CN205279831U - Oval fin tubular heat exchanger and oval fin tubular intelligence phase transition heat transfer device - Google Patents

Abstract

The utility model provides an elliptical fin tube heat exchanger, which comprises a plurality of tube bundle upper connecting pipes, a plurality of tube bundle lower connecting pipes, a plurality of rows of finned tube bundles, a heat exchanger upper water collection pipe and a heat exchanger lower collection pipe. Water pipes; multiple rows of finned tube bundles are arranged in parallel with each other and with intervals, one end communicates with the upper connecting pipes of the multiple tube bundles in one-to-one correspondence, and the other end communicates with the lower connecting pipes of the multiple tube bundles in one-to-one correspondence; The connecting pipe is also connected with the upper water collecting pipe of the heat exchanger; the lower connecting pipe of the multiple tube bundles is also connected with the lower water collecting pipe of the heat exchanger; the inlet of the upper water collecting pipe of the heat exchanger is connected with the pipeline for inputting liquid refrigerant, The outlet of the water collecting pipe communicates with the pipeline for outputting the liquid cold working medium; wherein, the section of the plurality of finned tubes contained in each row of finned tube bundles is elliptical. The utility model also provides an elliptical fin tube type intelligent phase-change heat device. The utility model reduces the dust accumulation of the finned tubes, improves the heat exchange effect and improves the heat exchange efficiency.

Description

Elliptical fin tube heat exchanger and elliptical fin tube intelligent phase change heat device

technical field

The utility model belongs to the technical field of energy saving, in particular to an elliptical fin tube heat exchanger and an elliptical fin tube intelligent phase-change heat device.

Background technique

In the flue at the tail of the boiler, there is generally a finned tube heat exchanger for absorbing the waste heat of the flue gas. Due to the high viscosity of impurities produced after fuel combustion, and the finned tube of the finned tube heat exchanger in the prior art is a circular finned tube, its cross section is circular, so when the flue gas flows through the finned tube heat exchanger After the heat exchanger, it is easy to accumulate dust in the triangular rear part of the circular finned tube, thus affecting the heat transfer efficiency of the finned tube.

Contents of the invention

In order to solve the above problems, the utility model provides an elliptical finned tube heat exchanger on the one hand, which includes: a plurality of tube bundles upper connecting pipes, a plurality of tube bundles lower connecting pipes, a plurality of rows of finned tube bundles, a heat exchanger upper set The water pipe and the lower water collecting pipe of the heat exchanger; multiple rows of the finned tube bundles are arranged in parallel with each other and with intervals, one end communicates with the plurality of the upper connecting pipes of the tube bundle one by one, and the other end communicates with the plurality of the finned tube bundles. The lower connecting pipes of the tube bundle are connected in one-to-one correspondence; the plurality of upper connecting pipes of the tube bundle are also connected with the upper water collection pipe of the heat exchanger; the plurality of lower connecting pipes of the tube bundle are also connected with the lower water collection pipe of the heat exchanger; The inlet of the upper water collection pipe of the heat exchanger is connected with the pipeline for inputting the liquid refrigerant, and the outlet of the lower water collection pipe of the heat exchanger is connected with the pipe for outputting the liquid refrigerant; wherein, each row of the finned tube bundles Contains a plurality of finned tubes in a row parallel to each other with intervals, one end of the plurality of finned tubes is used as one end of each row of finned tube bundles, and the other end of the plurality of finned tubes One end serves as the other end of each row of the finned tube bundles, and the section of the finned tubes is oval.

In the above-mentioned elliptical fin tube heat exchanger, preferably, the multiple rows of finned tube bundles are divided into odd-numbered finned tube bundles and even-numbered finned tube bundles; each row of finned tube bundles in the odd-numbered finned tube bundles The finned tube bundles and each row of finned tube bundles in the even-numbered rows of finned tube bundles are arranged in a staggered arrangement.

In the above-mentioned elliptical fin-tube heat exchanger, preferably, the ratio of the semi-major axis to the semi-minor axis of the ellipse is greater than or equal to 1.4.

In the above-mentioned elliptical fin-tube heat exchanger, preferably, the liquid refrigerant is water.

Another aspect of the utility model provides an elliptical fin tube type intelligent phase-change heat device, which includes: a heat absorption section, an ascending pipe, a heat releasing section, a descending pipe and a flow regulator; the heat absorption section is installed on In the flue at the tail of the boiler, the liquid cold working fluid in the heat-absorbing section absorbs the heat of the flue gas entering the heat-absorbing section and becomes a gaseous working fluid; The outlet on the mass side and the inlet on the side of the heat release section transport the gaseous thermal working fluid in the heat absorption section to the heat release section; the heat release section is installed outside the flue, and the heat release section The gaseous thermal working medium in the hot section exchanges heat with the cold source entering the exothermic section and becomes a liquid cold working medium, and the cold source in the exothermic section and the gaseous thermal working medium in the exothermic section After heat exchange, it becomes a heat source, wherein the cold source includes air; the downcomer connects the working fluid side outlet of the heat release section and the working medium side inlet of the heat absorption section, and transfers the The liquid refrigerant is delivered to the heat absorption section; the flow regulator is installed on the downcomer to adjust the water intake of the liquid refrigerant in the downcomer into the heat absorption section, thereby controlling the The wall temperature of the heating surface of the heating section is above the dew point temperature of boiler fuel acid; wherein, the heat absorbing section is the above-mentioned elliptical finned tube heat exchanger, and multiple rows of finned tube bundles are arranged in sequence along the flow direction of the flue gas.

In the above-mentioned elliptical fin tube type intelligent phase-change heat device, preferably, the liquid cold working medium is water, and the gaseous hot working medium is steam.

In the above-mentioned elliptical fin tube type intelligent phase-change heat device, preferably, the cold source is air.

In the above-mentioned elliptical fin tube type intelligent phase-change heat device, preferably, the flow regulator includes a first regulating valve and a wall surface temperature tester; the first regulating valve is installed on the downcomer, The wall temperature tester is used to measure the wall temperature of the heated surface of the heat absorbing section.

In the above-mentioned elliptical fin tube type intelligent phase-change heat device, preferably, the flow regulator further includes: a controller; the controller is connected with the first regulating valve and the wall surface temperature tester , controlling the first regulating valve according to the preset gas acid dew point temperature and the wall temperature of the heated surface measured by the wall temperature tester.

In the above-mentioned elliptical fin tube type intelligent phase heat exchange device, preferably, the flue at the tail of the boiler is the flue at the tail of the boiler.

The beneficial effects brought by the technical solution provided by the embodiment of the utility model are:

By setting the cross section of the finned tubes into an ellipse, the dust accumulation of the finned tubes is reduced, and the heat exchange effect is improved at the same time, and the heat exchange efficiency is increased.

Description of drawings

Fig. 1 is a top view structural schematic diagram of an elliptical finned tube heat exchanger provided by an embodiment of the present invention;

Fig. 2 is a schematic view of the structure of an elliptical finned tube heat exchanger provided by the embodiment of the present invention;

Fig. 3 is a schematic diagram of the connection between a row of finned tube bundles, an upper connecting pipe of a tube bundle and a lower connecting pipe of a tube bundle provided by the embodiment of the present invention;

Fig. 4 is a schematic structural diagram of an elliptical finned tube type intelligent phase-change heat device provided by an embodiment of the utility model;

Among them, the symbols in the figure are explained as follows:

1 tube bundle upper connecting tube, 2 tube bundle lower connecting tube, 3 finned tube bundle, 31 odd-numbered finned tube bundle, 32 even-numbered finned tube bundle, 33 finned tubes, 4 heat exchanger upper water collection pipe, 5 heat exchanger lower collection Water pipes, 6 heat-absorbing sections, 7 ascending pipes, 8 heat-releasing sections, 9 descending pipes, 100 regulating valves, 101 wall surface temperature testers, 102 controllers.

detailed description

In order to make the purpose, technical solutions and advantages of the present utility model clearer, the implementation of the present utility model will be further described in detail below in conjunction with the accompanying drawings.

Referring to Figures 1 to 3, an embodiment of the utility model provides an elliptical finned tube heat exchanger, which includes: a plurality of tube bundles upper communicating tubes 1, a plurality of tube bundles lower communicating tubes 2, and multiple rows of finned tube bundles 3 , the upper water collecting pipe 4 of the heat exchanger and the lower water collecting pipe 5 of the heat exchanger. The elliptical finned tube heat exchanger is set in the flue at the tail of the boiler.

Among them, multiple rows of finned tube bundles 3 are arranged in parallel with each other and with intervals. One end of each row of finned tube bundles 3 communicates with the upper connecting pipes of multiple tube bundles one by one, and the other end of each row of finned tube bundles 3 is connected to The connecting tubes under the multiple tube bundles are connected in one-to-one correspondence. Each row of finned tube bundles 3 contains a plurality of finned tubes 33, and each finned tube 33 includes a tube body and fins formed on the outer wall of the tube, as shown in Fig. Arranging in sequence with intervals to form a row of finned tube bundles 3, one end of multiple finned tubes 33 is used as one end of each row of finned tube bundles 3, and the other end of multiple finned tubes 33 is used as each row of finned tube bundles 3 the other end of the The section of the finned tube 33 is elliptical, that is, the finned tube is an elliptical finned tube, and the tube body of the finned tube is an elliptical tube body. The upper connecting pipes 1 of the plurality of tube bundles are also connected with the upper water collecting pipe 4 of the heat exchanger, and the lower connecting pipes 2 of the plurality of tube bundles are also connected with the lower water collecting pipe 5 of the heat exchanger. The inlet of the upper water collection pipe 4 of the heat exchanger communicates with the pipeline for inputting the liquid refrigerant, and the outlet of the lower water collector 5 of the heat exchanger communicates with the pipeline for outputting the liquid refrigerant. The liquid refrigerant is water. In order to resist the dew point corrosion of sulfur-containing flue gas, the material of the finned tube is 09CrCuSb steel. The finned tubes are preferably high frequency resistance welded spiral finned tubes. Because the eddy current in the separation area of the elliptical finned tube is reduced, the ash in the leeward area is reduced. In the case of high ash, the leeward area of the circular finned tube is seriously ash, and even the generated ash cone forms a bridge, and the elliptical finned tube is not easy to form a bridge formed by the ash cone, so that the ash accumulation of the elliptical finned tube is reduced.

At the same time, the elliptical finned tube has the following obvious advantages compared with the circular finned tube: 1) The heat exchange effect is improved. For the same perimeter, since the flow cross-sectional area of the elliptical finned tube is smaller than that of the circular finned tube, if the flow rate remains constant, the disturbance will be strengthened, and the convective heat transfer in the tube will be enhanced. For the situation outside the tube, from the perspective of the position of the fluid separation point and the development of the boundary layer, the average heat transfer effect outside the elliptical finned tube is always better than that of the circular finned tube. Since the ellipse is similar to the streamline shape, the resistance of the fluid is lower when the fluid is swept outward. Small, the flow rate can be increased while allowing the same flow resistance, so the external heat transfer can also be enhanced. 2) The external flow characteristics of the oval tube are good. When the fluid sweeps along the long axis of the ellipse, the separation point of the elliptical finned tube moves backward, and the flow loss caused by the Karman vortex street in the separation area will undoubtedly be greatly reduced. 3) The heat exchanger has a compact structure, that is, under the same flow area, the heat transfer circumference of the elliptical finned tube is longer, and the heat transfer area is correspondingly increased. The structure also allows a more compact arrangement, which increases the heat transfer per unit volume. Based on this, the heat transfer coefficient of elliptical finned tubes is 15% higher than that of circular finned tubes, while its resistance is 18% lower than that of circular finned tubes. Compared with the elliptical finned tube heat exchanger formed by round finned tubes, the elliptical tube heat exchanger (that is, the elliptical finned tube heat exchanger formed by elliptical finned tubes) has a specific heat transfer capacity. The required heat exchange area is smaller and the power consumption is also smaller.

In order to further reduce the amount of dust accumulation of the elliptical finned tube, the ratio of the major semi-axis to the minor semi-axis of the ellipse is greater than or equal to 1.4. After use, when it is greater than or equal to 1.4, the leeward side of the oval tube will basically not produce ash cones.

Referring to Figures 1 and 2, in order to increase the effective contact area with the flue gas, the multi-row finned tube bundles are divided into odd-numbered finned tube bundles 31 and even-numbered finned tube bundles 32, along the flow direction of the flue gas, each row of finned tube bundles is The tube bundles are numbered with natural numbers. Starting from 1, all finned tube bundle rows numbered 1, 3, ..., (2n+1) are called odd-numbered finned tube bundles. Starting from 2, they are numbered 2, 4, ..., All finned tube bundles of (2n+2) form odd-numbered finned tube bundles called even-numbered finned tube bundles, where n is a positive integer. Each row of finned tube bundles in odd-numbered rows of finned tube bundles 31 and each row of finned tube bundles in even-numbered rows of finned tube bundles 32 are staggered.

The upper connecting pipes 1 of the plurality of tube bundles are divided into the first upper connecting group and the second upper connecting group. The upper connecting pipe 1 of each tube bundle in the group is welded to the upper water collecting pipe 4 of the heat exchanger. The lower connecting pipes 2 of the plurality of tube bundles are divided into a first lower connecting group and a second lower connecting group, each lower connecting pipe 2 of the first lower connecting group is flange-connected with the lower water collecting pipe 5 of the heat exchanger, and the second lower connecting The lower connecting pipe 2 of each tube bundle in the group is welded to the lower water collecting pipe 5 of the heat exchanger. Multiple rows of finned tube bundles 3 are arranged in parallel with each other and spaced apart. The multiple rows of finned tube bundles 3 are divided into a first fin group and a second fin group along the arrangement direction, and each group includes at least one row of finned tube bundles. , one end of each row of fin tube bundles in the first fin group communicates with the first upper connecting group, the other end of each row of fin tube bundles in the first fin group communicates with the first lower connecting group, and the second fin group’s One end of each row of fin tube bundles communicates with the second upper communication group, and the other end of each row of fin tube bundles in the second fin group communicates with the second lower communication group. Each row of finned tube bundles 3 contains a plurality of finned tubes 33, and the plurality of finned tubes 33 are arranged successively in parallel with each other and with intervals between each other. One end and the other end of the plurality of finned tubes 33 serve as the other end of each row of finned tube bundles.

When the finned tube bundle heat exchanger is used, the position of the first fin group is forward, and it is easy to cause the wear or leakage of the tube wall before the second fin group, which will lead to the heat exchange failure of the finned tube bundle heat exchanger and the smoke exhaust. The temperature rises, resulting in waste of energy. Therefore, by connecting the first upper communication group and the first lower communication group connected with the first fin group to the flanges of the upper water collection pipe 4 of the heat exchanger and the lower water collection pipe 5 of the heat exchanger To connect, weld the second upper connecting group connected with the second fin group to the upper header 4 of the heat exchanger, and weld the second lower connecting group connected to the second fin group to the lower header 4 of the heat exchanger connection, so that the heat exchange unit composed of the first fin group, the first upper communication group and the first lower communication group is connected to the upper water collection pipe 4 of the heat exchanger and the lower water collection pipe 5 of the heat exchanger in a detachable connection mode , compared to an integral heat exchange unit formed by welding multiple rows of finned tube bundles, multiple tube bundle upper connecting pipes and multiple tube bundle lower connecting pipes, when the tube wall wears or leaks, the replacement is quick and convenient, saving maintenance costs, And avoid energy waste. In application, the tube walls in the first three rows of finned tube bundles are prone to wear or leakage, so the first upper connecting group contains three upper connecting tubes 1 of the tube bundle, the first lower connecting group contains three lower connecting tubes 2 of the tube bundle, and the first The fin group contains three rows of finned tube bundles 3, and each row of finned tube bundles 3 communicates with an upper connecting pipe 1 of the tube bundle and a lower connecting pipe 2 of the tube bundle. Referring to Fig. 4, another embodiment of the utility model also provides an elliptical fin tube type intelligent phase-change heat device, which includes: a heat-absorbing section 6, an ascending pipe 7, a heat-releasing section 8, a descending pipe 9 and a flow rate Regulator.

Among them, the heat-absorbing section 6 (or called the lower section of the phase-change heat exchanger) is installed in the flue at the tail of the boiler, and is used to absorb the heat of the flue gas flowing through the heat-absorbing section 6 to heat the liquid refrigerant therein. The cold working fluid absorbs heat and becomes a gaseous hot working fluid. The flue gas enters from the flue gas side inlet of the heat absorbing section 6, and after releasing heat in the heat absorbing section 6, it is discharged from the flue gas side outlet; the liquid cold working fluid enters from the working fluid side inlet of the heat absorbing section 6, and After absorbing heat in the section 6, it is discharged from the outlet of the working fluid side of the endothermic section 6, and the endothermic process is completed. Due to the large specific heat capacity of water and in order to reduce costs, the liquid cold working medium is preferably water, and the corresponding gaseous hot working medium is steam. The flue at the tail of the boiler can be the flue at the tail of the atmospheric reduction furnace. The heat-absorbing section is the aforementioned elliptical finned tube heat exchanger, which includes: multiple tube bundle upper connecting pipes 1, multiple tube bundle lower connecting pipes 2, multiple rows of finned tube bundles 3, heat exchanger upper water collection pipe 4 and heat exchanger The lower water collecting pipe 5 of the heater; multiple rows of finned tube bundles 3 are arranged sequentially along the flow direction of the flue gas, and the cross-section of each finned tube of each row of finned tube bundles is elliptical. .

The riser pipe 7 communicates with the outlet of the working fluid side of the heat absorption section 6 and the inlet of the working fluid side of the heat release section 8 , and transports the gaseous thermal working medium in the heat absorption section 6 to the heat release section 8 . The heat energy generated during the process of changing the liquid cold working medium into the gaseous hot working medium can make the gaseous hot working medium enter the heat release section 8 through the riser 7 without external driving force, which improves the energy utilization rate.

The exothermic section 8 (or called the upper section of the phase change heat exchanger) is installed outside the flue, and is used to release the heat of the gaseous thermal working medium entering the exothermic section 8 to heat the cold source entering it. After heating, it becomes a liquid cold working medium, and the cold source and the gaseous heat working medium exchange heat and become a heat source, wherein the cold source is air, and correspondingly, the heat source is also air, and the temperature of the heat source is higher than that of the cold source. The gaseous hot working fluid enters from the working medium side inlet of the heat release section 8, and after releasing heat in the heat release section 8, it becomes a liquid cold working medium, and then is discharged from the working medium side outlet; the cold source comes from the air in the heat release section 8 The side inlet enters, and after absorbing heat in the heat release section 8, it becomes a heat source, and then is discharged from the air side outlet of the heat release section 8, that is, the heat release process is completed. After the heat source is discharged, it can enter the air preheater for reheating. The air preheater is installed in the boiler, and its installation position is upstream of the flue gas relative to the installation position of the heat absorption section 6 .

One end of the downcomer 9 communicates with the working fluid side outlet of the heat release section 8, and the other end of the downcomer 9 communicates with the working medium side inlet of the heat absorption section 6, and the liquid cold working fluid in the heat release section 8 is transported to the heat absorption section 8. paragraph 6. After the gaseous heat working medium is changed into liquid cold working medium, relying on the gravity of the liquid cold working medium, it enters the heat-absorbing section 6 through the downcomer 9 without external driving force, which improves the energy utilization rate. In other words, the endothermic and exothermic processes do not require external driving force, relying on the generated heat energy and their own gravity to form a natural cycle.

The flow regulator is installed on the downcomer 9, and is used to adjust the water intake of the liquid refrigerant in the downcomer 9 into the heat-absorbing section 6, so as to increase or decrease the circulation amount of the liquid refrigerant, and then adjust the flow rate of the liquid refrigerant. The amount of heat exchange between the substance and the flue gas in the heat-absorbing section 6, thereby controlling the wall temperature of the heating surface of the heat-absorbing section 6, so that the temperature of the wall surface of the heating surface is above the dew point temperature of the fuel acid, for example, controlling the temperature ratio of the wall surface temperature of the heating surface to the dew point of the fuel acid temperature is 10° higher. Through the control of the flow regulator, the cooling rate of the exothermic section 8 can be balanced with the heat absorption rate of the endothermic section 6, the natural circulation of saturated steam and saturated water can be balanced, and the wall temperature (or wall temperature) of the heating surface remains constant. .

The flow regulator includes a regulating valve 100 and a wall temperature tester 101 . The regulating valve 100 is installed on the downcomer 9 and is used for regulating the water intake of the liquid refrigerant in the downcomer 9 into the heat absorption section 6 . The wall surface temperature tester 101 is used to measure the wall surface temperature of the heating surface of the heat absorbing section 6. During application, it can be installed on the heating surface of the heat absorbing section 6 to directly measure the wall surface temperature of the heating surface; in order to realize simple measurement, it can be installed on the rising On the tube 7, the temperature of the wall surface of the heating surface is measured indirectly, and the temperature of the wall surface of the heating surface is measured by measuring the temperature of the steam.

In order to realize automation, the flow regulator also includes: a controller 102, which is connected with the regulating valve 100 and the wall surface temperature tester 101, and is adjusted according to the preset gas acid dew point temperature and the wall temperature of the heated surface measured by the wall surface temperature tester 101. The valve 100 is controlled to increase or decrease the circulating volume of the liquid refrigerant, and then adjust the heat transfer in the heat absorption section 6 , thereby increasing or decreasing the temperature of the heating surface wall of the heat absorption section 6 . Specifically, the preset value of the wall temperature of the heated surface is set to be higher than the gas acid dew point temperature value, for example, 10° higher, and the wall temperature of the heated surface measured by the wall temperature tester 101 is compared with the preset value, and if it is higher than the preset value value, then increase the opening degree of the regulating valve 100, if it is less than the preset value, then reduce the opening degree of the regulating valve 100, so that the temperature of the wall surface of the heating surface is stabilized at the preset value, and the temperature of the wall surface of the heating surface (or wall temperature ) remains constant.

In order to further reduce the exhaust gas temperature of the furnace and maximize the energy-saving benefits, the cold source also includes: desalinated water, and the elliptical fin tube type intelligent phase-change heat device also includes a desalinated water heat exchange section; the gaseous thermal process in the absorption section 6 After flowing through the heat release section 8, it enters the desalted water heat exchange section to exchange heat with the desalted water entering the desalted water heat exchange section, and the liquid refrigerant flows into the downcomer 9 after the heat exchange, so that the flue gas can be further improved. The efficiency of waste heat recovery and the safe and economical operation of the heating surface of the heat absorbing section. The liquid cold working medium in the desalted water heat exchange section can enter the heat releasing section 8 from the liquid working medium side inlet of the heat releasing section 8 through the pipeline, and be discharged from the liquid working medium side outlet in the heat releasing section 8 to the downcomer 4 Inside. The desalinated water heat exchange section is preferably a U-shaped tube heat exchanger. A regulating valve is installed on the desalted water delivery pipeline connected with the desalted water heat exchange section's desalted water inlet, which is used to adjust the flow of desalted water, and then adjust the heat transfer in the desalted water heat exchange section, thereby facilitating the control of the heating surface The wall temperature remains constant. The regulating valve is connected with the controller 8, which is easy to realize the automation of control.

In summary, the beneficial effects of the embodiments provided by the utility model are as follows:

By setting the cross-section of the finned tube bundle into an ellipse, the dust accumulation of the elliptical finned tubes is reduced, and the heat exchange effect is improved at the same time, and the heat exchange efficiency is increased.

It can be known from technical knowledge that the utility model can be realized through other implementations without departing from its spirit or essential features. Accordingly, the above-disclosed embodiments are, in all respects, illustrative and not exclusive. All changes within the scope of the utility model or within the range equivalent to the utility model are included in the utility model.

Claims (9)

1. An elliptical finned tube heat exchanger, characterized in that the elliptical finned tube heat exchanger comprises: a plurality of tube bundles upper connecting tubes, a plurality of tube bundles lower connecting tubes, a plurality of rows of finned tube bundles, a heat exchanger Heater upper header and heat exchanger lower header; The plurality of rows of finned tube bundles are arranged in parallel with each other and with intervals, one end communicates with the plurality of upper connecting pipes of the tube bundle in one-to-one correspondence, and the other end communicates with the plurality of lower communicating pipes of the tube bundle in one-to-one correspondence; The plurality of upper connecting pipes of the tube bundle are also in communication with the upper water collection pipe of the heat exchanger; A plurality of connecting pipes under the tube bundle are also in communication with the lower water collection pipe of the heat exchanger; The inlet of the upper water collection pipe of the heat exchanger communicates with the pipeline for inputting the liquid refrigerant, and the outlet of the lower water collection pipe of the heat exchanger communicates with the pipeline for outputting the liquid refrigerant; Wherein, each row of the finned tube bundles contains a plurality of finned tubes forming a row parallel to each other with intervals, and one end of the plurality of finned tubes is used as one end of each row of the finned tube bundles, The other end of the plurality of finned tubes is used as the other end of each row of the finned tube bundle, and the section of the finned tubes is oval. 2. The elliptical finned tube heat exchanger according to claim 1, wherein the multi-row finned tube bundles are divided into odd-numbered finned tube bundles and even-numbered finned tube bundles; Each row of finned tube bundles in the odd-numbered rows of finned tube bundles and each row of finned tube bundles in the even-numbered rows of finned tube bundles are arranged in a staggered arrangement. 3. The elliptical fin-tube heat exchanger according to claim 1, wherein the ratio of the semi-major axis to the semi-minor axis of the ellipse is greater than or equal to 1.4. 4. The elliptical finned tube heat exchanger according to claim 1, wherein the liquid refrigerant is water. 5. An elliptical finned tube type intelligent phase-change heat device, characterized in that the elliptical finned tube type intelligent phase-change heat device comprises: a heat absorbing section, an ascending pipe, a heat releasing section, a descending pipe and a flow rate Regulator; The heat-absorbing section is installed in the flue at the tail of the boiler, and the liquid refrigerant in the heat-absorbing section absorbs the heat of the flue gas entering the heat-absorbing section and becomes a gaseous refrigerant; The riser connects the working medium side outlet of the heat absorbing section with the working medium side inlet of the heat releasing section, and transports the gaseous thermal working medium in the heat absorbing section to the heat releasing section; The exothermic section is installed outside the flue, and the gaseous thermal working medium in the exothermic section becomes a liquid refrigerant after exchanging heat with the cold source entering the exothermic section. The cold source becomes a heat source after exchanging heat with the gaseous thermal working medium in the heat release section, wherein the cold source includes air; The downcomer communicates with the working fluid side outlet of the heat releasing section and the working medium side inlet of the heat absorbing section, and transports the liquid cold working fluid in the heat releasing section to the heat absorbing section; The flow regulator is installed on the downcomer to adjust the water intake of the liquid refrigerant in the downcomer entering the heat-absorbing section, thereby controlling the temperature of the heated surface of the heat-absorbing section to be within the boiler fuel acid dew point above the temperature; Wherein, the heat absorbing section is the elliptical finned tube heat exchanger according to any one of claims 1 to 3, and multiple rows of the finned tube bundles are arranged sequentially along the flow direction of the flue gas. 6 . The elliptical fin tube type intelligent phase-change heat device according to claim 5 , wherein the liquid cold working medium is water, and the gaseous hot working medium is steam. 7 . 7. The elliptical fin tube type intelligent phase-change heat device according to claim 5, wherein the cooling source is air. 8. The elliptical fin tube type intelligent phase-change heat device according to claim 5, wherein the flow regulator comprises a first regulating valve and a wall surface temperature tester; The first regulating valve is installed on the downcomer, and the wall temperature tester is used to measure the wall temperature of the heated surface of the heat absorbing section. 9. The elliptical fin tube type intelligent phase-change heat device according to claim 8, characterized in that, the flow regulator further comprises: a controller; The controller is connected to the first regulating valve and the wall temperature tester, and the first regulating valve is tested according to the preset gas acid dew point temperature and the wall temperature of the heated surface measured by the wall temperature tester. control.