Economizer with composite structure

Abstract

A composite structure economizer comprises a supporting piece (2) connected with a boiler flue gas channel (1), a composite plate pipe (3) connected with the supporting piece, a water inlet pipe pass box body (5) connected with the water inlet end of a nonmetal heat exchange pipe (4) of the composite plate pipe, and a water outlet pipe pass box body (6) connected with the water outlet end of the nonmetal heat exchange pipe (4) of the composite plate pipe (3). The upper maintenance cover plate (7) and the lower maintenance cover plate (8) are connected with a boiler flue gas channel; the composite plate tube (3) comprises a metal plate (9) and a non-metal heat exchange tube (4) embedded in the metal plate (9). According to the technical scheme, the non-metal heat exchange tubes are embedded into the metal plates, so that the technical problem that the economizer is not resistant to abrasion and corrosion in flue gas is solved, and the economizer has the advantages of being compact in structure, convenient to install, small in overhaul difficulty and the like.

Description

Technical Field

[0001] The invention relates to the technical field of boiler economizers, and in particular to a composite structure economizer. Background Art

[0002] Setting up economizers in the flue gas channel of coal-fired boilers can reduce the exhaust gas temperature, improve the thermal efficiency of the boiler, and have good economic and environmental benefits. At present, economizers for coal-fired boilers include fluoroplastic tube heat exchangers and metal tube heat exchangers represented by ND steel (including H-type and finned tubes).

[0003] Metal tube heat exchangers (including H-type and finned tubes) represented by ND steel have strong acid corrosion resistance, but the corrosion factors in flue gas are very complex. In order to ensure the safe operation of coal-fired boilers, economizers are generally protected by increasing the exhaust gas temperature. Therefore, it is difficult to reduce the flue gas temperature to the extreme by using ND steel economizers for deep flue gas cooling. When the flue gas flow rate of the finned shell and tube heat exchanger is low, the non-flow of flue gas between the fins is equivalent to the insulation layer, which restricts the improvement of heat exchange efficiency; if the flue gas flow rate is increased, the flue gas escapes from the part with the least resistance between the two finned tubes, and no effective heat exchange is carried out. At the same time, if the flue gas flow rate is increased, the resistance loss is large. Therefore, the temperature difference of most tubular heat exchangers is 40℃-50℃. Taking the condensed water coming out of the condenser at 40℃, the exhaust temperature is still 80℃-90℃ after passing through the heat exchanger. The waste heat of the flue gas is not fully recovered, especially the latent heat of low-temperature water vapor. Therefore, the heat recovery efficiency is not high. Many projects can achieve 1%-2% in theory. In actual operation, they are affected by multiple factors. Some flue gas temperatures are only reduced by 20-30℃ after passing through the flue gas economizer, and the heat recovery rate is extremely low. ND steel tube heat exchangers are large in size, occupy a large area, are heavy, and are difficult to install. The resistance loss of tubular heat exchangers is large, and the original induced draft fan configuration of the power plant needs to be changed when replacing them. ND steel tube heat exchangers are large in size and have a large axial length, so they cannot be thoroughly cleaned. Restricted by the corrosion resistance of the material, the life of ND steel tube flue gas economizers is generally low.

[0004] Fluoroplastic tubular heat exchangers are made of fluoroplastic tubes. The corrosion resistance of fluoroplastic tubes is not a problem in the flue gas of coal-fired boilers, but fluoroplastics are easy to decompose under high temperature conditions above 300°C. The heat transfer coefficient of fluoroplastic tubes is worse than that of ND steel, and the heat recovery rate is low. The installation difficulty of fluoroplastic tubular heat exchangers is the same as that of ND steel heat exchangers. Like ND steel heat exchangers, fluoroplastic tubular heat exchangers have large resistance losses, and replacement is easy to affect the balance of the original system. The surface of fluoroplastics itself has the property of non-stickiness, but the ash deposited between the tubes of the heat exchanger will form a mud ball with the entire heat exchanger after a certain period of time, sealing the heat exchanger as a whole. Due to its small tube spacing and long axial length, it is difficult to maintain and easily leads to overall scrapping. Affected by plastic aging and local accelerated aging, the life of plastic heat exchangers is restricted, and if blocked, it often leads to early scrapping.

[0005] Therefore, it is of great significance to develop economizers with new structures. Summary of the invention

[0006] In order to overcome the defects of the prior art, the present invention provides a composite structure economizer, which can solve the technical problems of economizer's poor wear and corrosion resistance in flue gas and low heat exchange efficiency, and effectively improve the waste heat recovery rate of gas boilers.

[0007] In order to solve the above technical problems, the composite structure economizer provided by the present invention includes a support connected to the boiler flue gas channel, a plurality of composite plate tubes connected to the support, an inlet pipe box connected to the water inlet end of the non-metallic heat exchange tube of the composite plate tube, an outlet pipe box connected to the water outlet end of the non-metallic heat exchange tube of the composite plate tube, an upper maintenance cover located above the composite plate tube and connected to the boiler flue gas channel, and a lower maintenance cover located below the composite plate tube and connected to the boiler flue gas channel; the composite plate tube includes a metal plate and a non-metallic heat exchange tube embedded in the metal plate.

[0008] As a further improved technical solution, the composite structure economizer provided by the present invention also has a cleaning pipe extending into between adjacent composite plate tubes.

[0009] As a further improved technical solution, the composite structure economizer provided by the present invention, the metal plate has a plurality of arc-shaped grooves, and the composite structure economizer also has a plurality of arc-shaped cover plates connected to the metal plate; the non-metallic heat exchange tubes are placed in the arc-shaped grooves, and the non-metallic heat exchange tubes are covered with the arc-shaped cover plates.

[0010] As a further improved technical solution, the composite structure economizer provided by the present invention has a plurality of tube cavities arranged at intervals on the metal plate, and the non-metallic heat exchange tubes are inserted into the tube cavities.

[0011] In the absence of conflict, the above improvements may be implemented individually or in combination.

[0012] The technical solution provided by the present invention embeds non-metallic heat exchange tubes into metal plates to solve the technical problem that the economizer is not resistant to wear and corrosion in flue gas, and has the characteristics of compact structure, easy installation, and low maintenance difficulty. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the present application, but do not constitute an improper limitation of the present invention. In the accompanying drawings: Figure 1 is a structural diagram of a composite structure economizer according to an embodiment; Figure 2 is a composite plate and tube arrangement diagram of a composite structure economizer of an embodiment; Figure 3 is a structural diagram of a composite plate tube of a composite structure economizer of an embodiment; Figure 4 This is one of the cross-sectional structural diagrams of the composite plate tube of the composite structure economizer of the embodiment; Figure 5 This is the second cross-sectional structural diagram of the composite plate tube of the composite structure economizer of the embodiment. Implementation

[0014] The embodiments of the present invention will be further described in detail below in conjunction with the accompanying drawings.

[0015] like Figures 1 to 3 The composite structure economizer shown includes a support member 2 connected to the boiler flue gas channel 1, a plurality of composite plate tubes 3 connected to the support member 2, an inlet pipe box 5 connected to the water inlet end of the non-metallic heat exchange tube 4 of the composite plate tube 3, an outlet pipe box 6 connected to the water outlet end of the non-metallic heat exchange tube 4 of the composite plate tube 3, an upper maintenance cover 7 located above the composite plate tube 3 and connected to the boiler flue gas channel 1, and a lower maintenance cover 8 located below the composite plate tube 3 and connected to the boiler flue gas channel 1; the composite plate tube 3 includes a metal plate 9 and a non-metallic heat exchange tube 4 embedded in the metal plate 9.

[0016] The metal plate 9 of the composite plate tube 3 is made of wear-resistant and corrosion-resistant metal plate, and the heat exchange tube 4 uses a non-metallic tube. During operation, the metal plate 9 is used to exchange heat with the flue gas. The metal plate 9 transfers heat to the non-metallic heat exchange tube 4, and the non-metallic heat exchange tube 4 transfers heat to the water in the tube. The use of metal plates to exchange heat with flue gas can greatly improve the heat exchange efficiency. The metal plate has high strength, wear resistance, corrosion resistance, and high heat transfer efficiency. The non-metallic heat exchange tube 4 is embedded in the metal plate 9 to protect the non-metallic heat exchange tube 4; the non-metallic heat exchange tube 4 is passed into the hot water exchange water to reduce the temperature of the non-metallic heat exchange tube 4, thereby improving the operating environment of the non-metallic heat exchange tube 4 and extending its service life. During inspection and maintenance, the upper maintenance cover 7 and the lower maintenance cover 8 can be removed, the equipment as a whole can be pulled out from the boiler flue gas channel 1, and the metal plate or non-metallic tube can be replaced. The technical solution provided by the present invention embeds non-metallic heat exchange tubes into metal plates to solve the technical problem that the economizer is not resistant to wear and corrosion in flue gas, and has the characteristics of compact structure, easy installation, and low maintenance difficulty.

[0017] like Figure 2As shown, the composite plate tubes 3 are arranged in parallel and staggered in the boiler flue gas channel 1. The parallel arrangement of the composite plate tubes 3 makes the flue gas flow resistance at each location the same, which facilitates the dispersion of the flue gas to the channels between the composite plate tubes 3 and avoids short-circuit wind. The staggered arrangement structure effectively disturbs the flue gas entering between the two composite plate tubes 3, further improving the heat exchange efficiency. The composite plate tubes 3 are parallel to the flue gas flow direction and perpendicular to the ground, with few corners for dust accumulation. The accumulated dust falls unimpeded along the composite plate tubes 3 under the action of gravity. At the same time, the larger gap between the composite plate tubes 3 can ensure the space for dust falling.

[0018] As one example, Figure 1 As shown, the composite structure economizer also has a cleaning pipe 10 extending between the composite plate tubes 3. The cleaning pipe 10 can clean the composite plate tubes 3.

[0019] As one example, Figure 4 As shown, the metal plate 9 of the composite structure economizer has a plurality of arc-shaped grooves 11, and the composite structure economizer also has a plurality of arc-shaped cover plates 12 connected to the metal plate 9; the non-metallic heat exchange tubes 4 are placed in the arc-shaped grooves 11, and the non-metallic heat exchange tubes 4 are covered with the arc-shaped cover plates 12.

[0020] As one example, Figure 5 As shown, the metal plate 9 of the composite structure economizer is provided with a plurality of tube cavities 13 at intervals, and the non-metallic heat exchange tubes 4 are inserted into the tube cavities 13 .

[0021] The metal plate 9 is formed in one piece or in separate pieces. Figure 4 As shown, the integrally formed metal plate 9 has arc-shaped grooves 11 and arc-shaped bosses, which can disturb the flue gas and enhance heat exchange. Figure 5 As shown, a plurality of tube cavities 13 are arranged at intervals by using a split-molded metal plate 9, and a non-metallic heat exchange tube 4 is inserted into the tube cavity 13. The non-metallic heat exchange tube 4 can be made of silicone tube, PE tube, etc. When the non-metallic heat exchange tube 4 is heated, the heat expansion causes the non-metallic heat exchange tube 4 to be closely attached to the arc groove 11, the arc cover plate 12 or the tube cavity 13, and the non-metallic heat exchange tube 4 is closely attached to the metal plate, thereby obtaining a higher heat transfer efficiency. The arc-shaped boss on the metal plate 9 effectively disturbs the flue gas entering between the two composite plate tubes 3, further improving the heat exchange efficiency.

[0022] Obviously, the present invention is not limited to the above preferred embodiments, and can also be transformed and improved in various forms within the spirit defined in the claims and the specification of the present invention, which can solve the same technical problems and achieve the expected technical effects, so it is not repeated. All solutions that can be directly or associatively derived from the contents disclosed by ordinary technicians in the field of the present invention, as long as they are within the spirit defined in the claims, also belong to the protection scope of the present invention.

Claims

1. A composite structure economizer, comprising a support member (2) connected to a boiler flue gas channel (1), a plurality of composite plate tubes (3) connected to the support member (2), a water inlet pipe box (5) connected to the water inlet end of the non-metallic heat exchange tube (4) of the composite plate tube (3), a water outlet pipe box (6) connected to the water outlet end of the non-metallic heat exchange tube (4) of the composite plate tube (3), an upper maintenance cover plate (7) located above the composite plate tube (3) and connected to the boiler flue gas channel (1), and a lower maintenance cover plate (8) located below the composite plate tube (3) and connected to the boiler flue gas channel (1); characterized in that: The composite plate tube (3) comprises a metal plate (9) and a non-metallic heat exchange tube (4) embedded in the metal plate (9).

2. The composite structure economizer according to claim 1, characterized in that: It also has a cleaning pipe (10) extending between adjacent composite plate pipes (3).

3. The composite structure economizer according to claim 1, characterized in that: The metal plate (9) has a plurality of arc-shaped grooves (11), and the composite structure economizer also has a plurality of arc-shaped cover plates (12) connected to the metal plate (9); the non-metallic heat exchange tubes (4) are placed in the arc-shaped grooves (11), and the non-metallic heat exchange tubes (4) are covered by the arc-shaped cover plates (12).

4. The composite structure economizer according to claim 1, characterized in that: The metal plate (9) is provided with a plurality of tube cavities (13) at intervals, and the non-metallic heat exchange tubes (4) are inserted into the tube cavities (13).

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