洗涤塔脱除燃烧源超细颗粒的实验研究

Removal of fine particles from combustion by condensation scrubbing

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。

Packed column scrubber in which vapor condensation with fine particles acting as nucleation nuclei was used to separate fine particles from combustion.The particle size distributions and concentrations before and after scrubbing were measured by the electrical low pressure impactor （ELPI）.The microstructure and major element compositions of fine particles were analyzed by scanning electron microscopy （SEM） and X-ray photoelectron spectroscopy （XPS） respectively.Based on this, the influences of operating parameters, such as the temperature difference between gas and water at the inlet of scrubber, the moisture contents of flue gas, liquid to gas rate, on the particle removal efficiency were investigated.The results showed that the morphology and compositions of the fine particles from coal and oil combustion were very different.The fine particles from coal combustion mainly were mineral substances of Si and Al, while the particles from oil combustion mainly were carbon.The removal efficiency of fine particles from coal combustion was higher than that of oil under the same conditions.It was also found that the removal efficiency increased with increasing inlet temperature difference between gas and liquid.When the temperature difference was the same, the condensational removal efficiency could be highly enhanced with increasing humidity of inlet gas.The influence of liquid to gas ratio was related to the existence of heterogeneous condensation in the packed column scrubber.The result indicated that fine particles could be effectively removed by the packed column in which supersaturation of vapor and corresponding droplet growth by heterogeneous condensation were able to be achieved by adjusting the moisture contents of the inlet gas and the inlet temperature difference between flue gas and water.