A boiler total heat recovery device

Abstract

The application provides a boiler total heat recovery device, which comprises a boiler and a waste heat recovery device, wherein the waste heat recovery device comprises six external interfaces, namely a flue gas inlet, a flue gas outlet, an air inlet, an air outlet, a heat network water inlet and a heat network water outlet; air is heated into high-temperature air by the waste heat recovery device and then enters the boiler; high-temperature flue gas discharged from the boiler is discharged after passing through the waste heat recovery device; and heat network return water enters the boiler after passing through the waste heat recovery device. On the basis of total heat exchange of a rotary wheel, the process is appropriately changed to avoid water vapor from entering the inside of the boiler and eliminate the risk of tail flue corrosion. The application utilizes the total heat recovery device to humidify high-temperature flue gas discharged from the boiler body, and realizes the function of heat network return water directly absorbing latent heat of the flue gas.

Description

Technical Field

[0001] This invention relates to the field of waste heat heating technology, and in particular to a boiler total heat recovery device. Background Technology

[0002] Boiler flue gas waste heat recovery is an important measure to reduce energy consumption in heating systems. Conventional boilers have relatively high flue gas temperatures, and waste heat accounts for about 10% of the fuel. Recovering this waste heat can significantly reduce energy consumption.

[0003] The exhaust gas temperature of a gas-fired boiler is typically between 180-200℃. Manufacturers typically add an economizer to lower the exhaust gas temperature to around 80℃ using some of the return water from the heating network. At 80℃, more than 10% of the gas's calorific value can be recovered from the flue gas. Since the return water temperature is around 40-50℃, many users add a condenser at the end of the economizer to further cool the flue gas using all or part of the return water, reducing the temperature to around 50℃. Because the dew point temperature of the gas-fired flue gas is 55-57℃, some flue gas will condense in the condenser, resulting in condensate. Therefore, the exhaust gas temperature of a conventional boiler is generally between 50-80℃ (depending on whether a condenser is installed, the heat exchange area, etc.).

[0004] Heat pump-type flue gas waste heat recovery technology has minimal impact on the original system, requiring only modifications to the tail flue and having no effect on the boiler combustion system. However, absorption heat pumps are expensive, resulting in high overall system costs, while compression heat pumps have high operating costs and relatively high prices.

[0005] The emergence of total heat exchange flue gas waste heat recovery is mainly to eliminate heat pumps and reduce the cost of deep flue gas waste heat recovery. However, due to the increased water vapor content in the exhaust gas, it is prone to corrosion of the heat exchange tubes at the boiler tail end, affecting their service life. Summary of the Invention

[0006] To solve the above-mentioned technical problems, the present invention eliminates equipment such as boiler economizers and directly utilizes the high-temperature flue gas exhaust of the boiler body to regenerate the flue gas total heat recovery device.

[0007] This invention provides a boiler total heat recovery device, comprising: a boiler and a waste heat recovery unit. The waste heat recovery unit includes six external interfaces: a flue gas inlet, a flue gas outlet, an air inlet, an air outlet, a heating network water inlet, and a heating network water outlet. Air is heated to high temperature by the waste heat recovery unit and then introduced into the boiler. The high-temperature flue gas discharged from the boiler is discharged after passing through the waste heat recovery unit, and the heating network return water enters the boiler after passing through the waste heat recovery unit.

[0008] Furthermore, the high-temperature air introduced into the boiler is collected and used to heat the surrounding buildings.

[0009] Furthermore, the waste heat recovery unit includes a rotary total heat exchanger and a flue gas heat exchanger, wherein the rotary total heat exchanger and the flue gas heat exchanger are connected.

[0010] Furthermore, the rotary total heat exchanger includes a regeneration zone, a cooling zone, and a moisture absorption zone. The rotation direction of the rotary total heat exchanger is from the regeneration zone to the cooling zone, then to the moisture absorption zone, and then back to the regeneration zone.

[0011] Furthermore, the flue gas inlet is connected to the flue gas outlet of the boiler body. The high-temperature flue gas discharged from the boiler first enters the regeneration zone, then enters the flue gas heat exchanger. The cooled high-temperature flue gas enters the dehumidification zone and is discharged from the flue gas outlet after dehumidification.

[0012] Furthermore, the air inlet is connected to outdoor air, and the air is heated after passing through the cooling zone, and the high-temperature air enters the boiler.

[0013] Furthermore, the heating network water inlet is connected to the heating network return water pipe, and the heating network return water enters the flue gas heat exchanger to be heated before returning to the heating network return water pipe.

[0014] Furthermore, the waste heat recovery unit also includes an air-water heat exchanger, which is installed at the air outlet. The heat network return water includes two paths, one of which enters the flue gas heat exchanger and the other of which enters the air-water heat exchanger.

[0015] Furthermore, the waste heat recovery unit includes: a rotary total heat exchanger, a spray heat exchanger, and a water-to-water heat exchanger. The rotary total heat exchanger is connected to the spray heat exchanger, and the spray heat exchanger is connected to the water-to-water heat exchanger. After passing through the rotary total heat exchanger, the high-temperature flue gas enters the spray heat exchanger for cooling. The intermediate water is heated and then enters the water-to-water heat exchanger to exchange heat with the heat network return water.

[0016] Furthermore, the waste heat recovery unit also includes an air-water heat exchanger, which is installed at the air outlet. The heat network return water includes two paths, one of which enters the water-to-water heat exchanger and the other of which enters the air-water heat exchanger.

[0017] Compared with the prior art, the beneficial effects of the present invention are: by using a waste heat recovery device, water vapor is prevented from directly entering the boiler, which will not affect the internal environment of the boiler and will not cause internal corrosion of the boiler. Attached Figure Description

[0018] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the boiler total heat recovery device according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of a waste heat recovery device according to an embodiment of the present invention; Figure 3 This is a schematic diagram of another waste heat recovery device according to an embodiment of the present invention; Figure 4 This is a schematic diagram of another waste heat recovery device according to an embodiment of the present invention; Figure 5 This is a schematic diagram of another waste heat recovery device according to an embodiment of the present invention.

[0020] Explanation of reference numerals in the attached figures: 1: Boiler; 2: Waste heat recovery unit; 3: Regeneration zone; 4: Cooling zone; 5: Moisture absorption zone; 6: Flue gas heat exchanger; 7: Spray heat exchanger; 8: Water-to-water heat exchanger; 9: Air-to-water heat exchanger; 11: Air; 12: High-temperature air; 13: High-temperature flue gas; 14: Heat network return water. Detailed Implementation

[0021] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, 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 limiting this invention.

[0023] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. Furthermore, the terms "installed," "connected," and "linked" should be interpreted broadly; for example, they may refer to a fixed connection, a detachable connection, or an integral connection; they may refer to a mechanical connection or an electrical connection; they may refer to a direct connection or an indirect connection through an intermediate medium; and they may refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0024] like Figures 1 to 5 As shown, this invention provides a boiler total heat recovery device, comprising: a boiler 1 and a waste heat recovery unit 2. The waste heat recovery unit 2 includes six external interfaces: a flue gas inlet, a flue gas outlet, an air inlet, an air outlet, a heating network water inlet, and a heating network water outlet. Air 11 is heated to high-temperature air 12 by the waste heat recovery unit 2 and then introduced into the boiler 1. High-temperature flue gas 13 discharged from the boiler 1 is discharged after passing through the waste heat recovery unit 2, and heating network return water 14 enters the boiler 1 after passing through the waste heat recovery unit 2. The high-temperature air 12 introduced into the boiler 1 is collected and used to heat surrounding buildings.

[0025] In some preferred embodiments, the waste heat recovery unit 2 includes a rotary total heat exchanger and a flue gas heat exchanger 6, which are connected together.

[0026] In some preferred embodiments, the rotary total heat exchanger includes a regeneration zone 3, a cooling zone 4, and a moisture absorption zone 5. The rotation direction of the rotary total heat exchanger is from the regeneration zone 3 to the cooling zone 4, then to the moisture absorption zone 5, and then back to the regeneration zone 3.

[0027] In some preferred embodiments, the flue gas inlet is connected to the main flue gas outlet of the boiler 1. The high-temperature flue gas 13 discharged from the boiler 1 first enters the regeneration zone 3, then enters the flue gas heat exchanger 6, and the cooled high-temperature flue gas 13 enters the moisture absorption zone 5. After dehumidification, it is discharged from the flue gas outlet.

[0028] In some preferred embodiments, the flue gas inlet is connected to the main flue gas outlet of the boiler 1. The high-temperature flue gas 13 discharged from the boiler 1 first enters the regeneration zone 3, then enters the flue gas heat exchanger 6, and the cooled high-temperature flue gas 13 enters the moisture absorption zone 5. After dehumidification, it is discharged from the flue gas outlet.

[0029] In some preferred embodiments, the air inlet is connected to outdoor air 11, the air 11 is heated after passing through the cooling zone 4, and the high-temperature air 12 enters the boiler 1.

[0030] In some preferred embodiments, the heating network water inlet is connected to the heating network return water pipe, and the heating network return water 14 enters the flue gas heat exchanger 6 to be heated before returning to the heating network return water pipe.

[0031] The waste heat recovery unit 2 also includes an air-water heat exchanger 9, which is installed at the air outlet. The heat network return water 14 includes two paths, one of which enters the flue gas heat exchanger 6 and the other of which enters the air-water heat exchanger 9.

[0032] In some preferred embodiments, the waste heat recovery unit 2 includes: a rotary total heat exchanger, a spray heat exchanger 7 and a water-to-water heat exchanger 8. The rotary total heat exchanger and the spray heat exchanger 7 are connected, and the spray heat exchanger 7 and the water-to-water heat exchanger 8 are connected. After passing through the rotary total heat exchanger, the high-temperature flue gas enters the spray heat exchanger 7 for cooling. After the intermediate water is heated, it enters the water-to-water heat exchanger 8 and the heat network return water 14 for heat exchange.

[0033] In some preferred embodiments, the waste heat recovery unit 2 also includes an air-to-water heat exchanger 9, which is installed at the air outlet. The heat network return water 14 includes two paths, one of which enters the water-to-water heat exchanger 8 and the other of which enters the air-to-water heat exchanger 9.

[0034] The working principle of this invention is as follows: After absorbing water vapor from the low-temperature flue gas in the moisture absorption zone 5, it is transferred to the regeneration zone 3 and regenerated by the high-temperature superheated flue gas. The high-temperature flue gas 13 cools down, and the absorbed water vapor enters the flue gas, increasing the flue gas dew point temperature. The high-humidity flue gas enters the flue gas heat exchanger 6 and is cooled to saturation by the heating network water, with a temperature of about 50-55℃ (determined by the return water temperature). The saturated flue gas then enters the moisture absorption zone. After being regenerated by the high-temperature flue gas 13 in the regeneration zone 3, the rotor is at a high temperature and does not have the ability to absorb moisture. It then enters the cooling zone 4 and is cooled by the air, forming a low-temperature and low-humidity state. It then enters the moisture absorption zone 5 again, comes into contact with the saturated flue gas, and absorbs water vapor from the flue gas. The flue gas temperature decreases slightly, and the saturation temperature drops to below 30℃. The high-temperature air 12 generated in the cooling zone 4 can be directly introduced into the boiler 1. If the air volume is large, it can also be collected and directly supplied as heating air to the surrounding buildings. To prevent the air temperature from becoming too high and the volume from becoming too large, which would prevent the fan of boiler 1 from drawing in enough combustion air, an air-water heat exchanger 9 can be added to use the heating network water to cool the air and reduce its volume.

[0035] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A boiler total heat recovery device, characterized in that, include: The boiler (1) and the waste heat recovery unit (2) include six external interfaces, namely flue gas inlet, flue gas outlet, air inlet, air outlet, heating network water inlet and heating network water outlet; air (11) is heated into high temperature air (12) by the waste heat recovery unit (2) and then introduced into the boiler (1); the high temperature flue gas (13) discharged from the boiler (1) is discharged after passing through the waste heat recovery unit (2); and the heating network return water (14) enters the boiler (1) after passing through the waste heat recovery unit (2). The high-temperature air (12) introduced into the boiler (1) is collected and used to heat the surrounding buildings; the waste heat recovery unit (2) includes: a rotary total heat exchanger and a flue gas heat exchanger (6), the rotary total heat exchanger and the flue gas heat exchanger (6) are connected, the rotary total heat exchanger includes a regeneration zone (3), a cooling zone (4) and a moisture absorption zone (5), the rotation direction of the rotary total heat exchanger is from the regeneration zone (3) to the cooling zone (4) then to the moisture absorption zone (5) and back to the regeneration zone (3); the flue gas inlet is connected to the main body flue gas of the boiler (1). The high-temperature flue gas (13) discharged from the boiler (1) first enters the regeneration zone (3), then enters the flue gas heat exchanger (6), and the cooled high-temperature flue gas (13) enters the moisture absorption zone (5), and is discharged from the flue gas outlet after being dehumidified; the air inlet is connected to the outdoor air (11), and the air (11) is heated after passing through the cooling zone (4), and the high-temperature air (12) enters the boiler (1); the heat network water inlet is connected to the heat network return water pipe, and the heat network return water (14) enters the flue gas heat exchanger (6) to be heated and then returns to the heat network return water pipe.

2. The boiler total heat recovery device according to claim 1, characterized in that, The waste heat recovery unit (2) also includes an air-water heat exchanger (9), which is installed at the air outlet. The heat network return water (14) includes two paths, one of which enters the flue gas heat exchanger (6) and the other of which enters the air-water heat exchanger (9).

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