Waste gas purification treatment system and method based on hydrodynamic cavitation technology

Abstract

The invention discloses a waste gas purification treatment system and method based on a hydrodynamic cavitation technology, the waste gas purification treatment system comprises a pretreatment unit, a cavitation reaction unit and a post-treatment unit, all the units are connected through pipelines, valves and a control system to form a closed-loop treatment flow; the specific structure is as follows: the pretreatment unit comprises a Venturi mixer and a multi-medium filter; the venturi mixer is provided with a contraction section, a throat part and a diffusion section, the throat part of the venturi mixer is communicated with a water outlet of the multi-medium filter through a pipeline, multiple layers of filter materials are arranged in the multi-medium filter, and the filter materials are composite filter materials such as quartz sand and activated carbon; the odor collecting pipeline is connected with an air inlet of the venturi mixer, so that turbulent mixing of odor and purified water is realized. The invention relates to the technical field of waste gas purification treatment, and particularly provides a waste gas purification treatment system and method based on a hydrodynamic cavitation technology.

Description

Technical Field

[0001] This invention relates to the field of waste gas purification and treatment technology, specifically to a waste gas purification and treatment system and method based on hydraulic cavitation technology. Background Technology

[0002] Waste gas purification refers to the process of removing harmful components from waste gas through physical, chemical, or biological methods. Currently, the mainstream technologies in the field of waste gas deodorization are divided into four categories, and their application scenarios, core structures, and principles are as follows: 1. Physical adsorption type (activated carbon / molecular sieve): The core structure is an adsorption bed, which uses the specific surface area of ​​porous materials to adsorb odor molecules. It is suitable for the treatment of low-concentration, single-component waste gas and is commonly used in small sewage treatment plants for deodorization.

[0003] 2. Chemical oxidants (ozone / It consists of an oxidant generator, such as an ozone generator, and a mixing reactor. It decomposes pollutants by adding strong oxidants and is widely used in the treatment of medium and high concentration industrial waste gas.

[0004] 3. Biological treatment type (MBBR / biofilter): Includes biological carrier filling layer and air and water distribution system. It uses functional microbial community to metabolize and degrade pollutants and is suitable for low-concentration waste gas scenarios such as municipal sewage treatment plants.

[0005] 4. Emerging technologies (photocatalysis / plasma / membrane separation): Photocatalysis technology consists of an ultraviolet light source and a catalyst carrier, which uses photogenerated carriers to oxidize pollutants; plasma technology generates plasma through high-voltage discharge to degrade pollutants; membrane separation technology relies on the sieving effect of special membranes to retain pollutants. All three are mostly used for the treatment of waste gases with special components.

[0006] While these techniques have some effect, they also have significant drawbacks: Physical adsorption technologies rely on porous materials such as activated carbon to adsorb pollutants, but they saturate quickly, require frequent replacement of consumables, and have high maintenance costs; they are also ineffective for complex mixtures of odor molecules, such as... Low adsorption efficiency Removal rate <60%; regeneration is difficult, and high-temperature steam regeneration can easily lead to material structure damage, with active site loss rate exceeding 30%.

[0007] Chemical oxidation technologies: These technologies degrade pollutants using oxidants such as ozone, but they have high risks of producing byproducts, such as secondary pollutants like aldehydes and ketones; they also have high energy consumption; strict safety controls are required, with the operating concentration needing to be precisely controlled below 0.1 ppm; and there is a high risk of leakage.

[0008] Biological treatment technologies: These utilize microorganisms to degrade pollutants, but they are highly sensitive to environmental fluctuations, especially temperature fluctuations. Efficiency drops sharply by 40%-60%; startup cycle is long, requiring 2-4 months to build up the microbial community; it is weak in resistance to shocks, and instantaneous high concentrations of odor can easily lead to system collapse.

[0009] Emerging technologies: Photocatalysis technology uses ultraviolet light sources with short lifespans (less than 8000 hours) and quantum yields of less than 15%; plasma technology boasts high energy density. Ozone generation exceeds the standard by 3-5 times; membrane pores of membrane separation technology are easily blocked by polar substances such as hydrogen sulfide, and the flux decrease rate exceeds 20% / month.

[0010] Industry data corroborates these shortcomings: for example, statistics from a municipal wastewater treatment plant show that the annual replacement cost of activated carbon accounts for 38% of the total treatment cost, the failure rate of the chemical spraying system is as high as 62%, and the biological filter operates poorly during winter. The removal rate dropped from 92% in summer to 57%. Therefore, there is an urgent need to develop a high-efficiency, low-consumption, and pollution-free waste gas purification technology. Summary of the Invention

[0011] The technical problem to be solved by this invention is that existing waste gas purification technologies suffer from problems such as rapid adsorption saturation, poor selectivity, by-product risks, high energy consumption, environmental sensitivity, weak impact resistance, and clogging.

[0012] This invention provides the following technical invention: A waste gas purification and treatment system based on hydraulic cavitation technology is proposed, comprising a pretreatment unit, a cavitation reaction unit, and a post-treatment unit. Each unit is connected via pipelines, valves, and a control system to form a closed-loop treatment process; the specific structure is as follows: Pretreatment unit: includes a Venturi mixer and a multi-media filter; the Venturi mixer is equipped with a contraction section, a throat and a diffusion section, and its throat is connected to the outlet of the multi-media filter through a pipe. The multi-media filter has multiple layers of filter media, which are composite filter media such as quartz sand and activated carbon; the odor collection pipe is connected to the air inlet of the Venturi mixer to realize turbulent mixing of odor and purified water. The cavitation reaction unit includes a high-pressure centrifugal pump and a multi-stage cavitation reactor. The high-pressure centrifugal pump uses a multi-stage impeller structure to increase the liquid pressure to a set pressure. The multi-stage cavitation reactor consists of a titanium alloy cavity, a conical diffuser section, and a nozzle array. It generates cavitation bubbles by progressively scaling the cavity, and releases energy to generate free radicals when the cavitation collapses. The outlet of the high-pressure centrifugal pump is connected to a 316L stainless steel pressure-resistant pipe (withstanding 15...). (Pressure) is connected to the first-stage chamber of the multi-stage cavitation reactor; Post-treatment unit: includes a nano-ceramic membrane separator and a neutralization tank; the inlet of the nano-ceramic membrane separator is connected to the end outlet of the multi-stage cavitation reactor via a pipe equipped with a flow meter and pressure sensor. The nano-ceramic membrane separator employs... Ultra-fine pore hollow fiber membrane modules are used to retain small molecule organic matter; the neutralization tank is equipped with a stirring device and The online monitoring instrument adjusts the effluent by adding alkaline agents such as sodium carbonate. To neutralize; the end of the cavitation reactor is connected to the membrane separator through a feed pipe. The permeate from the membrane separator enters the neutralization tank, while the neutralization tank is connected to the membrane separator through a pulse backwashing pipeline to achieve periodic backwashing.

[0013] Preferred technical solution: The system also includes an intelligent control system, comprising a sensor network, actuators, and safety interlock devices; the sensor network is used for monitoring. , , concentration, The actuator controls the high-pressure pump speed and the dosing pump dosage by controlling the frequency converter; the safety interlock device is used to automatically cut off the pump power and start the pressure relief valve when the pressure exceeds the limit.

[0014] This invention discloses a waste gas purification and treatment method based on hydraulic cavitation technology, the specific process including the following steps: (1) Pretreatment stage: After collection, the waste gas enters the Venturi mixer. The high-speed airflow generates negative pressure at the throat and draws in the circulating water purified by the multi-media filter, forming a gas-liquid turbulent mixed flow. At the same time, the multi-media filter intercepts particles with a diameter >10 in the waste gas. Particulate matter and oil; (2) Cavitation reaction stage: The gas-liquid mixture enters the high-pressure centrifugal pump, and is pressurized step by step by the multi-stage impeller. The high-pressure gas-liquid mixture enters the multi-stage cavitation reactor, where a large number of cavitation bubbles are formed in the progressively expanding and contracting chambers. When the cavitation bubbles collapse, they release instantaneous energy and generate high concentrations of cavitation gas. Free radicals, oxidative decomposition , , Pollutants, etc., to achieve pollutant mineralization, producing Free radicals, with a generation rate of up to ; (3) Post-treatment stage: The reaction mixture enters the nano-ceramic membrane separator, where the membrane module retains incompletely decomposed small molecule organic matter and metal ions, and the permeate enters the neutralization tank for adjustment. After reaching emission standards or being reused, the dosing pump will adjust according to... Sensor feedback allows for the automatic addition of neutralizing agents such as sodium carbonate to regulate the process. The temperature reaches 6.5-7.5. After meeting the standard, part of the solution is recycled to the pretreatment unit, and the rest is discharged through the drain pipe. The nano-ceramic membrane separator is pulsed backwashed every 8 hours through the circulating water in the neutralization tank to restore the membrane flux. The backwashing system automatically cleans the membrane module every 8 hours.

[0015] Furthermore, it also includes safety interlock control. When the system pressure exceeds the set value, the PLC controller automatically cuts off the power supply to the high-pressure pump and activates the pressure relief valve to ensure the safe operation of the system.

[0016] The present invention proposes a waste gas purification system and method based on hydraulic cavitation technology. The beneficial effects achieved by adopting the above scheme are as follows: (1) High efficiency, safety and environmental protection: Highly active free radicals are generated through hydraulic cavitation, and pollutants can be mineralized in a single pass. , and The overall removal rate is >95%, and there is no adsorption saturation problem. For example, after application in a landfill... The removal rate is consistently >99%, and the operating cost is only 1 / 3 of that of an activated carbon system; there is no secondary pollution, and the TOC in the effluent is <10. (lower than EPA) (Limits), and no hazardous chemicals are required, so the risk of leakage is close to zero; (2) High adaptability: Modular design supports rapid expansion through "sensors" The actuator uses closed-loop control to achieve adaptive adjustment of odor load. Precise control and safety interlocks reduce manual operation intensity, and the failure rate is reduced by more than 80% compared to traditional chemical spraying systems; the reaction is unaffected by temperature. Influence( to Efficiency fluctuation <5%, strong shock resistance (tolerant) Peak concentration 5000ppm). Simultaneously, cavitation breaks down large organic molecules, reducing their particle size from 500nm to 50nm, alleviating membrane fouling, decreasing membrane flux decay from 20% / month to 3% / month, and extending membrane module lifespan. (3) Energy-saving and economical: The energy intensity is only 1 / 8 of that of plasma technology. Furthermore, there is no need for consumable replacements, reducing maintenance costs. Attached Figure Description

[0017] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a process flow diagram of a waste gas purification system and method based on hydraulic cavitation technology proposed in this invention. Detailed Implementation

[0018] The technologies described below will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0019] Example 1: A waste gas purification and treatment system based on hydraulic cavitation technology, applied to the treatment of high-concentration odor in a sewage treatment plant; This embodiment aims to solve the problem of extremely high concentrations of odor generated by the anaerobic fermentation of sludge in wastewater treatment plants. Existing biological filters and activated carbon adsorption systems are costly to operate, pose a risk of secondary pollution, and struggle to consistently meet new environmental protection requirements. This embodiment employs hydraulic cavitation technology to achieve efficient, low-cost odor purification without secondary pollution.

[0020] The system includes: Pretreatment unit: Set one unit with an air volume of 3000 A negative pressure suction hood, covering the surface of the secondary sedimentation tank, is used to collect odorous gases. The suction pipe is connected to the inlet of a Venturi mixer. The throat of the Venturi mixer is connected via a pipe to the outlet of a multi-media filter, which is filled from top to bottom with a composite filter media of activated carbon (1-2 mm particle size) and quartz sand (0.5-1.0 mm particle size). Its influent comes from the plant's reclaimed water network. The gas-liquid ratio is dynamically stabilized by adjusting valves. .

[0021] Cavitation reaction unit: Employs three parallel multi-stage cavitation reactors to handle the processing scale (single unit processing capacity 1500). The outlet of the Venturi mixer is connected via a pipe to the inlet of a high-pressure centrifugal pump, which employs a multi-stage impeller structure. The pump outlet is connected to the main pipe of the parallel cavitation reactor group via a 316L stainless steel pressure-resistant pipe. Each cavitation reactor body is a 5-stage scaling chamber made of TA2 titanium alloy, with an internal nozzle array.

[0022] Post-treatment unit: The effluent from the cavitation reactor enters a nano-ceramic membrane separator through a pipe equipped with a flow meter and pressure sensor. This membrane separator uses a pore size of... Hollow fiber ceramic membrane module. The permeate pipe of the membrane separator is connected to a volume of The neutralization tank is equipped with a mechanical stirrer and an online pH monitor, and is connected to a sodium carbonate dosing pump. The neutralization tank is connected to the inlet side of the nano-ceramic membrane separator via a pulse backwash line with a pump and solenoid valve.

[0023] Intelligent control system: set at key points of the system , Concentration and pressure sensors are included. The PLC controller receives sensor signals and uses a frequency converter to adjust the speed of the high-pressure centrifugal pump in real time (control range 500-2500 rpm), and controls the start and stop of the dosing pump. Safety interlock program setting: When the system pressure exceeds... At that moment, the PLC immediately cuts off the power supply to the high-pressure pump and opens the pipeline pressure relief valve.

[0024] A process for purifying waste gas based on hydraulic cavitation technology includes the following steps: Odor (peak concentration) 8000 ppm 150 The water is collected under negative pressure and enters the Venturi mixer, where it is violently mixed with regenerated water from the multi-media filter at the throat, forming gas-liquid turbulence and simultaneously removing large particles.

[0025] The gas-liquid mixture is pressurized to 12 by a high-pressure centrifugal pump. Subsequently, the cavitation bubbles were evenly distributed to three titanium alloy cavitation reactors. A large number of cavitation bubbles were generated within the progressively expanding and contracting chambers, and their collapse produced a high concentration of cavitation bubbles. Free radicals (measured generation rate reaches) ),Will , When pollutants are oxidized and decomposed into , Harmless substances.

[0026] The reacted mixture enters a nano-ceramic membrane separator, which retains incompletely mineralized small-molecule intermediates and any trace metal ions that may be present. The permeate enters a neutralization tank. The online monitoring instrument controls the dosing pump to add sodium carbonate, which will then be added to the effluent. Precisely adjust to The regulated clean water is partially reused in the Venturi mixer, with the remainder discharged after meeting standards. The nano-ceramic membrane separator automatically initiates a pulse backwash every 8 hours of operation. The backwash water comes from the compliant effluent of the neutralization tank, with a backwash pressure of 0.5. The duration is 120 seconds.

[0027] Implementation results: According to continuous monitoring by the environmental protection department, the odor concentration at the factory boundary was... Stable <8 ppm <0.08 It is superior to the Class A standard of the "Discharge Standard of Pollutants for Municipal Wastewater Treatment Plants" (GB 18918-2002). The annual operating cost of the system is reduced by approximately RMB 450,000 compared to the original system, and no secondary pollutants such as waste activated carbon are generated. The static investment payback period is approximately 18 months.

[0028] Cost comparison It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, material, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, material, or apparatus.

[0029] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A waste gas purification treatment system based on a hydrodynamic cavitation technique, characterized by, The closed loop treatment process is formed by connecting the pretreatment unit, cavitation reaction unit and post-treatment unit through pipelines, valves and a control system, and the specific structure is as follows: The pretreatment unit comprises a Venturi mixer and a multi-medium filter; the Venturi mixer is provided with a contraction section, a throat and a diffusion section, the throat is communicated with a water outlet of the multi-medium filter through a pipeline, the multi-medium filter is internally provided with multi-layer filter materials, the filter materials are composite filter materials such as quartz sand and activated carbon, a foul gas collecting pipeline is connected with an air inlet of the Venturi mixer to realize turbulent mixing of the foul gas and purified water; The cavitation reaction unit comprises a high-pressure centrifugal pump and a multi-stage cavitation reactor; the multi-stage cavitation reactor is composed of a titanium alloy cavity, a conical diffuser section and a nozzle array, cavitation bubbles are generated by gradually scaling the cavity, and free radicals are generated by releasing energy when the cavitation collapses; the outlet of the high-pressure centrifugal pump is communicated with a first-stage cavity of the multi-stage cavitation reactor through a pipeline; Post-treatment unit: including nanoceramic membrane separator and neutralization tank; nanoceramic membrane separator adopts Ultrafine pore size hollow fiber membrane module; The neutralization tank is equipped with stirring device and Online monitoring instrument; the end of the cavitation reactor is connected with the membrane separator through the feeding pipe, the permeate of the membrane separator enters the neutralization tank, and the neutralization tank is connected with the membrane separator through the pulse backwashing pipeline to realize regular backwashing.

2. A flue gas cleaning system based on hydrodynamic cavitation technology as claimed in claim 1 wherein, The system further comprises an intelligent control system, including a sensor network, an actuator and a safety interlock device; the sensor network is used for monitoring , , concentration, and pressure; the actuator adjusts the rotating speed of the high-pressure pump and the dosing of the dosing pump by controlling the frequency converter; the safety interlock device is used for automatically cutting off the power supply of the pump and starting the pressure relief valve when the pressure exceeds the limit.

3. A method for exhaust gas purification treatment based on the hydrodynamic cavitation technology according to any one of claims 1-2, characterized in that, The specific process comprises the following steps: The specific process comprises the following steps: (1) Pretreatment stage: the exhaust gas is collected and enters the Venturi mixer. The high-speed airflow generates negative pressure at the throat, which sucks in the circulating water purified by the multi-medium filter, forming a turbulent gas-liquid mixed flow. At the same time, the multi-medium filter intercepts particles with a particle size > 10 μm and oil in the exhaust gas; ; (2) Cavitation reaction stage: the gas-liquid mixed flow enters the high-pressure centrifugal pump, and is pressurized by multiple impellers, and the high-pressure gas-liquid mixed flow enters the multi-stage cavitation reactor to form a large number of cavitation bubbles in the gradually scaled cavities, and high-concentration radicals, oxidized decomposition , , , and other pollutants are generated; (3) Post-processing stage: After the reaction, the mixed solution enters the nanoceramic membrane separator, and the membrane assembly intercepts the small molecular organic matter and metal ions that are not completely decomposed. The permeate enters the neutralization tank for adjustment Post-standard discharge or reuse; the nanoceramic membrane separator is pulsed backwashed by the circulating water of the neutralization tank every 8 hours to restore the membrane flux, and the backwashing system automatically cleans the membrane assembly every 8 hours.

4. A method of exhaust gas purification treatment based on the hydrodynamic cavitation technology according to claim 3, characterized in that, Also included is a safety interlock control that automatically shuts off the high pressure pump power and activates the pressure relief valve when the system pressure exceeds a set value. The controller automatically shuts off the high pressure pump power and activates the pressure relief valve.

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