Elliptical tube type economizer

Abstract

The invention provides an oval tube type economizer. The oval tube type economizer comprises a support, a heat exchange tube, a U-shaped connecting tube, a water inlet and a water outlet. The supports are fixed to the two sides, and the heat exchange tubes are horizontally connected between the supports to form a multi-layer and multi-column matrix. The ends of the heat exchange pipes are connected through U-shaped connecting pipes to form medium channels, the top ends of the medium channels are connected with a water inlet, and the bottom ends of the medium channels are connected with a water outlet. The section of the heat exchange tube is oval, and heat exchange fins are fixedly arranged on the outer wall of the heat exchange tube and are arranged in an inclined mode. The heat exchange tube adopts the elliptical cross section to increase the heat transfer area, and the heat exchange fins are inclined to guide flue gas to flow around and be mixed.

Description

Technical Field

[0001] This invention relates to the field of boiler equipment, and more specifically to an elliptical tube economizer. Background Technology

[0002] The economizer is a key energy-saving device in a coal-fired boiler system. It is typically installed in the flue gas duct at the boiler's tail end, using waste heat from the flue gas to preheat the boiler feedwater, thereby reducing the exhaust gas temperature and improving boiler thermal efficiency. Its core principle is that water within heat exchange tubes absorbs heat from the high-temperature flue gas, reducing fuel consumption.

[0003] In recent years, with the gradual implementation of carbon peaking policies, the country has made green emission reduction an important task, requiring the elimination of outdated boilers with a capacity of less than 100,000 tons of steam per hour by 2025, and requiring all newly built boilers to be equipped with high-efficiency economizers to improve thermal efficiency.

[0004] The main feasible technical means to improve economizer efficiency is to increase the heat transfer area. However, the diameter of the heat exchange tubes is related to the working fluid flow rate and cannot be changed arbitrarily. Existing technologies also add heat exchange fins to the surface of the heat exchange tubes, but the direction of the fins is arranged along the flue gas flow direction and does not change the flow direction of the flue gas. As the economizer absorbs heat from the flue gas, the temperature of the flue gas is not uniform, causing localized low-temperature flue gas to have difficulty continuing to exchange heat with the economizer, thus reducing heat exchange efficiency.

[0005] It is not difficult to see that existing technologies still have certain shortcomings. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide an elliptical tube economizer, wherein the heat exchange tube adopts an elliptical cross section to increase the heat transfer area, and the heat exchange fins are inclined to guide the flue gas to flow around and mix.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] An elliptical tube economizer includes a support frame, heat exchange tubes, U-shaped connecting pipes, an inlet, and an outlet. The support frame is fixed on both sides, and several heat exchange tubes are horizontally connected between the support frame to form a multi-layer, multi-column matrix. The heat exchange tubes are connected at their ends by U-shaped connecting pipes to form a medium channel. The top end of the medium channel is connected to the inlet, and the bottom end of the medium channel is connected to the outlet. The heat exchange tubes have an elliptical cross-section, and heat exchange fins are fixedly provided on the outer wall of the heat exchange tubes. The heat exchange fins are inclined.

[0009] Furthermore, the heat exchange fins on adjacent heat exchange tubes are tilted in opposite directions.

[0010] Furthermore, the major axis of the elliptical heat exchange tube is inclined and forms an angle with the flue gas flow direction.

[0011] Furthermore, the major axes of the ellipses of adjacent heat exchange tubes are tilted in opposite directions.

[0012] Furthermore, the heat exchange fins on the upper heat exchange tubes are arranged less densely than those on the lower heat exchange tubes.

[0013] Furthermore, several layers of heat exchange tubes constitute a heat exchange unit, and a flue gas guiding zone is provided between adjacent heat exchange units. A guide plate connected to one side of the support is fixed in the flue gas guiding zone, and adjacent guide plates are connected to supports on different sides to form an S-shaped flue gas channel.

[0014] Furthermore, the heat exchange tube is equipped with a turbulence generator inside.

[0015] Furthermore, the surface of the heat exchange tube and heat exchange fins is provided with a hydrophobic and anti-corrosion coating.

[0016] The elliptical tube economizer provided by this invention has the following advantages:

[0017] The heat exchange tube has an elliptical cross-section, which increases the heat transfer area without increasing the working fluid flow rate. The inclined heat exchange fins have a turbulence effect, which allows the flue gas to be continuously turbulent and mixed. This avoids the generation of local low temperatures through thermal convection and improves the efficiency of the economizer.

[0018] The elliptical major axis of the heat exchange tube is inclined, which also has a certain turbulence effect;

[0019] Turbulent flue gas can assist in soot blowing and prevent soot accumulation from affecting heat exchange efficiency;

[0020] It is equipped with a flue gas guide zone and a guide plate to further increase the turbulence effect of the flue gas;

[0021] It has a hydrophobic and anti-corrosion coating to prevent flue gas from corroding the surface of heat exchange tubes and heat exchange fins, and also to prevent water vapor condensation. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the overall structure of an elliptical tube economizer provided by the present invention.

[0024] Figure 2 This is a schematic diagram of the side layout of the heat exchange tubes.

[0025] Figure 3This is a schematic diagram of the layout of the turbulence generators inside the heat exchange tube.

[0026] Explanation of reference numerals in the attached figures:

[0027] 1. Support bracket 2. Heat exchange tube

[0028] 3. U-shaped connecting pipe; 4. Water inlet

[0029] 5. Water outlet 6. Heat exchange fins

[0030] 7. Deflector plate 8. Bumper Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments and accompanying drawings. It should be noted that the described embodiments are merely some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0032] Example 1

[0033] Please see Figures 1 to 2 This invention provides an elliptical tube economizer, including a support 1, heat exchange tubes 2, U-shaped connecting pipes 3, a water inlet 4, and a water outlet 5. The support 1 is fixed on both sides, and several heat exchange tubes 2 are horizontally connected between the support 1 to form a multi-layer, multi-column matrix. The heat exchange tubes 2 are connected at their ends by U-shaped connecting pipes 3 to form a medium channel. The top end of the medium channel is connected to the water inlet 4, and the bottom end of the medium channel is connected to the water outlet 5. The heat exchange tubes 2 have an elliptical cross-section, and heat exchange fins 6 are fixedly provided on the outer wall of the heat exchange tubes 2. The heat exchange fins 6 are inclined.

[0034] The heat exchange tube 2 has an elliptical cross-section, which can increase the heat exchange area without increasing the flow rate. The ratio of the major axis to the minor axis of the ellipse is preferably 1.5-2.0. The inclined heat exchange fins 6 can drive the flue gas to turbulence, so that the flue gas mixes as much as possible for heat convection and prevents the formation of local low temperature regions.

[0035] As a further preferred option, the heat exchange fins 6 on adjacent heat exchange tubes 2 are tilted in opposite directions. As the flue gas flows from top to bottom, it passes through multiple layers of heat exchange tubes 2 in sequence, and under the guiding effect of the heat exchange fins 6, it will undergo multiple reverse turbulence.

[0036] As a further preferred embodiment, the major axis of the ellipse of the heat exchange tube 2 is inclined, forming an angle with the flue gas flow direction. The major axes of the ellipses of adjacent heat exchange tubes 2 are inclined in opposite directions. The angle between the heat exchange tube 2 and the flue gas direction is preferably between 30° and 45°.

[0037] Since the elliptical flat tube structure of heat exchange tube 2 also has a certain flow guiding effect, it can increase the turbulence of flue gas in another dimension. It is equivalent to the flue gas flowing from the Z-axis, and under the action of heat exchange fins 6 and heat exchange tube 2 itself, it will make turbulence motions in the X-axis and Y-axis respectively.

[0038] Preferably, the heat exchange fins 6 on the upper heat exchange tube 2 are arranged more sparsely than the heat exchange fins 6 on the lower heat exchange tube 2.

[0039] The economizer of this invention differs from traditional economizers that transport the medium from bottom to top; instead, it employs a top-to-bottom transport method. This is because flue gas flows from top to bottom, and continuous heat release along its flow direction enhances heat exchange. The upper layer of flue gas has a higher temperature, which gradually decreases after passing through the economizer layer by layer. Therefore, transporting the medium from top to bottom results in a larger temperature difference between the medium and the flue gas at the upper heat exchange tube 2, leading to higher heat exchange efficiency. To optimize heat exchange efficiency, the heat exchange fins 6 on the upper heat exchange tube 2 are arranged more sparsely, yet the efficiency is still sufficient. The lower heat exchange fins 6 are arranged more densely, maximizing heat absorption even with a smaller temperature difference, continuously absorbing heat from the flue gas, resulting in better overall heat absorption efficiency.

[0040] Further optimization can be achieved by having several layers of heat exchange tubes 2 form a heat exchange unit. A flue gas guide zone is provided between adjacent heat exchange units. A guide plate 7 connected to one side of the support 1 is fixed in the flue gas guide zone. Adjacent guide plates 7 are connected to the supports 1 on different sides to form an S-shaped flue gas channel.

[0041] Taking the attached diagram as an example, every two layers of heat exchange tubes 2 constitute a heat exchange unit. After passing through each heat exchange unit, the temperature of the flue gas decreases by one stage. Preferably, the flow is adjusted to fully agitate and homogenize the temperature before it is sent to the next heat exchange unit for heat exchange. Thus, the economizer forms a multi-stage structure, with each heat exchange unit essentially acting as a subdivided small economizer, and these stages are connected in series.

[0042] like Figure 3 As shown, preferably, the heat exchange tube 2 is equipped with a flow disruptor 8 inside. Sufficient flow disruption on the medium side also helps to improve heat absorption efficiency. Therefore, the flow disruptor 8 is used to increase the flow of the medium. The specific structure of the flow disruptor 8 is not limited; common types include spiral mixers and multi-bladed types.

[0043] Preferably, the surfaces of the heat exchange tube 2 and the heat exchange fins 6 are provided with a hydrophobic and anti-corrosion coating. High-temperature flue gas contains not only water vapor and soot, but also certain sulfides, which can corrode the metal surfaces of the heat exchange tube 2 and the heat exchange fins 6. The hydrophobic and anti-corrosion coating can prevent water vapor condensation and also prevent corrosive substances from directly contacting the metal surface, thereby improving the service life of the equipment.

[0044] This invention provides an elliptical tube economizer, which improves the heat exchange tube 2 to an elliptical cross-section, increasing the heat exchange area. Simultaneously, by tilting the heat exchange tube 2 and the heat exchange fins 6, the flue gas is turbulent, preventing the formation of a low-temperature zone that reduces heat exchange efficiency. The rational arrangement of the heat exchange fins 6 further optimizes the overall heat exchange efficiency. The addition of a guide plate 7 optimizes the flue gas flow direction, ensuring thorough turbulence and mixing of the flue gas as it passes through each heat exchange unit.

[0045] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. An elliptical tube economizer, characterized in that: It includes a support frame, heat exchange tubes, U-shaped connecting pipes, an inlet, and an outlet. The support frame is fixed on both sides, and several heat exchange tubes are horizontally connected between the support frame to form a multi-layer, multi-column matrix. The heat exchange tubes are connected at their ends by U-shaped connecting pipes to form a medium channel. The top of the medium channel is connected to the inlet, and the bottom of the medium channel is connected to the outlet. The heat exchange tubes have an elliptical cross-section, and heat exchange fins are fixedly provided on the outer wall of the heat exchange tubes. The heat exchange fins are inclined.

2. The elliptical tube economizer according to claim 1, characterized in that: The heat exchange fins on adjacent heat exchange tubes are tilted in opposite directions.

3. The elliptical tube economizer according to claim 1, characterized in that: The major axis of the elliptical heat exchange tube is inclined and forms an angle with the direction of flue gas flow.

4. The elliptical tube economizer according to claim 3, characterized in that: The major axes of the ellipses of adjacent heat exchange tubes are tilted in opposite directions.

5. The elliptical tube economizer according to any one of claims 1-4, characterized in that: The heat exchange fins on the upper heat exchange tubes are arranged more sparsely than those on the lower heat exchange tubes.

6. The elliptical tube economizer according to claim 1, characterized in that: Several layers of heat exchange tubes constitute a heat exchange unit. A flue gas guide zone is provided between adjacent heat exchange units. A guide plate connected to one side of the support is fixed in the flue gas guide zone. Adjacent guide plates are connected to supports on different sides to form an S-shaped flue gas channel.

7. The elliptical tube economizer according to claim 1, characterized in that: The heat exchange tube is equipped with a turbulence generator inside.

8. The elliptical tube economizer according to claim 1, characterized in that: The heat exchange tubes and heat exchange fins are coated with a hydrophobic and anti-corrosion coating.

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