Study on mercury migration in a circulating fluidized bed combustion boiler

Mercury concentrations in the flue gas at the stack were measured using a sorbent trap method as per United States Environmental Protection Agency Method 30B (i.e.,USEPA 40 CFR Part 60 30B),and the sampling method has merits of convenient setup, simply operation and fast analysis.Field tests were conducted at a unit of the Circulating Fluidized Bed Combustion (CFBC).During the course of sampling the mercury in the flue gas, coal samples, bottom ash and fly ash were collected and analyzed.Rates of mercury material balance though the unit were calculated, and correctness and validity of mercury sampling method were certified.Mercury distributions in fly ash, bottom ash and flue gas were evaluated, and the results showed that firstly bottom ash of CFBC removed only 0.55% of total mercury, secondly removal efficiency of fly ash reaching 83.37%, in the end 16.08% of total mercury was emitted to the air.The determined data of mercury emissions show that the CFBC is a clean coal combustion technology of effectively removing mercury.