RU2013737C1 - Heat exchanger - Google Patents

Abstract

FIELD: heat power engineering. SUBSTANCE: heat exchanger is provided with transverse partitions which form overflow ports together with the housing for inter-tube medium. Ports have different flow area. Knurling on the surface of the heat exchange tubes is made in form of spherical segments. Gaskets are provided with grooves whose form in longitudinal section is similar to that of the circular segments. These grooves bring tubes in communication with each other. EFFECT: intensification of heat exchange and reduction of hydraulic resistance. 7 cl, 4 dwg

Description

 The invention relates to the field of engineering, in particular to the power system, and can be used in the food industry for the temperature treatment of liquid products, for example for pasteurization of milk.

 Known multi-pass heat exchanger containing a cylindrical body, tube sheets, heat transfer pipes fixed between the tube sheets, transverse partitions placed in the case, inlet and outlet pipes [1].

 The design of the heat exchanger does not provide high efficiency of its work. This is due to the fact that the parallel connection of pipes in sections imposes a restriction on the rate of flow of liquid in them, and therefore on the efficiency of the process of heat transfer.

 Also known is a heat exchanger containing a hollow cylindrical body coated with a layer of thermal insulation and having nozzles for supplying and discharging a heat carrier, tube sheets, heat-exchange tubes with knurling on the surface, end caps and gaskets made of elastic material placed between the end caps and tube sheets [2]. The heat exchange pipes located next to each other are interconnected through grooves in the tube sheets, and ring rolling is made on the pipes. The pipes are connected in series with the formation of at least one flow path of the heated fluid. The disadvantages of this heat exchanger, adopted as a prototype, include the large hydraulic resistance of the heated fluid flow path, which is explained by the presence of ring rolling on the pipes, as well as by the shape of the grooves in the tube boards through which the fluid flows from one pipe to another. The disadvantages of the prototype also include the low efficiency of the heat transfer process, which is explained by the lack of means of turbulization of the movement of the coolant (steam) inside the housing.

 The purpose of the invention is the reduction of hydraulic losses in heat transfer pipes and in the places of their connection, the intensification of the heat transfer process due to turbulization of the movement of the coolant.

This goal is achieved by the fact that the heat exchanger containing a cylindrical body with a layer of insulation and nozzles for input and output of the annular medium, placed in the body is a bundle of interconnected heat exchange pipes having a knurling on the surface and fixed in the openings of the tube sheets, end caps, through elastic gaskets attached to the tube sheets, and nozzles for the input and output of the pipe medium connected to the respective heat exchange tubes, equipped with transverse partitions installed in the inside in a wide space with the formation of annular gaps with heat exchange tubes. The knurling on the surface of the latter is made in the form of spherical segments, and each elastic gasket is made with recesses located on the side of the tube sheet, having in the longitudinal section the shape of circular segments and communicating the heat exchange pipes with each other. It is possible to make a heat exchanger with transverse partitions having different surface areas and forming transfer windows with the body for the annular medium with a cross-sectional area determined from the relation F _n = 0.8 ^n-1 , where n is the number of the partition counting from the closest to the inlet pipe annulus, F _n - the area of the bore of the window formed by the n-th partition. The annular gaps between the partitions and each heat transfer pipe can be made by a value determined from the ratio h = 0.1-0.2 d ₁ , where h is the gap, d ₁ is the outer diameter of the pipe.

, Δ= 0,02-0,05 d₁, t= 0,3-0,5 d₁, где d_с - диаметр основания сферического сегмента, d₁ - наружный диаметр трубы, k - количество сферических сегментов в поперечном сечении последней, Δ - глубина сферических сегментов, t - шаг их расположения вдоль труб.The spherical segments on the surface of the heat exchange pipes can be made with the diameter of their base, depth and pitch along the pipes, determined respectively from the ratios:
d _c =

, Δ = 0.02-0.05 d ₁ , t = 0.3-0.5 d ₁ , where d _c is the diameter of the base of the spherical segment, d ₁ is the outer diameter of the pipe, k is the number of spherical segments in the cross section of the latter , Δ is the depth of the spherical segments, t is the step of their location along the pipes.

The surfaces of the elastic gaskets on the side of the end caps can be conical, while the latter are fastened to the tube sheets using clamps. The recesses in the elastic gaskets may have a longitudinal section in the form of semicircles with a radius determined from the ratio: r ₁ = 1.2-1.4d _o , where d _o is the inner diameter of the pipe in communication with the recess.

 The bottom of each recess of the elastic strip may have a cross-section in the form of a semicircle with a radius equal to half the inner diameter of the pipe.

 Application to the knurling pipes in the form of spherical segments of the indicated sizes allows reducing the hydraulic resistance of the liquid circulation circuit and at the same time intensifying the heat transfer process. The execution of the recesses of the above form in elastic gaskets reduces hydraulic losses during fluid flow from one pipe to another. In addition, gaskets with a conical surface provide more reliable sealing of the housing. Partitions of the indicated sizes provide a constant velocity of the coolant and high turbulence, and therefore, intensify heat transfer. Thus, the distinguishing features of the invention ensure the achievement of the above technical result.

 In FIG. 1 shows a heat exchanger, section BB in FIG. 2; in FIG. 2 is a section AA in FIG. 1; in FIG. 3 - node I in FIG. 1; in FIG. 4 is a section BB in FIG. 1.

The heat exchanger contains a housing 1 with a layer of thermal insulation 2, having nozzles 3 and 4 of the input and output of the annular medium, tube sheets 5, heat transfer tubes 6 with knurling on the surface, end caps 7 and gaskets 8 made of elastic material. On one of the pipes made pipe 9 input pipe medium, and on the other - pipe 10 its output. The pipes are interconnected through recesses 11 in the gaskets 8. Inside the hollow body 1, in the annular space 12, partitions 13 are placed. The surfaces 14 of the gaskets in contact with the end caps 7 are made conical. The surfaces of the covers themselves are made flat. When assembling the cover 7 are bent and fixed in a state of elastic deformation with the help of clamps 15. This allows you to reliably press the gaskets 8 to the tube boards 5. Between the partitions 13 and the heat exchange tubes 6, annular gaps 16. The dimensions of the partitions are selected from the conditions for ensuring the required area of the transfer windows 17 The area F _{1 of the} window 17 formed by a partition located adjacent to the inlet pipe 3 is equal to the area F _{cb of the} passage section of the pipe 3 through which a coolant or cooler is supplied. The area F _{2 of the} hole 17 formed by the next partition is 0.8 F ₁ , etc.

 Consider the operation of the heat exchanger when it is used to pasteurize milk or heat treat any other liquid product.

 The product is fed through the inlet pipe 9 and flows in one or more parallel streams through all the heat transfer pipes. The product is divided (Fig. 1) into two parallel flows in the heat exchange pipe 6, on which the pipe 9 is made. From one pipe to another, the product flows through the recesses 11 in the elastic gaskets 8. In one of the pipes, the flows (if there are several of them) merge and discharge through the outlet pipe 10 made on this pipe.

 The coolant (steam) is supplied to the pipe 3 and through the windows 17 and the gaps 16 moves through sections of the housing. Contacting with the surface of pipes 6, the heat carrier heats the product flowing in them and is discharged through pipe 4. Due to the presence of spherical recesses (holes) on the surface of pipes 6, microvortices (swirling jets) are formed in the product stream, into which the wall masses of the product are sucked. This phenomenon is accompanied by an intensification of the heat transfer process.

Claims (7)

 1. A HEAT EXCHANGER, comprising a cylindrical body with a layer of thermal insulation and nozzles for introducing and outputting the annular medium, a bundle of interconnected heat-exchange pipes having a knurling on the surface and fixed in the holes of the tube sheets, end caps, through elastic gaskets attached to the tube sheets, placed in the body , and nozzles for input and output of the pipe medium connected to the respective heat exchange pipes, characterized in that it is provided with transverse partitions installed in the annular pipe of the space to form annular gaps with the heat exchange tubes, with the knurling on the surface of the latter is in the form of spherical segments, and each elastic pad is formed with recesses spaced from the tube plate, having a longitudinal sectional shape of circular segments and the heat exchange tubes communicates between them. 2. The heat exchanger according to claim 1, characterized in that the transverse partitions are made with different areas of their surfaces, forming with the body transfer windows for the annular medium with a bore area determined from the ratio
F _n = 0.8 ^n-1 · F _cc ,
where n is the number of the septum, counting from the closest to the nozzle of the input annular medium;
F _BB - the area of the passage of the latter;
F _n - the area of the passage section of the window formed by the n-th partition. 3. The heat exchanger according to paragraphs. 1 and 2, characterized in that the annular gaps between the partitions and each heat exchanger pipe have a value
h = 0.1 - 0.2d ₁ ,
where d ₁ is the outer diameter of the pipe. 4. The heat exchanger according to paragraphs. 1 to 3, characterized in that the spherical segments on the surface of the heat exchange pipes are made with a diameter d _from their base, depth Δ and pitch t along the pipes, respectively determined from the relations:
d _c =

;
Δ = 0.02-0.05d ₁ ;
t = 0.3-0.5d ₁ ,
where d ₁ is the outer diameter of the pipe;
k is the number of spherical segments in the cross section of the latter.  5. The heat exchanger according to paragraphs. 1 to 4, characterized in that the surfaces of the elastic gaskets from the end caps are made conical, while the latter are fastened to the tube sheets using clamps. 6. The heat exchanger according to paragraphs. 1 to 5, characterized in that the recesses in the elastic gaskets are made each with a longitudinal section in the form of a semicircle of radius
r ₁ = 1.2 - 1.4 d ₀ ,
where d ₀ is the inner diameter of the pipe in communication with the recess.  7. The heat exchanger according to paragraphs. 1 - 6, characterized in that the bottom of each recess of the elastic strip has a cross-section in the form of a semicircle with a radius equal to half the inner diameter of the pipe.

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