Low-energy consumption flue gas water-saving system and working method thereof

Abstract

The application discloses a low-energy-consumption flue gas water-saving system and a working method thereof and belongs to the technical field of flue gas water-saving. The low-energy-consumption flue gas water-saving system comprises a first air blowing device, a flue gas four-way valve, a condensing device, a second air blowing device, a flue gas three-way valve, a blowdown three-way valve, a first closed water collecting device, a cold storage device, a second closed water collecting device, a gas-liquid separation device, a rotary heat exchange device, a flue gas charging device and an air three-way valve. The condensing device and the rotary heat exchange device are adopted, heat exchange is fully utilized, the investment cost and the operation and maintenance cost of equipment are saved, the consumption of refrigeration energy caused by high supercooling degree for increasing the condensation water volume is avoided, and the condensation water volume is greatly increased. The condensing device can be used as an air cooling device to store cold energy of phase change material in winter, can reserve cold sources in summer, can blow off dust left by flue gas, and avoids the accumulation of dirt thermal resistance of a pipe wall caused by long-time operation.

Description

A low-energy flue gas water-saving system and its working method Technical Field

[0001] This invention belongs to the field of flue gas water-saving technology, specifically relating to a low-energy flue gas water-saving system and its working method. Background Technology

[0002] The latent heat in saturated, moist flue gas is substantial, and recovering moisture from it requires significant cooling resources. The subcooling of the flue gas and the heat exchanger greatly affects moisture recovery. Generally, the subcooling of the demineralized water and the flue gas is not very high, making it difficult to achieve both high moisture recovery rates and low energy consumption. Furthermore, the low quality of the waste heat from the flue gas makes it difficult to utilize directly. Flue gas also causes ash accumulation and corrosion in the heat exchanger. Dust, as a major thermal resistance, significantly impacts heat exchange. While corrosion-resistant polymer materials offer high flexibility and can prevent ash accumulation, their low thermal conductivity results in poor heat exchange performance.

[0003] The existing water-saving devices have the following problems: dust tends to accumulate in the heat exchanger after long-term operation; the cold source is generally provided by cooling demineralized water, resulting in low subcooling, poor water collection, and the waste heat cannot be directly utilized. Summary of the Invention

[0004] To address the aforementioned problems, the present invention aims to provide a low-energy flue gas water-saving system and its operating method, which significantly increases the amount of condensate while saving energy and power consumption.

[0005] This invention is achieved through the following technical solution:

[0006] This invention discloses a low-energy flue gas water-saving system, including a first blower, a flue gas four-way valve, a condensation device, a second blower, a flue gas three-way valve, a sewage three-way valve, a first closed water collection device, a cold storage device, a second closed water collection device, a gas-liquid separation device, a rotary heat exchanger, a flue gas charging device, and an air three-way valve.

[0007] The rotary heat exchanger includes an outer shell and a flue gas passage, a flue gas-side rotor, a thermally conductive bearing, an air passage, and an air-side rotor disposed within the outer shell. The flue gas-side rotor is fitted outside the flue gas passage, and the air-side rotor is fitted outside the air passage. A power-carrying wire is provided inside the flue gas passage, and the power-carrying wire is connected to a power source. The flue gas-side rotor and the air-side rotor are respectively connected to the thermally conductive bearing, and the thermally conductive bearing is connected to the power source through a rotating shaft.

[0008] The flue gas four-way valve is connected to the flue gas inlet and flue gas passage of the desulfurization tower, the first blower, and the condenser, respectively; the flue gas three-way valve is connected to the flue gas outlet of the condenser, the flue gas passage, and the atmospheric environment, respectively; the flue gas charging device is located at the inlet of the flue gas passage; the inlet and outlet of the cooling circulating medium of the condenser are connected to the cold storage device through pipelines, respectively; the lower part of the condenser is connected to the first closed water collection device and the sewage pipe through the drain three-way valve, respectively; the outlet of the flue gas passage is connected to the inlet of the gas-liquid separator, the liquid outlet of the gas-liquid separator is connected to the second closed water collection device, and the gas outlet of the gas-liquid separator is connected to the chimney; the inlet of the air passage is connected to the second blower; the air three-way valve is connected to the outlet of the air passage, the fresh air system, and the atmospheric environment, respectively.

[0009] Preferably, the cold storage device includes an insulating shell filled with an organic composite phase change material, and a cooling medium circulation pipe is meandering within the organic composite phase change material. The cooling medium circulation pipe is connected to the inlet and outlet of the condensation device.

[0010] Preferably, the gas-liquid separation device is Y-shaped, with the upper end of the straight pipe section serving as the inlet, the lower end of the straight pipe section connecting to the liquid outlet, and the inclined pipe section connecting to the gas outlet; a demister is installed inside the liquid outlet, and a vibrating wire grid is installed inside the inclined pipe section; the demister is connected to positive power, and the vibrating wire grid is grounded.

[0011] More preferably, the upper part of the straight pipe section is provided with a one-way valve for flue gas backflow.

[0012] More preferably, the defogging device is a baffle plate type, a ridge type, or a tubular type.

[0013] Preferably, the condenser is a tube bundle type, fin type or plate type, and the surface of the heat exchange component is provided with a hydrophobic layer.

[0014] Preferably, both the flue gas side rotor and the air side rotor are stainless steel hollow cylindrical structures with several radially arranged heat transfer plates inside; the outer shell is sealed, with the outer shell on the side where the flue gas side rotor is located made of infrared transmitting material and the outer shell on the side where the air side rotor is located made of opaque material.

[0015] Preferably, the heat exchange components of the condensation device are made of 1Cr18Ni9Ti, 2205 duplex stainless steel, or modified fluoroplastics.

[0016] The working method of the low-energy flue gas water-saving system disclosed in this invention includes:

[0017] In winter, flue gas from the desulfurization tower enters the flue gas passage through the four-way flue gas valve and the flue gas charging device. The flue gas is charged at the flue gas charging device, and charged particles and charged droplets in the flue gas move towards the pipe wall under the Lorentz force of the magnetic field formed by the current-carrying wire. Ambient air enters the air passage through the second blower. The flue gas side rotor and the air side rotor rotate and exchange heat through the heat-conducting bearing. The flue gas in the flue gas passage exchanges heat with the ambient temperature through radiation and indirectly with the air in the air passage through the flue gas side rotor, and then enters the gas-liquid separation device. The separated condensate enters the second closed water collection device, and the flue gas enters the chimney. The air in the air passage enters the fresh air system through the three-way air valve. The first blower sends the ambient air sprayed with rust remover into the condensation device, which removes dust and rust inside the condensation device and exchanges heat with the cooling circulating medium from the cold storage device. The cold storage device stores cold, and the wastewater generated is discharged through the drain pipe. The air is discharged into the atmosphere through the three-way flue gas valve.

[0018] In summer, the humid flue gas from the desulfurization tower enters the condensation unit and exchanges heat with the cooling circulating medium from the cold storage unit. The resulting condensate enters the first closed water collection device through the drain three-way valve. After heat exchange, the flue gas enters the flue gas passage through the flue gas three-way valve and the flue gas charging device. Ambient air enters the air passage through the second blower. After heat exchange in the rotary heat exchanger, the air in the air passage is discharged into the atmosphere through the air three-way valve. The flue gas in the flue gas passage enters the gas-liquid separation device. The separated condensate enters the second closed water collection device, and the flue gas enters the chimney.

[0019] Preferably, in summer, when the flue gas temperature at the gas outlet of the gas-liquid separator is lower than the ambient air temperature, the air in the air channel enters the fresh air system through the air three-way valve.

[0020] Compared with the prior art, the present invention has the following beneficial technical effects:

[0021] This invention discloses a low-energy flue gas water-saving system that utilizes a condensation device and a rotary heat exchanger. It fully leverages the environment for heat exchange, saving on equipment investment and operation / maintenance costs. It avoids the energy consumption of high subcooling required to increase condensate flow, which is superior to existing technologies that increase the flue gas temperature of the desulfurization tower to increase the subcooling of the flue gas and heat exchanger surface. However, increasing the flue gas temperature leads to more desulfurization slurry being carried away by the flue gas, increasing the amount of condensate flow. But because the water vapor mass fraction of the flue gas at the condensation device inlet increases, the increase in water recovery is small, and a large amount of condensate needs to be processed, with a significant proportion needing to be replenished to the desulfurization tower. The rotary heat exchanger fully utilizes environmental radiation and thermal conductivity with air. The rotor design greatly increases the heat exchange area with air within the same volume. The rotation design allows for full radiative heat exchange between the rotor and the environment, and the increased temperature difference between the rotor and the heat-conducting bearing enhances thermal conductivity. Indirect heat exchange occurs between rotors via thermally conductive bearings. This indirect heat exchange allows uncontaminated air to be utilized by the fresh air system for cooling in summer and heating in winter. The energized wires within the flue gas duct create a magnetic field. Positively charged particles and small droplets move towards the duct wall under the influence of the Lorentz force. This enhances the capture of particles in the flue gas. Furthermore, the non-condensable gas layer is the main factor affecting heat exchange in humid flue gas. Under the influence of the energized wires, small droplets and particles, driven by the Lorentz force, penetrate the non-condensable gas layer to reach the liquid film or wall surface, further enhancing heat exchange and significantly increasing condensate flow.

[0022] Furthermore, in recent years, indirect condensation and water collection materials have mostly adopted corrosion-resistant polymers such as fluoroplastics. This is because flue gas condensation carries particulate matter, ash accumulation, and low-temperature corrosion problems. However, due to material and process limitations, the thermal conductivity of mainstream fluoroplastic heat exchanger materials on the market is relatively low, ranging from 0.2 to 0.3 W / (m·K). Although material modification has significantly improved the heat transfer coefficient, with some studies achieving a thermal conductivity of up to 20 W / (m·K), it has not been maturely applied to heat exchanger manufacturing due to cost and process constraints. Metal materials have high thermal conductivity, resulting in large heat transfer coefficients for metal heat exchangers, and are inexpensive with low investment costs. However, they generally suffer from ash accumulation and low-temperature corrosion problems. The condensation device of this invention can act as an air-cooling device in winter to store cold for the phase change material, providing a cold source for summer. It can also purge dust left by flue gas, preventing the accumulation of fouling and thermal resistance on the pipe walls during long-term operation. Therefore, using a metal heat exchanger can improve the heat transfer coefficient and reduce investment costs.

[0023] Furthermore, the cold storage device utilizes organic composite phase change materials, which absorb or release heat during phase change to store or release energy. This results in high energy density, a simple device, and a small size. The organic composite phase change materials chosen have phase change temperatures primarily between -10 and 20°C, meeting the requirements of northern winter environments. The insulating outer shell provides thermal insulation.

[0024] Furthermore, the gas-liquid separation device adopts a Y-type design. Liquid droplets and films are collected by the second closed-loop water collection device through inertia and the interception effect of the demister. The demister is positively charged, repelling charged droplets and particulate matter. The vibrating wire grid is grounded, capturing small charged droplets entering the second closed-loop water collection device and preventing them from being carried away by the drag force of the flue gas. After prolonged operation, the internal gas pressure of the second closed-loop water collection device increases. Since the total pressure equals the static pressure plus the dynamic pressure, when the static pressure inside the second closed-loop water collection device increases, the flue gas will not flow inward but will instead pass through the demister and be discharged through the chimney.

[0025] Furthermore, a one-way valve for flue gas backflow is installed at the top of the straight pipe section to prevent flue gas backflow.

[0026] Furthermore, both the flue gas-side rotor and the air-side rotor are stainless steel hollow cylindrical structures with several radially arranged heat transfer plates inside. This increases the radiative heat transfer area. At the same rotational speed, a larger rotor outer diameter results in a faster circumferential linear velocity, leading to a greater temperature difference between the high-speed rotor and the heat-conducting bearing, thus improving heat conduction. The outer shell is sealed to prevent particulate matter from entering the rotor and causing wear. The outer shell on the flue gas-side rotor side is made of an infrared-transmitting material, which facilitates radiative heat exchange with the outside environment; the outer shell on the air-side rotor side is made of an opaque material, which helps with heat and cold insulation.

[0027] The operating method of the low-energy flue gas water-saving system disclosed in this invention utilizes a rotary heat exchanger to condense moisture in the humid flue gas during low winter temperatures. The traditional condenser is used as an air-cooled device to cool the circulating medium and store cold for the cold storage device. Simultaneously, ambient air sprayed with rust remover cleans and removes rust from the surface of the condenser, ensuring that the heat transfer coefficient does not significantly decrease due to ash accumulation after prolonged operation. In summer, through heat exchange with the cold storage material, the moisture collected in the condensed flue gas undergoes a secondary heat exchange in the rotary heat exchanger, further recovering moisture from the flue gas. Attached Figure Description

[0028] Figure 1 is a schematic diagram of the overall system structure of the present invention;

[0029] Figure 2 is a schematic diagram of the rotary heat exchanger.

[0030] Figure 3 is a schematic diagram showing the direction of the Lorentz force on charged particles and charged droplets;

[0031] Figure 4 is a schematic diagram of the flue gas charging device;

[0032] Figure 5 is a schematic diagram of the Y-shaped water collection structure;

[0033] Figure 6 is a flowchart of the operation of the condensation device of the system of the present invention in winter;

[0034] Figure 7 is a flowchart of the operation of the rotary air-cooling device of the system of the present invention in winter;

[0035] Figure 8 is a water-saving flowchart of the system of the present invention in summer;

[0036] Figure 9 shows the experimental data and predicted values ​​of flue gas temperature decrease after using the system of the present invention.

[0037] In the diagram: 1. Desulfurization tower; 2. First blower; 3. Flue gas four-way valve; 4. Condensation device; 5. Second blower; 6. Flue gas three-way valve; 7. Sewage discharge three-way valve; 8. First closed water collection device; 9. Cold storage device; 10. Second closed water collection device; 11. Vibrating wire grid; 12. Gas-liquid separator; 13. Rotary heat exchanger; 14. Flue gas passage; 15. Flue gas side rotor; 16. Thermally conductive bearing; 17. Air passage; 18. Air side rotor; 19. Shell; 20. Power supply; 21. Power-carrying wire; 22. Flue gas charging device; 23. Air three-way valve; 24. Fresh air system; 25. Chimney. Detailed Implementation

[0038] The present invention will now be described in further detail with reference to the accompanying drawings. This description is intended to explain the invention and not to limit it.

[0039] Figure 1 shows the low-energy flue gas water-saving system of the present invention, which includes a first blower 2, a flue gas four-way valve 3, a condensation device 4, a second blower 5, a flue gas three-way valve 6, a sewage discharge three-way valve 7, a first closed water collection device 8, a cold storage device 9, a second closed water collection device 10, a gas-liquid separation device 12, a rotary heat exchange device 13, a flue gas charging device 22, and an air three-way valve 23.

[0040] As shown in Figure 2, the rotary heat exchanger 13 includes a housing 19 and a flue gas passage 14, a flue gas-side rotor 15, a thermally conductive bearing 16, an air passage 17, and an air-side rotor 18 disposed within the housing 19. The flue gas-side rotor 15 is sleeved outside the flue gas passage 14, and the air-side rotor 18 is sleeved outside the air passage 17. A power-carrying wire 21 is provided inside the flue gas passage 14, and the power-carrying wire 21 is connected to a power source 20. The flue gas-side rotor 15 and the air-side rotor 18 are respectively connected to the thermally conductive bearing 16, and the thermally conductive bearing 16 is connected to the power source through a rotating shaft. The contact surface between the flue gas-side rotor 15 and the flue gas passage 14 is smooth, and the flue gas-side rotor 15 is fixed vertically by an extended annular support on the flue gas passage 14. Similarly, the contact surface between the air-side rotor 18 and the air passage 17 is smooth, and the air-side rotor 18 is fixed vertically by an extended annular support on the air passage 17.

[0041] The flue gas four-way valve 3 is connected to the flue gas inlet of the desulfurization tower 1, the first blower 2, and the condenser 4, and the flue gas passage 14, respectively; the flue gas three-way valve 6 is connected to the flue gas outlet of the condenser 4, the flue gas passage 14, and the atmospheric environment, respectively; as shown in Figure 4, the flue gas charging device 22 is located at the inlet of the flue gas passage 14; the inlet and outlet of the cooling circulation medium of the condenser 4 are connected to the cold storage device 9 through pipelines, respectively; the lower part of the condenser 4 is connected to the first closed water collection device 8 and the sewage pipe through the drain three-way valve 7, respectively; the outlet of the flue gas passage 14 is connected to the inlet of the gas-liquid separator 12, the liquid outlet of the gas-liquid separator 12 is connected to the second closed water collection device 10, and the gas outlet of the gas-liquid separator 12 is connected to the chimney 25; the inlet of the air passage 17 is connected to the second blower 5; the air three-way valve 23 is connected to the outlet of the air passage 17, the fresh air system 24, and the atmospheric environment, respectively.

[0042] In a preferred embodiment of the present invention, the cold storage device 9 includes an insulating shell, which is filled with an organic composite phase change material. The cooling medium circulation pipe is arranged in a circuitous manner within the organic composite phase change material, and the cooling medium circulation pipe is connected to the circulation medium inlet and outlet of the condensation device 4 respectively.

[0043] As shown in Figure 5, in a preferred embodiment of the present invention, the gas-liquid separation device 12 is Y-shaped, with the upper end of the straight pipe section serving as the inlet, the lower end of the straight pipe section connected to the liquid outlet, and the inclined pipe section connected to the gas outlet. A demister is installed inside the liquid outlet, and a vibrating wire grid 11 is installed inside the inclined pipe section. The demister is connected to positive electricity, and the vibrating wire grid 11 is grounded. Preferably, a one-way valve for flue gas backflow is provided at the upper part of the straight pipe section. Preferably, the demister is a baffle plate type, a ridge type, or a tubular type.

[0044] In a preferred embodiment of the present invention, the condensing device 4 is a tube bundle type, fin type or plate type, and the surface of the heat exchange component is provided with a hydrophobic layer.

[0045] In a preferred embodiment of the present invention, both the flue gas side rotor 15 and the air side rotor 18 are stainless steel hollow cylindrical structures with a plurality of radially arranged heat transfer plates inside; the outer shell 19 is sealed, the outer shell 19 on the side where the flue gas side rotor 15 is located is made of infrared transmitting material, and the outer shell 19 on the side where the air side rotor 18 is located is made of opaque material.

[0046] In a preferred embodiment of the present invention, the heat exchange components of the condensing device 4 are made of 1Cr18Ni9Ti, 2205 duplex stainless steel, or modified fluoroplastics. 2205 duplex stainless steel is further preferred, as its corrosion layer is less pronounced, with a corrosion thickness only half that of 1Cr18Ni9Ti. 2205 duplex stainless steel combines the high thermal conductivity and resistance to pitting, crevice corrosion, and chloride stress corrosion of ferritic stainless steel with the resistance to intergranular corrosion, good mechanical properties, and weldability of austenitic stainless steel. The chromium, molybdenum, and nitrogen content in 2205 duplex stainless steel gives it strong resistance to pitting and crevice corrosion in oxidizing and acidic solutions. Its thermal conductivity of 22 W / (m·K) is 63 times that of common polytetrafluoroethylene (PTFE) (0.35 W / (m·K)).

[0047] In a preferred embodiment of the present invention, the cooling circulation medium is an antifreeze medium.

[0048] The working method of the above-mentioned low-energy flue gas water-saving system includes:

[0049] As shown in Figures 6 and 7, in winter, flue gas from desulfurization tower 1 enters flue gas channel 14 through flue gas four-way valve 3 and flue gas charging device 22. The flue gas becomes charged at the flue gas charging device 22. Charged particles and droplets in the flue gas move towards the pipe wall under the Lorentz force of the magnetic field formed by the current-carrying conductor 21. The magnetic field exerts a Lorentz force on the charged particles and droplets moving in the direction of gravity towards the wall of flue gas channel 14. The formula for calculating the Lorentz force is:

[0050] F = BvQ

[0051] The direction of the Lorentz force is determined by the left-hand screw rule. The direction of the Lorentz force for charged particles and charged droplets in flue gas is shown in Figure 3.

[0052] Ambient air enters the air passage 17 through the second blower 5; the flue gas side rotor 15 and the air side rotor 18 rotate and exchange heat through the heat-conducting bearing 16. The flue gas in the flue gas passage 14 exchanges heat with the ambient temperature through radiation with the flue gas side rotor 15 and indirectly exchanges heat with the air in the air passage 17 before entering the gas-liquid separator 12; the droplets and liquid film are collected by the second sealed water collection device 10 through inertia and the interception of the demister; the demister is connected to positive electricity to repel the passage of charged droplets and particles, and the vibrating wire grid 11 is grounded and captured into the second sealed... Charged droplets in the water collection device 10 are prevented from being carried by the drag of flue gas; the separated condensate enters the second closed water collection device 10, and the flue gas enters the chimney 25; the air in the air passage 17 enters the fresh air system 24 through the air three-way valve 23; the first blower 2 sends the ambient air sprayed with rust remover into the condensation device 4, which removes dust and rust from the inside of the condensation device 4, and at the same time exchanges heat with the cooling circulating medium from the cold storage device 9. The cold storage device 9 stores cold, and the wastewater generated is discharged through the drain pipe, and the air is discharged into the atmosphere through the flue gas three-way valve 6;

[0053] As shown in Figure 8, in summer, the humid flue gas from desulfurization tower 1 enters the condensation device 4 and exchanges heat with the cooling circulating medium from the cold storage device 9. The resulting condensate enters the first closed water collection device 8 through the drain three-way valve 7. After heat exchange, the flue gas enters the flue gas passage 14 through the flue gas three-way valve 6 and the flue gas charging device 22. Ambient air enters the air passage 17 through the second blower 5. After heat exchange in the rotary heat exchanger 13, the air in the air passage 17 is discharged into the atmosphere through the air three-way valve 23. The flue gas in the flue gas passage 14 enters the gas-liquid separator 12. The separated condensate enters the second closed water collection device 10, and the flue gas enters the chimney 25. In summer, when the flue gas temperature at the gas outlet of the gas-liquid separator 12 is lower than the ambient air temperature, the air in the air passage 17 enters the fresh air system 24 through the air three-way valve 23. At this time, the rotary heat exchanger 13 acts as a plume removal device to heat the flue gas and reduce plume formation.

[0054] The following specific calculation example will be used to verify the effectiveness of the present invention:

[0055] Calculations were performed to verify that the moisture recovery from flue gas is closely related to the flue gas temperature. Taking Inner Mongolia as an example, the average daytime high temperature in summer is 23℃, and the average nighttime temperature is 10℃, with an average temperature range of 20.1℃ to 25.3℃ (Figure 9). Experiments showed that the flue gas temperature decreased by 13.6℃, ​​11.3℃, 10.2℃, 8.5℃, and 6.1℃ at cooling water temperatures of 20℃, 25℃, 30℃, 35℃, and 40℃, respectively. Within this range, the flue gas temperature change was basically linear, and the actual temperature decrease was slower than the linear increase due to the increased heat transfer resistance caused by the thickening of the liquid film. Based on linear prediction, the flue gas temperature decreased to 21℃ at a cooling medium temperature of 0℃, and the outlet flue gas temperature was 29℃. Further cooling with a rotary air-cooling device is still valuable in summer. The decrease in flue gas temperature determines the amount of water recovered. Flue gas velocities of 3–11 m / s will generate 10%–30% droplet carry-over. Theoretically, if the flue gas does not carry droplets, the condensation water recovery amount can be calculated using saturated vapor pressure.

[0056] Ps=10^(7.07406-(1657.46 / (T+227.02)))

[0057] Where Ps is the saturation pressure at flue gas temperature T.

[0058] The theoretical water recovery rate is calculated by determining the moisture content and water vapor mass fraction at the inlet and outlet using saturation pressure.

[0059] In the experiment, the water recovery rates of the condensation device at flue gas temperature differences of 20℃, 25℃, 30℃, 35℃ and 40℃ were 52.41%, 44.76%, 39.61%, 31.05% and 24.63%, respectively. The phase change temperature of the composite phase change cold storage material ranged from -10℃ to 20℃. Taking Inner Mongolia as an example, the average winter temperature in northern China is -6℃ to 5℃. For the phase change cold storage material, paraffin wax can be selected because it is inexpensive and has good chemical stability, or the binary organic phase change cold storage material TD-LA, which has better thermal conductivity and higher energy storage density but is relatively more expensive, can be selected. The phase change temperature is 4.3℃, the latent heat of phase change is 247J / g, and the thermal conductivity is 0.274W / (m·K). Experiments were conducted on heat exchangers made of fluoroplastic and 2205 duplex stainless steel, both being tube bundle heat exchangers, to investigate their thermal conductivity. Under the conditions of a constant flue gas velocity of 6 m / s and a cooling water temperature of 30℃, the heat transfer coefficient of fluoroplastic was 184 W / (m²). 2 The heat transfer coefficient of the 2205 duplex stainless steel heat exchanger is 391 W / (m³). 2 ·K), and for fluoroplastic heat exchangers, further increasing the flue gas velocity to 15 m / s results in a heat transfer coefficient of 190 W / (m). 2 The heat transfer coefficient of the 2205 duplex stainless steel heat exchanger increases to 0.581 W / (m³) when the flue gas velocity is 15 m / s. 2The heat exchange efficiency increased significantly (K).

[0060] The latent heat accounts for a large proportion of flue gas condensation. Taking a flue gas velocity of 6 m / s and a cooling water temperature of 25℃ as an example, the latent heat is 20.49 kJ and the sensible heat is 3.65 kJ. The experiment used a Consay ICA-10 chiller with a cooling capacity of 29.5 kW. The minimum cooling water temperature set was only 20℃ at a flue gas velocity of 3 m / s. The experimentally used 3 kW fan, adjustable via baffles, could achieve flue gas velocities of 3–15 m / s. This demonstrates that using a blower for winter storage air cooling significantly improves water conservation while saving energy. Linear prediction from the experiment indicates that when the cooling medium temperature is 0℃, the flue gas outlet temperature will be 29℃, higher than the average summer temperature of Inner Mongolia (20.1–25.3℃). Further cooling through heat conduction and radiation can be achieved using a rotating air-cooling device. At a flue gas temperature of 29℃, the water recovery rate can reach 68.6%. In Inner Mongolia, extreme summer temperatures range from 35°C to 45°C. At these temperatures, a rotary air-cooling device cools the air through heat exchange and supplies it to the fresh air system. Simultaneously, it heats the moist flue gas to prevent the emission of white plumes. The rotary air-cooling device achieves a small volume with a high heat transfer surface through rotation. Rotation facilitates indirect heat exchange between the air and flue gas through contact heat conduction, and also generates radiation with the environment. The radiation energy is related to the fourth power of temperature. Rotation allows for sufficient radiative heat exchange with the cold environment, especially the 2.5K low-temperature environment of space. The air-side rotor shell is made of opaque material to prevent heat exchange between the air supplied to the fresh air system and the environment after heat exchange.

[0061] The gas-liquid separator utilizes the high static pressure within the water collection device, where the flue gas has no velocity, and the condensate is collected by the water collection device due to inertia. The total pressure equals the static pressure plus the dynamic pressure; when the static pressure is high, the dynamic pressure is zero.

[0062]

[0063] The above description is only a part of the embodiments of the present invention. Although some terms are used in the present invention, the possibility of using other terms is not excluded. The use of these terms is merely for the convenience of describing and explaining the essence of the present invention, and interpreting them as any kind of additional limitation would contradict the spirit of the present invention. The above description is only to further illustrate the content of the present invention through embodiments to facilitate easier understanding, but it does not mean that the embodiments of the present invention are limited to this. Any technical extension or re-creation based on the present invention is protected by the present invention.

Claims

1. A low-energy flue gas water-saving system, characterized in that, The system includes a first blower (2), a flue gas four-way valve (3), a condenser (4), a second blower (5), a flue gas three-way valve (6), a sewage three-way valve (7), a first closed water collection device (8), a cold storage device (9), a second closed water collection device (10), a gas-liquid separator (12), a rotary heat exchanger (13), a flue gas charging device (22), and an air three-way valve (23); the rotary heat exchanger (13) includes a housing (19) and a flue gas passage (1) provided inside the housing (19). 4) Flue gas side rotor (15), thermally conductive bearing (16), air passage (17), and air side rotor (18); the flue gas side rotor (15) is sleeved outside the flue gas passage (14), and the air side rotor (18) is sleeved outside the air passage (17); a power-conducting wire (21) is provided inside the flue gas passage (14), and the power-conducting wire (21) is connected to a power source (20); the flue gas side rotor (15) and the air side rotor (18) are respectively connected to the thermally conductive bearing (16), and the thermally conductive bearing (16) is connected through a rotating shaft. Power source; flue gas four-way valve (3) is connected to the flue gas inlet and flue gas passage (14) of desulfurization tower (1), first blower (2), and condenser (4) respectively; flue gas three-way valve (6) is connected to the flue gas outlet of condenser (4), flue gas passage (14) and atmospheric environment respectively; flue gas charging device (22) is located at the inlet of flue gas passage (14); the inlet and outlet of cooling circulation medium of condenser (4) are connected to cold storage device (9) through pipelines respectively; the lower part of condenser (4) is connected to the drain tee Valve (7) is connected to the first closed water collection device (8) and the sewage pipe respectively; the outlet of flue gas passage (14) is connected to the inlet of gas-liquid separator (12), the liquid outlet of gas-liquid separator (12) is connected to the second closed water collection device (10), and the gas outlet of gas-liquid separator (12) is connected to the chimney (25); the inlet of air passage (17) is connected to the second blower (5); and the three-way air valve (23) is connected to the outlet of air passage (17), the fresh air system (24), and the atmospheric environment respectively.

2. The low-energy flue gas water-saving system according to claim 1, characterized in that, The cold storage device (9) includes an insulating shell, which is filled with an organic composite phase change material. A cooling medium circulation pipe is arranged in a circuitous manner inside the organic composite phase change material. The cooling medium circulation pipe is connected to the circulation medium inlet and outlet of the condensation device (4).

3. The low-energy flue gas water-saving system according to claim 1, characterized in that, The gas-liquid separation device (12) is Y-shaped. The upper end of the straight pipe section is the inlet, the lower end of the straight pipe section is connected to the liquid outlet, and the inclined pipe section is connected to the gas outlet. A demisting device is installed in the liquid outlet, and a vibrating wire grid (11) is installed in the inclined pipe section. The demisting device is connected to positive power, and the vibrating wire grid (11) is grounded.

4. The low-energy flue gas water-saving system according to claim 3, characterized in that, The upper part of the straight pipe section is equipped with a one-way valve for flue gas backflow.

5. The low-energy flue gas water-saving system according to claim 3, characterized in that, The defogging device can be a baffle plate type, a ridge type, or a tubular type.

6. The low-energy flue gas water-saving system according to claim 1, characterized in that, The condenser (4) is a tube bundle type, fin type or plate type, and the surface of the heat exchange component is provided with a hydrophobic layer.

7. The low-energy flue gas water-saving system according to claim 1, characterized in that, Both the flue gas side rotor (15) and the air side rotor (18) are stainless steel hollow cylindrical structures with several heat transfer plates arranged radially inside; the outer shell (19) is sealed, the outer shell (19) on the side where the flue gas side rotor (15) is located is made of infrared transmitting material, and the outer shell (19) on the side where the air side rotor (18) is located is made of opaque material.

8. The low-energy flue gas water-saving system according to claim 1, characterized in that, The heat exchange components of the condensing device (4) are made of 1Cr18Ni9Ti, 2205 duplex stainless steel or modified fluoroplastic.

9. The operating method of the low-energy flue gas water-saving system according to any one of claims 1 to 8, characterized in that, include: In winter, flue gas from the desulfurization tower (1) enters the flue gas passage (14) through the flue gas four-way valve (3) and the flue gas charging device (22). The flue gas is charged at the flue gas charging device (22). Charged particles and charged droplets in the flue gas move toward the pipe wall under the Lorentz force of the magnetic field formed by the current-carrying wire (21). Ambient air enters the air passage (17) through the second blower (5). The flue gas side rotor (15) and the air side rotor (18) rotate and exchange heat through the heat-conducting bearing (16). The flue gas in the flue gas passage (14) exchanges heat with the ambient temperature through radiation with the flue gas side rotor (15) and indirectly exchanges heat with the air in the air passage (17) before entering the gas-liquid separation device (12). The separated condensate enters the second closed water collection device (10), and the flue gas enters the chimney (25). The air in the air passage (17) enters the fresh air system (24) through the air three-way valve (23). The first blower (2) sends the ambient air sprayed with rust remover into the condensation device (4) to remove dust and rust inside the condensation device (4). The gas exchange heat with the cooling circulating medium from the cold storage device (9), the cold storage device (9) stores cold, the wastewater generated is discharged through the drain pipe, and the air is discharged into the atmosphere through the flue gas three-way valve (6); in summer, the humid flue gas from the desulfurization tower (1) enters the condensing device (4), exchanges heat with the cooling circulating medium from the cold storage device (9), and the condensate generated enters the first closed water collection device (8) through the drain three-way valve (7); the flue gas after heat exchange enters the flue gas passage (14) through the flue gas three-way valve (6) and the flue gas charging device (22), the ambient air enters the air passage (17) through the second blower (5), after heat exchange in the rotary heat exchange device (13), the air in the air passage (17) is discharged into the atmosphere through the air three-way valve (23), the flue gas in the flue gas passage (14) enters the gas-liquid separation device (12), the separated condensate enters the second closed water collection device (10), and the flue gas enters the chimney (25).

10. The working method of the low-energy flue gas water-saving system according to claim 9, characterized in that, In summer, when the flue gas temperature at the gas outlet of the gas-liquid separator (12) is lower than the ambient air temperature, the air in the air passage (17) enters the fresh air system (24) through the air three-way valve (23).

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