水泥厂立窑烟气适宜除尘方法研究

目的 提出小水泥厂立窑烟气应选用的适宜除尘方法。方法 根据ＧＢ／Ｔ１６１５７－１９９６固定污染源排气中颗粒物的测定和气态污染物的采样方法,并使用ＷＹ－１型烟道用７级冲击式尘粒分级仪等测定了立窑烟气的温度、露点温度、粉尘浓度、粉尘粒径分级组成等特性;测定了沉降室、旋风、冲击水浴、冲击－喷雾除尘器的粒径分级除尘效率等特性。结果 在上述基础上,将除尘器与尘源进行合理匹配,提出了排放达标的几种除尘器选型组

Studies on appropriate methods for dust scrubbing from dust-laden gas in shaft kilns of small-sized cement plants

OBJECTIVE: To study an appropriate method for dust scrubbing from dust-laden gas in the shaft kilns of small-sized cement plants. METHODS: Characteristics of dust-laden gas, including its temperature, dew point, dust concentration, diameters of dust particles and their distribution, as well as fractional dust collection efficiencies of the dust precipitator settling chamber, cyclone, impinging scrubber, impinging-spray scrubber, were measured according to the National Standards for Measurement of Particulate in Exhaust Gas Emitted from the Stationary Pollution Sources and Sampling Methods of Gaseous Pollutants (GB/T16157 - 1996), with a WY-1 In-stack 7-Stage Cascade Impactor for fractional dust collection. RESULTS: The fractional dust collection efficiency of the settling chamber for the particles greater than 12 microm was 72%, while that of the cyclone for the particles of 2 microm, 5 microm and 10 microm were 40.0%, 72.5% and 88.9%, respectively, and that of impinging scrubber was 55.0%, 91.0% and 98.9%, respectively; and that of impinging-spray scrubber were 96.0%, 99.2% and 99.6%, respectively. Results showed that 81% of the dust (by weight) from the shaft kilns were greater than 10 microm, so the settling chamber was effective for the removal of this fraction of dust. But dust particles behind the settling chamber were finer, and about 59% - 69% of them were less than 2 microm in diameters. In that case, the cyclone, impinging scrubber and impinging-spray scrubber could give an overall collection efficiency of 54%, 57% and 96%, respectively. Based on this, the following combination of dust collectors were adopted to meet the national standards for exhaust emission: a settling chamber plus an electrostatic precipitator, a settling chamber plus an impinging-spray scrubber and a settling chamber plus an impinging scrubber. The cement plants could select appropriate dust collectors according to their technical and economical conditions. CONCLUSION: Based on the results of the studies, appropriate dust collectors used to treat dust-laden gas from shaft kilns to meet the national standards for exhaust emission were recommended.