The Design Of Circulated Fluidized Bed Boiler With Electrostatic-Bag Type Dust Collector

The topic-the large-scale coal-fired electric power plant boiler flue dust bag composite technology and equipment is from "large-scale coal-fired power plant boiler flue gas emission control technology and equipment",which is the third batch of key research projects that has been regarded by 863 Program Office of Technology Resources and Environment(POTRE).With the rapid development of industrial construction and over the country the standards of dust emissions for soot is more and more strict,and it is necessary to strengthen the control of air pollutants and dust emissions.Early in 2004 on the promulgation of the "power plant air emissions standards"(National Institute of Standards 13223-2003),many power plants switch to use low sulfur coal,reduce the concentration of sulfur dioxide,which leads to the resistance of soot increasing,the efficiency of dust of electrostatic precipitators is in reducing,it is too difficult for coal-fired utility boilers of the original electrostatic precipitators to reach the new emissions requirements(50mg/m~3).Therefore,it's time to carry out technological transformation.In this paper,by the pre-theoretical calculation of collection efficiency electrostatic precipitator and the analysis of the distribution of test-dust of flue gas after the dust of the track,it could be concluded that a suitable electric field is needed in front of the electrostatic precipitator dust.The paper also used the k-εturbulence model of CFD numerical simulation to study the air bag filter uniformity of the possibility of using the project and the actual use of the bag filter dust is almost similar to the cabinet to do the physical model.By simulating the resistance bag,filter wind speed,distance,and other parameters change bag,it can be concluded that airflow distribution in bag-house is imparity,particularly the filtration velocity of different location of the bag,and the velocity outer part of the bag-house is higher than the inner part.The velocity gradually becomes low from top down(from the air export row) of every single bag.Based on studies,the airflow should be designed with low velocity from the bottom of the bag-house;the distance between the filter bags should be much larger,and velocity should be much lower,too.The research on the pulse-jet system with CFD numerical simulation showed that when the airflow is injected into the bags,due to the larger speed,there is a negative area at the bottom of the bags,which results that the air into bags;because the high-speed airflow from the mouth spray injection into the bag when injecting,the velocity decays rapidly,the moving become into a hydrostatic pressure,the speed at the end of bag almost zero,both inside and outside of the bag more pressure,better cleaning.From the top to the bottom of its 600mm,the pressure inside the bag smaller, but also the existence of negative pressure,when the air flow through the filter bag, the speed is much smaller,in this section of the cleaning effect is rather poor.In the middle of the bag,the reverse airflow through the filter bag to keep in the 20m per seconds or more,and the pressure inside the bag is also much larger,which is in favor of cleaning.I take part in the whole issue of the participation of a power plant in Shanxi circulating fluidized bed boiler tail of the transformation of electrostatic precipitator's renovation project,and design for the electrostatic-bag combined type dust collector. Before the transformation,the emission of dust is 268.15mg/Nm~3,after the transformation,the emission of dust is merely 9.81mg/Nm~3,and it reduces 1641 tons of dust in every year.Now it has achieved significant environmental and social benefits.