CN101334248A - Longitudinal spiral inner finned tube - Google Patents

Abstract

The invention discloses a longitudinal spiral inner finned tube, which comprises an outer tube and a core tube that are sheathed concentrically, and an inner fin that is embedded around the tube core between the two, and the inner fin is connected to the outer tube and the core tube. Using brazing connection, the inner fins are bent from corrugated inner finned plates and form a cylindrical longitudinal spiral inner finned tube between the outer tube and the core tube, and the longitudinal spiral inner finned tube is distributed with multiple Longitudinal spiral flow channel; the angle between the corrugated pattern of the corrugated inner fin plate and the horizontal direction is α, where 15°≤α≤85°; the corrugated shape is a continuous periodic function, and its longitudinal height H is the same as that of the outer tube It is equal to the spacing between the core tubes; the greater the viscosity of the medium flowing in the inner fin, the sparser the corrugation, the greater the wavelength λ of the corrugation, the fewer the number of longitudinal spiral flow channels, and the greater α; and vice versa. The invention is simple in structure and easy to process and manufacture, and can effectively reduce the flow resistance in the tube while effectively increasing the heat transfer area in the tube.

Description

Longitudinal spiral inner finned tube

technical field

The invention relates to an enhanced heat transfer element used in heat exchange equipment in oil refining, chemical industry, environmental protection, energy, electric power and other industries, in particular to a longitudinal spiral inner finned tube.

Background technique

Heat exchanger is an important unit equipment in oil refining, chemical industry, environmental protection, energy, electric power and other industries. Usually in the construction of chemical plants, heat exchangers account for about 10-20% of the total investment; especially in refineries, Heat exchangers account for about 35-40% of all process equipment investment, of which shell-and-tube heat exchangers account for 37% of the total heat exchanger market in the world. In the shell-and-tube heat exchanger, how to achieve high efficiency and energy saving of the heat exchanger mainly focuses on how to develop new and efficient enhanced heat transfer elements and further enhance the heat transfer performance of the shell side. The research on enhanced heat transfer elements is the basis for the design and manufacture of new high-efficiency heat exchange equipment. In recent years, the research results of various enhanced heat transfer elements have provided great support for chemical industry, petrochemical industry, power, refrigeration, light industry, metallurgy, electronics and other industries. A variety of new and efficient heat exchange equipment is provided, which creates conditions for the comprehensive utilization of energy in the existing heat exchange system, the technical transformation of heat exchange equipment, and the development of new energy and new equipment.

In the enhanced heat transfer technology, finned tubes are widely used because they greatly increase the heat transfer area and can effectively reduce thermal resistance. Adding fins to the outside of the tube is one of the most common ways to enhance the heat transfer outside the tube. one. Relatively speaking, the research work on enhancing heat transfer with inner finned tubes has been carried out less, especially the corrugated inner finned tubes with inner core tubes.

The corrugated inner finned tube heat exchanger adopts high ribs on the inner wall of the heat exchanger tube to expand the heat transfer surface and enhance the heat transfer efficiency in the tube to achieve the purpose of improving the performance of the heat exchanger. Since the corrugated inner fins are installed in the heat exchange tube, the heat exchange area on the side with the lower surface heat transfer coefficient is significantly increased (the inner finning ratio in the tube is as high as 7.4), which increases the total heat transfer coefficient and improves the The heat transfer efficiency solves the basic problem of unbalanced heat exchange caused by the difference in heat transfer coefficient of the two fluids. In addition to high heat transfer efficiency and remarkable energy-saving effect, the corrugated inner finned tube has the following main advantages: ①It can withstand high temperature and high pressure, and has wide adaptability. The tube material of the inner finned tube heat exchanger can be carbon steel or stainless steel. For the carbon steel inner finned tube heat exchanger, it can work at a wall temperature of 600°C for a long time. It can be used as an air preheater in a power plant, an air or gas preheater in a heating furnace in a steel plant, and an air preheater in a heating furnace in an oil refinery. ②The pipe wall temperature is low and the service life is long. Practice shows that when the flue gas temperature reaches 800°C, the average tube wall temperature of the inner finned tube heat exchanger is 420°C, while the average tube wall temperature of the tubular heat exchanger is 570°C under the same working conditions. Since the temperature of the tube wall of the inner finned tube heat exchanger is lowered, corrosion is prevented and the service life of the heat exchanger is extended. ③The heat exchanger is small in size and occupies a small area. The inner fin tube heat exchanger increases the heat exchange area by adding inner fins in the heat exchanger. While enhancing the heat exchange, the heat exchange area of the light tube is reduced, so that the volume of the whole equipment is greatly reduced, generally 50% to 75% smaller than the conventional heat exchanger, and the floor area is generally 25% to 50% of the conventional heat exchanger. %. Therefore, corrugated inner finned tubes are widely used in many industries where there is a large difference in the convective heat transfer coefficient between the two sides of the heat exchange, such as oil refining, power, chemical industry, refrigeration and many other industries.

A comprehensive analysis of the research on corrugated inner finned tubes found that most of the research focuses on how to effectively increase the heat transfer area of the fins or increase the disturbance of the longitudinal flow of the fluid. Although the heat transfer characteristics of the finned tubes are finally increased, the flow Drag is also significantly increased.

Contents of the invention

The technical problem to be solved by the present invention is to provide a longitudinal spiral inner finned tube, which has a simple structure and is easy to process and manufacture. It can effectively increase the heat transfer area in the tube and effectively reduce the flow resistance.

In order to solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a longitudinal spiral inner finned tube, including an outer tube and a core tube that are concentrically threaded and an inner fin that is embedded around the tube core between the two. The inner fin is connected with the outer tube and the core tube by brazing, and it is characterized in that: the inner fin is bent from a corrugated inner fin plate and forms a cylindrical longitudinal A spiral inner finned tube, the longitudinal spiral inner finned tube is distributed with a plurality of longitudinal spiral flow channels;

The included angle between the corrugated pattern of the corrugated inner fin plate and the horizontal direction is α, wherein 15°≤α≤85°; the corrugated shape of the corrugated is a continuous periodic function, and its longitudinal height H is related to that of the outer tube and core equal spacing between tubes;

The greater the viscosity of the medium circulating in the inner fin, the sparser the corrugation of the corrugated inner fin plate, the greater the wavelength λ of the corrugation, the fewer the number of longitudinal spiral flow channels, and the smaller the α big.

The corrugation is sawtooth, rectangular or sinusoidal.

A plurality of holes or slits are continuously opened on the corrugated inner fin plate.

The holes are circular or polygonal.

The corrugated inner fin plate is copper, steel or aluminum metal plate.

Compared with the prior art, the present invention has the following advantages: 1. It is not only simple in structure, easy to process and manufacture, but also convenient to use and operate; 2. It adopts a longitudinal spiral flow channel, which effectively increases the heat exchange area of the fluid in the tube; 3. Makes the medium flow in the tube The direction is longitudinal spiral rotation, which strengthens the disturbance of the flow boundary layer, promotes the mixing of the boundary layer fluid and the mainstream fluid, and strengthens convective heat transfer; 4. The high-speed rotating fluid in the spiral channel can effectively inhibit the fouling in the pipe, It is more suitable for heat exchange in medium with higher viscosity; 5. By continuously opening holes or slits on the corrugated inner fin plate, the effective destruction of the flow boundary layer and temperature boundary layer of oily high-viscosity fluid can be realized, and the disturbance can be enhanced, thereby effectively strengthening the inner surface of the tube. Convective heat exchange. In a word, the present invention can effectively reduce the flow resistance in the tube while effectively increasing the heat transfer area in the tube, which not only increases the heat transfer characteristics of the corrugated inner finned tube, but also increases the fluidity of the medium flow inside the tube.

The technical solutions of the present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

Description of drawings

Fig. 1 is a schematic structural diagram of the corrugation of the corrugated inner fin plate of the present invention.

Fig. 2 is a schematic diagram of the overall structure of the corrugated inner fin plate of the present invention.

Fig. 3 is a schematic diagram of the overall structure of the present invention.

Explanation of reference signs:

1-outer tube; 2-core tube; 3-inner fin.

Detailed ways

As shown in Fig. 1, Fig. 2 and Fig. 3, the present invention comprises an outer tube 1 and a core tube 2 that are sheathed concentrically, and an inner fin 3 that is embedded around the tube core between the two, and the inner fin 3 and The outer tube 1 and the core tube 2 are connected by brazing. Wherein, the inner fin 3 is formed by bending a corrugated inner fin plate and forms a cylindrical longitudinal spiral inner fin tube between the outer tube 1 and the core tube 2, and the longitudinal spiral inner fin tube A plurality of longitudinal spiral circulation channels are distributed. And the included angle between the corrugated pattern of the corrugated inner fin plate and the horizontal direction is α, wherein 15°≤α≤85°. Moreover, the corrugation shape of the corrugated inner fin plate is a continuous periodic function, and the longitudinal height H of the corrugation is equal to the distance between the outer tube 1 and the core tube 2 . The greater the viscosity of the medium circulating in the inner fin, the sparser the corrugation of the corrugated inner fin plate, the greater the wavelength λ of the corrugation, the fewer the number of longitudinal spiral flow channels, and the smaller the α and vice versa, that is, when the viscosity of the circulating medium is smaller, the corrugations of the corrugated inner fin plate are denser, the wavelength λ of the corrugation is smaller, and the number of the longitudinal spiral flow channels is more, α smaller.

The corrugation of the corrugated inner finned plate is zigzag, rectangular or sinusoidal, and the corrugated inner finned plate can be a metal plate such as copper, steel or aluminum. In this specific embodiment, the ripple is a sinusoidal waveform. In the actual manufacturing process, the metal sheet is processed into a corrugated inner finned plate in a corrugated shape by using a mechanical pressing process, specifically according to the distance between the outer tube 1 and the core tube 2 of the longitudinal spiral inner finned tube to be produced Correspondingly determine the longitudinal height H of the corrugation of the corrugated inner fin plate, that is, the amplitude of the sine wave; after that, determine the wavelength λ of the corrugation of the inner fin plate according to the viscosity of the medium flowing in the inner fin 3, specifically when the flow The greater the viscosity of the medium, the sparser the corrugation of the corrugated inner finned plate, the larger the wavelength λ of the corrugation; and vice versa, that is, the smaller the viscosity of the circulating medium, the denser the corrugated inner finned plate. The wavelength λ of its corrugation is smaller. After the amplitude and wavelength λ of the sine wave corrugation are determined, the corrugated inner finned plate to be processed is determined according to the length of the longitudinal spiral inner finned tube and the diameters of the outer tube 1 and the core tube 2, etc. length and board width. At the same time, during the manufacturing process, the angle between the corrugated pattern and the horizontal direction should be α, where 15°≤α≤85°. Similarly, the angle α is determined correspondingly according to the degree of viscosity of the medium flowing in the inner fin 3, specifically, when the viscosity of the medium flowing is greater, α is larger; vice versa, that is, when the viscosity of the medium flowing is higher hour, the smaller α is. During the manufacturing process of the corrugated inner fin plate, multiple holes or slots can be continuously opened on the corrugated inner fin plate. In this embodiment, the holes can be circular or other polygonal. The multiple holes or slits opened can effectively destroy the flow boundary layer and temperature boundary layer of high-viscosity fluids such as oil without damaging the medium circulation, and enhance the disturbance, thereby effectively strengthening the convective heat transfer in the tube. After that, the processed corrugated inner finned plate is mechanically bent along the longitudinal edge of the plate, so that it finally forms a cylindrical shape by itself, and the corrugated inner finned plate that runs at a certain angle to the horizontal direction, that is, the transverse edge of the plate A longitudinal helical inner fin cylinder with a certain helical angle in the longitudinal direction is formed. Finally, the outer tube 1 , the longitudinal spiral inner fin cylinder formed by the corrugated inner fin plate and the core tube 2 are assembled and welded together by brazing.

The above are only preferred embodiments of the present invention, and do not limit the present invention in any way. All simple modifications, changes and equivalent structural changes made to the above embodiments according to the technical essence of the present invention still belong to the technical aspects of the present invention. within the scope of protection of the scheme.

Claims (5)

1. longitudinal spiral inner fin tube, comprise the outer tube (1) that wears with one heart and core pipe (2) and at the two spaced winding tube core around the inner fin that is embedded (3), adopt soldering to be connected between described inner fin (3) and outer tube (1) and the core pipe (2), it is characterized in that: described inner fin (3) is formed by the bending of ripple inner fin plate and form a columned longitudinal spiral formula internally finned tube between outer tube (1) and core pipe (2), is distributed with a plurality of longitudinal spiral formula circulation passages on the described longitudinal spiral formula internally finned tube;

The lines and the angle between horizontal direction of described ripple inner fin Lamb wave line are α, wherein 15 °≤α≤85 °; The bellows-shaped of described ripple is the consecutive periods function, and its vertical panel height H equates with spacing between outer tube (1) and the core pipe (2);

The dielectric viscosity that is circulated in the described inner fin (3) is big more, and the ripple of described ripple inner fin plate is sparse more, and the wavelength X of described ripple is big more, and the quantity of described longitudinal spiral formula circulation passage is few more, and α is big more.

2. according to the described longitudinal spiral inner fin tube of claim 1, it is characterized in that: described ripple is zigzag, rectangle or sinusoidal waveform.

3. according to claim 1 or 2 described longitudinal spiral inner fin tubes, it is characterized in that: have a plurality of holes or many seams continuously on the described ripple inner fin plate.

4. according to the described longitudinal spiral inner fin tube of claim 3, it is characterized in that: described hole is circle or polygon.

5. according to claim 1 or 2 described longitudinal spiral inner fin tubes, it is characterized in that: described ripple inner fin plate is copper, steel or aluminium metal sheet.

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