Separation of Fine Particles from Gas Streams by Condensational Growth

一些工业过程，包括焚烧炉和冶金过程，通常会排放大量的细颗粒。在一个正在运行的污水污泥焚化炉中进行的测量表明，重金属（包括镉、铬、镍、铅和锌）集中在离开焚化炉的细颗粒中（约0.25克伦）。通常安装文丘里洗涤器以去除这些烟气源中的颗粒。传统的洗涤器不能去除小于0.5微米的颗粒。本项目提出的工艺是利用穿透文丘里洗涤器的亚微米颗粒作为注入烟气中的蒸汽的冷凝核，使水蒸气过饱和。理论分析表明，在合理的蒸汽率和接触次数下，可以产生大至1.0微米的水滴。这些水滴（细颗粒的稀释悬浮液）用高效除雾器从烟气流中除去，并排入洗涤池。初步分析表明，使用该工艺，离开文丘里洗涤器的细颗粒物中的重金属可以减少90%。通过相对适度的建设努力，这里提出的工艺可以减少配备湿式洗涤器的焚化炉的细颗粒和重金属排放。该工艺适用于湿式洗涤器净化的烟气流，包括焚烧炉、冶金工艺和使用湿式洗涤器控制二氧化硫排放的燃煤电厂。＊＊＊

9360161 Sun A number of industrial processes, including incinerators and metallurgical processes, typically emit large numbers of fine particles. Measurements at an operating sewage sludge incinerator have shown that heavy metals (including Cadmium, Chromium, Nickel, Lead, and Zinc) are concentrated in the fine particle (approximately 0.25 mocrons) leaving the incinerators. Venturi scrubbers have been typically installed to remove particulate from these flue gas sources. The classical scrubbers are not capable of removing particles smaller than about 0.5 microns. The process proposed in this project is the use of the submicron particulate penetrating the Venturi scrubber as condensation nuclei for steam injected into the flue gas to supersaturate it with water vapor. Theoretical analyses show that water droplets as large as 1.0 micron can be produced with reasonable steam rates and contact times. These water droplets (a dilute suspension of the fine particulate) are removed from the flue gas stream with a high efficiency mist eliminator and drained to the scrubber sump. Preliminary analyses have shown that heavy metals in the fine particulate leaving the Venturi scrubber can be reduced by 90% using this process. With a relatively modest construction effort, the process proposed here can reduce fine particle and heavy metal emissions from incinerators equipped with wet scrubbers. The process is applicable to flue gas streams cleaned by wet scrubbers including incinerators, metallurgical processes, and coal-fired power plants with wet scrubbers for sulfur dioxide emission control. ***