A boiler flue gas heat exchange device and system

Abstract

This utility model belongs to the field of industrial water supply technology and discloses a boiler flue gas heat exchange device and system. The boiler flue gas heat exchange device includes a first heat exchange component and a second heat exchange component installed on the flue of the boiler body. After the first heat exchanger exchanges heat with the water outlet of the air preheater, a three-way mixing valve is used to draw out and mix the water outlet of the first heat exchanger with the water outlet of the water supply tank, and send it to the second heat exchanger for further heat exchange, and finally enter the boiler body. This multi-stage heat exchange fully utilizes the waste heat of the flue gas to improve heat exchange efficiency and achieve energy saving. In particular, the mixing of the water outlet of the first heat exchanger with the water outlet of the water supply tank before the second heat exchange can balance the water quality and temperature. Balancing the water quality prevents scaling or corrosion, and balancing the temperature avoids thermal stress on the system caused by sudden changes in water temperature, further improving the stability and safety of the system.

Description

Technical Field

[0001] This utility model relates to the field of industrial water supply technology, and in particular to a boiler flue gas heat exchange device and system. Background Technology

[0002] A boiler is an energy conversion device. The energy input to a boiler includes the chemical energy of fuel and electrical energy. The boiler outputs steam, high-temperature water, or organic heat carriers with a certain amount of thermal energy. The flue gas temperature at the tail end of an industrial gas-fired boiler can reach around 200℃. An economizer is usually installed on the tail flue gas side to absorb the heat of the flue gas, thereby reducing the boiler exhaust temperature. At the same time, it makes full use of the waste heat of the flue gas to increase the boiler inlet water temperature and thus improve the heat exchange efficiency.

[0003] Traditional energy savers are single-unit, single-stage heat exchangers that directly use high-temperature flue gas to heat boiler feedwater from 100°C to 130°C before it enters the boiler. The outlet flue gas temperature of the energy saver is about 120°C, resulting in low heat exchange efficiency and low energy utilization. Utility Model Content

[0004] The purpose of this utility model is to provide a boiler flue gas heat exchange device and system that can make full use of the waste heat of flue gas to improve heat exchange efficiency and achieve energy saving.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] A boiler flue gas heat exchange device is disclosed, capable of heating feedwater for an air preheater and a water supply tank. The boiler flue gas heat exchange device includes a first heat exchange component and a second heat exchange component installed on the flue of the boiler body.

[0007] The first heat exchange component includes a first inlet pipe, a first heat exchanger, and a first outlet pipe connected in sequence. The first inlet pipe is used to connect to the outlet of the air preheater. The first outlet pipe is connected to the water supply tank through a three-way mixing valve. The first outlet pipe is also connected to the first inlet of the three-way mixing valve. The water supply tank can be connected to the second inlet of the three-way mixing valve.

[0008] The second heat exchange assembly includes a second inlet pipe, a second heat exchanger, and a second outlet pipe connected in sequence. The second inlet pipe is connected to the outlet of the three-way mixing valve, and the second outlet pipe is connected to the inlet of the boiler body. The flue is connected to the second heat exchanger and the first heat exchanger in sequence.

[0009] Preferably, the boiler flue gas heat exchange device further includes a temperature sensor for detecting the water temperature in the first inlet pipe, the first outlet pipe, the second inlet pipe, and the second outlet pipe.

[0010] Preferably, the boiler flue gas heat exchange device further includes a first regulating valve for regulating the water flow rate in the first water inlet pipe, the first water outlet pipe, the second water inlet pipe, and the second water outlet pipe.

[0011] Preferably, the boiler flue gas heat exchange device further includes a pressure gauge, which is used to detect the water pressure in the first inlet pipe, the first outlet pipe, the second inlet pipe, and the second outlet pipe.

[0012] Preferably, the boiler flue gas heat exchange device further includes a check valve, which is used to prevent backflow of water in the first inlet pipe, the first outlet pipe, the second inlet pipe, and the second outlet pipe.

[0013] Preferably, each of the first water inlet pipe, the first water outlet pipe, the second water inlet pipe, and the second water outlet pipe is provided with an exhaust port to discharge excess air from the first water inlet pipe, the first water outlet pipe, the second water inlet pipe, and the second water outlet pipe.

[0014] Preferably, each of the exhaust ports is equipped with a safety valve.

[0015] Preferably, both the first heat exchanger and the second heat exchanger are provided with drain outlets.

[0016] Preferably, each of the drain outlets is provided with a second regulating valve for regulating the water flow rate at the drain outlet.

[0017] A boiler flue gas heat exchange system includes a boiler body, an air preheater, a water supply tank, and the aforementioned boiler flue gas heat exchange device.

[0018] The beneficial effects of this utility model are:

[0019] This utility model proposes a boiler flue gas heat exchange device capable of heating the feedwater of an air preheater and a water supply tank. The boiler flue gas heat exchange device includes a first heat exchange component and a second heat exchange component installed on the flue of the boiler body. The first heat exchange component includes a first inlet pipe, a first heat exchanger, and a first outlet pipe connected in sequence. The first inlet pipe is used to connect to the outlet of the air preheater, and the first outlet pipe is connected to the water supply tank through a three-way mixing valve. The first outlet pipe is also connected to the first inlet of the three-way mixing valve, and the water supply tank is connected to the second inlet of the three-way mixing valve. The second heat exchange component includes a second inlet pipe, a second heat exchanger, and a second outlet pipe connected in sequence. The second inlet pipe is connected to the outlet of the three-way mixing valve, and the second outlet pipe is used to connect to the inlet of the boiler body. The flue is connected to the second heat exchanger and the first heat exchanger in sequence, allowing the flue gas to enter the second heat exchanger and the first heat exchanger in sequence, thereby exchanging heat with the water in the second heat exchanger and the first heat exchanger. After the first heat exchanger exchanges heat with the effluent from the air preheater, a three-way mixing valve draws and mixes the effluent from the first heat exchanger with the effluent from the water supply tank, then sends it to the second heat exchanger for further heat exchange before finally entering the boiler body. This multi-stage heat exchange fully utilizes the waste heat from the flue gas to improve heat exchange efficiency and achieve energy savings. The mixing of the effluent from the first heat exchanger with the effluent from the water supply tank before the second heat exchange balances water quality and temperature. Balancing water quality prevents scaling or corrosion, and balancing temperature avoids thermal stress on the system caused by sudden temperature changes, further enhancing system stability and safety.

[0020] This utility model also proposes a boiler flue gas heat exchange system, including a boiler body, an air preheater, a water supply tank, and the aforementioned boiler flue gas heat exchange device, which has high heat exchange efficiency. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the boiler flue gas heat exchange device proposed in this embodiment;

[0022] Figure 2 This is a schematic diagram of the boiler flue gas heat exchange device proposed in this embodiment from another direction.

[0023] In the picture:

[0024] 1. First heat exchange assembly; 11. First inlet pipe; 12. First heat exchanger; 13. First outlet pipe; 2. Second heat exchange assembly; 21. Second inlet pipe; 22. Second heat exchanger; 23. Second outlet pipe; 3. Temperature sensor; 4. First regulating valve; 5. Pressure gauge; 6. Check valve; 7. Second regulating valve; 8. Safety valve; 100. Boiler body. Detailed Implementation

[0025] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, not the entire structure.

[0026] In the description of this utility model, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0027] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0028] In the description of this embodiment, the terms "upper," "lower," "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. In addition, the terms "first" and "second" are only used for distinction in description and have no special meaning.

[0029] Reference Figure 1 and Figure 2 This describes the boiler flue gas heat exchange device in this embodiment.

[0030] This embodiment proposes a boiler flue gas heat exchange device capable of heating the feedwater of an air preheater and a water supply tank. The boiler flue gas heat exchange device includes a first heat exchange component 1 and a second heat exchange component 2 installed on the flue of the boiler body 100. The first heat exchange component 1 includes a first inlet pipe 11, a first heat exchanger 12, and a first outlet pipe 13 connected in sequence. The first inlet pipe 11 is used to connect to the outlet of the air preheater, and the first outlet pipe 13 is connected to the water supply tank through a three-way mixing valve. The water supply tank is connected to the second inlet of the three-way mixing valve. The second heat exchange assembly 2 includes a second inlet pipe 21, a second heat exchanger 22, and a second outlet pipe 23 connected in sequence. The second inlet pipe 21 is connected to the outlet of the three-way mixing valve, and the second outlet pipe 23 is used to connect to the inlet of the boiler body 100. The flue gas is connected to the second heat exchanger 22 and the first heat exchanger 12 in sequence, and can enter the second heat exchanger 22 and the first heat exchanger 12 in sequence to exchange heat with the water in the second heat exchanger 22 and the first heat exchanger 12. After the first heat exchanger 12 exchanges heat with the water outlet of the air preheater, the three-way mixing valve is used to draw out and mix the water outlet of the first heat exchanger 12 with the water outlet of the water supply tank, and send it to the second heat exchanger 22 for heat exchange again, and finally enter the boiler body 100. Multi-stage heat exchange makes full use of the waste heat of the flue gas to improve the heat exchange efficiency and achieve energy saving. In this process, the water outlet of the first heat exchanger 12 is mixed with the water outlet of the water supply tank before undergoing a second heat exchange. This balances the water quality and temperature, preventing scaling or corrosion, and balancing the temperature to avoid thermal stress caused by sudden temperature changes, thereby further improving the stability and safety of the system.

[0031] This boiler flue gas heat exchange device utilizes the principle of stepped heat recovery. Flue gas and water exchange heat counter-currently in the first heat exchange component 1 and the second heat exchange component 2. The flue gas releases heat, and the water absorbs this heat and heats up. Specifically, the flue gas duct is sequentially connected to the second heat exchanger 22 and the first heat exchanger 12. The flue gas can enter the second heat exchanger 22 and the first heat exchanger 12 sequentially for heat exchange. That is, the flue gas temperature in the second heat exchanger 22 is higher than that in the first heat exchanger 12, and the flue gas temperature gradually decreases. Meanwhile, the water flows into the first heat exchanger 12 and the second heat exchanger 22 sequentially for heat exchange, thereby gradually increasing the water temperature and achieving full utilization of energy.

[0032] The air preheater is a key heat exchange device in the industrial boiler system. The outlet water from the air preheater is approximately 70 degrees Celsius, while the water in the supply tank is fresh water to be replenished, at a lower temperature of approximately 30 degrees Celsius. In the first heat exchanger 12, the flue gas heats the water to 100 degrees Celsius, and in the second heat exchanger 22, it heats the water to 130 degrees Celsius before entering the boiler body 100. Simultaneously, the 200-degree Celsius high-temperature flue gas, after passing through the second heat exchanger 22 and the first heat exchanger 12, exits at approximately 100 degrees Celsius. Compared to existing single-stage heat exchangers, the boiler flue gas heat exchange device proposed in this embodiment further fully utilizes the waste heat of the flue gas.

[0033] In the entire heat exchange process, water from the air preheater, which is usually preheated, first enters the first heat exchanger 12 through the first inlet pipe 11. Heat exchange takes place inside the first heat exchanger 12, where the flue gas heats the water to 100 degrees Celsius, resulting in a preheated water flow. The air preheater outlet water, already carrying residual heat, is further heated, reducing the heating load on the boiler's main combustion zone and laying the foundation for subsequent steps. The preheated water then enters the three-way mixing valve through the first outlet pipe 13, simultaneously with water from the supply tank. The preheated water and the water from the supply tank mix, and then the mixture flows from the outlet of the three-way mixing valve into the second heat exchanger. The inlet pipe 21 mixes the initially heated water with the water in the supply tank, balancing the water quality to prevent scaling or corrosion. It also balances the temperature to avoid thermal stress on the system caused by sudden temperature changes. This mixing reduces the heat load on the subsequent second heat exchanger 22, reflecting the "preheat-reheat" stepped design and maximizing heat recovery efficiency. Finally, the mixed water enters the second heat exchanger 22 through the second inlet pipe 21, where it exchanges heat with the higher-temperature flue gas. The higher-temperature flue gas reheats the mixed water to 130 degrees Celsius, reaching a boiling or superheated state to generate steam. Finally, the steam enters the boiler body 100 through the second outlet pipe 23 for industrial use.

[0034] Furthermore, the boiler flue gas heat exchange device also includes temperature sensors 3 for detecting the water temperature in the first inlet pipe 11, the first outlet pipe 13, the second inlet pipe 21, and the second outlet pipe 23. In this embodiment, multiple temperature sensors 3 are installed, located on the first inlet pipe 11, the first outlet pipe 13, the second inlet pipe 21, and the second outlet pipe 23, respectively, to detect the water temperature in multiple pipes. Specifically, detecting the water temperature in the first inlet pipe 11 ensures that the outlet water temperature of the air preheater is normal, laying a good foundation for the entire heat exchange process; detecting the water temperature in the first outlet pipe 13 ensures that the first heat exchange is normal; detecting the water temperature in the second inlet pipe 21 ensures that the water heated initially and the water in the water supply tank have been fully mixed; and detecting the water temperature in the second outlet pipe 23 ensures that the second heat exchange is normal. Multiple temperature sensors 3 work together to provide temperature feedback at multiple stages, preventing the risk of overheating or substandard temperatures in any pipe, and improving work efficiency.

[0035] The boiler flue gas heat exchange device also includes a first regulating valve 4, used to regulate the water flow in the first inlet pipe 11, the first outlet pipe 13, the second inlet pipe 21, and the second outlet pipe 23. In this embodiment, multiple first regulating valves 4 are provided, respectively located on the first inlet pipe 11, the first outlet pipe 13, the second inlet pipe 21, and the second outlet pipe 23, to regulate the water flow in multiple pipes, preventing excessive water flow from causing overload or insufficient water flow from causing low working efficiency. Preferably, the first regulating valve 4 is a shut-off valve.

[0036] Secondly, check valves 6 are installed on the first inlet pipe 11, the first outlet pipe 13, the second inlet pipe 21, and the second outlet pipe 23 to prevent backflow of water in the corresponding pipes, which could cause reverse impact and damage to the boiler flue gas heat exchange device.

[0037] In addition, the boiler flue gas heat exchange device also includes a pressure gauge 5, which is used to detect the water pressure in the first inlet pipe 11, the first outlet pipe 13, the second inlet pipe 21, and the second outlet pipe 23. In this embodiment, multiple pressure gauges 5 are provided, located on the first inlet pipe 11, the first outlet pipe 13, the second inlet pipe 21, and the second outlet pipe 23 respectively, to detect the water pressure in multiple pipes. Specifically, when the water pressure in a certain pipe is too high, the water flow can be adjusted by adjusting the first regulating valve 4 on the corresponding pipe to regulate the water pressure to bring it to the normal range.

[0038] Vents are also provided on the first inlet pipe 11, the first outlet pipe 13, the second inlet pipe 21, and the second outlet pipe 23 to discharge excess air from these pipes. During heat exchange, air may be introduced due to water replenishment from the first inlet pipe 11 or the second inlet pipe 21, or bubbles generated by water turbulence and decomposition gases from water at high temperatures may accumulate in multiple pipes. Therefore, vents are provided on the first inlet pipe 11, the first outlet pipe 13, the second inlet pipe 21, and the second outlet pipe 23 to prevent excessive gas accumulation from threatening work safety.

[0039] Furthermore, safety valves 8 are installed on multiple vents. When venting gas from a water pipe, directly releasing the gas from the vent may be unsafe. Therefore, safety valves 8 are installed to automatically release pressure and enhance safety protection.

[0040] In addition, both the first heat exchanger 12 and the second heat exchanger 22 are equipped with drain ports. When it is necessary to repair the first heat exchanger 12 and the second heat exchanger 22, the water inside the first heat exchanger 12 and the second heat exchanger 22 can be drained through the drain ports. Secondly, when the scale inside the first heat exchanger 12 or the second heat exchanger 22 increases after long-term use, which will lead to a decrease in efficiency, the inside of the first heat exchanger 12 or the second heat exchanger 22 can be chemically cleaned through the drain ports.

[0041] To regulate the water flow rate during drainage of the first heat exchanger 12 and the second heat exchanger 22 and ensure operational safety, a second regulating valve 7 is installed on each of the multiple drain outlets to adjust the water flow rate at the drain outlet. Additionally, the second regulating valve 7 can be used to vent the water from the first heat exchanger 12 and the second heat exchanger 22, improving cleaning and maintenance efficiency. Preferably, the second regulating valve 7 is a venting shut-off valve.

[0042] Furthermore, the first heat exchanger 12 is provided with a flue gas outlet, and the flue gas in the flue is discharged to the outside through the flue gas outlet after heat exchange in the first heat exchanger 12.

[0043] The working process of this boiler flue gas heat exchanger is as follows:

[0044] Water from the air preheater enters the first heat exchanger 12 through the first inlet pipe 11. Inside the first heat exchanger 12, the water comes into contact with the high-temperature flue gas and undergoes heat exchange. The flue gas transfers heat to the water, heating its temperature from the initial value (around 70 degrees) to 100 degrees, resulting in a preheated water flow. Subsequently, the preheated water enters the first outlet pipe 13.

[0045] The three-way mixing valve operates to mix the preheated water in the first outlet pipe 13 with the water in the supply tank. The temperature of the mixed water is between 30 and 100 degrees Celsius (because the preheated water is 100 degrees Celsius, while the water in the supply tank is 30 degrees Celsius). The mixed water enters the second heat exchanger 22 through the second inlet pipe 21. The flue gas temperature in the second heat exchanger 22 is higher. The mixed water exchanges heat with the higher temperature flue gas in the second heat exchanger 22, raising its temperature to 130 degrees Celsius, and finally enters the boiler body 100.

[0046] On the other hand, this embodiment also provides a boiler flue gas heat exchange system, including a boiler body 100, an air preheater, a water supply tank, and the aforementioned boiler flue gas heat exchange device. The air preheater and the water supply tank both provide water flow to the boiler flue gas heat exchange device. The water flow can reach 130 degrees Celsius after passing through the boiler flue gas heat exchange device, and then it is sent to the boiler body 100 for industrial use, resulting in high working efficiency.

[0047] Obviously, the above embodiments of this utility model are merely examples for clearly illustrating the present utility model, and are not intended to limit the implementation of the present utility model. Those skilled in the art can make various obvious changes, readjustments, and substitutions without departing from the protection scope of this utility model. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the protection scope of the claims of this utility model.

Claims

1. A boiler flue gas heat exchanging device, characterized in that, The boiler flue gas heat exchange device is capable of heating the feedwater of the air preheater and the water supply tank. It includes a first heat exchange component (1) and a second heat exchange component (2) installed on the flue of the boiler body (100). The first heat exchange assembly (1) includes a first inlet pipe (11), a first heat exchanger (12), and a first outlet pipe (13) connected in sequence. The first inlet pipe (11) is used to connect to the outlet of the air preheater. The first outlet pipe (13) is connected to the water supply tank through a three-way mixing valve. The first outlet pipe (13) is connected to the first inlet of the three-way mixing valve. The water supply tank can be connected to the second inlet of the three-way mixing valve. The second heat exchange assembly (2) includes a second inlet pipe (21), a second heat exchanger (22), and a second outlet pipe (23) connected in sequence. The second inlet pipe (21) is connected to the outlet of the three-way mixing valve, and the second outlet pipe (23) is used to connect to the inlet of the boiler body (100). The flue is connected to the second heat exchanger (22) and the first heat exchanger (12) in sequence.

2. The boiler flue gas heat exchanging device according to claim 1, characterized in that, The boiler flue gas heat exchange device also includes a temperature sensor (3) for detecting the water temperature in the first water inlet pipe (11), the first water outlet pipe (13), the second water inlet pipe (21), and the second water outlet pipe (23).

3. The boiler flue gas heat exchanging device according to claim 1, characterized in that, The boiler flue gas heat exchange device also includes a first regulating valve (4) for regulating the water flow in the first water inlet pipe (11), the first water outlet pipe (13), the second water inlet pipe (21), and the second water outlet pipe (23).

4. The boiler flue gas heat exchanging device according to claim 1, characterized in that, The boiler flue gas heat exchange device also includes a pressure gauge (5), which is used to detect the water pressure in the first water inlet pipe (11), the first water outlet pipe (13), the second water inlet pipe (21), and the second water outlet pipe (23).

5. The boiler flue gas heat exchanging device according to claim 1, characterized in that, The boiler flue gas heat exchange device also includes a check valve (6), which is used to prevent backflow of water in the first inlet pipe (11), the first outlet pipe (13), the second inlet pipe (21) and the second outlet pipe (23).

6. The boiler flue gas heat exchanging device according to any one of claims 1-5, characterized in that, The first water inlet pipe (11), the first water outlet pipe (13), the second water inlet pipe (21) and the second water outlet pipe (23) are all provided with exhaust ports to discharge excess air from the first water inlet pipe (11), the first water outlet pipe (13), the second water inlet pipe (21) and the second water outlet pipe (23).

7. The boiler flue gas heat exchanging device according to claim 6, characterized in that, Safety valves (8) are provided on each of the aforementioned exhaust ports.

8. The boiler flue gas heat exchanging device according to any one of claims 1-5, characterized in that, Both the first heat exchanger (12) and the second heat exchanger (22) are provided with drain outlets.

9. The boiler flue gas heat exchanging device according to claim 8, characterized in that, Each of the drain outlets is equipped with a second regulating valve (7) for regulating the water flow at the drain outlet.

10. A boiler flue gas heat exchange system, characterized in that, It includes a boiler body (100), an air preheater, a water supply tank, and a boiler flue gas heat exchange device as described in any one of claims 1-9.

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