水汽相变促进烟气中细颗粒物成核长大特性研究

发布时间：2018-03-18 08:28

本文选题：燃煤飞灰　切入点：无机盐　出处：《工程科学与技术》2017年05期 　论文类型：期刊论文

【摘要】：针对燃煤烟气中细颗粒物粒径过小不易被传统除尘设备捕集的问题,提出利用水汽相变技术以提高湿法烟气脱硫(WFGD)系统中细颗粒物的脱除效率。首先对燃煤飞灰及无机盐气溶胶颗粒物在过饱和水汽环境下异质核化凝结长大特性进行了数值预测,计算结果显示,烟气温度约为323 K条件下,水蒸汽在细颗粒物表面异相凝结可使其粒径在极短时间内增大几十到几百倍,并且较高的水汽过饱和度和较大的细颗粒物初始粒径有利于细颗粒物异质核化凝结长大。为验证数值计算结果并考察水汽相变促进细颗粒物凝结长大并脱除的实际效果,基于湿法烟气脱硫系统利用PDA和ELPI两种测试仪器,对燃煤细颗粒物及无机盐气溶胶颗粒在过饱和水汽环境下核化凝结长大特性及脱除性能进行实验研究,脱硫后净烟气温度约为40~50℃。结果表明,燃煤飞灰和无机盐气溶胶颗粒粒径均可在极短时间内增大3~5倍,由亚微米级颗粒长大成微米级的含尘液滴,其中亲水性的无机盐气溶胶颗粒更易潮解逐渐形成溶液滴,在饱和度接近1时就能凝结长大;长大后的含尘液滴可被丝网除雾器有效捕集,因此水汽相变结合丝网除雾器可有效促进细颗粒物凝结长大并脱除,使细颗粒物数量浓度由9.5×10~6/cm~3显著降至5×10~6/cm~3左右,质量浓度也可由80 mg/m~3明显降至20 mg/m~3左右,相应的脱除效率分别高达50%和75%。
[Abstract]:For coal-fired flue gas fine particle size too small is not easy to be traditional equipment dust trapping problem, put forward to improve the wet flue gas desulfurization by vapor phase technique (WFGD) removal efficiency of fine particles in the system. Firstly, coal fly ash and inorganic salt aerosol particles in satiety and moisture environment of heterogeneous nuclear setting up characteristics of the numerical prediction, the calculation results show that the gas temperature is about 323 K under the condition of water vapor condensation in fine particulate surface phase can make the particle size in a very short period of time increases dozens to hundreds of times, and higher water vapor supersaturation and larger initial fine particle size is conducive to fine particles heterogeneous nucleation and grow up. The actual effect in order to verify the numerical results and the effects of water vapor phase promoting fine particles removal and condensation growth of wet flue gas desulfurization system by using PDA and ELPI two kinds of test instrument based on Is the coal fine particles and inorganic aerosol particles in the supersaturated vapor environment of nuclear condensation growth characteristics and removal performance were studied, desulphurized flue gas temperature is about 40~50 degrees. The results show that the increase of 3~5 times in a very short time, the coal ash and inorganic salt aerosol particles can fly from Asia micron particles grow into dust droplets containing micron, inorganic salt aerosol particles is more hydrophilic deliquescent gradually formed droplets of solution, the saturation is close to 1 will be able to condense growth; grow up dust droplets can be effectively capture screen in addition to mist, so that vapor phase combined with wire mesh demister can effectively promote the fine particles removal and condensation growth, the fine particle number concentration from 9.5 10~6/cm~3 to 5 * * was about 10~6/cm~3, the concentration of 80 mg/m~3 can also be significantly reduced to 20 mg/m~3, the corresponding removal rate. Up to 50% and 75%.

【作者单位】：四川大学水力学与山区河流开发保护国家重点实验室水利水电学院;江苏省能源系统过程转化与减排技术工程实验室南京师范大学能源与机械工程学院;
【基金】：国家自然科学基金资助项目(51506099;51606130;51376052;51676101) 江苏省自然科学基金资助项目(BK20161558)
【分类号】：X701

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