水汽相变促进湿法脱硫净烟气中细颗粒物脱除的研究

结合脱硫净烟气特点,提出分别通过脱硫净烟气中加装氟塑料换热器降温、添加蒸汽、添加冷空气3种措施建立细颗粒物凝结长大所需的过饱和水汽环境,进而增强后续高效除雾器的拦截脱除效果。数值分析了3种措施的可行性,并利用燃煤热态试验平台,对比考察了不同方式促进细颗粒物脱除的效果。结果表明:典型工况下,加装氟塑料换热器、添加蒸汽、添加冷空气三种措施均可使脱硫净烟气中细颗粒物排放浓度降低35%以上;其中,加装氟塑料换热器降温措施对脱硫净烟气原始温度变化的适应性较强,细颗粒物脱除效率基本不随脱硫净烟气原始温度的变化而改变;添加蒸汽方式不适于脱硫净烟气温度较高的场合,且耗能较大;添加冷空气方式在脱硫净烟气温度较高(≥55℃)时效果显著,但所需冷空气的温度较低,存在来源困难等问题。     

化学团聚促进电除尘脱除PM_(2.5)的实验研究

燃煤排放细颗粒物是大气环境PM2.5增加的重要来源。采用燃煤热态实验系统,进行了在电除尘器入口烟气添加化学团聚剂以及协同脱硫废水蒸发处理促进电除尘脱除PM2.5的实验研究。实验考察了团聚剂添加前后PM2.5浓度及其粒度分布的变化,以及团聚剂浓度、添加点烟温、团聚剂溶液pH、烟气量、雾滴粒径等对PM2.5脱除效果的影响。结果表明,添加化学团聚液后,通过润湿作用、液桥力和吸附架桥作用可增强PM2.5之间的接触并促进团聚长大,PM2.5增大到原先的4倍左右,典型工况下电除尘器出口PM2.5浓度降低40%以上。增加团聚液浓度可促进PM2.5的脱除;适当降低团聚液pH有利于PM2.5的团聚。喷脱硫废水,电除尘器出口PM2.5浓度变化不大,加团聚剂后出口细颗粒物浓度降低。     

湿法脱硫协同去除细颗粒物的研究进展

石灰石-石膏湿法烟气脱硫（wet flue gas desulfurization,WFGD）工艺具有吸收剂来源广、成本低、脱硫效率高等优点,成为应用最广泛的烟气脱硫工艺。湿法脱硫过程中,燃煤烟气在喷淋浆液的洗涤作用下不仅能高效脱除SO₂而且可以协同去除细颗粒物,但同时存在石灰浆液夹带导致出口颗粒物浓度增加的问题。本文首先综述了湿法脱硫的应用现状,对比了湿法脱硫系统前后细颗粒物物性变化,然后概述了应用于湿法脱硫协同去除细颗粒物的新方法,包括脱硫塔内部结构调整以及促进细颗粒物凝聚长大,同时分析了湿法脱硫工艺中采用荷电细水雾吸附细颗粒物并增益脱除SO₂的可行性,以期为燃煤电厂细颗粒物排放控制提供借鉴。最后指出未来湿法脱硫技术不仅要实现高脱硫效率,而且能有效脱除未被静电除尘器脱除的细颗粒物,湿法脱硫技术的发展趋势是多种技术耦合实现多污染物的协同脱除。     

化学团聚促进电除尘脱除PM2.5的实验研究

燃煤排放细颗粒物是大气环境PM_2.5增加的重要来源。采用燃煤热态实验系统,进行了在电除尘器入口烟气添加化学团聚剂以及协同脱硫废水蒸发处理促进电除尘脱除PM_2.5的实验研究。实验考察了团聚剂添加前后PM_2.5浓度及其粒度分布的变化,以及团聚剂浓度、添加点烟温、团聚剂溶液pH、烟气量、雾滴粒径等对PM_2.5脱除效果的影响。结果表明,添加化学团聚液后,通过润湿作用、液桥力和吸附架桥作用可增强PM_2.5之间的接触并促进团聚长大,PM_2.5增大到原先的4倍左右,典型工况下电除尘器出口PM_2.5浓度降低40%以上。增加团聚液浓度可促进PM_2.5的脱除;适当降低团聚液pH有利于PM_2.5的团聚。喷脱硫废水,电除尘器出口PM_2.5浓度变化不大,加团聚剂后出口细颗粒物浓度降低。     

化学与湍流团聚耦合促进燃煤细颗粒物团聚与脱除

将化学团聚与湍流团聚技术耦合，实验研究了燃煤细颗粒物在化学与湍流团聚耦合作用下的团聚与脱除效果，以及颗粒物浓度、烟气温度、团聚液喷入量与烟气流速等因素对细颗粒物团聚与脱除效果的影响规律。结果表明，典型工况下化学-湍流耦合团聚能够进一步促进细颗粒物团聚长大以及静电除尘器对细颗粒物的脱除，其作用效果优于单独的化学与湍流团聚。随细颗粒物浓度的升高，团聚与脱除效率均逐渐下降，分别由49.2%与96.7%下降至35.3%与88.2%。随烟气温度与团聚液喷入量的增加，细颗粒物团聚与脱除效率均先升高后降低，并在180℃与12 L/h处达到最高值，团聚与脱除效率分别为44.7%与94.8%。随烟气流速的增加，细颗粒物团聚与脱除效率均逐渐升高，分别由30.5%与86.3%升高至50.2%与97.5%。     

脱硫废水蒸发脱除PM_(2.5)试验研究

提出一种促进燃煤烟气PM_(2.5)团聚长大及脱硫废水处理的新方法。采用燃煤热态实验系统,在静电除尘器入口烟道进行脱硫废水蒸发试验,考察脱硫废水蒸发对飞灰物性、电除尘性能的影响,以及添加化学团聚剂、喷嘴的粒径对脱硫废水蒸发脱除PM_(2.5)的影响。结果表明:脱硫废水蒸发后,烟气细颗粒物粒径由0.15增加到1.0μm左右;典型工况下,电除尘前蒸发脱硫废水提高PM_(2.5)脱除效率约10%;脱硫废水加入团聚剂,电除尘出口PM_(2.5)脱除效率提高25%以上;降低喷嘴粒径、增加团聚剂添加量均有利于PM_(2.5)团聚长大。     

石灰石石膏法脱硫浆液结晶特性研究

针对石灰石石膏法脱硫系统出口排放细颗粒物主要来源于脱硫浆液蒸发夹带,考察了脱硫操作条件、杂质以及脱硫添加剂等对脱硫浆液中脱硫产物结晶特性的影响,并初步确定出口烟气细颗粒物浓度与脱硫浆液晶体粒度的关系。结果表明,脱硫浆液中晶体主要为石膏,温度过高过低均不利于晶体的生长;减小石灰石粒度、提高脱硫浆液p H值、以及在脱硫浆液中添加Fe3+和F-会抑制晶体长大,促进微细晶体的生成,而添加脱硫增效剂TL-02能够有效抑制细小晶核的形成。脱硫浆液中晶体粒径与出口烟气中颗粒物浓度相关,增加浆液中晶体粒度,出口细颗粒物排放浓度降低,细颗粒物总体粒径增加。     

湿法脱硫中应用蒸汽相变原理协同脱除PM2.5的技术分析

SO2、PM2.5是燃煤的主要污染物,实现两者的同时高效脱除具有重要现实意义.依据蒸汽相变促进PM2.5凝并长大的原理及湿法脱硫工艺特征,对湿法脱硫系统中应用蒸汽相变原理协同脱除PM2.5的可行性及技术方案加以分析;指出改进湿法脱硫操作条件、促进脱硫净化湿烟气达到过饱和、添加润湿剂、采用低表面能材料作相变凝结室壁面等措施,有望协同实现脱除SO2和促进PM2.5凝并长大并高效脱除的目的.     

气液交叉流脱除氨法脱硫尾气颗粒物的实验研究

氨法脱硫过程伴有大量气溶胶的生成,其尾气中颗粒物的浓度难以达到愈发严格国家相关环境标准。本文应用扫描电迁移率粒径谱仪对氨法脱硫尾气中气溶胶颗粒物的浓度和粒度分布进行测量,并采用气液交叉流系统对该尾气中颗粒物进行脱除,以探究气速、粒径对脱除率影响。     

石灰石-石膏法烟气脱硫过程中细颗粒物形成特性

利用石灰石-石膏湿法烟气脱硫模拟试验装置分析探讨脱硫净烟气中细颗粒物物性与脱硫浆液中晶体粒度分布、浓度、形貌及元素组成间的关系,并试验考察了烟气组分及脱硫工艺条件对脱硫净烟气中细颗粒物排放的影响。结果发现:石灰石-石膏湿法烟气脱硫过程中可生成大量亚微米级细颗粒,生成的细颗粒物性与脱硫浆液中晶体物性存在密切关系,脱硫操作参数如空塔气速、液气比等对脱硫浆液液滴夹带量存在显著影响;脱硫浆液蒸发夹带是石灰石-石膏法脱硫过程中生成细颗粒物的主要来源,通过抑制细小石膏晶粒的形成及优化脱硫工艺参数可减少石灰石-石膏湿法脱硫过程中细颗粒的形成。     

Removal of fine particles by heterogeneous condensation in the double-alkali desulfurization process

Removal of fine particles by heterogeneous condensation in the rotating-stream-tray scrubber was investigated experimentally for the double-alkali desulfurization process in this paper. A supersaturated vapor phase, necessary for condensational growth of fine particles, was achieved in the SO₂ absorption zone and at the top of the scrubber by adding steam in the gas inlet, between the pieces of rotating-stream-tray and above the desulfurization liquid inlet of the scrubber, respectively. Fine particles grew in size by vapor heterogeneous condensation with the particles acting as nucleation centers. Then the condensational grown droplets were removed efficiently by the desulfurization liquid and a high-efficiency demister. In order to optimize the removal process, the influences of temperature of inlet flue gas and desulfurization liquid, steam addition method and amount of steam added on the particle removal efficiency were presented. The results show that a few fine particles could be removed in the rotating-stream-tray scrubber. The removal efficiency can be significantly improved for various steam addition cases, and the improve performance is related to the method and the amount of steam addition. Particle removal efficiency with steam added between the pieces of rotating-stream-tray is higher than that of else steam addition cases.     

润湿剂促进燃油细颗粒捕集的实验研究

在反应室中研究了雾化液滴与燃油细颗粒的相互作用机制。提出了一种润湿剂对细颗粒捕集促进的新方法,用于研究颗粒与液滴作用前后颗粒数浓度和粒径分布变化特性及细颗粒的捕集特性。采用电称低压冲击器（ELPI）在线测试分析颗粒数浓度和粒径分布特性,用SEM和EDS分析了颗粒的形态和元素组分对捕集机理的影响。结果表明：颗粒的物化特性与液滴对颗粒的捕集作用密切相关;燃油排放颗粒主要为球形含炭疏水颗粒;雾化液滴对其的捕集效率较低;添加润湿剂有利于提高液滴对燃油细颗粒的捕集效率,添加Silanol w22比用纯水液滴对颗粒的捕集效率提高了15%;不同润湿剂对捕集效率的促进作用差别较大。研究结果可以用于对不同润湿剂除尘效果进行测试和筛选。     

Removal of fine particles in wet flue gas desulfurization system by heterogeneous condensation

A novel process to remove fine particles with high efficiency by heterogeneous condensation in a wet flue gas desulfurization (WFGD) system is presented. A supersaturated vapor phase, necessary for condensational growth of fine particles, was achieved in the SO₂ absorption zone and at the top of the wet FGD scrubber by adding steam in the gas inlet and above the scrubbing liquid inlet of the scrubber, respectively. The condensational grown droplets were then removed by the scrubbing liquid and a high-efficiency demister. The results show that the effectiveness of the WFGD system for removal of fine particles is related to the SO₂ absorbent employed. When using CaCO₃ and NH₃·H₂O to remove SO₂ from flue gas, the fine particle removal efficiencies are lower than those for Na₂CO₃ and water, and the morphology and elemental composition of fine particles are changed. This effect can be attributed to the formation of aerosol particles in the limestone and ammonia-based FGD processes. The performance of the WFGD system for removal of fine particles can be significantly improved for both steam addition cases, for which the removal efficiency increases with increasing amount of added steam. A high liquid to gas ratio is beneficial for efficient removal of fine particles by heterogeneous condensation of water vapor.     

Experimental investigation on removal of coal-fired fine particles by a condensation scrubber

The removal of coal-fired fine particles by heterogeneous condensation of water vapor in a scrubber was investigated. Supersaturated vapor phase necessary for the condensation growth of fine particles was achieved in the scrubbing zone as well as in the top of the scrubber by means of steam addition in the gas inlet and above the scrubbing liquid inlet, respectively. The condensation grown droplets were then removed by the scrubbing liquid and high-efficient demister. Influences of the steam addition amount, the temperature difference between the inlet gas and scrubbing liquid, and the liquid-to-gas ratio, etc. on removal efficiency were examined. The results show that with a steam addition amount of flue gas, number removal efficiencies of more than 60% and 70% can be attained for the two cases of steam addition, respectively. For the cases with steam addition in the gas inlet of scrubber, higher temperature difference between the inlet gas and scrubbing liquid enhances the removal of fine particles. Under the conditions of steam addition above the scrubbing liquid inlet, the removal efficiency decreases with increasing temperature difference. The removal efficiency can be effectively improved by increasing the liquid-to-gas ratio for both steam addition modes.     

亲水改性碳钢极板用于PM2.5脱除

火电厂大气污染物排放标准日趋严格,湿式静电除尘器作为终端治理设备逐渐得到广泛应用。以亲水改性刚性极板为研究对象,建立了卧式湿式静电除尘器中试实验台,开展了PM_2.5脱除特性的实验研究,研究了改性极板表面水膜增强颗粒物脱除效率的机制,考察了气体温度、停留时间、工作电压、初始浓度、冲洗水流量等主要运行参数对颗粒物脱除效率的影响规律。结果表明：改性刚性极板表面的纤维层可以减少反冲气流,减少颗粒的电迁移阻力;表面在小水量情况下亦可维持均匀稳定的水膜,水膜的存在抑制了反电晕和二次扬尘的发生,使得电晕电流高且水膜蒸发使烟气湿度提高,颗粒荷电量和电迁移速度提高,这两方面均提高了颗粒脱除效率。停留时间延长、工作电压提高均会引起颗粒脱除效率的增加,但颗粒物入口浓度、冲洗水流量对颗粒脱除效率影响不大。使用改性刚性极板的湿式静电除尘器可减少阳极冲洗水量,对粒径0.04～0.48 μm的颗粒有较高脱除效率,可在低电压下达到较高的颗粒物总脱除效率,具有较好的应用前景。     

洗涤塔脱除燃烧源超细颗粒的实验研究

在填料洗涤塔中进行了利用蒸汽相变原理促进燃煤和燃油超细颗粒凝结长大并高效脱除的实验研究;采用电称低压冲击器(ELPI)、SEM及XPS对两种燃烧源细颗粒凝结洗涤前后的数浓度、粒径分布、形貌和元素组分进行了分析测试,考察了洗涤塔进口气液温差、进口烟气含湿量及液气比等对脱除效率的影响。结果表明,燃煤和燃油产生的超细颗粒形貌和组分具有较大的差别,燃煤超细颗粒主要为硅铝矿物质,而燃油超细颗粒主要为含炭物质;在相同条件下,燃煤超细颗粒相变脱除效果优于燃油超细颗粒;脱除效率随洗涤塔进口气液温差的增大而提高,在相同进口气液温差下,增大进口烟气含湿量可显著提高超细颗粒的脱除效率;液气比的影响与填料洗涤塔内是否存在蒸汽相变有关;通过合理调节进口烟气含湿量及进口烟气与洗涤液的温差在填料塔内建立微粒凝结长大所需的过饱和水汽环境可有效脱除燃烧源超细颗粒。     

Removal of SO2 in Semi‐Dry Flue Gas Desulfurization Process with a Powder‐Particle Spouted Bed

Semi‐dry flue gas desulfurization was investigated with several kinds of SO₂ sorbents, such as slaked lime, limestone, Mg(OH)₂ and concrete pile sludge, in a powder‐particle spouted bed. Slurry droplets including sorbent fine particles were fed to a spouted bed of coarse inert particles spouted with hot gas containing SO₂. SO₂ removal efficiency was strongly affected by the approach to saturation temperature, Ca/S molar ratio and particle size of sorbent. Slaked lime showed the highest desulfurization efficiency. In this process, despite very short gas residence time, more than 90% SO₂ removal was easily achieved by choosing appropriate conditions.