JP2021530668A - Butterfly type fin tube heat exchanger - Google Patents

Abstract

The present invention includes a heat exchange tube (1) and a plurality of sets of fins (2) provided in the heat exchange tube (1), and each set of fins (2) is provided on both sides of the heat exchange tube (1). It is a butterfly structure composed of two half butterfly type fins (2) arranged symmetrically with each other, and each of the four corners of each half butterfly type fin (2) has an arc angle (3) with a radius of curvature of 10 mm to 100 mm. ), A butterfly type fin tube heat exchanger is provided. The heat exchanger effectively reduces acid corrosion, erosion corrosion and stress corrosion of the heat exchanger, especially the heat exchange fin (2), realizes automatic dust removal, and improves the heat transfer performance and service life of the heat exchanger. Improve.

Description

The present invention relates to a low temperature corrosion resistant butterfly fin tube heat exchanger for recovering the thermal energy of flue gas in boilers, industrial kilns and power plants, and belongs to the field of waste heat utilization of flue gas at low temperature. It can be used to recover the thermal energy of flue gas.

The composition of flue gas in coal-fired boilers and industrial kilns is relatively complex, and flue gas contains large amounts of solid particulate matter, SOx, NOx, steam, etc. When the waste heat is recovered, the waste heat recovery of the high temperature flue gas can be realized as in the existing inventions CN103438746A, CN106091782A, CN103438746A, etc., considering the problem of waste heat recovery and dust removal of the heat exchanger, and the effect is remarkable. Is. However, when the temperature of the flue gas drops to the condensation temperature of the acidic flue gas, more importantly, acid corrosion and erosion corrosion, which affect the life of the heat exchanger, other than considering the accumulation and removal of dust. And the problem of avoiding the deterioration of the heat transfer performance of the heat exchanger is taken into consideration. Corrosion problems are an important factor affecting the life of heat exchangers.

In the waste heat recovery of dust-containing flue gas, the present invention aims to prevent dust and dirt from accumulating, easy cleaning, efficient heat exchange, and the structure of the flue gas side and the anticorrosion coating layer technology. From both sides, the useful life of the heat exchanger for recovering waste heat of flue gas will be extended by working together to solve difficult problems such as low temperature corrosion of flue gas and poor heat transfer performance.

The butterfly type fin tube heat exchanger according to one aspect of the present invention is
A butterfly structure including a heat exchange tube and a plurality of sets of fins provided on the heat exchange tube, each set of fins composed of two half-butterfly type fins symmetrically arranged on both sides of the heat exchange tube. Each of the four corners of each half-butterfly fin has an arc-shaped angle with a radius of curvature of 10 mm to 100 mm, and a composite anticorrosion coating layer is applied to the outer surfaces of the half-butterfly fin and the heat exchange tube.

Preferably, in the butterfly structure, the distance between the two half butterfly fins is 6 mm to 100 mm.

Preferably, the arc angle is divided into an inner arc angle and an outer arc angle connected via a linear transition or an arc transition, and the radius of curvature of the outer arc angle is the curvature of the inner arc angle. Greater than the radius.

Preferably, the edges of each half-butterfly fin are provided with a first chamfer with a radius of curvature of 2 mm to 8 mm in the thickness direction.

Preferably, a second chamfer having a radius of curvature of 2 mm to 8 mm is formed at the connection portion between the half butterfly type fin and the heat exchange tube.

In the above aspect, the composite anticorrosion coating layer includes a base plating layer and an organic anticorrosion coating layer. The base plating layer is an amorphous nickel-copper phosphorus composite plating layer produced by adding second cerium sulfate as an additive, and the organic anticorrosion coating layer is a fluororesin, polyurethane, fluorocarbon resin or silicon coating layer. .. The heat exchange tube is a circular tube, an elliptical tube, or a flat tube.

When recovering waste heat from flue exhaust gas, which has a problem of acid corrosion, it is necessary to work together to solve the following three important problems. The first is to improve the heat transfer performance of the entire heat exchanger by achieving both enhanced heat exchange and the ability to remove accumulated dust with the fins on the flue gas side, and the second is the corresponding structural form. Achieve timely shedding and discharge of dust and acidic condensate to avoid clogging of the heat exchanger and extend the operating period of the heat exchanger. The third is acid corrosion and erosion. The use of anticorrosion control technology to mitigate corrosion is to effectively improve the useful life of heat exchangers. The present invention proposes a butterfly type fin tube heat exchanger based on multiple facility site surveys, organized analysis of common problems, and repeated test studies in various fields, and has the following advantages and remarkable advantages over the prior art. Has a good effect. In the present invention, (1), since the fins have a butterfly structure and the corner angles of the fins are all arcuate, the specific surface area of the easily corroded areas such as sharp angles and ridge angle positions can be effectively reduced, and the fins can be finned. It is possible to effectively alleviate the acid corrosion of the dust-containing flue gas and reduce the erosion wear of the dust-containing flue gas. As a result, when the dust-containing airflow impacts the front edge of the heat exchange tube or flows through the trailing edge of the negative pressure region, the collected dust and condensate fall off in a timely manner due to the action of gravity and are discharged. (3) By using the complete welding method and arc line transition at the connection point between the fin and the heat exchange pipe, the local stress at the position of the welding seam is reduced, and the stress corrosion and acid corrosion rate are effective. (4) The heat exchangers existing in the prior art are easily acid-corroded from both the structure and the coating layer, dust and condensate are difficult to be discharged, and the heat transfer efficiency is low. Compared to conventional heat exchangers for recovering waste heat from flue gas, it saves materials, prevents dust and liquid from accumulating, effectively reduces erosion wear, and has a long service life. It has the characteristics of. Therefore, the present invention can effectively solve the above-mentioned important problems, effectively suppress problems such as acid corrosion, and realize waste heat recovery of flue gas.

It is the schematic of one Example of the butterfly type fin tube heat exchanger which concerns on this invention. It is the schematic of another Example of the butterfly type fin tube heat exchanger which concerns on this invention. It is the schematic of the 3rd Example of the butterfly type fin tube heat exchanger which concerns on this invention. FIG. 2 is a schematic cross-sectional view taken along the line AA in FIG.

Hereinafter, the specific structure and operation process of the present invention will be further described with reference to the drawings.

As shown in FIG. 1, the butterfly type fin tube heat exchanger for preventing corrosion of the flue gas according to the present invention is provided in the heat exchange tube 1 and the heat exchange tube, and is symmetrical on both sides of the heat exchange tube, respectively. The four corners of each half-butterfly-type fin 2 include an arc-shaped angle 3 having a radius of curvature of 10 mm to 100 mm, including a plurality of sets of fins having a butterfly structure composed of two arranged half-butterfly-type fins 2. A composite anticorrosion coating layer is applied to the outer surfaces of the half butterfly type fin 2 and the heat exchange tube 1, and a circular tube may be selected as the heat exchange tube 1, and a deformed heat exchange tube such as an elliptical tube or a flat tube 1 may be selected. May be selected.

The heat exchange tube on the flue gas side has a low surface heat transfer coefficient, and in general, a rib is provided outside the heat exchange tube of the heat exchanger to increase the heat exchange area on the flue gas side. Achieve the purpose of improving the heat transfer performance of the heat exchanger. The rib types include integrated ribs, spiral ribs, and pin ribs. Since the composition of the flue gas is complicated, it contains particulate matter, and it easily condenses when it comes into contact with a low temperature surface, the flue gas stays upstream of the heat exchange tube when it flows through the vertically arranged heat exchange tube. There is a region, dust and acidic condensate are likely to accumulate in the retention region, and there is one negative pressure region downstream of the heat exchange tube, and dust adheres to the negative pressure region and acid corrosion of low-temperature flue gas. Is most likely to occur in conventional heat exchangers, unless the dust and acidic condensate accumulated on the leeward and leeward sides of the heat exchanger are removed in a timely manner, dust and dirt will accumulate, accumulate corrosion, and eventually. The clogging phenomenon is likely to occur, which affects the heat transfer performance and service life of the entire heat exchanger. The fin of the present invention can realize automatic dust removal in the retention area by using the butterfly structure, and since the corner angles of the fins are all arc-shaped, the specific surface area of the easily corroded area such as acute angle and ridge angle position. Can be effectively reduced, effectively mitigating acid corrosion of fins and reducing erosion (washout) wear of dust-containing flue gas.

Specifically, the arc angle 3 is divided into an inner arc angle 3a and an outer arc angle 3b connected via a linear transition portion or an arc transition portion (see FIG. 2), preferably an outer arc. The radius of curvature of the shape angle 3b may be designed to be larger than the radius of curvature of the inner arc angle, and thus strong erosion corrosion can be effectively prevented, the dust content is large, and the airflow. Suitable for high speeds. In the flow direction of the flue gas, at the upstream and downstream positions of the heat exchange pipe, there is a certain space H (see FIG. 2) between two symmetrically arranged half butterfly type fins, and the two halves. The distance H between the butterfly fins 2 is generally 6 mm to 100 mm, and the mixture of dust and the remaining acidic agglomerate always flows downward along the heat exchange tube to remove dust in a timely manner and the acidic condensate. Achieve the purpose of discharging. If the interval H is too small, clogging occurs and the heat exchanger is easily damaged. If the interval H is too large, the heat exchange strengthening ability of the fins is weakened and the heat transfer performance of the heat exchanger is low.

As shown in FIG. 3, the butterfly type fin tube heat exchangers are provided in two heat exchange tubes 1 and two heat exchange tubes, and are arranged symmetrically on both sides of each of the two heat exchange tubes. It includes a plurality of sets of fins having a butterfly structure composed of two half butterfly type fins 2.

The edges of each half-butterfly fin of the present invention are provided with a first chamfer 7 having a radius of curvature of preferably 2 to 8 mm in the thickness direction (see FIG. 4), and the structure of the first chamfer. Can reduce the erosion corrosion of the inflowing dust-containing flue gas, reduce the local specific surface area, and effectively reduce the rate at which the acidic condensate corrodes the coating layer on the fin surface. can. Since a second chamfer 4 having a radius of curvature of 2 to 8 mm is formed at the connection point between the half butterfly type fin 2 and the heat exchange tube 1, between the heat exchange tube 1 and the half butterfly type fin 2. Not only can stress corrosion be reduced, but acid corrosion can also be weakened by reducing the local specific surface area. Circular chamfers are provided in the thickness direction of the half-butterfly type fins 2 (see FIGS. 1 to 3), which not only helps reduce the local corrosion rate but also provides a high quality anticorrosion coating layer. Also useful for sputtering.

In the above embodiment, the composite anticorrosion coating layer is composed of an undercoat plating layer and an organic anticorrosion coating layer, and the undercoat plating layer is an amorphous nickel-copper phosphorus composite plating layer produced by adding a second cerium sulfate as an additive. The organic anticorrosion coating layer is a fluororesin, polyurethane, fluorocarbon resin or silicon coating layer. In this way, by suppressing the localized accelerated acid corrosion / corrosion of the coating layer, the service life of the entire heat exchanger is improved, and the corrosion of the acid solution cooperates from both the structure and the composite coating layer. It is effectively suppressed, the corrosion of the acidic condensate on the composite coating layer is significantly reduced, and the long service life of this heat exchanger and economical and stable operation are realized. Further, for each of the circular chamfers (first chamfer and second chamfer), a chamfer having a smooth curved structure such as an elliptical chamfer may be selected.

From the above, in the conventional fin tube heat exchanger, when the fins come into contact with the acidic condensate generated by the dust-containing flue gas, remarkable acid corrosion, impact corrosion and stress corrosion are likely to occur on the fins. The present invention uses half-butterfly fins and designs a large curvature structure over the corner angle, thickness direction, and contact position of complete welding between the heat exchange tube and the fins, and each set. By providing the interval H between the half-butterfly type fins of the above, a smooth transition of the position such as the bending angle of the fins is realized. Finally, by using a special composite anticorrosion coating layer structure, erosion corrosion and stress corrosion of the flue gas to the coating layer in the waste heat recovery process of the dust-containing flue gas are effectively reduced, and the dust-containing flue gas Acid corrosion is suppressed, automatic dust removal is realized, and ultimately the heat exchange structure of the heat exchanger is not corroded and the useful life of the heat exchanger is significantly extended.

1 Heat exchange tube 2 Half butterfly type fin 3 Arc angle 3a Inner arc angle 3b Outer arc angle 4 Second chamfer 7 First chamfer

Claims (9)

A butterfly type fin tube heat exchanger including a heat exchange tube (1) and a plurality of sets of fins provided in the heat exchange tube, and each set of fins is symmetrically arranged on both sides of the heat exchange tube. It has a butterfly structure composed of two half butterfly type fins, and each of the four corners of each half butterfly type fin (2) has an arc angle (3) with a radius of curvature of 10 mm to 100 mm, and the half butterfly type fins. A butterfly type fin tube heat exchanger characterized in that a composite anticorrosion coating layer is applied to the outer surface of (2) and the heat exchange tube (1). The butterfly type fin tube heat exchanger according to claim 1, wherein in the butterfly structure, the distance between the two half butterfly type fins (2) is 6 mm to 100 mm. The arc angle (3) is divided into an inner arc angle (3a) and an outer arc angle (3b) connected via a linear transition portion or an arc transition portion, and the outer arc angle (3b). The butterfly type fin tube heat exchanger according to claim 1, wherein the radius of curvature is larger than the radius of curvature of the inner arc angle (3a). The arc angle (3) is divided into an inner arc angle (3a) and an outer arc angle (3b) connected via a linear transition portion or an arc transition portion, and the outer arc angle (3b). The butterfly type fin tube heat exchanger according to claim 2, wherein the radius of curvature is larger than the radius of curvature of the inner arc angle (3a). The butterfly mold according to claim 3, wherein a first chamfer (7) having a radius of curvature of 2 mm to 8 mm is provided on the edge of each half butterfly mold fin (2) in the thickness direction. Fin tube heat exchanger. 5. The fifth aspect of the present invention is that a second chamfer (4) having a radius of curvature of 2 mm to 8 mm is formed at a connection portion between the half butterfly type fin (2) and the heat exchange tube (1). Butterfly type fin tube heat exchanger described in. The butterfly type fin tube heat exchanger according to claim 1, wherein the heat exchange tube (1) is a circular tube, an elliptical tube, or a flat tube. The butterfly type fin tube heat exchanger according to claim 1, wherein the composite anticorrosion coating layer includes a base plating layer and an organic anticorrosion coating layer. The base plating layer is an amorphous nickel-copper phosphorus composite plating layer produced by adding second cerium sulfate as an additive, and the organic anticorrosion coating layer is a fluororesin, polyurethane, fluorocarbon resin or silicon coating layer. The butterfly type fin tube heat exchanger according to claim 8, characterized in that.

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