Industrial flue gas multistage collaborative purification and ultra-low emission treatment system

Abstract

The present application relates to the field of industrial flue gas purification and pollution control technology, and discloses a kind of industrial flue gas multistage collaborative purification and ultra-low emission treatment system.The system includes the equalization conditioning unit, the first dry method reaction unit, the intermediate inertial separation unit, the second dry method fine reaction filtering unit, the wet method partition fine washing unit, the condensation water extraction unit and the induced draft emission unit in turn along the flow direction of industrial flue gas, and is provided with ash grading reflux unit, condensate grading reuse unit, clean flue gas reflux branch and by-product collection unit.The solid produced by intermediate inertial separation unit and second dry method fine reaction filtering unit enters ash grading reflux unit and is used for different processing stages respectively, and the condensate produced by condensation water extraction unit is divided into low-conductivity condensate and high-conductivity condensate by condensate grading reuse unit, and is used for equalization conditioning unit and wet method partition fine washing unit respectively.The present application enhances the stability of multistage collaborative purification process, and is conducive to realizing the ultra-low emission of industrial flue gas.

Description

Technical Field

[0001] This invention relates to the field of industrial flue gas purification and pollution control technology, and in particular to a multi-stage synergistic purification and ultra-low emission treatment system for industrial flue gas. Background Technology

[0002] Industrial flue gas typically contains acidic gases, particulate matter, and other pollutants that require synergistic control. As emission control requirements become increasingly stringent, existing industrial flue gas treatment technologies have gradually evolved from single-pollutant treatment to multi-stage purification and multi-pollutant synergistic treatment technologies. A common practice is to combine and arrange units such as dry acid removal, filtration and dust removal, wet absorption, and heat exchange and cooling according to the flue gas flow direction to improve the overall purification capacity.

[0003] For example, publication number CN116651168A discloses a dry multi-pollutant flue gas purification device and method. This prior art includes: setting up a primary dry desulfurization tower, a secondary dry desulfurization tower, and an integrated dust and nitrogen removal device in the flue gas treatment process; introducing a calcium-based absorbent into the primary dry desulfurization tower and a sodium-based absorbent into the secondary dry desulfurization tower; the integrated dust and nitrogen removal device is equipped with a catalytic ceramic filter tube, and the ash outlet of its bottom ash hopper is connected to the primary or secondary dry desulfurization tower via a return material conveying device; simultaneously, this document also discloses installing a temperature measuring instrument at the inlet of the primary dry desulfurization tower and an online flue gas analyzer at its outlet, and adjusting the inlet conditions of the primary dry desulfurization tower by injecting water or steam into the inlet flue and introducing low-temperature flue gas from the downstream section.

[0004] It should be noted that the aforementioned existing technologies have already achieved, to a certain extent, front-end staged deacidification, subsequent filtration and purification, and inlet condition adjustment, and can improve system operation through material return and flue gas recirculation. However, judging from the disclosed content of this existing technology, its material return method mainly involves returning the material in the ash hopper to the primary or secondary dry deacidification tower, which is still a conventional return between treatment stages; at the same time, the focus of this existing technology is mainly on front-end dual absorbent synergistic deacidification and inlet temperature and humidity condition adjustment, without establishing a more refined circulation adaptation structure for the different operating requirements of treatment stages.

[0005] Furthermore, while existing technologies include wet dual-loop treatment structures, such as the dual-loop wet desulfurization structure with upper and lower partitions within the absorption tower disclosed in CN204247062U, and schemes that control the recycling destination using condensate quality indicators, such as the scheme disclosed in CN102849871A that controls condensate and recycles it to different usage points using indicators such as conductivity, existing technologies, specifically for multi-stage synergistic purification systems for industrial flue gas, have not yet developed a system structure capable of precisely adapting the solid return material cycle and liquid recovery cycle simultaneously to the operating characteristics of different treatment stages.

[0006] Therefore, in existing multi-stage industrial flue gas purification systems, there is still a lack of a refined circulation connection mechanism that matches the properties of the circulating media between the front-end dry treatment stage and the downstream wet treatment stage. This results in insufficient adaptability of the circulating media in different treatment stages, thus affecting the overall synergy and operational stability of the multi-stage synergistic purification process. Based on this, how to improve the adaptability of the circulating media utilization between different treatment stages in multi-stage industrial flue gas synergistic purification systems, thereby enhancing the overall synergy and operational stability of the multi-stage purification process, has become a technical problem that needs to be solved in this field. Summary of the Invention

[0007] To overcome the aforementioned technical deficiencies, the present invention aims to provide a multi-stage synergistic purification and ultra-low emission treatment system for industrial flue gas. This application addresses the technical problems of insufficient adaptability of circulating media utilization, low overall synergy, and poor operational stability in existing multi-stage purification processes by incorporating an ash grading reflux unit and a condensate separation and reuse unit within the multi-stage synergistic purification system. This allows different treatment stages to obtain solid ash return and liquid reuse media that match their operational requirements.

[0008] This invention discloses a multi-stage synergistic purification and ultra-low emission treatment system for industrial flue gas, comprising a balanced conditioning unit, a primary dry reaction unit, an intermediate inertial separation unit, a secondary dry fine reaction filtration unit, a wet zone fine washing unit, a condensate extraction unit, and an exhaust fan unit connected sequentially along the flow direction of the industrial flue gas. It also includes an ash classification reflux unit, a condensate separation and reuse unit, a clean flue gas reflux branch, and a by-product collection unit.

[0009] The equalization conditioning unit is equipped with an industrial flue gas inlet, a clean flue gas return inlet, and a low-conductivity condensate atomization inlet; the primary dry reaction unit is equipped with a calcium-based absorbent dosing section.

[0010] The intermediate inertial separation unit is located between the primary dry reaction unit and the secondary dry fine reaction filtration unit, and is equipped with a gas outlet and a solid outlet;

[0011] The two-stage dry fine reaction filtration unit is equipped with a sodium-based absorbent dosing section, a ceramic filtration module, and an ash collection section;

[0012] The ash classification reflux unit is connected to the solid outlet and the ash collection section. The ash classification reflux unit includes a rotor classifier, a first metering feeder and a second metering feeder. The coarse particle outlet of the rotor classifier is connected to the first-stage dry reaction unit via the first metering feeder, and the fine particle outlet of the rotor classifier is connected to the second-stage dry fine reaction filtration unit via the second metering feeder.

[0013] The wet-process zoned fine cleaning unit includes a lower oxidation absorption circulation zone and an upper neutral washing circulation zone connected sequentially from bottom to top. The lower oxidation absorption circulation zone is connected to the lower circulating liquid tank, and the upper neutral washing circulation zone is connected to the upper circulating liquid tank. A gas-liquid separation component is provided between the lower oxidation absorption circulation zone and the upper neutral washing circulation zone. The lower oxidation absorption circulation zone is provided with a lower spray layer, and the upper neutral washing circulation zone is provided with an upper spray layer. An oxidation air distribution component is provided in the lower oxidation absorption circulation zone.

[0014] The condensate extraction unit includes an indirect cooling section, a direct contact condensation section, and a deep demisting section that are connected sequentially along the direction of industrial flue gas flow, as well as a condensate collection section located below the direct contact condensation section and the deep demisting section;

[0015] The condensate separation and recycling unit is connected to the condensate collection section and is equipped with a low conductivity condensate outlet and a high conductivity condensate outlet. The low conductivity condensate outlet is connected to the low conductivity condensate atomization inlet, and the high conductivity condensate outlet is connected to the lower circulating liquid tank through an independent replenishment pipe, and the liquid outlet of the independent replenishment pipe is located below the lower spray layer.

[0016] The intake end of the clean flue gas return branch is connected to the downstream flue of the deep demisting section, and the outlet end of the clean flue gas return branch is connected to the clean flue gas return inlet.

[0017] The lower circulating liquid tank is connected to the solid-liquid separation unit via a side-line solid-liquid separation branch. The clear liquid outlet of the solid-liquid separation unit is connected to the lower circulating liquid tank, and the solid phase outlet of the solid-liquid separation unit is connected to the by-product collection unit.

[0018] Preferably, the equalization conditioning unit includes a mixing chamber, a static mixing section, and a ring-shaped dual-fluid atomizing nozzle group. The clean flue gas return inlet is tangentially connected to the mixing chamber, and the low-conductivity condensate atomizing inlet is connected to the dual-fluid atomizing nozzle group.

[0019] Preferably, the primary dry reaction unit includes a Venturi acceleration section and a capacity expansion reaction section arranged sequentially along the direction of industrial flue gas flow, and the calcium-based absorbent dosing section is located upstream of the throat of the Venturi acceleration section.

[0020] Preferably, the intermediate inertial separation unit is a swirling inertial separator, and the air inlet of the swirling inertial separator is tangentially connected to the expansion reaction section.

[0021] Preferably, the secondary dry fine reaction filtration unit includes a mixing flue and multiple sets of ceramic filter modules arranged in parallel. The sodium-based absorbent dosing section is located on the mixing flue, and each set of ceramic filter modules is provided with an independent ash hopper below it.

[0022] Preferably, the ash grading reflux unit further includes a combined ash hopper, the first inlet of which is connected to the solid outlet, the second inlet of which is connected to the ash collection section, and the rotor classifier is located below the combined ash hopper.

[0023] Preferably, the discharge end of the first metering feeder is connected to the inlet of the expansion reaction section.

[0024] Preferably, the secondary dry fine reaction filtration unit further includes a mixing flue, a sodium-based absorbent dosing section is disposed on the mixing flue, the discharge end of the second metering feeder is connected to the mixing flue, and the connection position between the discharge end of the second metering feeder and the mixing flue is located downstream of the sodium-based absorbent dosing section and upstream of the ceramic filtration module.

[0025] Preferably, the wet-process zoned fine washing unit includes a tower body and a gas-liquid separation component disposed between the lower oxidation absorption circulation zone and the upper neutral washing circulation zone. The gas-liquid separation component is a gas-liquid separation plate, which is provided with vent holes for industrial flue gas to pass upward and a liquid-sealed downcomer leg. The liquid inlet of the liquid-sealed downcomer leg is located on one side of the upper neutral washing circulation zone, and the liquid outlet of the liquid-sealed downcomer leg is located below the liquid level of the lower circulating liquid tank.

[0026] Preferably, the upper circulating liquid tank is provided with an overflow pipe, the outlet end of which is located below the liquid surface of the lower circulating liquid tank, and the oxidation air distribution component is an oxidation air distributor installed below the liquid surface of the lower circulating liquid tank.

[0027] Preferably, the condensate separation and recycling unit includes a conductivity detection chamber, a three-way switching valve, a low-conductivity condensate buffer tank, and a high-conductivity condensate buffer tank connected in sequence. The first outlet of the three-way switching valve is connected to the low-conductivity condensate buffer tank, and the second outlet of the three-way switching valve is connected to the high-conductivity condensate buffer tank. The low-conductivity condensate outlet is the outlet of the low-conductivity condensate buffer tank, and the high-conductivity condensate outlet is the outlet of the high-conductivity condensate buffer tank.

[0028] Preferably, the low conductivity condensate outlet is connected to the low conductivity condensate atomization inlet via a first switching branch and to the upper circulating liquid tank via a second switching branch, while the high conductivity condensate outlet is connected to the lower circulating liquid tank only via an independent replenishment pipe.

[0029] Preferably, the direct contact condensation section is provided with an isolation spray branch that is connected to the upper circulating liquid tank. A one-way replenishment valve is provided between the isolation spray branch and the upper circulating liquid tank. The drain end of the direct contact condensation section and the drain end of the deep demisting section are only connected to the condensate collection section.

[0030] Preferably, the indirect cooling section includes a hot-side heat exchange channel and a cold-side heat exchange channel. The hot-side heat exchange channel is located between the wet-process zoned fine cleaning unit and the direct contact condensation section, and the cold-side heat exchange channel is located on the clean flue gas return branch.

[0031] Preferably, a return fan is provided on the clean flue gas return branch, and the cold side heat exchange channel is located upstream of the return fan.

[0032] Compared with existing technologies, the above technical solution has the following advantages:

[0033] 1. In existing multi-stage industrial flue gas purification systems, there is often a lack of refined circulation and connection mechanisms between the front-end dry treatment stage, the downstream wet treatment stage, and the condensate recovery stage, which are matched with the properties of the media. This easily leads to a relatively crude utilization of returned ash and recovered liquid in different treatment stages, thus affecting the overall stability of the system operation. This invention sets up an ash classification and reflux unit and a condensate separation and reuse unit, so that solid returned ash and condensate are classified and separated according to particle size and conductivity characteristics before being directionally reused to different treatment stages. This achieves the matched utilization of circulating media between different treatment stages, thereby improving the operational stability and synergy of the entire multi-stage collaborative purification system.

[0034] 2. In existing technologies, ash return is usually just a simple recirculation, making it difficult to finely adapt to the reaction conditions of different treatment stages, thus making the pollutant removal process susceptible to load fluctuations. This invention introduces the solids generated by the intermediate inertial separation unit and the secondary dry fine reaction filtration unit into the ash classification and reflux unit, and then sends them back to the primary dry reaction unit and the secondary dry fine reaction filtration unit via a rotor classifier and a metering feeder, respectively. This allows coarse and fine particles to be reused in a more suitable treatment stage, thereby improving the synergistic removal capacity of acidic pollutants and particulate matter between the pre- and post-treatment stages and enhancing the stability of pollutant emission control.

[0035] 3. In existing systems, the utilization efficiency of absorbent and condensate is often insufficient, easily leading to excessively high levels of calcium-based and sodium-based absorbents, as well as fresh water replenishment. This invention improves the reuse efficiency of effective reactive components in the returned ash by setting up a structure that returns coarse particles to the primary dry reaction unit and fine particles to the secondary dry fine reaction filtration unit. Simultaneously, by separating the condensate into low-conductivity and high-conductivity condensates and reusing them respectively in the equalization conditioning unit, the upper circulating liquid tank, and the lower circulating liquid tank, the effective utilization rate of the recovered condensate is improved, thereby reducing absorbent consumption and fresh water replenishment, resulting in better economic efficiency.

[0036] 4. In existing technologies, downstream filtration units are prone to large pressure differential fluctuations during operation, affecting filtration stability and equipment lifespan. This invention addresses this by feeding fine particles via a second metering feeder into a mixing flue located downstream of the sodium-based absorbent dosing section and upstream of the ceramic filter module. This allows the fine particles to participate in subsequent fine reactions within a more favorable window area, reducing ineffective ash accumulation and localized load fluctuations. Consequently, it reduces pressure differential fluctuations in the secondary dry fine reaction filtration unit, improving the stability of subsequent fine reactions and the filtration process.

[0037] 5. In existing wet scrubbing systems, cross-contamination, backmixing, or convergence of liquid properties easily occur between the upper and lower liquid phases, hindering the effective functioning of different treatment zones. This invention addresses this by incorporating a gas-liquid separator, a liquid-sealed downcomer, an upper circulating liquid tank, a lower circulating liquid tank, and an oxidation air distribution assembly. This allows the upper neutral scrubbing circulation zone and the lower oxidation absorption circulation zone to maintain necessary liquid connectivity while retaining their distinct liquid phase environments. This enhances the wet scrubbing unit's ability to process industrial flue gas in its respective zones and improves overall treatment stability.

[0038] 6. In existing technologies, condensate is often collected and reused uniformly, which can easily allow high-salt liquids to enter unsuitable treatment areas, thus affecting conditioning effects or circulating fluid stability. This invention, by incorporating a conductivity detection chamber, a three-way switching valve, a low-conductivity condensate buffer tank, and a high-conductivity condensate buffer tank, enables the condensate to be separated according to conductivity and reused in different functional locations. This reduces the risk of unsuitable liquids entering sensitive treatment stages, lowers circulating fluid conductivity fluctuations, and improves the controllability of the liquid phase system operation.

[0039] 7. In existing technologies, clean flue gas recirculation and cooling heat exchange are often set up separately, resulting in limited system energy utilization efficiency. This invention uses the clean flue gas recirculation branch as a cold-side heat exchange channel for the indirect cooling section, allowing the clean flue gas to participate in the heat exchange process before recirculating to the equalization conditioning unit. This improves the heat utilization efficiency while improving the front-end conditioning conditions, reduces the risk of condensation in the recirculation branch, and enhances the overall economic efficiency of the system.

[0040] 8. Existing technologies are prone to parameter imbalances, emission fluctuations, or circulation system instability under load fluctuations or abnormal operating conditions. This invention not only constructs a multi-stage collaborative purification system structure but also incorporates linkage control logic corresponding to emission indicators, differential pressure, and condensate conductivity, as well as startup steps and abnormal operating condition handling logic. This ensures that the invention maintains good operational adaptability and engineering feasibility under different industrial flue gas load conditions. Attached Figure Description

[0041] Figure 1 A schematic diagram of the overall structure of a multi-stage synergistic purification and ultra-low emission treatment system for industrial flue gas;

[0042] Figure 2 This is a schematic diagram of the gray grading reflow unit structure and its connection relationships.

[0043] Figure 3 This is a schematic diagram of the wet-process zoned fine washing unit structure;

[0044] Figure 4 A schematic diagram showing the connection relationship between the condensate separation and recycling unit and the clean flue gas return branch;

[0045] Figure 5 The curve showing the change in sulfur dioxide mass concentration during the stable operation phase;

[0046] Figure 6 The pressure difference change curve of the two-stage dry fine reaction filtration unit;

[0047] Figure 7 The curve showing the change in conductivity of the lower circulating liquid tank;

[0048] Figure 8 This is a comparison chart of key performance indicators. Detailed Implementation

[0049] The following is combined with Figures 1 to 8 The present invention will be further described in detail below. This embodiment is based on a processing scale of... Taking an industrial flue gas treatment device as an example, the industrial flue gas being treated originates from acidic industrial tail gas under continuous combustion conditions. The temperature of the industrial flue gas entering the system is controlled at approximately 172℃, and the sulfur dioxide concentration is controlled at [missing information]. The mass concentration of hydrogen chloride is controlled at approximately [value missing]. The particulate matter concentration is controlled at around [a certain level]. The industrial flue gas enters the equalization conditioning unit through the industrial flue gas inlet. The equalization conditioning unit is equipped with a mixing chamber, a static mixing section, and a ring-shaped dual-fluid atomizing nozzle group. The clean flue gas return inlet is tangentially connected to the mixing chamber, and the low-conductivity condensate atomizing inlet is connected to the dual-fluid atomizing nozzle group. This allows the clean flue gas returned from the clean flue gas return branch to be uniformly mixed with the low-conductivity condensate injected through the dual-fluid atomizing nozzle group in the mixing chamber and the static mixing section. This ensures that the temperature of the industrial flue gas before entering the first-stage dry reaction unit is stably controlled within the range of 115℃ to 120℃, and the relative humidity of the industrial flue gas is stably controlled within a range more suitable for the reaction of the calcium-based absorbent.

[0050] In this embodiment, to facilitate the distinction between "low-conductivity condensate" and "high-conductivity condensate," the conductivity of the condensate is uniformly measured using an online conductivity meter at 25°C. For sample verification, an offline measurement can be performed using a benchtop conductivity meter at a constant temperature of 25°C, with a verification standard of no more than 5% deviation between online and offline data. To facilitate the distinction between "coarse particles" and "fine particles," the particle size in the ash grading reflux unit is uniformly characterized using aerodynamic equivalent particle size and measured using a laser particle size analyzer. Before measurement, the collected samples are subjected to constant weight treatment and dry dispersion injection to reduce the impact of agglomeration on the measurement results.

[0051] The industrial flue gas, after equalization and conditioning, enters the primary dry reaction unit, which includes a Venturi acceleration section and an expansion reaction section arranged sequentially along the flow direction of the industrial flue gas. The calcium-based absorbent dosing section is located upstream of the throat of the Venturi acceleration section. In this embodiment, the calcium-based absorbent is calcium hydroxide powder, and the dosing mass flow rate is controlled at approximately 1.00 t / h. After passing through the Venturi acceleration section, the flow velocity of the industrial flue gas increases, and the calcium hydroxide powder rapidly disperses in the high-velocity region and undergoes a primary reaction with the acidic gas. Subsequently, it enters the expansion reaction section to continue completing the gas-solid reaction and residence reaction. To balance the reaction residence time and system pressure drop, the cross-section of the throat of the Venturi acceleration section can be set to 40%–60% of the inlet cross-section, and the length of the expansion reaction section can be set to 3500 mm–4200 mm. This setting ensures rapid dispersion of the calcium-based absorbent in the initial stage while reserving a stable access space for subsequent solid phase return ash reuse.

[0052] The industrial flue gas, after being treated by the primary dry reaction unit, enters tangentially into the intermediate inertial separation unit, which is a cyclone inertial separator. Within the cyclone inertial separator, a rotating flow field is formed. Coarse particles descend along the separator wall and are discharged through the solid outlet; fine particles and gas are discharged through the gas outlet and enter the secondary dry fine reaction filtration unit. This setup reduces the particle load on the subsequent ceramic filtration module and allows for the early separation of coarse particles more suitable for return to the primary dry reaction unit for reprocessing, thus creating conditions for the dual-path ash return in the subsequent ash classification and recirculation unit.

[0053] The two-stage dry fine reaction filtration unit includes a mixing flue, multiple sets of parallel-connected ceramic filter modules, a sodium-based absorbent dosing section, and an ash collection section. The sodium-based absorbent dosing section is located on the mixing flue, and each set of ceramic filter modules has an independent ash hopper below it. These independent ash hoppers collectively constitute the ash collection section. After the industrial flue gas enters the mixing flue through the outlet of the cyclone inertial separator, the sodium-based absorbent is injected into the mixing flue from the sodium-based absorbent dosing section to further neutralize residual acidic gases in the industrial flue gas. Subsequently, the industrial flue gas enters the multiple sets of parallel-connected ceramic filter modules for fine particle interception and further fine treatment. The ceramic filter modules can use high-temperature resistant and corrosion-resistant ceramic filter bodies. The parallel arrangement of the modules helps reduce local flow velocity fluctuations and decrease system pressure differential. Simultaneously, each set of independent ash hoppers can discharge ash separately before converging into the ash collection section, facilitating subsequent unified classification and quantitative return.

[0054] like Figure 2 As shown, the ash grading reflux unit is connected to the solid outlet of the intermediate inertial separation unit and the ash collection section of the secondary dry fine reaction filtration unit. The ash grading reflux unit includes a combined ash hopper, a rotor classifier, a first metering feeder, and a second metering feeder. The first inlet of the combined ash hopper is connected to the solid outlet, and the second inlet of the combined ash hopper is connected to the ash collection section. The rotor classifier is located below the combined ash hopper. Coarse particles from the cyclone inertial separator and fine particles from the ash collection section are first homogenized in the combined ash hopper, and then classified by the rotor classifier. In this embodiment, particles with an aerodynamic equivalent particle size greater than 45 μm are defined as coarse particles, and particles with an aerodynamic equivalent particle size not greater than 45 μm are defined as fine particles.

[0055] It should be noted that the 45μm threshold was determined through preliminary experimental comparisons: when the threshold is below 35μm, the proportion of fine particles entering the primary dry reaction unit is too high, leading to a decrease in the dispersion utilization efficiency in the primary dry reaction unit; when the threshold is above 60μm, the proportion of fine particles entering the window area of ​​the secondary dry fine reaction filtration unit is insufficient, making it difficult to demonstrate the fine reaction advantage of the secondary dry fine reaction filtration unit. Therefore, it is preferable to set the threshold around 45μm. Furthermore, in the preliminary experiments, the mass concentration of emitted sulfur dioxide, the pressure difference fluctuation amplitude of the secondary dry fine reaction filtration unit, and the sodium-based absorbent consumption were compared under three particle size thresholds of 35μm, 45μm, and 60μm, respectively. The results show that when 45μm is used as the boundary between coarse and fine particles, the comprehensive balance effect of the three indicators is optimal. The coarse particle outlet of the rotor classifier is connected to the primary dry reaction unit via a first metering feeder, and the discharge end of the first metering feeder is connected to the inlet of the expansion reaction section. The fine particle outlet of the rotor classifier is connected to the secondary dry fine reaction filtration unit via a second metering feeder, and the discharge end of the second metering feeder is connected to the mixing flue. The connection point between the discharge end of the second metering feeder and the mixing flue is located downstream of the sodium-based absorbent addition section and upstream of the ceramic filter module. To further clarify this connection point, in this embodiment, the axial distance between the connection point of the discharge end of the second metering feeder and the mixing flue and the sodium-based absorbent addition section can be set to 0.5m to 1.5m, preferably 0.9m to 1.2m; the axial distance between this connection point and the inlet of the foremost ceramic filter module can be set to 0.8m to 2.0m, preferably 1.1m to 1.6m. Thus, coarse particles are sent back to the inlet of the expansion reaction section in the primary dry reaction unit to participate in a second reaction, while fine particles are sent to the window area where the sodium-based absorbent has been added but has not yet entered the ceramic filter module, forming a utilization path more suitable for the fine reaction and filtration of the secondary dry fine reaction filtration unit. The first and second metering feeders are preferably variable frequency screw feeders to dynamically adjust the return flow rates of coarse and fine particles according to operating load and emission fluctuations.

[0056] After leaving the secondary dry fine reaction and filtration unit, the industrial flue gas enters the wet zone fine scrubbing unit. For example... Figure 3As shown, the wet-process zoned fine cleaning unit includes a tower body, a lower oxidation absorption circulation zone, an upper neutral scrubbing circulation zone, a lower circulating liquid tank, an upper circulating liquid tank, a lower spray layer, an upper spray layer, and a gas-liquid separation component disposed between the lower oxidation absorption circulation zone and the upper neutral scrubbing circulation zone. The gas-liquid separation component is a gas-liquid separation plate, which has vents for industrial flue gas to pass upward and liquid-sealed downcomer legs. The inlet of the liquid-sealed downcomer legs is located on the side of the upper neutral scrubbing circulation zone, and the outlet of the liquid-sealed downcomer legs is located below the liquid surface of the lower circulating liquid tank. After entering from the lower part of the tower body, the industrial flue gas first contacts the circulating liquid sprayed from the lower spray layer in the lower oxidation absorption circulation zone, completing the main absorption and oxidation reactions. Then, it enters the upper neutral scrubbing circulation zone through the vents on the gas-liquid separation plate, where the neutral scrubbing liquid sprayed from the upper spray layer further cleans the residual acidic components and soluble salt spray in the industrial flue gas. The combination of the gas-liquid separator and the liquid seal downcomer allows the upper circulating liquid to fall back to the lower circulating liquid tank in a controlled manner, while suppressing the lower circulating liquid from flowing back to the upper neutral washing circulation zone due to bubbling, turbulence, or liquid surface fluctuations, thereby maintaining the differentiated operating state of the upper and lower circulating liquid systems.

[0057] In this embodiment, an oxidation air distribution component is installed in the lower oxidation absorption circulation zone. This component is an oxidation air distributor positioned below the liquid surface of the lower circulating liquid tank to continuously blow air into the lower circulating liquid, promoting the conversion of sulfite to sulfate. The upper circulating liquid tank is equipped with an overflow pipe, the outlet of which is located below the liquid surface of the lower circulating liquid tank. This overflow pipe maintains the liquid level in the upper circulating liquid tank while smoothly guiding a portion of the upper circulating liquid into the lower circulating liquid tank, preventing surface disturbance caused by free fall. The lower circulating liquid tank is connected to a solid-liquid separation unit via a side-line solid-liquid separation branch. The solid-liquid separation unit can be a combination of a hydrocyclone and a filter press. The filter press filtrate outlet returns to the lower circulating liquid tank, while the filter cake outlet enters a by-product collection unit to discharge salt-rich solids and reaction by-products, maintaining a controllable solid content and ion balance in the lower circulating liquid.

[0058] The industrial flue gas, after being treated by the wet scrubbing unit, enters the condensate extraction unit. The condensate extraction unit includes an indirect cooling section, a direct contact condensation section, and a deep demisting section, sequentially connected along the flow direction of the industrial flue gas, as well as a condensate collection section located below the direct contact condensation section and the deep demisting section. In the indirect cooling section, the industrial flue gas first undergoes heat exchange with the cold-side medium, resulting in an initial temperature decrease. Subsequently, in the direct contact condensation section, it comes into direct contact with the spray liquid, further condensing out condensate. It then enters the deep demisting section to remove carried droplets, forming purified flue gas at a lower temperature. The direct contact condensation section is equipped with an isolation spray branch connected to the upper circulating liquid tank. A one-way replenishment valve is installed between the isolation spray branch and the upper circulating liquid tank. The drain ends of both the direct contact condensation section and the deep demisting section are only connected to the condensate collection section. This allows the upper circulating liquid to participate in the operation of the direct contact condensation section as an isolation spray liquid, while preventing the condensate formed in the direct contact condensation section and the deep demisting section from flowing back into the upper circulating liquid tank and altering the properties of the upper circulating liquid.

[0059] like Figure 4As shown, the condensate collected by the condensate collection unit enters the condensate separation and reuse unit. The condensate separation and reuse unit includes a conductivity detection chamber, a three-way switching valve, a low-conductivity condensate buffer tank, and a high-conductivity condensate buffer tank, connected in sequence. The first outlet of the three-way switching valve is connected to the low-conductivity condensate buffer tank, and the second outlet of the three-way switching valve is connected to the high-conductivity condensate buffer tank. The low-conductivity condensate outlet is the outlet of the low-conductivity condensate buffer tank, and the high-conductivity condensate outlet is the outlet of the high-conductivity condensate buffer tank. In this embodiment, condensate with a conductivity of not more than 1500 μS / cm is defined as low-conductivity condensate, and condensate with a conductivity greater than 1500 μS / cm is defined as high-conductivity condensate. It should be noted that the 1500 μS / cm threshold was also determined through preliminary experimental comparisons: when the threshold is below 1100 μS / cm, the proportion of low-conductivity condensate that can be reused in the equalization conditioning unit and the upper circulating liquid tank is low, resulting in a decrease in the recovery rate; when the threshold is above 1900 μS / cm, the salt content in the liquid entering the upper circulating liquid tank or the equalization conditioning unit increases significantly, which is not conducive to the long-term stability of the system. Therefore, 1500 μS / cm is preferred as the separation threshold. Furthermore, in the preliminary experiments, the fresh water replenishment volume, the conductivity fluctuation range of the lower circulating liquid tank, and the temperature stability of the industrial flue gas at the outlet of the equalization conditioning unit were compared under the three conductivity thresholds of 1100 μS / cm, 1500 μS / cm, and 1900 μS / cm. The results show that when 1500 μS / cm is used as the separation threshold, the overall effect of recovery rate and system stability is better. The low-conductivity condensate outlet is connected to the low-conductivity condensate atomization inlet via a first switching branch, and to the upper circulating liquid tank via a second switching branch. The high-conductivity condensate outlet is connected to the lower circulating liquid tank only via an independent replenishment pipe, with the outlet end of the independent replenishment pipe located below the lower spray layer. Therefore, the higher-quality low-conductivity condensate is preferentially recycled to the equalization and conditioning unit or the upper neutral washing circulation zone, while the relatively lower-quality high-conductivity condensate is restricted to recycling to the lower circulating liquid tank, thus achieving compatibility between the condensate and the operational requirements of different treatment stages.

[0060] The downstream flue of the deep demisting section is connected to the clean flue gas return branch, and the outlet of the clean flue gas return branch is connected to the clean flue gas return inlet of the equalization conditioning unit. The indirect cooling section includes a hot-side heat exchange channel and a cold-side heat exchange channel, wherein the hot-side heat exchange channel is located between the wet zoning fine washing unit and the direct contact condensation section, and the cold-side heat exchange channel is located on the clean flue gas return branch. A return fan is installed on the clean flue gas return branch, and the cold-side heat exchange channel is located upstream of the return fan. Furthermore, to make this part of the structure more feasible, in this embodiment, the indirect cooling section preferably adopts a plate heat exchange structure or a shell-and-tube heat exchange structure; when adopting a shell-and-tube heat exchange structure, the hot-side heat exchange channel and the cold-side heat exchange channel preferably adopt a counter-current heat exchange method to improve the heat exchange efficiency per unit heat exchange area. The inlet temperature of the industrial flue gas on the hot side can be 60℃~75℃, and the outlet temperature can be reduced to 45℃~55℃. The inlet temperature of the clean flue gas in the cold side heat exchange channel can be 35℃~45℃, which can be raised to 45℃~55℃ after heat exchange. With this structure, the clean flue gas first undertakes the cold-side heat exchange function of the indirect cooling section in the cold-side heat exchange channel before returning to the equalization conditioning unit. This can reduce the temperature of the industrial flue gas before entering the direct contact condensation section and increase the temperature of the returning clean flue gas, thereby reducing the risk of condensation in the return branch and improving the system's heat utilization efficiency.

[0061] Furthermore, to further clarify the relative arrangement of the independent replenishment pipes, in this embodiment, the horizontal projection distance between the center of the outlet end of the independent replenishment pipe and the center of the oxidation air distribution component in the lower circulating liquid tank can be set to 0.2m to 1.2m, preferably 0.4m to 0.8m; the height difference between the center of the outlet end of the independent replenishment pipe and the upper surface of the oxidation air distribution component can be set to 0.1m to 0.6m, preferably 0.2m to 0.4m. Through the above relative arrangement, the high-conductivity condensate can quickly enter the area of ​​significant bubbling and mixing after entering the lower circulating liquid tank, thereby reducing the phenomenon of local salt enrichment.

[0062] This embodiment further illustrates the system startup steps as follows: Upon startup, the induced draft exhaust unit is first activated to establish a basic negative pressure in the entire system. Then, the return fan on the clean flue gas return branch is activated to establish a minimum return flow rate. Next, the equalization conditioning unit is activated, the dual-fluid atomizing nozzle group is turned on, and low-conductivity condensate is gradually introduced. After the industrial flue gas temperature at the outlet of the equalization conditioning unit stabilizes within a preset range, the calcium-based absorbent dosing section of the primary dry reaction unit, the intermediate inertial separation unit, the sodium-based absorbent dosing section of the secondary dry fine reaction filtration unit, and the ceramic filter module are activated sequentially. Subsequently, the liquid levels of the lower and upper circulating liquid tanks in the wet zone fine washing unit are established, and the oxidation air distribution components and upper and lower spray layers are activated. Finally, the condensate extraction unit and the condensate separation and recycling unit are activated, and low-conductivity condensate circuits and high-conductivity condensate circuits are established sequentially based on conductivity detection results. Through the above startup sequence, sudden changes in temperature, humidity, pressure difference, and liquid level within the system can be reduced, shortening the time for the entire system to reach stable operating conditions.

[0063] In a specific industrial application, the initial temperature of the industrial flue gas entering the system is controlled between 165℃ and 180℃, and the initial sulfur dioxide concentration is controlled at [specific value missing]. Between, the mass concentration of hydrogen chloride is controlled at Between, the particulate matter mass concentration is controlled at The equilibrium conditioning unit maintains an outlet temperature of approximately 115℃. The primary dry reaction unit primarily handles the initial reaction involving the calcium-based absorbent. The intermediate inertial separation unit first separates coarse particles. The secondary dry fine reaction and filtration unit, with the participation of a sodium-based absorbent, completes subsequent fine reactions and ceramic filtration. The wet zoned fine washing unit achieves enhanced absorption in the lower section and neutral cleaning in the upper section through upper and lower zoned treatment. The condensate extraction unit further extracts moisture from the industrial flue gas and forms condensate. The condensate recycling unit returns the condensate to different treatment stages based on its conductivity. After continuous operation, the above system can form a stable dual-phase adaptive cycle of solid and liquid phases.

[0064] It should be noted that two additional sets of optional operating parameters are provided. The first set is for lower load conditions, where the industrial flue gas treatment capacity can be set to... The inlet industrial flue gas temperature can be set to approximately 168℃, and the sulfur dioxide concentration can be set to... The mass flow rate of calcium-based absorbent can be set to 0.85 t / h, and the mass flow rate of sodium-based absorbent can be set to 0.18 t / h. The conductivity threshold for condensate remains at 1500 μS / cm. The second group represents a higher load condition, where the industrial flue gas treatment capacity can be set to... The inlet industrial flue gas temperature can be set to approximately 178℃, and the sulfur dioxide concentration can be set to... The mass flow rate of the calcium-based absorbent can be set to 1.25 t / h, and the mass flow rate of the sodium-based absorbent can be set to 0.33 t / h. The preferred threshold for separating coarse and fine particles in the rotor classifier is still 45 μm. Trial operation shows that under both lower and higher load conditions, the system of this invention can still form a stable ash classification reflux and condensate separation and reuse path, indicating that this invention is not only applicable to single-point conditions.

[0065] The following is a further implementation method two. Implementation method two is basically the same as implementation method one in terms of overall structure, connection relationships, components shown in the accompanying drawings, and operating logic. The difference lies in that implementation method two uses a lower load condition as the main operating condition, and the industrial flue gas treatment capacity is... The inlet industrial flue gas temperature is approximately 168℃, and the inlet sulfur dioxide concentration is... The calcium-based absorbent was added at a mass flow rate of 0.85 t / h, and the sodium-based absorbent at a mass flow rate of 0.18 t / h. The industrial flue gas temperature at the outlet of the equalization conditioning unit was controlled within the range of 112℃ to 118℃. In Implementation Method Two, the threshold for separating coarse and fine particles in the rotor classifier remained at 45 μm, and the threshold for separating condensate conductivity remained at 1500 μS / cm. Under this lower load condition, the return flow rate of the clean flue gas recirculation branch could be appropriately reduced, the level control range of the lower and upper circulating liquid tanks could be correspondingly reduced, and the operating frequency of the side-line solid-liquid separation branch could also be appropriately reduced. Continuous operation results of Implementation Method Two showed that after 72 hours of continuous operation and entering a stable operation phase in the last 48 hours, the sulfur dioxide emission concentration could be stably controlled within a certain range. Within the specified range, the pressure difference fluctuation of the secondary dry fine reaction filtration unit can be controlled within the range of 300Pa to 380Pa, the conductivity fluctuation of the lower circulating liquid tank can be controlled within the range of 7.0% to 8.5%, and the fresh water replenishment can be maintained within the range of 1.45t / h to 1.75t / h, indicating that the system of the present invention also has good adaptability and operational stability under low load conditions. Furthermore, in Embodiment 2, the consumption of calcium-based absorbent can be controlled within the range of 0.82t / h to 0.90t / h, and the consumption of sodium-based absorbent can be controlled within the range of 0.16t / h to 0.20t / h, indicating that when the industrial flue gas treatment volume decreases, the system of the present invention can still maintain the synergistic effect of the solid phase reflux path and the condensate fractionation and reuse path.

[0066] To more intuitively illustrate the technical effects of the present invention, comparative experiments are conducted on the following embodiments and comparative examples. The comparative example uses the existing technology's process concept to construct the system, employing a two-stage dry deacidification process followed by ceramic filtration, material return, and a clean flue gas recirculation temperature control structure. However, it does not include a rotor classifier combined with a first and second metering feeder to form a graded quantitative ash return structure, nor does it include a condensate recycling unit; instead, the condensate is uniformly returned to the lower circulating liquid tank. Apart from the above differences, the embodiments and comparative examples use the same industrial flue gas source, the same industrial flue gas treatment volume, the same inlet industrial flue gas pollutant concentration range, the same operating time, and the same detection methods to maintain single and comparable comparison conditions. After startup, the device undergoes 24 hours of preheating and stabilization, followed by continuous operation for 72 hours. During the subsequent 48 hours of stable operation, samples are taken and recorded every hour for the emission sulfur dioxide mass concentration, the pressure difference of the secondary dry fine reaction filtration unit, the conductivity of the lower circulating liquid tank, and the consumption of calcium-based absorbent, sodium-based absorbent, and fresh water replenishment. The average value during the subsequent 48-hour stable operation phase is presented in Table 2.

[0067] The determination methods for each detection index in this embodiment are further explained as follows: the mass concentration of sulfur dioxide emissions is continuously measured using an online industrial flue gas analyzer, and periodically calibrated using a portable industrial flue gas analyzer; the mass concentration of hydrogen chloride is determined using isokinetic sampling followed by ion chromatography; the mass concentration of particulate matter is determined using the gravimetric method; the pressure difference of the secondary dry reaction filtration unit is measured online using a differential pressure transmitter; the conductivity of the lower circulating liquid tank is measured using an online conductivity meter; the unit consumption of calcium-based absorbent and sodium-based absorbent is calculated based on the cumulative feed rate of the feeder and the corresponding running time; the fresh water replenishment is recorded by a mass flow meter on the water replenishment pipeline. As a further explanation, the examples and comparative examples are each independently repeated 3 times. The data listed in Table 2 are the average values ​​of the results of the 3 independent runs, and the relative deviation of each test result is controlled within 10%.

[0068] Main operating conditions table 1

[0069]

[0070] Table 2 of the main test results

[0071]

[0072] Depend on Figure 5 It can be seen that the sulfur dioxide emission concentration of the embodiment during the stable operation phase is generally lower than that of the comparative example, and the fluctuation range is smaller. This indicates that through the coordinated setting of graded quantitative ash return and differentiated reuse, the reaction and circulation state among the primary dry reaction unit, the secondary dry fine reaction and filtration unit, and the wet zoned fine washing unit is more stable. Figure 6It can be seen that the pressure difference change in the secondary dry fine reaction filtration unit of the embodiment is significantly lower than that of the comparative example, indicating that the precise ingress position of fine particles in the mixing flue helps improve the subsequent fine reaction and filtration conditions of the secondary dry fine reaction filtration unit. Figure 7 It can be seen that the conductivity fluctuation of the lower circulating liquid tank in the embodiment is significantly smaller than that in the comparative example. This indicates that the path design, which limits the reuse of high-conductivity condensate to the lower circulating liquid tank while reusing low-conductivity condensate to the equalization and conditioning unit and the upper circulating liquid tank respectively, helps maintain the stability of the upper and lower liquid phase systems. Figure 8 It can be seen that the example is superior to the comparative example in terms of calcium-based absorbent consumption, sodium-based absorbent consumption, and fresh water replenishment.

[0073] To further illustrate the quantification effect of the present invention, specific calculation examples are given below.

[0074] Example 1: Calculation of the reduction in the unit consumption of calcium-based absorbent. Let the unit consumption of the calcium-based absorbent in the comparative example be... The calcium-based absorbent in the embodiment has a unit consumption of [missing information]. The calcium-based absorbent's unit consumption decreased by [percentage missing]. The reduction in the unit consumption of calcium-based absorbent is calculated using formula (1):

[0075]

[0076] In the formula, The consumption of calcium-based absorbent in the comparative proportion is expressed in t / h. The unit consumption of the calcium-based absorbent in the embodiment is expressed in t / h; This indicates the percentage reduction in calcium-based absorbent consumption. Substitute the data from Table 2 and take... , ,but:

[0077]

[0078] Therefore, the system of the present invention reduces the consumption of calcium-based absorbent by 8.26%.

[0079] Example 2: Calculation of the reduction in sodium-based absorbent consumption. Let the sodium-based absorbent consumption in the comparative example be... The sodium-based absorbent consumption in the example is... The sodium-based absorbent consumption decreased by [percentage missing]. The reduction in sodium-based absorbent consumption is calculated using equation (2):

[0080]

[0081] In the formula, The consumption of sodium-based absorbent in the comparative proportion is expressed in t / h. The sodium-based absorbent consumption in the examples is expressed in t / h. This indicates the percentage reduction in sodium-based absorbent consumption. Substitute the data from Table 2 and take... , ,but:

[0082]

[0083] As can be seen, the system of the present invention reduces the consumption of sodium-based absorbent by 27.59%.

[0084] Example 3: Calculation of the decrease in fresh water replenishment. Let the fresh water replenishment for the comparative example be... The fresh water replenishment amount in the example is The decrease in fresh water replenishment was The decrease in fresh water replenishment is calculated using formula (3):

[0085]

[0086] In the formula, This indicates the proportion of fresh water replenishment, expressed in t / h. This indicates the amount of fresh water replenished in the embodiment, in t / h. This indicates the percentage decrease in fresh water replenishment. Substitute the data from Table 2 and take... , ,but:

[0087]

[0088] This indicates that by reusing the condensate in different grades, the system of this invention reduces the amount of fresh water replenished by 32.00%.

[0089] Example 4: Calculation of the reduction in pressure difference fluctuation in a two-stage dry reactive filtration unit. Assume the pressure difference fluctuation of the comparative example is... The differential pressure fluctuation range in the example is: The pressure differential fluctuation range decreased by The decrease in differential pressure fluctuation amplitude is calculated using equation (4):

[0090]

[0091] In the formula, This indicates the amplitude of the differential pressure fluctuation, in Pa. This indicates the differential pressure fluctuation range in the example, in Pa. This indicates the percentage decrease in differential pressure fluctuation. Substitute the data from Table 2 and take... , ,but:

[0092]

[0093] This demonstrates that the system of the present invention can significantly reduce the pressure difference fluctuation of the two-stage dry fine reaction filtration unit.

[0094] Example 5: Calculation of the decrease in conductivity fluctuation amplitude in the lower circulating fluid tank. Assume the conductivity fluctuation amplitude of the comparative example is... The conductivity fluctuation range in the example is as follows: The decrease in conductivity fluctuation range was The decrease in conductivity fluctuation amplitude is calculated using equation (5):

[0095]

[0096] In the formula, This indicates the amplitude of the comparative conductivity fluctuation; This indicates the amplitude of conductivity fluctuation in the embodiment; This indicates the percentage decrease in conductivity fluctuation. Substitute the data from Table 2 and take... , ,but:

[0097]

[0098] This demonstrates that the system of the present invention also has a significant advantage in terms of the stability of the conductivity of the lower circulating liquid tank.

[0099] To further illustrate that the system of the present invention does not rely solely on a static structure for operation, this embodiment also describes its control logic. During continuous operation, when the industrial flue gas online analyzer detects that the mass concentration of emitted sulfur dioxide is higher than the preset control value, the feeding frequency of the second metering feeder is increased first, and the dosage of the sodium-based absorbent in the dosing section is increased slightly simultaneously. If the mass concentration of emitted sulfur dioxide remains higher than the preset control value after adjustment, the feeding frequency of the first metering feeder and the dosage of the calcium-based absorbent in the dosing section are further increased. When the pressure difference of the secondary dry fine reaction filtration unit increases and reaches the preset fluctuation threshold, the feeding frequency of the second metering feeder is reduced first, and the cleaning rhythm of the ceramic filter module is adjusted according to the pressure difference change trend. When the conductivity detection chamber detects that the conductivity of the condensate is higher than the separation threshold, the three-way switching valve switches to the high conductivity condensate buffer tank side, allowing the condensate to enter the independent replenishment pipe through the high conductivity condensate outlet. When the detected conductivity is lower than the separation threshold, the three-way switching valve switches to the low conductivity condensate buffer tank side, allowing the condensate to enter the first switching branch or the second switching branch through the low conductivity condensate outlet. Furthermore, when the conductivity fluctuation of the lower circulating liquid tank exceeds the preset fluctuation limit, the replenishment ratio of the high conductivity condensate outlet through the independent replenishment pipe is preferentially reduced, and the processing frequency of the side-line solid-liquid separation branch is increased. When the industrial flue gas temperature at the outlet of the equalization conditioning unit deviates from the preset range, the target temperature range is restored by adjusting the frequency of the return fan and the amount of low conductivity condensate atomized and reused in the first switching branch. Through the above control logic, the system of this invention can dynamically adjust the solid phase reflux and liquid phase reuse paths according to emission indicators, differential pressure, and condensate conductivity, thereby further improving the overall stability of the multi-stage synergistic purification process.

[0100] Furthermore, to demonstrate the feasibility and controllability of the system under abnormal operating conditions, this embodiment describes the following abnormal operating condition handling logic: When the conductivity detection chamber detects that the conductivity of the condensate is higher than the separation threshold for 2 consecutive hours, the three-way switching valve remains switched to the high conductivity condensate buffer tank side, and the opening of the first switching branch is restricted to prevent the high conductivity condensate from entering the equalization conditioning unit; when the pressure difference of the secondary dry fine reaction filtration unit is higher than the preset pressure difference upper limit for 1 consecutive hour, the speed of the second metering feeder is reduced, and the cleaning frequency of the ceramic filter module is increased simultaneously, and the dosage of sodium-based absorbent is reduced briefly if necessary; when the liquid level of the upper circulating liquid tank is too high or fluctuates abnormally, the replenishment amount of the second switching branch is restricted, and the liquid level is maintained through the overflow pipe; when the liquid level of the lower circulating liquid tank is too high and the conductivity of the condensate continues to rise, the extraction frequency of the side solid-liquid separation branch is increased, and the replenishment amount of the high conductivity condensate outlet is restricted. Through the above abnormal operating condition handling logic, the system can still maintain controllable operation when the operating conditions deviate from the normal range.

[0101] Combination Figures 5 to 8As can be seen from the above calculation results, this invention, by simultaneously setting up an ash grading reflux structure and a condensate separation and reuse structure in the same multi-stage collaborative purification chain, allows different treatment stages to obtain solid ash and condensate that match their operational requirements. Coarse particles enter the expansion reaction section inlet through the first metering feeder, enabling more efficient reuse in the gas-solid reaction stage of the primary dry reaction unit; fine particles enter the mixing flue downstream of the sodium-based absorbent addition section and upstream of the ceramic filter module through the second metering feeder, which is beneficial to improving the utilization efficiency of subsequent fine reaction and filtration stages in the secondary dry fine reaction filtration unit. Low-conductivity condensate is preferentially reused in the equalization conditioning unit and the upper neutral washing system, while high-conductivity condensate is restricted to entering the lower circulating liquid tank, ensuring that the condensate usage path matches the operational attributes of each treatment stage within the system. Therefore, this invention not only reduces absorbent consumption and water replenishment but also improves the operational stability of the secondary dry fine reaction filtration unit and the wet zone fine washing unit.

[0102] Furthermore, the upper and lower partitioned wet process structure, formed by a gas-liquid separator and a liquid-sealed downcomer, ensures that the upper neutral washing circulation zone and the lower oxidation absorption circulation zone maintain the necessary liquid reflux while preserving the differences in the properties of their respective circulating liquids. The structure employing a cold-side heat exchange channel in the indirect cooling section arranged on the clean flue gas return branch allows the clean flue gas to perform indirect cooling before recirculation, which is beneficial for improving energy utilization efficiency and reducing the risk of branch condensation. In summary, this implementation method enables precise adaptation and circulation of solid and liquid media within the same multi-stage collaborative purification system, thereby improving the synergy between different treatment stages and the overall operational stability.

[0103] Finally, the compatibility of materials needs to be specified. To ensure long-term operation of the system under acidic industrial flue gas conditions, the equalization conditioning unit, primary dry reaction unit, expansion reaction section, mixing flue, wet zone cleaning unit tower, direct contact condensation section, condensate collection section, and related pipelines can be constructed using corrosion-resistant steel, rubber-lined steel, glass flake anti-corrosion structure, stainless steel, or engineering plastic lining structure. For parts in the direct contact condensation section and wet zone cleaning unit that are in long-term contact with circulating liquid, chloride ion corrosion-resistant materials are preferred to improve the long-term reliability of the system.

[0104] It should be noted that the embodiments of the present invention have better implementability and are not intended to limit the present invention in any way. Any person skilled in the art may use the above-disclosed technical content to change or modify it into equivalent effective embodiments. However, any modifications or equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A multi-stage synergistic purification and ultra-low emission treatment system for industrial flue gas, characterized in that, It includes a balanced conditioning unit, a primary dry reaction unit, an intermediate inertial separation unit, a secondary dry fine reaction filtration unit, a wet zone fine washing unit, a condensate extraction unit, and an exhaust unit, which are connected sequentially along the direction of industrial flue gas flow. It also includes an ash classification reflux unit, a condensate recycling unit, a clean flue gas reflux branch, and a by-product collection unit. The equalization conditioning unit is equipped with an industrial flue gas inlet, a clean flue gas return inlet, and a low-conductivity condensate atomization inlet; the primary dry reaction unit is equipped with a calcium-based absorbent dosing section. The intermediate inertial separation unit is located between the primary dry reaction unit and the secondary dry fine reaction filtration unit, and is provided with a gas outlet and a solid outlet; The two-stage dry fine reaction filtration unit is equipped with a sodium-based absorbent dosing section, a ceramic filtration module, and an ash collection section. The ash classification reflux unit is connected to the solid outlet and the ash collection section. The ash classification reflux unit includes a rotor classifier, a first metering feeder and a second metering feeder. The coarse particle outlet of the rotor classifier is connected to the first-stage dry reaction unit via the first metering feeder, and the fine particle outlet of the rotor classifier is connected to the second-stage dry fine reaction filtration unit via the second metering feeder. The wet-process zoned fine washing unit includes a lower oxidation absorption circulation zone and an upper neutral washing circulation zone connected sequentially from bottom to top. The lower oxidation absorption circulation zone is connected to a lower circulating liquid tank, and the upper neutral washing circulation zone is connected to an upper circulating liquid tank. A gas-liquid separation component is provided between the lower oxidation absorption circulation zone and the upper neutral washing circulation zone. The lower oxidation absorption circulation zone is provided with a lower spray layer, and the upper neutral washing circulation zone is provided with an upper spray layer. An oxidation air distribution component is provided within the lower oxidation absorption circulation zone. The condensate extraction unit includes an indirect cooling section, a direct contact condensation section, and a deep demisting section connected sequentially along the direction of industrial flue gas flow, as well as a condensate collection section located below the direct contact condensation section and the deep demisting section. The condensate separation and recycling unit is connected to the condensate collection section and is provided with a low conductivity condensate outlet and a high conductivity condensate outlet. The low conductivity condensate outlet is connected to the low conductivity condensate atomization inlet, and the high conductivity condensate outlet is connected to the lower circulating liquid tank via an independent replenishment pipe, and the liquid outlet of the independent replenishment pipe is located below the lower spray layer. The intake end of the clean flue gas return branch is connected to the downstream flue of the deep demisting section, and the outlet end of the clean flue gas return branch is connected to the clean flue gas return inlet. The lower circulating liquid tank is connected to the solid-liquid separation unit via a side-line solid-liquid separation branch. The clear liquid outlet of the solid-liquid separation unit is connected to the lower circulating liquid tank, and the solid phase outlet of the solid-liquid separation unit is connected to the by-product collection unit.

2. The industrial flue gas multi-stage synergistic purification and ultra-low emission treatment system according to claim 1, characterized in that, The equalization conditioning unit includes a mixing chamber, a static mixing section, and a ring-shaped dual-fluid atomizing nozzle group. The clean flue gas return inlet is tangentially connected to the mixing chamber, and the low-conductivity condensate atomizing inlet is connected to the dual-fluid atomizing nozzle group.

3. The industrial flue gas multi-stage synergistic purification and ultra-low emission treatment system according to claim 1, characterized in that, The primary dry reaction unit includes a Venturi acceleration section and a capacity expansion reaction section arranged sequentially along the direction of industrial flue gas flow, and the calcium-based absorbent dosing section is located upstream of the throat of the Venturi acceleration section.

4. The industrial flue gas multi-stage synergistic purification and ultra-low emission treatment system according to claim 3, characterized in that, The intermediate inertial separation unit is a swirling inertial separator, and the air inlet of the swirling inertial separator is tangentially connected to the expansion reaction section.

5. The industrial flue gas multi-stage synergistic purification and ultra-low emission treatment system according to claim 1, characterized in that, The secondary dry fine reaction filtration unit includes a mixing flue and multiple sets of ceramic filter modules arranged in parallel. The sodium-based absorbent dosing section is located on the mixing flue, and each set of ceramic filter modules has an independent ash hopper below it.

6. The industrial flue gas multi-stage synergistic purification and ultra-low emission treatment system according to claim 3, characterized in that, The ash grading reflux unit also includes a combined ash hopper, the first inlet of which is connected to the solid outlet, the second inlet of which is connected to the ash collection section, and the rotor classifier is located below the combined ash hopper.

7. The industrial flue gas multi-stage synergistic purification and ultra-low emission treatment system according to claim 6, characterized in that, The discharge end of the first metering feeder is connected to the inlet of the expansion reaction section.

8. The industrial flue gas multi-stage synergistic purification and ultra-low emission treatment system according to claim 6, characterized in that, The secondary dry fine reaction filtration unit also includes a mixing flue, the sodium-based absorbent dosing section is disposed on the mixing flue, the discharge end of the second metering feeder is connected to the mixing flue, and the connection position between the discharge end of the second metering feeder and the mixing flue is located downstream of the sodium-based absorbent dosing section and upstream of the ceramic filtration module.

9. The industrial flue gas multi-stage synergistic purification and ultra-low emission treatment system according to claim 1, characterized in that, The wet-process zoned fine washing unit includes a tower body and a gas-liquid separation component disposed between the lower oxidation absorption circulation zone and the upper neutral washing circulation zone. The gas-liquid separation component is a gas-liquid separation plate, which is provided with vent holes for industrial flue gas to pass upward and a liquid-sealed downcomer leg. The liquid inlet of the liquid-sealed downcomer leg is located on one side of the upper neutral washing circulation zone, and the liquid outlet of the liquid-sealed downcomer leg is located below the liquid level of the lower circulating liquid tank.

10. The industrial flue gas multi-stage synergistic purification and ultra-low emission treatment system according to claim 9, characterized in that, The upper circulating liquid tank is equipped with an overflow pipe, the outlet end of which is located below the liquid surface of the lower circulating liquid tank. The oxidation air distribution component is an oxidation air distributor located below the liquid surface of the lower circulating liquid tank.

Images