臭氧氧化结合硫代硫酸钠溶液喷淋同时脱硫脱硝

采用臭氧氧化结合湿法喷淋硫代硫酸钠溶液的方法开展模拟烟气同时脱硫脱硝实验研究。结果表明,采用臭氧氧化结合Na2S2O3-Na OH溶液湿法喷淋可以实现NOx和SO_2协同脱除:在O_3/NO摩尔比为1.1~1.2时,溶液中Na2S2O3浓度的增加会提高系统的NO_x脱除效率,烟气中SO2的存在会促进NOx的脱除,当SO2浓度为1030mg·m~(-3)、2.0%Na_2S_2O_3溶液作为喷淋液时可实现较高的SO_2脱除效率,同时NO_x脱除效率可达70%以上;喷淋液p H在2.5~9范围内变化时提高浆液p H有利于NOx的脱除,当p H=9时脱硝效率可达75%。180 min连续同时脱硫脱硝实验结果表明,硫代硫酸钠可有效促进NOx的脱除,并实现SO2较高的脱除效率,同时可实现系统同时脱硫脱硝连续稳定运行,喷淋吸收后烟气中NO_x的主要转化产物为NO~-_2,该方法作为一种有效的同时脱硫脱硝技术,具有一定的工业应用推广前景。     

内插扭带对鼓泡反应器脱硫脱硝效果的影响

在玻璃鼓泡反应器中进行Na₂S₂O₈和H₂O₂两种混合氧化剂吸收SO₂和NO的实验研究,结果表明：在Na₂S₂O₈氧化剂中加入H₂O₂可以促进脱硫脱硝,考虑溶液的成本以及系统的整体脱硫脱硝总效率,选取质量分数为2%的H₂O₂和10%的Na₂S₂O₈混合液具有较高的性价比。基于数值模拟的方法,将扭带引入鼓泡反应器中,研究扭带直径、厚度和扭率对鼓泡反应器脱硫脱硝效率的影响。数值模拟结果表明,与普通鼓泡反应器相比,加入扭带促进脱硫脱硝的效果。脱硫脱硝效率随着扭带直径和扭带厚度的增大而增大,随着扭带扭率的增大而减小,当扭带的直径从16mm增加到24mm时,系统的脱硫率和脱硝率分别增加了3.88%和3.45%;当扭带的厚度从0.2mm增加到1mm时,系统的脱硫率和脱硝率分别增加了4.27%和1.62%;当扭带的扭率从0.25增加到0.75时,系统的脱硫率和脱硝率分别降低了3.91%和1.90%。     

基于气-液传质强化的湿法烟气脱硫CFD模拟研究

针对燃煤电厂烟气脱硫过程中,高硫煤燃烧产生的高含硫烟气高效脱硫难题,通过计算流体力学(CFD)开展了钙法烟气SO₂高效脱除研究,提出了基于塔内筛板构件及喷淋系统优化的多手段耦合增效方法。建立了宏观脱硫塔尺度下涵盖喷淋吸收-筛板鼓泡吸收的SO₂多形式吸收脱除耦合模型,获得了浆液下落过程中的pH及SO₂吸收速率变化规律,并研究了湍流构件对脱硫塔内的气液混合流动、相内相间传质、浆液内部化学反应等过程的影响机制。探究了筛板对于脱硫塔脱除效率的强化机制,并进一步开展了筛板布置位置优化设计研究。同时,针对脱硫塔喷淋系统开展了优化设计研究,通过对比研究获得了喷淋系统优化后布置方案。基于所提出的脱硫塔多手段耦合增效方法,研究了包括液气比、浆液粒径及入口烟气SO₂浓度等不同参数影响下的脱硫塔SO₂脱除性能,发现通过塔内筛板构件及喷淋系统优化多手段协同增效后,可实现不同工况下脱硫塔SO₂脱除效率提升3%～8%。     

燃煤烟气同时脱硫脱硝技术进展

煤炭仍是我国能源的主要原料,其燃烧排放的SO₂和NO_x依然是主要污染源之一。对近期燃煤烟气同时脱硫脱硝的液相吸收技术、紫外高级氧化技术、低温等离子体技术、电子束技术、臭氧前置氧化结合化学吸收技术和干法催化再生技术进行了详细的总结和评述,分析了对SO₂和NO_x脱除效率的影响因素,并对技术的应用进行了展望。     

采用响应面法降低湿法氧化脱硫中Na2S2O3生成量

Na₂S₂O₃是湿法脱硫过程外排废液中最主要的副盐,降低Na₂S₂O₃的生成量对绿色生产具有重要意义。首先采用Plackett-Burman实验筛选出影响Na₂S₂O₃生成量的关键因素,即pH、单质硫浓度、温度。在此基础上运用响应曲面法,以Na₂S₂O₃生成量为目标函数,进行三因素三水平的优化设计分析。研究结果表明,pH对Na₂S₂O₃的影响最大,其次是温度和单质硫浓度,因子间交互作用的影响很小。得到最优的操作条件为pH 8.25,单质硫浓度0.47 g/L,温度31.80℃,PDS浓度90 mg/L,氧硫比1.2 mmol/mmol,此时Na₂S₂O₃生成量为1.838 mmol/L。从Na₂S₂O₃反应动力学和多硫离子的平衡反应两方面对各因素的影响规律进行了解释。最后对实际生产过程进行分析,发现实验得出的pH过低,不利于吸收过程的稳定,现有单质硫熔融分离方法不利于降低脱硫液中的单质硫含量,加速了副盐的生成等问题,对此提出了改进意见,并取得了显著效果。     

降低FCC烟气脱硫高盐水硝酸盐的研究分析

在采用LoTO_x臭氧氧化脱硝+EDV湿法脱硫除尘的完全再生FCC装置,通过试验极限调变脱硝臭氧量,以考察装置烟气脱硫高盐水中硝酸盐浓度的变化规律,摸索研究装置烟气NO_x及外排高盐水中硝酸盐超低近零排放的可行性途径。结果表明：装置O₃/NO摩尔比在1左右臭氧脱硝效率可达到90%左右,O₃/NO摩尔比在0.2左右时臭氧仍可实现48%左右的脱硝效率;臭氧量由60 kg/h降至0 kg/h,烟脱外排高盐水中硝酸盐占硫酸盐比例由1.063%下降至0.33%,硝酸盐占比基本下降至近零水平。     

臭氧低温氧化烟气脱硝过程中的氮平衡试验研究

臭氧氧化污染物协同脱除技术利用臭氧的强氧化性,将烟气中溶解度较低的NO _x 、Hg、VOCs等多种污染物氧化为高价态或易溶解的形式,并结合尾部湿法喷淋系统实现污染物的同时脱除。由于其具有温度窗口低、脱硝效率高、反应速率快及改造难度小等优点,在工业锅炉、窑炉及非电行业得到广泛应用。但是在此过程中的污染物实际转化路径,尤其是氮氧化物的输入/输出平衡,目前还未有详细的验证试验支撑。因此本文针对典型臭氧氧化脱硝过程,对污染物脱除过程中的氮氧化物输入/输出平衡及氮元素流向进行了分析试验。试验结果表明,气相输入的NO经过臭氧氧化耦合湿法喷淋后逐渐转化为液相中硝酸根和亚硝酸根离子。在不同O₃/NO摩尔比下,气相氮元素的减少量均以液相中硝酸根及亚硝酸根的增加量存在,不存在其他含氮形式。同时,吸收浆液中硝酸盐及亚硝酸盐的转化率也与烟气中NO _x 脱除率相匹配。在NO/SO₂同时氧化条件下,调节O₃/NO摩尔比,结合湿法喷淋系统可以实现NO _x /SO₂的协同高效脱除,同时系统满足氮元素输入/输出平衡,为臭氧氧化污染物协同脱除技术的工程应用推广提供了依据。     

等速升温流态化下CaO/生物质焦的SO2/NO联合脱除特性

燃煤锅炉污染物超低排放标准对电厂脱硫和脱硝系统提出了更高的要求。CaO作为脱硫剂可以实现循环流化床锅炉烟气中SO₂的高效脱除,焦炭作为还原剂直接还原NO,同时CaO的存在对焦炭还原NO起催化作用,可以实现燃煤烟气中SO₂/NO的联合脱除。为了探究连续温度变化对CaO/生物质焦联合脱硫脱硝性能的影响,在钙循环捕集CO₂技术背景下,研究了等速升温流态化下CaO/生物质焦的SO₂/NO联合脱除特性。探究了烟气中O₂和CO₂对CaO/椰壳焦脱除SO₂/NO的影响。结果表明,O₂通过对椰壳焦表面碳原子的活化作用降低了异相还原NO温度,在300~950℃等速升温过程中CaO/椰壳焦的NO脱除效率逐渐增加,780℃以上能实现100%脱硝。O₂也提高了CaO/椰壳焦的脱硫效率。CO₂与CaO的碳酸化反应以及与椰壳焦的气化反应对同时脱除SO₂/NO有明显抑制作用。O₂和CO₂共同作用下,在500~800℃内CaO/椰壳焦的脱硝效率随温度升高而增加,脱硫效率先降低后升高。NO促进了CaO/椰壳焦脱除SO₂,而SO₂对脱硝有抑制作用。800℃时CaO/椰壳焦同时脱除SO₂和NO的效率分别为97.7%和93.9%。     

燃煤烟气中SO3迁移转化特性及其控制的研究现状及展望

SO₃排放导致的烟羽浊度增大、蓝烟/黄烟现象及其排入大气环境后转化为二次气溶胶等问题,已引起广泛关注。燃煤电厂SO₃的排放主要由煤燃烧以及SCR烟气脱硝中SO₂氧化形成,随着选择性催化还原（SCR）脱硝设施的推广应用及高硫煤使用量的增多,控制燃煤SO₃排放已迫在眉睫。本文分析综述了燃煤烟气SO₃在SCR脱硝过程、低低温电除尘、湿法烟气脱硫以及湿式电除尘中的生成、迁移转化及脱除特性。同时介绍了两类控制燃煤烟气系统中SO₃的技术,一是利用现有污染物控制设备的协同作用;二是喷射碱性吸收剂吸收SO₃,综合比较了各类碱性吸收剂以及不同喷射位置,提出一种将喷碱性吸收剂与脱硫废水烟道蒸发技术相结合的控制方法。最后指出探究烟气系统中SO₃迁移转化特性以及碱性吸附剂脱除SO₃的反应机理及其影响因素是未来燃煤烟气SO₃控制技术研究的发展方向。     

臭氧氧化脱硝技术研究进展

区别于还原法脱硝技术,臭氧氧化脱硝技术将NO氧化为易溶于水的NO₂和N₂O₅等,结合后续吸收工艺进行脱硝。臭氧氧化脱硝技术已经广泛应用于催化裂化、工业锅炉烟气NO_x排放控制。结合臭氧氧化技术的工艺特点及反应动力学,分析了复杂烟气组分中NO氧化的选择性,重点关注臭氧与NO摩尔比、反应温度和停留时间等关键工艺参数对氧化产物组成的影响。通过阐述湿法与半干法脱硫工艺中的硫硝协同吸收原理,分析吸收剂、吸收气体组成、添加剂等因素对吸收效率的影响。在此基础上,提出臭氧氧化脱硝技术研究中存在的不足以及此技术未来的发展前景。     

Simultaneous desulfurization and denitrification of flue gas by pre-ozonation combined with ammonia absorption

A process of simultaneous desulfurization and denitrification of flue gas was conducted in this study. The flue gas containing 200 mg·m^-3 NO, 1000-4000 mg·m^-3 SO₂, 3%-9% O₂, and 10%-20% CO₂ was first oxidized by O₃ and then absorbed by ammonia in a bubbling reactor. Increasing the ammonia concentration or the SO₂ content in flue gas can promote the absorption of NO_X and extend the effective absorption time. On the contrary, both increasing the absorbent temperature or the O₂ content shorten the effective absorption time of NO_X. The change of solution pH had substantial influence on NO_X absorption. In the presence of CO₂, the NO_X removal efficiency reached 89.2% when the absorbent temperature was raised to 60 °C, and the effective absorption time can be maintained for 8 h, which attribute to the buffering effect in the absorbent. Besides, both the addition of Na₂S₂O₃ and urea can promote the NO_X removal efficiency when the absorbent temperature is 25 °C, and the addition of Na₂S₂O₃ had achieved better results. The advantage of adding Na₂S₂O₃ became less evident at higher absorbent temperature and coexistence of CO₂. In all experiments, SO₂ removal efficiency was always above 99%, and it was basically not affected by the above factors.     

Degradation of pesticides in water using solar advanced oxidation processes

Alachlor, atrazine and diuron dissolved in water at 50, 25 and 30 mg/L, respectively were photodegraded by Fe²⁺/H₂O₂, Fe³⁺/H₂O₂, TiO₂ and TiO₂/Na₂S₂O₈ treatments driven by solar energy at pilot-plant scale using a compound parabolic collector (CPC) photoreactor. All the advanced oxidation processes (AOPs) employed mainly compared the TOC mineralisation rate to evaluate treatment effectiveness. Parent compound disappearance, anion release and oxidant consumption are discussed as a function of treatment time. The use of Fe²⁺ or Fe³⁺ showed no influence on the reaction rate under illumination and the reaction using 10 or 55 mg/L of iron was quite similar. TiO₂/Na₂S₂O₈ showed a quicker reaction rate than TiO₂ and a similar rate compared to photo-Fenton. The main difference found was between TiO₂/Na₂S₂O₈ and photo-Fenton, detected during atrazine degradation, where pesticide transformation into cyanuric acid was confirmed only for TiO₂/Na₂S₂O₈.     

V2O5@CeO2核壳微球结构的脱硝催化剂制备及其抗硫性能

利用静电自组装法制备了V₂O₅@CeO₂核壳微球结构,并负载在TiO₂上。考察了分散剂六偏磷酸钠（SHP（对表面zeta电位的影响,采用扫描电镜（SEM（、投射电镜（TEM（观察了核壳结构的形貌,并在固定床上进行了脱硝性能测试,并通过比表面积（BET（、氨气吸附漫反射（in situ DRIFTS（等进行表征。结果表明：SHP使纳米颗粒表面带负电,且一定范围内SHP浓度越高,zeta电位越大;含质量分数1%V₂O₅、5% CeO₂的催化剂,在260~400℃间具有80%以上的脱硝效率,对比了该核壳结构与传统浸渍法制备催化剂的抗硫抗水性,烟气中含15%（体积分数（H₂O,SO₂含量较低时,脱硝性能优于传统浸渍法制备的催化剂。     

高含水菌渣流化床燃烧NOx、SO2排放特性

采用流化床反应器，研究了高含水抗生素菌渣直接燃烧的NO_x、SO₂排放特性。结果表明，增加过量空气系数，NO_x排放浓度升高，SO₂排放浓度降低；升高燃烧温度，NO_x及SO₂排放浓度均升高；随着燃料含水率的增加，NO_x及SO₂排放浓度均呈现先降低后升高的趋势。空气分级燃烧能有效降低NO_x排放，二次风率增加，NO_x排放浓度显著降低；当二次风率为3/7时，NO_x排放浓度较传统燃烧降低50%。添加CaCO₃进行炉内脱硫，实验结果显示：随钙硫摩尔比（Ca/S）增加，SO₂排放浓度下降，当Ca/S 3时，SO₂排放浓度降低到25 mg·m^-3以下，脱硫效率超过99%。     

喷淋鼓泡塔内氨水对烟气中As2O3的吸收特性

喷淋鼓泡塔内的反应是典型的气液两相流,为研究喷淋鼓泡内氨水对烟气中As₂O₃吸收特性,探索新型喷淋鼓泡技术的污染物一体化控制潜力,以空气和SO₂为模拟烟气,利用喷淋鼓泡吸收塔研究了液气比、浸液深度、氨水质量浓度、SO₂质量浓度对氨水吸收气相As₂O₃的影响。研究表明：氨水对As₂O₃的吸收效率随液气比增加先增大后趋于平缓;浸液深度增大,氨水吸收As₂O₃的效率降低;As₂O₃与氨水中OH^-作用生成的AsO₃^3-溶于氨水实现氨水对As₂O₃的吸收,氨水吸收As₂O₃的效率随氨水质量浓度的增大先上升后下降;碱性环境下,SO₂与NH₃作用生成SO₃^2-的水解增加了溶液中OH^-,促进了氨水对As₂O₃的吸收,又因SO₃^2-水解产生HSO₃^-电离出H⁺对部分OH^-中和以及NH₃挥发等因素,促进作用表现为吸收效率随SO₂质量浓度的增加先上升后下降。在氨水质量浓度为0.07%、SO₂质量浓度为525mg/m³、液气比10L/m³、浸液深度5cm时吸收效率达到最大82%。     

(NH4)2S吸收净化冶炼烟气中SO2回收硫资源的方法

采用(NH₄)₂S溶液吸收净化高浓度SO₂烟气,得到(NH₄)₂S₂O₃和NH₄HSO₃的混合溶液并转移至高压反应釜中,控制反应条件,两种物质发生自氧化还原反应,生成硫磺和(NH₄)₂SO₄.实验考察了吸收SO₂过程和自氧化还原过程的影响条件,结果表明:在pH=3～7,SO₂气体流速300 ml·min^-1,(NH₄)₂S浓度为0.2～1.2 mol·L^-1,常温条件下,烟气中二氧化硫的吸收率达到99.8%以上,且无H₂S生成;在pH=2.5～3.0,温度为130℃条件下,反应进行1 h,硫磺收率达到95%以上,溶液经过蒸发结晶得到(NH₄)₂SO₄.用X射线衍射(XRD)和X射线荧光光谱(XRF)对硫磺和硫酸铵进行表征分析,结果表明:硫磺的纯度为99.14%,硫酸铵中氮元素含量为23.6%.     

Feasibility analysis of SO2 absorption using a hydrophilic ceramic membrane contactor

Hydrophilic ceramic membranes would be potential candidates for membrane gas absorption if they could be applied to appropriate separation processes. This study highlights a novel concept for the practical implementation of SO₂ absorption in hydrophilic ceramic membrane that exhibits outstanding thermal and mechanical stabilities. With this aim, we investigated experimentally the performance of SO₂ absorption into aqueous sodium hydroxide (NaOH) solution in a hydrophilic alumina (Al₂O₃) membrane contactor in terms of SO₂ removal efficiency and SO₂ mass transfer flux, and compared the performance with that in a hydrophobic one. A series of experiments were performed at various conditions over a NaOH concentration range of 0-1.0 mol·L^-1, a liquid flow rate range of 30-180 ml·min^-1, a gas flow rate range of 120-1000 ml·min^-1, an inlet SO₂ concentration range of 400-2000 μl·L^-1, and a temperature range of 10-35℃. It was found that the hydrophilic membrane was more competitive when using a NaOH concentration higher than 0.2 mol·L^-1. Furthermore, it can be inferred that the hydrophilic α-Al₂O₃ membrane exhibited exceptional long-term stability under 480 h continuous operation.     

Removal of nitric oxide from simulated flue gas using aqueous persulfate with activation of ferrous ethylenediaminetetraacetate in the rotating packed bed

Nitric oxide being a major gas pollutant has attracted much attention and various technologies have been developed to reduce NO emission to preserve the environment. Advanced persulfate oxidation technology is a workable and effective choice for wet flue gas denitrification due to its high efficiency and green advantages. However, NO absorption rate is limited and affected by mass transfer limitation of NO and aqueous persulfate in traditional reactors. In this study, a rotating packed bed (RPB) was employed as a gas–liquid absorption device to elevate the NO removal efficiency (η_NO) by aqueous persulfate ((NH₄)₂S₂O₈) activated by ferrous ethylenediaminetetraacetate (Fe²⁺-EDTA). The experimental results regarding the NO absorption were obtained by investigating the effect of various operating parameters on the removal efficiency of NO in RPB. Increasing the concentration of (NH₄)₂S₂O₈ and liquid–gas ratio could promoted the oxidation and absorption of NO while theη_NO decreased with the increase of the gas flow and NO concentration. In addition, improving the high gravity factor increased the η_NO and the total volumetric mass transfer coefficient (K_Gα) which raise the η_NO up to more than 75% under the investigated system. These observations proved that the RPB can enhance the gas–liquid mass transfer process in NO absorption. The correlation formula between K_Gα and the influencing factors was determined by regression calculation, which is used to guide the industrial scale-up application of the system in NO removal. The presence of O₂ also had a negative effect on the NO removal process and through electron spin resonance spectrometer detection and product analysis, it was revealed that Fe²⁺-EDTA activated (NH₄)₂S₂O₈ to produce •SO₄^–, •OH and •O₂^–, played a leading role in the oxidation of NO, to produce NO₃^– as the final product. The obtained results demonstrated a good applicable potential of RPB/PS/Fe²⁺-EDTA in the removal of NO from flue gases.