Ship tail gas integrated treatment device and method integrating waste heat recovery function and multi-pollutant collaborative purification

Abstract

The invention provides a ship tail gas integrated treatment device and method integrating a waste heat recovery function and multi-pollutant collaborative purification. The ship tail gas integrated treatment device comprises a pretreatment module, a waste heat recovery module, a collaborative oxidation module, an absorption purification module, a medicament circulation module and an intelligent control module which are integrated in a closed shell and sequentially communicate with one another. According to the invention, the core defects of poor collaboration, insufficient ship adaptability and high operation cost of the traditional technology are solved. According to the device, impurities are removed through the pretreatment module, the reaction working condition is optimized through the waste heat recovery module, the pollutant activity is improved through the cooperation of the oxidation module, efficient absorption is achieved through the absorption and purification module, the intelligent control module adapts to working condition fluctuation, and finally the dual purposes of emission reduction and energy conservation are achieved. A real ship test shows that the device is high in purification efficiency, stable in operation and good in economical efficiency, can be widely applied to tail gas treatment of various ships, and has remarkable environmental value, economic value and industrial popularization value.

Description

Technical Field

[0001] This invention belongs to the field of ship exhaust gas treatment and energy recovery, specifically relating to an integrated ship exhaust gas treatment device that integrates waste heat recovery and multi-pollutant synergistic purification. Background Technology

[0002] Marine diesel engines use diesel fuel as their primary fuel, and their exhaust contains a large number of pollutants, mainly NO. x SO x PM and unburned hydrocarbons (HC), etc. To control ship exhaust pollution, Annex VI of the IMO MARPOL Convention addresses NOx emissions from ships. x and SO x Strict emission standards have been established, with Tier III standards requiring ships to maintain NOx emissions within Emission Control Areas (ECAs). x Emission concentrations are reduced by more than 80% compared to Tier I, SO2 x Emission concentrations must be below 0.1%. Traditional single-function exhaust gas treatment devices can no longer meet current technical and policy requirements.

[0003] Currently, most ship exhaust gas treatment technologies adopt a "module-based independent treatment" model, which has the following core drawbacks: Poor synergy in treating multiple pollutants: In existing technologies, NO... x The treatment often employs selective catalytic reduction (SCR), SO x Treatment methods include seawater washing or alkaline liquid absorption, while PM treatment employs electrostatic precipitators or bag filters. Each module operates independently, lacking a coordinated design. For example, SCR catalysts are easily degraded by SO₂. x Poisoning and inactivation necessitate the addition of a desulfurization module before the SCR, resulting in a lengthy system process; PM accumulation can clog the filter media in the scrubbing tower, affecting desulfurization efficiency, and severe interference between modules.

[0004] Waste heat from exhaust gas is not effectively utilized: The temperature of marine diesel engine exhaust gas is typically 200-400℃, containing a large amount of recoverable heat energy. Existing treatment devices only focus on pollutant removal and do not integrate waste heat recovery with the purification process, resulting in energy waste. Some ships are equipped with separate waste heat boilers, but these are arranged independently from the exhaust gas treatment system, occupying a large amount of ship space, and the efficiency of waste heat recovery is greatly affected by fluctuations in exhaust gas temperature.

[0005] Insufficient ship adaptability: The limited space and strict center of gravity control on ships, coupled with large fluctuations in diesel engine load (20%-100%), make it difficult to adapt to traditional large-scale, fixed-condition treatment devices. For example, traditional SCR devices are bulky and require frequent catalyst replacement; seawater scrubbing towers consume a large amount of water, limiting their application on ocean-going vessels with limited freshwater reserves; and the complex piping connections between individual modules increase the operational risks under ship vibration.

[0006] High operating costs: The combined effects of equipment investment in individual modules, reagent consumption (such as ammonia reducing agent in SCR), and energy consumption (such as high-voltage power supply for electrostatic precipitators) result in persistently high operating costs. Furthermore, the lack of coordination between modules leads to low reagent utilization; for example, alkaline wastewater generated during desulfurization cannot be recycled to other modules, increasing wastewater treatment costs. Summary of the Invention

[0007] 1. The technical problem to be solved: How to overcome the shortcomings of existing ship exhaust gas treatment technologies, such as independent operation of multiple modules, poor coordination, waste of waste heat, and insufficient ship adaptability.

[0008] 2. Technical Solution: To address the above problems, this invention provides an integrated ship exhaust gas treatment device that integrates waste heat recovery and multi-pollutant synergistic purification. The device comprises a pretreatment module, a waste heat recovery module, a synergistic oxidation module, an absorption and purification module, a reagent circulation module, and an intelligent control module, all integrated within a sealed housing and sequentially connected via a flue gas channel and pipeline system.

[0009] The pretreatment module separates most of the diesel mist droplets and large-diameter PM particles through an inertial demister, filters fine PM particles through a metal filter, and achieves uniform airflow distribution through an airflow distributor.

[0010] The waste heat recovery module exchanges heat with the exhaust gas after it has been pretreated. The heated heat transfer oil is then transported to the oil storage tank and distributed to the ship's auxiliary energy system. PM that settles during the heat exchange process falls into the ash hopper and is discharged periodically.

[0011] The co-oxidation module mixes the cooled exhaust gas, ozone, and NO in the co-oxidation module (4) and oxidizes them into high-valence nitrogen oxides.

[0012] The absorption and purification module sprays alkaline absorbent liquid onto the tail gas entering the absorption and purification module (5) in a counter-current contact with the packing layer, SO x High-valence nitrogen oxides absorb liquid reaction.

[0013] The reagent circulation module utilizes the waste heat from the waste heat recovery module to evaporate and concentrate solid salt byproducts; based on the pH and concentration data of the slurry tank, it automatically replenishes NaOH and Na2CO3 to maintain the stability of the absorbent performance.

[0014] The intelligent control module collects data from various sensors and diesel engine load information in real time, and adjusts the ozone generator power, circulation pump flow rate, and reagent replenishment parameters through the PLC controller to ensure stable operation of the device under different working conditions.

[0015] The present invention also provides an integrated treatment method for ship exhaust gas that integrates waste heat recovery and multi-pollutant synergistic purification, using the aforementioned integrated treatment device for ship exhaust gas that integrates waste heat recovery and multi-pollutant synergistic purification.

[0016] 3. Beneficial effects: This invention, through an integrated structural design, achieves a deep fusion of waste heat recovery from ship exhaust gas and synergistic treatment of multiple pollutants, overcoming the core shortcomings of traditional technologies such as poor synergy, insufficient ship adaptability, and high operating costs. The device removes impurities through a pretreatment module, optimizes reaction conditions through a waste heat recovery module, enhances pollutant activity through a synergistic oxidation module, achieves efficient absorption through an absorption and purification module, and adapts to fluctuations in operating conditions through an intelligent control module, ultimately achieving the dual goals of "emission reduction + energy saving." Real-ship testing demonstrates that this device has high purification efficiency, stable operation, and good economic performance, and can be widely applied to exhaust gas treatment of various types of ships, possessing significant environmental, economic, and industry promotion value. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the present invention.

[0018] Explanation of reference numerals in the attached drawings: 1. Shell; 2. Pretreatment module; 3. Waste heat recovery module; 4. Co-oxidation module; 5. Absorption and purification module; 6. Reagent circulation module; 7. Intelligent control module. Detailed Implementation

[0019] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0020] like Figure 1 As shown, an integrated ship exhaust gas treatment device that integrates waste heat recovery and multi-pollutant synergistic purification includes a pretreatment module 2, a waste heat recovery module 3, a synergistic oxidation module 4, an absorption and purification module 5, a reagent circulation module 6, and an intelligent control module 7, all integrated in a sealed shell 1 and connected sequentially through a flue gas channel and pipeline system.

[0021] This invention integrates pretreatment, waste heat recovery, synergistic oxidation, and absorption purification functional modules into a single sealed shell. Employing a modular and detachable design, it reduces volume by 60% and weight by 50% compared to the traditional "independent module + complex piping" structure. The shell is made of corrosion-resistant stainless steel with anti-corrosion treatment, adapting to ship vibration and marine corrosion environments. The modules are connected via quick-connect couplings, facilitating onboard installation and maintenance, thus solving the problems of large size, inconvenient installation, and poor vibration resistance of traditional devices.

[0022] In one embodiment, the pretreatment module 2 is located at the inlet end of the device and is connected to the exhaust pipe of the marine diesel engine via a flange. It includes an inertial demister, a metal filter, and an airflow distributor arranged in sequence.

[0023] The inertial demister adopts a baffle structure, which uses centrifugal force to separate a large number of diesel mist droplets and large-diameter PM particles carried in the exhaust gas. The particle size is ≥10μm and the removal efficiency is ≥90%, thus avoiding the subsequent modules from being blocked by oil.

[0024] The metal filter is made of 316L stainless steel with a pore size of 50μm, which further filters PM particles with a diameter of 5-10μm, and can be disassembled and cleaned regularly. The airflow distributor has a perforated plate structure with an opening rate of 60%, which ensures that the flue gas flow rate entering the subsequent modules is uniform and avoids efficiency fluctuations caused by local airflow impact.

[0025] In one embodiment, the waste heat recovery module 3 is adjacent to the pretreatment module and adopts a "flue gas-heat transfer oil" heat exchange structure, including a heat exchange cavity, a spiral heat exchange tube, a heat transfer oil circulation pump and an oil storage tank.

[0026] The heat exchange chamber has a cylindrical structure. Flue gas enters from the bottom of the chamber and exits from the top, forming a reverse heat exchange with the heat transfer oil in the heat exchange tube. The heat exchange area is increased by 40% compared with the traditional shell and tube heat exchanger.

[0027] The spiral heat exchange tube adopts a finned design with a fin spacing of 5mm. It is made of high-temperature resistant nickel alloy and can withstand a high temperature of 450℃, avoiding corrosion from sulfides in the exhaust gas. The heat transfer oil is a synthetic heat transfer oil with good high-temperature stability (operating temperature range -20℃ to 350℃). It circulates in the heat exchange tube and absorbs the waste heat of the exhaust gas, raising the temperature from 100℃ to 250℃.

[0028] The oil storage tank is connected to the ship's auxiliary energy system. The heated heat transfer oil can be used for heating the ship's domestic water, preheating fuel oil, or driving a small ORC generator set to generate electricity. The waste heat recovery efficiency is over 75%, and a single 10,000 kW diesel engine can recover approximately 1,200 kW of heat energy. The heat exchange chamber is equipped with an ash hopper at the bottom to collect PM that settles during the heat exchange process. The ash hopper is tilted at a 60° angle to facilitate ash discharge and avoid ash accumulation that could affect the heat exchange efficiency.

[0029] In one embodiment, the synergistic oxidation module 4 is located at the outlet side of the waste heat recovery module. It utilizes the recovered waste heat to cool the flue gas to 180-220°C, which is the optimal temperature range for ozone oxidation of NO, thus achieving NO oxidation. x Synergistic oxidation with PM includes an oxidation chamber, an ozone generator, a jet mixer, and a catalytic enhancement layer.

[0030] The ozone generator uses low-temperature plasma technology and ship compressed air as raw material. The ozone output can be adjusted in real time according to the NO concentration in the flue gas, with an adjustment range of 0-500g / h. The ozone concentration is stable at 8%-12%, and the energy consumption is reduced by 30% compared with traditional ozone generators. The jet mixer is located at the inlet of the oxidation chamber and adopts a Venturi structure to inject ozone into the flue gas in a high-speed jet manner with a flow rate ≥20m / s, so that the mixing time of ozone and flue gas is ≤0.5s and the mixing uniformity is ≥95%, ensuring that NO is fully oxidized into easily absorbed high-valence nitrogen oxides such as NO2 and N2O3. The catalytic enhancement layer is located in the middle of the oxidation chamber. The carrier is a honeycomb ceramic and loaded with a MnO2-CeO2 composite catalyst. It can catalyze the reaction between ozone and carbon particles in PM, oxidize the carbon particles into CO2, and at the same time improve the oxidation efficiency of ozone on NO, increasing the NO oxidation rate from 70% to over 90% of ozone oxidation alone. The oxidation chamber outlet is equipped with a temperature sensor and a NO concentration sensor to monitor flue gas parameters in real time and provide data support for intelligent control.

[0031] In one embodiment, the absorption and purification module 5 is connected to the synergistic oxidation module and adopts an integrated structure of "spray-filler-demisting" to simultaneously absorb SO using alkaline absorbent. x and oxidized NO x It includes an absorption tower, a spray layer, honeycomb packing, a demister, and a slurry tank.

[0032] The absorption tower has a counter-current structure. Flue gas enters from the bottom of the tower and comes into counter-current contact with the absorbent sprayed in the spray layer. The absorbent is a mixed solution of NaOH and Na2CO3 (mass concentration 5%-8%), which can simultaneously react with SO2 to produce Na2SO3 and with NO2 to produce NaNO2 and NaNO3, thus achieving SO2 absorption. x with NO x Synergistic absorption.

[0033] The spray layer consists of three layers, each with 12 high-pressure atomizing nozzles. The atomized particle size is 50-80 μm, and the spray density is 15 m³ / (m²·h), ensuring that the absorbent forms a uniform liquid film on the surface of the packing layer. The honeycomb packing is made of polypropylene with a specific surface area ≥200 m² / m³, increasing the gas-liquid contact area and reducing SO₂ concentration. x Absorption rate ≥98%, NO x Absorption rate ≥85%.

[0034] The demister is located at the top of the absorption tower and adopts a corrugated plate structure. It has a demister efficiency of ≥99%, which avoids secondary pollution caused by the absorption liquid droplets being emitted with the exhaust gas.

[0035] The slurry tank is located at the bottom of the absorption tower and has a built-in stirrer and pH sensor. The stirrer rotates at 50 r / min to ensure uniform concentration of the absorbent and control the pH value between 8 and 10, providing a suitable alkaline environment for the absorption reaction.

[0036] This invention breaks through the traditional model of "independent waste heat recovery and purification" and deeply couples waste heat recovery with the synergistic oxidation process: by using waste heat recovery to reduce the exhaust gas temperature to 180-220℃, which is exactly the optimal reaction temperature for ozone oxidation of NO, the NO oxidation efficiency is increased by more than 20% compared with traditional room temperature ozone oxidation; at the same time, the recovered waste heat is used for absorption liquid crystallization and concentration, reducing the additional energy consumption of the crystallization process, and realizing the synergistic effect of "waste heat recovery-oxidation efficiency enhancement-energy consumption reduction".

[0037] Furthermore, in the synergistic oxidation module, NO is achieved through a catalytic enhancement layer. x In synergy with PM, ozone is used to oxidize both NO and carbon particles. Compared with the traditional process of "dust removal first and then denitrification", it reduces the equipment investment of independent dust removal modules, while improving ozone utilization and reducing reagent consumption by 30%.

[0038] In one embodiment, the reagent circulation module 6 realizes the recycling of the absorbent and the recovery of by-products, including a circulation pump, a filter, a crystallizer and a reagent replenishment pump.

[0039] The circulating pump transports the absorbent liquid in the slurry tank to the spray layer. The circulation flow rate is adjusted according to the flue gas volume, with an adjustment range of 50-150 m³ / h, so that the absorbent liquid can be recycled within the system, reducing the consumption of fresh reagents.

[0040] The filter adopts a bag filter structure with a filtration accuracy of 10μm, removing fine PM particles and precipitates generated in the absorption liquid, thus avoiding nozzle clogging.

[0041] The crystallizer is connected to the slurry tank. When the total concentration of Na2SO3, NaNO2, and NaNO3 in the absorbent reaches 25%, the absorbent is introduced into the crystallizer. Through evaporation and concentration, solid salt by-products are generated using part of the waste heat from the waste heat recovery module. These by-products can be recycled as industrial raw materials, thus realizing the resource utilization of pollutants. The reagent replenishment pump automatically replenishes NaOH and Na2CO3 to the slurry tank based on the detection data from the pH sensor and concentration sensor, ensuring the stability of the absorbent performance.

[0042] This invention achieves the recycling of the absorbent liquid through a reagent circulation module, reducing the consumption of fresh reagents by 60% compared to traditional absorption devices. At the same time, it converts the Na2SO3, NaNO2, and NaNO3 generated in the absorption reaction into solid salt byproducts, which can be recycled as industrial raw materials, avoiding the problem of alkaline waste liquid discharge generated by traditional devices, realizing the transformation of "pollutants into resources", and meeting the green and environmentally friendly requirements of ships.

[0043] In one embodiment, the intelligent control module 7 is the core control unit of the device, including a PLC controller, a sensor group and an actuator, to realize full-process automated control.

[0044] The sensor group includes a flue gas flow sensor, a temperature sensor, and a PM concentration sensor installed at the inlet of the pretreatment module; a temperature sensor at the outlet of the waste heat recovery module; an NO concentration sensor and an ozone concentration sensor at the outlet of the co-oxidation module; and an NO concentration sensor at the outlet of the absorption tower. x Concentration sensor, SO x Concentration sensors, as well as pH and concentration sensors in the slurry tank, transmit all sensor data to the PLC controller in real time.

[0045] The PLC controller is connected to the marine diesel engine ECU (electronic control unit) via a CAN bus to obtain diesel engine load information, predict flue gas parameter fluctuations based on load changes, and adjust the operating parameters of each module in advance.

[0046] The actuators include a power regulator for the ozone generator, a frequency converter for the circulating pump, a metering valve for the reagent replenishment pump, and a controller for the heat transfer oil circulating pump. The PLC controller adjusts the actuators using a PID algorithm based on sensor data and diesel engine load information, so that the device can maintain stable purification efficiency and waste heat recovery efficiency even when the diesel engine load fluctuates between 20% and 100%.

[0047] The intelligent control module of this invention is linked with the diesel engine ECU, acquiring diesel engine load information via the CAN bus to achieve "predictive regulation," which improves response speed by 50% compared to traditional "passive regulation." When the diesel engine load increases from 20% to 100%, the device can adjust parameters such as ozone dosage and circulation pump flow rate within 2 seconds to ensure NO... x The purification efficiency remains stable at over 90%, solving the problem of significant drop in purification efficiency of traditional devices when ship operating conditions fluctuate.

[0048] This invention also provides an integrated treatment method for ship exhaust gas that integrates waste heat recovery and multi-pollutant synergistic purification. The integrated treatment device for ship exhaust gas that integrates waste heat recovery and multi-pollutant synergistic purification is characterized by the following steps: Step 1: Exhaust Gas Pretreatment: The exhaust gas from marine diesel engines, with a temperature of 250-400℃, contains NO. x SO x PM and diesel mist droplets enter the pretreatment module. First, most of the diesel mist droplets and large-diameter PM are separated by an inertial demister. Then, fine PM is filtered by a metal filter. Finally, the airflow is evenly distributed by an airflow distributor. The PM removal rate of the pretreated exhaust gas is ≥95%.

[0049] Step 2: Waste Heat Recovery: The pretreated exhaust gas enters the heat exchange chamber of the waste heat recovery module and undergoes counter-current heat exchange with the heat transfer oil in the spiral heat exchange tube. The exhaust gas temperature drops to 180-220℃, while the heat transfer oil temperature rises from 100℃ to 250℃. The heated heat transfer oil is then transported to the oil storage tank and distributed to the ship's auxiliary energy system. PM that settles during the heat exchange process falls into the ash hopper and is discharged periodically.

[0050] Step 3: Co-oxidation: The cooled exhaust gas enters the co-oxidation module. Ozone generated by the ozone generator is injected into the flue gas at high speed through the jet mixer, where it rapidly mixes with NO and oxidizes it into higher valence nitrogen oxides. Simultaneously, under the action of the catalytic enhancement layer, ozone reacts with carbon particles in PM to generate CO2, achieving NO oxidation. x Synergistic oxidation with PM results in NO oxidation rate ≥90% and carbon particle removal rate ≥80%.

[0051] Step Four: Absorption and Purification: The oxidized exhaust gas enters the absorption tower of the absorption and purification module, flowing upwards from the bottom of the tower. It comes into counter-current contact with the alkaline absorbent sprayed in the spray layer within the packing layer, reducing SO₂ levels. x The reaction with the absorbent produces Na₂SO₃, while higher valence nitrogen oxides react with the absorbent to produce NaNO₂ and NaNO₃, thus achieving SO₂ production. x and NO x Simultaneous absorption; the purified exhaust gas is discharged from the top of the absorption tower after the mist droplets are removed by the demister, NO x Concentration ≤50mg / m³, SO x The concentration is ≤10mg / m³, which meets the IMO Tier III emission standard.

[0052] Step 5: Reagent Circulation and Recovery: The absorbent liquid at the bottom of the absorption tower is collected in the slurry tank, pumped to the filter by the circulation pump to remove impurities, and then pumped back into the spray layer for recycling. When the salt concentration in the absorbent liquid reaches 25%, part of the absorbent liquid is introduced into the crystallizer, where the waste heat recovery module is used to evaporate and concentrate it to generate solid salt by-products. At the same time, the reagent replenishment pump automatically replenishes NaOH and Na2CO3 according to the pH value and concentration data of the slurry tank to maintain the stability of the absorbent liquid performance.

[0053] Intelligent control is implemented in all the above steps: the intelligent control module collects data from various sensors and diesel engine load information in real time, and adjusts parameters such as ozone generator power, circulation pump flow rate, and reagent replenishment amount through the PLC controller to ensure stable operation of the device under different working conditions.

[0054] Table 1 shows a performance comparison between the present invention and this device and traditional ship exhaust gas treatment technologies (SCR + seawater scrubbing + electrostatic precipitator + independent waste heat boiler): Table 1. Performance Comparison Table

[0055] This invention can remove NO from ship exhaust gas x SO x The emission concentrations of PM2.5, PM2.5, and PM2.5 are controlled below 50 mg / m³, 10 mg / m³, and 5 mg / m³ respectively, which are far below the IMO Tier III standard, effectively reducing air pollution in ports and coastal areas and contributing to the "Blue Sky Protection Campaign" and marine ecological protection. The single 10,000 kW diesel engine matching device of the present invention can recover about 10 million kWh of waste heat per year, which is equivalent to saving about 800,000 yuan in fuel costs; at the same time, the consumption of reagents is reduced by 30%, which can reduce reagent costs by about 500,000 yuan per year, and the recovery of by-products can generate an additional revenue of about 200,000 yuan, resulting in significant economic returns. This invention solves the compatibility and economic bottlenecks of traditional ship exhaust gas treatment technologies, provides competitive product solutions for ship environmental protection equipment manufacturers, promotes the transformation of the ship environmental protection industry from "single emission reduction" to "emission reduction + energy conservation" synergistic development, and helps the international shipping industry achieve the goal of "carbon neutrality". Example

[0056] Taking a certain ocean-going container ship as an example, its main engine is a MAN B&W 12K98ME-C diesel engine with a power of 18,000 kW. Its exhaust emission parameters are as follows: flue gas volume 15,000 m³ / h, exhaust gas temperature 320℃, NO₂... x Initial concentration 1200 mg / m³, SO x Initial concentration: 1800 mg / m³ (using low-sulfur fuel oil, sulfur content 0.1%), initial PM concentration: 200 mg / m³, diesel mist content: 80 mg / m³. This device is custom-designed for this vessel, with specific parameters as follows: Overall dimensions of the device: 4.5m long × 2.0m wide × 3.5m high, weight 8000kg, shell material is 316L stainless steel, and anti-corrosion coating is epoxy resin.

[0057] Pretreatment module: 5 inertial demister baffles, 50μm metal filter mesh, 60% opening rate of airflow distributor; Waste heat recovery module: 20 heat exchange tubes, each 3.0m long, 50mm in diameter, and 5mm fin spacing; heat transfer oil circulation flow rate 100m³ / h; oil storage tank volume 1.5m³.

[0058] Synergistic oxidation module: ozone generator power 50kW, ozone output 300g / h; jet mixer venturi tube diameter 150mm; catalytic enhancement layer honeycomb ceramic carrier volume 0.8m³, MnO2-CeO2 loading 10%.

[0059] Absorption and purification module: absorption tower diameter 1.5m, height 4.0m; 3 spray layers, 36 nozzles, atomized particle size 50-80μm; packing layer height 1.5m, honeycomb packing specific surface area 200m² / m³.

[0060] The reagent circulation module has a circulation pump flow rate of 120 m³ / h and a filter accuracy of 10 μm; a crystallizer evaporation area of ​​5 m² and an evaporation rate of 0.5 m³ / h; and a reagent replenishment pump with a metering accuracy of ±1%.

[0061] Intelligent control module: The PLC controller is a Siemens S7-1200, the sensor sampling frequency is 1Hz, and the PID adjustment response time is ≤0.5s.

[0062] The device underwent a three-month on-ship trial on the container ship, and the test results are as follows: Purification efficiency: When the diesel engine load fluctuates between 20% and 100%, the NO of the device... x The purification efficiency remains stable at 92%-95%, SO x The purification efficiency remained stable at 98%-99%, and the PM purification efficiency remained stable at 98%-99%; the final exhaust emission concentration was NO. x 42mg / m³, SO x 8 mg / m³ and PM 3 mg / m³ both meet the IMO Tier III standard.

[0063] Waste heat recovery effect: After heat exchange, the temperature of the exhaust gas drops to 200℃, the temperature of the heat transfer oil rises from 100℃ to 250℃, the waste heat recovery power is stable at 1800kW, and 43200kWh of waste heat is recovered every day. It is used for heating the ship's domestic water and preheating the fuel oil, reducing fuel consumption by about 60 tons per month, which is equivalent to about 480,000 yuan in fuel costs.

[0064] Operational stability: During the 3-month test, the unit operated without failure for 99.5% of the time. Only the metal filter and ash hopper need to be cleaned weekly and the catalyst needs to be checked monthly. The maintenance workload is reduced by 70% compared to traditional units.

[0065] Economic efficiency: During the test, the cost of reagent consumption was 72 yuan / 10,000 m³ of flue gas, which is 38% lower than that of traditional technology; the crystallizer generates about 15 tons of solid salt by-products per month, which can be sold as industrial raw materials and generate about 15,000 yuan in revenue.

[0066] Environmental adaptability: During ship navigation, the device is subjected to vibration acceleration ≤5g, and the shell is free from corrosion and deformation; in an environment with seawater humidity of 85%-95%, the electrical system operates normally without short circuit faults.

[0067] Based on actual ship testing, the optimization range of the key parameters of this device was determined as follows: Synergistic oxidation module: The optimal molar ratio of ozone to NO is 1.2-1.5:1, and the optimal temperature range of the catalytic enhancement layer is 180-220℃, at which point the NO oxidation rate is highest.

[0068] Absorption and purification module: The optimal pH range for the absorbent is 8-10, and the optimal spray density is 15-18 m³ / (m²·h). At this point, SO₂... x and NO x It has the highest absorption efficiency.

[0069] Waste heat recovery module: The optimal ratio of heat transfer oil circulation flow rate to flue gas volume is 8:1 (m³ / h:m³ / h), at which point the heat exchange efficiency is the highest and the energy consumption is the lowest.

Claims

1. An integrated ship exhaust gas treatment device that integrates waste heat recovery and multi-pollutant synergistic purification, characterized in that: It includes a pretreatment module (2), a waste heat recovery module (3), a synergistic oxidation module (4), an absorption and purification module (5), a reagent circulation module (6), and an intelligent control module (7) that are sequentially connected through a flue gas channel and a pipeline system and are integrated in a sealed shell (1). The pretreatment module (2) separates most of the diesel mist droplets and large-diameter PM through an inertial demister, filters fine PM through a metal filter, and achieves uniform airflow distribution through an airflow distributor. The waste heat recovery module (3) exchanges heat with the exhaust gas after it has been pretreated and enters the waste heat recovery module (3). The heated heat transfer oil is transported to the oil storage tank and then distributed to the ship's auxiliary energy system. The PM that settles during the heat exchange process falls into the ash hopper and is discharged periodically. The co-oxidation module (4) mixes the cooled exhaust gas, ozone, and NO in the co-oxidation module (4) and oxidizes them into high-valence nitrogen oxides. The absorption and purification module (5) sprays alkaline absorbent liquid onto the exhaust gas entering the module (5) in a counter-current contact with the packing layer, SO x , high-valence nitrogen oxides absorption liquid reaction; The reagent circulation module (6) uses the waste heat of the waste heat recovery module to evaporate and concentrate solid salt byproducts; according to the pH value and concentration data of the slurry tank, it automatically replenishes NaOH and Na2CO3 to maintain the stability of the absorption liquid performance; The intelligent control module (7) collects data from various sensors and diesel engine load information in real time, and adjusts the ozone generator power, circulation pump flow rate, and reagent replenishment parameters through the PLC controller to ensure stable operation of the device under different working conditions.

2. The integrated waste heat recovery and multi-pollutant synergistic purification device for ship exhaust gas as described in claim 1, characterized in that: The pretreatment module (2) is located at the inlet end of the device and is connected to the exhaust pipe of the marine diesel engine. It includes an inertial demister, a metal filter and an airflow distributor arranged in sequence. The inertial demister adopts a baffle structure and uses centrifugal force to separate a large number of diesel mist droplets and particles with a diameter ≥10μm PM carried in the exhaust gas. The metal filter screen has a pore size of 50μm, which further filters PM particles with a particle size of 5-10μm. The airflow distributor is a perforated plate structure with an opening rate of 60%.

3. The integrated waste heat recovery and multi-pollutant synergistic purification device for ship exhaust gas as described in claim 2, characterized in that: The waste heat recovery module (3) is adjacent to the pretreatment module (2) and includes a heat exchange chamber, a spiral heat exchange tube, a heat transfer oil circulation pump, and an oil storage tank. Flue gas enters from the bottom of the cavity and exits from the top. An ash hopper is installed at the bottom of the cavity to collect PM that settles during the heat exchange process. The spiral heat exchange tubes are installed inside the wall and feature a finned design with a fin spacing of 5mm. The material is a high-temperature resistant nickel alloy that can withstand temperatures up to 450℃. The oil storage tank is connected to the ship's auxiliary energy system. The heated heat transfer oil is used for heating the ship's domestic water, preheating fuel oil, or driving a small ORC generator set to generate electricity.

4. The integrated waste heat recovery and multi-pollutant synergistic purification device for ship exhaust gas as described in claim 3, characterized in that: The synergistic oxidation module (4) is located on the outlet side of the waste heat recovery module and includes an oxidation chamber, an ozone generator, a jet mixer, and a catalytic enhancement layer. The ozone generator produces ozone, with the ozone concentration remaining stable at 8%-12%. The jet mixer is located at the inlet of the oxidation chamber and injects ozone into the flue gas in a jet manner with a flow rate of ≥20m / s. The catalytic enhancement layer is located in the middle of the oxidation chamber. The carrier is a honeycomb ceramic, which supports a MnO2-CeO2 composite catalyst to catalyze the reaction between ozone and carbon particles in PM, oxidizing the carbon particles into CO2. The oxidation chamber outlet is equipped with a temperature sensor and a NO concentration sensor to monitor flue gas parameters in real time and transmit them to the intelligent control module.

5. The integrated waste heat recovery and multi-pollutant synergistic purification device for ship exhaust gas as described in claim 4, characterized in that: The absorption and purification module (5) is connected to the synergistic oxidation module and includes an absorption tower, a spray layer, a honeycomb packing, a demister and a slurry tank. The absorption tower is a counter-current structure. The flue gas enters from the bottom of the tower and comes into counter-current contact with the absorbent sprayed by the spray layer. The spray layer is set in 3 layers, with 12 high-pressure atomizing nozzles arranged in each layer. The honeycomb packing is made of polypropylene. The demister is located at the top of the absorption tower and adopts a corrugated plate structure; the slurry tank is located at the bottom of the absorption tower and has a built-in agitator and pH sensor, with the pH value controlled between 8 and 10.

6. The integrated waste heat recovery and multi-pollutant synergistic purification device for ship exhaust gas as described in claim 5, characterized in that: The absorbent is a mixed solution of NaOH and Na2CO3 with a mass concentration of 5%-8%. It reacts with SO2 to produce Na2SO3 and with NO2 to produce NaNO2 and NaNO3, thus achieving SO2 absorption. x with NO x The atomizing nozzle, with an atomizing particle size of 50-80μm and a spray density of 15m³ / (m²·h), and the honeycomb filler made of polypropylene with a specific surface area ≥200m² / m³, enhances the gas-liquid contact area, thereby reducing SO₂ concentration. x Absorption rate ≥98%, NO x Absorption rate ≥85%.

7. The integrated waste heat recovery and multi-pollutant synergistic purification device for ship exhaust gas as described in claim 5, characterized in that: The reagent circulation module (6) includes a circulation pump, a filter, a crystallizer, and a reagent replenishment pump: the circulation pump transports the absorbent liquid in the slurry tank to the spray layer; The filter adopts a bag filter structure with a filtration accuracy of 10μm, removing fine PM and precipitates generated in the absorption liquid; the crystallizer is connected to the slurry tank; the reagent replenishment pump automatically replenishes NaOH and Na2CO3 to the slurry tank according to the detection data of the pH sensor and concentration sensor, ensuring the stability of the absorption liquid performance.

8. The integrated waste heat recovery and multi-pollutant synergistic purification device for ship exhaust gas as described in claim 7, characterized in that: When the total concentration of Na2SO3, NaNO2, and NaNO3 in the absorbent reaches 25%, the absorbent is introduced into the crystallizer, where solid salt byproducts are generated by evaporation and concentration using part of the waste heat recovery module.

9. The integrated waste heat recovery and multi-pollutant synergistic purification device for ship exhaust gas as described in claim 7, characterized in that: The intelligent control module (7) includes a PLC controller, a sensor group and an actuator; the PLC controller is connected to the marine diesel engine ECU via a CAN bus to obtain diesel engine load information; the actuator includes a power regulator for the ozone generator and a frequency converter for the circulating pump, and the parameter adjustment is achieved through a PID algorithm to adapt to 20%-100% diesel engine load fluctuations.

10. An integrated treatment method for ship exhaust gas that integrates waste heat recovery and synergistic purification of multiple pollutants, using the integrated treatment device for ship exhaust gas that integrates waste heat recovery and synergistic purification of multiple pollutants as described in any one of claims 1-9, characterized in that: Includes the following steps: Step 1: Exhaust Gas Pretreatment: The exhaust gas from marine diesel engines, with a temperature of 250-400℃, contains NO. x SO x PM and diesel mist droplets enter the pretreatment module. First, most diesel mist droplets and large-diameter PM are separated by an inertial demister. Then, fine PM is filtered by a metal filter. Finally, the airflow is evenly distributed by an airflow distributor. The PM removal rate of the pretreated exhaust gas is ≥95%. Step 2: Waste Heat Recovery: The pretreated exhaust gas enters the heat exchange chamber of the waste heat recovery module and undergoes counter-current heat exchange with the heat transfer oil in the spiral heat exchange tube. The exhaust gas temperature drops to 180-220℃, while the heat transfer oil temperature rises from 100℃ to 250℃. The heated heat transfer oil is then transported to the oil storage tank and distributed to the ship's auxiliary energy system. PM that settles during the heat exchange process falls into the ash hopper and is discharged periodically. Step 3: Co-oxidation: The cooled exhaust gas enters the co-oxidation module. Ozone generated by the ozone generator is injected into the flue gas at high speed through the jet mixer, where it rapidly mixes with NO and oxidizes it into higher valence nitrogen oxides. Simultaneously, under the action of the catalytic enhancement layer, ozone reacts with carbon particles in PM to generate CO2, achieving NO oxidation. x Synergistic oxidation with PM, at this point, NO oxidation rate ≥90%, carbon particle removal rate ≥80%; Step Four: Absorption and Purification: The oxidized exhaust gas enters the absorption tower of the absorption and purification module, flowing upwards from the bottom of the tower. It comes into counter-current contact with the alkaline absorbent sprayed in the spray layer within the packing layer, reducing SO₂ levels. x The reaction with the absorbent produces Na₂SO₃, while higher valence nitrogen oxides react with the absorbent to produce NaNO₂ and NaNO₃, thus achieving SO₂ production. x and NO x Simultaneous absorption; the purified exhaust gas is discharged from the top of the absorption tower after the mist droplets are removed by the demister, NO x Concentration ≤50mg / m³, SO x Concentration ≤10mg / m³, meeting IMO Tier III emission standards; Step 5: Reagent Circulation and Recovery: The absorbent liquid at the bottom of the absorption tower is collected in the slurry tank, pumped to the filter to remove impurities, and then pumped back into the spray layer for recycling. When the salt concentration in the absorbent liquid reaches 25%, part of the absorbent liquid is introduced into the crystallizer, where the waste heat recovery module is used to evaporate and concentrate it to generate solid salt byproducts. At the same time, the reagent replenishment pump automatically replenishes NaOH and Na2CO3 according to the pH value and concentration data of the slurry tank to maintain the stability of the absorbent liquid performance. Intelligent control is implemented in all the above steps: the intelligent control module collects data from various sensors and diesel engine load information in real time, and adjusts parameters such as ozone generator power, circulation pump flow rate, and reagent replenishment amount through the PLC controller to ensure stable operation of the device under different working conditions.

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