A wet flue gas waste heat deep recovery system
Patent Information
- Application Number
- CN202522359479.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-06
- Publication Date
- 2026-10-27
- Estimated Expiration
- 2035-11-06
AI Technical Summary
[0002]现有燃煤/燃气/生物质锅炉经石灰石-石膏湿法脱硫后，烟气温度通常维持在40–55℃，其中水蒸气携带的显热（约50–80 kJ/m³）及汽化潜热（约1500–2000 kJ/m³）未被有效利用，导致能源浪费率达20%以上
1、本实用新型通过烟道式换热技术实现40–55℃低温烟气的显热、潜热及水蒸气回用，在饱和温度下的烟气中水蒸汽潜热利用至20℃～30℃，实现烟气余热能量的深度回收，烟气中水蒸气体积分数可达1.5%～3%，从而起到“消白”作用，而取代烟气加热“消白”的工艺。
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Figure CN224904983U_ABST
Abstract
Description
Technical Field
[0001] The present utility model relates to the technical field of waste heat recovery, and specifically relates to a deep waste heat recovery system for wet flue gas after limestone-gypsum wet desulfurization. Background Art
[0002] After the existing coal-fired / gas-fired / biomass-fired boilers undergo limestone-gypsum wet desulfurization, the flue gas temperature is usually maintained at 40–55°C, and the sensible heat (about 50–80 kJ / m³) and vaporization latent heat (about 1500–2000 kJ / m³) carried by the water vapor are not effectively utilized, resulting in an energy waste rate of over 20%. Traditional flue gas waste heat recovery systems (such as shell-and-tube heat exchangers) require additional auxiliary facilities such as cooling towers, which occupy a large area, and have problems such as increased flue gas resistance, easy condensation and corrosion, making them difficult to implement in small and medium-sized boilers or plants with limited space. Contents of the Utility Model
[0003] The present utility model overcomes the deficiencies of the prior art, and proposes a deep waste heat recovery system for wet flue gas; it is especially suitable for limestone-gypsum wet desulfurization devices supporting coal-fired / gas-fired / biomass-fired boilers, and realizes efficient recovery of sensible heat and latent heat of low-temperature flue gas below 55°C through flue duct type heat exchange technology, solving the problems of traditional waste heat recovery systems such as large floor space, difficulty in adapting to plant layout, increased flue gas resistance, and easy condensation and corrosion.
[0004] In order to achieve the above purpose, the present utility model is realized through the following technical solution: A deep waste heat recovery system for wet flue gas includes a flue gas system, an outer circulating water system and an inner circulating water system; the flue gas system includes a wet desulfurization tower, a first clean flue duct, and a flue duct spraying device, the flue duct spraying device is arranged in the first clean flue duct, and the wet desulfurization tower is connected with the first clean flue duct; the outer circulating water system includes a cold source end, a water-water heat exchanger and a heat user which are connected to each other; the inner circulating water system includes a liquid collection device; high-temperature water generated after spraying by the flue duct spraying device is connected with the liquid collection device through a liquid collection pipeline, the liquid collection device is connected with the heat source end of the water-water heat exchanger through a recovered water pipeline, and the low-temperature water outlet of the water-water heat exchanger is connected with the flue duct spraying device.
[0005] Further, the first clean flue duct is connected with a second clean flue duct, and the second clean flue duct is connected with a chimney.
[0006] Further, the cold source end is connected with the water-water heat exchanger through a first water pipeline, and the water-water heat exchanger is connected with the heat user through a second water pipeline.
[0007] Further, the heat user enters the cold source end through a third water pipeline.
[0008] Further, the cold source end is a heat pump or a cooling system of cooling tower equipment.
[0009] Further, the internal circulation water system further comprises water treatment equipment, and the low-temperature water outlet of the water-water heat exchanger is connected to the water treatment equipment through a low-temperature water pipeline.
[0010] Further, part of the recovered water that has completed heat exchange before entering the water treatment equipment enters the flue gas spraying equipment through the spraying water pipeline for recycling.
[0011] Further, the liquid collection device is a box or tank with anti-corrosion properties.
[0012] The beneficial effects of the present utility model compared with the prior art are as follows: 1. The present utility model realizes the sensible heat, latent heat and water vapor reuse of low-temperature flue gas at 40–55°C through flue gas type heat exchange technology, the latent heat of water vapor in the flue gas at saturation temperature is utilized down to 20°C to 30°C, so as to realize deep recovery of flue gas waste heat energy, and the volume fraction of water vapor in the flue gas can reach 1.5% to 3%, thereby achieving the "white plume elimination" effect and replacing the traditional flue gas heating "white plume elimination" process.
[0013] 2. The present utility model solves the technical problems of the traditional waste heat recovery system, such as large floor area and inability to adapt to the renovation requirements of existing plants, and at the same time supports cascade linkage with the waste heat recovery device before desulfurization. Thereby, the waste of secondary energy heat in the plant is maximally reduced, the conversion of primary energy is saved and carbon emissions are reduced, and meanwhile the water vapor in the flue gas is collaboratively collected for reuse to greatly reduce water resource consumption; it is especially suitable for flue gas waste heat recovery after the limestone-gypsum wet desulfurization process supporting coal-fired / gas-fired / biomass boilers. Brief Description of the Drawings
[0014] Figure 1 is a schematic diagram of the connection and process flow of the wet flue gas waste heat deep recovery system according to the present utility model; In the figures: 1. Wet desulfurization tower; 2. First clean flue; 3. Flue gas spraying equipment; 4. Second clean flue; 5. Chimney; 6. Liquid collection pipeline; 7. Liquid collection device; 8. Recovered water pipeline; 9. Water-water heat exchanger; 10. Low-temperature water pipeline; 11. Spraying water pipeline; 12. Cold source end; 13. First water pipeline; 14. Second water pipeline; 15. Heat user; 16. Third water pipeline; 17. Water treatment equipment. Detailed Description of the Embodiments
[0015] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present utility model clearer, the present utility model will be further described in detail with reference to the embodiments and the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present utility model, and are not intended to limit the present utility model. The technical solution of the present utility model will be described in detail below with reference to the embodiments and the accompanying drawings, but the protection scope thereof is not limited thereby.
[0016] See Figure 1 This embodiment proposes a deep recovery system for waste heat from wet flue gas after limestone-gypsum wet desulfurization, including a flue gas system, an external circulating water system, and an internal circulating water system; The flue gas system includes a wet desulfurization tower 1, a first clean flue duct 2, a flue spraying device 3, a second clean flue duct 4, and a chimney 5. The flue spraying device 3 is installed inside the first clean flue duct 2. The wet desulfurization tower 1 is connected to the first clean flue duct 2, the first clean flue duct 2 is connected to the second clean flue duct 4, and the second clean flue duct 4 is connected to the chimney 5. For the low-temperature flue gas at the outlet of the wet desulfurization tower 1, which is about 40℃ to 55℃, the temperature of the flue gas discharged from the wet desulfurization tower 1 is reduced to about 20℃ to 30℃ by passing through the first clean flue duct 2 and the flue spraying device 3 installed inside it. Then, this part of the flue gas is discharged into the chimney 5 through the second clean flue duct 4 for emission.
[0017] The external circulating water system includes a cold source end 12, a water-to-water heat exchanger 9, and a heat user 15. The cold source end 12 is connected to the water-to-water heat exchanger 9 through a first water pipe 13, the water-to-water heat exchanger 9 is connected to the heat user 15 through a second water pipe 14, and the heat user 15 enters the cold source end 12 through a third water pipe 16. The low-temperature water source 15℃~25℃ of the cold source end 12 is connected to the water-to-water heat exchanger 9 through the first water pipe 13 to raise the water temperature to about 40℃~50℃ (selected as needed). The heated water is connected to the heat user 15 through the second water pipe 14 (which can be for heating or other low-temperature heat users). After the heat is used up, the heat user 15 enters the cold source end 12 through the third water pipe 16 for circulation. The cold source end 12 can be a heat pump or cooling tower equipment cooling system. The internal circulating water system includes a liquid collection device 7 and a water treatment device 17. The high-temperature water generated after spraying by the flue spray equipment 3 is connected to the liquid collection device 7 through the liquid collection pipe 6. The high-temperature water enters the liquid collection device 7 and is collected. The liquid collection device 7 is connected to the heat source end of the water-to-water heat exchanger 9 through the recovery water pipe 8. The low-temperature water after heat exchange in the water-to-water heat exchanger 9 enters the water treatment device 17 through the low-temperature water pipe 10 for water purification and reuse. The recovery water before entering the water treatment device 17 after heat exchange enters the flue spray equipment 3 through the spray water pipe 11 for recycling.
[0018] Specifically, the flue gas spraying equipment 3 directly exchanges heat with the wet flue gas from the wet desulfurization tower 1, thereby absorbing the latent heat and sensible heat in the wet flue gas on the one hand, and extracting water from the wet flue gas on the other hand. This part of high-temperature water enters the liquid collection device 7 through the liquid collection pipe 6. The liquid collection device 7 can be a box or tank with anti-corrosion properties. The liquid collection device 7 is connected to the water-water heat exchanger 9 through the recovery water pipe 8. The high-temperature water enters the heat source end of the water-water heat exchanger 9 and exchanges heat with the low-temperature water source that enters the water-water heat exchanger 9 through the cold source end 12. After heat exchange, the collected liquid enters the water treatment equipment 17 for purified water reuse. The recovered water that has undergone heat exchange before entering the water treatment equipment 17 enters the flue gas spraying equipment 3 through the spray water pipe 11 to spray and cool the flue gas for recycling.
[0019] This embodiment proposes a deep waste heat recovery system for wet flue gas, applicable to the utilization of waste heat and water vapor resources in the low-temperature, high-humidity flue gas after limestone-gypsum wet desulfurization tower 1 in the flue gas purification process of coal-fired / gas-fired / biomass boilers. The exhaust temperature of wet desulfurization tower 1 is approximately 40℃~55℃, and the volume fraction of water vapor in the flue gas can reach 10%~15%, containing a large amount of latent heat (approximately 1500–2000 kJ / m³). The high humidity of the flue gas is a prerequisite for its full utilization.
[0020] The deep heat recovery system for flue gas can utilize the low-grade heat of high-humidity flue gas at 40℃~55℃, and the latent heat of water vapor in the flue gas at saturation temperature to 20℃~30℃, thus achieving deep recovery of flue gas waste heat energy. The volume fraction of water vapor in the flue gas can reach 1.5%~3%, thereby playing a role in "whitening" and replacing the flue gas heating "whitening" process.
[0021] The flue gas spray system 3 is the main equipment for achieving deep energy recovery from flue gas. It can be installed in the first clean flue gas duct 2 with almost no additional floor space. It uses a direct heat exchange method to transfer the heat of the flue gas to the recovered water, causing the saturated water vapor in the flue gas to precipitate due to the temperature reduction. At the same time as the water vapor is precipitated, it carries pollutants from the flue gas into the precipitated liquid. It is connected to the liquid collection device 7 through the liquid collection pipe 6. It is not affected by the limited space of the wet desulfurization tower 1. The liquid collection device 7 can be flexibly arranged nearby. The liquid collection device 7 is connected to the water-water heat exchanger 9 through the recovered water pipe 8 for heat exchange. Since a large amount of water and pollutants are precipitated from the flue gas, the collected liquid after heat exchange enters the water treatment equipment 17 for water purification and reuse. The recovered water that has undergone heat exchange before entering the water treatment equipment 17 enters the flue gas spray system 3 through the spray water pipe 11 to spray and cool the flue gas for recycling, thereby completing the recovery and reuse of the working fluid in the flue gas and reducing the consumption of fresh water. The flue gas spray system 3 can be directly installed in existing flues or considered in conjunction with the construction of new flues. It features flue corrosion protection, internal spraying equipment, and can recover heat and working fluid when the system is in operation. When the system is not in operation, it has almost no impact on the resistance of the existing flue gas system. Compared to tower-type equipment, which is limited by space constraints, its implementation feasibility is relatively high.
[0022] The cold source end 12 is the main link providing the cooling water required for direct heat exchange. The cold end can be a heat pump, cooling tower equipment, or cooling system to ensure that the external circulation system can provide sufficient cooling capacity. It is usually integrated with the heat user 15 for comprehensive regulation. The heat user 15 can be a heating user or an industrial system user requiring hot water. The final exhaust temperature of the flue gas is reduced by 20℃ to 30℃, depending on the temperature of the cooling water provided by the cold source end 12. The low-temperature water source provided by the cold source end 12 is 15℃ to 25℃ and is connected to the water-to-water heat exchanger 9 through the first water pipe 13, thereby achieving the separation of the media of the internal circulation water system and the external circulation water system to avoid mutual contamination of the water. The water temperature is raised to about 40℃ to 50℃ (selected as needed), and the heated water is connected to the heat user 15 (which can be a heating user or an industrial system user requiring hot water) through the second water pipe 14. After the heat is used up, the heat user 15 enters the cold source end 12 for circulation through the third water pipe 16, thereby completing the heat utilization of the waste heat of the flue gas.
[0023] The above description is a further detailed explanation of the present invention in conjunction with specific preferred embodiments. It should not be considered that the specific embodiments of the present invention are limited to this. For those skilled in the art, several simple deductions or substitutions can be made without departing from the present invention, and all such deductions or substitutions should be considered to fall within the scope of patent protection determined by the submitted claims.
Claims
1. A deep waste heat recovery system for wet flue gas, characterized in that, It includes a flue gas system, an external circulating water system and an internal circulating water system; the flue gas system includes a wet desulfurization tower (1), a first clean flue (2) and a flue spraying device (3), the flue spraying device (3) is set in the first clean flue (2), and the wet desulfurization tower (1) is connected to the first clean flue (2); the external circulating water system includes a connected cold source end (12) and a water-to-water heat exchanger (9); the internal circulating water system includes a liquid collection device (7); the high-temperature water generated after the flue spraying device (3) sprays is connected to the liquid collection device (7) through the liquid collection pipe (6), the liquid collection device (7) is connected to the heat source end of the water-to-water heat exchanger (9) through the recovery water pipe (8), and the low-temperature water outlet of the water-to-water heat exchanger (9) is connected to the flue spraying device (3).
2. The wet flue gas waste heat deep recovery system according to claim 1, characterized in that, The first clean flue (2) is connected to the second clean flue (4), and the second clean flue (4) is connected to the chimney (5).
3. The wet flue gas waste heat deep recovery system according to claim 1, characterized in that, The cold source end (12) is connected to the water-to-water heat exchanger (9) through the first water pipe (13), and the water-to-water heat exchanger (9) is connected to the heat user (15) through the second water pipe (14).
4. The wet flue gas waste heat deep recovery system according to claim 3, characterized in that, The heat user (15) enters the cold source end (12) through the third water pipe (16).
5. The wet flue gas waste heat deep recovery system according to claim 4, characterized in that, The cold source end (12) is a heat pump or cooling tower equipment cooling system.
6. The wet flue gas waste heat deep recovery system according to claim 1, characterized in that, The internal circulating water system also includes a water treatment device (17), and the low-temperature water outlet of the water-to-water heat exchanger (9) is connected to the water treatment device (17) through a low-temperature water pipe (10).
7. The wet flue gas waste heat deep recovery system according to claim 6, characterized in that, The recycled water that has undergone heat exchange in the front part of the water treatment equipment (17) enters the flue spray equipment (3) through the spray water pipe (11) for recycling.
8. The wet flue gas waste heat deep recovery system according to claim 1, characterized in that, The liquid collection device (7) is a box or tank with anti-corrosion properties.