CN111442681A

CN111442681A - Finned tube and heat exchanger

Info

Publication number: CN111442681A
Application number: CN202010365160.1A
Authority: CN
Inventors: 张国柱; 张钧泰; 谷小兵; 李本锋; 刘忠秋
Original assignee: Datang Environment Industry Group Co Ltd; Datang Beijing Energy Management Co Ltd
Current assignee: Datang Environment Industry Group Co Ltd; Datang Beijing Energy Management Co Ltd
Priority date: 2020-04-30
Filing date: 2020-04-30
Publication date: 2020-07-24

Abstract

The invention provides a finned tube and a heat exchanger, wherein the finned tube comprises a base tube and a plurality of fin groups which are arranged along the axial direction of the base tube and connected with the outer wall of the base tube, and the fin groups are arranged in parallel; the fin group comprises two fins arranged in a mirror image manner; along the length direction of the fins, the fins are divided into three parts, wherein the first part is a windward area, the second part is a backflow area, and the third part is a leeward area; the windward area is provided with a vortex street generator, the backflow area is provided with a backflow blocking device, and the end part of the leeward area is of a fillet structure. The windward area has better heat exchange conditions, and has better heat exchange capability after the vortex street generator is added. The backflow zone is provided with a backflow blocking device, backflow can be reduced, even eliminated, and dust deposition is reduced. The leeward area has poor heat exchange effect and more accumulated dust, so that the backflow structure is a rounded corner structure, and the flow resistance is effectively reduced.

Description

Finned tube and heat exchanger

Technical Field

The invention relates to the technical field of heat exchangers, in particular to a finned tube and a heat exchanger.

Background

Energy is an important basis for the economic and social progress of human beings, and along with the continuous increase of energy consumption in China, energy conservation and emission reduction become a long-term guideline for the economic and social development in China. The proportion of the thermal power plant in the power industry is the largest, and the improvement of the energy utilization efficiency of the thermal power unit is very urgent. The thermal power plant is usually provided with an economizer to recover the waste heat of the flue gas so as to achieve the purpose of energy conservation. It is a common way to increase the heat exchange area of the heat exchange tube by adding fins to enhance heat exchange. The H-shaped finned tube has high fin coefficient, good heat transfer performance and stronger dust deposition resistance, and is widely applied to waste heat boilers, power station boilers and various industrial heat exchangers.

In actual production practice, a large amount of fly ash is carried in flue gas entering a heat exchanger, when the flue gas flows in an H-shaped finned tube bundle, an obvious airflow separation and backflow area appears on the leeward side of the finned tubes, the flue gas flow velocity in the backflow area is low, the heat exchange effect is reduced, and the ash accumulation phenomenon is easy to generate. As the heat conductivity coefficient of the deposited dust is very low, the heat exchange performance of the finned tube is further deteriorated along with the increase of the degree of the deposited dust, and the heat exchanger cannot efficiently and safely operate.

Disclosure of Invention

The first purpose of the invention is to provide a finned tube, which can solve the problem of serious dust deposition of a heat exchanger in the prior art;

a second object of the present invention is to provide a heat exchanger employing the heat exchanger as described above.

The invention provides a finned tube, which comprises a base tube and a plurality of fin groups, wherein the fin groups are arranged along the axial direction of the base tube and connected with the outer wall of the base tube, and the fin groups are arranged in parallel;

the fin group comprises two fins arranged in a mirror image manner;

along the length direction of the fins, the fins are divided into three parts, wherein the first part is a windward area, the second part is a backflow area, and the third part is a leeward area;

the windward area is provided with a vortex street generator, the backflow area is provided with a backflow blocking device, and the end part of the leeward area is of a fillet structure.

Preferably, the backflow blocking device comprises a baffle plate arranged on the fin, and the largest surface of the baffle plate is arranged in parallel with the width direction of the fin.

Preferably, the baffle is arranged close to the base pipe along the width direction of the fin and is positioned at 1/3 of the width direction of the fin;

the length of the baffle plate along the axial direction of the base pipe is 1/4-1/3 of the space between the adjacent fin groups.

Preferably, the vortex street generator is a folded edge arranged at one end of the fin close to the air inlet direction;

the length of the folded edge along the axial longest position of the base pipe is 1/3 times the distance between adjacent fin groups.

Preferably, the angle of attack of the extending direction of the vortex street generator and the direction of the airflow is 10-90 degrees.

Preferably, the area of the windward area is larger than that of the leeward area.

Preferably, the finned tube comprises 2-4 base tubes, and the base tubes are arranged in parallel.

A heat exchanger comprises a shell, wherein the finned tube is arranged in the shell;

along the flowing direction of the airflow, the shell is divided into a dust deposition section and a heat exchange section;

the ash deposition section and the heat exchange section are both provided with an ash blowing device and an ash removal groove.

Preferably, in the shell, the finned tubes are arranged along the horizontal direction, and the axial direction of the finned tubes is perpendicular to the air flow direction;

in the dust deposition section, the arrangement pitch between the finned tubes at the upper part is smaller than that of the finned tubes at the lower part.

Preferably, the number of the soot blowers in the soot deposition section is 2-3 times that in the heat exchange section.

Has the advantages that:

the windward area has better heat exchange conditions, and has better heat exchange capability after the vortex street generator is added. The backflow zone is provided with a backflow blocking device, backflow can be reduced, even eliminated, and dust deposition is reduced. The leeward area has poor heat exchange effect and more accumulated dust, so that the backflow structure is a rounded corner structure, and the flow resistance is effectively reduced.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 is a front view of a finned tube minimal repeating unit provided by an embodiment of the present invention;

FIG. 2 is a top view of a finned tube minimal repeating unit provided by an embodiment of the present invention;

FIG. 3 is a schematic structural diagram of a heat exchanger according to an embodiment of the present invention;

FIG. 4 is a schematic structural view of a staggered finned tube arrangement according to an embodiment of the invention.

Description of reference numerals:

1: a finned tube; 2: a dust accumulation section; 3: a heat exchange section; 5: a soot blower; 6: a dust removing groove; 7: an inlet section; 8: an outlet section;

11: a base pipe; 12: a fin; 13: a vortex street generator; 14: a backflow blocking device; 15: and (4) a round corner structure.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments, and it should be understood that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like, indicate orientations and positional relationships based on those shown in the drawings, and are used only for convenience of description and simplicity of description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be considered as limiting the present invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", may explicitly or implicitly include one or more of the described features. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise. Furthermore, the terms "mounted," "connected," and "connected" are to be construed broadly and may, for example, be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

As shown in fig. 1 to 4, in the present embodiment, a finned tube is provided, wherein the finned tube 1 comprises a base tube 11, and a plurality of fin groups arranged axially along the base tube 11 and connected with the outer wall of the base tube, the fin groups being arranged in parallel. Fin group includes the fin 12 of two mirror image settings, and along the length direction of fin 12, fin 12 divide into the triplex, and the first part is the windward district, and the second part is the backward flow district, and the third part is the leeward district, and the windward district is provided with vortex generator 13, and the backward flow district is provided with backward flow separation device 14, and the tip in leeward district is fillet structure 15.

The windward area has better heat exchange conditions, and the vortex street generator 13 has better heat exchange capability. The backflow zone is provided with a backflow blocking device 14, backflow can be reduced, even eliminated, and dust deposition can be reduced. The leeward area has poor heat exchange effect and more accumulated dust, so the fillet structure 15 is adopted for backflow, and the flow resistance is effectively reduced.

The backflow prevention device comprises a baffle plate arranged on the fin 12, and the largest surface of the baffle plate is arranged in parallel with the width direction of the fin. The baffles arranged on the fins 12 are formed by punching, and the punched structure is turned over to form the baffles. One baffle plate or two baffle plates can be arranged on the fin 12, and when the two baffle plates are arranged on the fin 12, the two baffle plates are respectively positioned on two sides of the fin 12.

The baffles are positioned adjacent to the substrate tube 11 across the width of the fins 12 and at 1/3 across the width of the fins.

The length of the baffle plate in the axial direction of the base pipe 12 is 1/4-1/3 of the spacing between adjacent fin groups.

In the use process of the finned tube, the baffle has a blocking effect on air flow, a backflow area can be reduced, even backflow is eliminated, and dust deposition is reduced.

The vortex generator 13 is a folded edge arranged at one end of the fin 12 close to the air inlet direction, and the length of the folded edge along the longest axial position of the base pipe 11 is 1/3 of the distance between the adjacent fin groups. The attack angle between the extending direction of the vortex street generator 13 and the airflow direction is 10-90 degrees.

The vortex street generator 13 is formed by bending fins, and is easy to manufacture.

The area of the windward area is larger than that of the leeward area. Specifically, the area of the windward area is 2-3 times of the area of the leeward area.

The leeward area has poor heat exchange effect and more accumulated dust, so that the backflow is arranged by adopting a round angle, and the flow resistance is effectively reduced.

The fins 12 integrally move towards the windward area, the area of the windward area is increased, the area of the leeward area is reduced, and the heat exchange effect is further enhanced.

The finned tube 1 comprises 2-4 base tubes 11, and the base tubes 11 are arranged in parallel. Namely, the double H-shaped finned tube, the three H-shaped finned tube and the four H-shaped finned tube are included.

The surface shape of the fin 12 may be rectangular, parallelogram, trapezoidal, or trapezoidal. The inner sides of the fins 12 are provided with arc grooves matched with the outer wall of the base tube 11, and the fins 12 are butted with the base tube 11 through the arc grooves.

In summary, the finned tube provided in the present embodiment includes the following advantages:

the windward area has better heat exchange condition, and the fins far away from the base pipe 11 are deviated to the airflow direction by arranging the vortex generator 13, so that the abrasion of smoke can be effectively coped with, and meanwhile, the curved vortex generator 13 can effectively enhance the heat exchange effect. The backward flow district easily takes place flue gas flow separation and backward flow, the backward flow makes the hot time of flue gas and finned tube increase, backward flow district flue gas temperature is higher, and can not spread the region outside the backward flow region fast, therefore the heat transfer effect descends, backward flow district center flue gas velocity is lower, easily make the particulate matter in the flue gas subside out from the flue gas, it is electrified because of the particulate matter in the granule in the flue gas makes the flue gas with front end heat exchanger friction, consequently easily inhale adsorb to the fin on, accumulate gradually and form the jam, in this embodiment, have the effect of blockking to the air current through the baffle, can reduce the backward flow district or even eliminate the backward flow, reduce the deposition. The leeward district makes this regional flue gas velocity of flow show the decline because blockking of parent tube, so the heat transfer effect is relatively poor, and the deposition is also more, and the fin is whole to the district's removal of facing the wind, can increase the district's area of facing the wind and reduce leeward district area simultaneously, compares with single H type fin, and many H type fins have simple process, and it is convenient to process, characteristics such as welding high efficiency.

Referring to fig. 3, 4, in the present embodiment, there is also provided a heat exchanger comprising a housing in which the finned tube 1 as described above is provided.

Along the circulation direction of air current, the casing divide into deposition section 2 and heat transfer section 3, and deposition section 2 and heat transfer section 3 all are provided with soot blower 5 and deashing groove 6.

The shell further comprises an inlet section 7 and an outlet section 8, wherein the inlet section 7, the dust deposition section 2, the heat exchange section 3 and the outlet section 8 are sequentially arranged along the airflow direction.

The inlet section 7 is of a bell mouth structure, and the larger opening of the inlet section 7 is in butt joint with the dust deposition section 2. The sectional area of a flow channel of the flue gas passing through the inlet section 7 is increased, the flow velocity of the flue gas is reduced, the abrasion of the flue gas to the finned tube 1 is reduced, and meanwhile, dust is easier to gather in a dust accumulation section.

The finned tubes 1 are arranged along the horizontal direction, and the axial direction of the finned tubes 1 is vertical to the air flow direction. In the dust deposition section 2, the arrangement pitch between the upper finned tubes 1 is smaller than that of the lower finned tubes 1.

Due to the influence of gravity, the dust deposition at a lower height is usually more than that at a higher height, so that the distance between the finned tubes 1 is increased to prevent the dust deposition from blocking a flow channel.

The number of the soot blowers 5 in the soot deposition section 2 is 2-3 times of the number of the soot blowers 5 in the heat exchange section 3. And the finned tubes 1 are arranged in a hollow arrangement, namely staggered arrangement of fins is formed.

Experiments show that the abrasion of the pipeline is in direct proportion to the 3 rd power of the flow velocity of the flue gas, so that the area of a flow channel is increased, the flow resistance is increased, the flow velocity of the flue gas can be reduced, the staggered arrangement of fins can further increase the resistance of the flow channel, and the abrasion is reduced; experiments also find that most of dust deposition occurs in the first rows of tube bundles, the tube bundles at the rear part of the flow channel have little chance, therefore, dust deposition cleaning should be carried out on the front rows of tube bundles of the flow channel in time, and since the dust deposition of the front rows of tube bundles is much more serious than that of the rear tube bundles, the dust blowing devices should be arranged more densely at the rear part, and the use frequency is higher than that of the rear row.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. The finned tube is characterized by comprising a base tube and a plurality of fin groups which are arranged along the axial direction of the base tube and connected with the outer wall of the base tube, wherein the fin groups are arranged in parallel;

the fin group comprises two fins arranged in a mirror image manner;

2. The finned tube of claim 1 wherein the backflow barrier means comprises a baffle plate disposed on the fin, the baffle plate having a largest surface disposed parallel to a width direction of the fin.

3. The fin tube of claim 1 or 2, wherein a baffle is provided adjacent to the base tube in the width direction of the fin, and the baffle is located at 1/3 in the width direction of the fin;

4. The finned tube of claim 1 wherein the vortex street generator is a folded edge disposed at one end of the fin near the direction of incoming air;

5. The finned tube of claim 1 or 4 wherein the angle of attack of the direction of extension of the vortex street generator to the direction of air flow is from 10 ° to 90 °.

6. The finned tube of claim 1 or 4 wherein the windward area is greater than the leeward area.

7. The finned tube of claim 1 wherein the finned tube comprises 2 to 4 base tubes arranged in parallel therebetween.

8. A heat exchanger comprising a housing in which a finned tube according to any one of claims 1 to 7 is disposed;

9. The heat exchanger according to claim 1, wherein the finned tubes are arranged in a horizontal direction within the housing, and an axial direction of the finned tubes is arranged perpendicular to an air flow direction;

10. The heat exchanger of claim 1, wherein the number of sootblowers located in the soot deposition section is 2-3 times the number of sootblowers located in the heat exchange section.