High-efficiency removal system and method for condensable particulate matter by low-temperature condensation coupled adsorption

Abstract

The application belongs to the field of pollutant control and specifically discloses a high-efficiency condensable particulate removal system and method based on low-temperature condensation coupled with adsorption. The system comprises a low-temperature condensation unit and a heat-carrying adsorption unit. The low-temperature condensation unit is used to build a supersaturated vapor environment to adsorb condensable particulates in flue gas to be treated to form liquid condensate. The heat-carrying adsorption unit comprises an adsorption chamber, an induced draft fan, a heat carrier and an adsorbent layer arranged in the adsorption chamber from bottom to top. The flue gas inlet of the adsorption chamber is arranged between the induced draft fan and the heat carrier to send the flue gas after condensation treatment into the adsorption chamber and make it flow upwards under the driving of the induced draft fan, and then the flue gas is sent to the adsorbent layer after being heated by the heat carrier to adsorb the condensable particulate precursors in the heated flue gas by the adsorbent. The application can realize the comprehensive removal of condensable particulates by low-temperature condensation coupled with adsorption, thereby further improving the emission control effect of condensable particulates.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of pollutant control, and more particularly, to a high-efficiency condensable particulate removal system and method based on low-temperature condensation coupled with adsorption. BACKGROUND

[0002] In recent years, China has made significant breakthroughs in the theory and technology of fixed-source pollutant removal. Conventional pollutants, such as filterable particulate matter, sulfur dioxide, and nitrogen oxides, have reached ultra-low emission standards of less than 10 mg / m 3 , 35 mg / m 3 , and 50 mg / m 3 , respectively. Condensable particulate matter, defined as liquid or solid particles (<2.5 μm) formed by cooling and condensation or reaction in the flue, is in the gaseous state in the flue and is emitted into the atmosphere. Due to its complex formation mechanism, condensable particulate matter contains a large amount of harmful substances, mainly inorganic components such as SO3 and organic components such as hydrocarbons, which seriously harm the natural environment and human health. Studies have shown that the actual emission concentration of condensable particulate matter from fixed sources is much higher than the emission standard for filterable particulate matter, and the proportion of condensable particulate matter emitted into the atmosphere is higher than that of filterable particulate matter.

[0003] Existing particulate matter control technologies can be divided into two categories: combined control and adsorption removal, both of which are developed for filterable particulate matter and can only achieve co-removal of condensable particulate matter. Combined control includes electrostatic precipitators, bag filters, and wet desulfurization devices, which mainly rely on methods such as loading electric charge, inertial filtration, and spraying slurry to remove large filterable particulate matter, but have limited efficiency for condensable particulate matter. Adsorption removal, such as activated carbon adsorption, has low efficiency for condensable particulate matter, with existing studies showing that the adsorption removal efficiency of activated carbon for condensable particulate matter is only 19-22% at 90°C. Due to the significant differences in chemical composition and physical form between condensable particulate matter and filterable particulate matter, existing particulate matter control technologies have low removal efficiency for condensable particulate matter, and there is an urgent need to develop emission control technologies specifically for condensable particulate matter.

[0004] In the prior art, CN115715921A discloses a high-efficiency device and method for removing condensable particulate matter from coal-fired power plants. This patent uses an absorbent solution spray to reduce the formation of SO3 at the SCR (Self-Containing Catalytic Reduction) stage, thereby removing condensable particulate matter. However, its removal device is located at the front end of the combined pollution control device and does not consider the generation and control of other components of condensable particulate matter during the combined removal process. CN113144867A discloses a system and method for efficient removal of fine particulate matter in conjunction with flue gas desulfurization. This system uses the recycling of spray slurry to form particulate agglomerates, thereby removing fine particulate matter from coal-fired power plants. However, the removal strategy of this patent does not consider the pollution problems that may be caused by the desulfurization slurry being emitted into the atmosphere with the flue gas. CN111632764A discloses a high-efficiency cooling coupled pre-charged SO3 enhanced agglomeration device and method. This patent uses cooling and charging to remove SO3, thereby reducing blue plume emissions from coal-fired power plants. However, the removal target in this patent document is only for some gaseous precursors of condensable particulate matter. The removal efficiency for other condensable particulate matter precursors is low, and the actual emission capacity of the flue gas after cooling is not taken into account. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this application provides a system and method for the efficient removal of condensable particulate matter using low-temperature condensation coupled adsorption, aiming to solve the problem that existing particulate matter control devices can only achieve synergistic removal of condensable particulate matter, and the removal efficiency is not high.

[0006] According to one aspect of this application, a high-efficiency removal system for condensable particulate matter using low-temperature condensation coupled adsorption is provided, specifically comprising a low-temperature condensation unit and a heat-carrying adsorption unit, wherein:

[0007] The low-temperature condensation unit is used to create a supersaturated steam environment, so that water vapor condenses with ultrafine particles as nuclei to form embryonic droplets, which adsorb condensable particles in the flue gas to be treated to form liquid condensate, and the condensed flue gas is sent to the heat-carrying adsorption unit.

[0008] The heat-carrying adsorption unit includes an adsorption chamber and, from bottom to top, an induced draft fan, a heat carrier, and an adsorbent layer arranged inside the adsorption chamber. The flue gas inlet of the adsorption chamber is located between the induced draft fan and the heat carrier, and is used to send the condensed flue gas into the adsorption chamber. Driven by the induced draft fan, the flue gas flows upward and is heated by the heat carrier before being sent to the adsorbent layer. The adsorbent is used to adsorb the condensable particulate precursors in the heated flue gas, and the adsorbed flue gas is finally discharged directly.

[0009] Compared with the prior art, the technical solutions conceived in this application, by setting up a low-temperature condensation unit and a heat-carrying adsorption unit, can efficiently remove various condensable particulate matter, including inorganic and organic components, and the treated flue gas can be directly emitted.

[0010] As a further preferred embodiment, the low-temperature condensation unit includes a condensation chamber, at least one water mist generator, and at least one heat exchanger. The condensation chamber has a flue gas inlet at its left end and a flue gas outlet at its right end, which is connected to the adsorption chamber via a flue gas pipe. Each of the water mist generators is spaced apart at the top of the condensation chamber along the flue gas flow direction and connected to the heat exchanger, for providing condensate or steam to the condensation chamber to create a supersaturated steam environment.

[0011] As a further preferred embodiment, the efficient removal system for condensable particulate matter also includes a liquid storage unit, which includes at least one liquid storage tank. Each of the liquid storage tanks is spaced apart along the flue gas flow direction and is connected to a low-temperature condensation unit for collecting liquid condensate from the low-temperature condensation unit.

[0012] As a further preferred embodiment, the low-temperature condensation unit further includes at least one liquid collection plate, each of which is spaced apart inside the condensation chamber along the flue gas flow direction, and the liquid collection plate is located below the flue gas inlet for collecting liquid condensate.

[0013] As a further preferred embodiment, the spray angle of the water mist generator is 45° to 135°.

[0014] As a further preferred embodiment, the surface of the liquid accumulation plate has openings with an opening rate of 25% to 45%, an inclination angle of 30° to 60°, and a hole diameter of 10mm to 30mm.

[0015] As a further preferred embodiment, the diameter of the condensation chamber gradually decreases from top to bottom, while the diameter of the adsorption chamber gradually increases from top to bottom.

[0016] As a further preferred embodiment, the adsorbent is a sodium-based adsorbent, a calcium-based adsorbent, a magnesium-based adsorbent, or activated carbon.

[0017] As a further preferred embodiment, the heat-carrying adsorption unit further includes an airflow regulating component, which is connected to an induced draft fan and is used to adjust the airflow of the induced draft fan according to the temperature and flow rate of the adsorption chamber.

[0018] According to another aspect of this application, a method for efficient removal of condensable particulate matter using low-temperature condensation coupled adsorption is provided. This method employs the aforementioned efficient condensable particulate matter removal system, specifically: flue gas is fed into a low-temperature condensation unit, where water vapor is condensed with ultrafine particles as nuclei to form embryonic droplets, thereby adsorbing the condensable particulate matter in the flue gas to be treated. The condensed flue gas is then fed into a heat-carrying adsorption unit for heating, and discharged after adsorption by an adsorbent.

[0019] In summary, compared with the prior art, the technical solutions conceived in this application have the following main technical advantages:

[0020] 1. This application provides a system specifically designed for the removal of condensable particulate matter. By setting up a low-temperature condensation unit and a heat-carrying adsorption unit, the system can achieve comprehensive removal of condensable particulate matter through low-temperature condensation coupled adsorption. The removal targets include not only the important components of condensable particulate matter, SO3 and various inorganic salts, but also organic components such as hydrocarbons, lipids, and desulfurization slurry remaining during actual flue gas discharge. This further improves the emission control effect of condensable particulate matter. Furthermore, by using a heat carrier to raise the temperature of the condensed flue gas, it can be directly discharged into the atmosphere.

[0021] 2. At the same time, by setting up a liquid storage unit, this application can collect the liquid condensate in the low-temperature condensation unit to achieve water resource reuse and thus achieve water conservation.

[0022] 3. Furthermore, by optimizing the parameters of each component in the low-temperature condensation unit, this application can further improve the removal effect of condensable particulate matter. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of the low-temperature condensation coupled adsorption high-efficiency removal system for condensable particulate matter provided in the embodiments of this application.

[0024] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0025] 1-Heat exchanger, 2-Water mist generator, 3-Condensation chamber, 4-Liquid collection plate, 5-Induction valve, 6-Liquid storage tank, 7-Flue gas duct, 8-Exhaust fan, 9-Heat carrier, 10-Adsorbent conveyor belt, 11-Air volume regulating component, 12-Adsorption chamber. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0027] likeFigure 1 As shown, this application provides a high-efficiency removal system for condensable particulate matter using low-temperature condensation coupled adsorption, specifically including a low-temperature condensation unit and a heat-carrying adsorption unit, wherein:

[0028] The low-temperature condensation unit is used to create a supersaturated steam environment, so that water vapor condenses with ultrafine particles as nuclei to form embryonic droplets, thereby adsorbing condensable particulate matter in the flue gas to be treated to form liquid condensate, and then sending the condensed flue gas into the heat transfer adsorption unit.

[0029] The heat transfer adsorption unit includes an adsorption chamber 12 and, from bottom to top, an induced draft fan 8, a heat transfer medium 9, and an adsorbent layer 10 arranged inside the adsorption chamber 12. The flue gas inlet of the adsorption chamber 12 is located between the induced draft fan 8 and the heat transfer medium 9, so that the condensed flue gas is sent into the adsorption chamber 12 and flows upward under the drive of the induced draft fan 8. After being heated by the heat transfer medium 9, it is sent to the adsorbent layer 10, where the adsorbent adsorbs the condensable particulate precursors in the heated flue gas. Finally, the adsorbed flue gas is directly discharged into the atmosphere. The heat transfer adsorption unit heats up the condensed flue gas, removing residual pollutants while increasing the flue gas temperature, giving it the ability to rise independently and be discharged smoothly into the atmosphere.

[0030] Specifically, the induced draft fan 8 is used to provide dry air to mix the condensed flue gas with the dry air and provide upward power for it. The specific number of induced draft fans 8 can be determined according to the actual flue gas volume. When multiple induced draft fans are set according to actual needs, the connection method between the multiple induced draft fans can be set to parallel. The heat carrier 9 is used to provide heat energy to heat up the condensed flue gas and heat the adsorbent to activate it and improve the adsorption capacity of the adsorbent. The adsorbent layer 10 can be equipped with a conveyor belt to transport the adsorbent to ensure that the adsorbent is always in motion, so that the flue gas and the adsorbent can come into contact and react with each other, thereby increasing the contact area between the adsorbent and the flue gas and fully adsorbing the organic components and possible residual slurry in the residual condensable particulate matter in the flue gas.

[0031] This application addresses the problem that existing particulate matter control devices can only achieve synergistic removal of condensable particulate matter with poor treatment effects. It proposes a highly efficient removal system specifically for condensable particulate matter, filling a current technological gap. This system utilizes a low-temperature condensation unit and a heat-carrying adsorption unit to remove not only the essential components of condensable particulate matter, SO3 and various inorganic salts, but also organic components such as hydrocarbons, lipids, and residual desulfurization slurry from actual flue gas emissions. The supersaturated steam environment created by the low-temperature condensation unit allows water vapor to condense around ultrafine particles, forming embryonic droplets. These droplets effectively adsorb SO3 and various inorganic salts from the aforementioned components. The heat-carrying adsorption unit activates the adsorbent by heating, thereby removing the organic components of condensable particulate matter, such as hydrocarbons and lipids, and residual desulfurization slurry from actual flue gas emissions, ultimately achieving highly efficient removal of condensable particulate matter. In practical applications, the low-temperature condensation coupled adsorption high-efficiency removal system for condensable particulate matter provided in this application can be set at the end of the power plant flue gas treatment system to efficiently remove condensable particulate matter separately before flue gas emission, effectively solving the current problem of high emissions of condensable particulate matter.

[0032] Furthermore, the low-temperature condensation unit includes a condensation chamber 3, at least one water mist generator 2, and at least one heat exchanger 1. The condensation chamber 3 provides space for mixing and condensing flue gas and condensing steam. The condensation chamber 3 has a flue gas inlet at its left end and a flue gas outlet at its right end, connected to the adsorption chamber 12 via a flue gas pipe 7. This allows the flue gas to flow from left to right within the condensation chamber 3, effectively increasing the residence time of the flue gas within the condensation chamber 3 and ensuring that condensable particulate matter in the flue gas can fully contact the adsorption droplets, thereby improving condensability. The particulate matter removal rate is achieved by arranging water mist generators 2 at intervals along the flue gas flow direction at the top of the condensing chamber 3 and connecting them to the heat exchanger 1. These generators supply condensate or steam to the condensing chamber 12 to create a supersaturated steam environment, stabilizing the saturated steam value of the condensing chamber 12 at 1.1–1.2. The heat exchanger 1 precisely regulates the temperature of the liquid sprayed from the water mist generators 2, with the condensate temperature preferably between 30°C and 50°C, thus achieving the synergistic removal of multiple pollutants. The spray angle of the water mist generators 2 is between 45° and 135°. Each water mist generator 2 is equipped with an electronic flow control valve with adjustable spray volume. The steam flow rate of the water mist generators 2 can be determined based on the actual flue gas volume. The specific number of water mist generators 2 can be determined based on the actual flue gas volume. The water mist generators 2 are located at the top of the condensing chamber 3, and their nozzles can spray downwards, along the flue gas flow, or at other spray angles in between. The nozzles can be pressure atomizing nozzles or dual-fluid atomizing nozzles.

[0033] Preferably, the condenser chamber 3 is equipped with multiple sets of parallel temperature and humidity detectors, and the temperature and humidity detectors are connected to the water mist generator 2 and the heat exchanger 1 through a control module to adjust the saturated steam value of the condenser chamber 12 and the temperature of the liquid sprayed by the water mist generator 2 in real time.

[0034] Furthermore, the efficient particulate matter removal system also includes a liquid storage unit, which comprises at least one liquid storage tank 6. These tanks 6 are spaced apart along the flue gas flow direction and connected to the condensation chamber 3 to collect liquid condensate within the chamber. This liquid condensate can be returned to the water mist generator 2 for secondary use, achieving water resource reuse. The specific number of liquid storage tanks 6 and sensing valves 5 can be determined based on the actual amount of liquid condensate generated. When multiple liquid storage tanks 6 are provided in the liquid storage unit according to actual needs, the connection between these tanks 6 can be configured as a parallel connection. In this parallel connection, the opening and closing of different liquid storage tanks 6 can be determined according to actual needs. During maintenance due to a fault, only the corresponding liquid storage tank 6 needs to be closed, without affecting the operation of the entire system, resulting in a high fault tolerance rate.

[0035] Preferably, a sensing valve 5 is provided between the liquid storage tank 6 and the condensation chamber 3. The sensing valve 5 is used to quantitatively deliver liquid condensate to the liquid storage tank 6. During operation, the sensing valve 5 is normally closed. When the liquid condensate in the condensation chamber 3 accumulates to a certain weight, the sensing valve 5 opens and delivers the liquid condensate to the liquid storage tank 6. The weight sensing value of the sensing valve 5 is 1 / 4 to 1 / 5 of the storage capacity of the liquid storage tank.

[0036] Furthermore, the low-temperature condensation unit also includes at least one liquid collection plate 4. These liquid collection plates 4 are spaced apart inside the condensation chamber 3 along the flue gas flow direction and are positioned below the flue gas inlet to collect liquid condensate. The surface of the liquid collection plate 4 is perforated, with an opening ratio of 25%–45%, an inclination angle of 30°–60°, and a hole diameter of 10mm–30mm. The liquid collection plate 4 enables more uniform flue gas distribution, directs the airflow towards the central area of ​​the condensation chamber 3, reduces the scouring of the walls by the spray, and improves flow deviation. The spray travels from top to bottom, forming a liquid film of a certain height on the liquid collection plate 4. The flue gas passes through the liquid-holding layer on the liquid collection plate 4 from top to bottom, increasing the gas-liquid contact time. The parameters of opening ratio, hole diameter, and inclination angle affect the formation of the liquid layer. By optimizing these three parameters, the stability and appropriate height of the liquid-holding layer on the liquid collection plate 4 can be ensured.

[0037] Furthermore, the diameter of the condensation chamber 3 gradually decreases from top to bottom, making it easier for the liquid condensate to gather at the bottom by inertia or gravity, thus facilitating the collection of the liquid condensate; the diameter of the adsorption chamber 12 gradually increases from top to bottom, thereby better conforming to the shape of the chimney flue, and the adsorption chamber 12 can be set in the chimney during operation.

[0038] Furthermore, the heat carrier 9 includes one or more parallel-placed constant-temperature heating elements, and the temperature of the heat carrier 9 is maintained at 130°C to 150°C.

[0039] Furthermore, the adsorbent is a sodium-based adsorbent, a calcium-based adsorbent, a magnesium-based adsorbent, or activated carbon, which enables the adsorption of various condensable particulate precursors, including inorganic and organic components. The adsorbent layer 10 is made of a corrosion-resistant material to improve its stability.

[0040] Furthermore, the heat-carrying adsorption unit also includes an airflow regulating component. The airflow regulating component 11 is located at the outlet of the adsorption chamber 12 and connected to the induced draft fan 8. It is used to regulate the power of the induced draft fan 8 to adjust the airflow according to the temperature and flow rate of the adsorption chamber 12.

[0041] According to another aspect of this application, a method for efficient removal of condensable particulate matter using low-temperature condensation coupled adsorption is provided. This method employs the aforementioned efficient condensable particulate matter removal system, specifically: flue gas is fed into a low-temperature condensation unit, where water vapor is condensed with ultrafine particles as nuclei to form embryonic droplets, thereby adsorbing the condensable particulate matter in the flue gas to be treated. The condensed flue gas is then fed into a heat-carrying adsorption unit for heating, and discharged after adsorption by an adsorbent.

[0042] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A system for efficient removal of condensable particulate matter by low temperature condensation coupled with adsorption, characterized in that, The system comprises a low-temperature condensing unit and a heat-carrying adsorption unit, wherein: The low-temperature condensing unit is used to provide condensed water or steam to build a supersaturated steam environment, so that water vapor condenses on ultrafine particulate matter to form embryo droplets, and SO3 and inorganic salts in condensable particulate matter in the flue gas to be treated are adsorbed to form liquid condensate, and the flue gas after condensation treatment is sent to the heat-carrying adsorption unit. The heat-carrying adsorption unit comprises an adsorption chamber (12) and, from bottom to top, an induced draft fan (8), a heat carrier (9) and an adsorbent layer (10) arranged in the adsorption chamber (12) in sequence, and the flue gas inlet of the adsorption chamber (12) is opened between the induced draft fan (8) and the heat carrier (9) to send the flue gas after condensation treatment into the adsorption chamber (12) and make it flow upward under the driving of the induced draft fan (8), and after being heated by the heat carrier (9), the flue gas is sent to the adsorbent layer (10) to adsorb hydrocarbons, lipids and desulfurization slurry remaining during actual flue gas emission in the condensable particulate matter in the heated flue gas by using the adsorbent, and finally the flue gas after adsorption treatment is directly discharged.

2. The system for high-efficiency removal of condensable particulate matter of claim 1, wherein, The low-temperature condensing unit comprises a condensing chamber (3), at least one water mist generator (2) and at least one heat exchanger (1), the left end of the condensing chamber (3) is provided with a flue gas inlet, the right end is provided with a flue gas outlet and is connected with the adsorption chamber (12) through a flue gas pipeline (7); each water mist generator (2) is arranged at the top of the condensing chamber (3) in the direction of flue gas flow and is connected with the heat exchanger (1) to provide condensed water or steam to the condensing chamber (12) to build a supersaturated steam environment.

3. The system of claim 1, wherein the system is configured to remove at least 90% of the condensable particulate matter. The system further comprises a liquid storage unit, the liquid storage unit comprises at least one liquid storage tank (6), each liquid storage tank (6) is arranged in the direction of flue gas flow and is connected with the low-temperature condensing unit to collect the liquid condensate of the low-temperature condensing unit. ​ 4. The system of claim 1, wherein the system is configured to remove at least 90% of the condensable particulate matter. The low-temperature condensing unit further comprises at least one liquid accumulation plate (4), each liquid accumulation plate (4) is arranged in the condensing chamber (3) in the direction of flue gas flow, and the liquid accumulation plate (4) is arranged below the flue gas inlet to accumulate the liquid condensate.

5. The system for high-efficiency removal of condensable particulate matter of claim 2, wherein, The spray angle of the water mist generator (2) is 45°-135°.

6. The high-efficiency particulate condensing system of claim 4, wherein, The surface of the liquid accumulation plate (4) is provided with holes, the hole rate is 25%-45%, the inclination angle of the holes is 30°-60°, and the hole diameter is 10mm-30mm.

7. The system of claim 2, wherein the system further comprises a filter. The diameter of the condensing chamber (3) gradually decreases from top to bottom, and the diameter of the adsorption chamber (12) gradually increases from top to bottom.

8. The system of claim 1, wherein the system is configured to remove at least 90% of the condensable particulate matter. The adsorbent is sodium-based adsorbent, calcium-based adsorbent, magnesium-based adsorbent or activated carbon.

9. The system for high efficiency removal of coagulatable particulate matter according to any one of claims 1 to 8, wherein, The heat-carrying adsorption unit further comprises a wind volume adjusting assembly, the wind volume adjusting assembly (11) is connected with the induced draft fan (8) to adjust the air supply volume of the induced draft fan (8) according to the temperature and flow of the adsorption chamber (12).

10. A method for high-efficiency removal of condensable particulate matter by low-temperature condensation coupled with adsorption, characterized in that, The method for high-efficiency removal of condensable particulate matter adopts the system for high-efficiency removal of condensable particulate matter as claimed in any one of claims 1 to 9, and specifically, the flue gas is sent into a low-temperature condensation unit, and water vapor is used to condense the ultrafine particulate matter as a core to form embryo droplets, so as to adsorb SO3 and inorganic salts in the condensable particulate matter in the flue gas to be treated, and the flue gas after condensation treatment is sent into a heat-carrying adsorption unit for heating, and the hydrocarbons, lipids and desulfurization slurry remaining during actual flue gas emission in the condensable particulate matter in the heated flue gas are adsorbed by the adsorbent and then discharged.

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