Waste heat utilization device of boiler for changing fire coal into biomass particles

Abstract

The utility model discloses a boiler waste heat utilization device for changing fire coal into biomass particles, which belongs to the field of boiler waste heat utilization and comprises a heat exchange tube and a bent tube. And rib plates are arranged at the end parts of the heat exchange tubes. The bent pipe is arranged on the side, away from the heat exchange pipe, of the rib plate and communicates with the heat exchange pipe, and a connecting flange is arranged at the end of the bent pipe. The pipe openings of the two bent pipes, located at the same end, of every two adjacent heat exchange pipes are oppositely arranged, the two connecting flanges between the two bent pipes can be attached to each other, and the two connecting flanges are detachably connected through a connecting piece. Every two adjacent heat exchange pipes communicate with each other through the corresponding bent pipes formed on the heat exchange pipes and are connected through the connecting flanges on the two bent pipes, the two bent pipes are in flange connection with single pipe openings only through the two flanges, the number of bolts needed for flange connection is greatly reduced, and the heat exchange efficiency is improved. And therefore, the manpower and material resource cost during assembly and disassembly of the waste heat utilization device is reduced, and the cleaning efficiency of the waste heat utilization device is improved.

Description

Technical Field

[0001] This utility model belongs to the field of boiler waste heat utilization, specifically a waste heat utilization device for coal-fired boilers converted to biomass pellets. Background Technology

[0002] Converting coal-fired boilers to biomass pellet boilers is a significant current trend in boiler retrofitting. When converting low-pressure coal-fired boilers to biomass pellet boilers, the low ignition point, high volatile matter content, high hydrogen and oxygen content, and low ash melting point of biomass pellets, especially the water produced after hydrogen and oxygen combustion, lead to increased moisture content in the flue gas. This necessitates corresponding adjustments to the boiler's operating parameters. To prevent coking, the intake air volume needs to be increased. For example, some improved biomass boilers have doubled the original air volume and adopted a design that partially recirculates hot air to the furnace to improve heat utilization. However, due to the high moisture content in the flue gas after biomass fuel combustion, this high moisture content in the intake air further lowers the ash melting point, exacerbating the coking problem.

[0003] In older boilers, the internal structure is fixed, and modifications to other parts, except for the feeding system, are difficult. Therefore, some biomass boilers employ an economizer installed at the flue outlet to recover waste heat and improve thermal efficiency. The economizer uses multiple horizontally arranged series-parallel heat exchange tubes for heat exchange; however, this static waste heat recovery structure with small tube wall gaps suffers from severe coking problems. Coking reduces the exhaust efficiency inside the flue, thus affecting the boiler's thermal efficiency.

[0004] To ensure boiler thermal efficiency, the frequency of cleaning heat exchange pipes must be increased. Furthermore, to improve cleaning effectiveness, multiple heat exchange tubes need to be disassembled and cleaned individually. In a conventional economizer, the two heat exchange tubes are connected by a U-bend, with flanges connecting the U-bend to each tube. Each U-bend requires at least eight bolts for securing it. This not only expends significant manpower and resources for the overall assembly and disassembly of the economizer but also substantially increases the overall cleaning time. Utility Model Content

[0005] The purpose of this invention is to provide a waste heat utilization device for coal-fired biomass pellet boilers to solve the problems mentioned in the prior art.

[0006] A waste heat utilization device for coal-to-biomass pellet boilers is provided, comprising:

[0007] A heat exchange tube, wherein the ends of the heat exchange tube are provided with stiffeners;

[0008] A bend is provided on the side of the stiffener away from the heat exchange tube and is connected to the heat exchange tube. A connecting flange is provided at the end of the bend.

[0009] Two bends at the same end of two adjacent heat exchange tubes are arranged opposite each other, and the two connecting flanges between the two bends can fit together. The two connecting flanges are detachably connected by a connector.

[0010] Furthermore, the connecting flange and the stiffening plate are integrally formed. This integral forming of the connecting flange and the stiffening plate does not hinder the fixing function of the connecting flange, and at the same time, it can shorten the overall length of the waste heat recovery device in the length direction of the heat exchanger.

[0011] Furthermore, the inner cavity of the bent pipe is formed between the inner wall of the stiffening plate and the inner wall of the bent pipe, allowing the bent pipe to pass through the stiffening plate. By utilizing the inner wall of the stiffening plate to form part of the inner cavity of the bent pipe, the structural length of the waste heat utilization device occupied by the bent pipe in the length direction of the heat exchanger can be shortened, thereby shortening the overall length dimension of the waste heat utilization device in the length direction of the heat exchanger.

[0012] Furthermore, the connector includes a plurality of bolts and a plurality of nuts, wherein the bolts sequentially pass through two connecting flanges and are threadedly connected to the nuts. The connecting flanges are connected to the nuts via bolts, resulting in a simple connection method and a relatively compact structure.

[0013] Furthermore, the connector includes several bolts, several nuts, and several clamping plates. The two connecting flanges are fitted together and clamped between the two clamping plates. The bolts pass through the two clamping plates sequentially and are threadedly connected to the nuts. This design eliminates the need for drilling holes in the connecting flanges, thus reducing the precision requirements for the assembly of the two connecting flanges.

[0014] Furthermore, the openings of two adjacent bends are respectively formed with an inwardly recessed notch and an outwardly protruding convex opening. The cooperation between the convex and recessed openings can improve the sealing effect of the connection between the two bends.

[0015] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0016] Adjacent heat exchange tubes are connected by bends formed on them and then connected by flanges on the two bends. This replaces the original U-shaped tubes, which required two flanges to connect the two pipe ends, with the two bends of this application connected to a single pipe end by only two flanges. This significantly reduces the number of bolts required for flange connections, thereby reducing the manpower and material costs of loading and unloading the waste heat recovery device and improving the cleaning efficiency of the waste heat recovery device. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this drawing 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 this drawing. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0018] Figure 1 This is one of the overall structural schematic diagrams of a boiler waste heat utilization device;

[0019] Figure 2 This is the second schematic diagram of the overall structure of the boiler waste heat utilization device;

[0020] Figure 3 for Figure 2 A partial structural schematic diagram of a waste heat recovery device for a medium-sized boiler.

[0021] Figure 4 This is the third schematic diagram of the overall structure of the boiler waste heat utilization device.

[0022] In the diagram: 1. Heat exchange tube; 11. Rib plate; 2. Bend; 21. Connecting flange; 22. Notch; 23. Raised opening; 3. Connector; 31. Bolt; 32. Nut; 33. Clamping plate. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this application clearer, the application is described and illustrated below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application. All other embodiments obtained by those skilled in the art based on the embodiments provided in this application without inventive effort are within the scope of protection of this application.

[0024] Obviously, the accompanying drawings described below are merely some examples or embodiments of this application. Those skilled in the art can apply this application to other similar scenarios based on these drawings without any inventive effort. Furthermore, it is understood that although the efforts made in this development process may be complex and lengthy, for those skilled in the art related to the content disclosed in this application, any changes to design, manufacturing, or production based on the technical content disclosed in this application are merely conventional technical means and should not be construed as insufficient disclosure of the content of this application.

[0025] However, there may be instances where unnecessary detailed descriptions are omitted. For example, detailed descriptions of well-known matters or repetitive descriptions of essentially the same structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0026] Please see Figure 1 As shown in the figure, the waste heat utilization device for a coal-to-biomass pellet boiler in this embodiment of the present invention includes a heat exchange tube 1 and a bend 2. A stiffener 11 is provided at the end of the heat exchange tube 1. The bend 2 is located on the side of the stiffener 11 away from the heat exchange tube 1 and communicates with the heat exchange tube 1. A connecting flange 21 is provided at the end of the bend 2. The two bends 2 located at the same end of two adjacent heat exchange tubes 1 are arranged opposite each other. The two connecting flanges 21 between the two bends 2 can fit together, and the two connecting flanges 21 are detachably connected by a connector 3.

[0027] The waste heat recovery device is formed by stacking multiple heat exchange tubes 1. Multiple fins are installed around the periphery of each heat exchange tube 1 to improve heat exchange efficiency and provide structural separation. Adjacent heat exchange tubes 1 are connected in series via bends 2, allowing water to circulate within the device and exchange heat with the high-temperature flue gas. The bends 2 are integrally formed with the heat exchange tubes 1 and stiffeners 11. When the heat exchange tubes 1 are stacked, the stiffeners 11 serve a load-bearing and structural separation function. During installation, the openings of adjacent bends 2 are aligned, and the connecting flanges 21 on the two bends 2 are fitted together and fixed and sealed using connectors 3. This application changes the extension direction of the heat exchange tube openings by using bends 2, reducing the original requirement of two openings to a single sealing structure, significantly reducing the number of bolts required, alleviating the pressure of installing and removing the heat exchange tubes 1, and improving cleaning efficiency.

[0028] Please see Figure 2 As shown, this application changes the arrangement direction of the connecting flange 21, resulting in a longer pipe structure consisting of the heat exchange tube 1, the bend 2, and the connecting flange 21 compared to a conventional economizer (mainly due to the additional structure brought by the connecting flange 21). To save space in the length direction of the waste heat recovery device along the heat exchange tube 1, the connecting flange 21 and the stiffening plate 11 can be integrally formed, thereby causing the bend 2 to move closer to the stiffening plate 11. At the same time, the integral forming of the connecting flange 21 and the stiffening plate 11 can enhance the structural strength and stability of the bend 2.

[0029] Further, please refer to Figure 3As shown, the inner cavity of the bend 2 is formed between the inner wall of the stiffener 11 and the inner wall of the bend 2, allowing the bend 2 to pass through the stiffener 11. After hollowing out the side wall portion of the stiffener 11 to form a pipe wall structure, and integrally forming it with the bend 2, the length dimensions of the bend 2 and the connecting flange 21 structure in the length direction of the heat exchange tube 1 can be further reduced, making the waste heat utilization device structure more compact.

[0030] In one specific embodiment, please refer to Figure 1 As shown, the connector 3 includes several bolts 31 and several nuts 32. The bolts 31 pass through two connecting flanges 21 in sequence and are threadedly connected to the nuts 32. In this design, bolt holes need to be drilled on the connecting flanges 21. Since multiple heat exchange tubes 1 need to be connected in series, the drilling accuracy of the bolt holes on the connecting flanges 21 is required to ensure that each heat exchange tube 1 can be assembled with each other. However, the fixing structure of this connector 3 is relatively simple, and the operation during installation and removal is relatively convenient.

[0031] In one specific embodiment, please refer to Figure 4 As shown, the connector 3 includes several bolts 31, several nuts 32, and several clamping plates 33. Two connecting flanges 21 are fitted together and clamped between two clamping plates 33. The bolts 31 pass through the two clamping plates 33 sequentially and are threadedly connected to the nuts 32. This design eliminates the need to drill bolt holes in the connecting flanges 21, thus requiring lower machining precision for the connecting flanges 21; the goal is simply for the two connecting flanges 21 to fit tightly together to achieve a seal. However, this connector 3 has a relatively complex fixing structure and uses a relatively large number of parts.

[0032] Please see Figure 2 and Figure 3 As shown, the openings of two adjacent bends 2 respectively form an inwardly recessed notch 22 and an outwardly protruding convex opening 23. The cooperation between the convex opening 23 and the notch 22 can improve the sealing effect of the connection between the two bends 2 and prevent the two bends 2 from shifting relative to each other during the connection process.

[0033] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A waste heat utilization device for coal-to-biomass pellet boilers, characterized in that, include: Heat exchange tube (1), the end of which is provided with stiffener (11). The bend (2) is located on the side of the stiffener (11) away from the heat exchange tube (1) and is connected to the heat exchange tube (1). The end of the bend (2) is provided with a connecting flange (21). Two adjacent heat exchange tubes (1) are located at the same end of two bends (2) with their openings facing each other. The two connecting flanges (21) between the two bends (2) can fit together. The two connecting flanges (21) can be detachably connected by a connector (3). The connecting flange (21) and the stiffening plate (11) are integrally formed. The inner cavity of the pipe (2) is formed between the inner wall of the stiffening plate (11) and the inner wall of the pipe (2), so that the pipe (2) passes through the stiffening plate (11).

2. The waste heat utilization device for a coal-to-biomass pellet boiler according to claim 1, characterized in that, The connector (3) includes several bolts (31) and several nuts (32). The bolts (31) pass through the two connecting flanges (21) in sequence and are threadedly connected to the nuts (32).

3. The waste heat utilization device for a coal-to-biomass pellet boiler according to claim 1, characterized in that, The connector (3) includes several bolts (31), several nuts (32) and several clamping plates (33). The two connecting flanges (21) are fitted together and clamped between the two clamping plates (33). The bolts (31) pass through the two clamping plates (33) in sequence and are threadedly connected to the nuts (32).

4. The waste heat utilization device for a coal-to-biomass pellet boiler according to claim 1, characterized in that, The openings of two adjacent bends (2) respectively form an inwardly recessed notch (22) and an outwardly protruding notch (23).

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