Heat exchanger with waste heat utilization and cold end corrosion prevention

Abstract

This invention provides a heat exchange device for waste heat utilization and cold-end corrosion prevention, comprising an air inlet box, a heat exchange box, a negative pressure device, an air outlet main pipe, a hot air return pipe, and several heat exchange units. The heat exchange box has a waste heat channel. Each heat exchange unit has two ends connected to the air inlet box and the input end of the negative pressure device, respectively, and each heat exchange unit extends through the waste heat channel. The negative pressure device is connected to the air outlet main pipe. The air outlet main pipe is also connected to one end of the hot air return pipe. The other end of the hot air return pipe extends into the waste heat channel, then extends out from the waste heat channel and connects to the air inlet box, thereby returning a portion of the high-temperature air after heat exchange to the air inlet box. This heat exchange device can increase the air temperature drawn into the heat exchange units, preventing the formation of a corrosive ash layer at the cold end of the heat exchange units due to excessively low temperatures, completely solving the technical problem of corrosive ash accumulation inside the device, extending the service life of the heat exchange device, and saving maintenance and repair costs.

Description

Technical Field

[0001] This invention relates to the field of heat exchange technology, and more specifically, to a heat exchange device for waste heat utilization and cold-end corrosion prevention. Background Technology

[0002] Heat exchange devices mainly include shell-and-tube type, heat pipe type, plate type and other heat exchange methods; their working principle is that the hot end and cold end exchange heat through two sets of mutually closed airflows in a circulating flow. The waste heat (also known as residual heat) emitted by the hot end is absorbed through the medium such as tubes or plates, so that the heat of the medium at the cold end increases. Then, the heat after the medium is heated is absorbed away through airflow or other means.

[0003] Current heat exchange devices have the following shortcomings:

[0004] 1. The low temperature at the cold end of the heat exchanger leads to indirect heat exchange between the cold air and the low-temperature flue gas, causing corrosive components in the flue gas to deposit. Therefore, a corrosive ash layer easily forms in the low-temperature region, corroding the cold-end heat exchange unit. Plate heat exchangers require manual laser sealing welding to connect the heat exchange plates and end plates, resulting in high manufacturing costs, difficult maintenance, and the need for complete section replacement, leading to high maintenance and repair costs. Currently, some heat exchangers have added preheating devices to preheat the air before inputting it, preventing corrosive ash layers from forming at the cold end due to excessively low temperatures. However, this method requires additional preheating devices, increasing costs and space. Furthermore, the preheating device input is low-temperature air, where corrosive ash layers still form; the problem is merely relocated.

[0005] Second, the heat absorption air outlet end adopts negative pressure extraction. The suction force will make the negative pressure in the middle of the air channel cross section large and the negative pressure around the perimeter small, resulting in uneven airflow of heat absorption air into or through each heat exchange tube or heat exchange plate, thus causing insufficient heat exchange in the surrounding heat exchange tubes or heat exchange plates.

[0006] Third, the unreasonable insulation structure leads to a large loss of heat from the emitted hot flue gas, resulting in unsatisfactory heat exchange efficiency.

[0007] Therefore, there is significant room for improvement in heat exchange devices. Summary of the Invention

[0008] To overcome the shortcomings and deficiencies of the existing technology, the purpose of this invention is to provide a heat exchange device for waste heat utilization and cold end corrosion prevention. This heat exchange device can increase the air temperature at the intake heat exchange unit, avoid the formation of a corrosive ash layer at the cold end of the heat exchange unit due to excessively low temperature, completely solve the technical problem of corrosive ash accumulation inside the device, extend the service life of the heat exchange device, and save maintenance and repair costs.

[0009] To achieve the above objectives, the present invention is implemented through the following technical solution: a heat exchange device for waste heat utilization and cold end corrosion prevention, comprising an air inlet box with an air inlet, a heat exchange box, a negative pressure device, an air outlet main pipe, a hot air return pipe, and several heat exchange units; the heat exchange box is provided with a waste heat channel; the waste heat channel has a smoke inlet and a smoke outlet; both ends of each heat exchange unit are respectively connected to the air inlet box and the input end of the negative pressure device, and each heat exchange unit passes through the waste heat channel; the output end of the negative pressure device is connected to the air outlet main pipe, so that under the action of the negative pressure device, the air in the air inlet box flows through the heat exchange unit and is output to the air outlet main pipe, and absorbs the waste heat of the discharged hot flue gas in the waste heat channel during the flow through the heat exchange unit;

[0010] The main air outlet pipe is also connected to one end of the hot air return pipe; the other end of the hot air return pipe passes through the waste heat channel and is then connected to the air inlet box to realize the return of some of the high-temperature air after heat exchange to the air inlet box.

[0011] In this invention, the heat exchange device has a waste heat channel whose inlet is connected to the exhaust port of an external combustion device (such as a kiln heating section) to receive the hot flue gas emitted by the combustion device. The exhaust port of the waste heat channel is connected to the external space through a waste gas treatment process to purify the flue gas before it is discharged into the external space. Under the negative pressure of the negative pressure device, external air is drawn in through the inlet of the air inlet box, flows through the heat exchange unit, and converges at the negative pressure device before being output to the main exhaust pipe. Since the heat exchange unit runs through the waste heat channel, the air absorbs the waste heat from the emitted hot flue gas in the waste heat channel as it flows through the heat exchange unit, thus forming clean, high-temperature air.

[0012] After the high-temperature air flows into the outlet duct, a portion of it flows back into the inlet box through the hot air return duct to mix with the newly drawn-in low-temperature air. This increases the air temperature at the heat exchange unit, preventing corrosive dust accumulation at the cold end of the heat exchange unit due to excessively low temperatures, extending the service life of the heat exchange device, and saving maintenance and repair costs. Compared to using a preheating device to preheat the air before inputting it into the heat exchange device, this invention eliminates the need for a preheating device and avoids the need to relocate easily corrosive dust accumulation sites to other devices, completely solving the technical problem of internal corrosive dust accumulation. It also saves on preheating device costs and energy consumption. The hot air return duct runs through the waste heat channel, reducing energy loss of the returning high-temperature air and further ensuring the heat of the returning high-temperature air.

[0013] Preferably, a wrapping plate is detachably connected to each side of the heat exchange box; a gap is left between the wrapping plate and the outer wall of the heat exchange box to form a sandwich channel; the air inlet of the air inlet box is connected to the external space through the sandwich channel. External air first flows through the sandwich channel, carrying away the heat from the outer wall of the heat exchange box, and then enters the air inlet box; on the one hand, it can further utilize the waste heat and avoid heat loss, and on the other hand, it can reduce the temperature on the outside of the heat exchange device and improve the safety of use.

[0014] Preferably, the upper end of the wrapping plate is connected to the outer wall of the heat exchange box, thus sealing the top of the interlayer channel; the bottom of the interlayer channel forms an air inlet communicating with the external space. Sealing the top of the interlayer channel effectively reduces dust ingress and prevents warm air from escaping upwards; air is drawn in from the bottom of the interlayer channel upwards, effectively reducing dust carried in the inhaled air and improving its cleanliness.

[0015] Preferably, the connection points of all heat exchange units and the air inlet box together form a heat exchange unit connection area; the air inlet is located on the side of the air inlet box closest to the heat exchange box, and is located on the outer side of the heat exchange unit connection area. In the air inlet box, the air absorbed by the negative pressure enters from the air inlet on the outer side of the heat exchange unit connection area, flows through the side first and then towards the center, so that the air can be evenly drawn away by the negative pressure, thereby making the air flow more evenly into each heat exchange unit and improving the heat exchange effect.

[0016] Preferably, the two sides of the air inlet box protrude from the heat exchange box; the areas of the air inlet box protruding from the heat exchange box are opposite to the position of the interlayer channel and are provided with air inlets.

[0017] Preferably, it also includes an air outlet box and a heat exchange manifold; the air inlet box, heat exchange box, air outlet box and heat exchange manifold are arranged in sequence; each heat exchange unit extends out from the waste heat channel and is connected to the input end of the negative pressure device through the air outlet box and the heat exchange manifold.

[0018] The hot air return pipeline includes a return section one, a return air box, and a return section two; the two ends of the return section one are connected to the main air outlet and the return air box, respectively; one end of the return section two is connected to the return air box, and the other end of the return section two extends into the waste heat channel, and then extends out from the waste heat channel to connect with the air inlet box.

[0019] Preferably, the heat exchange box is provided with several partitions, so that the waste heat channel is in a tortuous shape; each partition is provided with mounting holes that match the cross-sectional shape and size of the heat exchange unit; each heat exchange unit is respectively installed through the mounting holes.

[0020] Preferably, the heat exchange box includes a central housing, an upper flue gas connector connected above the central housing, and a lower flue gas connector connected below the central housing; each partition is spaced apart in the central housing; the upper flue gas connector, the central housing, and the lower flue gas connector together form a waste heat channel; the flue gas inlet of the waste heat channel is located in the upper flue gas connector or the lower flue gas connector; the flue gas outlet of the waste heat channel is located in the upper flue gas connector or the lower flue gas connector; and the hot air return pipe passes through the upper flue gas connector or the lower flue gas connector.

[0021] Preferably, the lower flue gas connector has a cleaning port that communicates with the waste heat channel; the cleaning port is detachably covered with a cleaning cover.

[0022] Preferably, the heat exchange unit is a heat exchange tube or a heat exchange plate. An adjustment device is provided on the hot air return pipeline to adjust the return flow rate of the high-temperature air.

[0023] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0024] 1. The heat exchange device of the present invention increases the air temperature at the intake heat exchange unit, which can prevent the formation of a corrosive ash layer at the cold end of the heat exchange unit due to excessively low temperature, thus extending the service life of the heat exchange device and saving maintenance and repair costs; it completely solves the technical problem of corrosive ash accumulation inside the device without having to transfer the easily corrosive ash accumulation location to other devices; and it eliminates the need for a preheating device, saving preheating device costs and energy consumption costs.

[0025] 2. The heat exchange device of the present invention can reduce the energy loss of the return high-temperature air and further ensure the heat of the return high-temperature air; the hot air return pipeline is equipped with an adjustment device to adjust the return flow rate of the high-temperature air.

[0026] 3. The heat insulation structure of the heat exchange device of the present invention can further utilize waste heat, avoid heat loss, reduce the temperature outside the heat exchange device, and improve the safety of use; air is drawn in from the bottom to the top of the interlayer channel, which can effectively reduce the dust carried in the inhaled air and improve the cleanliness of the inhaled air.

[0027] 4. The heat exchange device of the present invention can make air flow into each heat exchange unit more evenly, thereby improving the heat exchange effect. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the heat exchange device of the present invention;

[0029] Figure 2 This is one of the cross-sectional schematic diagrams of the heat exchange device of the present invention;

[0030] Figure 3 This is a cross-sectional schematic diagram of the heat exchange device of the present invention after the heat exchange unit is hidden;

[0031] Figure 4 This is the second cross-sectional schematic diagram of the heat exchange device of the present invention;

[0032] Figure 5 This is a schematic diagram of the airflow direction of the heat exchange device of the present invention;

[0033] Figure 6 This is a schematic diagram of the air inlet box structure of the heat exchange device of the present invention;

[0034] Figure 7 This is a schematic diagram of the lower flue gas communication device structure of the heat exchange device of the present invention;

[0035] Among them, 1 is the air inlet box, 2 is the heat exchange box, 3 is the air outlet box, 4 is the heat exchange manifold, 5 is the main air outlet pipe, 6 is the negative pressure device, 7 is the return air box, 8 is the first return section, 9 is the second return section, 10 is the heat exchange tube, 11 is the upper flue gas connector, 12 is the lower flue gas connector, 13 is the partition, 16 is the wrapping plate, 17 is the air inlet, 18 is the connection with the heat exchange tube, and 19 is the ash removal port. Detailed Implementation

[0036] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0037] Example 1

[0038] like Figures 1 to 7 As shown in the figure, this embodiment of a heat exchange device for waste heat utilization and cold end corrosion prevention includes an air inlet box 1, a heat exchange box 2, a negative pressure device 6, an air outlet main pipe 5, a hot air return pipe, and several heat exchange units, and also includes an air outlet box 3 and a heat exchange manifold 4. In this embodiment, the heat exchange unit is a heat exchange tube 10.

[0039] The air inlet box 1, heat exchange box 2, air outlet box 3, and heat exchange manifold 4 are arranged sequentially. The heat exchange box 2 includes a central housing, an upper flue gas connector 11 connected to the upper part of the central housing, and a lower flue gas connector 12 connected to the lower part of the central housing. Several partitions 13 are provided at intervals in the central housing; the upper flue gas connector 11, the central housing, and the lower flue gas connector 12 together form a waste heat channel; the waste heat channel has a tortuous shape.

[0040] The waste heat channel has a flue gas inlet and a flue gas outlet. The flue gas inlet of the waste heat channel is connected to the hot flue gas discharge port of external combustion equipment (such as the heating section of a kiln) to receive the hot flue gas discharged from the combustion equipment. The flue gas outlet of the waste heat channel is connected to the external space and is purified through waste gas treatment to discharge the flue gas into the external space. In this embodiment, both the flue gas inlet and the flue gas outlet are located in the upper flue gas connector 11; in practical applications, they can also be located in the lower flue gas connector.

[0041] The lower flue gas connector 12 preferably has a dust removal port 19 that communicates with the waste heat channel; the dust removal port 19 is equipped with a detachable dust removal cover, which can facilitate the cleaning of dust and residue.

[0042] Each partition 13 is provided with mounting holes that match the cross-sectional shape and size of the heat exchange tube 10. One end of each heat exchange tube 10 is connected to the air inlet box 1, and the other end of each heat exchange tube 10 extends into the waste heat channel, then protrudes from the waste heat channel and connects to the input end of the negative pressure device 6 through the air outlet box 3 and the heat exchange manifold 4. In the waste heat channel, each heat exchange tube 10 is fixed by passing through the mounting holes. There are multiple heat exchange tubes, the number of which matches the number of mounting holes on the partition.

[0043] The output end of the negative pressure device 6 is connected to the main air outlet 5 so that, under the action of the negative pressure device 6, the air in the air inlet box 1 flows through the heat exchange tube 10 and is output to the main air outlet 5, and absorbs the waste heat of the exhaust gas in the waste heat channel during the flow through the heat exchange tube 10.

[0044] The main outlet pipe 5 is also connected to one end of the hot air return pipe; the other end of the hot air return pipe extends into the waste heat channel, and then extends out from the waste heat channel to connect with the air inlet box 1, so as to realize the return of some of the high-temperature air after heat exchange to the air inlet box 1. The hot air return pipe is equipped with a regulating device.

[0045] Specifically, the hot air return duct includes a first return section 8, a return air box 7, and a second return section 9. The two ends of the first return section 8 are connected to the main outlet air pipe 5 and the return air box 7, respectively. One end of the second return section 9 is connected to the return air box 7, and the other end extends into the waste heat channel, then extends out from the waste heat channel and connects to the inlet air box 1. The second return section 9 can be installed in the upper flue gas connector 11 or the lower flue gas connector 12. The first return section can be a single first return section or a combination of multiple first return units; similarly, the second return section can be a single second return section or a combination of multiple second return units.

[0046] The heat exchange device of the present invention draws in external air from the air inlet 17 of the air inlet box 1 through the negative pressure of the negative pressure device 6. The air flows from the air inlet box 1 through the heat exchange tube 10 and is output to the air outlet tube 5. Since the heat exchange tube 10 runs through the waste heat channel, the air absorbs the waste heat of the hot flue gas discharged in the waste heat channel during the flow of the heat exchange tube 10, thereby forming high temperature air.

[0047] After the high-temperature air flows into the outlet duct 5, a portion of it flows back into the inlet box 1 through the hot air return duct to mix with the newly drawn-in low-temperature air. This increases the air temperature at the intake heat exchange tube 10, preventing the formation of corrosive ash layers on the inlet box 1 and the cold end of the heat exchange tube 10 due to excessively low temperatures. This extends the service life of the heat exchange device and saves on maintenance and repair costs. This invention eliminates the need for a preheating device and avoids the need to relocate easily corrosive ash accumulation sites to other devices, completely solving the technical problem of internal corrosive ash accumulation. It also saves on preheating device costs and energy consumption. The hot air return duct runs through the waste heat channel, reducing energy loss of the returning high-temperature air and further ensuring its heat output. The hot air return duct is equipped with a regulating device, which can be a flow rate or velocity regulator, to adjust the return flow rate of the high-temperature air.

[0048] The heat exchange box 2 is detachably connected to two sides of a wrapping plate 16; a gap is left between the wrapping plate 16 and the outer wall of the heat exchange box 2 to form a sandwich channel; the air inlet 17 of the air inlet box 1 is connected to the external space through the sandwich channel. The upper end of the wrapping plate 16 is connected to the outer wall of the heat exchange box 2, so that the top of the sandwich channel is closed; the bottom of the sandwich channel forms an air inlet that communicates with the external space.

[0049] External air first flows through the interlayer channel, carrying away heat from the outer wall of heat exchange box 2, before entering the air inlet box 1. This not only further utilizes residual heat and prevents heat loss, but also reduces the temperature on the outside of the heat exchange device, improving operational safety. The top of the interlayer channel is sealed, effectively reducing dust ingress and preventing warm air from escaping upwards. Air is drawn in from below the interlayer channel, effectively reducing dust carried in the inhaled air and improving its cleanliness.

[0050] All the connections between the heat exchange tubes 10 and the air inlet box 1 together form the heat exchange tube 10 connection area; the air inlet 17 is located on the side of the air inlet box 1 near the heat exchange box 2, and is located outside the heat exchange tube 10 connection area. Furthermore, the two sides of the air inlet box 1 protrude from the two sides of the heat exchange box 2; the area of ​​the air inlet box 1 protruding from the two sides of the heat exchange box 2 is opposite to the position of the interlayer channel, and an air inlet 17 is provided therein.

[0051] In the air inlet box 1, the air absorbed by the negative pressure enters from the air inlet 17 on the outside of the heat exchange tube 10 connection area. It first passes through the side and then flows towards the middle position, so that the air can be evenly drawn away by the negative pressure, thereby making the air flow into each heat exchange tube 10 more evenly and improving the heat exchange effect.

[0052] Example 2

[0053] This embodiment provides a hot air recirculation heat exchanger, which differs from Embodiment 1 in that the heat exchange unit in this embodiment is a heat exchange plate. External air flows from the air inlet box through the internal air ducts of each heat exchange plate and is output to the main air outlet. The remaining structure of this embodiment is the same as that of Embodiment 1.

[0054] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A heat exchange device for waste heat utilization and cold-end corrosion prevention, characterized in that: The system includes an air inlet box with an air inlet, a heat exchange box, a negative pressure device, a main air outlet pipe, a hot air return pipe, and several heat exchange units. The heat exchange box has a waste heat channel with a smoke inlet and a smoke outlet. Each heat exchange unit is connected to the air inlet box and the input end of the negative pressure device at both ends, and each heat exchange unit passes through the waste heat channel. The output end of the negative pressure device is connected to the main air outlet pipe, so that under the action of the negative pressure device, the air in the air inlet box flows through the heat exchange units and is output to the main air outlet pipe, and absorbs the waste heat of the discharged hot flue gas in the waste heat channel during the flow through the heat exchange units. The heat exchange units are heat exchange tubes or heat exchange plates. The main outlet pipe is also connected to one end of the hot air return pipe; the other end of the hot air return pipe passes through the waste heat channel and is then connected to the air inlet box to realize the return of some of the high-temperature air after heat exchange to the air inlet box. The heat exchange box is detachably connected to two sides with wrapping plates; a gap is left between the wrapping plates and the outer wall of the heat exchange box to form a sandwich channel. The air inlet of the air inlet box is connected to the external space through an interlayer channel; It also includes an air outlet box and a heat exchange manifold; the air inlet box, heat exchange box, air outlet box and heat exchange manifold are arranged in sequence; each heat exchange unit extends out from the waste heat channel and is connected to the input end of the negative pressure device through the air outlet box and the heat exchange manifold. The hot air return pipeline includes a return section one, a return air box, and a return section two; the two ends of the return section one are connected to the main air outlet and the return air box, respectively; one end of the return section two is connected to the return air box, and the other end of the return section two extends into the waste heat channel, and then extends out from the waste heat channel to connect with the air inlet box. The heat exchange box is provided with several partitions, so that the waste heat channel is in a tortuous shape; each partition is provided with mounting holes that match the cross-sectional shape and size of the heat exchange unit; each heat exchange unit is respectively installed through the mounting holes.

2. The heat exchange device for waste heat utilization and cold end corrosion prevention according to claim 1, characterized in that: The upper end of the wrapping plate is connected to the outer wall of the heat exchange box, thus sealing the top of the interlayer channel; the bottom of the interlayer channel forms an air inlet that communicates with the external space.

3. The heat exchange device for waste heat utilization and cold-end corrosion prevention according to claim 1, characterized in that: All the connection points of the heat exchange units and the air inlet box together form the heat exchange unit connection area; the air inlet is located on the side of the air inlet box close to the heat exchange box, and is located outside the heat exchange unit connection area.

4. The heat exchange device for waste heat utilization and cold end corrosion prevention according to claim 3, characterized in that: The air inlet box protrudes from the heat exchange box on both sides; the areas of the air inlet box protruding from the heat exchange box are opposite to the interlayer channel and have air inlets.

5. The heat exchange device for waste heat utilization and cold end corrosion prevention according to claim 1, characterized in that: The heat exchange box includes a central housing, an upper flue gas connector connected above the central housing, and a lower flue gas connector connected below the central housing; various partitions are respectively spaced out in the central housing; the upper flue gas connector, the central housing, and the lower flue gas connector together form a waste heat channel; the flue gas inlet of the waste heat channel is located in the upper flue gas connector or the lower flue gas connector; the flue gas outlet of the waste heat channel is located in the upper flue gas connector or the lower flue gas connector; the hot air return pipe passes through the upper flue gas connector or the lower flue gas connector.

6. The heat exchange device for waste heat utilization and cold end corrosion prevention according to claim 5, characterized in that: The lower flue gas connector has a cleaning port that communicates with the waste heat channel; the cleaning port is detachably covered with a cleaning cover.

7. The heat exchange device for waste heat utilization and cold end corrosion prevention according to any one of claims 1 to 6, characterized in that: The hot air return pipe is equipped with an adjustment device.

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