the diffusion joint of the strip pack. The interval is established experimentally, based on the scatter of the properties of solders that vary from batch to batch and the errors of the measurement system (thermocouple error + error of the measuring device controlling the temperature).

To carry out the secondary soldering of the cassette block, the cassette surfaces are coated with solder paste, collected into the block, and secondary soldering is performed in a vacuum chamber.

Prip. Made the heat exchanger of AY A35 stainless steel.

Separating pads were made with shelves whose height exceeded the height of the gallons by 0.15 mm. PRN-58D powdered solder with a soldering temperature of 1120CC was used as the solder.

All parts were degreased in benzit, solder was applied to the soldered areas using acrylic resin, and parts were assembled. Next, the assembled package was placed in a vacuum chamber, made to heat up. welding temperatures of 1050-1070 ° С, welding pressure was applied to the package, pressure was removed, and heating continued to the soldering temperature.

After cooling, the jacket and manifold were welded to the bag and tested.

The use of this method improves the reliability and tightness of the heat exchanger due to the diffusion welding of monolithic inserts and increases its life during thermal cycling by 2-2.5 times due to the absence of a brittle weld between the inserts and the heat exchanger package.

5390276

Claims (2)

1. A method of manufacturing plate heat exchangers, preferably stainless steel, comprising assembling a package of heat exchanger in the form of alternating sheets, corrugated plates and dividing gaskets, placed in soldering zones, JO heating the package to the soldering temperature, cooling and attaching the package and collectors to the package, characterized in that, in order to increase the reliability of the connection between the package of the heat exchanger and the cover and the collectors and increase the service life of the heat exchanger in the thermal cycling mode, gaskets with protruding edges are used. Shelves whose height exceeds the height of the corrugated plates by an amount equal to the deformation of the gasket material required for diffusion welding use solder with a soldering temperature exceeding the temperature The pattern of diffusion welding is not less than on, and in the process of heating the soldering, diffusion welding of the shelves is carried out. 2. Method pop.1, distinguished by 3Q and in that when the number of heat exchanger layers in a package is more than 10, diffusion welding and soldering of the layers are first carried out in separate packages with no more than 10 layers, and then the sheets are soldered again. 15 20 FIG. 2 Fig.Z