A novel flue gas heat recovery spray tower and flue gas waste heat recovery and utilization system

Abstract

This invention relates to the field of waste heat recovery technology, specifically a novel flue gas heat recovery spray tower and flue gas waste heat recovery and utilization system. The system includes a spray tower body, a flue gas inlet, a flue gas outlet, a baffle plate, a water receiving plate, spray pipes, a water supply pipe, a water seal tank, a return water pipe, a booster pump, and a water treatment tank. This invention effectively absorbs the sensible and latent heat in boiler flue gas, reducing the exhaust temperature and improving the boiler's thermal efficiency. The multi-layer spraying system, with its baffle plate preventing water droplets from being discharged with the flue gas, and the upward-sloping arrangement of the water receiving plate and spray pipes, ensures smoother exhaust of hot flue gas and solves the problem of flue gas eddies. Therefore, this novel flue gas heat recovery spray tower has advantages such as high efficiency, reliability, safety, flexibility, energy saving, stability, and long service life.

Description

Technical Field

[0001] This invention relates to the field of waste heat recovery technology, specifically to a novel flue gas heat recovery spray tower and a flue gas waste heat recovery and utilization system. Background Technology

[0002] Traditional natural gas boilers have high flue gas temperatures, generally exceeding 80℃ and often above 90℃. At this temperature, water vapor is in a superheated state, and the latent heat of vaporization of water vapor carried away with the flue gas accounts for about 10% of the lower heating value of natural gas, which is the main cause of flue gas heat loss. Therefore, reducing the boiler's flue gas temperature, thereby recovering and utilizing the sensible heat and some of the latent heat of water vapor in the flue gas, can further improve the boiler's thermal efficiency and has significant energy-saving potential. There are two main ways to reduce flue gas temperature: one is through indirect heat exchangers, and the other is through direct contact heat exchange. Indirect heat exchange is affected by the heat transfer difference at the heat exchanger ends. Using 50℃ heating return water for heat exchange makes it difficult to lower the flue gas temperature below the flue gas dew point. Water vapor in the flue gas cannot condense, resulting in the inability to utilize the latent heat of vaporization of water vapor in the flue gas, leading to poor energy-saving effect. Simply increasing the heat transfer area will increase the metal consumption of the flue gas heat exchanger and the floor space required, thus increasing the initial investment of the equipment. Direct contact spray towers have a simple structure, are easy to manufacture, install, and maintain, and consume less metal. They eliminate heat transfer differences, making them suitable for applications with small temperature differences. Without fouling or wall thermal resistance, they offer high heat exchange efficiency, completing the heat and mass transfer process instantaneously. This can reduce flue gas temperature to 30°C, below the flue gas dew point temperature, allowing for the full recovery of sensible heat, latent heat of water vapor, and condensate from the flue gas. Simultaneously, pollutants in the flue gas are cleaned during the heat exchange process, resulting in cleaner flue gas and contributing to environmental protection. The use of lithium bromide absorption heat pumps can transfer the heat absorbed by the direct contact spray tower to the primary return water, raising the boiler return water temperature, reducing boiler fuel consumption, and improving boiler thermal efficiency.

[0003] Traditional direct contact spray towers include perforated plate bubbling type, packed type, and baffle plate type. Perforated plate bubbling type and packed type spray towers are heavy due to water inside the tower or the installation of packing, making them unsuitable for high-level installation. Traditional baffle plate type spray towers only consider the flowability of spray water and do not consider the flowability of flue gas, which leads to the accumulation of flue gas eddies, which is not conducive to the full mixing of flue gas and spray water, resulting in poor heat exchange effect.

[0004] In view of this, the present invention is hereby proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a novel flue gas heat recovery spray tower and a flue gas waste heat recovery and utilization system to solve the defects of the baffle spray tower mentioned in the background art, such as flue gas eddy, insufficient heat exchange, and large mass. At the same time, this invention can be used for the recovery and utilization of flue gas heat from gas-fired boilers, thereby reducing boiler exhaust temperature, improving boiler thermal efficiency, saving energy, and improving the atmospheric environment.

[0006] To achieve one of the above objectives, the present invention provides the following technical solution:

[0007] A novel flue gas heat recovery spray tower includes a spray tower body, a flue gas inlet, and a flue gas outlet. The spray tower body is also equipped with a top spray pipe, a water receiving plate, and layered spray pipes.

[0008] The top spray pipe is connected to the first outlet of the heat exchanger via a water supply pipe; one end of the water receiving plate and one end of the layered spray pipe are fixed to the inner wall of the spray tower body, and the other end is inclined upwards; the layered spray pipe is connected to the first outlet of the heat exchanger via a water supply pipe; the water receiving plate is connected to the water treatment tank via a return water pipe, and the water treatment tank is connected to the first inlet of the heat exchanger.

[0009] Preferably, the smoke inlet is located below the spray tower body, and the smoke outlet is located above the spray tower body.

[0010] Preferably, a water baffle is provided below the smoke exhaust port.

[0011] Preferably, a water seal tank is installed on the return water pipe, and the water seal tank is located at the outlet of the water receiving plate.

[0012] Preferably, the water seal tank is equipped with a drain valve.

[0013] Preferably, a variable frequency booster pump is installed on the pipeline connecting the water treatment tank and the heat exchanger.

[0014] Preferably, a tower support is also connected below the spray tower body.

[0015] Preferably, the water receiving plate and the layered spray pipe are arranged in multiple layers from top to bottom.

[0016] To achieve the second objective mentioned above, the present invention provides the following technical solution:

[0017] A flue gas waste heat recovery and utilization system includes a novel flue gas heat recovery spray tower as described above.

[0018] Compared with existing technologies, the advantages of this invention are as follows: This novel flue gas heat recovery spray tower can effectively absorb the sensible and latent heat in boiler flue gas, reducing the exhaust temperature and improving the boiler's thermal efficiency; the spray tower employs multi-layer spraying, and the baffle plate can prevent water droplets in the flue gas from being discharged with the flue gas; the tower body adopts a rectangular arrangement, allowing for adjustment of the tower size according to site conditions, making the layout more flexible; the water receiving plate and spray pipes are arranged obliquely upwards, making the hot flue gas discharge smoother and solving the flue gas eddy problem. The spray tower is equipped with a booster pump with frequency conversion control, adjusting the spray pressure according to changes in flue gas volume to ensure thorough mixing of flue gas and spray water, maximizing the absorption of heat from the flue gas; the return water pipe of this spray tower is equipped with a water seal tank, allowing the circulating water, after thorough mixing with the flue gas, to flow by gravity to the water treatment tank after heat exchange through the heat exchanger. Therefore, this novel flue gas heat recovery spray tower has advantages such as high efficiency, reliability, safety, flexibility, energy saving, stability, and long service life.

[0019] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the structure of a novel flue gas heat recovery spray tower provided in an embodiment of the present invention.

[0022] Figure 2 A cross-sectional view of the AA section in a novel flue gas heat recovery spray tower provided in an embodiment of the present invention.

[0023] Figure 3 This is a cross-sectional view of the BB section in a novel flue gas heat recovery spray tower provided in an embodiment of the present invention.

[0024] In the diagram: 1. Smoke exhaust port; 2. Water baffle plate; 3. Top-level spray pipe; 4. Spray tower body; 5. Water receiving plate; 6. Layered spray pipe; 7. Water seal tank; 8. Sewage valve; 9. Water supply pipe; 10. Return water pipe; 11. Smoke inlet; 12. Tower support; 13. Booster pump; 14. Water treatment tank; 15. Heat exchanger. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0026] like Figure 1-3 As shown in the figure, this embodiment of the invention provides a novel flue gas heat recovery spray tower, which consists of a flue gas outlet 1, a water baffle plate 2, a top spray pipe 3, a spray tower body 4, a water receiving plate 5, layered spray pipes 6, a water seal tank 7, a drain valve 8, a water supply pipe 9, a return water pipe 10, a flue gas inlet 11, a tower support 12, a booster pump 13, and a water treatment tank 14. In this novel flue gas heat recovery spray tower, the flue gas inlet 11 and the flue gas outlet 1 are connected to the spray tower body 4. The spray tower is equipped with a water receiving plate 5, a top spray pipe 3, and layered spray pipes 6, which are arranged obliquely upwards. The lower end of the water supply pipe 9 is connected to the outlet of the heat exchanger 15, and the upper end is connected to the top spray pipe 3 and the layered spray pipe 6 respectively. The cooled low-temperature water is pressurized by the booster pump 13 and then transported to the top spray pipe 3 and the layered spray pipe 6 through the heat exchanger 15 via the water supply pipe 9. The pressurized cooling water is evenly sprayed into the spray tower through the nozzles on the top spray pipe 3 and the layered spray pipe 6, so that it is fully mixed with the flue gas. The water seal tank 7 is connected to the water receiving plate 5 inside the spray tower. The pipes after each water seal tank 7 converge into the return water pipe 10 and then into the water treatment tank 14. The cooling water, after being fully mixed with the hot flue gas, is heated and sprayed onto the water receiving plate 5. The water receiving plate 5 is arranged at an angle downwards. The cooling water can flow into the water seal tank 7 by gravity and then flow into the water treatment tank 14 through the return water pipe 10. The function of the water seal tank 7 is to prevent the flue gas inside the spray tower from leaking out.

[0027] In a preferred embodiment of the present invention, a water baffle plate 2 is provided at the lower part of the flue gas outlet 1. The flue gas after being fully mixed with cooling water and cooled contains water mist. The water baffle plate 2 can block most of the water mist inside the spray tower body 4. The water mist condenses into water droplets and drips onto the water receiving plate 5. Together with the spray water, it flows into the water treatment tank 14 through the water seal tank 7 and the return water pipe 10. The water seal tank is equipped with a drain valve 8, which can discharge impurities mixed with water in the flue gas.

[0028] In addition, embodiments of the present invention also provide a flue gas waste heat recovery and utilization system, comprising a novel flue gas heat recovery spray tower, which consists of a flue gas outlet 1, a water baffle plate 2, a top spray pipe 3, a spray tower body 4, a water receiving plate 5, layered spray pipes 6, a water seal tank 7, a drain valve 8, a water supply pipe 9, a return water pipe 10, a flue gas inlet 11, a tower support 12, a booster pump 13, and a water treatment tank 14.

[0029] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use. They are 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, and therefore should not be construed as a limitation of this invention. In addition, the terms "first," "second," "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0030] Furthermore, terms such as "horizontal," "vertical," and "sag" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0031] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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; and they can 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.

[0032] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the scope of protection of the invention. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

Claims

1. A novel flue gas heat recovery spray tower comprising a spray tower body, a flue gas inlet, a flue gas outlet, characterized in that, A top layer spray pipe, a water collecting plate and a layered spray pipe are arranged in the spray tower body. The top layer spray pipe is connected with the first water outlet of the heat exchanger through a water supply pipe; the water collecting plate and one end of the layered spray pipe are fixed on the inner wall of the spray tower body, and the other end of them is arranged upwardly; the layered spray pipe is connected with the first water outlet of the heat exchanger through a water supply pipe; the water collecting plate is communicated with the water treatment pool through a backwater pipe; the water treatment pool is communicated with the first water inlet of the heat exchanger.

2. A novel spray tower for heat recovery from flue gases as claimed in claim 1 wherein, The smoke inlet is located below the spray tower body, and the smoke outlet is located above the spray tower body.

3. A novel heat recovery spray tower for flue gases according to claim 2, characterized in that, A water baffle is arranged below the smoke outlet.

4. A novel heat recovery spray tower for flue gases according to claim 3, characterized in that, A water seal tank is arranged on the backwater pipe, and the water seal tank is located at the water outlet of the water collecting plate.

5. A novel heat recovery spray tower for flue gases according to claim 4, characterized in that, A blowdown valve is arranged in the water seal tank.

6. A novel heat recovery spray tower for flue gases according to claim 5, characterized in that, A variable frequency pressurizing pump is arranged on the pipeline communicated with the heat exchanger.

7. A novel heat recovery spray tower for flue gases according to claim 6, characterized in that, A tower body support is further connected below the spray tower body.

8. A novel heat recovery spray tower for flue gases according to claim 7, characterized in that, The water collecting plate and the layered spray pipe are arranged in multiple layers from top to bottom.

9. A flue gas waste heat recovery system characterized by, A novel flue gas heat recovery spray tower comprising the spray tower according to any one of claims 1-8.

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