Shell-and-tube heat exchanger

FIELD: heating.

SUBSTANCE: shell-and-tube heat exchanger includes a tube bank of variable cross section with alternating coaxial cylindrical sections which are equal as to length and have two different diameters, and divergent and convergent conical sections with optimum opening angles of the diffuser and the confuser, which connect them, and headers with tube sheets. Tubes of the bank have opposite periodic sequence of alternation of conical-and-cylindrical sections relative to each other under conditions of their longitudinal and transverse streamlining. Tubes with straight end sections of similar diameter are located in opposite vertexes of a rectangular of breakdown at in-line arrangement or in vertexes at the triangle base of breakdown of tube sheets at in-line arrangement of the tube bank.

EFFECT: improving heat transfer efficiency of tubular surface; reducing the weight and metal consumption at reduction of overall dimensions of the heat exchanger.

7 dwg

 

The invention relates to heat-exchange technique and can be used to create heat exchangers and devices for industrial and energy purposes, which are based on smooth tubular surface.

The known heat exchanger, containing a bundle of tubes of the same diameter with a triangular or rectangular breakdown and collectors with tubular boards [1, p.7-8, figure 1.1 a; s-26, table]. The disadvantage of such a heat exchanger is low heat transfer efficiency and low compactness of the surface, due to the fact that the tube bundle is made of straight smooth pipe of the same diameter.

The closest technical solution, selected as a prototype, is a shell-and-tube heat exchanger containing longitudinally streamlined chess bundle of heat exchange tubes with periodically repeated along the length diffusore-confused-profile opening angle of the cone and confuser 6-10C, shifted to each other by a half period of the profile diffuser-confuser" [2].

The disadvantage of this shell-and-tube heat exchanger are reduced heat transfer efficiency and increased intensity. Marked low intensity of heat transfer in the pipes due to the weak interaction of a thread formed in the narrow section of the channel at the border confused and diffusors the x parcel with the surface in the area of maximum cross-section at the border of the diffuser and confused plots because of his "breakthrough" and the lack of opportunity more fully to follow the profile of the pipe wall under the conditions of separation and vortex formation. This reduction in the effect of intensification of heat transfer is manifested in the annular space at the outer wrap of the beam adjacent the coolant, since the control action of the form and geometry of the "elementary" tubular cells in structuring stream is not effective enough. In addition, the use of pipes of the specified profile is realized in this technical solution only in the form of chess (triangular) layout of the beam.

The objective of the invention is to increase efficiency of heat transfer tube surface, reducing the metal and increase the compactness of the heat exchanger.

This problem is solved in shell and tube heat exchanger containing a bundle of tubes of variable cross-section with alternating coaxial same along the length of the cylindrical surface with a large d1and smaller d2external diameters (d1>d2and connecting them diffuser and confused areas with optimal angles of the diffuser and confuser and collectors pipe boards, characterized in that the pipes in the bundle have the opposite of ojou relative to each other the frequency of rotation of the conical-cylindrical sections in terms of their longitudinal and transverse flow stream; in this case the axis of the beam pipe with straight end sections of the same diameter d1or d2coincide with the opposite vertices of the rectangle split pipe boards in the corridor linking, or with vertices at the base of the triangle breakdown at chess piping arrangement of the beam, and each layout option in the annular space is winding and the alternating current stream.

During implementation of the invention can be obtained following a feasibility results:

1. Improving the efficiency of heat transfer in the tube bundle due to additional turbulence in the flow, due to the creation of favorable conditions separated flow past the surface in the annular space, and in pipes with optimum conical-cylindrical profile.

2. The reduction step breakdown of tubes in tube plates through the use of profile tubes with different end diameters and the corresponding increase in the compactness of heat transfer surface and reducing the metal of the heat exchanger.

Figure 1 shows a diagram of shell and tube heat exchanger with a corridor linking pipes beam (square breakdown), longitudinal section; figure 2 - cross section A-a in figure 1; figure 3 - cross section B-B in figure 1; figure 4 is a tubular cell of the beam in cross-section A-A; figure 5 is a tubular cell of the beam in the treatment of B-B.

In the case of chess composition pipes beam (equilateral triangular splitting) scheme tubular cells in the corresponding characteristic cross-sections A-a and B-B shown in Fig.6, 7.

Tubular heat exchanger includes a casing 1 in which is placed the tube bundle 2 variable cross-section with alternating coaxial, equal in length, cylindrical surface and 6 of different diameters d1and d2(d1>d2and connecting them diffuser (b) and confused (g) conical sections with optimal angles of the diffuser and confuser, and collectors 3 and tube 4 boards. Shaped tube secured in tube plates straight ends 5 with different diameters, thus ensuring uniform distribution across the section of the annulus of the incoming primary fluid. The tubes with the same end diameters of d1or d2can be located in the opposite vertices of a rectangle or vertices at the base of the triangle split tube plates, forming a corridor (rectangular) with steps s1Kand s2K(figure 4, 5) or chess (triangular) with steps sSand s2sh(6, 7) layout of the beam. Pipes in the beam have opposite relative to each other the frequency of rotation of the conical-cylindrical sections in terms protolog and their cross flow of coolant flow.

The use of bundles of tubes of variable cross-section with the presented configuration in shell-and-tube heat exchangers will allow the intensification of heat transfer and reduction of hydraulic resistance on the outer side due to the favorable effect of foreign tear flow, reducing turbulence losses in the core of the main flow in the annular channels and internal, by generating a flow of non-stationary Microdrives at optimal angles of the diffuser and confused plots of the tubular surface. When this vortex structures formed in the diffuser sections, can be used to activate the processes of heat transfer surface in the cylindrical sections of the channel with a larger diameter d1as well as the effect of increasing the speed of the near-wall layer confused plots in cylindrical sections of the channel of a smaller diameter d2. You can also assume that the specified geometry in-line channel with optimal angles of the conical sections not only provide the minimum possible coefficient of head loss, but will also contribute to partial restoration of the velocity profile and pressure in the transition from the cone section to the confused through the connecting cylindrical pipe.

Prirate shell-and-tube heat exchanger, heat from the primary coolant, passing into the tube longitudinal channels with a complex spatial configuration is transmitted through the walls of the pipes of the secondary coolant flowing inside the pipe channels with periodically alternating conical-cylindrical sections. The result is a positive effect of additional turbulization of the flow and the greatest intensification of heat transfer on both sides of the tubular surface and the overall energy efficiency of the heat exchanger.

Sources of information

1. Bajan P.I. and other Reference heat-exchange apparatus / P.I. Bazhan, G. Canevet, V.M. Seliverstov. - M.: Mashinostroenie, 1989. - 368 S.

2. Copyright certificate SU1763842 A1. Shell-and-tube heat exchanger. - B No. 35, 1992.

Shell-and-tube heat exchanger containing a bundle of tubes of variable cross-section with alternating coaxial, equal in length, cylindrical surface with a large d1and smaller d2external diameters (d1>d2and connecting them diffuser and confused conical sections with optimal angles of the diffuser and confuser, and collectors pipe boards, characterized in that the pipes in the beam have opposite relative to each other the frequency of rotation of the conical-cylindrical sections in terms of longitudinal and cross the x flow stream; in this case the axis of the beam pipe with pryamimi integral parts of the same diameter d1or d2coincide with the opposite vertices of the rectangle split pipe boards in the corridor linking, or with vertices at the base of the triangle breakdown at chess piping arrangement of the beam, and each layout option in the annular space is winding and the alternating current flow.



 

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