Current Trends in Gas Scrubbing Technology: A Look at the Latest Research Papers in 2023
Wet scrubbing towers, long-recognized as effective air purification systems, function much like a natural rainstorm clearing winter smog, leaving behind fresher, cleaner air. In industrial settings, these towers are pivotal in targeting a range of Volatile Organic Compounds.
Each pollutant requires a tailored strategy for effective removal, emphasizing the need for specific designs in wet scrubbing technology.
However, the challenge arises when a wet scrubber designed for one pollutant type is inappropriately applied to another, often leading to suboptimal results. This misapplication highlights the importance of understanding the capabilities and limitations of these systems.
Understanding the capabilities and limitations of wet scrubbing systems is crucial for their effective application in industrial processes. This article, while not exhaustive, aims to highlight significant advancements in the field as reported in the latest 2023 scientific literature. The objective is to share and disseminate findings, thereby enriching the ongoing discourse on this topic. By presenting a selection of recent scientific works, I seek to deepen the understanding of wet scrubbing systems.
I have chosen 5 articles from 2023's scientific literature that I believe are particularly insightful regarding wet absorption systems. Each article offers a different perspective on the subject, contributing insights into the optimization, efficiency, and environmental implications of wet scrubbing technology.
Below an example of wet scrubber system including the step of salt separation:
Article 1: "Experimental and modelling approach to the design of chemical absorption columns with fast gas-liquid reaction: A case-study on flue-gas desulfurization with H2O2 oxidative solutions" by Flagiello et al., Chemical Engineering Research & Design, 2023
This study by Flagiello and colleagues presents an innovative approach to designing chemical absorption columns that facilitate fast gas-liquid reactions. The research, focusing on the absorption of sulfur dioxide (SO2) in aqueous hydrogen peroxide (H2O2) solutions, integrates experimental data with modeling techniques. The key objectives were to assess the solubility of SO2 in H2O2 solutions, understand the mass transfer phenomena, and determine the kinetics of the reaction where SO2 is oxidized to sulfuric acid.
The researchers utilized a lab-scale fed-batch bubble column to collect data on SO2 solubility in various H2O2 concentrations. This was complemented by a thermodynamic model developed and validated in ASPEN PLUS?, which accurately represented the experimental findings. Additionally, kinetic experiments were conducted using a lab-scale falling-film absorber to examine the SO2 mass-transfer rates and the fundamental kinetic aspects of the absorption process.
The study evaluated the physical contribution to the mass-transfer rate, determining gas-side (kGa) and liquid-side (kLa) coefficients in the absorber. Moreover, the Enhancement factor (EL) of the SO2 oxidative absorption in the presence of H2O2 was calculated. The researchers correlated EL to the Hatta number (Ha) using the Danckwerts kinetic model, treating the reaction as a pseudo-mth-nth-order non-reversible type, and derived the model kinetic parameters.
This comprehensive experimental and modeling approach offers insights into the design of reactive absorption columns, particularly for applications like flue-gas desulfurization. The study’s findings contribute to our understanding of the SO2-H2O2 reaction dynamics, providing a robust framework for the design and optimization of similar systems.
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Article 2: "Modeling and experimental studies on chemical absorption of ammonia emitted from poultry manure during the drying process by a wet spray scrubber: Optimization by Box-Behnken design" by Khodadadi et al., Process Safety and Environmental Protection, 2023
This study by Khodadadi and colleagues addresses a significant environmental concern in poultry production: ammonia gas emissions from poultry manure. The research focuses on optimizing the drying process of poultry manure in a hot air dryer and its subsequent effect on ammonia emissions, as well as the efficiency of ammonia absorption using a spray scrubber.
Key variables in the drying process, such as air temperature (60–80 °C), air relative humidity (8–18%), manure depth (2–4 cm), and air velocity (2–3 m/s), were analyzed to optimize ammonia emission reduction. Additionally, the absorption process was optimized by examining the effects of absorbent solution temperature (30–50 °C), solution pH (2?4), and nozzle operating pressure (0.2–0.6 Mpa). The Box–Behnken design was utilized to find the optimal conditions for both processes.
The findings revealed that manure depth significantly affected both the drying duration and ammonia emission, with deeper manure layers and lower air velocities and temperatures increasing ammonium nitrogen losses. The optimal conditions for minimizing ammonium nitrogen losses were identified as an air temperature of 60 °C, air relative humidity of 8.11%, manure depth of 3.95 cm, and air velocity of 2 m/s.
In terms of ammonia absorption, the study found that the temperature of the absorbent solution and the solution pH had contrasting effects on absorption efficiency. Higher nozzle operating pressure was found to enhance ammonia absorption. The maximum absorption was achieved at a solution temperature of 49.2 °C, solution pH of 2, and nozzle operating pressure of 0.58 Mpa, resulting in an ammonium sulfate concentration of 9.09 g/l in the absorbent solution and a spray scrubber efficiency of 66.79%.
This research provides insights into controlling ammonia emissions from poultry manure, highlighting that varying the investigated variables can effectively manage both emissions and absorption of ammonia.
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Article 3: "Wet scrubbing process with oxidation and reduction in series for removal of SO2 and NO from marine diesel engine exhaust" by Chin et al., Chemical Engineering Journal, 2023
In this article, Chin, Tam, and Yin explore a novel wet scrubbing technique designed for removing SO2 and NOx from simulated ship emissions. The scrubber system they investigate consists of an oxidation section and a reduction section, working in series. Sodium chlorite (NaClO2) is used in the oxidizing section, while sodium thiosulfate (Na2S2O3) is employed in the reducing section.
The study finds that increasing the pH in the sodium chlorite oxidant section results in reduced nitrogen oxide oxidation, leading to lower rates of soluble nitrogen formation, primarily in the form of nitrates. Additionally, the consumption rate of the reactant per mole of pollutant removed is also lower. On the reduction side, sodium thiosulfate is found to be less efficient than sodium sulfite (Na2SO3) in removing NO2, but it consumes reactants more slowly and produces very little soluble nitrogen.
One of the key observations is that sodium thiosulfate forms sulfur precipitates during the reaction, which can be managed by operating at a higher pH. This approach allows for a portion of the scrubber's washwater to be safely discharged into the ocean without exceeding nitrate limits, by adjusting the oxidation potential through mixing water from both the oxidation and reduction sections.
This study contributes to the understanding of how wet scrubbing, combined with appropriate chemical reactions, can effectively reduce harmful emissions from marine diesel engines, offering a potential solution for managing pollution in maritime transport.
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Article 4: "Digital twin-based optimization and demo-scale validation of absorption columns using sodium hydroxide/water mixtures for the purification of biogas streams subject to impurity fluctuations" by Pallavicini et al., Renewable Energy, 2023
Pallavicini and his team's research focuses on the validation of demo-scale plant scrubber technology for the purification of biogas, particularly targeting the removal of hydrogen sulfide (H2S) using sodium hydroxide (NaOH). The study involves an experimental campaign complemented by the development of a digital twin, a virtual model designed to replicate and analyze the real-world operations of the scrubber.
The absorber unit, using a 30% w/w sodium hydroxide solution as the wet agent, treats 300 Nm3/h of biogas with varying H2S concentrations ranging from 1000 to 3000 ppm. Field measurements were conducted to assess the efficiency of H2S removal. The data collected from these measurements were then used to develop a digital twin in the Aspen PLUS suite, enabling the simulation of operating conditions different from those at the demo-scale plant.
A key aspect of the study is the use of this digital twin for a sensitivity analysis to identify the main variables affecting H2S removal efficiency. Factors such as H2S concentration, soda concentration and flowrate, temperature, and freshwater flowrate were examined. The results showed that the NaOH flowrate and its concentration significantly impact the process, with the highest efficiency achieved using a 50% NaOH solution at a flowrate exceeding 8 kg/h.
The work highlights the importance and effectiveness of using a digital twin for optimizing biogas scrubbing technology. It is noted that the discrepancy between the on-field unit and its digital twin was consistently less than 6%. This approach allows for a broader assessment of the plant's performance under various conditions, proving particularly useful in optimizing the biogas scrubbing process. The findings emphasize NaOH flowrate as the most influential parameter for the efficiency of biogas scrubbing removal.
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Article 5: "Numerical Analysis of SO2 Absorption inside a Single Water Drop" by Amoresano et al., Atmosphere, 2023
In this paper, Amoresano and his team develop a numerical model to simulate the absorption of sulfur dioxide (SO2) in the context of the interaction between combustion gases and water droplets. The focus of the research is on understanding the chemical and physical parameters that govern the mass transfer in these interphase interactions.
A key aspect of the study is the granulometric curve of sprays, particularly the minimum droplet size that is crucial for the effective operation of wet scrubbers. The findings highlight a critical diameter below which the effectiveness of the spray diminishes under various boundary conditions. Notably, the research discovered that a single droplet with a maximum diameter of 2 mm absorbs more SO2 compared to smaller droplets, reaching a peak absorption of 4.36 × 10^?5 grams of SO2 within the simulation timeframe.
Additionally, the study examines the impact of water mass on the absorption process. It was found that smaller droplets, such as those with a diameter of 1 mm, significantly enhance the absorption process. These smaller droplets achieved a SO2 absorption quantity that was over 5.77 times greater than that of a 2 mm droplet.
This research offers a preliminary tool for optimizing droplet distribution in sprays, aiming to improve the overall capture efficiency. The insights gained from this study are particularly valuable for the design of efficient wet scrubber systems, which are essential for controlling pollution in both industrial and environmental settings. The paper serves as a guide for future advancements in the field of wet scrubbing technology, especially in terms of optimizing droplet size for maximum absorption efficiency.
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??These are the papers I found most compelling, but my purpose is to foster a collaborative exchange of knowledge. If you have further insights, questions, or would like to highlight other noteworthy articles in this field, I warmly invite you to share your thoughts in the comments below.
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3 周Respected sir, My design is very simple. I am thermophilic biogasplant plant designer. In my design biogas pass through a cyclone separator. Cyclone upper diameter is 8" . Bottom diameter 12". Drain pipe is 2" .Drain pipe makes 'U' loop This u loop length is 5 feet long. U loop comeback to upper level of U loop. In this condition it is impossible to be empty.. Biogas pressure is always more Than 4"of water gauge. Cyclone separator out let goes to bubble scrubber. Bubble scrubber diameter is 10 ". It's outlet diameter is 2". Drain point is connected to bottom at apposite side. From bottom it sheped U loop and goes to drain. Inverted U loop length is 6" Bubble scrubber inlet pipe is below 2.5"below actual level in bubble scrubber, means bubble scrubber never can be empty. Bubble scrubber to be filled with lime water. Bubble scrubber water Ph value
President at Enviroenergy Solutions, Inc.
10 个月Hi, Matteo Any scrubbing system that is using packed towers in real industrial setting can get plugged by particles and can benefit from low pressure drop (25 mm. w.c.) high efficiency cleaning section upstream like our proprietary WESP module. The cold plasma generated by Corona discharge inside this section is oxidizing NO among other positive side effects that can lower the consumption of chemicals for instance at Marine diesel application. Also WESP is the perfect separator of H2SO4 droplets from the gas that can be collected in separate collecting tank and not to be drained in to Ocean thus improving water treatment of the system for scrubbers in Marine Diesel exhaust applications. More information about our technology is on www.enviroenergytech.com With specific questions you can call me at 1-917-640-4453