CN112284173A

CN112284173A - Dust deposition prevention heat exchanger

Info

Publication number: CN112284173A
Application number: CN202011183970.1A
Authority: CN
Inventors: 翟慧星; 文夏楠
Original assignee: Beijing University of Civil Engineering and Architecture
Current assignee: Beijing University of Civil Engineering and Architecture
Priority date: 2020-10-29
Filing date: 2020-10-29
Publication date: 2021-01-29

Abstract

The invention provides an anti-ashing heat exchanger, comprising: a heat exchange tube, the heat exchange tube includes a circular tube and an elliptical tube; the elliptical tubes and the circular tubes are arranged in a staggered manner; The long axis of the ellipse corresponding to the cross section of the elliptical tube is twice the length of the short axis of the ellipse corresponding to the cross section of the elliptical tube, and the circumference of the circle corresponding to the cross section of the circular tube is equal to the circumference of the ellipse corresponding to the cross section of the elliptical tube. The heat exchanger of the invention solves the problem of serious ash accumulation in the industrial smoke exhaust waste heat recovery system on the premise that the heat exchanger has better heat transfer performance and lower flow pressure drop.

Description

Dust deposition prevention heat exchanger

Technical Field

The invention relates to the technical field of industrial exhaust smoke waste heat recovery/heat exchangers, in particular to an anti-dust-deposition heat exchanger.

Background

The industrial exhaust gas waste heat energy-saving potential of China is huge. The industrial energy consumption accounts for nearly 70% of the total energy consumption of China, wherein the total waste heat resources account for 17% -67% of the total industrial fuel consumption, the flue gas waste heat accounts for more than 50% of the total industrial waste heat resources, and the flue gas waste heat of part of industrial kilns is even up to 30% -60% of the fuel consumption of the kilns. The waste heat recovery utilization rate of China is less than 20%, and the full recovery and utilization of the industrial exhaust smoke waste heat becomes an important measure for relieving the energy crisis of China and is closely connected with the national economic development.

Industrial exhaust fumes usually contain a large amount of smoke and, even after dust removal, a small amount of fly ash particles. The heat transfer coefficient is reduced due to the deposition of the fly ash particles on the heat exchange surface of the heat exchanger, and the influence on the heat exchanger for recovering the waste heat of the medium-low temperature heat source is more obvious. At present, the accumulated dust is removed by a physical or chemical method after the device for recovering the waste heat of the discharged smoke of a coal economizer of a power plant is shut down, and low-temperature waste heat recovery equipment is coated with an anticorrosive coating, so that the coating can be damaged to a certain extent by physical means such as high-speed dust blowing or a chemical reagent cleaning process, and the service life of a heat exchanger is influenced.

Therefore, in order to reduce the influence of the dust deposition on the heat transfer performance and reduce the damage of the dust removal measure on the heat exchanger, it is urgently needed to develop a heat exchanger with a dust deposition prevention function.

Disclosure of Invention

The invention provides an anti-dust-deposition heat exchanger, which aims to solve the defects in the prior art.

In order to achieve the purpose, the invention adopts the following technical scheme.

The embodiment of the invention provides an anti-dust-deposition heat exchanger, which comprises: the heat exchange tube comprises a circular tube and an elliptical tube; the oval tubes and the round tubes are arranged in a staggered mode, the round tubes are round tubes, the long axis of the cross section of each oval tube corresponding to the oval is 2 times of the length of the short axis of the cross section of each oval tube corresponding to the oval, and the perimeter of the cross section of each round tube corresponding to the round is equal to the perimeter of the cross section of each oval tube corresponding to the oval.

Preferably, the distance between the centers of the adjacent heat exchange tubes is 2 times of the outer diameter of the round tube.

Preferably, the arrangement mode of the heat exchange tubes is a sequential arrangement mode.

Preferably, the elliptical tube is installed in a manner that the major axis of the cross section corresponding to the ellipse is arranged along the downstream direction of the heat exchange fluid outside the tube, and the minor axis of the cross section corresponding to the ellipse is arranged perpendicular to the upstream direction.

According to the technical scheme provided by the dust deposition prevention heat exchanger, the oval tubes and the round tubes are arranged in a staggered mode, the long axis of the cross section of each oval tube is arranged along the downstream direction of the heat exchange fluid outside the tube, and the short axis of the cross section of each oval tube is perpendicular to the incoming flow direction, so that the area of the windward side is reduced, disturbance is enhanced, deposition of dust deposition on the surface of the heat exchange tube can be effectively reduced by adopting the special oval tube, and meanwhile, the dust deposition prevention heat exchanger has good heat transfer performance and lower flow resistance.

Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

FIG. 1 is a schematic structural diagram of an anti-deposition heat exchanger according to the present embodiment;

FIG. 2 is a schematic cross-sectional view of a tubular design and arrangement of the dust deposition prevention heat exchanger according to this embodiment;

fig. 3 is a perspective view illustrating a tubular design and arrangement of the dust deposition prevention heat exchanger according to this embodiment.

Description of reference numerals:

1. a circular tube; 2. an elliptical tube; 3. a flue gas inlet; 4. a housing; 5. a cooling water inlet; 6. a cooling water turn-back region; 7. a flue gas outlet; 8. cooling water outlet

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.

As used herein, the singular forms "a", "an", "the" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may also be present. Further, "connected" or "coupled" as used herein may include wirelessly connected or coupled. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

For the convenience of understanding the embodiments of the present invention, the following description will be further explained by taking several specific embodiments as examples in conjunction with the drawings, and the embodiments are not to be construed as limiting the embodiments of the present invention.

Examples

Fig. 1 is a schematic structural diagram of the dust deposition prevention heat exchanger of the present embodiment, referring to fig. 1, the heat exchanger includes a heat exchange tube, a flue gas inlet 3, a housing 4, a cooling water inlet 5, a cooling water turning-back region 6, a flue gas outlet 7, and a cooling water outlet 8: wherein the heat exchange tube comprises a round tube 1 and an elliptical tube 2.

Fig. 2 is a schematic cross-sectional view of a tubular design and arrangement mode of the dust deposition prevention heat exchanger provided in this embodiment, and fig. 3 is a schematic three-dimensional view of a tubular design and arrangement mode of the dust deposition prevention heat exchanger provided in this embodiment, referring to fig. 2 and fig. 3, the elliptical tubes 2 and the circular tubes 1 are arranged in a staggered manner, the circular tubes 1 are regular circular tubes, the major axes of the cross sections of the elliptical tubes 2 corresponding to the ellipse are 2 times the length of the minor axes of the cross sections of the elliptical tubes corresponding to the ellipse, and the perimeter of the cross sections of the circular tubes 1 corresponding to the circle is equal. 2b is the minor axis of the cross-section of the elliptical tube corresponding to the ellipse, and 2a is the major axis of the cross-section of the elliptical tube corresponding to the ellipse.

Center distance (S) of adjacent heat exchange tubes_L、S_T) Is 2 times of the outer diameter D of the round tube S_LThe tube spacing in the downstream direction, S_TThe tube spacing is perpendicular to the incoming flow direction.

The arrangement mode of the heat exchange tubes is a sequential arrangement mode.

The elliptical tube is installed in a mode that a long axis of the cross section is arranged along the downstream direction of heat exchange fluid outside the tube, and a short axis of the cross section is arranged perpendicular to the upstream direction.

High-temperature industrial exhaust smoke flows into the heat exchanger from the smoke inlet 3, passes through a heat exchange tube bundle consisting of the elliptical tube 2 and the circular tube 1, exchanges heat with cooling water entering the elliptical tube 2 and the circular tube 1 from the cooling water inlet 5 in a cross flow mode, and the smoke subjected to heat exchange flows out of the heat exchanger from the smoke outlet 7; after the cooling water flows through and absorbs the flue gas heat in the oval pipe 2 of front bank and the pipe 1, flows out from oval pipe 2 of front bank and pipe 1, flows into cooling water district 6 of turning back, changes the direction and flows into oval pipe 2 and the pipe 1 of back row afterwards, further absorbs the flue gas heat, and after turning back several times, the cooling water that fully absorbs the flue gas heat flows out from cooling water outlet 8.

The flue gas firstly sweeps the elliptical tube 2 outwards, and the long axis of the cross section ellipse of the elliptical tube 2 is consistent with the flow direction of the flue gas, so that the windward area of the elliptical tube 2 is smaller, and the dust deposition amount of the first row of heat exchange tubes which are most prone to dust deposition is reduced. Then, the smoke sweeps the circular tube 1 outwards, and the windward area of the circular tube 1 is larger than that of the elliptical tube 2, so that the flow velocity of the smoke can be increased when the smoke sweeps the circular tube 1 outwards, disturbance is enhanced, and the heat exchange effect is enhanced. The oval tube 2 and the round tube 1 are combined front and back, the cross section of the combined oval tube 2 and the round tube 1 is formed into water drops along the smoke flowing direction, on one hand, compared with the traditional round tube heat exchanger, the water drop-shaped cross section has better flow linearity and smaller smoke flowing pressure drop, on the other hand, the smoke is inhibited from forming vortex at the tail part of the oval tube 2 and the front part of the round tube 1, and smoke particles carried along with the vortex are reduced from depositing at the front part of the round tube 1 with larger windward area; the connecting line of the circle centers of the adjacent circular tubes is the narrowest section of a flue gas channel, the flue gas flow speed is the fastest, a boundary layer is separated nearby the position to generate a vortex, the vortex carries flue gas particles to be drawn into the front part of the back row elliptical tube 2, and the windward area of the elliptical tube 2 is smaller, so that the ash deposition amount is effectively reduced.

In conclusion, the heat exchanger in the embodiment realizes the function of preventing dust deposition through good pneumatic layout on the premise of taking heat exchange and reducing pressure drop into consideration. Compared with the traditional circular tube heat exchanger, the heat exchanger of the embodiment has obvious dust deposition prevention effect and can reduce the dust deposition by more than half. The pressure drop of the heat exchanger is reduced by about 60%, the heat exchange coefficient is reduced by about 14%, the advantages and disadvantages are overcome on the whole, and due to the fact that the pressure drop is reduced obviously, enough pressure drop space is provided to increase the area of the heat exchanger properly, the reduction of the heat exchange coefficient is compensated, and therefore the best comprehensive performance is achieved.

It will be appreciated by those skilled in the art that the foregoing types of applications are merely exemplary, and that other types of applications, whether presently existing or later to be developed, that may be suitable for use with the embodiments of the present invention, are also intended to be encompassed within the scope of the present invention and are hereby incorporated by reference.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. An anti-deposition heat exchanger, comprising: the heat exchange tube comprises a circular tube and an elliptical tube; the oval tubes and the round tubes are arranged in a staggered mode, the round tubes are round tubes, the long axis of the cross section of each oval tube corresponding to the oval is 2 times of the length of the short axis of the cross section of each oval tube corresponding to the oval, and the perimeter of the cross section of each round tube corresponding to the round is equal to the perimeter of the cross section of each oval tube corresponding to the oval.

2. The heat exchanger of claim 1, wherein the distance between centers of adjacent heat exchange tubes is 2 times the outer diameter of the circular tube.

3. The heat exchanger of claim 1, wherein the heat exchange tubes are arranged in a row-by-row manner.

4. The heat exchanger of claim 1, wherein the oval tubes are mounted such that the major axis of the oval corresponding in cross-section is oriented along the downstream direction of the heat exchange fluid outside the tubes, and the minor axis of the oval corresponding in cross-section is oriented perpendicular to the upstream direction.