A Study on dry reaction technology to remove SO2 from industrial sites

Abstract

The entrained mixing reactor(ERx) is a dry flue gas cleaning process to remove certain pollutants like SO2, HCl and HF. The main principle of the reactor is to bring flue gas in an intensive contact with hydrated lime and recirculated particles in the entrained mixing reactor. The entrained mixing reactor operates as entrained spout bed in the manner of fast fluidization. The gas/solid mixture leaves the entrained mixing reactor at the top are separated in the bag filter system from a flue gas. The flue gas of the entrained mixing reactor is designed as a rectifying nozzle. Due to the high flue gas velocities in the rectifying nozzle the collapse of the spouted bed and the falling down of solid particles through the rectifying nozzle is avoided. After the outlet from the entrained mixing reactor are separated from the flue gas in bag filter system. The SO2 and HCl acidic gases removal performance in the real scale entrained mixing reactor which has 75,000Nm3/hr capacity using hydrated lime was verified in the Chapter 4. Long-term operation for half of year was conducted to verify the relationship between hydrated lime conversion and acidic gases removal in the real scale entrained mixing reactor(ERx) which installed at the commercial waste incineration plant. The outlet concentration of SO2 and HCl were maintained lower values than allowable emission concentration because hydrated lime have inherently higher specific surface area and abundant pores in the reactive form. Only when apply the entrained mixing reactor with higher reactivity of the hydrated lime and high residence time can enhance the high acidic gases removal efficiency. The average removal efficiency of SO2 and HCl with the hydrated lime in the real scale entrained mixing reactor are 89.5% and 97.5%, respectively. For the application of the real scale ERx which has 75,000Nm3/hr of capacity in the field of flue gas cleaning after waste incineration plant the contents of HCl of the flue gas is higher than the content of SO2. The average inlet SO2 and HCl concentration of the flue gas at the upstream of real scale ERx were 59ppm and 162ppm, respectively. The Korea government continues to tighten regulations in the energy and environment industry it becomes more and more important to find the right technology to meet the every growing need to reduce emissions. In order to meet the ever growing need it will become important to be open minded regarding new technologies to meet the decreasing emissions levels and to maintain the concept of best available control technology.