阅读说明：本技术 一种电站锅炉热管冷凝端的设计方法 (Design method of condensation end of heat pipe of power station boiler ) 是由 不公告发明人 于 2018-07-20 设计创作，主要内容包括：本发明提供了一种电站锅炉热管冷凝端的设计方法,包括热管、烟气通道和空气通道,所述热管包括蒸发端和冷凝端,所述冷凝端设置在空气通道中；蒸发端设置在烟气通道内；蒸发端吸收烟气通道中烟气的余热,通过冷凝端将热量传递给空气通道中的空气；预热后的空气进入锅炉炉膛进行助燃,其特征在于,所述热管冷凝段设计方法如下：在冷凝端,从热管蒸发端向热管冷凝端方向,均流管的直径不断降低。本发明提供了一种新式的设计方法,本发明可以节省材料,根据压力变化设置均流管,能够保证在流体流动过程中尽快的达到压力均衡。(The invention provides a design method of a heat pipe condensation end of a power station boiler, which comprises a heat pipe, a flue gas channel and an air channel, wherein the heat pipe comprises an evaporation end and a condensation end, and the condensation end is arranged in the air channel; the evaporation end is arranged in the flue gas channel; the evaporation end absorbs the waste heat of the flue gas in the flue gas channel, and the heat is transferred to the air in the air channel through the condensation end; the preheated air enters a boiler hearth for supporting combustion, and the design method of the heat pipe condensation section is as follows: at the condensation end, the diameter of the flow equalizing pipe is continuously reduced from the evaporation end of the heat pipe to the condensation end of the heat pipe. The invention provides a novel design method, which can save materials, is provided with the flow equalizing pipe according to pressure change and can ensure that the pressure is equalized as soon as possible in the flowing process of the fluid.)

1. A design method of a power station boiler heat pipe condensation end comprises a heat pipe, a flue gas channel and an air channel, wherein the heat pipe comprises an evaporation end and a condensation end, and the condensation end is arranged in the air channel; the evaporation end is arranged in the flue gas channel; the evaporation end absorbs the waste heat of the flue gas in the flue gas channel, and the heat is transferred to the air in the air channel through the condensation end; the preheated air enters a boiler hearth for supporting combustion, and the design method of the heat pipe condensation section is as follows:

at the condensation end, the diameter of the flow equalizing pipe is continuously reduced from the evaporation end of the heat pipe to the condensation end of the heat pipe.

2. The method of claim 1 wherein the diameter of the flow equalizer is reduced by a greater and greater magnitude at the condenser end from the evaporator end of the heat pipe to the condenser end of the heat pipe.

3. The method of claim 1, wherein a stabilizing device is disposed within the heat pipe, the stabilizing device being a sheet-like structure disposed across a cross-section of the heat pipe; the stabilizing device is composed of a square through hole and a regular octagonal through hole, the side length of the square through hole is equal to that of the regular octagonal through hole, four sides of the square through hole are respectively sides of four different regular octagonal through holes, and four mutually spaced sides of the regular octagonal through hole are respectively sides of four different square through holes.

4. A power station boiler heat pipe system comprises a heat pipe, a flue gas channel and an air channel, wherein the heat pipe comprises an evaporation end and a condensation end, and the condensation end is arranged in the air channel; the evaporation end is arranged in the flue gas channel.

Technical Field

The invention discloses a part of project which is researched and developed together with enterprises, relates to the field of heat pipe waste heat recovery, and particularly relates to a method and a device for recovering flue gas waste heat by utilizing a heat pipe.

Background

Along with the rapid development of economy in China, the energy consumption is increased day by day, the problem that the urban atmosphere quality is worsened day by day is more prominent, and the problems of saving energy and reducing the emission of harmful substances in the environment are urgent. In the common steam generation process, one of the main reasons of high energy consumption and serious pollution is that the exhaust gas temperature of the boiler flue gas is too high, and a large amount of energy is wasted, so that the waste heat of the boiler tail gas is recycled, the purposes of energy conservation and emission reduction are realized, and the environment can be protected. However, in the prior art, low-temperature corrosion may occur while the residual heat of the flue gas is satisfied, so how to avoid the low-temperature corrosion is an important problem, and meanwhile, if only to avoid the low-temperature corrosion, the residual heat in the flue gas is wasted too much in some cases, so that the residual heat utilization effect is not good, and thus the related problems described above need to be solved urgently.

The heat pipe technology is a heat transfer element called a heat pipe invented by George Grover (George Grover) of national laboratory of Los Alamos (Los Alamos) in 1963, fully utilizes the heat conduction principle and the rapid heat transfer property of a phase change medium, quickly transfers the heat of a heating object to the outside of a heat source through the heat pipe, and the heat conduction capability of the heat transfer element exceeds the heat conduction capability of any known metal. Compared with the most commonly used shell-and-tube heat exchanger in the coal-fired flue gas waste heat recovery, the heat pipe heat exchanger has the advantages of high heat transfer efficiency, compact structure, small pressure loss, being beneficial to controlling dew point corrosion and the like, and has more potential in the coal-fired flue gas waste heat recovery.

In addition, the heat exchange fluid of the heat pipe is a steam-water mixture in the heat exchange process. The heat pipe is in the evaporation process, and inevitable can carry liquid to the steam end in, simultaneously because the exothermic condensation of condensation end to there is liquid in making the condensation end, liquid also can not avoid mixes with steam, thereby makes the fluid in the heat pipe be vapour-liquid mixture, and vapour-liquid mixture exists and leads to the vapour to mix into a whole, and heat transfer capacity descends between the liquid, great influence the efficiency of heat transfer.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides the flue gas waste heat utilization device and the flue gas waste heat utilization method with a novel structure, which fully utilize a heat source, reduce energy consumption and improve the smoke exhaust effect.

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

a power station boiler flue gas waste heat utilization system comprises a heat pipe, a flue gas channel and an air channel, wherein the heat pipe comprises an evaporation end and a condensation end, and the condensation end is arranged in the air channel; the evaporation end is arranged in the flue gas channel; the evaporation end absorbs the waste heat of the flue gas in the flue gas channel, and the heat is transferred to the air in the air channel through the condensation end; the preheated air enters a boiler hearth to support combustion, and the boiler is characterized in that the heat pipes are parallel, and a flow equalizing pipe is arranged between at least two adjacent heat pipes.

Preferably, a plurality of flow equalizing pipes are arranged between adjacent heat pipes from the evaporation ends of the heat pipes to the condensation ends of the heat pipes.

Preferably, at the evaporation end, the distance between adjacent flow equalizing pipes is reduced from the evaporation end of the heat pipe to the condensation end of the heat pipe.

Preferably, a stabilizing device is arranged in the heat pipe, the stabilizing device is a sheet-shaped structure, and the sheet-shaped structure is arranged on the cross section of the heat pipe; the stabilizing device is composed of a square through hole and a regular octagonal through hole, the side length of the square through hole is equal to that of the regular octagonal through hole, four sides of the square through hole are respectively sides of four different regular octagonal through holes, and four mutually spaced sides of the regular octagonal through hole are respectively sides of four different square through holes.

Preferably, the cross-section of the heat pipe is square.

Preferably, the distance between adjacent stabilizers is M1, the side length of the square through hole is C1, the heat pipe is a square section, and the side length of the square section of the heat pipe is C2, so that the following requirements are met:

M1/C2＝a*Ln(C1/C2)+b

wherein a, b are parameters, wherein 1.725< a <1.733,4.99< b < 5.01; 11< C2<46 mm;

1.9<C1<3.2mm；

18<M1<27mm。

preferably, the stabilizer comprises at least one of a square central stabilizer, a square through hole being located at the center of the heat pipe, and a regular octagonal central stabilizer, a regular octagonal through hole being located at the center of the heat pipe.

Preferably, the adjacently arranged stabilizing means are of different types.

The invention has the following advantages:

1) the invention provides a waste heat utilization device with a novel structure, and the uniform pressure, the uniform distribution of fluid flow and the uniform distribution of fluid motion resistance in each heat pipe are ensured by arranging the flow equalizing pipes among the heat pipes.

2) The invention provides a novel electric station boiler waste heat utilization system of a stabilizing device with a novel structure combining a square through hole and a regular octagon through hole, wherein the included angles formed by the edges of the formed square hole and the regular octagon hole are more than or equal to 90 degrees through the square and the regular octagon, so that fluid can fully flow through each position of each hole, and the short circuit of the fluid flow is avoided or reduced. The invention separates the two-phase fluid into liquid phase and gas phase by the stabilizing device with a novel structure, divides the liquid phase into small liquid groups, divides the gas phase into small bubbles, inhibits the backflow of the liquid phase, promotes the smooth flow of the gas phase, plays a role in stabilizing the flow and improves the heat exchange effect. Compared with the stabilizing device in the prior art, the stabilizing device further improves the flow stabilizing effect, strengthens heat transfer and is simple to manufacture.

3) According to the invention, through reasonable layout, the square and regular octagonal through holes are uniformly distributed, so that the fluid on the whole cross street is uniformly divided, and the problem of nonuniform division of the annular structure along the circumferential direction in the prior art is avoided.

4) The invention ensures that the large holes and the small holes are uniformly distributed on the whole cross section by uniformly distributing the square holes and the regular octagonal holes at intervals, and ensures that the separation effect is better by changing the positions of the large holes and the small holes of the adjacent stabilizing devices.

5) According to the invention, the stabilizing device is of a sheet structure, so that the stabilizing device is simple in structure and low in cost.

6) According to the invention, the optimal relation size of the parameters is researched by setting the regular changes of the parameters such as the distance between adjacent stabilizing devices, the side length of the hole of the stabilizing device, the pipe diameter of the heat absorbing pipe, the pipe spacing and the like in the height direction of the heat absorbing pipe, so that the current stabilizing effect is further achieved, the noise is reduced, and the heat exchange effect is improved.

7) The invention realizes the optimal relational expression of the heat exchange effect under the condition of meeting the flow resistance by widely researching the heat exchange rule caused by the change of each parameter of the stabilizing device.

8) The waste heat utilization device with the novel structure is provided, and the uniform pressure, the uniform distribution of the fluid flow and the uniform distribution of the fluid motion resistance in each heat pipe are ensured by arranging the flow equalizing pipe between the heat pipes.

Description of the drawings:

FIG. 1 is a schematic structural diagram of a waste heat utilization system of a power station boiler.

FIG. 2 is a schematic cross-sectional view of a stabilization device according to the present invention;

FIG. 3 is a schematic view of another cross-sectional configuration of the stabilization device of the present invention;

FIG. 4 is a schematic view of the arrangement of the stabilizing device of the present invention within a heat pipe;

FIG. 5 is a schematic cross-sectional view of the arrangement of the stabilization device of the present invention within a heat pipe;

fig. 6 is a schematic cross-sectional view of a heat pipe with a flow equalizer tube according to the present invention.

In the figure: 1. flue gas channel, 11 heat pipe, 2 air channel, 3 flow equalizing pipe, 4 stabilizing device, 41 square through hole, 42 regular octagon through hole and 43 sides

Detailed Description

The utility model provides a boiler flue gas waste heat utilization system, waste heat utilization system includes heat pipe 11, flue gas passageway 1 and air channel 2, heat pipe 11 includes evaporation end 111 and condensation end 112, condensation end 112 sets up in air channel 12, and evaporation end 11 sets up in the flue. The evaporation end 111 absorbs the residual heat of the flue gas in the flue of the boiler, and transfers the heat to the air in the air channel 12 through the condensation end 112. And the preheated air enters a boiler hearth to support combustion.

When the heat pipe is in operation, heat is absorbed from flue gas through the evaporation end 111, then the heat is released to air at the condensation end, fluid is condensed, and then enters the evaporation end 111 under the action of gravity.

In the operation process of the waste heat utilization device, fluid distribution is uneven, in the heat collection process, different heat pipes absorb different heat, so that the temperatures of fluids in different heat pipes are different, and in some heat pipes, even fluid, such as water, is in a gas-liquid two-phase state, and the fluid in some heat pipes is still liquid, so that the pressure in the heat pipes is increased because the fluid is changed into steam, and therefore through arranging the flow equalizing pipes among the heat pipes, the fluid can flow in the heat pipes mutually, the pressure distribution in all the heat pipes is balanced, and the fluid distribution can be promoted to be balanced.

Alternatively, as shown in fig. 6, a flow equalizing pipe 3 is disposed between the heat pipes. A flow equalizing pipe 3 is arranged between at least two adjacent heat pipes 11. In the research, it is found that in the process of heat absorption and heat release of the evaporation tubes, the heat absorption amount and the heat release amount of the heat absorption and heat release tubes at different positions are different, so that the pressure or the temperature between the heat pipes 11 is different, and thus, the temperature of a part of the heat pipes 11 is too high, which results in shortened service life, and once the heat pipes 11 have problems, the problem that the whole waste heat utilization system cannot be used may occur. According to the invention, through a great deal of research, the flow equalizing pipes 3 are arranged on the adjacent heat pipes, so that under the condition that the pressure is different due to different heating of the heat pipes, the fluid in the heat pipe 11 with high pressure can quickly flow to the heat pipe 11 with low pressure, thereby keeping the overall pressure balance and avoiding local overheating or overcooling.

Preferably, a plurality of uniform flow tubes 3 are arranged between adjacent heat pipes 11 from the evaporation end of the heat pipe 11 to the condensation end of the heat pipe 11. Through setting up a plurality of flow equalizing pipes, can make the continuous balanced pressure of fluid in the heat absorption evaporation process, guarantee the pressure balance in the whole heat pipe.

Preferably, at the evaporation end 111, the distance between adjacent uniform flow tubes 3 decreases from the evaporation end of the heat pipe 11 to the condensation end of the heat pipe 11. The purpose is to arrange more flow equalizing pipes, because the fluid continuously absorbs heat along with the upward flow of the fluid, and the pressure in different heat pipes is more and more uneven along with the continuous heat absorption of the fluid, so that the pressure equalization can be ensured to be achieved as soon as possible in the flowing process of the fluid through the arrangement.

Preferably, at the evaporation end 111, the distance between adjacent uniform flow tubes decreases from the evaporation end of the heat pipe 11 to the condensation end of the heat pipe 11 to a greater extent. Experiments show that the arrangement can ensure that the pressure balance is achieved more optimally and more quickly in the fluid flowing process. This is also the best way of communicating by extensively studying the law of change of the pressure distribution.

Preferably, the diameter of the flow equalizing pipe 3 is continuously increased from the evaporation end of the heat pipe 11 to the condensation end of the heat pipe 11 at the evaporation end 111. The purpose is to ensure a larger communication area, because the fluid continuously absorbs heat to generate steam along with the upward flow of the fluid, and the temperature and pressure in different heat pipes are more and more uneven along with the continuous difference of the steam, so that the pressure balance can be ensured to be achieved as soon as possible in the flowing process of the fluid through the arrangement.

Preferably, the diameter of the equalizing pipe 3 increases more and more from the evaporation end of the heat pipe 11 to the condensation end of the heat pipe 11 at the evaporation end 111. Experiments show that the arrangement can ensure that pressure equalization can be achieved more optimally and more quickly in the fluid flowing process. This is also the best way of communicating by extensively studying the law of change of the pressure distribution.

Preferably, at the condensation end 112, the distance between adjacent uniform flow tubes 3 increases from the evaporation end of the heat pipe 11 to the condensation end of the heat pipe 11. The purpose is to arrange fewer flow equalizing pipes and reduce the cost. Because the steam in the heat pipe continuously releases heat and condenses along with the upward lower part of the condensation end 112, and the pressure in the heat pipe is smaller and smaller along with the continuous heat release of the fluid, the phenomenon of non-uniformity is more and more alleviated, therefore, by the arrangement, the material can be saved, and the pressure equalization can be achieved as soon as possible in the flowing process of the fluid by arranging the flow equalizing pipe according to the pressure change.

Preferably, at the condensation end 112, the distance between adjacent uniform flow tubes increases from the evaporation end of the heat pipe 11 to the condensation end of the heat pipe 11. Experiments show that the arrangement can ensure that the pressure balance is achieved more optimally and more quickly in the fluid flowing process. This is also the best way of communicating by extensively studying the law of change of the pressure distribution.

Preferably, the diameter of the flow equalizing pipe 3 at the condensation end 112 decreases from the evaporation end of the heat pipe 11 to the condensation end of the heat pipe 11. The purpose is to ensure reduced communication area and reduce cost. The same principle as the distance from the front is increasing.

Preferably, the diameter of the flow equalizing pipe 3 is gradually reduced from the evaporation end of the heat pipe 11 to the condensation end of the heat pipe 11 at the condensation end 112 to a larger extent. Experiments show that the arrangement can ensure that the pressure balance is achieved more optimally and more quickly in the fluid flowing process. This is also the best way of communicating by extensively studying the law of change of the pressure distribution.

Because the heat transfer of steam in the heat pipe, make the heat pipe vapour-liquid two-phase flow appear, on the one hand, the heat pipe is in the evaporation process, inevitable can carry liquid to the heat pipe in, simultaneously because the exothermic condensation of condensation end, thereby make to have liquid in the condensation end, liquid is inevitable among the entering steam, thereby make the fluid in the heat pipe be vapour-liquid mixture, simultaneously the heat pipe can be because of the incondensable gas that ageing produced at the operation in-process, the condensation end on the heat pipe upper portion is generally risen to incondensable gas, the existence of incondensable gas leads to the pressure increase in the heat pipe condensation end, pressure makes liquid flow in the heat pipe. Greatly influencing the heat exchange efficiency. Therefore, the present invention adopts a new structure to separate vapor phase and liquid phase, so that the heat exchange is enhanced.

A stabilizing device 4 is arranged in the heat pipe, and the structure of the stabilizing device 4 is shown in figures 2 and 3. The stabilizing device 4 is a sheet-like structure which is arranged on the cross section of the heat pipe 11; the stabilizing device 4 is composed of a square and regular octagonal structure, thereby forming a square through hole 41 and a regular octagonal through hole 42. The side length of the square through-hole 41 is equal to the side length of the regular octagonal through-hole 42 as shown in fig. 2, the four sides 43 of the square through-hole are the sides 43 of four different regular octagonal through-holes, respectively, and the four sides 43 of the regular octagonal through-hole, which are spaced apart from each other, are the sides 43 of four different square through-holes, respectively.

The invention adopts a stabilizing device with a novel structure, and has the following advantages:

1) the invention provides a novel structure stabilizing device combining a square through hole and a regular octagon through hole, wherein the included angles formed by the edges of the formed square hole and the regular octagon hole are larger than or equal to 90 degrees through the square hole and the regular octagon hole, so that fluid can fully flow through each position of each hole, and the short circuit of fluid flow is avoided or reduced. The two-phase fluid is separated into the liquid phase and the gas phase by the stabilizing device with the novel structure, the liquid phase is separated into small liquid masses, the gas phase is separated into small bubbles, the backflow of the liquid phase is inhibited, the gas phase is enabled to flow smoothly, the flow stabilizing effect is achieved, the vibration and noise reducing effect is achieved, and the heat exchange effect is improved. Compared with the stabilizing device in the prior art, the stabilizing device further improves the flow stabilizing effect, strengthens heat transfer and is simple to manufacture.

2) According to the invention, through reasonable layout, the square and regular octagonal through holes are uniformly distributed, so that the fluid on the whole cross street is uniformly divided, and the problem of nonuniform division of the annular structure along the circumferential direction in the prior art is avoided.

3) According to the invention, the square holes and the regular octagonal through holes are uniformly distributed at intervals, so that the large holes and the small holes are uniformly distributed on the whole cross section, and the separation effect is better through the position change of the large holes and the small holes of the adjacent stabilizing devices.

4) According to the invention, the stabilizing device is of a sheet structure, so that the stabilizing device is simple in structure and low in cost.

By arranging the annular stabilizing device, the invention equivalently increases the internal heat exchange area in the heat pipe, strengthens the heat exchange and improves the heat exchange effect.

The invention divides the gas phase and the liquid phase at all cross section positions of all heat exchange tubes, thereby realizing the contact area between the division of a gas-liquid interface and a gas phase boundary layer and a cooling wall surface on the whole heat exchange tube section and enhancing the disturbance, greatly reducing the noise and the vibration and strengthening the heat transfer.

Preferably, the stabilizing means comprises two types, as shown in figures 2 and 3, the first type being a square central stabilizing means, the square being located in the centre of the heat pipe or condenser tube, as shown in figure 3. The second is a regular octagonal central stabilizer, the regular octagon being located in the center of the heat pipe or condenser tube, as shown in fig. 2. As a preference, the two types of stabilizing means are arranged next to one another, i.e. the types of stabilizing means arranged next to one another differ. I.e. adjacent to the square central stabilizer is a regular octagonal central stabilizer, and adjacent to the regular octagonal central stabilizer is a square central stabilizer. According to the invention, the square holes and the regular octagon holes are uniformly distributed at intervals, so that the large holes and the small holes are uniformly distributed on the whole cross section, and through the position change of the large holes and the small holes of the adjacent stabilizing devices, the fluid passing through the large holes next passes through the small holes, and the fluid passing through the small holes next passes through the large holes to be further separated, so that the mixing of vapor and liquid is promoted, and the separating and heat exchanging effects are better.

Preferably, the heat pipe 11 has a square cross-section.

Through analysis and experiments, the distance between the stabilizing devices cannot be too large, the damping, noise reduction and separation effects are poor due to too large distance, the resistance is too large due to too small distance, and the side length of the square cannot be too large or too small, and the damping and noise reduction effects are poor or the resistance is too large, so that the damping and noise reduction can be optimized under the condition that the normal flow resistance (the total pressure bearing is less than 2.5MPa or the on-way resistance of a single heat pipe is less than or equal to 5Pa/M) is preferentially met through a large number of experiments, and the optimal relation of each parameter is arranged.

Preferably, the invention is arranged on a vertical flue. The heat pipe is vertical to the extending direction of the flue. I.e. the heat pipe extends in the horizontal direction.

Preferably, the distance between adjacent stabilizers is M1, the side length of the square through hole is C1, the heat pipe is a square section, and the side length of the square section of the heat pipe is C2, so that the following requirements are met:

M1/C2＝a*Ln(C1/C2)+b

wherein a, b are parameters, wherein 1.725< a <1.733,4.99< b < 5.01.

11<C2<46mm；

1.9<C1<3.2mm；

18<M1<27mm。

Further preferably, a is smaller and b is larger as C1/C2 is increased.

Preferably, a is 1.728, b is 4.997;

preferably, the side length C1 of the square through hole is the average of the inner side length and the outer side length of the square through hole, and the side length C2 of the square cross section of the heat pipe is the average of the inner side length and the outer side length of the heat pipe.

Preferably, the outer length of the square through hole is equal to the inner length of the square section of the heat pipe.

Preferably, as C2 increases, C1 also increases. However, as C2 increases, the increasing magnitude of C1 decreases. The change of the law is obtained through a large amount of numerical simulation and experiments, and the heat exchange effect and the noise are further improved through the change of the law.

Preferably, as C2 increases, M1 decreases. However, as C2 increases, the magnitude of M1 decreases progressively smaller. The change of the rule is obtained through a large amount of numerical simulation and experiments, and the heat exchange effect and the noise are further improved and reduced through the change of the rule.

Learn through analysis and experiment, the interval of heat pipe also satisfies certain requirement, for example can not too big or undersize, no matter too big or undersize can lead to the heat transfer effect not good, because set up stabilising arrangement in this application heat pipe moreover, consequently stabilising arrangement also has certain requirement to the heat pipe interval. Therefore, through a large number of experiments, under the condition that the normal flow resistance (the total pressure bearing is less than 2.5MPa, or the on-way resistance of a single heat pipe is less than or equal to 5Pa/M) is preferentially met, the damping and the noise reduction are optimized, and the optimal relation of each parameter is settled.

The distance between adjacent stabilizing devices is M1, the side length of a square is C1, the heat pipe is a square section, the side length of the heat pipe is C2, an acute angle formed by the heat pipe and a horizontal plane is A, and the distance between the centers of the adjacent heat pipes is M2, so that the following requirements are met:

M2/C2＝d*(M1/C2)²+e-f*(M1/C2)³-h*(M1/C2)；

wherein d, e, f, h are parameters,

1.239<d<1.240,1.544<e<1.545,0.37<f<0.38,0.991<h<0.992。

11<C2<46mm；

1.9<C1<3.2mm；

18<M1<27mm。

16<M2<76mm。

the spacing between the centers of adjacent heat pipes is M2, which refers to the distance between the centerlines of the heat pipes.

Further preferably, d is 1.2393, e is 1.5445, f is 0.3722, h is 0.9912;

preferably, d, e, f are larger and h is smaller as M1/C2 is increased.

Preferably, M2 increases with increasing C2, but the magnitude of the increase in M2 decreases with increasing C2. The change of the rule is obtained through a large amount of numerical simulation and experiments, and the heat exchange effect can be further improved through the change of the rule.

Preferably, the length of the evaporation end (the length of the heat pipe in the flue 1) is between 1000 and 1800 mm. More preferably, 1200-1400 mm.

Preferably, the length of the condensation end is between 500 and 900 mm. More preferably, 600-700 mm.

By optimizing the optimal geometric dimension of the formula, the optimal effects of shock absorption and noise reduction can be achieved under the condition of meeting the normal flow resistance.

For other parameters, such as pipe wall, wall thickness, etc., it is sufficient to set the parameters according to normal standards.

The heat pipes are multiple, and the distribution density of the heat pipes is smaller and smaller along the flowing direction of the flue gas. In numerical simulation and experiments, the heat pipes are heated less and less along the flowing direction of the flue gas, and the temperatures of the heat pipes at different positions are different, so that local heating is not uniform. Because the temperature of the flue gas is continuously reduced along with the continuous heat exchange of the flue gas, the heat exchange capacity is also reduced, and therefore, the density of the heat pipes arranged at different positions of the flue gas channel is different, the heat absorption capacity of the heat pipes is continuously reduced along the flow direction of the flue gas, the temperature of the whole heat pipes is kept basically the same, the whole heat exchange efficiency is improved, materials are saved, the local damage caused by uneven temperature is avoided, and the service life of the heat pipes is prolonged.

Preferably, the distribution density of the heat pipes is continuously increased with smaller and smaller amplitude along the flow direction of the flue gas. As the change of the distribution density of the heat pipes, the invention carries out a large number of numerical simulations and experiments, thereby obtaining the change rule of the distribution density of the heat pipes. Through the change rule, materials can be saved, and meanwhile, the heat exchange efficiency can be improved by about 9%.

Although the present invention has been described with reference to the preferred embodiments, it is not limited thereto. Various changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.