RU2272232C1 - Heat exchanger - Google Patents

Abstract

FIELD: heat exchange apparatus.

SUBSTANCE: heat exchanger comprises bank of pipes of the oval cross-section which are secured in the pipe desks and mounted inside the casing. The greater axis of the oval is mounted at an angle 3-5 degrees to the direction of the flow in the interpipe space. The pipes are inclined to the direction of the flow at the same angle or at the alternating angles. The oval cross-section of the pipe is shaped without acute corners and can be made in particular of an ellipse. The thickness of the pipes is constant or variable. For the pipe of elliptic cross-section, the thickness of the pipe wall has a minium along the small axis of the ellipse and has a maximum along the large axis of the ellipse.

EFFECT: enhanced efficiency.

7 cl, 5 dwg

Description

The invention relates to the field of heat engineering, namely to heat exchangers operating primarily on scale-forming and other inlaid media.

Known heat exchangers made of polymer materials with pipes connected to the manifolds of the inlet and outlet of heat-exchanging media, each pipe is made in one piece with the intersecting longitudinal partitions located in it, forming compartments, muffled through one of the ends. The damped compartments have openings on the lateral surface for connection to the annular manifolds for supplying and discharging one of the heat-exchanging media. The partitions are made ribbed or corrugated, and grooved inserts (1) are located in the compartments.

However, these heat exchangers cannot work effectively on media containing various impurities, since the presence of finned or corrugated structural elements and corrugated inserts contributes to the deposition of deposits on them, clogging compartments and other cavities of the heat exchanger.

Heat exchangers are also known for working media containing scale-forming impurities, including a housing in which heat transfer elements are made of a heat-sensitive material with a reversible martensitic transformation having two extreme shapes, and the surface curvature of the element in one extreme form differs from the curvature of the surface of this element in another limit form (2).

However, the operability of such heat exchangers for the destruction of the scale layer depends on the presence of a temperature difference. Requires expensive material with the effect of "memory", and this material only responds to temperature changes and is not sensitive to changes in other parameters of the working environment, such as pressure drops.

The closest technical solution is a heat exchanger containing a bundle of pipes located in the casing, fixed in tube plates, and transverse partitions with radial cuts and adjacent sections of surfaces bent to the opposite sides of the cut line, while the cuts on the partitions are made of different lengths, and the partitions with cuts of greater length are installed first and last along the length of the beam and between partitions with cuts of shorter length (3).

However, the known heat exchanger has the following disadvantages:

- no self-cleaning of pipes and the inner surface of the heat exchanger;

- as a result of scale deposits in the cavity of the heat exchanger, its performance decreases;

- it is necessary to periodically turn off the heat exchanger to conduct cleaning;

- effective heat exchange is not ensured not only because of the formation of scale, but also because of the exclusion of significant fluctuations in the pipes due to the peculiarities of their execution and fastening.

The objective of the present invention is to increase the efficiency of self-cleaning and the intensification of heat transfer.

The essence of the invention lies in the fact that in a heat exchanger containing a bundle of pipes of oval cross-section located in the casing, fixed in pipe boards, and, if necessary, transverse partitions, pipes are installed with the location of the major axis of the oval of the cross section at an angle to the flow direction of the annular medium, in particular 3-5 °. The oval section of the pipe can be made in the form of an ellipse. The cross section of the pipe can also be other geometric shapes, for example any profiles without sharp corners. In this case, the thickness of the pipes can be either constant or variable. When executing a section in the form of an ellipse, the wall thickness can be minimal along the small axis of the ellipse and maximum along the major axis of the ellipse. Pipes with respect to the direction of flow can be arranged uniformly (at the same angle of attack α) or herringbone (with alternating angles of attack of the stream "+ α" and "-α").

Figure 1 presents a General view of the heat exchanger; figure 2 - cross section of the heat exchanger of figure 1; figure 3 shows a typical arrangement of the cross section of the pipe relative to the flow direction of the annular medium; figure 4, 5 shows the options for the location of the pipes in relation to the flow.

The heat exchanger contains a casing 1 with nozzles of the input 2 and output 3 of the annular medium. The casing 1 is closed by a cover 4 with a pipe 5 pipe inlet medium and a cover 6 with a pipe 7 pipe outlet medium. Inside the casing 1, a pipe board 8 is fixed at the inlet of the pipe medium, and a pipe board 9 is fixed at the output of the pipe medium. A tube bundle 10 is placed on the pipe boards 8 and 9, which are fixed at their ends in the pipe board 8 and 9. The pipes 10 are made with an oval transverse section. The pipes 10 are installed with the location of the major axis of the oval section at an angle α (angle of attack) to the flow direction of the annular medium. More specifically, the angle α is 3-5 °. In particular, the oval section of the pipe can be made in the form of an ellipse (elliptical section), although the cross section of the pipe can be other geometric shapes, for example, any profiles without sharp angles. In this case, the thickness of the pipes can be either constant or variable. For example, when executing a section in the form of an ellipse, the wall thickness can be minimal along the axis of the ellipse and maximum along the major axis of the ellipse.

Pipes with respect to the direction of flow can be arranged uniformly (at the same angle of attack α) or herringbone (with alternating angles of attack of the stream "+ α" and "-α").

If necessary, in addition to the heat exchanger can be installed transverse partitions 11.

The heat exchanger operates as follows.

The pipe medium enters through the input pipe 5 and enters the space between the cover 4 and the tube plate 8. Next, the pipe medium passes through the tube bundle 10, enters the space between the tube plate 9 and the cover 6 and is discharged through the pipe 7.

The annular medium enters through the inlet pipe 2 into the cavity of the casing 1, washes the tube bundle 10 and exits through the outlet pipe 3. In this case, heat exchange between the tube medium and the annular medium is carried out. The transverse partitions 11 can change the flow direction of the annular medium.

Since the pipes 10 are made with an oval section with the orientation of the major axis of the oval section at an angle of 3-5 ° to the flow direction of the annular medium, self-oscillations of the pipe occur. The occurrence of self-oscillations of pipes leads to the prevention of scale formation and detachment of deposits formed earlier due to deformation of the longitudinal axis of each pipe, changing the configuration of the pipe cross section and bending-torsional vibrations in the plane of the pipe section. The detachment of deposits and scale also leads to a change in the cross section of the pipes 10 from the initial oval cross section to the deformed cross section and vice versa with the appearance of drops and pressure pulsation of the pipe medium. In addition, there is an intensification of heat transfer due to the movement of the surface of the pipes in the annular medium.

The proposed invention improves the efficiency of self-cleaning and intensifies heat transfer due to self-oscillations of the pipes in the beam and changes in the configuration of the cross section of the pipes.

The expected economic efficiency is 540-960 conventional units (in terms of US dollars) per heat exchanger per year, depending on the type, capacity and medium parameters.

Sources of information taken into account

1. USSR Author's Certificate No. 357446, MKI F 28 F 21/06, publ. 10/31/1972, bull. Number 33.

2. USSR Author's Certificate No. 1778490, MKI F 28 F 19/00, publ. November 30, 1992, bull. Number 44.

3. USSR Author's Certificate No. 1580137, MKI F 28 F 9/22, F 28 D 7/00, publ. 07/23/1990, bull. Number 27.

Claims (8)

1. A heat exchanger containing a bundle of oval cross-section pipes placed in the casing, mounted in tube boards, characterized in that the pipes are installed with a large axis of the oval cross section at an angle to the flow direction of the annular medium equal to 3-5 °. 2. The heat exchanger according to claim 1, characterized in that the pipes with respect to the direction of flow are uniformly located at the same angle of attack of the stream. 3. The heat exchanger according to claim 1, characterized in that the pipes with respect to the flow direction are located by the herringbone with alternating angles of attack of the flow. 4. The heat exchanger according to claim 1, characterized in that the oval section of the pipe has a profile shape without sharp angles. 5. The heat exchanger according to claim 1, characterized in that the oval section of the pipe is made in the form of an ellipse. 6. The heat exchanger according to claim 1, characterized in that the thickness of the pipes is variable. 7. The heat exchanger according to claim 6, characterized in that the wall thickness of the pipe is minimal along the minor axis of the ellipse and maximum along the major axis of the ellipse. 8. The heat exchanger according to claims 1 to 5, characterized in that the thickness of the pipes is made constant.

Images