A Highly Efficient and Energy-Saving Wet Treatment Method for Moist Flue Gas

Abstract

This invention discloses a highly efficient and energy-saving wet treatment method for humid flue gas, comprising the following steps: humid flue gas is sequentially passed through a first-stage wet scrubbing unit for coarse dust removal via collision, then enters a second-stage wet fine treatment unit for deep purification and demisting, before being discharged; wherein, deep purification includes countercurrent contact between the flue gas and washing liquid, followed by multi-stage gas-liquid separation; washing wastewater generated from the first and second-stage units is collected in a solid-liquid separation device for sedimentation separation, and the separated supernatant is introduced into a circulating water storage unit; water in the circulating water storage unit is reused in the first-stage wet scrubbing unit; a portion of the liquid collected at the bottom of the second-stage wet fine treatment unit is returned to the top of the unit for recycling, and a portion is discharged as wastewater into the solid-liquid separation device; water is replenished to the circulating water storage unit and / or the return system of the second-stage unit; sludge generated at the bottom of the solid-liquid separation device is dewatered to form dried sludge cakes for external use.

Description

Technical Field

[0001] This invention relates to the field of industrial flue gas purification technology, and in particular to a highly efficient and energy-saving wet treatment method for humid flue gas. Background Technology

[0002] In industrial production processes such as steel, chemicals, and building materials, large quantities of high-temperature, moisture-containing flue gas are generated. This type of flue gas typically carries significant amounts of pollutants such as dust and acid mist; direct emission of such gas would pose serious threats to the atmospheric environment and human health. With increasingly stringent environmental standards, particularly the ultra-low emission standard requiring particulate matter concentrations in flue gas to be ≤10 mg / m³, the efficient purification and treatment of moisture-containing flue gas presents even greater challenges.

[0003] Baghouse dust collectors offer high efficiency for dry flue gas. However, when applied to humid flue gas, the moisture in the gas easily condenses with dust particles on the filter bag surface, causing "bag clogging." This not only leads to a sharp increase in system operating resistance and energy consumption but also significantly shortens the filter bag's lifespan, increasing maintenance costs and downtime frequency. More importantly, "bag clogging" significantly reduces dust collection efficiency, making it difficult to consistently meet ultra-low emission requirements.

[0004] Wet electrostatic precipitators (ESPs) use a high-voltage electric field to charge droplets and particulate matter, which are then captured, theoretically offering good removal efficiency for fine particles. However, they have significant drawbacks: First, maintaining a continuous water film on the electrodes to prevent scale buildup requires a large amount of process water, resulting in severe water waste. Second, the operation of the high-voltage electric field itself is extremely energy-intensive. Furthermore, in high-temperature and high-humidity flue gas environments, electrodes and insulating components are prone to corrosion or condensation and short circuits, leading to poor system reliability and stability, and high maintenance costs.

[0005] Traditional wet scrubbing technologies, employing wet processes such as spray towers, can effectively reduce flue gas temperature and remove some pollutants. However, they often suffer from low system integration and rudimentary water recycling designs. Common problems include low water resource utilization, easy scaling and clogging of the circulating water system, and incomplete sludge treatment (usually simple discharge or landfill), leading to secondary pollution risks. Furthermore, single scrubbing methods have limited efficiency in capturing submicron particles, making it difficult to independently ensure stable ultra-low emissions.

[0006] In summary, existing technologies for treating wet flue gas have significant drawbacks, such as high energy consumption, susceptibility to failure, high water consumption, high operating costs, unstable emissions, and the risk of secondary pollution. These technologies make it difficult to achieve an ideal balance between long-term stable operation, energy conservation and consumption reduction, and the realization of ultra-low emissions. Summary of the Invention

[0007] In order to overcome the above-mentioned shortcomings of the prior art, the purpose of this invention is to provide a highly efficient and energy-saving wet treatment method for humid flue gas, so as to solve the problems mentioned in the background art.

[0008] The technical solution adopted by this invention to solve its technical problem is: a highly efficient and energy-saving wet treatment method for humid flue gas, comprising the following steps:

[0009] Flue gas purification: The humid flue gas is sequentially passed through the first-stage wet dust removal unit for coarse dust removal by collision, and then enters the second-stage wet fine treatment unit for deep purification and demisting, and is then discharged from the chimney by an induced draft fan; wherein, the deep purification includes making the flue gas come into countercurrent contact with the washing liquid and undergoing multi-stage gas-liquid separation.

[0010] Water circulation and treatment: The washing wastewater generated by the first and second stage units is collected in a solid-liquid separation device for sedimentation and separation. The supernatant separated is introduced into a circulating water storage unit. The water in the circulating water storage unit is reused in the first stage wet dust removal unit. At the same time, part of the liquid collected at the bottom of the second stage wet fine treatment unit is returned to the top of the unit for recycling, and part of it is discharged into the solid-liquid separation device as sludge. Fresh water is added to the circulating water storage unit and / or the return system of the second stage unit. The sludge generated at the bottom of the solid-liquid separation device is dewatered to form dried sludge cakes, which are then transported off-site for utilization.

[0011] As a further improvement of the present invention: the flue gas purification step includes:

[0012] The humid flue gas is sequentially passed through a venturi dust collector for coarse dust removal, then enters a fine dust removal tower for deep purification, and finally discharged from the chimney by an induced draft fan. The deep purification process in the fine dust removal tower includes: the flue gas flowing from bottom to top within the tower, sequentially undergoing countercurrent contact washing with a washing liquid sprayed from top to bottom, and then sequentially passing through at least one demister for gas-liquid separation to remove fine particles and droplets from the flue gas.

[0013] As a further improvement of the present invention: the sedimentation separation process in the water circulation and treatment steps includes:

[0014] Wastewater and dust from the Venturi scrubber are discharged into a sedimentation tank for solid-liquid separation. The supernatant separated from the sedimentation tank overflows into a circulating water tank for storage. The water in the circulating water tank is supplied to the Venturi scrubber for recycling through a first water pump.

[0015] As a further improvement of the present invention: the solid-liquid separation process in the water circulation and treatment step includes:

[0016] The liquid formed at the bottom of the dust removal tower during the spraying and demisting process is collected and transported back to the spray layer of the dust removal tower for recycling through a second water pump installed inside the tower, forming an internal circulation within the tower; at the same time, a portion of the wastewater in the internal circulation system is discharged into the sedimentation tank in a fixed proportion.

[0017] Fresh production water is added to the circulating water tank and / or the internal circulation system of the dust removal tower to maintain the system water balance;

[0018] The concentrated sludge deposited at the bottom of the sedimentation tank is transported to a filter press for dewatering, forming sludge cakes which are then transported off-site for resource utilization.

[0019] As a further improvement of the present invention: the at least one stage of the dust removal tower includes a tube bundle demister, a plate demister and a wire mesh demister arranged sequentially along the flue gas flow direction. The flue gas passes through the centrifugal separation of the tube bundle demister, the deflection and impact separation of the plate demister and the interception separation of the wire mesh demister in sequence, so as to achieve efficient demisting and dehydration in stages.

[0020] As a further improvement of the present invention: the dust removal tower is provided with multiple spray layers, and the flue gas passes through the washing liquid curtain formed by each spray layer from bottom to top. The spacing between the spray layers is 1.5-2.5 meters, and the operating pressure of the spray liquid is 0.2-0.6 MPa.

[0021] As a further improvement of the present invention: the flue gas velocity at the throat of the Venturi dust collector is controlled within the range of 50-90m / s during operation, so that the flue gas and the washing liquid will generate violent inertial collisions to capture large dust particles.

[0022] As a further improvement of the present invention, it also includes an intelligent control step: by monitoring operating parameters through sensors set at key nodes of the system, the central controller dynamically adjusts relevant execution components according to the operating parameters to optimize system energy consumption and operational stability.

[0023] As a further improvement of the present invention, the intelligent control steps specifically include on-demand spray optimization control: real-time monitoring of the dust concentration of the humid flue gas before entering the Venturi dust collector or after being discharged from the fine dust removal tower; and dynamically adjusting the operating frequency of the second water pump supplying the spray layer of the fine dust removal tower, or adjusting the opening of the regulating valve on the spray pipeline, based on the real-time changes in the dust concentration.

[0024] As a further improvement of the present invention, the water circulation and treatment steps further include: fresh production water replenished to the system is supplied to the internal circulation system of the dust removal tower to maintain its water quality and quantity balance.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] This invention employs a venturi tube for high-speed inertial impaction coarse dust removal, combined with a deep purification process involving spray washing and multi-stage mechanical demisting within a fine treatment tower. Through progressive enhancement and synergy, it improves the collection efficiency of fine particulate matter and droplets, ensuring that flue gas emissions consistently meet the ultra-low emission standard of particulate matter concentration ≤10mg / m³. By reusing wastewater according to its quality, it maximizes the recycling of water resources, achieving a water saving rate of over 80%. Simultaneously, the dewatered and dried sludge is reused as raw material in the production process, eliminating secondary pollution from solid waste. Through an intelligent control system, the spray volume and chemical dosage are dynamically optimized based on flue gas load and water quality parameters, effectively reducing system power and material consumption while ensuring treatment effectiveness, and improving operational stability and automation level. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the method flow structure of the present invention;

[0028] Figure 2 This is a schematic diagram of the system structure of the present invention;

[0029] Attached reference numerals: 1. Moist flue gas; 2. Venturi scrubber; 3. Settling chamber; 4. Connecting pipe; 5. Fine dust collector; 6. Flue gas outlet pipe; 7. Exhaust fan; 8. Chimney; 9. Scrubber exhaust pump; 10. Sedimentation tank exhaust pump; 11. Sedimentation tank; 12. Circulation tank; 13. Clear water tank; 14. Process water pump; 15. Venturi circulation pump; 16. Production water; 17. Plate and frame filter press; 501. Wire mesh demister; 502. Plate demister; 503. Tube bundle demister; 504. Spray layer; 505. Packing layer; 506. Spray circulation pump; 507. Valve. Detailed Implementation

[0030] In order to clearly and completely understand the technical solution, the present invention will be further described in conjunction with the embodiments and accompanying drawings. Obviously, the described embodiments are only some 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.

[0031] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0032] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0033] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0034] Embodiments of the present invention provide a highly efficient and energy-saving wet treatment method for humid flue gas, comprising the following steps:

[0035] Flue gas purification: The humid flue gas is sequentially passed through the first-stage wet dust removal unit for coarse dust removal by collision, and then enters the second-stage wet fine treatment unit for deep purification and demisting, and is then discharged from the chimney by an induced draft fan; wherein, the deep purification includes making the flue gas come into countercurrent contact with the washing liquid and undergoing multi-stage gas-liquid separation.

[0036] Water circulation and treatment: The washing wastewater generated by the first and second stage units is collected in a solid-liquid separation device for sedimentation and separation. The supernatant separated is introduced into a circulating water storage unit. The water in the circulating water storage unit is reused in the first stage wet dust removal unit. At the same time, part of the liquid collected at the bottom of the second stage wet fine treatment unit is returned to the top of the unit for recycling, and part of it is discharged into the solid-liquid separation device as sludge. Fresh water is added to the circulating water storage unit and / or the return system of the second stage unit. The sludge generated at the bottom of the solid-liquid separation device is dewatered to form dried sludge cakes, which are then transported off-site for utilization.

[0037] A two-stage wet treatment process, combining coarse dust removal via collision and deep purification / demisting, along with countercurrent contact and multi-stage gas-liquid separation, enhances the overall removal efficiency of particulate matter and droplets. The first stage utilizes high-speed collision to initially remove large particles, reducing the load on the second stage. The second stage, through the synergistic effect of countercurrent washing and multi-stage separation, effectively captures submicron particles and reduces flue gas humidity, ensuring the outlet flue gas consistently meets the ultra-low emission standard of ≤10mg / m³ particulate matter concentration, while effectively avoiding common problems of traditional technologies such as bag clogging or corrosion. The fine treatment unit internally achieves partial self-circulation of the spray liquid, while externally, wastewater is purified through sedimentation and reused in the coarse dust removal unit. Combined with proportional wastewater discharge and targeted water replenishment, this significantly reduces fresh water consumption and improves the system's water-saving rate. Simultaneously, the settled sludge, after dewatering, forms dried sludge cakes that can be transported off-site as raw materials, achieving resource-based disposal of solid waste with virtually no secondary wastewater discharge.

[0038] In one embodiment of the present invention, the flue gas purification step includes:

[0039] The humid flue gas is sequentially passed through a venturi dust collector for coarse dust removal, then enters a fine dust removal tower for deep purification, and finally discharged from the chimney by an induced draft fan. The deep purification process in the fine dust removal tower includes: the flue gas flowing from bottom to top within the tower, sequentially undergoing countercurrent contact washing with a washing liquid sprayed from top to bottom, and then sequentially passing through at least one demister for gas-liquid separation to remove fine particles and droplets from the flue gas.

[0040] Venturi scrubbers utilize high-speed inertial collisions to efficiently remove large dust particles from humid flue gas and perform initial cooling and humidification, creating favorable conditions for subsequent deep purification. The fine dust removal tower employs a counter-current contact method between bottom-up flue gas and top-down spray liquid, greatly increasing the gas-liquid contact area and time, and improving the mass transfer and capture efficiency of fine particulate matter and gaseous pollutants. Following this is at least one demister specifically designed to remove fine droplets and slurry entrained in the flue gas. This multi-stage separation ensures the cleanliness and dryness of the flue gas outlet.

[0041] In one embodiment of the present invention, the sedimentation separation process of the water circulation and treatment steps includes:

[0042] Wastewater and dust from the Venturi scrubber are discharged into a sedimentation tank for solid-liquid separation. The supernatant separated from the sedimentation tank overflows into a circulating water tank for storage. The water in the circulating water tank is supplied to the Venturi scrubber for recycling through a first water pump.

[0043] By channeling the wastewater generated by the Venturi scrubber into a sedimentation tank for solid-liquid separation, and then using the supernatant to supply a circulating water tank, a directional local water circulation loop is formed. This allows the large amount of washing water required by the Venturi scrubber to be recycled to the maximum extent within its own process unit. The sedimentation tank effectively removes most of the suspended solids from the wastewater through gravity settling, preventing nozzle clogging, pipe wear, or reduced dust removal efficiency that could occur if untreated turbid water is directly reused. The supernatant, after sedimentation and purification, is stored in the circulating water tank, which plays a role in stabilizing water quality and buffering water volume, smoothing out water quality fluctuations, and providing a continuous water supply to the Venturi scrubber via the first water pump, thereby ensuring the continuity and stability of the coarse dust removal process.

[0044] In one embodiment of the present invention, the solid-liquid separation process of the water circulation and treatment step includes:

[0045] The liquid formed at the bottom of the dust removal tower during the spraying and demisting process is collected and transported back to the spray layer of the dust removal tower for recycling through a second water pump installed inside the tower, forming an internal circulation within the tower; at the same time, a portion of the wastewater in the internal circulation system is discharged into the sedimentation tank in a fixed proportion.

[0046] Fresh production water is added to the circulating water tank and / or the internal circulation system of the dust removal tower to maintain the system water balance;

[0047] The concentrated sludge deposited at the bottom of the sedimentation tank is transported to a filter press for dewatering, forming sludge cakes which are then transported off-site for resource utilization.

[0048] By installing a second water pump inside the dust removal tower, the liquid at the bottom of the tower is directly returned to the spray layer, forming a small circulation within the tower. This improves water resource utilization efficiency and reduces energy consumption from external water transportation. Combined with a fixed-ratio blowdown system, it continuously removes dissolved solids, fine suspended matter, and some pollutants concentrated by evaporation and reaction within the tower. This effectively prevents scaling, corrosion, or spray blockage caused by excessive accumulation of these substances in the circulating liquid, thus ensuring the long-term stable operation of the core purification components of the dust removal tower.

[0049] By replenishing fresh production water to the circulating water tank and / or the internal circulation system of the tower, the replenishment water is mainly used to compensate for the water loss caused by system evaporation, sewage discharge and sludge carry-away. The flexibility of the replenishment path allows for optimization and adjustment based on actual water quality monitoring.

[0050] The concentrated sludge at the bottom of the sedimentation tank is transported to a filter press for dewatering, transforming the solid pollutants, such as dust, captured in the flue gas from a liquid sludge-water state into a solid sludge cake with low water content, thus achieving a change in the form of pollutants and a significant reduction in volume. The sludge cake is then transported off-site for resource utilization, being converted into reusable raw materials, thus cutting off the secondary pollution pathway caused by its use as waste in landfills or improper disposal.

[0051] In one embodiment of the present invention, the at least one stage demister of the dust removal tower includes a tube bundle demister, a plate demister and a wire mesh demister arranged sequentially along the flue gas flow direction. The flue gas passes through the centrifugal separation of the tube bundle demister, the deflection and impact separation of the plate demister and the interception separation of the wire mesh demister in sequence, so as to achieve efficient demisting and dehydration in stages.

[0052] The tube bundle demister, as the first stage, utilizes the centrifugal force generated by high-speed rotation to efficiently separate larger droplets and slurry agglomerates carried in the flue gas, completing coarse demisting and reducing the load on subsequent stages. Subsequently, the flue gas enters the plate demister, where multiple deflections and impacts within its tortuous channels effectively capture droplets of similar particle size. Finally, the wire mesh demister, as the final fine filter, uses the interception and inertial collision of its fine fibers to capture micron and submicron-sized droplets that are difficult to remove in the first two stages, achieving full coverage of droplets across the entire particle size spectrum. This ensures that the flue gas reaches extremely low moisture content and droplet entrainment before emission.

[0053] In one embodiment of the present invention, the dust removal tower is provided with multiple spray layers, and the flue gas passes through the washing liquid curtain formed by each spray layer from bottom to top. The spacing between the spray layers is 1.5-2.5 meters, and the operating pressure of the spray liquid is 0.2-0.6 MPa.

[0054] By setting up multiple spray layers and allowing the flue gas to pass through them sequentially from bottom to top, a multi-stage washing reaction zone is constructed. This significantly extends the total contact time and contact area between the gas and liquid phases, giving fine particulate matter and some gaseous pollutants in the flue gas more opportunities to be captured by droplets through mechanisms such as collision, interception, and dissolution, thereby improving the overall purification efficiency.

[0055] In one embodiment of the present invention, the flue gas velocity at the throat of the venturi dust collector is controlled within the range of 50-90 m / s during operation, so that the flue gas and the washing liquid will generate violent inertial collisions to capture large dust particles.

[0056] In one embodiment of the present invention, an intelligent control step is also included: monitoring operating parameters by sensors installed at key nodes of the system, and dynamically adjusting relevant execution components by the central controller according to the operating parameters to optimize system energy consumption and operational stability.

[0057] By installing sensors at key nodes, such as flue gas flow meters, online dust concentration monitors, circulating water conductivity / pH sensors, and level gauges, the system can acquire core parameters reflecting its operating status in real time. Based on this real-time data, the central controller dynamically adjusts relevant actuators through preset control logic, such as PID algorithms, fuzzy control, or more advanced model predictive control. This allows the system to automatically adapt to fluctuations in operating conditions such as flue gas load and water composition, stabilizing key process parameters within their optimal range. This ensures long-term stable achievement of purification standards, overcoming the shortcomings of traditional manual operation or simple on / off control, which is often slow and inefficient.

[0058] In one embodiment of the present invention, the intelligent control step specifically includes on-demand spray optimization control: real-time monitoring of the dust concentration of the humid flue gas before entering the Venturi dust collector or after being discharged from the fine dust removal tower; dynamically adjusting the operating frequency of the second water pump supplying the spray layer of the fine dust removal tower, or adjusting the opening of the regulating valve on the spray pipeline, according to the real-time change of the dust concentration.

[0059] By monitoring dust concentration at key nodes in real time, the system can identify changes in operating conditions. When the concentration increases, it automatically intensifies the spraying to ensure that pollutants are fully captured; when the concentration decreases, it automatically weakens the spraying to avoid energy waste caused by overtreatment.

[0060] In one embodiment of the present invention, the water circulation and treatment step further includes: fresh production water replenished to the system is supplied to the internal circulation system of the dust removal tower to maintain its water quality and quantity balance.

[0061] The implementation process of this invention includes:

[0062] Moist flue gas passes through a flue gas collection duct and enters a venturi dust collector for preliminary treatment, initially removing large dust particles. Inertial dust removal is achieved through high-speed airflow and droplet collision. The pre-treated flue gas then passes through a connecting duct between the venturi dust collector and the fine dust collector, and enters the fine dust collector for further treatment. The fine dust collector integrates a spray layer (3 layers, spaced 2m apart), a tube bundle demister, a plate demister, and a wire mesh demister, removing fine particles and droplets step by step. The treated flue gas is discharged from the top of the fine dust collector, and then, driven by an induced draft fan, is discharged into the chimney through the flue gas dust removal duct, meeting emission standards for external discharge.

[0063] After the moist flue gas undergoes preliminary treatment in the venturi tube, a portion of the sludge enters the settling chamber and is then discharged into the sedimentation tank along the sewage pipe.

[0064] The flue gas enters the chimney of the fine dust collector and flows from bottom to top, passing through the spray layer, tube bundle demister, plate demister, and wire mesh demister in sequence. After being washed by production water, the flue gas is purified and discharged from the top of the fine dust collector.

[0065] A spray layer is a commonly used waste gas treatment device. It uses sprayed liquid (such as water or solution) to contact pollutants in the waste gas, thereby achieving dissolution, adsorption or reaction, and thus purifying the waste gas. This fine dust collector is equipped with 3 spray layers, with each layer spaced about 2 meters apart. Each spray layer is equipped with a spray layer circulating water pump to pump back the bottom flushing water for reuse in the spray layer.

[0066] The working principle of a tube bundle demister is to separate mist droplets and dust particles from flue gas through a high-speed rotating airflow. When flue gas passes through the tube bundle demister, the airflow becomes a rotating airflow as it passes through the gaps between the plate blades. Under the action of inertia, the droplets adhere to the outer wall, agglomerate into larger particles, and collect in the overflow groove, flowing down the outer wall to achieve the purpose of demisting.

[0067] The working principle of a plate demister is mainly based on the principle of water film separation to achieve gas-water separation. When flue gas carrying droplets enters the tortuous channel, the droplets are separated, and the particles settle down during the impact process, thereby achieving the purpose of demisting. This plate demister is installed horizontally. It utilizes the inertia of mist particles in the moving airflow. By suddenly changing the direction of the mist-laden airflow, the mist particles deviate from the airflow under the action of inertia, impact the folded plates, and are separated (removed).

[0068] The working principle of a wire mesh demister is mainly based on the inertial impact and interception of droplets. When gas containing droplets passes through the wire mesh, the droplets are deflected towards the wire mesh due to the inertial force of the gas flow. After hitting the wire mesh, the droplets fall into the collection tank due to gravity, thus achieving the separation of droplets and gas.

[0069] The bottom of the fine dust collector is equipped with a housing. The sludge and wastewater generated during the washing of moist flue gas are discharged through the bottom of the fine dust collector and then pumped by an external pump from the scrubbing tower to a sedimentation tank. The sedimentation tank receives the sludge-water mixture from the venturi dust collector and separates the sludge and clean water through gravity settling. The overflow clean water from the sedimentation tank is reused in the venturi dust collector.

[0070] A spray water recycling system is set up, including a sedimentation tank, a circulation tank, and a clear water tank. Water from the Venturi dust collector and the fine dust collector is discharged to the sedimentation tank through pipelines and an external drainage pump. An overflow hole is set at the top of the sedimentation tank, and the water after sedimentation overflows into the circulation tank. Then, it is pumped back to the Venturi dust collector for recycling by a Venturi circulation pump. The sludge treated in the sedimentation tank is pumped to a plate and frame filter press for further treatment by an external drainage pump. After that, it is transported by truck to the raw material and sintering processes for recycling.

[0071] The water used for spraying in the fine dust collector is production water. A clear water tank is set up, and the production water is stored in the clear water tank. It is then pumped to the top of the fine dust collector by a process water pump and used for spraying the wire mesh demister, plate demister, and tube bundle demister.

[0072] Venturi throat flow velocity: 60-80m / s; spray layer water pressure: 0.3-0.5MPa; circulating water pH value: 6-8.

[0073] In summary, after reading this invention document, those skilled in the art can make various other corresponding modifications to the technical solutions and concepts based on this invention without creative mental effort, and all of these modifications fall within the scope of protection of this invention.

Claims

1. A highly efficient and energy saving wet process for treating moist flue gas, characterized in that, The method comprises the following steps: Flue gas purification: the wet flue gas is sequentially subjected to collision rough dust removal in a first-stage wet dust removal unit, and then subjected to deep purification and mist removal in a second-stage wet fine treatment unit, and finally discharged from a chimney through an induced draft fan; wherein the deep purification comprises countercurrent contact of the flue gas with scrubbing liquid and multi-stage gas-liquid separation; Water circulation and treatment: the scrubbing wastewater generated by the first-stage and second-stage units is collected to a solid-liquid separation device for sedimentation separation, the separated supernatant is introduced into a circulating water storage unit, the water in the circulating water storage unit is reused in the first-stage wet dust removal unit, the liquid part collected at the bottom of the second-stage wet fine treatment unit is refluxed to the top of the unit for recycling, and part of the liquid part is discharged as blowdown liquid into the solid-liquid separation device, fresh water is supplemented to the circulating water storage unit and / or the reflux system of the second-stage unit, and the sludge generated at the bottom of the solid-liquid separation device is dewatered to form dried sludge cake and is transported out for utilization.

2. A highly efficient and energy saving wet flue gas treatment process according to claim 1, characterized in that, The flue gas purification step comprises: The wet flue gas sequentially flows through a venturi dust collector for rough dust removal, and then enters a fine dust removal tower for deep purification, and finally is discharged from a chimney through an induced draft fan; wherein the deep purification of the fine dust removal tower comprises: the flue gas flows from bottom to top in the tower, sequentially countercurrently contacts and is washed by the scrubbing liquid sprayed from top to bottom, and then sequentially passes through at least one mist eliminator for gas-liquid separation to remove fine particles and mist droplets in the flue gas.

3. A highly efficient and energy saving wet flue gas treatment process according to claim 1, characterized in that, The sedimentation separation process of the water circulation and treatment step comprises: The wastewater from the venturi dust collector is discharged into a sedimentation tank together with the dust carried thereby for solid-liquid sedimentation separation, the supernatant separated by the sedimentation tank is overflowed to a circulating water pool for storage, and the water in the circulating water pool is supplied to the venturi dust collector through a first water pump for recycling.

4. A highly efficient and energy saving wet flue gas treatment process according to claim 3, characterized in that, The solid-liquid separation process of the water circulation and treatment step comprises: The liquid formed in the spraying and mist removal process at the bottom of the fine dust removal tower is transported back to the spraying layer of the fine dust removal tower through a second water pump arranged in the tower for recycling, forming a tower circulating system; meanwhile, part of the wastewater in the tower circulating system is discharged into the sedimentation tank in a certain proportion; Fresh production water is supplemented to the circulating water pool and / or the tower circulating system of the fine dust removal tower to maintain the water balance of the system; The concentrated sludge deposited at the bottom of the sedimentation tank is transported to a filter press for dewatering treatment to form sludge cake and is transported out for resource utilization.

5. A highly efficient and energy saving wet flue gas treatment process containing moisture according to claim 2, characterized in that, The at least one mist eliminator of the fine dust removal tower comprises a tube bundle mist eliminator, a plate mist eliminator and a wire mesh mist eliminator arranged in sequence along the flow direction of the flue gas, the flue gas sequentially passes through centrifugal separation of the tube bundle mist eliminator, baffling and impact separation of the plate mist eliminator and interception separation of the wire mesh mist eliminator, and high-efficiency mist removal and dewatering are realized.

6. A highly efficient and energy saving wet flue gas treatment process containing moisture according to claim 5, characterized in that, A plurality of spraying layers are arranged in the fine dust removal tower, the flue gas sequentially passes through the scrubbing liquid curtains formed by the spraying layers from bottom to top, the spacing between the spraying layers is 1.5-2.5 meters, and the operating pressure of the spraying liquid is 0.2-0.6 MPa.

7. A highly efficient and energy saving wet flue gas treatment process according to claim 6, characterized in that, The flue gas velocity at the throat of the Venturi dust collector is controlled within the range of 50-90 m / s during operation, so that the flue gas and the washing liquid will produce violent inertial collisions to capture large dust particles.

8. A highly efficient and energy saving wet flue gas treatment process containing moisture according to claim 1, characterized in that, It also includes intelligent control steps: by monitoring operating parameters through sensors set at key nodes of the system, the central controller dynamically adjusts relevant execution components according to the operating parameters to optimize system energy consumption and operational stability.

9. A highly efficient and energy saving wet flue gas treatment process containing moisture according to claim 8, characterized in that, The intelligent control steps specifically include on-demand spray optimization control: real-time monitoring of the dust concentration of the humid flue gas before entering the Venturi dust collector or after being discharged from the fine dust removal tower; and dynamically adjusting the operating frequency of the second water pump supplying the spray layer of the fine dust removal tower, or adjusting the opening of the regulating valve on the spray pipeline, based on the real-time changes in the dust concentration.

10. A highly efficient and energy saving wet flue gas treatment process containing moisture as claimed in claim 4, wherein, The water circulation and treatment steps also include: fresh production water replenished to the system is supplied to the internal circulation system of the dust removal tower to maintain its water quality and quantity balance.

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